feat(api): conversations + messages routes

Add conversations CRUD-lite (list, create, get, PATCH status, PATCH
summary which flips status to summarized) and conversation-scoped
messages (append, list ordered by created_at).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

lib/api/routes/conversations.js

@@ -0,0 +1,65 @@
+import { Router } from 'express';
+import { z } from 'zod';
+import * as repo from '../../db/repos/conversations.js';
+import { validate } from '../validate.js';
+import { parsePagination } from '../pagination.js';
+import { NotFoundError, asyncWrap } from '../errors.js';
+
+const STATUSES = ['open', 'summarized', 'archived'];
+
+const createSchema = z.object({
+  title: z.string().nullable().optional(),
+  agent_id: z.string().uuid().nullable().optional(),
+  participants: z.array(z.string()).optional(),
+  metadata: z.record(z.string(), z.any()).optional()
+});
+
+const statusSchema = z.object({ status: z.enum(STATUSES) });
+const summarySchema = z.object({ summary: z.string().min(1) });
+
+const idParams = z.object({ id: z.string().uuid() });
+
+export const router = Router();
+
+router.get('/',
+  validate({ query: z.object({ limit: z.string().optional(), offset: z.string().optional() }) }),
+  asyncWrap(async (req, res) => {
+    const { limit, offset } = parsePagination(req);
+    res.json(await repo.list({ limit, offset }));
+  })
+);
+
+router.post('/',
+  validate({ body: createSchema }),
+  asyncWrap(async (req, res) => {
+    const row = await repo.create(req.body, req.actor);
+    res.status(201).json(row);
+  })
+);
+
+router.get('/:id',
+  validate({ params: idParams }),
+  asyncWrap(async (req, res) => {
+    const row = await repo.getById(req.params.id);
+    if (!row) throw new NotFoundError('conversation not found');
+    res.json(row);
+  })
+);
+
+router.patch('/:id/status',
+  validate({ params: idParams, body: statusSchema }),
+  asyncWrap(async (req, res) => {
+    const existing = await repo.getById(req.params.id);
+    if (!existing) throw new NotFoundError('conversation not found');
+    res.json(await repo.setStatus(req.params.id, req.body.status, req.actor));
+  })
+);
+
+router.patch('/:id/summary',
+  validate({ params: idParams, body: summarySchema }),
+  asyncWrap(async (req, res) => {
+    const existing = await repo.getById(req.params.id);
+    if (!existing) throw new NotFoundError('conversation not found');
+    res.json(await repo.setSummary(req.params.id, req.body.summary));
+  })
+);