story-kit: accept 154_bug_mergemaster_quality_gates_fail_because_merge_worktree_has_no_frontend_deps

.story_kit/work/6_archived/154_bug_mergemaster_quality_gates_fail_because_merge_worktree_has_no_frontend_deps.md

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+---
+name: "Mergemaster quality gates fail because merge worktree has no frontend dependencies"
+---
+
+# Bug 154: Mergemaster quality gates always fail — merge worktree missing frontend deps
+
+## Description
+
+`run_squash_merge()` in `server/src/agents.rs` creates an ephemeral git worktree at `.story_kit/merge_workspace`, does the squash merge + commit, then runs quality gates. But it **never installs frontend dependencies**, so every gate fails and master never moves forward.
+
+## Root Cause
+
+The merge worktree is created via `git worktree add` (line 2383-2396) which is just a git checkout — no `node_modules/`, no `frontend/dist/`. The quality gates (`run_merge_quality_gates` at line 2773) then run:
+
+1. **`cargo clippy`** (line 2781) — FAILS because RustEmbed requires `frontend/dist/` to exist at compile time
+2. **`pnpm build`** (line 2818) — FAILS because no `node_modules/` (never ran `pnpm install`)
+3. **`pnpm test`** (line 2841) — FAILS for the same reason
+
+Result: `gates_passed: false`, worktree cleaned up, master unchanged. Every single merge attempt fails.
+
+## The Fix
+
+Add frontend dependency setup between worktree creation (line 2396) and quality gates (line 2513). After the squash merge commit succeeds, but before gates run:
+
+1. `mkdir -p frontend/dist` — minimum for cargo clippy to not fail on RustEmbed
+2. Run `pnpm install` in the worktree's `frontend/` directory
+3. The existing `pnpm build` gate (line 2818) will then populate `frontend/dist/` properly
+
+The dependency install step should happen right after the commit (line 2511) and before the quality gates comment at line 2513. Add it as a clearly labeled section:
+
+```
+// ── Install frontend dependencies for quality gates ──────────
+```
+
+If `pnpm install` fails, treat it the same as a gate failure: log output, cleanup, return `success: false`.
+
+## Key File
+
+- `server/src/agents.rs` line 2383-2396: worktree creation (no deps installed)
+- `server/src/agents.rs` line 2513-2549: quality gates (need deps to pass)
+- `server/src/agents.rs` line 2773: `run_merge_quality_gates()` — runs cargo clippy, pnpm build, pnpm test
+
+## Acceptance Criteria
+
+- [ ] After merge worktree is created and commit is made, `pnpm install` runs in the worktree's `frontend/` directory
+- [ ] `mkdir -p frontend/dist` is created before cargo clippy runs (as a fallback in case pnpm install succeeds but build hasn't run yet)
+- [ ] If `pnpm install` fails, merge is aborted cleanly with diagnostic output
+- [ ] Quality gates (cargo clippy, pnpm build, pnpm test) pass in the merge worktree for a normal merge with no conflicts