Task #3: MVP API — payment-gated jobs + demo endpoint

OpenAPI spec (lib/api-spec/openapi.yaml)
- Added POST /jobs, GET /jobs/{id}, GET /demo endpoints
- Added schemas: CreateJobRequest, CreateJobResponse, JobStatusResponse,
  InvoiceInfo, JobState, DemoResponse, ErrorResponse
- Ran codegen: generated CreateJobBody, GetJobResponse, RunDemoQueryParams etc.

Jobs router (artifacts/api-server/src/routes/jobs.ts)
- POST /jobs: validates body, creates LNbits eval invoice, inserts job +
  invoice in a DB transaction, returns { jobId, evalInvoice }
- GET /jobs/🆔 fetches job, calls advanceJob() helper, returns state-
  appropriate payload (eval/work invoice, reason, result, errorMessage)
- advanceJob() state machine:
  - awaiting_eval_payment: checks LNbits, atomically marks paid + advances
    state via optimistic WHERE state='awaiting_eval_payment'; runs
    AgentService.evaluateRequest, branches to awaiting_work_payment or rejected
  - awaiting_work_payment: same pattern for work invoice, runs
    AgentService.executeWork, advances to complete
  - Any agent/LNbits error transitions job to failed

Demo router (artifacts/api-server/src/routes/demo.ts)
- GET /demo?request=...: in-memory rate limiter (5 req/hour per IP)
- Explicit guard for missing request param (coerce.string() workaround)
- Calls AgentService.executeWork directly, returns { result }

Dev router (artifacts/api-server/src/routes/dev.ts)
- POST /dev/stub/pay/:paymentHash: marks stub invoice paid in-memory
- Only mounted when NODE_ENV !== 'production'

Route index updated to mount all three routers

replit.md: documented full curl flow with all 6 steps, demo endpoint,
and dev stub-pay trigger

End-to-end verified with curl:
- Full flow: create → eval pay → evaluating → work pay → executing → complete
- Error cases: 400 on missing body/param, 404 on unknown job

lib/api-zod/src/generated/api.ts

@@ -14,3 +14,60 @@ import * as zod from "zod";
 export const HealthCheckResponse = zod.object({
   status: zod.string(),
 });
+
+/**
+ * Accepts a request, creates a job row, and issues an eval fee Lightning invoice.
+ * @summary Create a new agent job
+ */
+
+export const CreateJobBody = zod.object({
+  request: zod.string().min(1),
+});
+
+/**
+ * Returns current job state. Automatically advances the state machine when a pending invoice is found to be paid.
+ * @summary Get job status
+ */
+export const GetJobParams = zod.object({
+  id: zod.coerce.string(),
+});
+
+export const GetJobResponse = zod.object({
+  jobId: zod.string(),
+  state: zod.enum([
+    "awaiting_eval_payment",
+    "evaluating",
+    "rejected",
+    "awaiting_work_payment",
+    "executing",
+    "complete",
+    "failed",
+  ]),
+  evalInvoice: zod
+    .object({
+      paymentRequest: zod.string(),
+      amountSats: zod.number(),
+    })
+    .optional(),
+  workInvoice: zod
+    .object({
+      paymentRequest: zod.string(),
+      amountSats: zod.number(),
+    })
+    .optional(),
+  reason: zod.string().optional(),
+  result: zod.string().optional(),
+  errorMessage: zod.string().optional(),
+});
+
+/**
+ * Runs the agent without payment. Limited to 5 requests per IP per hour.
+ * @summary Free demo (rate-limited)
+ */
+export const RunDemoQueryParams = zod.object({
+  request: zod.coerce.string(),
+});
+
+export const RunDemoResponse = zod.object({
+  result: zod.string(),
+});