Plan: Compound Phase Merged-PR Guard & Docs-Only Validation#

Summary#

Add a pre-compound guard in PhaseRouterService that blocks compound execution until task.prNumber is confirmed merged via the GitHub API, and add post-compound diff validation in PhaseRouterService that rejects compound output touching src/ or test/ files (retry once, then BLOCKED:PERSISTENT).

Files#

File	Action	Description
`src/github/github.service.ts`	modify	Add `isPrMerged(owner, repo, prNumber)` method
`src/github/github.service.spec.ts`	modify	Add tests for `isPrMerged`
`src/phase-router/phase-router.service.ts`	modify	Add pre-compound merged-PR guard and post-compound diff validation
`src/phase-router/phase-router.service.spec.ts`	modify	Add tests for compound guards (null prNumber, PR not merged, diff validation)
`src/internal-adapter/internal-adapter.service.ts`	modify	Add compound-specific advancement logic in `advanceAndEnqueue` — only enqueue compound when PR is merged

Steps#

Add isPrMerged to GitHubService — call GET /repos/{owner}/{repo}/pulls/{prNumber} and return data.merged === true. Handle 404 as false.
Add merged-PR guard in PhaseRouterService.executePhase — before executing compound, check task.prNumber. If null, signal BLOCKED:PERSISTENT with "compound reached with no PR on record". If set, call isPrMerged; if not merged, signal BLOCKED:TRANSIENT with "PR not yet merged".
Add post-compound diff validation in PhaseRouterService.executePhase — after compound completes, run git diff --name-only origin/master...HEAD in the worktree. If any path starts with src/ or test/, set a retry flag. On first violation, re-invoke compound with an explicit docs-only constraint env var. On second violation, signal BLOCKED:PERSISTENT.
Update advanceAndEnqueue in InternalAdapterService — when advancing from deliver to compound, check that task.prNumber is set before enqueuing (fail-fast guard, complementing the runtime check in step 2).
Write unit tests — cover: (a) isPrMerged happy/404, (b) compound blocked on null prNumber, (c) compound blocked on open PR, (d) compound proceeds on merged PR, (e) diff validation retry and persistent block.

Verification#

npm run test passes with new tests covering all compound guard paths
npm run lint passes with zero warnings
Manual trace: deliver_completed → compound enqueue only fires when prNumber is merged

Risks#

Race condition: PR merge webhook and compound advancement could race. Mitigation: the runtime guard in executePhase is the authoritative check; the advanceAndEnqueue guard is a fail-fast optimization.
Compound worktree: compound currently has no worktree (not in WORKTREE_PHASES). The diff validation needs access to the git state — will use the artefacts repo or PROJECT_ROOT env var instead.