PR D: typed + signed event bus + events table + SSE (arch step 5) (#8)

orchestrator/src/db/migrations/003_events.ts

@@ -0,0 +1,43 @@
+import { query } from "../postgres";
+
+/**
+ * Migration 003 — append-only events journal (arch §4.5, §5.5, §7).
+ *
+ * The `events` table is the system-of-record for normalised workflow
+ * events (arch §7.2: `transaction.created`, `instrument.ready`,
+ * `payment.settled`, `transaction.committed`, …). It is:
+ *
+ *   - append-only (no UPDATE / DELETE)
+ *   - signed (HMAC of (plan_id, type, payload_hash, prev_hash))
+ *   - hash-chained via prev_hash for tamper-evident forensic replay
+ *   - indexed by plan_id so the SSE endpoint can stream efficiently
+ */
+export async function up() {
+  await query(
+    `CREATE TABLE IF NOT EXISTS events (
+       id           UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+       plan_id      UUID NOT NULL REFERENCES plans(plan_id) ON DELETE CASCADE,
+       type         VARCHAR(128) NOT NULL,
+       actor        VARCHAR(255),
+       payload      JSONB NOT NULL DEFAULT '{}'::jsonb,
+       payload_hash CHAR(64) NOT NULL,
+       prev_hash    CHAR(64),
+       signature    CHAR(64) NOT NULL,
+       created_at   TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP
+     )`,
+  );
+
+  await query(
+    `CREATE INDEX IF NOT EXISTS idx_events_plan_id_created
+       ON events(plan_id, created_at)`,
+  );
+
+  await query(
+    `CREATE INDEX IF NOT EXISTS idx_events_type
+       ON events(type)`,
+  );
+}
+
+export async function down() {
+  await query("DROP TABLE IF EXISTS events CASCADE");
+}

orchestrator/src/db/migrations/index.ts

@@ -1,5 +1,6 @@
 import { up as up001 } from "./001_initial_schema";
 import { up as up002 } from "./002_transaction_state";
+import { up as up003 } from "./003_events";
 
 /**
  * Run all migrations
@@ -8,6 +9,7 @@ export async function runMigration() {
   try {
     await up001();
     await up002();
+    await up003();
     console.log("All migrations completed");
   } catch (error) {
     console.error("Migration failed:", error);