LanMountainDesktop/.trae/specs/pdc-incremental-migration/spec.md

PDC Incremental Update Migration

Goal

Replace VeloPack-based incremental packaging with a unified PDC FileMap + object-repo pipeline, while keeping Launcher installation, rollback, and update orchestration ownership unchanged.

Stage 1 (Completed)

• Release workflow removed VeloPack-based release packaging.
• Signed FileMap path was restored as an interim release mechanism.
• Host/Launcher fallback behavior stayed compatible with files.json + files.json.sig + update.zip.

Stage 2 (Current Implementation Target)

• Move release publishing to PDCC + phainon.yml (ClassIsland-style).
• Promote PDC-distributed FileMap/object-repo as the primary incremental path.
• Keep GitHub Release installers and metadata as parallel distribution.
• Keep Launcher state machine ownership (.current/.partial/.destroy + snapshots).
• Update source defaults to stcn (S3/PDC), with GitHub fallback.
• S3 object root is fixed to lanmountain/update/ with no update-system version prefix.

Expected S3 layout:

• lanmountain/update/repo/<hash-prefix>/<hash-object>
• lanmountain/update/meta/channels/<channel>/<subchannel>/latest.json
• lanmountain/update/meta/distributions/<distributionId>/*.json
• lanmountain/update/installers/<platform>/<arch>/*

Acceptance

• release.yml includes PDCC publish steps and no Velopack steps.
• Release jobs keep building installers for Windows x64/x86, Linux x64, and macOS.
• PDC metadata + FileMap + object repo are published under lanmountain/update/.
• Host can consume PDC payload (stcn source) and fallback to GitHub when unavailable.
• Launcher can apply both:
  • legacy signed files.json + update.zip
  • PDC FileMap object-repo payload.
• Rollback semantics remain unchanged.

Deprecated Notes

• The following interim outputs are compatibility-only (not the long-term primary path):
  • files-windows-x64.json / .sig / update-windows-x64.zip
  • files-windows-x86.json / .sig / update-windows-x86.zip
  • files-linux-x64.json / .sig / update-linux-x64.zip