Plan: Write AGENTS.md learnings via PR instead of direct commit#

Summary#

Replace CompoundService.writeLearnings() direct Contents API write with a branch + PR + auto-merge flow. The current createOrUpdateFile() call fails with 409 on branch-protected repos because GitHub App tokens respect protection rules (unlike the old PAT admin bypass). The compound-learnings skill (SKILL.md) already uses the PR path — this aligns the server-side hook to match.

Files#

File	Action	Description
`src/hooks/compound.service.ts`	modify	Replace `createOrUpdateFile()` with `createBranch()` + `createOrUpdateFile(branch)` + `createPR()` + `enableAutoMerge()` flow
`src/github/github.service.ts`	modify	Add `createBranch()` and `enableAutoMerge()` methods (both missing from the service)
`src/github/github.service.spec.ts`	modify	Add unit tests for new `createBranch()` and `enableAutoMerge()` methods
`src/hooks/compound.service.spec.ts`	modify	Update tests to verify branch+PR flow instead of direct `createOrUpdateFile` on default branch
`.claude/skills/compound-learnings/SKILL.md`	inspect	Already uses PR path — verify no conditional branching on repo type remains

Steps#

Add createBranch(owner, repo, branchName, fromSha) to GitHubService — calls POST /repos/{owner}/{repo}/git/refs with refs/heads/{branchName} from the given SHA. Handle 422 (branch exists) by deleting and recreating.
Add enableAutoMerge(owner, repo, prNumber) to GitHubService — uses GraphQL enablePullRequestAutoMerge mutation with SQUASH merge method.
Add getDefaultBranchSha(owner, repo) to GitHubService — calls GET /repos/{owner}/{repo} and reads default_branch, then resolves its HEAD SHA via GET /repos/{owner}/{repo}/git/ref/heads/{branch}.
Refactor CompoundService.writeLearnings(): after building the AGENTS.md content, call getDefaultBranchSha() → createBranch() (branch name: agents-md/issue-{issueNumber}) → createOrUpdateFile() targeting the new branch → createPR() → enableAutoMerge(). Remove the direct-to-default-branch createOrUpdateFile() call.
Update compound.service.spec.ts: mock createBranch, getDefaultBranchSha, createPR, enableAutoMerge on GitHubService; verify the PR flow is called instead of direct commit; cover edge cases (branch already exists, no existing AGENTS.md).
Add unit tests for createBranch, enableAutoMerge, getDefaultBranchSha in github.service.spec.ts.

Verification#

npm run test passes — all new and updated unit tests green
npm run lint passes with zero warnings
npm run build compiles without errors

Risks#

Auto-merge requires repo setting enabled: enableAutoMerge fails if the repo doesn't have "Allow auto-merge" enabled in settings. Mitigation: catch and log the error, fall back gracefully (PR stays open for manual merge).
Branch name collision: A stale branch from a prior failed run could block creation. Mitigation: delete existing branch before creating (same pattern as the compound-learnings skill).

Summary#

Files#

File	Action	Description
`src/hooks/compound.service.ts`	modify	Replace `createOrUpdateFile()` with `createBranch()` + `createOrUpdateFile(branch)` + `createPR()` + `enableAutoMerge()` flow
`src/github/github.service.ts`	modify	Add `createBranch()` and `enableAutoMerge()` methods (both missing from the service)
`src/github/github.service.spec.ts`	modify	Add unit tests for new `createBranch()` and `enableAutoMerge()` methods
`src/hooks/compound.service.spec.ts`	modify	Update tests to verify branch+PR flow instead of direct `createOrUpdateFile` on default branch
`.claude/skills/compound-learnings/SKILL.md`	inspect	Already uses PR path — verify no conditional branching on repo type remains

Steps#

Add createBranch(owner, repo, branchName, fromSha) to GitHubService — calls POST /repos/{owner}/{repo}/git/refs with refs/heads/{branchName} from the given SHA. Handle 422 (branch exists) by deleting and recreating.

Add enableAutoMerge(owner, repo, prNumber) to GitHubService — uses GraphQL enablePullRequestAutoMerge mutation with SQUASH merge method.

Add getDefaultBranchSha(owner, repo) to GitHubService — calls GET /repos/{owner}/{repo} and reads default_branch, then resolves its HEAD SHA via GET /repos/{owner}/{repo}/git/ref/heads/{branch}.

Refactor CompoundService.writeLearnings(): after building the AGENTS.md content, call getDefaultBranchSha() → createBranch() (branch name: agents-md/issue-{issueNumber}) → createOrUpdateFile() targeting the new branch → createPR() → enableAutoMerge(). Remove the direct-to-default-branch createOrUpdateFile() call.

Update compound.service.spec.ts: mock createBranch, getDefaultBranchSha, createPR, enableAutoMerge on GitHubService; verify the PR flow is called instead of direct commit; cover edge cases (branch already exists, no existing AGENTS.md).

Add unit tests for createBranch, enableAutoMerge, getDefaultBranchSha in github.service.spec.ts.

Risks#

Auto-merge requires repo setting enabled: enableAutoMerge fails if the repo doesn't have "Allow auto-merge" enabled in settings. Mitigation: catch and log the error, fall back gracefully (PR stays open for manual merge).

Branch name collision: A stale branch from a prior failed run could block creation. Mitigation: delete existing branch before creating (same pattern as the compound-learnings skill).