## Summary
Adds the version-subscription drift detection and operator-apply workflow for
per-workspace plugin tracking (core#113).
## Components
**Migration** (`20260510000000_plugin_drift_queue`):
- Adds `installed_sha` column to `workspace_plugins` — records the commit SHA
installed so the drift sweeper can compare against upstream.
- Creates `plugin_update_queue` table with status: pending | applied | dismissed.
- Adds partial unique index to prevent duplicate pending rows per
(workspace_id, plugin_name).
**GithubResolver** (`github.go`):
- `LastFetchSHA` field + `LastSHA()` getter — populated by `Fetch` after a
successful shallow clone (captured before `.git` is stripped). Used by the
install pipeline to seed `installed_sha`.
- `ResolveRef(ctx, spec)` method — resolves a plugin spec to its full commit
SHA using `git fetch --depth=1 + git rev-parse`. Used by the drift sweeper
to get the current upstream SHA for a tracked ref (tag:vX.Y.Z, tag:latest,
sha:…, or bare branch).
**Drift sweeper** (`plugins/drift_sweeper.go`):
- Periodic sweep every 1h: SELECTs rows where `tracked_ref != 'none' AND
installed_sha IS NOT NULL`, resolves upstream SHA, queues drift if different.
- `ListPendingUpdates()` — reads pending queue rows for the admin endpoint.
- `ApplyDriftUpdate()` — marks entry applied (idempotent).
- ctx.Err() guard on ticker arm to avoid post-shutdown work.
**Install pipeline** (`plugins_install_pipeline.go`, `plugins_tracking.go`,
`plugins_install.go`):
- `stageResult.InstalledSHA` field — carries the SHA from Fetch to the DB.
- `recordWorkspacePluginInstall` now accepts and stores `installed_sha`.
- `deleteWorkspacePluginRow` — removes tracking row on uninstall so a stale
SHA doesn't prevent the next install from creating a fresh row.
- Both Docker and EIC uninstall paths call `deleteWorkspacePluginRow`.
**Admin endpoints** (`handlers/admin_plugin_drift.go`):
- `GET /admin/plugin-updates-pending` — list all pending drift entries.
- `POST /admin/plugin-updates/:id/apply` — re-installs plugin from source_raw
(re-fetching the same tracked ref), records the new SHA, marks entry applied,
triggers workspace restart. Idempotent (already-applied returns 200).
**Router wiring** (`router.go`, `cmd/server/main.go`):
- Plugin registry created in main.go and shared between PluginsHandler and drift
sweeper.
- `router.Setup` accepts optional `pluginResolver` param.
- `PluginsHandler.Sources()` export for the sweeper wiring pattern.
## Tests
- `plugins/github_test.go` — `ResolveRef` coverage (invalid spec, git error,
not-found mapping, no-panic for all ref shapes).
- `plugins/drift_sweeper_test.go` — `ResolveRef` happy path, stub resolver
interface compliance.
- `handlers/admin_plugin_drift_test.go` — ListPending (empty, non-empty, DB
error), Apply (not found, already applied, already dismissed, workspace_plugins
missing).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
