## Context
The Dispatch-to-Agent button in the right-panel (previous commit) calls
two endpoints that did not yet exist server-side:
- `POST /api/agent-dispatch` — resolve the bead via the same Dolt pool
the existing `/api/beads/read` route uses, build a prompt from it, and
forward to `claude-agent-service`'s `/execute` endpoint with a bearer
token. This is the server-side trust boundary: the bearer token lives
in env (never in the browser), and the bead is re-read from Dolt
(never trusted from the client payload) so a malicious client cannot
inject a prompt.
- `GET /api/agent-status` — proxy `claude-agent-service`'s `/health`
endpoint (which already returns `{status, busy}`), with a 2 s in-
memory cache so 5 s UI polls across multiple open tabs don't hammer
the service.
The claude-agent-service serialises jobs behind an `asyncio.Lock` — a
second `/execute` while one is running returns HTTP 409 "Agent is busy".
We surface that 409 through to the browser unchanged so the UI can show
the right toast/status line without re-mapping status codes.
```
client ──► /api/agent-dispatch ──► claude-agent-service /execute
│ (asyncio.Lock guards)
└─► reads bead from Dolt pool (same path as /api/beads/read)
└─► buildDispatchPrompt(bead)
└─► POST {prompt, agent, budget, timeout} + Bearer token
client ──► /api/agent-status (2s cache) ──► /health ──► {busy: bool}
```
## This change
### `src/app/api/agent-dispatch/route.ts`
- `POST {taskId: string}` handler.
- Validates JSON body and non-empty taskId (→ 400).
- Early 500 if `CLAUDE_AGENT_SERVICE_URL` or `CLAUDE_AGENT_BEARER_TOKEN`
is missing — fail fast, fail loud.
- Resolves the bead via `readIssuesFromDisk({preferBd: true})`, which
uses the existing Dolt client (and falls back to `issues.jsonl`).
Filtering by id after is acceptable at BeadBoard's scale (~hundreds
of beads) and avoids introducing a new single-bead query path.
- 400 when the bead is missing, or when `acceptance_criteria?.trim()` is
empty — defense in depth alongside the UI disable. The button should
already hide in these cases, but a curl'd POST must still be rejected.
- Forwards to `${CLAUDE_AGENT_SERVICE_URL}/execute` with agent
`beads-task-runner`, max_budget_usd 5, timeout_seconds 900 (matches
the values in the task spec).
- Passes through 409 verbatim. Other upstream errors collapse to 502.
### `src/app/api/agent-status/route.ts`
- `GET` handler, module-level snapshot cache with 2 s TTL to avoid
hammering `/health`.
- In-flight de-dup: a single pending `fetchRemoteStatus()` is shared
across concurrent requests so we only hit the upstream once per
window even under bursty load.
- When `CLAUDE_AGENT_SERVICE_URL` is unset, returns `{busy: false}` and
skips the fetch entirely — this is how the dev server boots before
the service env is configured.
- HTTP 503 from upstream is interpreted as `busy: true` (future-proofing
in case the service swaps 409 for 503 on overload).
- Any network error degrades gracefully to `{busy: false}` — the 409
path on `/api/agent-dispatch` is the authoritative gate.
### Test coverage
- `tests/api/agent-dispatch-route.test.ts` (3 cases): invalid JSON body,
missing taskId, missing env returns 500.
- `tests/api/agent-status-route.test.ts` (3 cases): unset service URL
returns `{busy: false}` without a fetch, `/health busy:true` proxies
through, HTTP 503 maps to busy=true. Uses a `globalThis.fetch` stub
and cache-busting query params on dynamic import so each case starts
from a fresh module snapshot.
## What is NOT in this change
- End-to-end happy-path coverage (bead loads, fetch returns 200, route
yields job_id) would require mocking `readIssuesFromDisk` — that's a
bigger refactor than this commit warrants. Live integration happens
once the pipeline is wired.
- No retry/backoff on upstream failures. 502 passes through; the client
decides whether to retry.
- No auth on the routes themselves — they inherit the Next.js app's
session model (same as all other `/api/*` routes today).
## Test Plan
### Automated
```
$ node --import tsx --test tests/api/agent-dispatch-route.test.ts \
tests/api/agent-status-route.test.ts
# tests 6 pass 6 fail 0 duration_ms 1560
```
All six route cases pass. Typecheck output shows only the pre-existing
`OrchestratorChatMessage` gap in `left-panel.tsx`. Lint output is
unchanged from `main` (1 pre-existing `no-require-imports` error in
`src/lib/bb-pi-bootstrap.ts`).
### Manual Verification
1. Export env:
```
export CLAUDE_AGENT_SERVICE_URL=http://claude-agent-service.claude-agent.svc.cluster.local:8080
export CLAUDE_AGENT_BEARER_TOKEN=$(vault kv get -field=api_bearer_token secret/claude-agent-service)
```
2. `npm run dev`
3. `curl -s http://localhost:3000/api/agent-status` → `{"busy":false}`
(if the service is reachable; `{"busy":true}` if a job is running).
4. `curl -X POST http://localhost:3000/api/agent-dispatch \
-H 'content-type: application/json' \
-d '{"taskId":"beadboard-xyz"}'`
- 400 if bead does not exist or lacks acceptance criteria.
- 200 `{"job_id":"..."}` on success.
- 409 `{"error":"Agent is busy"}` when an agent is already running.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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