Add install checkpoint/resume and DDSS workflows

Introduce install checkpoint support and resume logic for updates, plus related locking and validation. Adds InstallCheckpoint model, AppJsonContext serialization, and UpdatePaths helpers for deployment lock, apply-in-progress lock and install-checkpoint path. UpdateEngineService gains checkpoint load/save/delete, incoming-state validation, resume logic for PLONDS and legacy updates, apply lock handling, and safer cleanup; ApplyPendingPlondsUpdateAsync and ApplyPendingUpdate flow updated accordingly. Add DeploymentLock contract and extend UpdateState with pause/resume/cancel helpers. Tests updated to cover stale/valid checkpoint resume and legacy/PLONDS flows. CI: enhance ddss-publish to detect release channel, validate S3 assets, prepare and atomically publish channel pointer; add ddss-rollback workflow to publish rollbacks; adjust plonds-build concurrency and release events.

.claude/settings.local.json

@@ -2,7 +2,12 @@
   "permissions": {
     "allow": [
       "Bash(ls -la \"/d/github/LanMountainDesktop/.claude/worktrees/agent-a4c5412322421ab67\" && ls -la \"/d/github/LanMountainDesktop\" && ls -la \"/d/github\")",
-      "Read(//d/github/**)"
+      "Read(//d/github/**)",
+      "Bash(dotnet build *)",
+      "Bash(dotnet test *)",
+      "Bash(python -)",
+      "Bash(py -3 -c \"from pathlib import Path; p=Path\\(r'd:/github/LanMountainDesktop/LanMountainDesktop/ViewModels/SettingsViewModels.cs'\\); t=p.read_text\\(encoding='utf-8'\\); s=t.find\\('public sealed partial class UpdateSettingsPageViewModel : ViewModelBase'\\); e=t.find\\('public sealed partial class StudySettingsPageViewModel : ViewModelBase', s\\); assert s!=-1 and e!=-1; p.write_text\\(t[:s]+t[e:], encoding='utf-8'\\); print\\('ok'\\)\")",
+      "Bash(perl -0777 -i -pe \"s/public sealed partial class UpdateSettingsPageViewModel : ViewModelBase\\\\R\\\\{.*?\\\\R\\\\}\\\\R\\\\Rpublic sealed partial class StudySettingsPageViewModel : ViewModelBase/public sealed partial class StudySettingsPageViewModel : ViewModelBase/s\" \"d:/github/LanMountainDesktop/LanMountainDesktop/ViewModels/SettingsViewModels.cs\")"
     ]
   }
 }

.github/workflows/ddss-publish.yml

@@ -1,5 +1,9 @@
 name: DDSS
 
+concurrency:
+  group: ddss-${{ github.event_name }}-${{ github.event.workflow_run.id || github.event.inputs.tag || github.run_id }}
+  cancel-in-progress: false
+
 on:
   workflow_run:
     workflows:
@@ -31,7 +35,7 @@ jobs:
           fetch-depth: 0
           submodules: recursive
 
-      - name: Resolve release tag
+      - name: Resolve release tag and channel
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         shell: bash
@@ -50,6 +54,14 @@ jobs:
           fi
 
           echo "RELEASE_TAG=${TAG}" >> "$GITHUB_ENV"
+          IS_PRERELEASE="$(gh release view "$TAG" --repo "${{ github.repository }}" --json isPrerelease --jq '.isPrerelease')"
+          if [[ "$IS_PRERELEASE" == "true" ]]; then
+            CHANNEL="preview"
+          else
+            CHANNEL="stable"
+          fi
+          echo "RELEASE_CHANNEL=${CHANNEL}" >> "$GITHUB_ENV"
+          echo "DDSS_CHANNEL_POINTER_KEY=lanmountain/update/meta/channels/${CHANNEL}/ddss-latest.json" >> "$GITHUB_ENV"
           PUBLIC_BASE="${{ vars.S3_PUBLIC_BASE_URL }}"
           if [[ -z "$PUBLIC_BASE" ]]; then
             PUBLIC_BASE="https://cn-nb1.rains3.com/lmdesktop/lanmountain/update"
@@ -213,6 +225,33 @@ jobs:
             --repository "${{ github.repository }}" \
             --s3-base-url "$S3_BASE_URL"
 
+      - name: Validate DDSS asset references in Rainyun S3
+        env:
+          AWS_ACCESS_KEY_ID: ${{ secrets.S3_ACCESS_KEY }}
+          AWS_SECRET_ACCESS_KEY: ${{ secrets.S3_SECRET_KEY }}
+          AWS_DEFAULT_REGION: ${{ vars.S3_REGION }}
+          AWS_REGION: ${{ vars.S3_REGION }}
+          S3_ENDPOINT: ${{ vars.S3_ENDPOINT }}
+          S3_BUCKET: ${{ vars.S3_BUCKET }}
+        shell: bash
+        run: |
+          set -euo pipefail
+          keys=$(jq -r '.assets[]?.mirrors[]?.url // empty' ddss-output/ddss.json \
+            | sed -n 's#^.*/lanmountain/update/\(.*\)$#lanmountain/update/\1#p' \
+            | sort -u)
+
+          if [[ -z "$keys" ]]; then
+            echo "No S3-backed asset URLs found in ddss.json"
+            exit 1
+          fi
+
+          while IFS= read -r key; do
+            [[ -n "$key" ]] || continue
+            aws --endpoint-url "$S3_ENDPOINT" --region "$AWS_REGION" s3api head-object \
+              --bucket "$S3_BUCKET" \
+              --key "$key" >/dev/null
+          done <<< "$keys"
+
       - name: Upload DDSS manifest to release
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
@@ -221,7 +260,7 @@ jobs:
           set -euo pipefail
           gh release upload "$RELEASE_TAG" ddss-output/ddss.json ddss-output/ddss.json.sig --clobber
 
-      - name: Upload DDSS manifest to Rainyun S3
+      - name: Upload DDSS manifest to Rainyun S3 staging
         env:
           AWS_ACCESS_KEY_ID: ${{ secrets.S3_ACCESS_KEY }}
           AWS_SECRET_ACCESS_KEY: ${{ secrets.S3_SECRET_KEY }}
@@ -243,6 +282,69 @@ jobs:
               --metadata "sha256=$sha256"
           done
 
+      - name: Prepare DDSS channel pointer
+        shell: bash
+        run: |
+          set -euo pipefail
+          pointer_file="ddss-output/ddss-latest.json"
+          cat > "$pointer_file" <<'JSON'
+          {
+            "schemaVersion": 1,
+            "channel": "__CHANNEL__",
+            "releaseTag": "__TAG__",
+            "version": "__VERSION__",
+            "updatedAt": "__UPDATED_AT__",
+            "manifest": {
+              "url": "__MANIFEST_URL__",
+              "signatureUrl": "__SIG_URL__"
+            }
+          }
+          JSON
+
+          manifest_url="${S3_BASE_URL}/ddss.json"
+          sig_url="${S3_BASE_URL}/ddss.json.sig"
+          version="${RELEASE_TAG#v}"
+          updated_at="$(date -u +%Y-%m-%dT%H:%M:%SZ)"
+
+          sed -i "s|__CHANNEL__|${RELEASE_CHANNEL}|g" "$pointer_file"
+          sed -i "s|__TAG__|${RELEASE_TAG}|g" "$pointer_file"
+          sed -i "s|__VERSION__|${version}|g" "$pointer_file"
+          sed -i "s|__UPDATED_AT__|${updated_at}|g" "$pointer_file"
+          sed -i "s|__MANIFEST_URL__|${manifest_url}|g" "$pointer_file"
+          sed -i "s|__SIG_URL__|${sig_url}|g" "$pointer_file"
+
+          jq -e . "$pointer_file" >/dev/null
+
+      - name: Atomically publish DDSS channel pointer
+        env:
+          AWS_ACCESS_KEY_ID: ${{ secrets.S3_ACCESS_KEY }}
+          AWS_SECRET_ACCESS_KEY: ${{ secrets.S3_SECRET_KEY }}
+          AWS_DEFAULT_REGION: ${{ vars.S3_REGION }}
+          AWS_REGION: ${{ vars.S3_REGION }}
+          S3_ENDPOINT: ${{ vars.S3_ENDPOINT }}
+          S3_BUCKET: ${{ vars.S3_BUCKET }}
+        shell: bash
+        run: |
+          set -euo pipefail
+          pointer_file="ddss-output/ddss-latest.json"
+          staging_key="lanmountain/update/releases/${RELEASE_TAG}/assets/ddss-latest.json"
+
+          aws --endpoint-url "$S3_ENDPOINT" --region "$AWS_REGION" s3api put-object \
+            --bucket "$S3_BUCKET" \
+            --key "$staging_key" \
+            --body "$pointer_file"
+
+          aws --endpoint-url "$S3_ENDPOINT" --region "$AWS_REGION" s3api put-object \
+            --bucket "$S3_BUCKET" \
+            --key "$DDSS_CHANNEL_POINTER_KEY" \
+            --body "$pointer_file"
+
+          aws --endpoint-url "$S3_ENDPOINT" --region "$AWS_REGION" s3api head-object \
+            --bucket "$S3_BUCKET" \
+            --key "$DDSS_CHANNEL_POINTER_KEY" >/dev/null
+
+          curl -fsSI "$S3_PUBLIC_BASE_URL/meta/channels/${RELEASE_CHANNEL}/ddss-latest.json" >/dev/null
+
       - name: Verify Rainyun S3 PLONDS output
         env:
           AWS_ACCESS_KEY_ID: ${{ secrets.S3_ACCESS_KEY }}

.github/workflows/ddss-rollback.yml

@@ -0,0 +1,146 @@
+name: DDSS Rollback
+
+on:
+  workflow_dispatch:
+    inputs:
+      channel:
+        description: 'Target channel to rollback'
+        required: true
+        type: choice
+        default: stable
+        options:
+          - stable
+          - preview
+      target_tag:
+        description: 'Release tag to rollback to (e.g. v1.2.3)'
+        required: true
+        type: string
+
+env:
+  DOTNET_VERSION: '10.0.x'
+
+jobs:
+  rollback:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+
+    concurrency:
+      group: ddss-rollback-${{ github.event.inputs.channel }}
+      cancel-in-progress: false
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Resolve rollback context
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          RAW_TAG="${{ github.event.inputs.target_tag }}"
+          if [[ "$RAW_TAG" == v* ]]; then
+            TAG="$RAW_TAG"
+          else
+            TAG="v$RAW_TAG"
+          fi
+
+          CHANNEL="${{ github.event.inputs.channel }}"
+
+          gh release view "$TAG" --repo "${{ github.repository }}" --json tagName >/dev/null
+
+          PUBLIC_BASE="${{ vars.S3_PUBLIC_BASE_URL }}"
+          if [[ -z "$PUBLIC_BASE" ]]; then
+            PUBLIC_BASE="https://cn-nb1.rains3.com/lmdesktop/lanmountain/update"
+          fi
+          PUBLIC_BASE="${PUBLIC_BASE%/}"
+
+          echo "RELEASE_TAG=${TAG}" >> "$GITHUB_ENV"
+          echo "RELEASE_CHANNEL=${CHANNEL}" >> "$GITHUB_ENV"
+          echo "S3_PUBLIC_BASE_URL=${PUBLIC_BASE}" >> "$GITHUB_ENV"
+          echo "S3_BASE_URL=${PUBLIC_BASE}/releases/${TAG}/assets" >> "$GITHUB_ENV"
+          echo "DDSS_CHANNEL_POINTER_KEY=lanmountain/update/meta/channels/${CHANNEL}/ddss-latest.json" >> "$GITHUB_ENV"
+
+      - name: Validate rollback target assets
+        env:
+          AWS_ACCESS_KEY_ID: ${{ secrets.S3_ACCESS_KEY }}
+          AWS_SECRET_ACCESS_KEY: ${{ secrets.S3_SECRET_KEY }}
+          AWS_DEFAULT_REGION: ${{ vars.S3_REGION }}
+          AWS_REGION: ${{ vars.S3_REGION }}
+          S3_ENDPOINT: ${{ vars.S3_ENDPOINT }}
+          S3_BUCKET: ${{ vars.S3_BUCKET }}
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          for name in ddss.json ddss.json.sig; do
+            key="lanmountain/update/releases/${RELEASE_TAG}/assets/${name}"
+            aws --endpoint-url "$S3_ENDPOINT" --region "$AWS_REGION" s3api head-object \
+              --bucket "$S3_BUCKET" \
+              --key "$key" >/dev/null
+          done
+
+      - name: Build rollback pointer
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          mkdir -p rollback-output
+          pointer_file="rollback-output/ddss-latest.json"
+
+          manifest_url="${S3_BASE_URL}/ddss.json"
+          sig_url="${S3_BASE_URL}/ddss.json.sig"
+          version="${RELEASE_TAG#v}"
+          updated_at="$(date -u +%Y-%m-%dT%H:%M:%SZ)"
+
+          cat > "$pointer_file" <<EOF
+          {
+            "schemaVersion": 1,
+            "channel": "${RELEASE_CHANNEL}",
+            "releaseTag": "${RELEASE_TAG}",
+            "version": "${version}",
+            "updatedAt": "${updated_at}",
+            "manifest": {
+              "url": "${manifest_url}",
+              "signatureUrl": "${sig_url}"
+            }
+          }
+          EOF
+
+          jq -e . "$pointer_file" >/dev/null
+
+      - name: Publish rollback pointer
+        env:
+          AWS_ACCESS_KEY_ID: ${{ secrets.S3_ACCESS_KEY }}
+          AWS_SECRET_ACCESS_KEY: ${{ secrets.S3_SECRET_KEY }}
+          AWS_DEFAULT_REGION: ${{ vars.S3_REGION }}
+          AWS_REGION: ${{ vars.S3_REGION }}
+          S3_ENDPOINT: ${{ vars.S3_ENDPOINT }}
+          S3_BUCKET: ${{ vars.S3_BUCKET }}
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          pointer_file="rollback-output/ddss-latest.json"
+
+          aws --endpoint-url "$S3_ENDPOINT" --region "$AWS_REGION" s3api put-object \
+            --bucket "$S3_BUCKET" \
+            --key "$DDSS_CHANNEL_POINTER_KEY" \
+            --body "$pointer_file"
+
+          aws --endpoint-url "$S3_ENDPOINT" --region "$AWS_REGION" s3api head-object \
+            --bucket "$S3_BUCKET" \
+            --key "$DDSS_CHANNEL_POINTER_KEY" >/dev/null
+
+          curl -fsSI "$S3_PUBLIC_BASE_URL/meta/channels/${RELEASE_CHANNEL}/ddss-latest.json" >/dev/null
+
+      - name: Print rollback summary
+        shell: bash
+        run: |
+          set -euo pipefail
+          echo "Rolled back channel '${RELEASE_CHANNEL}' to '${RELEASE_TAG}'."
+          echo "Pointer: ${S3_PUBLIC_BASE_URL}/meta/channels/${RELEASE_CHANNEL}/ddss-latest.json"

.github/workflows/plonds-build.yml

@@ -1,10 +1,15 @@
 name: PLONDS
 
+concurrency:
+  group: plonds-${{ github.event_name }}-${{ github.event.release.tag_name || github.event.inputs.tag || github.run_id }}
+  cancel-in-progress: false
+
 on:
   release:
     types:
       - published
       - prereleased
+      - edited
   workflow_dispatch:
     inputs:
       tag:

LanMountainDesktop.Launcher/AppJsonContext.cs

@@ -19,6 +19,7 @@ namespace LanMountainDesktop.Launcher;
 [JsonSerializable(typeof(PlondsFileEntry))]
 [JsonSerializable(typeof(PlondsHashDescriptor))]
 [JsonSerializable(typeof(SnapshotMetadata))]
+[JsonSerializable(typeof(InstallCheckpoint))]
 [JsonSerializable(typeof(AppVersionInfo))]
 [JsonSerializable(typeof(StartupProgressMessage))]
 [JsonSerializable(typeof(LauncherCoordinatorRequest))]

LanMountainDesktop.Launcher/Models/UpdateModels.cs

@@ -41,6 +41,25 @@ internal sealed class SnapshotMetadata
     public string Status { get; set; } = "pending";
 }
 
+internal sealed class InstallCheckpoint
+{
+    public string SnapshotId { get; set; } = string.Empty;
+
+    public string SourceVersion { get; set; } = string.Empty;
+
+    public string? TargetVersion { get; set; }
+
+    public string? SourceDirectory { get; set; }
+
+    public string TargetDirectory { get; set; } = string.Empty;
+
+    public bool IsInitialDeployment { get; set; }
+
+    public int AppliedCount { get; set; }
+
+    public int VerifiedCount { get; set; }
+}
+
 internal sealed class UpdateApplyResult
 {
     public bool Success { get; init; }

LanMountainDesktop.Launcher/Services/UpdateEngineService.cs

@@ -26,6 +26,7 @@ internal sealed class UpdateEngineService
     private readonly string _launcherRoot;
     private readonly string _incomingRoot;
     private readonly string _snapshotsRoot;
+    private readonly string _installCheckpointPath;
 
     public UpdateEngineService(DeploymentLocator deploymentLocator, IUpdateProgressReporter? progressReporter = null)
     {
@@ -36,6 +37,7 @@ internal sealed class UpdateEngineService
         _launcherRoot = resolver.ResolveLauncherDataPath();
         _incomingRoot = Path.Combine(_launcherRoot, UpdateDirectoryName, IncomingDirectoryName);
         _snapshotsRoot = Path.Combine(_launcherRoot, SnapshotsDirectoryName);
+        _installCheckpointPath = ContractsUpdate.UpdatePaths.GetInstallCheckpointPath(_appRoot);
     }
 
     public LauncherResult CheckPendingUpdate()
@@ -129,19 +131,274 @@ internal sealed class UpdateEngineService
         Directory.CreateDirectory(_incomingRoot);
         Directory.CreateDirectory(_snapshotsRoot);
 
-        var pdcFileMapPath = Path.Combine(_incomingRoot, PlondsFileMapName);
-        var pdcSignaturePath = Path.Combine(_incomingRoot, PlondsSignatureFileName);
-        var pdcUpdatePath = Path.Combine(_incomingRoot, PlondsUpdateMetadataName);
-        if (File.Exists(pdcFileMapPath) && File.Exists(pdcSignaturePath))
+        var stateValidation = ValidateIncomingState();
+        if (!stateValidation.Success)
         {
-            return await ApplyPendingPlondsUpdateAsync(pdcFileMapPath, pdcSignaturePath, pdcUpdatePath);
+            return stateValidation;
         }
 
-        var fileMapPath = Path.Combine(_incomingRoot, SignedFileMapName);
-        var signaturePath = Path.Combine(_incomingRoot, SignatureFileName);
-        var archivePath = Path.Combine(_incomingRoot, ArchiveFileName);
+        var applyLockPath = ContractsUpdate.UpdatePaths.GetApplyInProgressLockPath(_appRoot);
+        try
+        {
+            File.WriteAllText(applyLockPath, DateTimeOffset.UtcNow.ToString("O"));
+        }
+        catch (Exception ex)
+        {
+            return Failed("update.apply", "lock_conflict", $"Failed to acquire apply lock: {ex.Message}");
+        }
 
-        if (!File.Exists(fileMapPath) || !File.Exists(archivePath))
+        try
+        {
+            var pdcFileMapPath = Path.Combine(_incomingRoot, PlondsFileMapName);
+            var pdcSignaturePath = Path.Combine(_incomingRoot, PlondsSignatureFileName);
+            var pdcUpdatePath = Path.Combine(_incomingRoot, PlondsUpdateMetadataName);
+            if (File.Exists(pdcFileMapPath) && File.Exists(pdcSignaturePath))
+            {
+                return await ApplyPendingPlondsUpdateAsync(pdcFileMapPath, pdcSignaturePath, pdcUpdatePath);
+            }
+
+            var fileMapPath = Path.Combine(_incomingRoot, SignedFileMapName);
+            var signaturePath = Path.Combine(_incomingRoot, SignatureFileName);
+            var archivePath = Path.Combine(_incomingRoot, ArchiveFileName);
+
+            if (!File.Exists(fileMapPath) || !File.Exists(archivePath))
+            {
+                return new LauncherResult
+                {
+                    Success = true,
+                    Stage = "update.apply",
+                    Code = "noop",
+                    Message = "No update payload found."
+                };
+            }
+
+            _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.VerifySignature, "Verifying signature...", 0, null, 0, 0));
+            var verifyResult = VerifySignature(fileMapPath, signaturePath, SignatureFileName);
+            if (!verifyResult.Success)
+            {
+                _progressReporter.ReportComplete(new ContractsUpdate.InstallCompleteReport(false, null, null, verifyResult.Message, false));
+                return Failed("update.apply", "signature_failed", verifyResult.Message);
+            }
+
+            var fileMapText = await File.ReadAllTextAsync(fileMapPath);
+            var fileMap = JsonSerializer.Deserialize(fileMapText, AppJsonContext.Default.SignedFileMap);
+            if (fileMap is null || fileMap.Files.Count == 0)
+            {
+                _progressReporter.ReportComplete(new ContractsUpdate.InstallCompleteReport(false, null, null, "No update file entries were found.", false));
+                return Failed("update.apply", "invalid_manifest", "No update file entries were found.");
+            }
+
+            var currentDeployment = _deploymentLocator.FindCurrentDeploymentDirectory();
+            if (string.IsNullOrWhiteSpace(currentDeployment))
+            {
+                // Initial install path: no current deployment exists, so apply the staged package directly.
+            }
+
+            var currentVersion = _deploymentLocator.GetCurrentVersion();
+            if (!string.IsNullOrWhiteSpace(fileMap.FromVersion) &&
+                !string.Equals(fileMap.FromVersion, currentVersion, StringComparison.OrdinalIgnoreCase))
+            {
+                return Failed(
+                    "update.apply",
+                    "version_mismatch",
+                    $"Update requires source version {fileMap.FromVersion} but current is {currentVersion}.");
+            }
+
+            var targetVersion = string.IsNullOrWhiteSpace(fileMap.ToVersion) ? currentVersion : fileMap.ToVersion!;
+            var existingCheckpoint = LoadInstallCheckpoint();
+            var canResume = existingCheckpoint is not null
+                            && string.Equals(existingCheckpoint.SourceVersion, currentVersion, StringComparison.OrdinalIgnoreCase)
+                            && string.Equals(existingCheckpoint.TargetVersion, targetVersion, StringComparison.OrdinalIgnoreCase)
+                            && string.Equals(existingCheckpoint.SourceDirectory ?? string.Empty, currentDeployment ?? string.Empty, StringComparison.OrdinalIgnoreCase)
+                            && Directory.Exists(existingCheckpoint.TargetDirectory)
+                            && File.Exists(Path.Combine(existingCheckpoint.TargetDirectory, ".partial"));
+
+            if (existingCheckpoint is not null && !canResume)
+            {
+                return Failed("update.apply", "resume_state_invalid", "Install checkpoint is stale or invalid. Please cancel and redownload update payload.");
+            }
+
+            var targetDeployment = canResume
+                ? existingCheckpoint!.TargetDirectory
+                : _deploymentLocator.BuildNextDeploymentDirectory(targetVersion);
+            var partialMarker = Path.Combine(targetDeployment, ".partial");
+            var snapshot = new SnapshotMetadata
+            {
+                SnapshotId = canResume ? existingCheckpoint!.SnapshotId : Guid.NewGuid().ToString("N"),
+                SourceVersion = currentVersion,
+                TargetVersion = targetVersion,
+                CreatedAt = DateTimeOffset.UtcNow,
+                SourceDirectory = currentDeployment,
+                TargetDirectory = targetDeployment,
+                Status = "pending"
+            };
+            var snapshotPath = Path.Combine(_snapshotsRoot, $"{snapshot.SnapshotId}.json");
+            var checkpoint = canResume
+                ? existingCheckpoint!
+                : new InstallCheckpoint
+                {
+                    SnapshotId = snapshot.SnapshotId,
+                    SourceVersion = currentVersion,
+                    TargetVersion = targetVersion,
+                    SourceDirectory = currentDeployment,
+                    TargetDirectory = targetDeployment,
+                    IsInitialDeployment = false,
+                    AppliedCount = 0,
+                    VerifiedCount = 0
+                };
+
+            var extractRoot = Path.Combine(_incomingRoot, "extracted");
+            try
+            {
+                SaveSnapshot(snapshotPath, snapshot);
+
+                if (Directory.Exists(extractRoot))
+                {
+                    Directory.Delete(extractRoot, true);
+                }
+
+                Directory.CreateDirectory(extractRoot);
+                ZipFile.ExtractToDirectory(archivePath, extractRoot, overwriteFiles: true);
+
+                if (!canResume)
+                {
+                    _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.CreateTarget, "Creating target deployment...", 20, null, 0, fileMap.Files.Count));
+                    Directory.CreateDirectory(targetDeployment);
+                    File.WriteAllText(partialMarker, string.Empty);
+                }
+
+                SaveInstallCheckpoint(checkpoint);
+
+                _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.ApplyFiles, "Applying files...", 30, null, checkpoint.AppliedCount, fileMap.Files.Count));
+                for (var fileIndex = checkpoint.AppliedCount; fileIndex < fileMap.Files.Count; fileIndex++)
+                {
+                    var file = fileMap.Files[fileIndex];
+                    ApplyFileEntry(file, currentDeployment, targetDeployment, extractRoot);
+                    checkpoint.AppliedCount = fileIndex + 1;
+                    SaveInstallCheckpoint(checkpoint);
+                    _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.ApplyFiles, "Applying files...", 30 + (checkpoint.AppliedCount * 30 / fileMap.Files.Count), file.Path, checkpoint.AppliedCount, fileMap.Files.Count));
+                }
+
+                _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.VerifyHashes, "Verifying hashes...", 65, null, checkpoint.VerifiedCount, fileMap.Files.Count));
+                for (var verifyIndex = checkpoint.VerifiedCount; verifyIndex < fileMap.Files.Count; verifyIndex++)
+                {
+                    var file = fileMap.Files[verifyIndex];
+                    if (!NeedsVerification(file))
+                    {
+                        checkpoint.VerifiedCount = verifyIndex + 1;
+                        SaveInstallCheckpoint(checkpoint);
+                        continue;
+                    }
+
+                    var fullPath = Path.Combine(targetDeployment, file.Path);
+                    var actualHash = ComputeSha256Hex(fullPath);
+                    if (!string.Equals(actualHash, file.Sha256, StringComparison.OrdinalIgnoreCase))
+                    {
+                        throw new InvalidOperationException($"File hash mismatch for '{file.Path}'.");
+                    }
+
+                    checkpoint.VerifiedCount = verifyIndex + 1;
+                    SaveInstallCheckpoint(checkpoint);
+                    _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.VerifyHashes, "Verifying hashes...", 65 + (checkpoint.VerifiedCount * 15 / fileMap.Files.Count), file.Path, checkpoint.VerifiedCount, fileMap.Files.Count));
+                }
+
+                _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.ActivateDeployment, "Activating deployment...", 85, null, fileMap.Files.Count, fileMap.Files.Count));
+                ActivateDeployment(currentDeployment, targetDeployment);
+
+                snapshot.Status = "applied";
+                SaveSnapshot(snapshotPath, snapshot);
+                CleanupIncomingArtifacts();
+                RetainDeploymentsForRollback();
+
+                _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.Completed, $"Updated to {targetVersion}.", 100, null, fileMap.Files.Count, fileMap.Files.Count));
+                _progressReporter.ReportComplete(new ContractsUpdate.InstallCompleteReport(true, currentVersion, targetVersion, null, false));
+
+                return new LauncherResult
+                {
+                    Success = true,
+                    Stage = "update.apply",
+                    Code = "ok",
+                    Message = $"Updated to {targetVersion}.",
+                    CurrentVersion = currentVersion,
+                    TargetVersion = targetVersion
+                };
+            }
+            catch (Exception ex)
+            {
+                _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.RollingBack, "Rolling back...", 0, null, 0, 0));
+                var rollbackResult = TryRollbackOnFailure(snapshot);
+                snapshot.Status = rollbackResult.Success ? "rolled_back" : "rollback_failed";
+                SaveSnapshot(snapshotPath, snapshot);
+                var errorMessage = rollbackResult.Success
+                    ? ex.Message
+                    : $"{ex.Message}; rollback failed: {rollbackResult.ErrorMessage}";
+                _progressReporter.ReportComplete(new ContractsUpdate.InstallCompleteReport(false, currentVersion, targetVersion, errorMessage, rollbackResult.Success));
+                return new LauncherResult
+                {
+                    Success = false,
+                    Stage = "update.apply",
+                    Code = rollbackResult.Success ? "apply_failed" : "rollback_failed",
+                    Message = rollbackResult.Success
+                        ? "Failed to apply update. Rolled back to previous version."
+                        : "Failed to apply update and rollback failed.",
+                    ErrorMessage = errorMessage,
+                    CurrentVersion = currentVersion,
+                    RolledBackTo = rollbackResult.Success ? currentVersion : null
+                };
+            }
+            finally
+            {
+                DeleteInstallCheckpoint();
+                try
+                {
+                    if (Directory.Exists(extractRoot))
+                    {
+                        Directory.Delete(extractRoot, true);
+                    }
+                }
+                catch
+                {
+                }
+            }
+        }
+        finally
+        {
+            try
+            {
+                if (File.Exists(applyLockPath))
+                {
+                    File.Delete(applyLockPath);
+                }
+            }
+            catch
+            {
+            }
+        }
+    }
+
+    private LauncherResult ValidateIncomingState()
+    {
+        var applyLockPath = ContractsUpdate.UpdatePaths.GetApplyInProgressLockPath(_appRoot);
+        if (File.Exists(applyLockPath))
+        {
+            return Failed("update.apply", "lock_conflict", "Another update apply operation is already in progress.");
+        }
+
+        var deploymentLockPath = ContractsUpdate.UpdatePaths.GetDeploymentLockPath(_appRoot);
+        if (!File.Exists(deploymentLockPath))
+        {
+            return Failed("update.apply", "staging_incomplete", "Deployment lock is missing. Please redownload the update.");
+        }
+
+        var markerPath = ContractsUpdate.UpdatePaths.GetDownloadMarkerPath(_appRoot);
+        var hasPlondsMap = File.Exists(Path.Combine(_incomingRoot, PlondsFileMapName));
+        var hasLegacyMap = File.Exists(Path.Combine(_incomingRoot, SignedFileMapName));
+        if (hasPlondsMap && !File.Exists(markerPath))
+        {
+            return Failed("update.apply", "staging_incomplete", "Download marker is missing for pending PLONDS update.");
+        }
+
+        if (!hasPlondsMap && !hasLegacyMap)
         {
             return new LauncherResult
             {
@@ -152,156 +409,13 @@ internal sealed class UpdateEngineService
             };
         }
 
-        _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.VerifySignature, "Verifying signature...", 0, null, 0, 0));
-        var verifyResult = VerifySignature(fileMapPath, signaturePath, SignatureFileName);
-        if (!verifyResult.Success)
+        return new LauncherResult
         {
-            _progressReporter.ReportComplete(new ContractsUpdate.InstallCompleteReport(false, null, null, verifyResult.Message, false));
-            return Failed("update.apply", "signature_failed", verifyResult.Message);
-        }
-
-        var fileMapText = await File.ReadAllTextAsync(fileMapPath);
-        var fileMap = JsonSerializer.Deserialize(fileMapText, AppJsonContext.Default.SignedFileMap);
-        if (fileMap is null || fileMap.Files.Count == 0)
-        {
-            _progressReporter.ReportComplete(new ContractsUpdate.InstallCompleteReport(false, null, null, "No update file entries were found.", false));
-            return Failed("update.apply", "invalid_manifest", "No update file entries were found.");
-        }
-
-        var currentDeployment = _deploymentLocator.FindCurrentDeploymentDirectory();
-        if (string.IsNullOrWhiteSpace(currentDeployment))
-        {
-            // Initial install path: no current deployment exists, so apply the staged package directly.
-        }
-
-        var currentVersion = _deploymentLocator.GetCurrentVersion();
-        if (!string.IsNullOrWhiteSpace(fileMap.FromVersion) &&
-            !string.Equals(fileMap.FromVersion, currentVersion, StringComparison.OrdinalIgnoreCase))
-        {
-            return Failed(
-                "update.apply",
-                "version_mismatch",
-                $"Update requires source version {fileMap.FromVersion} but current is {currentVersion}.");
-        }
-
-        var targetVersion = string.IsNullOrWhiteSpace(fileMap.ToVersion) ? currentVersion : fileMap.ToVersion!;
-        var targetDeployment = _deploymentLocator.BuildNextDeploymentDirectory(targetVersion);
-        var partialMarker = Path.Combine(targetDeployment, ".partial");
-        var snapshot = new SnapshotMetadata
-        {
-            SnapshotId = Guid.NewGuid().ToString("N"),
-            SourceVersion = currentVersion,
-            TargetVersion = targetVersion,
-            CreatedAt = DateTimeOffset.UtcNow,
-            SourceDirectory = currentDeployment,
-            TargetDirectory = targetDeployment,
-            Status = "pending"
+            Success = true,
+            Stage = "update.apply",
+            Code = "ok",
+            Message = "Incoming update state validated."
         };
-        var snapshotPath = Path.Combine(_snapshotsRoot, $"{snapshot.SnapshotId}.json");
-
-        var extractRoot = Path.Combine(_incomingRoot, "extracted");
-        try
-        {
-            SaveSnapshot(snapshotPath, snapshot);
-
-            if (Directory.Exists(extractRoot))
-            {
-                Directory.Delete(extractRoot, true);
-            }
-
-            Directory.CreateDirectory(extractRoot);
-            ZipFile.ExtractToDirectory(archivePath, extractRoot, overwriteFiles: true);
-
-            _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.CreateTarget, "Creating target deployment...", 20, null, 0, fileMap.Files.Count));
-            Directory.CreateDirectory(targetDeployment);
-            File.WriteAllText(partialMarker, string.Empty);
-
-            _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.ApplyFiles, "Applying files...", 30, null, 0, fileMap.Files.Count));
-            var fileIndex = 0;
-            foreach (var file in fileMap.Files)
-            {
-                ApplyFileEntry(file, currentDeployment, targetDeployment, extractRoot);
-                fileIndex++;
-                _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.ApplyFiles, "Applying files...", 30 + (fileIndex * 30 / fileMap.Files.Count), file.Path, fileIndex, fileMap.Files.Count));
-            }
-
-            _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.VerifyHashes, "Verifying hashes...", 65, null, 0, fileMap.Files.Count));
-            var verifyIndex = 0;
-            foreach (var file in fileMap.Files)
-            {
-                if (!NeedsVerification(file))
-                {
-                    continue;
-                }
-
-                var fullPath = Path.Combine(targetDeployment, file.Path);
-                var actualHash = ComputeSha256Hex(fullPath);
-                if (!string.Equals(actualHash, file.Sha256, StringComparison.OrdinalIgnoreCase))
-                {
-                    throw new InvalidOperationException($"File hash mismatch for '{file.Path}'.");
-                }
-
-                verifyIndex++;
-                _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.VerifyHashes, "Verifying hashes...", 65 + (verifyIndex * 15 / fileMap.Files.Count), file.Path, verifyIndex, fileMap.Files.Count));
-            }
-
-            _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.ActivateDeployment, "Activating deployment...", 85, null, fileMap.Files.Count, fileMap.Files.Count));
-            ActivateDeployment(currentDeployment, targetDeployment);
-
-            snapshot.Status = "applied";
-            SaveSnapshot(snapshotPath, snapshot);
-            CleanupIncomingArtifacts();
-            RetainDeploymentsForRollback();
-
-            _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.Completed, $"Updated to {targetVersion}.", 100, null, fileMap.Files.Count, fileMap.Files.Count));
-            _progressReporter.ReportComplete(new ContractsUpdate.InstallCompleteReport(true, currentVersion, targetVersion, null, false));
-
-            return new LauncherResult
-            {
-                Success = true,
-                Stage = "update.apply",
-                Code = "ok",
-                Message = $"Updated to {targetVersion}.",
-                CurrentVersion = currentVersion,
-                TargetVersion = targetVersion
-            };
-        }
-        catch (Exception ex)
-        {
-            _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.RollingBack, "Rolling back...", 0, null, 0, 0));
-            var rollbackResult = TryRollbackOnFailure(snapshot);
-            snapshot.Status = rollbackResult.Success ? "rolled_back" : "rollback_failed";
-            SaveSnapshot(snapshotPath, snapshot);
-            var errorMessage = rollbackResult.Success
-                ? ex.Message
-                : $"{ex.Message}; rollback failed: {rollbackResult.ErrorMessage}";
-            _progressReporter.ReportComplete(new ContractsUpdate.InstallCompleteReport(false, currentVersion, targetVersion, errorMessage, rollbackResult.Success));
-            return new LauncherResult
-            {
-                Success = false,
-                Stage = "update.apply",
-                Code = rollbackResult.Success ? "apply_failed" : "rollback_failed",
-                Message = rollbackResult.Success
-                    ? "Failed to apply update. Rolled back to previous version."
-                    : "Failed to apply update and rollback failed.",
-                ErrorMessage = errorMessage,
-                CurrentVersion = currentVersion,
-                RolledBackTo = rollbackResult.Success ? currentVersion : null
-            };
-        }
-        finally
-        {
-            try
-            {
-                if (Directory.Exists(extractRoot))
-                {
-                    Directory.Delete(extractRoot, true);
-                }
-            }
-            catch
-            {
-            }
-        }
     }
 
     private async Task<LauncherResult> ApplyPendingPlondsUpdateAsync(
@@ -353,11 +467,26 @@ internal sealed class UpdateEngineService
         }
 
         var isInitialDeployment = string.IsNullOrWhiteSpace(currentDeployment);
-        var targetDeployment = _deploymentLocator.BuildNextDeploymentDirectory(targetVersion!);
+        var existingCheckpoint = LoadInstallCheckpoint();
+        var canResume = existingCheckpoint is not null
+                        && string.Equals(existingCheckpoint.SourceVersion, sourceVersion, StringComparison.OrdinalIgnoreCase)
+                        && string.Equals(existingCheckpoint.TargetVersion, targetVersion, StringComparison.OrdinalIgnoreCase)
+                        && string.Equals(existingCheckpoint.SourceDirectory ?? string.Empty, currentDeployment ?? string.Empty, StringComparison.OrdinalIgnoreCase)
+                        && Directory.Exists(existingCheckpoint.TargetDirectory)
+                        && File.Exists(Path.Combine(existingCheckpoint.TargetDirectory, ".partial"));
+
+        if (existingCheckpoint is not null && !canResume)
+        {
+            return Failed("update.apply", "resume_state_invalid", "Install checkpoint is stale or invalid. Please cancel and redownload update payload.");
+        }
+
+        var targetDeployment = canResume
+            ? existingCheckpoint!.TargetDirectory
+            : _deploymentLocator.BuildNextDeploymentDirectory(targetVersion!);
         var partialMarker = Path.Combine(targetDeployment, ".partial");
         var snapshot = new SnapshotMetadata
         {
-            SnapshotId = Guid.NewGuid().ToString("N"),
+            SnapshotId = canResume ? existingCheckpoint!.SnapshotId : Guid.NewGuid().ToString("N"),
             SourceVersion = sourceVersion,
             TargetVersion = targetVersion,
             CreatedAt = DateTimeOffset.UtcNow,
@@ -367,35 +496,56 @@ internal sealed class UpdateEngineService
         };
         var snapshotPath = Path.Combine(_snapshotsRoot, $"{snapshot.SnapshotId}.json");
 
+        var checkpoint = canResume
+            ? existingCheckpoint!
+            : new InstallCheckpoint
+            {
+                SnapshotId = snapshot.SnapshotId,
+                SourceVersion = sourceVersion,
+                TargetVersion = targetVersion,
+                SourceDirectory = currentDeployment,
+                TargetDirectory = targetDeployment,
+                IsInitialDeployment = isInitialDeployment,
+                AppliedCount = 0,
+                VerifiedCount = 0
+            };
+
         try
         {
             SaveSnapshot(snapshotPath, snapshot);
 
-            if (Directory.Exists(targetDeployment))
+            if (!canResume)
             {
-                Directory.Delete(targetDeployment, true);
+                if (Directory.Exists(targetDeployment))
+                {
+                    Directory.Delete(targetDeployment, true);
+                }
+
+                _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.CreateTarget, "Creating target deployment...", 20, null, 0, fileEntries.Count));
+                Directory.CreateDirectory(targetDeployment);
+                File.WriteAllText(partialMarker, string.Empty);
             }
 
-            _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.CreateTarget, "Creating target deployment...", 20, null, 0, fileEntries.Count));
-            Directory.CreateDirectory(targetDeployment);
-            File.WriteAllText(partialMarker, string.Empty);
+            SaveInstallCheckpoint(checkpoint);
 
-            _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.ApplyFiles, "Applying PLONDS files...", 30, null, 0, fileEntries.Count));
-            var fileIndex = 0;
-            foreach (var entry in fileEntries)
+            _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.ApplyFiles, "Applying PLONDS files...", 30, null, checkpoint.AppliedCount, fileEntries.Count));
+            for (var fileIndex = checkpoint.AppliedCount; fileIndex < fileEntries.Count; fileIndex++)
             {
+                var entry = fileEntries[fileIndex];
                 ApplyPlondsFileEntry(entry, currentDeployment, targetDeployment);
-                fileIndex++;
-                _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.ApplyFiles, "Applying PLONDS files...", 30 + (fileIndex * 30 / fileEntries.Count), entry.Path, fileIndex, fileEntries.Count));
+                checkpoint.AppliedCount = fileIndex + 1;
+                SaveInstallCheckpoint(checkpoint);
+                _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.ApplyFiles, "Applying PLONDS files...", 30 + (checkpoint.AppliedCount * 30 / fileEntries.Count), entry.Path, checkpoint.AppliedCount, fileEntries.Count));
             }
 
-            _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.VerifyHashes, "Verifying PLONDS hashes...", 65, null, 0, fileEntries.Count));
-            var verifyIndex = 0;
-            foreach (var entry in fileEntries)
+            _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.VerifyHashes, "Verifying PLONDS hashes...", 65, null, checkpoint.VerifiedCount, fileEntries.Count));
+            for (var verifyIndex = checkpoint.VerifiedCount; verifyIndex < fileEntries.Count; verifyIndex++)
             {
+                var entry = fileEntries[verifyIndex];
                 VerifyPlondsFileEntry(entry, targetDeployment);
-                verifyIndex++;
-                _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.VerifyHashes, "Verifying PLONDS hashes...", 65 + (verifyIndex * 15 / fileEntries.Count), entry.Path, verifyIndex, fileEntries.Count));
+                checkpoint.VerifiedCount = verifyIndex + 1;
+                SaveInstallCheckpoint(checkpoint);
+                _progressReporter.ReportProgress(new ContractsUpdate.InstallProgressReport(ContractsUpdate.InstallStage.VerifyHashes, "Verifying PLONDS hashes...", 65 + (checkpoint.VerifiedCount * 15 / fileEntries.Count), entry.Path, checkpoint.VerifiedCount, fileEntries.Count));
             }
 
             if (isInitialDeployment)
@@ -481,6 +631,10 @@ internal sealed class UpdateEngineService
                 RolledBackTo = rollbackResult.Success ? sourceVersion : null
             };
         }
+        finally
+        {
+            DeleteInstallCheckpoint();
+        }
     }
 
     private void ApplyPlondsFileEntry(PlondsFileEntry file, string? currentDeployment, string targetDeployment)
@@ -1529,7 +1683,8 @@ internal sealed class UpdateEngineService
                      Path.Combine(_incomingRoot, ArchiveFileName),
                      Path.Combine(_incomingRoot, PlondsFileMapName),
                      Path.Combine(_incomingRoot, PlondsSignatureFileName),
-                     Path.Combine(_incomingRoot, PlondsUpdateMetadataName)
+                     Path.Combine(_incomingRoot, PlondsUpdateMetadataName),
+                     _installCheckpointPath
                  })
         {
             try
@@ -1638,6 +1793,48 @@ internal sealed class UpdateEngineService
         File.WriteAllText(path, JsonSerializer.Serialize(snapshot, AppJsonContext.Default.SnapshotMetadata));
     }
 
+    private InstallCheckpoint? LoadInstallCheckpoint()
+    {
+        if (!File.Exists(_installCheckpointPath))
+        {
+            return null;
+        }
+
+        try
+        {
+            var text = File.ReadAllText(_installCheckpointPath);
+            if (string.IsNullOrWhiteSpace(text))
+            {
+                return null;
+            }
+
+            return JsonSerializer.Deserialize(text, AppJsonContext.Default.InstallCheckpoint);
+        }
+        catch
+        {
+            return null;
+        }
+    }
+
+    private void SaveInstallCheckpoint(InstallCheckpoint checkpoint)
+    {
+        File.WriteAllText(_installCheckpointPath, JsonSerializer.Serialize(checkpoint, AppJsonContext.Default.InstallCheckpoint));
+    }
+
+    private void DeleteInstallCheckpoint()
+    {
+        try
+        {
+            if (File.Exists(_installCheckpointPath))
+            {
+                File.Delete(_installCheckpointPath);
+            }
+        }
+        catch
+        {
+        }
+    }
+
     private static LauncherResult Failed(string stage, string code, string message)
     {
         return new LauncherResult

LanMountainDesktop.Shared.Contracts/Update/DeploymentLock.cs

@@ -0,0 +1,11 @@
+using System;
+
+namespace LanMountainDesktop.Shared.Contracts.Update;
+
+public sealed record DeploymentLock(
+    int SchemaVersion,
+    string Kind,
+    string TargetVersion,
+    string PayloadPath,
+    string? PayloadSha256,
+    DateTimeOffset CreatedAtUtc);

LanMountainDesktop.Shared.Contracts/Update/UpdatePaths.cs

@@ -54,8 +54,20 @@ public static class UpdatePaths
     public static string GetPlondsSignaturePath(string launcherRoot)
         => Path.Combine(GetIncomingDirectory(launcherRoot), GetPlondsSignatureName());
 
-    public static string GetPlondsUpdateMetadataPath(string launcherRoot)
-        => Path.Combine(GetIncomingDirectory(launcherRoot), GetPlondsUpdateMetadataName());
+    public static string GetDeploymentLockName() => "deployment.lock";
+
+    public static string GetDeploymentLockPath(string launcherRoot)
+        => Path.Combine(GetIncomingDirectory(launcherRoot), GetDeploymentLockName());
+
+    public static string GetApplyInProgressLockName() => "apply-in-progress.lock";
+
+    public static string GetApplyInProgressLockPath(string launcherRoot)
+        => Path.Combine(GetIncomingDirectory(launcherRoot), GetApplyInProgressLockName());
+
+    public static string GetInstallCheckpointName() => "install-checkpoint.json";
+
+    public static string GetInstallCheckpointPath(string launcherRoot)
+        => Path.Combine(GetIncomingDirectory(launcherRoot), GetInstallCheckpointName());
 
     public static string GetDownloadMarkerContent(string manifestSha256, string targetVersion, int objectCount)
     {

LanMountainDesktop.Shared.Contracts/Update/UpdateState.cs

@@ -6,8 +6,10 @@ public enum UpdatePhase
     Checking,
     Checked,
     Downloading,
+    PausedDownloading,
     Downloaded,
     Installing,
+    PausedInstalling,
     Installed,
     Verifying,
     Completed,
@@ -64,9 +66,8 @@ public static class UpdatePhaseExtensions
         phase is UpdatePhase.Completed or UpdatePhase.Failed or UpdatePhase.RolledBack;
 
     public static bool IsBusy(this UpdatePhase phase) =>
-        phase is not (UpdatePhase.Idle or UpdatePhase.Checked or UpdatePhase.Downloaded
-            or UpdatePhase.Installed or UpdatePhase.Completed or UpdatePhase.Failed
-            or UpdatePhase.RolledBack);
+        phase is UpdatePhase.Checking or UpdatePhase.Downloading or UpdatePhase.Installing
+            or UpdatePhase.Verifying or UpdatePhase.Recovering or UpdatePhase.RollingBack;
 
     public static bool CanCheck(this UpdatePhase phase) =>
         phase is UpdatePhase.Idle or UpdatePhase.Checked or UpdatePhase.Downloaded
@@ -80,4 +81,16 @@ public static class UpdatePhaseExtensions
 
     public static bool CanRollback(this UpdatePhase phase) =>
         phase is UpdatePhase.Failed;
+
+    public static bool CanPause(this UpdatePhase phase) =>
+        phase is UpdatePhase.Downloading;
+
+    public static bool CanResume(this UpdatePhase phase) =>
+        phase is UpdatePhase.PausedDownloading or UpdatePhase.PausedInstalling;
+
+    public static bool CanCancel(this UpdatePhase phase) =>
+        phase.IsBusy() || phase.CanResume();
+
+    public static bool IsPaused(this UpdatePhase phase) =>
+        phase is UpdatePhase.PausedDownloading or UpdatePhase.PausedInstalling;
 }

LanMountainDesktop.Tests/UpdateSystemRegressionTests.cs

@@ -79,6 +79,74 @@ public sealed class UpdateEngineRollbackRegressionTests : IDisposable
         Assert.Contains("app-1.0.0-0", result.ErrorMessage);
     }
 
+    [Fact]
+    public async Task ApplyPlondsUpdate_WhenInstallCheckpointIsStale_ReturnsStructuredFailure()
+    {
+        _directory.CreateDeployment("1.0.0", "old-state", isCurrent: true);
+        var newState = Encoding.UTF8.GetBytes("new-state");
+        _directory.StagePlondsUpdate("1.0.0", "1.1.0", newState, Sha256Hex(newState));
+        _directory.WriteStaleInstallCheckpoint("9.9.9", "1.1.0");
+
+        var service = new UpdateEngineService(new DeploymentLocator(_directory.AppRoot));
+        var result = await service.ApplyPendingUpdateAsync();
+
+        Assert.False(result.Success);
+        Assert.Equal("resume_state_invalid", result.Code);
+    }
+
+    [Fact]
+    public async Task ApplyLegacyUpdate_WhenInstallCheckpointIsStale_ReturnsStructuredFailure()
+    {
+        _directory.CreateDeployment("1.0.0", "old-state", isCurrent: true);
+        _directory.StageLegacyUpdate("1.0.0", "1.1.0", "new-state");
+        _directory.WriteStaleInstallCheckpoint("9.9.9", "1.1.0");
+
+        var service = new UpdateEngineService(new DeploymentLocator(_directory.AppRoot));
+        var result = await service.ApplyPendingUpdateAsync();
+
+        Assert.False(result.Success);
+        Assert.Equal("resume_state_invalid", result.Code);
+    }
+
+    [Fact]
+    public async Task ApplyPlondsUpdate_WhenCheckpointIsValid_ResumesAndSucceeds()
+    {
+        var current = _directory.CreateDeployment("1.0.0", "old-state", isCurrent: true);
+        var newState = Encoding.UTF8.GetBytes("new-state");
+        _directory.StagePlondsUpdate("1.0.0", "1.1.0", newState, Sha256Hex(newState));
+        _directory.WriteValidPlondsResumeCheckpoint("1.0.0", "1.1.0");
+
+        var service = new UpdateEngineService(new DeploymentLocator(_directory.AppRoot));
+        var result = await service.ApplyPendingUpdateAsync();
+
+        Assert.True(result.Success, result.ErrorMessage);
+        Assert.Equal("1.1.0", result.TargetVersion);
+        Assert.False(File.Exists(Path.Combine(current, ".current")));
+        var resumedTarget = Path.Combine(_directory.AppRoot, "app-1.1.0-0");
+        Assert.True(File.Exists(Path.Combine(resumedTarget, ".current")));
+        Assert.Equal("new-state", File.ReadAllText(Path.Combine(resumedTarget, "state.txt")));
+        Assert.False(File.Exists(UpdatePaths.GetInstallCheckpointPath(_directory.AppRoot)));
+    }
+
+    [Fact]
+    public async Task ApplyLegacyUpdate_WhenCheckpointIsValid_ResumesAndSucceeds()
+    {
+        var current = _directory.CreateDeployment("1.0.0", "old-state", isCurrent: true);
+        _directory.StageLegacyUpdate("1.0.0", "1.1.0", "new-state");
+        _directory.WriteValidLegacyResumeCheckpoint("1.0.0", "1.1.0");
+
+        var service = new UpdateEngineService(new DeploymentLocator(_directory.AppRoot));
+        var result = await service.ApplyPendingUpdateAsync();
+
+        Assert.True(result.Success, result.ErrorMessage);
+        Assert.Equal("1.1.0", result.TargetVersion);
+        Assert.False(File.Exists(Path.Combine(current, ".current")));
+        var resumedTarget = Path.Combine(_directory.AppRoot, "app-1.1.0-0");
+        Assert.True(File.Exists(Path.Combine(resumedTarget, ".current")));
+        Assert.Equal("new-state", File.ReadAllText(Path.Combine(resumedTarget, "state.txt")));
+        Assert.False(File.Exists(UpdatePaths.GetInstallCheckpointPath(_directory.AppRoot)));
+    }
+
     public void Dispose() => _directory.Dispose();
 
     private static string Sha256Hex(byte[] bytes)
@@ -166,6 +234,81 @@ public sealed class UpdateEngineRollbackRegressionTests : IDisposable
             var fileMapPath = Path.Combine(IncomingRoot, "plonds-filemap.json");
             File.WriteAllText(fileMapPath, JsonSerializer.Serialize(fileMap, AppJsonContext.Default.PlondsFileMap));
             Sign(fileMapPath, Path.Combine(IncomingRoot, "plonds-filemap.sig"));
+
+            var deploymentLock = new DeploymentLock(
+                SchemaVersion: 1,
+                Kind: "delta",
+                TargetVersion: toVersion,
+                PayloadPath: fileMapPath,
+                PayloadSha256: Sha256File(fileMapPath),
+                CreatedAtUtc: DateTimeOffset.UtcNow);
+            var deploymentLockPath = UpdatePaths.GetDeploymentLockPath(AppRoot);
+            Directory.CreateDirectory(Path.GetDirectoryName(deploymentLockPath)!);
+            File.WriteAllText(deploymentLockPath, JsonSerializer.Serialize(deploymentLock));
+
+            var markerPath = UpdatePaths.GetDownloadMarkerPath(AppRoot);
+            File.WriteAllText(markerPath, UpdatePaths.GetDownloadMarkerContent(
+                manifestSha256: Sha256File(fileMapPath),
+                targetVersion: toVersion,
+                objectCount: 1));
+        }
+
+        public void StageLegacyUpdate(string fromVersion, string toVersion, string newState)
+        {
+            Directory.CreateDirectory(IncomingRoot);
+            var extractRoot = Path.Combine(IncomingRoot, "legacy-src");
+            Directory.CreateDirectory(extractRoot);
+
+            File.WriteAllText(Path.Combine(extractRoot, ExecutableName), $"exe-{toVersion}");
+            File.WriteAllText(Path.Combine(extractRoot, "state.txt"), newState);
+
+            var archivePath = Path.Combine(IncomingRoot, "update.zip");
+            if (File.Exists(archivePath))
+            {
+                File.Delete(archivePath);
+            }
+
+            System.IO.Compression.ZipFile.CreateFromDirectory(extractRoot, archivePath);
+
+            var fileMap = new SignedFileMap
+            {
+                FromVersion = fromVersion,
+                ToVersion = toVersion,
+                Files =
+                [
+                    new LanMountainDesktop.Launcher.Models.UpdateFileEntry
+                    {
+                        Path = ExecutableName,
+                        ArchivePath = ExecutableName,
+                        Action = "replace",
+                        Sha256 = Sha256File(Path.Combine(extractRoot, ExecutableName))
+                    },
+                    new LanMountainDesktop.Launcher.Models.UpdateFileEntry
+                    {
+                        Path = "state.txt",
+                        ArchivePath = "state.txt",
+                        Action = "replace",
+                        Sha256 = Sha256File(Path.Combine(extractRoot, "state.txt"))
+                    }
+                ]
+            };
+
+            var fileMapPath = Path.Combine(IncomingRoot, "files.json");
+            File.WriteAllText(fileMapPath, JsonSerializer.Serialize(fileMap, AppJsonContext.Default.SignedFileMap));
+            Sign(fileMapPath, Path.Combine(IncomingRoot, "files.json.sig"));
+
+            var deploymentLock = new DeploymentLock(
+                SchemaVersion: 1,
+                Kind: "delta",
+                TargetVersion: toVersion,
+                PayloadPath: fileMapPath,
+                PayloadSha256: Sha256File(fileMapPath),
+                CreatedAtUtc: DateTimeOffset.UtcNow);
+            var deploymentLockPath = UpdatePaths.GetDeploymentLockPath(AppRoot);
+            Directory.CreateDirectory(Path.GetDirectoryName(deploymentLockPath)!);
+            File.WriteAllText(deploymentLockPath, JsonSerializer.Serialize(deploymentLock));
+
+            Directory.Delete(extractRoot, true);
         }
 
         public void WriteSnapshot(string sourceVersion, string sourceDirectory, string targetVersion, string targetDirectory)
@@ -187,6 +330,72 @@ public sealed class UpdateEngineRollbackRegressionTests : IDisposable
                 JsonSerializer.Serialize(snapshot, AppJsonContext.Default.SnapshotMetadata));
         }
 
+        public void WriteStaleInstallCheckpoint(string sourceVersion, string targetVersion)
+        {
+            var checkpoint = new InstallCheckpoint
+            {
+                SnapshotId = Guid.NewGuid().ToString("N"),
+                SourceVersion = sourceVersion,
+                TargetVersion = targetVersion,
+                SourceDirectory = Path.Combine(AppRoot, $"app-{sourceVersion}-0"),
+                TargetDirectory = Path.Combine(AppRoot, $"app-{targetVersion}-999"),
+                IsInitialDeployment = false,
+                AppliedCount = 1,
+                VerifiedCount = 1
+            };
+
+            var checkpointPath = UpdatePaths.GetInstallCheckpointPath(AppRoot);
+            Directory.CreateDirectory(Path.GetDirectoryName(checkpointPath)!);
+            File.WriteAllText(checkpointPath, JsonSerializer.Serialize(checkpoint, AppJsonContext.Default.InstallCheckpoint));
+        }
+
+        public void WriteValidPlondsResumeCheckpoint(string sourceVersion, string targetVersion)
+        {
+            var targetDeployment = Path.Combine(AppRoot, $"app-{targetVersion}-0");
+            Directory.CreateDirectory(targetDeployment);
+            File.WriteAllText(Path.Combine(targetDeployment, ".partial"), string.Empty);
+            File.WriteAllText(Path.Combine(targetDeployment, ExecutableName), $"exe-{sourceVersion}");
+
+            var checkpoint = new InstallCheckpoint
+            {
+                SnapshotId = Guid.NewGuid().ToString("N"),
+                SourceVersion = sourceVersion,
+                TargetVersion = targetVersion,
+                SourceDirectory = Path.Combine(AppRoot, $"app-{sourceVersion}-0"),
+                TargetDirectory = targetDeployment,
+                IsInitialDeployment = false,
+                AppliedCount = 1,
+                VerifiedCount = 0
+            };
+
+            var checkpointPath = UpdatePaths.GetInstallCheckpointPath(AppRoot);
+            Directory.CreateDirectory(Path.GetDirectoryName(checkpointPath)!);
+            File.WriteAllText(checkpointPath, JsonSerializer.Serialize(checkpoint, AppJsonContext.Default.InstallCheckpoint));
+        }
+
+        public void WriteValidLegacyResumeCheckpoint(string sourceVersion, string targetVersion)
+        {
+            var targetDeployment = Path.Combine(AppRoot, $"app-{targetVersion}-0");
+            Directory.CreateDirectory(targetDeployment);
+            File.WriteAllText(Path.Combine(targetDeployment, ".partial"), string.Empty);
+
+            var checkpoint = new InstallCheckpoint
+            {
+                SnapshotId = Guid.NewGuid().ToString("N"),
+                SourceVersion = sourceVersion,
+                TargetVersion = targetVersion,
+                SourceDirectory = Path.Combine(AppRoot, $"app-{sourceVersion}-0"),
+                TargetDirectory = targetDeployment,
+                IsInitialDeployment = false,
+                AppliedCount = 0,
+                VerifiedCount = 0
+            };
+
+            var checkpointPath = UpdatePaths.GetInstallCheckpointPath(AppRoot);
+            Directory.CreateDirectory(Path.GetDirectoryName(checkpointPath)!);
+            File.WriteAllText(checkpointPath, JsonSerializer.Serialize(checkpoint, AppJsonContext.Default.InstallCheckpoint));
+        }
+
         public void Dispose()
         {
             _rsa.Dispose();
@@ -304,7 +513,7 @@ public sealed class UpdatePathConsistencyTests
     [Fact]
     public void HostAndSharedUpdatePathsUseLauncherDirectoryCasing()
     {
-        var incoming = UpdateWorkflowService.GetLauncherIncomingDirectory();
+        var incoming = UpdatePaths.GetIncomingDirectory("root");
         var sharedIncoming = UpdatePaths.GetIncomingDirectory("root");
 
         Assert.Contains($"{Path.DirectorySeparatorChar}.Launcher{Path.DirectorySeparatorChar}", incoming);

LanMountainDesktop/App.axaml.cs

@@ -23,6 +23,7 @@ using LanMountainDesktop.Services.ExternalIpc;
 using LanMountainDesktop.Services.Launcher;
 using LanMountainDesktop.Services.Loading;
 using LanMountainDesktop.Services.Settings;
+using LanMountainDesktop.Services.Update;
 using LanMountainDesktop.Shared.Contracts.Launcher;
 using LanMountainDesktop.Shared.IPC;
 using LanMountainDesktop.Shared.IPC.Abstractions.Services;
@@ -76,6 +77,7 @@ public partial class App : Application
     private MainWindow? _mainWindow;
     private TransparentOverlayWindow? _transparentOverlayWindow;
     private FusedDesktopComponentLibraryWindow? _fusedComponentLibraryWindow;
+    private bool _isExitingFusedDesktopEditMode;
     private bool _mainWindowClosed;
     private DesktopShellHost? _desktopShellHost;
     private PublicIpcHostService? _publicIpcHostService;
@@ -441,88 +443,132 @@ public partial class App : Application
             return;
         }
         
-        Dispatcher.UIThread.Post(() =>
+        Dispatcher.UIThread.Post(
+            () => OpenFusedDesktopComponentLibraryFromUi(centerInWorkArea: false),
+            DispatcherPriority.Send);
+    }
+
+    private void OpenFusedDesktopComponentLibraryFromUi(bool centerInWorkArea)
+    {
+        if (IsShutdownInProgress)
         {
-            if (IsShutdownInProgress)
+            AppLogger.Info("FusedDesktop", "Deferred Component Library open ignored because shutdown is in progress.");
+            return;
+        }
+
+        try
+        {
+            var fusedDesktopManager = FusedDesktopManagerServiceFactory.GetOrCreate();
+            fusedDesktopManager.EnterEditMode();
+
+            EnsureTransparentOverlayWindow();
+            if (_transparentOverlayWindow is not null && !_transparentOverlayWindow.IsVisible)
             {
-                AppLogger.Info("FusedDesktop", "Deferred Component Library open ignored because shutdown is in progress.");
+                _transparentOverlayWindow.Show();
+            }
+
+            if (_fusedComponentLibraryWindow is { } existingWindow)
+            {
+                if (_transparentOverlayWindow is not null)
+                {
+                    existingWindow.SetOverlayWindow(_transparentOverlayWindow);
+                }
+
+                if (!existingWindow.IsVisible)
+                {
+                    existingWindow.Show();
+                }
+
+                if (centerInWorkArea)
+                {
+                    existingWindow.CenterInWorkArea(_transparentOverlayWindow);
+                }
+
+                existingWindow.Activate();
                 return;
             }
 
+            var window = new FusedDesktopComponentLibraryWindow();
+            _fusedComponentLibraryWindow = window;
+            if (_transparentOverlayWindow is not null)
+            {
+                window.SetOverlayWindow(_transparentOverlayWindow);
+            }
+
+            window.Closed += OnFusedComponentLibraryWindowClosed;
+            window.Show();
+            if (centerInWorkArea)
+            {
+                window.CenterInWorkArea(_transparentOverlayWindow);
+            }
+
+            window.Activate();
+        }
+        catch (Exception ex)
+        {
+            AppLogger.Warn("FusedDesktop", "Failed to open fused desktop component library.", ex);
+            ExitFusedDesktopEditModeFromUi(closeLibrary: true);
+        }
+    }
+
+    private void OnFusedComponentLibraryWindowClosed(object? sender, EventArgs e)
+    {
+        if (sender is not FusedDesktopComponentLibraryWindow window)
+        {
+            return;
+        }
+
+        window.Closed -= OnFusedComponentLibraryWindowClosed;
+        if (ReferenceEquals(_fusedComponentLibraryWindow, window))
+        {
+            _fusedComponentLibraryWindow = null;
+        }
+
+        if (!window.PreserveEditModeOnClose && !_isExitingFusedDesktopEditMode)
+        {
+            ExitFusedDesktopEditModeFromUi(closeLibrary: false);
+        }
+    }
+
+    private void ExitFusedDesktopEditModeFromUi(bool closeLibrary)
+    {
+        if (_isExitingFusedDesktopEditMode)
+        {
+            return;
+        }
+
+        _isExitingFusedDesktopEditMode = true;
+        try
+        {
+            if (closeLibrary && _fusedComponentLibraryWindow is { } libraryWindow)
+            {
+                _fusedComponentLibraryWindow = null;
+                libraryWindow.Closed -= OnFusedComponentLibraryWindowClosed;
+                libraryWindow.Close();
+            }
+
             try
             {
-                if (_fusedComponentLibraryWindow is { } existingWindow)
-                {
-                    if (!existingWindow.IsVisible)
-                    {
-                        existingWindow.Show();
-                    }
-
-                    existingWindow.Activate();
-                    return;
-                }
-
-                var fusedDesktopManager = FusedDesktopManagerServiceFactory.GetOrCreate();
-                fusedDesktopManager.EnterEditMode();
-
-                // 纭繚閫忔槑瑕嗙洊灞傜獥鍙ｅ瓨鍦ㄥ苟鏄剧ず
-                EnsureTransparentOverlayWindow();
-                if (_transparentOverlayWindow is not null && !_transparentOverlayWindow.IsVisible)
-                {
-                    _transparentOverlayWindow.Show();
-                }
-                
-                var window = new FusedDesktopComponentLibraryWindow();
-                _fusedComponentLibraryWindow = window;
-                
-                if (_transparentOverlayWindow is not null)
-                {
-                    window.SetOverlayWindow(_transparentOverlayWindow);
-                }
-                
-                window.Closed += (s, ev) =>
-                {
-                    if (_transparentOverlayWindow is not null)
-                    {
-                        // 瑙﹀彂鐢诲竷淇濆瓨锛屽苟闅愯棌鐢诲竷
-                        _transparentOverlayWindow.SaveLayoutAndHide();
-                    }
-                    
-                    // 璁╃鐞嗗櫒鏍规嵁宸插瓨鍌ㄧ殑鏈€鏂板揩鐓ч噸寤虹敓鎴愭墍鏈夊疄浣撳皬缁勪欢
-                    fusedDesktopManager.ExitEditMode();
-                    if (ReferenceEquals(_fusedComponentLibraryWindow, s))
-                    {
-                        _fusedComponentLibraryWindow = null;
-                    }
-                };
-
-                window.Show();
-                window.Activate();
+                _transparentOverlayWindow?.SaveLayoutAndHide();
             }
-            catch (Exception ex)
+            catch (Exception overlayEx)
             {
-                AppLogger.Warn("FusedDesktop", "Failed to open fused desktop component library.", ex);
-                try
-                {
-                    _transparentOverlayWindow?.SaveLayoutAndHide();
-                }
-                catch (Exception overlayEx)
-                {
-                    AppLogger.Warn("FusedDesktop", "Failed to hide fused desktop overlay after library open failure.", overlayEx);
-                }
-
-                try
-                {
-                    FusedDesktopManagerServiceFactory.GetOrCreate().ExitEditMode();
-                }
-                catch (Exception exitEx)
-                {
-                    AppLogger.Warn("FusedDesktop", "Failed to exit edit mode after library open failure.", exitEx);
-                }
-
-                _fusedComponentLibraryWindow = null;
+                AppLogger.Warn("FusedDesktop", "Failed to hide fused desktop overlay.", overlayEx);
             }
-        }, DispatcherPriority.Send);
+
+            try
+            {
+                FusedDesktopManagerServiceFactory.GetOrCreate().ExitEditMode();
+            }
+            catch (Exception exitEx)
+            {
+                AppLogger.Warn("FusedDesktop", "Failed to exit fused desktop edit mode.", exitEx);
+            }
+        }
+        finally
+        {
+            _isExitingFusedDesktopEditMode = false;
+        }
     }
 
     private void DisableAvaloniaDataAnnotationValidation()
@@ -945,6 +991,14 @@ public partial class App : Application
             {
                 RestoreOrCreateMainWindow(showSingleInstanceNotice: false, source: "TransparentOverlay");
             };
+            _transparentOverlayWindow.ExitEditRequested += (s, e) =>
+            {
+                ExitFusedDesktopEditModeFromUi(closeLibrary: true);
+            };
+            _transparentOverlayWindow.RestoreComponentLibraryRequested += (s, e) =>
+            {
+                OpenFusedDesktopComponentLibraryFromUi(centerInWorkArea: true);
+            };
         }
     }
 
@@ -1217,7 +1271,7 @@ public partial class App : Application
 
         try
         {
-            HostUpdateWorkflowServiceProvider.GetOrCreate().TryApplyPendingUpdateOnExit();
+            HostUpdateOrchestratorProvider.GetOrCreate().TryApplyOnExit();
         }
         catch (Exception ex)
         {

LanMountainDesktop/DesktopEditing/FusedDesktopEditGridAdapter.cs

@@ -0,0 +1,73 @@
+using System;
+using Avalonia;
+using LanMountainDesktop.Services;
+using LanMountainDesktop.Services.Settings;
+
+namespace LanMountainDesktop.DesktopEditing;
+
+internal readonly record struct FusedDesktopEditGridContext(
+    DesktopGridGeometry Geometry,
+    DesktopGridMetrics Metrics)
+{
+    public bool IsValid => Geometry.IsValid && Metrics.CellSize > 0;
+}
+
+internal sealed class FusedDesktopEditGridAdapter
+{
+    private const int MinShortSideCells = 6;
+    private const int MaxShortSideCells = 96;
+    private const int DefaultShortSideCells = 12;
+    private const int MinEdgeInsetPercent = 0;
+    private const int MaxEdgeInsetPercent = 30;
+
+    private readonly ISettingsFacadeService _settingsFacade;
+
+    public FusedDesktopEditGridAdapter(ISettingsFacadeService settingsFacade)
+    {
+        _settingsFacade = settingsFacade;
+    }
+
+    public bool TryCreate(Size viewportSize, out FusedDesktopEditGridContext context)
+    {
+        context = default;
+        if (viewportSize.Width <= 1 || viewportSize.Height <= 1)
+        {
+            return false;
+        }
+
+        var state = _settingsFacade.Grid.Get();
+        var shortSideCells = Math.Clamp(
+            state.ShortSideCells > 0 ? state.ShortSideCells : DefaultShortSideCells,
+            MinShortSideCells,
+            MaxShortSideCells);
+        var spacingPreset = _settingsFacade.Grid.NormalizeSpacingPreset(state.SpacingPreset);
+        var gapRatio = _settingsFacade.Grid.ResolveGapRatio(spacingPreset);
+        var edgeInsetPercent = Math.Clamp(state.EdgeInsetPercent, MinEdgeInsetPercent, MaxEdgeInsetPercent);
+        var edgeInset = _settingsFacade.Grid.CalculateEdgeInset(
+            viewportSize.Width,
+            viewportSize.Height,
+            shortSideCells,
+            edgeInsetPercent);
+        var metrics = _settingsFacade.Grid.CalculateGridMetrics(
+            viewportSize.Width,
+            viewportSize.Height,
+            shortSideCells,
+            gapRatio,
+            edgeInset);
+
+        if (metrics.CellSize <= 0 || metrics.ColumnCount <= 0 || metrics.RowCount <= 0)
+        {
+            return false;
+        }
+
+        var geometry = new DesktopGridGeometry(
+            Origin: new Point(metrics.EdgeInsetPx, metrics.EdgeInsetPx),
+            CellSize: metrics.CellSize,
+            CellGap: metrics.GapPx,
+            ColumnCount: metrics.ColumnCount,
+            RowCount: metrics.RowCount);
+
+        context = new FusedDesktopEditGridContext(geometry, metrics);
+        return context.IsValid;
+    }
+}

LanMountainDesktop/Models/FusedDesktopLayoutSnapshot.cs

@@ -38,6 +38,14 @@ public sealed class FusedDesktopComponentPlacementSnapshot
     /// </summary>
     public double Height { get; set; } = 200;
 
+    public int? GridRow { get; set; }
+
+    public int? GridColumn { get; set; }
+
+    public int? GridWidthCells { get; set; }
+
+    public int? GridHeightCells { get; set; }
+    
     /// <summary>
     /// Z-Index（用于控制组件层叠顺序）
     /// </summary>
@@ -61,6 +69,10 @@ public sealed class FusedDesktopComponentPlacementSnapshot
             Y = Y,
             Width = Width,
             Height = Height,
+            GridRow = GridRow,
+            GridColumn = GridColumn,
+            GridWidthCells = GridWidthCells,
+            GridHeightCells = GridHeightCells,
             ZIndex = ZIndex,
             IsLocked = IsLocked
         };

LanMountainDesktop/Services/Settings/SettingsDomainServices.cs

@@ -847,7 +847,6 @@ internal sealed class UpdateSettingsService : IUpdateSettingsService, IDisposabl
             snapshot,
             changedKeys:
             [
-                nameof(AppSettingsSnapshot.IncludePrereleaseUpdates),
                 nameof(AppSettingsSnapshot.IncludePrereleaseUpdates),
                 nameof(AppSettingsSnapshot.UpdateChannel),
                 nameof(AppSettingsSnapshot.UpdateMode),

LanMountainDesktop/Services/Update/DeploymentLockService.cs

@@ -0,0 +1,52 @@
+using System;
+using System.IO;
+using System.Text.Json;
+using LanMountainDesktop.Shared.Contracts.Update;
+
+namespace LanMountainDesktop.Services.Update;
+
+internal static class DeploymentLockService
+{
+    private static readonly JsonSerializerOptions JsonOptions = new()
+    {
+        WriteIndented = true
+    };
+
+    public static void WriteLock(string launcherRoot, DeploymentLock deploymentLock)
+    {
+        var lockPath = UpdatePaths.GetDeploymentLockPath(launcherRoot);
+        Directory.CreateDirectory(Path.GetDirectoryName(lockPath)!);
+        var tempPath = lockPath + ".tmp";
+        File.WriteAllText(tempPath, JsonSerializer.Serialize(deploymentLock, JsonOptions));
+        File.Move(tempPath, lockPath, true);
+    }
+
+    public static DeploymentLock? ReadLock(string launcherRoot)
+    {
+        var lockPath = UpdatePaths.GetDeploymentLockPath(launcherRoot);
+        if (!File.Exists(lockPath))
+        {
+            return null;
+        }
+
+        try
+        {
+            var json = File.ReadAllText(lockPath);
+            return JsonSerializer.Deserialize<DeploymentLock>(json);
+        }
+        catch (Exception ex)
+        {
+            AppLogger.Warn("UpdateLock", $"Failed to parse deployment lock: {ex.Message}");
+            return null;
+        }
+    }
+
+    public static void ClearLock(string launcherRoot)
+    {
+        var lockPath = UpdatePaths.GetDeploymentLockPath(launcherRoot);
+        if (File.Exists(lockPath))
+        {
+            File.Delete(lockPath);
+        }
+    }
+}

LanMountainDesktop/Services/Update/UpdateDownloadEngine.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -77,7 +78,7 @@ internal sealed class UpdateDownloadEngine
 
         var totalFiles = downloadableFiles.Count + 2;
         var completedFiles = 2;
-        var seenHashes = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+        var seenHashes = new ConcurrentDictionary<string, byte>(StringComparer.OrdinalIgnoreCase);
         var semaphore = new SemaphoreSlim(Math.Max(1, maxConcurrency), Math.Max(1, maxConcurrency));
         var errors = new List<string>();
         long totalBytes = downloadableFiles.Sum(f => f.Size);
@@ -89,7 +90,7 @@ internal sealed class UpdateDownloadEngine
             await semaphore.WaitAsync(ct);
             try
             {
-                if (!seenHashes.Add(entry.Sha256))
+                if (!seenHashes.TryAdd(entry.Sha256, 0))
                 {
                     lock (lockObj)
                     {
@@ -146,6 +147,20 @@ internal sealed class UpdateDownloadEngine
                         {
                             AppLogger.Warn("UpdateDownloadEngine",
                                 $"Object {entry.Path} hash mismatch after download. Expected: {entry.Sha256}, Actual: {actualHash}");
+                            SafeDeleteFile(objectPath);
+
+                            if (attempt < MaxRetryAttempts)
+                            {
+                                await Task.Delay(RetryDelayMs * attempt, ct);
+                                continue;
+                            }
+
+                            lock (lockObj)
+                            {
+                                errors.Add($"Hash mismatch for {entry.Path}: expected {entry.Sha256}, actual {actualHash}");
+                            }
+
+                            return;
                         }
 
                         lock (lockObj)
@@ -274,7 +289,7 @@ internal sealed class UpdateDownloadEngine
 
             if (result.Success)
             {
-                bool hashVerified;
+                bool hashVerified = true;
                 if (!string.IsNullOrWhiteSpace(mirror.Sha256))
                 {
                     var actualHash = await ComputeFileSha256Async(destinationPath, ct);
@@ -283,12 +298,17 @@ internal sealed class UpdateDownloadEngine
                     {
                         AppLogger.Warn("UpdateDownloadEngine",
                             $"Full installer hash mismatch. Expected: {mirror.Sha256}, Actual: {actualHash}");
+                        SafeDeleteFile(destinationPath);
+
+                        if (attempt < MaxRetryAttempts)
+                        {
+                            await Task.Delay(RetryDelayMs * attempt, ct);
+                            continue;
+                        }
+
+                        return new DownloadResult(false, null, $"Full installer hash mismatch. Expected: {mirror.Sha256}, Actual: {actualHash}", false);
                     }
                 }
-                else
-                {
-                    hashVerified = false;
-                }
 
                 AppLogger.Info("UpdateDownloadEngine", $"Full installer downloaded to {destinationPath}");
                 return new DownloadResult(true, destinationPath, null, hashVerified);
@@ -374,6 +394,20 @@ internal sealed class UpdateDownloadEngine
         return Convert.ToHexString(hash).ToLowerInvariant();
     }
 
+    private static void SafeDeleteFile(string filePath)
+    {
+        try
+        {
+            if (File.Exists(filePath))
+            {
+                File.Delete(filePath);
+            }
+        }
+        catch
+        {
+        }
+    }
+
     private static string ComputeStringSha256(string content)
     {
         using var hasher = SHA256.Create();

LanMountainDesktop/Services/Update/UpdateInstallGateway.cs

@@ -2,6 +2,7 @@ using System;
 using System.ComponentModel;
 using System.Diagnostics;
 using System.IO;
+using System.Linq;
 using System.Runtime.InteropServices;
 using System.Threading;
 using System.Threading.Tasks;
@@ -9,7 +10,7 @@ using LanMountainDesktop.Shared.Contracts.Update;
 
 namespace LanMountainDesktop.Services.Update;
 
-public sealed record InstallResult(bool Success, string? ErrorMessage, bool UserCancelledElevation);
+public sealed record InstallResult(bool Success, string? ErrorMessage, bool UserCancelledElevation, string? ErrorCode = null);
 
 internal sealed class UpdateInstallGateway
 {
@@ -31,12 +32,17 @@ internal sealed class UpdateInstallGateway
                 0,
                 0));
 
+            if (!VerifyDeploymentLock(payloadKind, launcherRoot, out var lockErrorCode, out var lockError))
+            {
+                return new InstallResult(false, lockError, false, lockErrorCode);
+            }
+
             if (payloadKind is UpdatePayloadKind.DeltaPlonds or UpdatePayloadKind.DeltaLegacy)
             {
                 var launched = LaunchLauncherForApplyUpdate(launcherRoot);
                 if (!launched)
                 {
-                    return new InstallResult(false, "Failed to launch Launcher for delta update application.", false);
+                    return new InstallResult(false, "Failed to launch Launcher for delta update application.", false, "apply_failed");
                 }
 
                 progress?.Report(new InstallProgressReport(
@@ -50,10 +56,10 @@ internal sealed class UpdateInstallGateway
                 return new InstallResult(true, null, false);
             }
 
-            var installerPath = FindPendingInstaller(launcherRoot);
+            var installerPath = FindPendingInstaller(launcherRoot, payloadKind, ct);
             if (installerPath is null)
             {
-                return new InstallResult(false, "No pending installer found.", false);
+                return new InstallResult(false, "No pending installer found.", false, "staging_incomplete");
             }
 
             var installerLaunched = LaunchFullInstaller(installerPath);
@@ -83,6 +89,43 @@ internal sealed class UpdateInstallGateway
         }
     }
 
+    private static bool VerifyDeploymentLock(UpdatePayloadKind payloadKind, string launcherRoot, out string? errorCode, out string? error)
+    {
+        errorCode = null;
+        error = null;
+        var deploymentLock = DeploymentLockService.ReadLock(launcherRoot);
+        if (deploymentLock is null)
+        {
+            errorCode = "lock_conflict";
+            error = "Deployment lock is missing. Please redownload the update.";
+            return false;
+        }
+
+        if (deploymentLock.SchemaVersion != 1)
+        {
+            errorCode = "lock_conflict";
+            error = "Deployment lock schema is unsupported. Please redownload the update.";
+            return false;
+        }
+
+        var expectedKind = payloadKind is UpdatePayloadKind.DeltaLegacy or UpdatePayloadKind.DeltaPlonds ? "delta" : "full";
+        if (!string.Equals(deploymentLock.Kind, expectedKind, StringComparison.OrdinalIgnoreCase))
+        {
+            errorCode = "lock_conflict";
+            error = "Deployment lock payload type mismatch. Please redownload the update.";
+            return false;
+        }
+
+        if (string.IsNullOrWhiteSpace(deploymentLock.PayloadPath) || !File.Exists(deploymentLock.PayloadPath))
+        {
+            errorCode = "staging_incomplete";
+            error = "Deployment lock payload path is missing. Please redownload the update.";
+            return false;
+        }
+
+        return true;
+    }
+
     private bool LaunchLauncherForApplyUpdate(string launcherRoot)
     {
         try
@@ -145,15 +188,27 @@ internal sealed class UpdateInstallGateway
         }
     }
 
-    private static string? FindPendingInstaller(string launcherRoot)
+    private static string? FindPendingInstaller(string launcherRoot, UpdatePayloadKind payloadKind, CancellationToken ct)
     {
+        ct.ThrowIfCancellationRequested();
+
         var incomingDir = UpdatePaths.GetIncomingDirectory(launcherRoot);
         if (!Directory.Exists(incomingDir))
         {
             return null;
         }
 
-        var executables = Directory.GetFiles(incomingDir, "*.exe");
-        return executables.Length > 0 ? executables[0] : null;
+        var executables = new DirectoryInfo(incomingDir)
+            .EnumerateFiles("*.exe", SearchOption.TopDirectoryOnly)
+            .OrderByDescending(file => file.LastWriteTimeUtc)
+            .ThenBy(file => file.Name, StringComparer.OrdinalIgnoreCase)
+            .ToArray();
+
+        if (executables.Length == 0)
+        {
+            return null;
+        }
+
+        return executables[0].FullName;
     }
 }

LanMountainDesktop/Services/Update/UpdateOrchestrator.cs

@@ -9,6 +9,34 @@ using SettingsUpdateSettingsState = LanMountainDesktop.Services.Settings.UpdateS
 
 namespace LanMountainDesktop.Services.Update;
 
+internal static class HostUpdateOrchestratorProvider
+{
+    private static readonly object Gate = new();
+    private static UpdateOrchestrator? _instance;
+
+    public static UpdateOrchestrator GetOrCreate()
+    {
+        lock (Gate)
+        {
+            if (_instance is not null)
+            {
+                return _instance;
+            }
+
+            var settingsFacade = HostSettingsFacadeProvider.GetOrCreate();
+            var githubProvider = new GithubReleaseManifestProvider("wwiinnddyy", "LanMountainDesktop");
+            var staticProvider = new PlondsApiManifestProvider("https://api.classisland.tech");
+            var compositeProvider = new CompositeManifestProvider(staticProvider, githubProvider);
+            var httpClient = new System.Net.Http.HttpClient { Timeout = TimeSpan.FromSeconds(30) };
+            var downloadEngine = new UpdateDownloadEngine(compositeProvider, new ResumableDownloadService(httpClient));
+            var installGateway = new UpdateInstallGateway();
+            var stateStore = new UpdateStateStore(settingsFacade);
+            _instance = new UpdateOrchestrator(compositeProvider, downloadEngine, installGateway, stateStore);
+            return _instance;
+        }
+    }
+}
+
 public sealed class UpdateOrchestrator : IDisposable
 {
     private readonly IUpdateManifestProvider _manifestProvider;
@@ -16,6 +44,8 @@ public sealed class UpdateOrchestrator : IDisposable
     private readonly UpdateInstallGateway _installGateway;
     private readonly UpdateStateStore _stateStore;
     private readonly SemaphoreSlim _operationGate = new(1, 1);
+    private readonly object _cancellationSync = new();
+    private CancellationTokenSource? _activeOperationCts;
     private bool _disposed;
 
     internal UpdateOrchestrator(
@@ -40,9 +70,29 @@ public sealed class UpdateOrchestrator : IDisposable
     public event Action<UpdatePhase>? PhaseChanged;
     public event Action<UpdateProgressReport>? ProgressChanged;
 
+    private CancellationToken RegisterOperationCancellation(CancellationToken ct)
+    {
+        lock (_cancellationSync)
+        {
+            _activeOperationCts?.Dispose();
+            _activeOperationCts = CancellationTokenSource.CreateLinkedTokenSource(ct);
+            return _activeOperationCts.Token;
+        }
+    }
+
+    private void ClearOperationCancellation()
+    {
+        lock (_cancellationSync)
+        {
+            _activeOperationCts?.Dispose();
+            _activeOperationCts = null;
+        }
+    }
+
     public async Task<UpdateCheckReport> CheckAsync(CancellationToken ct)
     {
         await _operationGate.WaitAsync(ct);
+        var operationToken = RegisterOperationCancellation(ct);
         try
         {
             if (!CurrentPhase.CanCheck())
@@ -59,9 +109,21 @@ public sealed class UpdateOrchestrator : IDisposable
             var currentVersionText = _stateStore.GetSettings().PendingUpdateVersion
                 ?? AppVersionProvider.ResolveForCurrentProcess().Version;
 
-            if (!Version.TryParse(currentVersionText, out var currentVersion))
+            if (!TryParseVersion(currentVersionText, out var currentVersion))
             {
-                currentVersion = new Version(0, 0, 0);
+                _stateStore.TransitionTo(UpdatePhase.Failed);
+                _stateStore.RecordFailure($"Invalid current version text: {currentVersionText}");
+                return new UpdateCheckReport(
+                    false,
+                    null,
+                    currentVersionText,
+                    null,
+                    null,
+                    null,
+                    null,
+                    null,
+                    null,
+                    $"Invalid current version text: {currentVersionText}");
             }
 
             UpdateManifest? manifest;
@@ -71,7 +133,7 @@ public sealed class UpdateOrchestrator : IDisposable
                     channel,
                     LanMountainDesktop.Services.PlondsStaticUpdateService.ResolveCurrentPlatform(),
                     currentVersion,
-                    ct);
+                    operationToken);
             }
             catch (OperationCanceledException)
             {
@@ -114,6 +176,7 @@ public sealed class UpdateOrchestrator : IDisposable
         }
         finally
         {
+            ClearOperationCancellation();
             _operationGate.Release();
         }
     }
@@ -121,9 +184,10 @@ public sealed class UpdateOrchestrator : IDisposable
     public async Task<DownloadResult> DownloadAsync(CancellationToken ct)
     {
         await _operationGate.WaitAsync(ct);
+        var operationToken = RegisterOperationCancellation(ct);
         try
         {
-            if (!CurrentPhase.CanDownload())
+            if (CurrentPhase is not (UpdatePhase.Checked or UpdatePhase.PausedDownloading))
             {
                 return new DownloadResult(false, null, $"Cannot download in phase {CurrentPhase}.", false);
             }
@@ -168,7 +232,7 @@ public sealed class UpdateOrchestrator : IDisposable
                         objectsDir,
                         maxThreads,
                         downloadProgress,
-                        ct);
+                        operationToken);
                 }
                 else
                 {
@@ -183,7 +247,7 @@ public sealed class UpdateOrchestrator : IDisposable
                         destinationPath,
                         maxThreads,
                         downloadProgress,
-                        ct);
+                        operationToken);
                 }
 
                 if (result.Success)
@@ -196,9 +260,19 @@ public sealed class UpdateOrchestrator : IDisposable
                         PendingUpdateInstallerPath = result.FilePath,
                         PendingUpdateVersion = manifest.ToVersion,
                         PendingUpdatePublishedAtUtcMs = manifest.PublishedAt.ToUnixTimeMilliseconds(),
-                        PendingUpdateSha256 = null
+                        PendingUpdateSha256 = null,
+                        LastUpdateCheckUtcMs = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds()
                     });
 
+                    var payloadKind = manifest.IsDelta ? "delta" : "full";
+                    DeploymentLockService.WriteLock(launcherRoot, new DeploymentLock(
+                        SchemaVersion: 1,
+                        Kind: payloadKind,
+                        TargetVersion: manifest.ToVersion,
+                        PayloadPath: result.FilePath ?? string.Empty,
+                        PayloadSha256: null,
+                        CreatedAtUtc: DateTimeOffset.UtcNow));
+
                     AppLogger.Info("UpdateOrchestrator", $"Update downloaded successfully: {manifest.ToVersion}");
                 }
                 else
@@ -211,7 +285,11 @@ public sealed class UpdateOrchestrator : IDisposable
             }
             catch (OperationCanceledException)
             {
-                _stateStore.TransitionTo(UpdatePhase.Idle);
+                if (CurrentPhase != UpdatePhase.PausedDownloading)
+                {
+                    _stateStore.TransitionTo(UpdatePhase.Idle);
+                }
+
                 throw;
             }
             catch (Exception ex)
@@ -223,6 +301,7 @@ public sealed class UpdateOrchestrator : IDisposable
         }
         finally
         {
+            ClearOperationCancellation();
             _operationGate.Release();
         }
     }
@@ -230,17 +309,18 @@ public sealed class UpdateOrchestrator : IDisposable
     public async Task<InstallResult> InstallAsync(CancellationToken ct)
     {
         await _operationGate.WaitAsync(ct);
+        var operationToken = RegisterOperationCancellation(ct);
         try
         {
             if (!CurrentPhase.CanInstall())
             {
-                return new InstallResult(false, $"Cannot install in phase {CurrentPhase}.", false);
+                return new InstallResult(false, $"Cannot install in phase {CurrentPhase}.", false, "invalid_phase");
             }
 
             var manifest = _stateStore.PendingManifest;
             if (manifest is null)
             {
-                return new InstallResult(false, "No manifest available for install.", false);
+                return new InstallResult(false, "No manifest available for install.", false, "staging_incomplete");
             }
 
             _stateStore.TransitionTo(UpdatePhase.Installing);
@@ -264,7 +344,7 @@ public sealed class UpdateOrchestrator : IDisposable
                     manifest.Kind,
                     launcherRoot,
                     installProgress,
-                    ct);
+                    operationToken);
 
                 if (result.Success)
                 {
@@ -282,18 +362,23 @@ public sealed class UpdateOrchestrator : IDisposable
             }
             catch (OperationCanceledException)
             {
-                _stateStore.TransitionTo(UpdatePhase.Failed);
+                if (CurrentPhase != UpdatePhase.PausedInstalling)
+                {
+                    _stateStore.TransitionTo(UpdatePhase.Idle);
+                }
+
                 throw;
             }
             catch (Exception ex)
             {
                 _stateStore.TransitionTo(UpdatePhase.Failed);
                 _stateStore.RecordFailure(ex.Message);
-                return new InstallResult(false, ex.Message, false);
+                return new InstallResult(false, ex.Message, false, "install_exception");
             }
         }
         finally
         {
+            ClearOperationCancellation();
             _operationGate.Release();
         }
     }
@@ -301,8 +386,11 @@ public sealed class UpdateOrchestrator : IDisposable
     public async Task RollbackAsync(CancellationToken ct)
     {
         await _operationGate.WaitAsync(ct);
+        var operationToken = RegisterOperationCancellation(ct);
         try
         {
+            operationToken.ThrowIfCancellationRequested();
+
             if (!CurrentPhase.CanRollback())
             {
                 return;
@@ -330,6 +418,11 @@ public sealed class UpdateOrchestrator : IDisposable
 
                 _stateStore.TransitionTo(UpdatePhase.RolledBack);
             }
+            catch (OperationCanceledException)
+            {
+                _stateStore.TransitionTo(UpdatePhase.Idle);
+                throw;
+            }
             catch (Exception ex)
             {
                 AppLogger.Warn("UpdateOrchestrator", $"Rollback failed: {ex.Message}");
@@ -338,21 +431,86 @@ public sealed class UpdateOrchestrator : IDisposable
         }
         finally
         {
+            ClearOperationCancellation();
             _operationGate.Release();
         }
     }
 
-    public async Task CancelAsync()
+    public Task CancelAsync()
     {
-        if (!CurrentPhase.IsBusy())
+        if (!CurrentPhase.CanCancel())
         {
-            return;
+            return Task.CompletedTask;
+        }
+
+        lock (_cancellationSync)
+        {
+            _activeOperationCts?.Cancel();
         }
 
         _stateStore.TransitionTo(UpdatePhase.Idle);
-        _stateStore.PendingManifest = null;
-        AppLogger.Info("UpdateOrchestrator", "Update operation cancelled.");
-        await Task.CompletedTask;
+
+        var launcherRoot = UpdatePaths.ResolveLauncherRoot(AppContext.BaseDirectory);
+        CleanupIncomingArtifacts(launcherRoot);
+        DeploymentLockService.ClearLock(launcherRoot);
+
+        var state = _stateStore.GetSettings();
+        _stateStore.SaveSettings(state with
+        {
+            PendingUpdateInstallerPath = null,
+            PendingUpdateVersion = null,
+            PendingUpdateSha256 = null
+        });
+
+        AppLogger.Info("UpdateOrchestrator", "Cancellation requested for active update operation.");
+        return Task.CompletedTask;
+    }
+
+    public Task PauseAsync()
+    {
+        if (!CurrentPhase.CanPause())
+        {
+            return Task.CompletedTask;
+        }
+
+        var pausedPhase = CurrentPhase switch
+        {
+            UpdatePhase.Downloading => UpdatePhase.PausedDownloading,
+            UpdatePhase.Installing => UpdatePhase.PausedInstalling,
+            _ => UpdatePhase.Idle
+        };
+
+        _stateStore.TransitionTo(pausedPhase);
+
+        lock (_cancellationSync)
+        {
+            _activeOperationCts?.Cancel();
+        }
+
+        AppLogger.Info("UpdateOrchestrator", $"Pause requested in phase {pausedPhase}.");
+        return Task.CompletedTask;
+    }
+
+    public async Task<DownloadResult> ResumeAsync(CancellationToken ct)
+    {
+        return CurrentPhase switch
+        {
+            UpdatePhase.PausedDownloading => await DownloadAsync(ct),
+            UpdatePhase.PausedInstalling => await ResumeInstallAsync(ct),
+            _ => new DownloadResult(false, null, $"Cannot resume in phase {CurrentPhase}.", false)
+        };
+    }
+
+    private async Task<DownloadResult> ResumeInstallAsync(CancellationToken ct)
+    {
+        _stateStore.TransitionTo(UpdatePhase.Recovering);
+        var installResult = await InstallAsync(ct);
+        if (installResult.Success)
+        {
+            return new DownloadResult(true, null, null, false);
+        }
+
+        return new DownloadResult(false, null, installResult.ErrorMessage ?? installResult.ErrorCode ?? "Install resume failed.", false);
     }
 
     public async Task AutoCheckIfEnabledAsync(CancellationToken ct)
@@ -458,6 +616,77 @@ public sealed class UpdateOrchestrator : IDisposable
         }
     }
 
+    private static void CleanupIncomingArtifacts(string launcherRoot)
+    {
+        var incomingDir = UpdatePaths.GetIncomingDirectory(launcherRoot);
+
+        foreach (var path in new[]
+                 {
+                     Path.Combine(incomingDir, UpdatePaths.GetLegacyFileMapName()),
+                     Path.Combine(incomingDir, UpdatePaths.GetLegacySignatureName()),
+                     Path.Combine(incomingDir, UpdatePaths.GetLegacyArchiveName()),
+                     Path.Combine(incomingDir, UpdatePaths.GetPlondsFileMapName()),
+                     Path.Combine(incomingDir, UpdatePaths.GetPlondsSignatureName()),
+                     Path.Combine(incomingDir, UpdatePaths.GetPlondsUpdateMetadataName()),
+                     UpdatePaths.GetDownloadMarkerPath(launcherRoot)
+                 })
+        {
+            try
+            {
+                if (File.Exists(path))
+                {
+                    File.Delete(path);
+                }
+            }
+            catch
+            {
+            }
+        }
+
+        try
+        {
+            var objectsDir = UpdatePaths.GetObjectsDirectory(launcherRoot);
+            if (Directory.Exists(objectsDir))
+            {
+                Directory.Delete(objectsDir, true);
+            }
+        }
+        catch
+        {
+        }
+    }
+
+    private static bool TryParseVersion(string? value, out Version version)
+    {
+        version = new Version(0, 0, 0);
+
+        if (string.IsNullOrWhiteSpace(value))
+        {
+            return false;
+        }
+
+        var normalized = value.Trim().TrimStart('v', 'V');
+        var dashIndex = normalized.IndexOf('-');
+        if (dashIndex >= 0)
+        {
+            normalized = normalized[..dashIndex];
+        }
+
+        var plusIndex = normalized.IndexOf('+');
+        if (plusIndex >= 0)
+        {
+            normalized = normalized[..plusIndex];
+        }
+
+        if (!Version.TryParse(normalized, out var parsed))
+        {
+            return false;
+        }
+
+        version = new Version(parsed.Major, parsed.Minor, Math.Max(0, parsed.Build), Math.Max(0, parsed.Revision));
+        return true;
+    }
+
     private void OnPhaseChanged(UpdatePhase phase)
     {
         PhaseChanged?.Invoke(phase);
@@ -478,6 +707,11 @@ public sealed class UpdateOrchestrator : IDisposable
         _disposed = true;
         _stateStore.PhaseChanged -= OnPhaseChanged;
         _stateStore.ProgressChanged -= OnProgressChanged;
+        lock (_cancellationSync)
+        {
+            _activeOperationCts?.Dispose();
+            _activeOperationCts = null;
+        }
         _operationGate.Dispose();
     }
 }

LanMountainDesktop/Services/WindowPassthroughService.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.Collections.Generic;
 using System.Runtime.InteropServices;
 using Avalonia;
@@ -7,9 +6,6 @@ using Avalonia.Controls;
 
 namespace LanMountainDesktop.Services;
 
-/// <summary>
-/// 窗口置底服务接口
-/// </summary>
 public interface IWindowBottomMostService
 {
     void SetupBottomMost(Window window);
@@ -17,30 +13,13 @@ public interface IWindowBottomMostService
     bool IsBottomMostSupported { get; }
 }
 
-/// <summary>
-/// 区域级穿透服务接口 - 使用 WM_NCHITTEST 实现
-/// </summary>
 public interface IRegionPassthroughService
 {
-    /// <summary>
-    /// 设置窗口的可交互区域
-    /// </summary>
     void SetInteractiveRegions(Window window, IReadOnlyList<Rect> interactiveRegions);
-    
-    /// <summary>
-    /// 清除所有可交互区域
-    /// </summary>
     void ClearInteractiveRegions(Window window);
-    
-    /// <summary>
-    /// 获取当前平台是否支持区域级穿透
-    /// </summary>
     bool IsRegionPassthroughSupported { get; }
 }
 
-/// <summary>
-/// 窗口置底服务工厂
-/// </summary>
 public static class WindowBottomMostServiceFactory
 {
     private static IWindowBottomMostService? _instance;
@@ -57,9 +36,6 @@ public static class WindowBottomMostServiceFactory
     }
 }
 
-/// <summary>
-/// 区域级穿透服务工厂
-/// </summary>
 public static class RegionPassthroughServiceFactory
 {
     private static IRegionPassthroughService? _instance;
@@ -76,103 +52,83 @@ public static class RegionPassthroughServiceFactory
     }
 }
 
-/// <summary>
-/// Windows 平台窗口置底服务
-/// </summary>
 internal sealed class WindowsWindowBottomMostService : IWindowBottomMostService
 {
+    private const int GWL_STYLE = -16;
     private const int GWL_EXSTYLE = -20;
-    private const int GWL_HWNDPARENT = -8;
     private const int GWLP_WNDPROC = -4;
-    private const int WS_EX_TOOLWINDOW = 0x00000080;
-    private const int WS_EX_APPWINDOW = 0x00040000;
-    private const int WS_EX_NOACTIVATE = 0x08000000;
-    private const int WS_EX_LAYERED = 0x00080000;
+
+    private const long WS_CHILD = 0x40000000L;
+    private const long WS_POPUP = 0x80000000L;
+    private const long WS_CAPTION = 0x00C00000L;
+    private const long WS_THICKFRAME = 0x00040000L;
+    private const long WS_MINIMIZEBOX = 0x00020000L;
+    private const long WS_MAXIMIZEBOX = 0x00010000L;
+    private const long WS_SYSMENU = 0x00080000L;
+
+    private const long WS_EX_TOOLWINDOW = 0x00000080L;
+    private const long WS_EX_APPWINDOW = 0x00040000L;
+    private const long WS_EX_NOACTIVATE = 0x08000000L;
+    private const long WS_EX_LAYERED = 0x00080000L;
+
     private const uint SWP_NOSIZE = 0x0001;
     private const uint SWP_NOMOVE = 0x0002;
     private const uint SWP_NOACTIVATE = 0x0010;
-    private const int WM_WINDOWPOSCHANGING = 0x0046;
+    private const uint SWP_SHOWWINDOW = 0x0040;
+
     private const int WM_NCHITTEST = 0x0084;
-    private const int WM_ACTIVATEAPP = 0x001C;  // 【新增】应用激活消息
     private const int HTTRANSPARENT = -1;
     private const int HTCLIENT = 1;
 
+    private const int MONITOR_DEFAULTTONEAREST = 2;
+    private const int MDT_EFFECTIVE_DPI = 0;
+
+    private static readonly IntPtr HWND_TOP = IntPtr.Zero;
     private static readonly IntPtr HWND_BOTTOM = new(1);
-    private static readonly Dictionary<IntPtr, bool> _bottomMostWindows = new();
+    private static readonly object _staticLock = new();
+    private static readonly object _timerLock = new();
+
+    private static readonly Dictionary<IntPtr, DesktopWindowState> _desktopWindows = new();
     private static readonly Dictionary<IntPtr, IntPtr> _originalWndProcs = new();
     private static readonly Dictionary<IntPtr, List<Rect>> _interactiveRegions = new();
-    
-    // 记录每个窗口的屏幕原点（窗口左上角的屏幕坐标），用于将 WM_NCHITTEST 屏幕坐标转成窗口相对坐标
     private static readonly Dictionary<IntPtr, Point> _windowScreenOrigins = new();
-    private static readonly object _staticLock = new();
-    
-    // 【修复问题1】静态持有委托引用，防止 GC 回收导致 CallbackOnCollectedDelegate 崩溃
-    private static WndProcDelegate? _wndProcDelegate;
-    
-    // 【修复问题2】记录每个窗口的 DPI 缩放比例
     private static readonly Dictionary<IntPtr, double> _windowDpiScales = new();
 
-    // 【修复问题5】Z 轴竞争优化 - 记录上次置底时间，避免频繁操作
-    private static readonly Dictionary<IntPtr, long> _lastSendToBottomTime = new();
-    private const long MinSendToBottomIntervalMs = 100;  // 【修复置底问题】降低到 100ms，提高响应速度
-    
-    // 【新增】定时器定期强制置底
-    private static System.Timers.Timer? _keepBottomTimer;
-    private static readonly object _timerLock = new();
+    private static WndProcDelegate? _wndProcDelegate;
+    private static System.Timers.Timer? _desktopHostMonitorTimer;
 
     public bool IsBottomMostSupported => true;
 
     public void SetupBottomMost(Window window)
     {
-        if (!OperatingSystem.IsWindows()) return;
-        
-        window.Opened += (s, e) =>
+        if (!OperatingSystem.IsWindows())
         {
-            var handle = GetWindowHandle(window);
-            if (handle == IntPtr.Zero) return;
+            return;
+        }
 
-            // 设置扩展样式
-            var exStyle = GetWindowLong(handle, GWL_EXSTYLE);
-            exStyle = (exStyle | WS_EX_TOOLWINDOW | WS_EX_NOACTIVATE | WS_EX_LAYERED) & ~WS_EX_APPWINDOW;
-            SetWindowLong(handle, GWL_EXSTYLE, exStyle);
-            
-            // 设置为桌面子窗口
-            SetAsDesktopChild(handle);
-            
-            // 注册置底状态 & 记录窗口屏幕原点
-            lock (_staticLock)
-            {
-                _bottomMostWindows[handle] = true;
-                _interactiveRegions[handle] = [];
-                UpdateWindowScreenOrigin(handle);
-                UpdateWindowDpiScale(handle);  // 【修复问题2】初始化 DPI 缩放
-            }
-            
-            // 注入消息钩子
-            InstallMessageHook(handle);
-            
-            // 初始置底
-            SendToBottomInternal(handle);
-            
-            // 【新增】启动定时器定期强制置底
-            StartKeepBottomTimer();
-            
-            AppLogger.Info("WindowBottomMost", $"Window setup as bottom-most: {handle}");
-        };
-        
-        window.Closed += (s, e) =>
+        var handle = GetWindowHandle(window);
+        if (handle != IntPtr.Zero)
         {
-            var handle = GetWindowHandle(window);
-            if (handle != IntPtr.Zero)
+            ApplyDesktopAttachment(handle, logSuccess: true);
+        }
+        else
+        {
+            window.Opened += (_, _) =>
             {
-                lock (_staticLock)
+                var openedHandle = GetWindowHandle(window);
+                if (openedHandle != IntPtr.Zero)
                 {
-                    _bottomMostWindows.Remove(handle);
-                    _originalWndProcs.Remove(handle);
-                    _interactiveRegions.Remove(handle);
-                    _windowScreenOrigins.Remove(handle);
-                    _windowDpiScales.Remove(handle);  // 【修复问题2】清理 DPI 缩放记录
+                    ApplyDesktopAttachment(openedHandle, logSuccess: true);
                 }
+            };
+        }
+
+        window.Closed += (_, _) =>
+        {
+            var closedHandle = GetWindowHandle(window);
+            if (closedHandle != IntPtr.Zero)
+            {
+                CleanupWindow(closedHandle);
             }
         };
     }
@@ -180,143 +136,212 @@ internal sealed class WindowsWindowBottomMostService : IWindowBottomMostService
     public void SendToBottom(Window window)
     {
         var handle = GetWindowHandle(window);
-        if (handle != IntPtr.Zero) SendToBottomInternal(handle);
-    }
-    
-    private static IntPtr GetWindowHandle(Window window)
-    {
-        try { return window.TryGetPlatformHandle()?.Handle ?? IntPtr.Zero; }
-        catch { return IntPtr.Zero; }
-    }
-    
-    private static void SendToBottomInternal(IntPtr handle)
-    {
-        SetWindowPos(handle, HWND_BOTTOM, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE);
-    }
-    
-    /// <summary>
-    /// 【新增】启动定时器定期强制置底所有窗口
-    /// </summary>
-    private static void StartKeepBottomTimer()
-    {
-        lock (_timerLock)
+        if (handle != IntPtr.Zero)
         {
-            if (_keepBottomTimer != null) return;
-            
-            _keepBottomTimer = new System.Timers.Timer(200);  // 每 200ms 检查一次
-            _keepBottomTimer.Elapsed += (s, e) =>
-            {
-                try
-                {
-                    lock (_staticLock)
-                    {
-                        foreach (var kvp in _bottomMostWindows)
-                        {
-                            if (kvp.Value)  // 如果标记为置底
-                            {
-                                SendToBottomInternal(kvp.Key);
-                            }
-                        }
-                    }
-                }
-                catch
-                {
-                    // 忽略定时器错误
-                }
-            };
-            _keepBottomTimer.Start();
+            ApplyDesktopAttachment(handle, logSuccess: false);
         }
     }
 
-    /// <summary>
-    /// 【新增】停止定时器
-    /// </summary>
-    private static void StopKeepBottomTimer()
+    internal static void SetInteractiveRegionsInternal(IntPtr handle, List<Rect> regions)
     {
-        lock (_timerLock)
+        lock (_staticLock)
         {
-            _keepBottomTimer?.Stop();
-            _keepBottomTimer?.Dispose();
-            _keepBottomTimer = null;
+            _interactiveRegions[handle] = regions;
+            UpdateWindowScreenOrigin(handle);
+            UpdateWindowDpiScale(handle);
         }
     }
 
-    private static void SetAsDesktopChild(IntPtr handle)
+    private static void ApplyDesktopAttachment(IntPtr handle, bool logSuccess)
     {
-        // 【修复问题4】增强桌面挂载逻辑，支持 Wallpaper Engine 等动态壁纸软件
-        
-        // 方案1: 尝试找到 WorkerW 层（Wallpaper Engine 创建的层）
-        var workerW = IntPtr.Zero;
-        var hDefView = IntPtr.Zero;
-        
-        // 枚举所有顶层窗口
-        var windowHandles = new ArrayList();
-        EnumWindows(EnumWindowsCallback, windowHandles);
-        
-        foreach (IntPtr h in windowHandles)
+        if (handle == IntPtr.Zero || !IsWindow(handle))
         {
-            // 查找 WorkerW 窗口（Wallpaper Engine 创建）
-            var className = GetWindowClassName(h);
-            if (className == "WorkerW")
-            {
-                // 在 WorkerW 下查找 SHELLDLL_DefView
-                var defView = FindWindowEx(h, IntPtr.Zero, "SHELLDLL_DefView", null);
-                if (defView != IntPtr.Zero)
-                {
-                    workerW = h;
-                    hDefView = defView;
-                    break;
-                }
-            }
-        }
-        
-        // 如果找到了 WorkerW 层，使用它作为父窗口
-        if (workerW != IntPtr.Zero && hDefView != IntPtr.Zero)
-        {
-            SetWindowLong(handle, GWL_HWNDPARENT, hDefView.ToInt32());
-            AppLogger.Info("WindowBottomMost", "Mounted to WorkerW layer (Wallpaper Engine detected)");
             return;
         }
 
-        // 方案2: 回退到传统方式，查找 Progman 下的 SHELLDLL_DefView
-        foreach (IntPtr h in windowHandles)
+        SetDesktopChildStyles(handle);
+        InstallMessageHook(handle);
+
+        var attached = TryAttachToDesktopIconHost(handle, out var desktopHost);
+        lock (_staticLock)
         {
-            hDefView = FindWindowEx(h, IntPtr.Zero, "SHELLDLL_DefView", null);
-            if (hDefView != IntPtr.Zero)
+            _desktopWindows[handle] = new DesktopWindowState(desktopHost, attached);
+            if (!_interactiveRegions.ContainsKey(handle))
             {
-                SetWindowLong(handle, GWL_HWNDPARENT, hDefView.ToInt32());
-                AppLogger.Info("WindowBottomMost", "Mounted to traditional desktop layer");
-                break;
+                _interactiveRegions[handle] = [];
             }
+
+            UpdateWindowScreenOrigin(handle);
+            UpdateWindowDpiScale(handle);
+        }
+
+        if (attached)
+        {
+            SetWindowPos(handle, HWND_TOP, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE | SWP_SHOWWINDOW);
+            if (logSuccess)
+            {
+                AppLogger.Info("WindowBottomMost", $"Mounted window to desktop icon host. Window={handle}; Host={desktopHost}");
+            }
+        }
+        else
+        {
+            SetWindowPos(handle, HWND_BOTTOM, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE);
+            if (logSuccess)
+            {
+                AppLogger.Warn("WindowBottomMost", $"Desktop icon host not found. Falling back to HWND_BOTTOM. Window={handle}");
+            }
+        }
+
+        StartDesktopHostMonitorTimer();
+    }
+
+    private static void SetDesktopChildStyles(IntPtr handle)
+    {
+        var style = GetWindowLongPtr(handle, GWL_STYLE).ToInt64();
+        style |= WS_CHILD;
+        style &= ~(WS_POPUP | WS_CAPTION | WS_THICKFRAME | WS_MINIMIZEBOX | WS_MAXIMIZEBOX | WS_SYSMENU);
+        SetWindowLongPtr(handle, GWL_STYLE, new IntPtr(style));
+
+        var exStyle = GetWindowLongPtr(handle, GWL_EXSTYLE).ToInt64();
+        exStyle = (exStyle | WS_EX_TOOLWINDOW | WS_EX_NOACTIVATE | WS_EX_LAYERED) & ~WS_EX_APPWINDOW;
+        SetWindowLongPtr(handle, GWL_EXSTYLE, new IntPtr(exStyle));
+    }
+
+    private static bool TryAttachToDesktopIconHost(IntPtr handle, out IntPtr desktopHost)
+    {
+        desktopHost = ResolveDesktopIconHost();
+        if (desktopHost == IntPtr.Zero || !IsWindow(desktopHost))
+        {
+            return false;
+        }
+
+        if (GetParent(handle) != desktopHost)
+        {
+            _ = SetParent(handle, desktopHost);
+            if (GetParent(handle) != desktopHost)
+            {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    private static IntPtr ResolveDesktopIconHost()
+    {
+        var topLevelWindows = new List<IntPtr>();
+        EnumWindows((handle, _) =>
+        {
+            topLevelWindows.Add(handle);
+            return true;
+        }, IntPtr.Zero);
+
+        foreach (var topLevelWindow in topLevelWindows)
+        {
+            var defView = FindWindowEx(topLevelWindow, IntPtr.Zero, "SHELLDLL_DefView", null);
+            if (defView != IntPtr.Zero)
+            {
+                return defView;
+            }
+        }
+
+        return IntPtr.Zero;
+    }
+
+    private static void StartDesktopHostMonitorTimer()
+    {
+        lock (_timerLock)
+        {
+            if (_desktopHostMonitorTimer != null)
+            {
+                return;
+            }
+
+            _desktopHostMonitorTimer = new System.Timers.Timer(TimeSpan.FromSeconds(2));
+            _desktopHostMonitorTimer.Elapsed += (_, _) => MonitorDesktopHostAttachments();
+            _desktopHostMonitorTimer.Start();
         }
     }
 
-    /// <summary>
-    /// 【修复问题4】获取窗口类名
-    /// </summary>
-    private static string GetWindowClassName(IntPtr hWnd)
+    private static void MonitorDesktopHostAttachments()
     {
-        var buffer = new char[256];
-        var length = GetClassName(hWnd, buffer, buffer.Length);
-        return length > 0 ? new string(buffer, 0, length) : string.Empty;
+        List<IntPtr> handles;
+        lock (_staticLock)
+        {
+            handles = [.. _desktopWindows.Keys];
+        }
+
+        foreach (var handle in handles)
+        {
+            if (!IsWindow(handle))
+            {
+                CleanupWindow(handle);
+                continue;
+            }
+
+            ApplyDesktopAttachment(handle, logSuccess: false);
+        }
     }
 
-    private static bool EnumWindowsCallback(IntPtr handle, ArrayList handles)
+    private static void StopDesktopHostMonitorTimerIfIdle()
     {
-        handles.Add(handle);
-        return true;
+        lock (_timerLock)
+        {
+            lock (_staticLock)
+            {
+                if (_desktopWindows.Count > 0)
+                {
+                    return;
+                }
+            }
+
+            _desktopHostMonitorTimer?.Stop();
+            _desktopHostMonitorTimer?.Dispose();
+            _desktopHostMonitorTimer = null;
+        }
+    }
+
+    private static void CleanupWindow(IntPtr handle)
+    {
+        IntPtr originalWndProc;
+        lock (_staticLock)
+        {
+            if (_originalWndProcs.TryGetValue(handle, out originalWndProc) &&
+                originalWndProc != IntPtr.Zero &&
+                IsWindow(handle))
+            {
+                SetWindowLongPtr(handle, GWLP_WNDPROC, originalWndProc);
+            }
+
+            _desktopWindows.Remove(handle);
+            _originalWndProcs.Remove(handle);
+            _interactiveRegions.Remove(handle);
+            _windowScreenOrigins.Remove(handle);
+            _windowDpiScales.Remove(handle);
+        }
+
+        StopDesktopHostMonitorTimerIfIdle();
     }
 
     private static void InstallMessageHook(IntPtr handle)
     {
+        lock (_staticLock)
+        {
+            if (_originalWndProcs.ContainsKey(handle))
+            {
+                return;
+            }
+        }
+
         var originalWndProc = GetWindowLongPtr(handle, GWLP_WNDPROC);
-        if (originalWndProc == IntPtr.Zero) return;
+        if (originalWndProc == IntPtr.Zero)
+        {
+            return;
+        }
 
         lock (_staticLock)
         {
             _originalWndProcs[handle] = originalWndProc;
-            
-            // 【修复问题1】确保委托实例被静态引用持有，防止 GC 回收
             _wndProcDelegate ??= SubclassWndProc;
         }
 
@@ -325,47 +350,8 @@ internal sealed class WindowsWindowBottomMostService : IWindowBottomMostService
 
     private static IntPtr SubclassWndProc(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam)
     {
-        // 【新增】处理应用激活消息 - 当其他应用激活时立即置底
-        if (msg == WM_ACTIVATEAPP)
-        {
-            lock (_staticLock)
-            {
-                if (_bottomMostWindows.TryGetValue(hWnd, out var isBottomMost) && isBottomMost)
-                {
-                    // 立即置底，不进行频率限制
-                    SendToBottomInternal(hWnd);
-                }
-            }
-        }
-        
-        // 处理 WM_WINDOWPOSCHANGING - 保持置底
-        if (msg == WM_WINDOWPOSCHANGING)
-        {
-            lock (_staticLock)
-            {
-                if (_bottomMostWindows.TryGetValue(hWnd, out var isBottomMost) && isBottomMost)
-                {
-                    // 【修复问题5】优化 Z 轴竞争 - 限制置底操作频率
-                    var now = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();
-                    if (_lastSendToBottomTime.TryGetValue(hWnd, out var lastTime))
-                    {
-                        if (now - lastTime < MinSendToBottomIntervalMs)
-                        {
-                            // 跳过过于频繁的置底操作
-                            goto CallOriginal;
-                        }
-                    }
-                    
-                    SendToBottomInternal(hWnd);
-                    _lastSendToBottomTime[hWnd] = now;
-                }
-            }
-        }
-        
-        // 处理 WM_NCHITTEST - 区域级穿透
         if (msg == WM_NCHITTEST)
         {
-            // WM_NCHITTEST 的鼠标坐标在 lParam（低16位=X，高16位=Y），且为屏幕坐标
             var screenX = (short)(lParam.ToInt64() & 0xFFFF);
             var screenY = (short)((lParam.ToInt64() >> 16) & 0xFFFF);
 
@@ -373,38 +359,27 @@ internal sealed class WindowsWindowBottomMostService : IWindowBottomMostService
             {
                 if (_interactiveRegions.TryGetValue(hWnd, out var regions) && regions.Count > 0)
                 {
-                    // 【修复问题2】获取窗口原点和 DPI 缩放比例
                     _windowScreenOrigins.TryGetValue(hWnd, out var origin);
                     _windowDpiScales.TryGetValue(hWnd, out var dpiScale);
-                    if (dpiScale <= 0) dpiScale = 1.0;  // 默认缩放为 1.0
-                    
-                    // 将屏幕物理像素坐标转为窗口相对坐标
-                    var clientX = screenX - origin.X;
-                    var clientY = screenY - origin.Y;
-                    
-                    // 【修复问题2】将物理像素坐标转换为逻辑 DIP 坐标
-                    // _interactiveRegions 存储的是 Avalonia UI 的逻辑 DIP 坐标
-                    var logicalX = clientX / dpiScale;
-                    var logicalY = clientY / dpiScale;
-                    var point = new Point(logicalX, logicalY);
+                    if (dpiScale <= 0)
+                    {
+                        dpiScale = 1.0;
+                    }
 
+                    var point = new Point((screenX - origin.X) / dpiScale, (screenY - origin.Y) / dpiScale);
                     foreach (var region in regions)
                     {
                         if (region.Contains(point))
                         {
-                            // 在可交互区域内，返回 HTCLIENT
                             return (IntPtr)HTCLIENT;
                         }
                     }
                 }
             }
 
-            // 不在可交互区域内，返回 HTTRANSPARENT 让事件穿透
             return (IntPtr)HTTRANSPARENT;
         }
 
-        // 调用原始窗口过程
-        CallOriginal:
         IntPtr originalWndProc;
         lock (_staticLock)
         {
@@ -417,23 +392,6 @@ internal sealed class WindowsWindowBottomMostService : IWindowBottomMostService
         return CallWindowProc(originalWndProc, hWnd, msg, wParam, lParam);
     }
 
-    /// <summary>
-    /// 设置窗口的可交互区域（供 WindowsRegionPassthroughService 调用）
-    /// </summary>
-    internal static void SetInteractiveRegionsInternal(IntPtr handle, List<Rect> regions)
-    {
-        lock (_staticLock)
-        {
-            _interactiveRegions[handle] = regions;
-            // 同步刷新屏幕原点（DPI 缩放可能影响坐标，每次更新区域时一并刷新）
-            UpdateWindowScreenOrigin(handle);
-            UpdateWindowDpiScale(handle);  // 【修复问题2】同步更新 DPI 缩放
-        }
-    }
-    
-    /// <summary>
-    /// 更新指定窗口的屏幕左上角坐标缓存（用于将 WM_NCHITTEST 屏幕坐标转为窗口相对坐标）
-    /// </summary>
     private static void UpdateWindowScreenOrigin(IntPtr handle)
     {
         if (GetWindowRect(handle, out var rect))
@@ -442,45 +400,55 @@ internal sealed class WindowsWindowBottomMostService : IWindowBottomMostService
         }
     }
 
-    /// <summary>
-    /// 【修复问题2】更新指定窗口的 DPI 缩放比例
-    /// </summary>
     private static void UpdateWindowDpiScale(IntPtr handle)
     {
         try
         {
-            // 获取窗口所在的显示器 DPI
             var monitor = MonitorFromWindow(handle, MONITOR_DEFAULTTONEAREST);
-            if (monitor != IntPtr.Zero)
+            if (monitor != IntPtr.Zero &&
+                GetDpiForMonitor(monitor, MDT_EFFECTIVE_DPI, out var dpiX, out _) == 0)
             {
-                if (GetDpiForMonitor(monitor, MDT_EFFECTIVE_DPI, out var dpiX, out var _) == 0)
-                {
-                    // DPI 缩放比例 = 当前 DPI / 96 (标准 DPI)
-                    _windowDpiScales[handle] = dpiX / 96.0;
-                }
+                _windowDpiScales[handle] = dpiX / 96.0;
+                return;
             }
         }
         catch
         {
-            // 如果获取失败，使用默认缩放 1.0
-            _windowDpiScales[handle] = 1.0;
+            // Use the default below.
+        }
+
+        _windowDpiScales[handle] = 1.0;
+    }
+
+    private static IntPtr GetWindowHandle(Window window)
+    {
+        try
+        {
+            return window.TryGetPlatformHandle()?.Handle ?? IntPtr.Zero;
+        }
+        catch
+        {
+            return IntPtr.Zero;
         }
     }
 
     [StructLayout(LayoutKind.Sequential)]
-    private struct RECT { public int Left, Top, Right, Bottom; }
+    private struct RECT
+    {
+        public int Left;
+        public int Top;
+        public int Right;
+        public int Bottom;
+    }
+
+    private sealed record DesktopWindowState(IntPtr DesktopHost, bool IsDesktopAttached);
+
+    private delegate IntPtr WndProcDelegate(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam);
+    private delegate bool EnumWindowsProc(IntPtr handle, IntPtr lParam);
 
     [DllImport("user32.dll")]
     private static extern bool GetWindowRect(IntPtr hWnd, out RECT lpRect);
 
-    private delegate IntPtr WndProcDelegate(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam);
-    
-    [DllImport("user32.dll", SetLastError = true)]
-    private static extern int GetWindowLong(IntPtr hWnd, int nIndex);
-    
-    [DllImport("user32.dll")]
-    private static extern int SetWindowLong(IntPtr hWnd, int nIndex, int dwNewLong);
-    
     [DllImport("user32.dll", EntryPoint = "GetWindowLongPtr")]
     private static extern IntPtr GetWindowLongPtr(IntPtr hWnd, int nIndex);
 
@@ -490,14 +458,21 @@ internal sealed class WindowsWindowBottomMostService : IWindowBottomMostService
     [DllImport("user32.dll")]
     private static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int x, int y, int cx, int cy, uint flags);
 
+    [DllImport("user32.dll", SetLastError = true)]
+    private static extern IntPtr SetParent(IntPtr hWndChild, IntPtr hWndNewParent);
+
+    [DllImport("user32.dll")]
+    private static extern IntPtr GetParent(IntPtr hWnd);
+
+    [DllImport("user32.dll")]
+    private static extern bool IsWindow(IntPtr hWnd);
+
     [DllImport("user32.dll", SetLastError = true)]
     private static extern IntPtr FindWindowEx(IntPtr hParent, IntPtr hChildAfter, string? lpszClass, string? lpszWindow);
 
-    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
+    [DllImport("user32.dll", SetLastError = true)]
     [return: MarshalAs(UnmanagedType.Bool)]
-    private static extern bool EnumWindows(EnumWindowsProc lpEnumFunc, ArrayList lParam);
-    
-    private delegate bool EnumWindowsProc(IntPtr handle, ArrayList handles);
+    private static extern bool EnumWindows(EnumWindowsProc lpEnumFunc, IntPtr lParam);
 
     [DllImport("user32.dll")]
     private static extern IntPtr CallWindowProc(IntPtr lpPrevWndFunc, IntPtr hWnd, int Msg, IntPtr wParam, IntPtr lParam);
@@ -505,24 +480,13 @@ internal sealed class WindowsWindowBottomMostService : IWindowBottomMostService
     [DllImport("user32.dll")]
     private static extern IntPtr DefWindowProc(IntPtr hWnd, int uMsg, IntPtr wParam, IntPtr lParam);
 
-    // 【修复问题2】DPI 相关的 P/Invoke 声明
-    private const int MONITOR_DEFAULTTONEAREST = 2;
-    private const int MDT_EFFECTIVE_DPI = 0;
-    
     [DllImport("user32.dll")]
     private static extern IntPtr MonitorFromWindow(IntPtr hWnd, int dwFlags);
 
     [DllImport("shcore.dll")]
     private static extern int GetDpiForMonitor(IntPtr hmonitor, int dpiType, out uint dpiX, out uint dpiY);
-    
-    // 【修复问题4】获取窗口类名的 P/Invoke
-    [DllImport("user32.dll", CharSet = CharSet.Auto)]
-    private static extern int GetClassName(IntPtr hWnd, char[] lpClassName, int nMaxCount);
 }
 
-/// <summary>
-/// Windows 平台区域级穿透服务 - 使用 WM_NCHITTEST
-/// </summary>
 internal sealed class WindowsRegionPassthroughService : IRegionPassthroughService
 {
     public bool IsRegionPassthroughSupported => true;
@@ -546,14 +510,17 @@ internal sealed class WindowsRegionPassthroughService : IRegionPassthroughServic
 
     private static IntPtr GetWindowHandle(Window window)
     {
-        try { return window.TryGetPlatformHandle()?.Handle ?? IntPtr.Zero; }
-        catch { return IntPtr.Zero; }
+        try
+        {
+            return window.TryGetPlatformHandle()?.Handle ?? IntPtr.Zero;
+        }
+        catch
+        {
+            return IntPtr.Zero;
+        }
     }
 }
 
-/// <summary>
-/// 空实现
-/// </summary>
 internal sealed class NullWindowBottomMostService : IWindowBottomMostService
 {
     public bool IsBottomMostSupported => false;

LanMountainDesktop/ViewModels/UpdateSettingsViewModel.cs

@@ -48,24 +48,43 @@ public sealed partial class UpdateSettingsViewModel : ViewModelBase, IDisposable
     [ObservableProperty] private double _downloadThreadsSliderValue = UpdateSettingsValues.DefaultDownloadThreads;
 
     public bool IsBusy => CurrentPhase.IsBusy();
+    public bool IsPaused => CurrentPhase.IsPaused();
     public bool CanCheck => CurrentPhase.CanCheck();
     public bool CanDownload => CurrentPhase.CanDownload();
     public bool CanInstall => CurrentPhase.CanInstall();
     public bool CanRollback => CurrentPhase.CanRollback();
-    public bool IsProgressVisible => CurrentPhase is UpdatePhase.Checking or UpdatePhase.Downloading or UpdatePhase.Installing or UpdatePhase.Verifying or UpdatePhase.RollingBack;
+    public bool CanPause => CurrentPhase.CanPause();
+    public bool CanResume => CurrentPhase.CanResume();
+    public bool CanCancel => CurrentPhase.CanCancel();
+    public bool IsProgressVisible => CurrentPhase is UpdatePhase.Checking or UpdatePhase.Downloading or UpdatePhase.PausedDownloading or UpdatePhase.Installing or UpdatePhase.Verifying or UpdatePhase.RollingBack;
+    public string PhaseText => CurrentPhase switch
+    {
+        UpdatePhase.PausedDownloading => "Paused (Download)",
+        UpdatePhase.PausedInstalling => "Paused (Install)",
+        UpdatePhase.Recovering => "Recovering Install",
+        _ => CurrentPhase.ToString()
+    };
 
     partial void OnCurrentPhaseChanged(UpdatePhase value)
     {
         OnPropertyChanged(nameof(IsBusy));
+        OnPropertyChanged(nameof(IsPaused));
         OnPropertyChanged(nameof(CanCheck));
         OnPropertyChanged(nameof(CanDownload));
         OnPropertyChanged(nameof(CanInstall));
         OnPropertyChanged(nameof(CanRollback));
+        OnPropertyChanged(nameof(CanPause));
+        OnPropertyChanged(nameof(CanResume));
+        OnPropertyChanged(nameof(CanCancel));
         OnPropertyChanged(nameof(IsProgressVisible));
+        OnPropertyChanged(nameof(PhaseText));
         CheckCommand.NotifyCanExecuteChanged();
         DownloadCommand.NotifyCanExecuteChanged();
         InstallCommand.NotifyCanExecuteChanged();
         RollbackCommand.NotifyCanExecuteChanged();
+        PauseCommand.NotifyCanExecuteChanged();
+        ResumeCommand.NotifyCanExecuteChanged();
+        CancelCommand.NotifyCanExecuteChanged();
     }
 
     partial void OnSelectedUpdateChannelValueChanged(string value)
@@ -121,6 +140,10 @@ public sealed partial class UpdateSettingsViewModel : ViewModelBase, IDisposable
         {
             StatusMessage = "Download complete. Ready to install.";
         }
+        else if (result.ErrorMessage is not null && result.ErrorMessage.Contains("stale or invalid", StringComparison.OrdinalIgnoreCase))
+        {
+            StatusMessage = "Install resume state is invalid. Cancel and redownload, then retry.";
+        }
         else
         {
             StatusMessage = result.ErrorMessage ?? "Download failed.";
@@ -138,7 +161,7 @@ public sealed partial class UpdateSettingsViewModel : ViewModelBase, IDisposable
         }
         else
         {
-            StatusMessage = result.ErrorMessage ?? "Install failed.";
+            StatusMessage = result.ErrorMessage ?? result.ErrorCode ?? "Install failed.";
         }
     }
 
@@ -150,6 +173,37 @@ public sealed partial class UpdateSettingsViewModel : ViewModelBase, IDisposable
         StatusMessage = "Rollback complete.";
     }
 
+    [RelayCommand(CanExecute = nameof(CanPause))]
+    private async Task PauseAsync()
+    {
+        await _orchestrator.PauseAsync();
+        StatusMessage = "Update paused.";
+    }
+
+    [RelayCommand(CanExecute = nameof(CanResume))]
+    private async Task ResumeAsync()
+    {
+        StatusMessage = "Resuming update...";
+        var result = await _orchestrator.ResumeAsync(CancellationToken.None);
+        if (result.Success)
+        {
+            StatusMessage = "Download complete. Ready to install.";
+        }
+        else
+        {
+            StatusMessage = result.ErrorMessage ?? "Resume failed.";
+        }
+    }
+
+    [RelayCommand(CanExecute = nameof(CanCancel))]
+    private async Task CancelAsync()
+    {
+        await _orchestrator.CancelAsync();
+        StatusMessage = "Update canceled.";
+        ProgressDetail = string.Empty;
+        ProgressFraction = 0;
+    }
+
     private void OnOrchestratorPhaseChanged(UpdatePhase phase)
     {
         CurrentPhase = phase;

LanMountainDesktop/Views/DesktopWidgetWindow.axaml.cs

@@ -2,14 +2,11 @@ using System;
 using System.Collections.Generic;
 using Avalonia;
 using Avalonia.Controls;
-using LanMountainDesktop.Services;
 using Avalonia.Threading;
+using LanMountainDesktop.Services;
 
 namespace LanMountainDesktop.Views;
 
-/// <summary>
-/// 表示一个独立的组件挂载窗口。它不含有任何自己的边窗，仅仅负责包裹组件并将自身植入系统最底层。
-/// </summary>
 public partial class DesktopWidgetWindow : Window
 {
     private readonly IWindowBottomMostService _bottomMostService = WindowBottomMostServiceFactory.GetOrCreate();
@@ -18,6 +15,11 @@ public partial class DesktopWidgetWindow : Window
     public DesktopWidgetWindow()
     {
         InitializeComponent();
+
+        if (OperatingSystem.IsWindows())
+        {
+            _bottomMostService.SetupBottomMost(this);
+        }
     }
 
     public DesktopWidgetWindow(Control componentContent) : this()
@@ -48,11 +50,7 @@ public partial class DesktopWidgetWindow : Window
 
         if (OperatingSystem.IsWindows())
         {
-            // 通过现有的置底服务将独立的小窗口锁定到底层
-            _bottomMostService.SetupBottomMost(this);
             _bottomMostService.SendToBottom(this);
-
-            // 当窗口展示完毕且有了尺寸后，更新可交互区域，使得整个组件都能被点击
             Dispatcher.UIThread.Post(UpdateInteractiveRegion, DispatcherPriority.Render);
         }
     }
@@ -69,7 +67,6 @@ public partial class DesktopWidgetWindow : Window
 
     private void UpdateInteractiveRegion()
     {
-        // 既然是一个完全紧贴在组件身上的小窗，它的全部都是可交互的
         _regionPassthroughService.SetInteractiveRegions(this, new List<Rect>
         {
             new(0, 0, Bounds.Width, Bounds.Height)

LanMountainDesktop/Views/FusedDesktopComponentLibraryControl.axaml

@@ -8,16 +8,23 @@
     <UserControl.Styles>
         <Style Selector="ListBoxItem.category-item">
             <Setter Property="Padding" Value="0"/>
-            <Setter Property="Margin" Value="0,2"/>
+            <Setter Property="Margin" Value="0,3"/>
             <Setter Property="Background" Value="Transparent"/>
             <Setter Property="CornerRadius" Value="{DynamicResource DesignCornerRadiusSm}"/>
+            <Setter Property="MinHeight" Value="44"/>
         </Style>
         <Style Selector="ListBoxItem.category-item:pointerover /template/ ContentPresenter#PART_ContentPresenter">
-            <Setter Property="Background" Value="{DynamicResource SubtleFillColorSecondaryBrush}"/>
+            <Setter Property="Background" Value="{DynamicResource AdaptiveButtonHoverBackgroundBrush}"/>
         </Style>
         <Style Selector="ListBoxItem.category-item:selected /template/ ContentPresenter#PART_ContentPresenter">
             <Setter Property="Background" Value="{DynamicResource AdaptiveNavItemSelectedBackgroundBrush}"/>
         </Style>
+        <Style Selector="ListBoxItem.category-item Border.category-selection-indicator">
+            <Setter Property="Opacity" Value="0"/>
+        </Style>
+        <Style Selector="ListBoxItem.category-item:selected Border.category-selection-indicator">
+            <Setter Property="Opacity" Value="1"/>
+        </Style>
         <Style Selector="ListBoxItem.category-item TextBlock.category-text">
             <Setter Property="Foreground" Value="{DynamicResource AdaptiveTextPrimaryBrush}"/>
         </Style>
@@ -25,27 +32,65 @@
             <Setter Property="Foreground" Value="{DynamicResource AdaptiveTextPrimaryBrush}"/>
             <Setter Property="FontWeight" Value="SemiBold"/>
         </Style>
+        <Style Selector="Button.fused-library-link">
+            <Setter Property="Background" Value="Transparent"/>
+            <Setter Property="BorderThickness" Value="0"/>
+            <Setter Property="Padding" Value="6,4"/>
+            <Setter Property="MinHeight" Value="28"/>
+            <Setter Property="Foreground" Value="{DynamicResource AdaptiveTextSecondaryBrush}"/>
+        </Style>
+        <Style Selector="Button.fused-library-link:pointerover">
+            <Setter Property="Background" Value="{DynamicResource AdaptiveButtonHoverBackgroundBrush}"/>
+        </Style>
+        <Style Selector="Button.fused-library-add-button">
+            <Setter Property="Background" Value="{DynamicResource AdaptiveAccentBrush}"/>
+            <Setter Property="BorderBrush" Value="{DynamicResource AdaptiveAccentBrush}"/>
+            <Setter Property="Foreground" Value="{DynamicResource AdaptiveOnAccentBrush}"/>
+            <Setter Property="CornerRadius" Value="{DynamicResource DesignCornerRadiusSm}"/>
+            <Setter Property="MinHeight" Value="38"/>
+            <Setter Property="Padding" Value="22,8"/>
+        </Style>
+        <Style Selector="Button.fused-library-add-button:pointerover">
+            <Setter Property="Background" Value="{DynamicResource AdaptiveAccentLightBrush}"/>
+        </Style>
+        <Style Selector="Button.fused-library-add-button TextBlock">
+            <Setter Property="Foreground" Value="{DynamicResource AdaptiveOnAccentBrush}"/>
+        </Style>
+        <Style Selector="Button.fused-library-add-button fi|FluentIcon">
+            <Setter Property="Foreground" Value="{DynamicResource AdaptiveOnAccentBrush}"/>
+        </Style>
     </UserControl.Styles>
 
-    <Grid ColumnDefinitions="Auto,*">
-        <Border Width="280" Background="Transparent">
+    <Grid ColumnDefinitions="190,*">
+        <Border Background="Transparent">
             <Grid RowDefinitions="*,Auto">
                 <ListBox x:Name="CategoryListBox"
                          Grid.Row="0"
                          Background="Transparent"
                          BorderThickness="0"
-                         Margin="8,8,4,0"
+                         Margin="0,0,14,0"
                          SelectionChanged="OnCategorySelectionChanged"
                          ItemsSource="{Binding Categories}">
                     <ListBox.ItemTemplate>
                         <DataTemplate x:DataType="vm:ComponentLibraryCategoryViewModel">
-                            <Grid ColumnDefinitions="Auto,*" ColumnSpacing="12" Margin="12,10">
+                            <Grid ColumnDefinitions="Auto,Auto,*"
+                                  ColumnSpacing="10"
+                                  Margin="0,2,8,2">
+                                <Border Classes="category-selection-indicator"
+                                        Width="3"
+                                        Height="22"
+                                        CornerRadius="{DynamicResource DesignCornerRadiusMicro}"
+                                        Background="{DynamicResource AdaptiveAccentBrush}"
+                                        VerticalAlignment="Center"/>
                                 <fi:FluentIcon Icon="{Binding Icon}"
+                                               Grid.Column="1"
                                                IconVariant="Regular"
-                                               FontSize="18"/>
-                                <TextBlock Grid.Column="1"
+                                               FontSize="16"
+                                               VerticalAlignment="Center"/>
+                                <TextBlock Grid.Column="2"
                                            VerticalAlignment="Center"
                                            FontSize="14"
+                                           TextTrimming="CharacterEllipsis"
                                            Classes="category-text"
                                            Text="{Binding Title}"/>
                             </Grid>
@@ -53,17 +98,17 @@
                     </ListBox.ItemTemplate>
                 </ListBox>
 
-                <StackPanel Grid.Row="1" Margin="12,8,8,12">
+                <StackPanel Grid.Row="1" Margin="0,8,14,4">
                     <Border Height="1"
                             Background="{DynamicResource AdaptiveGlassPanelBorderBrush}"
                             Opacity="0.4"
                             Margin="0,0,0,8"/>
-                    <Button Classes="hyperlink"
+                    <Button Classes="fused-library-link"
                             HorizontalAlignment="Left"
                             Click="OnFindMoreComponentsClick">
                         <StackPanel Orientation="Horizontal" Spacing="6">
                             <fi:FluentIcon Icon="Globe" IconVariant="Regular" FontSize="14"/>
-                            <TextBlock Text="Find More Components"/>
+                            <TextBlock Text="查找更多组件" FontSize="12"/>
                         </StackPanel>
                     </Button>
                 </StackPanel>
@@ -74,55 +119,73 @@
                 Width="1"
                 HorizontalAlignment="Left"
                 Background="{DynamicResource AdaptiveGlassPanelBorderBrush}"
-                Opacity="0.5"/>
+                Opacity="0.35"/>
 
         <ScrollViewer Grid.Column="1"
                       VerticalScrollBarVisibility="Auto"
                       HorizontalScrollBarVisibility="Disabled">
-            <StackPanel Margin="16,8,12,8">
+            <StackPanel Margin="28,8,8,10">
                 <Panel IsVisible="{Binding SelectedComponent, Converter={x:Static converters:ObjectConverters.IsNotNull}}">
-                    <Border Classes="surface-translucent-panel"
-                            CornerRadius="{DynamicResource DesignCornerRadiusLg}"
-                            Padding="20">
-                        <StackPanel Spacing="16">
-                            <TextBlock FontSize="28"
-                                       FontWeight="SemiBold"
-                                       Foreground="{DynamicResource AdaptiveTextPrimaryBrush}"
-                                       Text="{Binding SelectedComponent.DisplayName}"/>
+                    <Grid RowDefinitions="Auto,Auto,*,Auto"
+                          MinHeight="330">
+                        <TextBlock FontSize="24"
+                                   FontWeight="SemiBold"
+                                   Foreground="{DynamicResource AdaptiveTextPrimaryBrush}"
+                                   Text="{Binding SelectedComponent.DisplayName}"
+                                   TextTrimming="CharacterEllipsis"/>
 
+                        <TextBlock Grid.Row="1"
+                                   Margin="0,6,0,14"
+                                   MaxHeight="44"
+                                   FontSize="13"
+                                   Foreground="{DynamicResource AdaptiveTextSecondaryBrush}"
+                                   Opacity="0.82"
+                                   Text="{Binding SelectedComponent.Description}"
+                                   TextWrapping="Wrap"
+                                   TextTrimming="CharacterEllipsis"/>
+
+                        <Border Grid.Row="2"
+                                CornerRadius="{DynamicResource DesignCornerRadiusLg}"
+                                Background="{DynamicResource AdaptiveSurfaceOverlayBrush}"
+                                BorderBrush="{DynamicResource AdaptiveGlassPanelBorderBrush}"
+                                BorderThickness="1"
+                                Width="390"
+                                Height="230"
+                                HorizontalAlignment="Center"
+                                VerticalAlignment="Center">
                             <Border CornerRadius="{DynamicResource DesignCornerRadiusSm}"
-                                    Background="{DynamicResource AdaptiveSurfaceBaseBrush}"
+                                    Background="{DynamicResource AdaptiveGlassPanelBackgroundBrush}"
                                     BorderBrush="{DynamicResource AdaptiveGlassPanelBorderBrush}"
                                     BorderThickness="1"
-                                    Width="420"
-                                    Height="300"
-                                    HorizontalAlignment="Center">
+                                    Padding="12"
+                                    HorizontalAlignment="Center"
+                                    VerticalAlignment="Center">
                                 <ContentControl x:Name="SelectedComponentPreviewHost"
-                                                Margin="16"
                                                 HorizontalAlignment="Center"
                                                 VerticalAlignment="Center"
                                                 IsHitTestVisible="False"
                                                 Focusable="False"/>
                             </Border>
+                        </Border>
 
-                            <Button HorizontalAlignment="Center"
-                                    Classes="accent"
-                                    Padding="24,10"
-                                    Tag="{Binding SelectedComponent.ComponentId}"
-                                    Click="OnAddComponentClick">
-                                <StackPanel Orientation="Horizontal" Spacing="8">
-                                    <fi:FluentIcon Icon="Add" IconVariant="Regular" FontSize="16"/>
-                                    <TextBlock Text="Add Component" FontWeight="SemiBold"/>
-                                </StackPanel>
-                            </Button>
-                        </StackPanel>
-                    </Border>
+                        <Button Grid.Row="3"
+                                HorizontalAlignment="Center"
+                                Margin="0,18,0,0"
+                                Classes="fused-library-add-button"
+                                Tag="{Binding SelectedComponent.ComponentId}"
+                                Click="OnAddComponentClick">
+                            <StackPanel Orientation="Horizontal" Spacing="8">
+                                <fi:FluentIcon Icon="Add" IconVariant="Regular" FontSize="16"/>
+                                <TextBlock Text="添加" FontWeight="SemiBold"/>
+                            </StackPanel>
+                        </Button>
+                    </Grid>
                 </Panel>
 
                 <Grid IsVisible="{Binding SelectedComponent, Converter={x:Static converters:ObjectConverters.IsNull}}"
                       HorizontalAlignment="Center"
                       VerticalAlignment="Center"
-                      MinHeight="400">
+                      MinHeight="330">
                     <StackPanel Spacing="16"
                                 HorizontalAlignment="Center"
                                 VerticalAlignment="Center">
@@ -134,7 +197,7 @@
                         <TextBlock HorizontalAlignment="Center"
                                    FontSize="16"
                                    Foreground="{DynamicResource AdaptiveTextSecondaryBrush}"
-                                   Text="Select a component to view its details."/>
+                                   Text="选择一个分类以查看可添加组件。"/>
                     </StackPanel>
                 </Grid>
             </StackPanel>

LanMountainDesktop/Views/FusedDesktopComponentLibraryControl.axaml.cs

@@ -94,7 +94,7 @@ public partial class FusedDesktopComponentLibraryControl : UserControl
             var categoryComponents = _allDefinitions
                 .Where(definition => string.Equals(definition.Category, category, StringComparison.OrdinalIgnoreCase))
                 .OrderBy(static definition => definition.DisplayName, StringComparer.OrdinalIgnoreCase)
-                .Select(CreateComponentItem)
+                .Select(definition => CreateComponentItem(definition, languageCode))
                 .ToArray();
 
             _viewModel.Categories.Add(new ComponentLibraryCategoryViewModel(
@@ -112,7 +112,7 @@ public partial class FusedDesktopComponentLibraryControl : UserControl
         if (string.Equals(categoryId, "Weather", StringComparison.OrdinalIgnoreCase)) return Symbol.WeatherSunny;
         if (string.Equals(categoryId, "Board", StringComparison.OrdinalIgnoreCase)) return Symbol.Edit;
         if (string.Equals(categoryId, "Media", StringComparison.OrdinalIgnoreCase)) return Symbol.Play;
-        if (string.Equals(categoryId, "Info", StringComparison.OrdinalIgnoreCase)) return Symbol.Apps;
+        if (string.Equals(categoryId, "Info", StringComparison.OrdinalIgnoreCase)) return Symbol.Info;
         if (string.Equals(categoryId, "Calculator", StringComparison.OrdinalIgnoreCase)) return Symbol.Calculator;
         if (string.Equals(categoryId, "Study", StringComparison.OrdinalIgnoreCase)) return Symbol.Hourglass;
         if (string.Equals(categoryId, "File", StringComparison.OrdinalIgnoreCase)) return Symbol.Folder;
@@ -138,9 +138,11 @@ public partial class FusedDesktopComponentLibraryControl : UserControl
         return LocalizationService.GetString(languageCode, key, fallback);
     }
 
-    private static ComponentLibraryItemViewModel CreateComponentItem(DesktopComponentDefinition definition)
+    private ComponentLibraryItemViewModel CreateComponentItem(DesktopComponentDefinition definition, string languageCode)
     {
-        return new ComponentLibraryItemViewModel(definition.Id, definition.DisplayName);
+        var categoryTitle = GetLocalizedCategoryTitle(languageCode, definition.Category);
+        var description = $"{categoryTitle} - {Math.Max(1, definition.MinWidthCells)} x {Math.Max(1, definition.MinHeightCells)}";
+        return new ComponentLibraryItemViewModel(definition.Id, definition.DisplayName, description);
     }
 
     private void OnCategorySelectionChanged(object? sender, SelectionChangedEventArgs e)
@@ -174,7 +176,7 @@ public partial class FusedDesktopComponentLibraryControl : UserControl
         }
 
         _viewModel.SelectedComponent = selectedCategory.Components.FirstOrDefault(component => component.ComponentId == firstComponent.Id)
-            ?? CreateComponentItem(firstComponent);
+            ?? CreateComponentItem(firstComponent, _settingsFacade.Region.Get().LanguageCode);
         SetSelectedPreviewControl(CreateStaticPreviewControl(firstComponent));
     }
 

LanMountainDesktop/Views/FusedDesktopComponentLibraryWindow.axaml

@@ -1,72 +1,62 @@
 <Window xmlns="https://github.com/avaloniaui"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:controls="using:LanMountainDesktop.Views"
-        xmlns:fi="using:FluentIcons.Avalonia"
         x:Class="LanMountainDesktop.Views.FusedDesktopComponentLibraryWindow"
-        Width="860"
-        Height="620"
+        Width="740"
+        Height="500"
         MinWidth="600"
-        MinHeight="500"
+        MinHeight="440"
         CanResize="True"
         WindowStartupLocation="CenterScreen"
-        WindowDecorations="BorderOnly"
+        WindowDecorations="None"
         ExtendClientAreaToDecorationsHint="True"
-        ExtendClientAreaTitleBarHeightHint="48"
         Background="Transparent"
         Title="Add Component">
 
     <Grid x:Name="RootGrid"
           Classes="settings-scope"
-          Background="{DynamicResource AdaptiveSettingsWindowBackgroundBrush}"
-          RowDefinitions="Auto,*">
-        <Border x:Name="WindowTitleBarHost"
-                Height="48"
-                Padding="12,0,12,0"
-                Background="{DynamicResource AdaptiveSettingsWindowBackgroundBrush}"
-                BorderBrush="{DynamicResource AdaptiveSettingsWindowBorderBrush}"
-                BorderThickness="0,0,0,1"
-                PointerPressed="OnWindowTitleBarPointerPressed">
-            <Grid ColumnDefinitions="Auto,Auto,*,Auto"
-                  ColumnSpacing="8"
-                  VerticalAlignment="Center">
-                <fi:FluentIcon x:Name="WindowBrandIcon"
-                               Icon="Apps"
-                               IconVariant="Filled"
-                               FontSize="16"
-                               IsHitTestVisible="False"
-                               VerticalAlignment="Center" />
-
-                <TextBlock x:Name="WindowTitleTextBlock"
-                           Grid.Column="1"
-                           FontSize="12"
-                           FontWeight="SemiBold"
-                           IsHitTestVisible="False"
-                           Text="Add Component" />
-
-                <TextBlock Grid.Column="2"
-                           FontSize="12"
-                           Opacity="0.6"
-                           IsHitTestVisible="False"
-                           VerticalAlignment="Center"
-                           Text="Browse available widgets and add them to the current fused desktop layout." />
-
-                <Button x:Name="CloseWindowButton"
-                        Grid.Column="3"
-                        Width="40"
-                        Height="32"
-                        Padding="0"
+          Background="Transparent">
+        <Border x:Name="PanelShell"
+                Classes="surface-translucent-strong"
+                Width="720"
+                MaxWidth="720"
+                HorizontalAlignment="Center"
+                VerticalAlignment="Center"
+                Padding="0"
+                ClipToBounds="True">
+            <Grid RowDefinitions="Auto,*,Auto">
+                <Border Height="64"
+                        Padding="24,0,24,0"
                         Background="Transparent"
-                        BorderThickness="0"
-                        Click="OnCloseClick">
-                    <fi:FluentIcon Icon="Dismiss"
-                                   IconVariant="Regular"
-                                   FontSize="16" />
-                </Button>
+                        PointerPressed="OnWindowTitleBarPointerPressed">
+                    <TextBlock VerticalAlignment="Center"
+                               FontSize="22"
+                               FontWeight="SemiBold"
+                               Foreground="{DynamicResource AdaptiveTextPrimaryBrush}"
+                               Text="添加小组件" />
+                </Border>
+
+                <controls:FusedDesktopComponentLibraryControl x:Name="LibraryControl"
+                                                              Grid.Row="1"
+                                                              Margin="22,0,22,8" />
+
+                <Border Grid.Row="2"
+                        Padding="24,16,24,22"
+                        BorderBrush="{DynamicResource AdaptiveGlassPanelBorderBrush}"
+                        BorderThickness="0,1,0,0">
+                    <Button x:Name="CloseWindowButton"
+                            HorizontalAlignment="Stretch"
+                            MinHeight="32"
+                            Padding="16,7"
+                            Background="{DynamicResource AdaptiveButtonBackgroundBrush}"
+                            BorderThickness="0"
+                            Click="OnCloseClick">
+                        <TextBlock HorizontalAlignment="Center"
+                                   FontSize="14"
+                                   Text="关闭" />
+                    </Button>
+                </Border>
             </Grid>
         </Border>
-
-        <controls:FusedDesktopComponentLibraryControl x:Name="LibraryControl"
-                                                      Grid.Row="1"
-                                                      Margin="12,8,16,8" />
     </Grid>
 </Window>

LanMountainDesktop/Views/FusedDesktopComponentLibraryWindow.axaml.cs

@@ -1,50 +1,55 @@
 using System;
 using Avalonia;
 using Avalonia.Controls;
+using Avalonia.Controls.ApplicationLifetimes;
 using Avalonia.Input;
 using Avalonia.Interactivity;
-using LanMountainDesktop.ComponentSystem;
 using LanMountainDesktop.Services;
-using LanMountainDesktop.Services.Settings;
-using Avalonia.Controls.ApplicationLifetimes;
 
 namespace LanMountainDesktop.Views;
 
-/// <summary>
-/// 融合桌面组件库窗口 - 专门用于添加组件到系统桌面（负一屏）
-/// 
-/// 注意：此窗口只能添加组件到融合桌面，不能添加到阑山桌面
-/// </summary>
 public partial class FusedDesktopComponentLibraryWindow : Window
 {
-    private readonly IFusedDesktopLayoutService _layoutService = FusedDesktopLayoutServiceProvider.GetOrCreate();
-    private readonly ISettingsFacadeService _settingsFacade = HostSettingsFacadeProvider.GetOrCreate();
     private TransparentOverlayWindow? _overlayWindow;
 
-    // 与 TransparentOverlayWindow 保持一致的默认 cellSize
-    private const double DefaultCellSize = 100;
-    
     public FusedDesktopComponentLibraryWindow()
     {
         InitializeComponent();
 
         LibraryControl.AddComponentRequested += OnAddComponentRequested;
+        KeyDown += OnWindowKeyDown;
 
         var mainWindow = (Application.Current?.ApplicationLifetime as IClassicDesktopStyleApplicationLifetime)?.MainWindow as MainWindow;
         mainWindow?.RegisterFusedLibraryWindow(this);
     }
 
-    /// <summary>
-    /// 设置透明覆盖层窗口引用
-    /// </summary>
+    public bool PreserveEditModeOnClose { get; private set; }
+
     public void SetOverlayWindow(TransparentOverlayWindow overlayWindow)
     {
         _overlayWindow = overlayWindow;
     }
 
-    /// <summary>
-    /// 添加组件请求处理 - 将组件放置在屏幕（覆盖层画布）中央
-    /// </summary>
+    public void CenterInWorkArea(Window? referenceWindow = null)
+    {
+        var screen = referenceWindow is not null
+            ? Screens.ScreenFromWindow(referenceWindow)
+            : Screens.Primary;
+        screen ??= Screens.Primary;
+        if (screen is null)
+        {
+            return;
+        }
+
+        var scaling = screen.Scaling;
+        var workArea = screen.WorkingArea;
+        var widthPx = (int)Math.Round(Math.Max(MinWidth, Width) * scaling);
+        var heightPx = (int)Math.Round(Math.Max(MinHeight, Height) * scaling);
+        var x = workArea.X + Math.Max(0, (workArea.Width - widthPx) / 2);
+        var y = workArea.Y + Math.Max(0, (workArea.Height - heightPx) / 2);
+        Position = new PixelPoint(x, y);
+    }
+
     private void OnAddComponentRequested(object? sender, string componentId)
     {
         if (_overlayWindow is null)
@@ -53,54 +58,16 @@ public partial class FusedDesktopComponentLibraryWindow : Window
             return;
         }
 
-        // 计算组件的像素尺寸
-        var (componentWidth, componentHeight) = ResolveComponentSize(componentId);
+        _overlayWindow.AddComponentToCenter(componentId);
+        AppLogger.Info("FusedDesktopLibrary", $"Added component '{componentId}' at fused desktop grid center.");
 
-        // 取覆盖层画布的中心点，减去组件半尺寸，使组件出现在屏幕正中央
-        var overlayBounds = _overlayWindow.Bounds;
-        var centerX = overlayBounds.Width / 2.0 - componentWidth / 2.0;
-        var centerY = overlayBounds.Height / 2.0 - componentHeight / 2.0;
-        
-        // 边界保护：确保组件不超出屏幕边界
-        centerX = Math.Max(0, Math.Min(centerX, overlayBounds.Width - componentWidth));
-        centerY = Math.Max(0, Math.Min(centerY, overlayBounds.Height - componentHeight));
-        
-        _overlayWindow.AddComponent(componentId, centerX, centerY, componentWidth, componentHeight);
-        
-        AppLogger.Info("FusedDesktopLibrary",
-            $"Added component '{componentId}' at center ({centerX:F0}, {centerY:F0}) size ({componentWidth}x{componentHeight}).");
-        
-        // 关闭窗口
+        PreserveEditModeOnClose = true;
         Close();
     }
 
-    /// <summary>
-    /// 解析组件的默认像素尺寸（基于组件定义的 MinCells * DefaultCellSize）
-    /// </summary>
-    private (double Width, double Height) ResolveComponentSize(string componentId)
-    {
-        try
-        {
-            var pluginRuntimeService = (Application.Current as App)?.PluginRuntimeService;
-            var registry = DesktopComponentRegistryFactory.Create(pluginRuntimeService);
-            if (registry.TryGetDefinition(componentId, out var definition))
-            {
-                var w = Math.Max(1, definition.MinWidthCells) * DefaultCellSize;
-                var h = Math.Max(1, definition.MinHeightCells) * DefaultCellSize;
-                return (w, h);
-            }
-        }
-        catch (Exception ex)
-        {
-            AppLogger.Warn("FusedDesktopLibrary", $"Failed to resolve component size for '{componentId}'.", ex);
-        }
-        
-        // 回退为 2×2 格子的默认尺寸
-        return (DefaultCellSize * 2, DefaultCellSize * 2);
-    }
-    
     private void OnCloseClick(object? sender, RoutedEventArgs e)
     {
+        PreserveEditModeOnClose = false;
         Close();
     }
 
@@ -112,9 +79,21 @@ public partial class FusedDesktopComponentLibraryWindow : Window
         }
     }
 
+    private void OnWindowKeyDown(object? sender, KeyEventArgs e)
+    {
+        if (e.Key == Key.Escape)
+        {
+            PreserveEditModeOnClose = false;
+            Close();
+        }
+    }
+
     protected override void OnClosed(EventArgs e)
     {
+        LibraryControl.AddComponentRequested -= OnAddComponentRequested;
+        KeyDown -= OnWindowKeyDown;
         base.OnClosed(e);
+
         var mainWindow = (Application.Current?.ApplicationLifetime as IClassicDesktopStyleApplicationLifetime)?.MainWindow as MainWindow;
         mainWindow?.UnregisterFusedLibraryWindow(this);
     }

LanMountainDesktop/Views/MainWindow.SettingsHardCut.Stubs.cs

@@ -15,6 +15,7 @@ using FluentAvalonia.UI.Controls;
 using LanMountainDesktop.Models;
 using LanMountainDesktop.PluginSdk;
 using LanMountainDesktop.Services;
+using LanMountainDesktop.Services.Update;
 using LanMountainDesktop.Theme;
 using LanMountainDesktop.Views.Components;
 
@@ -475,28 +476,14 @@ public partial class MainWindow : Window
 
     private void TriggerAutoUpdateCheckIfEnabled()
     {
-        var versionText = _settingsFacade.ApplicationInfo.GetAppVersionText();
-        if (!Version.TryParse(versionText, out var currentVersion))
-        {
-            currentVersion = new Version(0, 0, 0);
-        }
-
-        var major = Math.Max(0, currentVersion.Major);
-        var minor = Math.Max(0, currentVersion.Minor);
-        var build = Math.Max(0, currentVersion.Build >= 0 ? currentVersion.Build : 0);
-        var revision = Math.Max(0, currentVersion.Revision >= 0 ? currentVersion.Revision : 0);
-        var normalizedVersion = revision > 0
-            ? new Version(major, minor, build, revision)
-            : new Version(major, minor, build);
-
         DispatcherTimer.RunOnce(
             async () =>
             {
                 try
                 {
-                    await HostUpdateWorkflowServiceProvider
+                    await HostUpdateOrchestratorProvider
                         .GetOrCreate()
-                        .AutoCheckIfEnabledAsync(normalizedVersion);
+                        .AutoCheckIfEnabledAsync(default);
                 }
                 catch (Exception ex)
                 {

LanMountainDesktop/Views/SettingsPages/UpdateSettingsPage.axaml

@@ -1,285 +1,305 @@
-<UserControl xmlns="https://github.com/avaloniaui"
+<UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:vm="using:LanMountainDesktop.ViewModels"
-             xmlns:controls="using:LanMountainDesktop.Controls"
              xmlns:ui="using:FluentAvalonia.UI.Controls"
              xmlns:fi="using:FluentIcons.Avalonia"
              x:Class="LanMountainDesktop.Views.SettingsPages.UpdateSettingsPage"
-             x:DataType="vm:UpdateSettingsPageViewModel">
-    <UserControl.Styles>
-        <Style Selector="Border.update-status-card">
-            <Setter Property="Padding" Value="24" />
-            <Setter Property="Margin" Value="0,0,0,18" />
-            <Setter Property="CornerRadius" Value="{DynamicResource DesignCornerRadiusLg}" />
-            <Setter Property="Background" Value="{DynamicResource AdaptiveSurfaceRaisedBrush}" />
-            <Setter Property="BorderBrush" Value="{DynamicResource AdaptiveGlassPanelBorderBrush}" />
-            <Setter Property="BorderThickness" Value="1" />
-            <Setter Property="BoxShadow" Value="0 6 18 #15000000" />
-        </Style>
+             x:DataType="vm:UpdateSettingsViewModel">
+  <ScrollViewer VerticalScrollBarVisibility="Auto">
+    <StackPanel Classes="settings-page-container settings-page-animated">
+      <StackPanel Spacing="6">
+        <TextBlock Classes="settings-section-title"
+                   Text="Update" />
+        <TextBlock Classes="settings-section-description"
+                   Text="Check for updates, watch download and install progress, and keep the update workflow recoverable from this page." />
+      </StackPanel>
 
-        <Style Selector="TextBlock.update-kv-label">
-            <Setter Property="FontSize" Value="12" />
-            <Setter Property="Opacity" Value="0.68" />
-            <Setter Property="Foreground" Value="{DynamicResource AdaptiveTextPrimaryBrush}" />
-            <Setter Property="TextWrapping" Value="Wrap" />
-            <Setter Property="MaxWidth" Value="200" />
-        </Style>
+      <Border Classes="settings-section-card">
+        <Grid ColumnDefinitions="Auto,*,Auto"
+              ColumnSpacing="16">
+          <Border Classes="settings-section-card-icon-host"
+                  Width="56"
+                  Height="56"
+                  Padding="10">
+            <fi:SymbolIcon Symbol="ArrowSync"
+                           FontSize="22" />
+          </Border>
 
-        <Style Selector="TextBlock.update-kv-value">
-            <Setter Property="FontSize" Value="14" />
-            <Setter Property="FontWeight" Value="SemiBold" />
-            <Setter Property="Foreground" Value="{DynamicResource AdaptiveTextPrimaryBrush}" />
-            <Setter Property="TextWrapping" Value="Wrap" />
-            <Setter Property="MaxWidth" Value="200" />
-            <Setter Property="TextTrimming" Value="CharacterEllipsis" />
-        </Style>
+          <StackPanel Grid.Column="1"
+                      Spacing="6"
+                      VerticalAlignment="Center">
+            <TextBlock Classes="settings-card-header"
+                       Text="Current update status" />
+            <TextBlock Classes="settings-card-description"
+                       Text="The status line below reflects the current update phase and any contextual message returned by the orchestrator." />
+            <TextBlock Text="{Binding StatusMessage}"
+                       TextWrapping="Wrap"
+                       FontSize="22"
+                       FontWeight="SemiBold"
+                       Margin="0,4,0,0" />
+            <StackPanel Orientation="Horizontal"
+                        Spacing="8"
+                        Margin="0,4,0,0">
+              <Border Background="#223D5979"
+                      BorderBrush="#326D8FB7"
+                      BorderThickness="1"
+                      CornerRadius="999"
+                      Padding="10,4">
+                <TextBlock Text="{Binding PhaseText}"
+                           FontSize="12"
+                           FontWeight="SemiBold" />
+              </Border>
+              <Border Background="#223D5979"
+                      BorderBrush="#326D8FB7"
+                      BorderThickness="1"
+                      CornerRadius="999"
+                      Padding="10,4"
+                      IsVisible="{Binding IsUpdateAvailable}">
+                <TextBlock Text="Update available"
+                           FontSize="12"
+                           FontWeight="SemiBold" />
+              </Border>
+              <Border Background="#223D5979"
+                      BorderBrush="#326D8FB7"
+                      BorderThickness="1"
+                      CornerRadius="999"
+                      Padding="10,4"
+                      IsVisible="{Binding IsPaused}">
+                <TextBlock Text="Paused"
+                           FontSize="12"
+                           FontWeight="SemiBold" />
+              </Border>
+            </StackPanel>
+          </StackPanel>
 
-        <Style Selector="TextBlock.update-phase-text">
-            <Setter Property="FontSize" Value="13" />
-            <Setter Property="FontWeight" Value="SemiBold" />
-            <Setter Property="Foreground" Value="{DynamicResource AdaptiveTextPrimaryBrush}" />
-            <Setter Property="TextWrapping" Value="Wrap" />
-        </Style>
-    </UserControl.Styles>
+          <StackPanel Grid.Column="2"
+                      Spacing="10"
+                      VerticalAlignment="Center">
+            <Button Classes="settings-accent-button"
+                    Content="Check for updates"
+                    Command="{Binding CheckCommand}" />
+            <TextBlock Classes="settings-item-description"
+                       Text="{Binding LastCheckedText}"
+                       TextAlignment="Right"
+                       TextWrapping="Wrap"
+                       Width="220" />
+          </StackPanel>
+        </Grid>
+      </Border>
 
-    <ScrollViewer VerticalScrollBarVisibility="Auto">
-        <StackPanel Classes="settings-page-container settings-page-animated">
-            <Border Classes="update-status-card">
-                <StackPanel Spacing="18">
-                    <Grid ColumnDefinitions="Auto,*,Auto"
-                          ColumnSpacing="16">
-                        <Border Classes="settings-section-card-icon-host"
-                                Width="48"
-                                Height="48">
-                            <Viewbox Stretch="Uniform">
-                                <fi:SymbolIcon Symbol="ArrowSync" />
-                            </Viewbox>
-                        </Border>
+      <Border Classes="settings-section-card">
+        <StackPanel Spacing="12">
+          <TextBlock Classes="settings-card-header"
+                     Text="Release facts" />
+          <TextBlock Classes="settings-card-description"
+                     Text="Keep the current version, published release, and update type visible without collapsing the layout while states change." />
 
-                        <StackPanel Grid.Column="1"
-                                    Spacing="4">
-                            <TextBlock Classes="settings-card-header"
-                                       Margin="0"
-                                       Text="{Binding StatusCardTitle}" />
-                            <TextBlock Classes="settings-item-description"
-                                       Text="{Binding StatusCardDescription}" />
-                        </StackPanel>
-
-                        <Button Grid.Column="2"
-                                Classes="settings-accent-button"
-                                Command="{Binding CheckForUpdatesCommand}"
-                                Content="{Binding CheckForUpdatesButtonText}" />
-                    </Grid>
-
-                    <Grid ColumnDefinitions="Auto,*"
-                          RowDefinitions="Auto,Auto,Auto,Auto"
-                          ColumnSpacing="20"
-                          RowSpacing="16">
-                        <StackPanel Grid.Row="0"
-                                    Grid.Column="0"
-                                    Spacing="4">
-                            <TextBlock Classes="update-kv-label"
-                                       Text="{Binding CurrentVersionLabel}" />
-                            <TextBlock Classes="update-kv-value"
-                                       Text="{Binding CurrentVersionText}" />
-                        </StackPanel>
-
-                        <StackPanel Grid.Row="0"
-                                    Grid.Column="1"
-                                    Spacing="4"
-                                    IsVisible="{Binding IsLatestVersionVisible}">
-                            <TextBlock Classes="update-kv-label"
-                                       Text="{Binding LatestVersionLabel}" />
-                            <TextBlock Classes="update-kv-value"
-                                       Text="{Binding LatestVersionText}" />
-                        </StackPanel>
-
-                        <StackPanel Grid.Row="1"
-                                    Grid.Column="0"
-                                    Spacing="4"
-                                    IsVisible="{Binding IsPublishedAtVisible}">
-                            <TextBlock Classes="update-kv-label"
-                                       Text="{Binding PublishedAtLabel}" />
-                            <TextBlock Classes="update-kv-value"
-                                       Text="{Binding PublishedAtText}" />
-                        </StackPanel>
-
-                        <StackPanel Grid.Row="1"
-                                    Grid.Column="1"
-                                    Spacing="4"
-                                    IsVisible="{Binding IsLastCheckedVisible}">
-                            <TextBlock Classes="update-kv-label"
-                                       Text="{Binding LastCheckedLabel}" />
-                            <TextBlock Classes="update-kv-value"
-                                       Text="{Binding LastCheckedText}" />
-                        </StackPanel>
-
-                        <StackPanel Grid.Row="2"
-                                    Grid.Column="0"
-                                    Spacing="4"
-                                    IsVisible="{Binding HasPendingInstaller}">
-                            <TextBlock Classes="update-kv-label"
-                                       Text="{Binding UpdateTypeLabel}" />
-                            <TextBlock Classes="update-kv-value"
-                                       Text="{Binding PendingUpdateTypeText}" />
-                        </StackPanel>
-
-                        <StackPanel Grid.Row="2"
-                                    Grid.Column="1"
-                                    Spacing="4"
-                                    IsVisible="{Binding IsUpdateTypeVisible}">
-                            <TextBlock Classes="update-kv-label"
-                                       Text="{Binding UpdateTypeLabel}" />
-                            <TextBlock Classes="update-kv-value"
-                                       Text="{Binding UpdateTypeText}" />
-                        </StackPanel>
-                    </Grid>
-
-                    <StackPanel Spacing="8"
-                                HorizontalAlignment="Left">
-                        <TextBlock Classes="settings-item-description"
-                                   Text="{Binding UpdateStatus}"
-                                   TextWrapping="Wrap"
-                                   HorizontalAlignment="Left"
-                                   MaxWidth="500" />
-
-                        <TextBlock Classes="update-phase-text"
-                                   IsVisible="{Binding IsDownloadProgressVisible}"
-                                   Text="{Binding UpdatePhaseText}"
-                                   TextWrapping="Wrap"
-                                   HorizontalAlignment="Left" />
-
-                        <ProgressBar Minimum="0"
-                                     Maximum="100"
-                                     Value="{Binding PhaseProgressValue}"
-                                     IsVisible="{Binding IsDownloadProgressVisible}"
-                                     HorizontalAlignment="Stretch"
-                                     Margin="0,4,0,4"
-                                     ShowProgressText="True" />
-
-                        <TextBlock Classes="settings-item-description"
-                                   IsVisible="{Binding IsDownloadProgressVisible}"
-                                   Text="{Binding DownloadProgressText}"
-                                   TextWrapping="Wrap"
-                                   HorizontalAlignment="Left"
-                                   Margin="0,4,0,0" />
-                    </StackPanel>
-
-                    <StackPanel Orientation="Horizontal"
-                                Spacing="10">
-                        <Button Command="{Binding DownloadLatestReleaseCommand}"
-                                IsVisible="{Binding IsDownloadButtonVisible}">
-                            <StackPanel Orientation="Horizontal" Spacing="8">
-                                <fi:SymbolIcon Symbol="ArrowDownload" FontSize="14" />
-                                <TextBlock Text="{Binding DownloadButtonText}" VerticalAlignment="Center" />
-                            </StackPanel>
-                        </Button>
-                        <Button Command="{Binding RedownloadUpdateCommand}"
-                                IsVisible="{Binding IsRedownloadButtonVisible}">
-                            <StackPanel Orientation="Horizontal" Spacing="8">
-                                <fi:SymbolIcon Symbol="ArrowUndo" FontSize="14" />
-                                <TextBlock Text="{Binding RedownloadButtonText}" VerticalAlignment="Center" />
-                            </StackPanel>
-                        </Button>
-                        <Button Classes="settings-accent-button"
-                                Command="{Binding InstallPendingUpdateCommand}"
-                                IsVisible="{Binding IsInstallButtonVisible}">
-                            <StackPanel Orientation="Horizontal" Spacing="8">
-                                <fi:SymbolIcon Symbol="Play" FontSize="14" />
-                                <TextBlock Text="{Binding InstallNowButtonText}" VerticalAlignment="Center" />
-                            </StackPanel>
-                        </Button>
-                    </StackPanel>
-                </StackPanel>
+          <Grid RowDefinitions="Auto,Auto,Auto"
+                ColumnDefinitions="*,*"
+                ColumnSpacing="12"
+                RowSpacing="12">
+            <Border Classes="settings-list-item">
+              <StackPanel Classes="settings-item">
+                <TextBlock Classes="settings-item-label"
+                           Text="Current version" />
+                <TextBlock Classes="settings-item-description"
+                           Text="{Binding CurrentVersionText}"
+                           TextWrapping="Wrap" />
+              </StackPanel>
             </Border>
 
-            <TextBlock Classes="settings-subsection-title"
-                       Text="{Binding PreferencesHeader}" />
-            <TextBlock Classes="settings-section-description"
-                       Margin="0,0,0,18"
-                       Text="{Binding PreferencesDescription}" />
+            <Border Grid.Column="1"
+                    Classes="settings-list-item">
+              <StackPanel Classes="settings-item">
+                <TextBlock Classes="settings-item-label"
+                           Text="Latest version" />
+                <TextBlock Classes="settings-item-description"
+                           Text="{Binding LatestVersionText}"
+                           TextWrapping="Wrap" />
+              </StackPanel>
+            </Border>
 
-            <ui:FASettingsExpander Classes="settings-expander-card"
-                                 Header="{Binding UpdateChannelLabel}"
-                                 Description="{Binding SelectedUpdateChannelDescription}">
-                <ui:FASettingsExpander.IconSource>
-                    <ui:FAFontIconSource Glyph="&#xF06C8;" FontFamily="avares://fluenticons.resources.avalonia/Assets#Seagull Fluent Icons" />
-                </ui:FASettingsExpander.IconSource>
-                <ui:FASettingsExpander.Footer>
-                    <ComboBox Width="220"
-                              ItemsSource="{Binding UpdateChannelOptions}"
-                              SelectedItem="{Binding SelectedUpdateChannelOption}">
-                        <ComboBox.ItemTemplate>
-                            <DataTemplate>
-                                <TextBlock Text="{Binding Label}" />
-                            </DataTemplate>
-                        </ComboBox.ItemTemplate>
-                    </ComboBox>
-                </ui:FASettingsExpander.Footer>
-                <ui:FASettingsExpanderItem Content="{Binding ForceCheckUpdateLabel}"
-                                         Description="{Binding ForceCheckUpdateDescription}"
-                                         IsClickEnabled="True"
-                                         Command="{Binding ForceCheckUpdateCommand}">
-                    <ui:FASettingsExpanderItem.IconSource>
-                        <ui:FAFontIconSource Glyph="&#xF0FD4;" FontFamily="avares://fluenticons.resources.avalonia/Assets#Seagull Fluent Icons" />
-                    </ui:FASettingsExpanderItem.IconSource>
-                </ui:FASettingsExpanderItem>
-                <ui:FASettingsExpanderItem Content="{Binding ForceFullUpdateLabel}"
-                                         Description="{Binding ForceFullUpdateDescription}"
-                                         IsClickEnabled="True"
-                                         Command="{Binding ForceFullUpdateCommand}">
-                    <ui:FASettingsExpanderItem.IconSource>
-                        <ui:FAFontIconSource Glyph="&#xF0E9F;" FontFamily="avares://fluenticons.resources.avalonia/Assets#Seagull Fluent Icons" />
-                    </ui:FASettingsExpanderItem.IconSource>
-                </ui:FASettingsExpanderItem>
-            </ui:FASettingsExpander>
-
-            <ui:FASettingsExpander Classes="settings-expander-card"
-                                 Header="{Binding UpdateModeLabel}"
-                                 Description="{Binding SelectedUpdateModeDescription}">
-                <ui:FASettingsExpander.IconSource>
-                    <ui:FAFontIconSource Glyph="&#xF06FC;" FontFamily="avares://fluenticons.resources.avalonia/Assets#Seagull Fluent Icons" />
-                </ui:FASettingsExpander.IconSource>
-                <ui:FASettingsExpander.Footer>
-                    <ComboBox Width="260"
-                              ItemsSource="{Binding UpdateModeOptions}"
-                              SelectedItem="{Binding SelectedUpdateModeOption}">
-                        <ComboBox.ItemTemplate>
-                            <DataTemplate>
-                                <TextBlock Text="{Binding Label}" />
-                            </DataTemplate>
-                        </ComboBox.ItemTemplate>
-                    </ComboBox>
-                </ui:FASettingsExpander.Footer>
-            </ui:FASettingsExpander>
-
-            <ui:FASettingsExpander Classes="settings-expander-card"
-                                 Header="{Binding NetworkAccelerationLabel}"
-                                 Description="{Binding NetworkAccelerationDescription}">
-                <ui:FASettingsExpander.IconSource>
-                    <ui:FAFontIconSource Glyph="&#xF01BB;" FontFamily="avares://fluenticons.resources.avalonia/Assets#Seagull Fluent Icons" />
-                </ui:FASettingsExpander.IconSource>
-                <ui:FASettingsExpander.Footer>
-                    <ToggleSwitch IsChecked="{Binding UseGhProxyMirror}" />
-                </ui:FASettingsExpander.Footer>
-            </ui:FASettingsExpander>
-
-            <ui:FASettingsExpander Classes="settings-expander-card"
-                                 Header="{Binding DownloadThreadsLabel}"
-                                 Description="{Binding DownloadThreadsDescription}">
-                <ui:FASettingsExpander.IconSource>
-                    <ui:FAFontIconSource Glyph="&#xF06C0;" FontFamily="avares://fluenticons.resources.avalonia/Assets#Seagull Fluent Icons" />
-                </ui:FASettingsExpander.IconSource>
-                <ui:FASettingsExpander.Footer>
-                    <ui:FANumberBox Width="160"
-                                  Minimum="1"
-                                  Maximum="128"
-                                  SpinButtonPlacementMode="Inline"
-                                  Value="{Binding DownloadThreadsSliderValue}" />
-                </ui:FASettingsExpander.Footer>
-            </ui:FASettingsExpander>
+            <Border Grid.Row="1"
+                    Classes="settings-list-item">
+              <StackPanel Classes="settings-item">
+                <TextBlock Classes="settings-item-label"
+                           Text="Published at" />
+                <TextBlock Classes="settings-item-description"
+                           Text="{Binding PublishedAtText}"
+                           TextWrapping="Wrap" />
+              </StackPanel>
+            </Border>
 
+            <Border Grid.Row="1"
+                    Grid.Column="1"
+                    Classes="settings-list-item">
+              <StackPanel Classes="settings-item">
+                <TextBlock Classes="settings-item-label"
+                           Text="Last checked" />
+                <TextBlock Classes="settings-item-description"
+                           Text="{Binding LastCheckedText}"
+                           TextWrapping="Wrap" />
+              </StackPanel>
+            </Border>
 
+            <Border Grid.Row="2"
+                    Grid.ColumnSpan="2"
+                    Classes="settings-list-item">
+              <StackPanel Classes="settings-item">
+                <TextBlock Classes="settings-item-label"
+                           Text="Update type" />
+                <TextBlock Classes="settings-item-description"
+                           Text="{Binding UpdateTypeText}"
+                           TextWrapping="Wrap" />
+              </StackPanel>
+            </Border>
+          </Grid>
         </StackPanel>
-    </ScrollViewer>
+      </Border>
+
+      <Border Classes="settings-section-card">
+        <StackPanel Spacing="12">
+          <TextBlock Classes="settings-card-header"
+                     Text="Progress" />
+          <TextBlock Classes="settings-card-description"
+                     Text="Watch download, installation, verification, and recovery progress here." />
+
+          <StackPanel Spacing="10">
+            <Grid ColumnDefinitions="*,Auto"
+                  ColumnSpacing="12">
+              <TextBlock Classes="settings-item-label"
+                         Text="{Binding PhaseText}" />
+              <TextBlock Classes="settings-item-description"
+                         Text="{Binding ProgressFraction, StringFormat='{}{0:P0}'}"
+                         HorizontalAlignment="Right" />
+            </Grid>
+
+            <ProgressBar Minimum="0"
+                         Maximum="1"
+                         Value="{Binding ProgressFraction}"
+                         Height="12"
+                         IsVisible="{Binding IsProgressVisible}" />
+
+            <TextBlock Classes="settings-item-description"
+                       Text="{Binding ProgressDetail}"
+                       TextWrapping="Wrap" />
+
+            <Border Background="#223D5979"
+                    BorderBrush="#326D8FB7"
+                    BorderThickness="1"
+                    CornerRadius="10"
+                    Padding="12"
+                    IsVisible="{Binding IsPaused}">
+              <TextBlock Classes="settings-item-description"
+                         Text="Paused. Resume to continue from the current state." />
+            </Border>
+          </StackPanel>
+        </StackPanel>
+      </Border>
+
+      <Border Classes="settings-section-card">
+        <StackPanel Spacing="12">
+          <TextBlock Classes="settings-card-header"
+                     Text="Actions" />
+          <TextBlock Classes="settings-card-description"
+                     Text="The buttons below stay in place while the update phase changes, so the page does not jump around." />
+
+          <Grid ColumnDefinitions="*,*,*"
+                RowDefinitions="Auto,Auto,Auto"
+                ColumnSpacing="12"
+                RowSpacing="10">
+            <Button Classes="settings-accent-button"
+                    Content="Check"
+                    Command="{Binding CheckCommand}" />
+            <Button Grid.Column="1"
+                    Content="Download"
+                    Command="{Binding DownloadCommand}" />
+            <Button Grid.Column="2"
+                    Content="Install"
+                    Command="{Binding InstallCommand}" />
+
+            <Button Grid.Row="1"
+                    Content="Pause"
+                    Command="{Binding PauseCommand}" />
+            <Button Grid.Row="1"
+                    Grid.Column="1"
+                    Content="Resume"
+                    Command="{Binding ResumeCommand}" />
+            <Button Grid.Row="1"
+                    Grid.Column="2"
+                    Content="Rollback"
+                    Command="{Binding RollbackCommand}" />
+
+            <Button Grid.Row="2"
+                    Grid.ColumnSpan="3"
+                    Content="Cancel"
+                    Command="{Binding CancelCommand}" />
+          </Grid>
+        </StackPanel>
+      </Border>
+
+      <ui:FASettingsExpander Classes="settings-expander-card"
+                             Header="Update preferences"
+                             Description="Choose the update channel, download source, mode, and thread count without leaving this page.">
+        <ui:FASettingsExpander.IconSource>
+          <ui:FAFontIconSource Glyph="&#xF0504;"
+                               FontFamily="avares://fluenticons.resources.avalonia/Assets#Seagull Fluent Icons" />
+        </ui:FASettingsExpander.IconSource>
+        <ui:FASettingsExpanderItem>
+          <StackPanel Spacing="12">
+            <Grid ColumnDefinitions="180,*"
+                  RowDefinitions="Auto,Auto,Auto,Auto"
+                  RowSpacing="10"
+                  ColumnSpacing="12">
+              <TextBlock Grid.Row="0"
+                         Classes="settings-item-label"
+                         Text="Channel"
+                         VerticalAlignment="Center" />
+              <TextBox Grid.Row="0"
+                       Grid.Column="1"
+                       Text="{Binding SelectedUpdateChannelValue}"
+                       Watermark="stable / preview" />
+
+              <TextBlock Grid.Row="1"
+                         Classes="settings-item-label"
+                         Text="Source"
+                         VerticalAlignment="Center" />
+              <TextBox Grid.Row="1"
+                       Grid.Column="1"
+                       Text="{Binding SelectedUpdateSourceValue}"
+                       Watermark="plonds / github / proxy" />
+
+              <TextBlock Grid.Row="2"
+                         Classes="settings-item-label"
+                         Text="Mode"
+                         VerticalAlignment="Center" />
+              <TextBox Grid.Row="2"
+                       Grid.Column="1"
+                       Text="{Binding SelectedUpdateModeValue}"
+                       Watermark="manual / confirm / silent" />
+
+              <TextBlock Grid.Row="3"
+                         Classes="settings-item-label"
+                         Text="Download threads"
+                         VerticalAlignment="Center" />
+              <StackPanel Grid.Row="3"
+                          Grid.Column="1"
+                          Orientation="Horizontal"
+                          Spacing="8">
+                <Slider Width="220"
+                        Minimum="1"
+                        Maximum="16"
+                        Value="{Binding DownloadThreadsSliderValue}"
+                        TickFrequency="1"
+                        IsSnapToTickEnabled="True" />
+                <TextBlock Classes="settings-item-label"
+                           Text="{Binding DownloadThreadsSliderValue, StringFormat='{}{0:F0}'}"
+                           VerticalAlignment="Center" />
+              </StackPanel>
+            </Grid>
+          </StackPanel>
+        </ui:FASettingsExpanderItem>
+      </ui:FASettingsExpander>
+    </StackPanel>
+  </ScrollViewer>
 </UserControl>

LanMountainDesktop/Views/SettingsPages/UpdateSettingsPage.axaml.cs

@@ -1,5 +1,6 @@
 using LanMountainDesktop.PluginSdk;
 using LanMountainDesktop.Services.Settings;
+using LanMountainDesktop.Services.Update;
 using LanMountainDesktop.ViewModels;
 
 namespace LanMountainDesktop.Views.SettingsPages;
@@ -15,16 +16,18 @@ namespace LanMountainDesktop.Views.SettingsPages;
 public partial class UpdateSettingsPage : SettingsPageBase
 {
     public UpdateSettingsPage()
-        : this(new UpdateSettingsPageViewModel(HostSettingsFacadeProvider.GetOrCreate()))
+        : this(new UpdateSettingsViewModel(
+            HostUpdateOrchestratorProvider.GetOrCreate(),
+            HostSettingsFacadeProvider.GetOrCreate()))
     {
     }
 
-    public UpdateSettingsPage(UpdateSettingsPageViewModel viewModel)
+    public UpdateSettingsPage(UpdateSettingsViewModel viewModel)
     {
         ViewModel = viewModel;
         DataContext = ViewModel;
         InitializeComponent();
     }
 
-    public UpdateSettingsPageViewModel ViewModel { get; }
+    public UpdateSettingsViewModel ViewModel { get; }
 }

LanMountainDesktop/Views/TransparentOverlayWindow.axaml

@@ -7,16 +7,55 @@
         ExtendClientAreaToDecorationsHint="True"
         Background="Transparent"
         Title="LanMountainDesktop Fused Desktop">
-    <!--
-        融合桌面（负一屏）- 在系统桌面上显示组件
+    <Window.Styles>
+        <Style Selector="Border.fused-desktop-component-host">
+            <Setter Property="Background" Value="Transparent" />
+            <Setter Property="BorderBrush" Value="Transparent" />
+            <Setter Property="BorderThickness" Value="0" />
+            <Setter Property="CornerRadius" Value="{DynamicResource DesignCornerRadiusComponent}" />
+        </Style>
+        <Style Selector="Border.fused-desktop-component-host.selected">
+            <Setter Property="BorderBrush" Value="{DynamicResource AdaptiveAccentBrush}" />
+            <Setter Property="BorderThickness" Value="2" />
+        </Style>
+        <Style Selector="Border.fused-desktop-resize-handle">
+            <Setter Property="Background" Value="{DynamicResource AdaptiveAccentBrush}" />
+            <Setter Property="BorderBrush" Value="{DynamicResource AdaptiveGlassPanelBorderBrush}" />
+            <Setter Property="BorderThickness" Value="1" />
+            <Setter Property="CornerRadius" Value="{DynamicResource DesignCornerRadiusSm}" />
+        </Style>
+        <Style Selector="Border.fused-desktop-edit-toolbar">
+            <Setter Property="Background" Value="{DynamicResource AdaptiveDockGlassBackgroundBrush}" />
+            <Setter Property="BorderBrush" Value="{DynamicResource AdaptiveDockGlassBorderBrush}" />
+            <Setter Property="BorderThickness" Value="1" />
+            <Setter Property="CornerRadius" Value="{DynamicResource DesignCornerRadiusIsland}" />
+        </Style>
+    </Window.Styles>
 
-        特性：
-        - 窗口置底（在桌面图标层显示）
-        - 区域级穿透（组件区域可交互，其他区域穿透）
-        - 组件可自由拖拽摆放
-        - 三指/右键左滑回到阗山桌面第一页
-    -->
-    <Canvas x:Name="ComponentCanvas">
-        <!-- 组件将动态添加到这里 -->
-    </Canvas>
+    <Grid x:Name="OverlayRoot">
+        <Canvas x:Name="ComponentCanvas"
+                Background="#01000000"
+                PointerPressed="OnCanvasPointerPressed" />
+
+        <Border x:Name="EditToolbar"
+                Classes="fused-desktop-edit-toolbar"
+                HorizontalAlignment="Center"
+                VerticalAlignment="Bottom"
+                Margin="0,0,0,20"
+                Padding="8"
+                IsHitTestVisible="True">
+            <StackPanel Orientation="Horizontal" Spacing="8">
+                <Button MinWidth="112"
+                        Padding="16,8"
+                        Click="OnRestoreComponentLibraryClick">
+                    <TextBlock Text="找回组件库" />
+                </Button>
+                <Button MinWidth="96"
+                        Padding="16,8"
+                        Click="OnExitEditClick">
+                    <TextBlock Text="退出编辑" />
+                </Button>
+            </StackPanel>
+        </Border>
+    </Grid>
 </Window>