feat(gastown): babysit existing PR feature

[jrf0110]

Summary

Adds the "babysit existing PR" feature to Gastown, allowing towns to adopt and manage external PRs (created manually, by other tools, or by third parties). The town polls the PR, addresses review feedback, fixes merge conflicts, and auto-merges — bypassing the refinery code review path since the user is opting into "merge this PR", not "review this PR".

Key changes across 4 chunks:

• Chunk 0 (Town DO): slingExistingPr and previewPr methods on TownDO — validates PR URL against rig repo, checks PR status via SCM, creates a merge_request bead with gt:babysit label and babysit metadata (head_sha, force_push_allowed)
• Chunk 1 (tRPC + HTTP): babysitPr and previewPr tRPC mutations + POST /api/mayor/:townId/tools/babysit-pr HTTP handler for mayor tool access
• Chunk 2 (Mayor tool + force-push gate): gt_babysit_pr mayor tool, force_push_allowed metadata propagated through pr_fixup_context/pr_conflict_context in prime context, polecat prompt updated with force-push policy (default false for babysat PRs = merge-only, no history rewriting)
• Chunk 3 (SlingDialog + UI): SlingDialog babysit-PR mode, BeadPanel babysit badge and metadata display, eventDescription extracted to module with babysit event types, buildRelatedBeads extracted for testability, ActivityFeed icons/colors for babysit events, Gastown platform filter in sessions UI

Also includes infrastructure improvements:

• Container env var refactor: Removes setEnvVar/deleteEnvVar from TownContainerDO in favor of passing config through control server request protocol (/sync-config, /refresh-token, /agents/start). Eliminates stale persisted env var issues across DO evictions and container restarts.
• Mayor cold start optimization: Backgrounds browse worktree setup, logs timing metrics for workspace creation and AGENTS.md writes
• Boot hydration optimization: Prioritizes mayor resume over non-mayor agents, uses Zod validation for registry entries, defers non-mayor resumes
• SDK bump: @kilocode/sdk 7.2.14 → 7.3.1, @kilocode/cli 7.2.14 → 7.3.1
• Container max instances: 500 → 700

Verification

• Tested babysit PR flow via mayor tool in staging environment
• Verified babysat PR beads bypass refinery and fast-track to in_progress in reconciler
• Verified force_push_allowed: false polecats use merge commits (no force-push)
• Verified PR URL repo validation rejects cross-repo adoption
• Verified previewPr returns correct metadata for GitHub and GitLab PRs

Visual Changes

• Babysit badge ("Babysat external PR" with eye icon) on merge_request beads in BeadPanel
• Babysit metadata section: Head SHA (linked to commit), Force-push status, Babysit started timestamp
• New event icons/colors in ActivityFeed for babysit-related events
• "Gastown" platform filter added to Cloud Agent sessions sidebar

Reviewer Notes

• The slingExistingPr method in TownDO has duplicated PR URL parsing logic with previewPr — this is intentional to keep previewPr as a lightweight read-only path that can fail independently
• The force_push_allowed gate defaults to true when absent (backwards compat for pre-babysit beads) — only explicit false disables force-push
• The container env var refactor (removing setEnvVar/deleteEnvVar) is a significant infra change that removes the persisted env var store in favor of always-fresh request-scoped delivery. This eliminates stale-token bugs across DO evictions
• 173 commits on this branch include many prior staging commits that have already been reviewed/merged separately

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Executive Summary

The duplicate const isBabysit declaration in BeadPanel.tsx has been removed — all previously flagged issues are now resolved.

Resolved Issues

File	Line	Issue	Status
apps/web/src/components/gastown/drawer-panels/BeadPanel.tsx	259 (old)	Duplicate const isBabysit declaration causing TypeScript compile error	✅ Fixed — duplicate removed in commit 324444b0c
apps/web/src/components/gastown/drawer-panels/BeadPanel.tsx	245	isBabysit used before declaration (TDZ)	✅ Fixed — declaration moved to line 239, before first use
apps/web/src/components/gastown/drawer-panels/BeadPanel.tsx	561	babysit_started_at displayed without data	✅ Fixed — review-queue.ts now writes the value
apps/web/src/app/admin/gastown/towns/[townId]/beads/[beadId]/BeadInspectorDashboard.tsx	297	Same babysit_started_at display issue	✅ Fixed — same upstream fix

Files Reviewed (7 files)

• apps/web/src/components/gastown/drawer-panels/BeadPanel.tsx — all issues resolved
• apps/web/src/app/admin/gastown/towns/[townId]/beads/[beadId]/BeadInspectorDashboard.tsx — no issues
• services/gastown/src/dos/Town.do.ts — no issues
• services/gastown/src/dos/town/review-queue.ts — no issues
• services/gastown/test/unit/babysit-pr-helpers.ts — no issues
• services/gastown/test/unit/babysit-pr.test.ts — no issues
• services/gastown/test/unit/sling-existing-pr.test.ts — no issues

---

_{Reviewed by claude-sonnet-4.6 · 191,127 tokens}

_{Review guidance: REVIEW.md from base branch gastown-staging}