feat(chat): unify session gateway with stable IDs and a single WS protocol

The frontend previously juggled placeholder IDs, provider-native IDs, and session_created handoffs, which caused race conditions and provider-specific branching. This introduces app-allocated session IDs, a chat run registry with event replay, delta sidebar updates, and one kind-based websocket contract so the UI can treat every provider the same while JSONL remains the source of truth.

server/modules/database/tests/sessions-provider-mapping.test.ts

@@ -0,0 +1,108 @@
+import assert from 'node:assert/strict';
+import { mkdtemp, rm } from 'node:fs/promises';
+import { tmpdir } from 'node:os';
+import path from 'node:path';
+import test from 'node:test';
+
+import { closeConnection } from '@/modules/database/connection.js';
+import { initializeDatabase } from '@/modules/database/init-db.js';
+import { sessionsDb } from '@/modules/database/repositories/sessions.db.js';
+
+async function withIsolatedDatabase(runTest: () => void | Promise<void>): Promise<void> {
+  const previousDatabasePath = process.env.DATABASE_PATH;
+  const tempDirectory = await mkdtemp(path.join(tmpdir(), 'sessions-mapping-'));
+  const databasePath = path.join(tempDirectory, 'auth.db');
+
+  closeConnection();
+  process.env.DATABASE_PATH = databasePath;
+  await initializeDatabase();
+
+  try {
+    await runTest();
+  } finally {
+    closeConnection();
+    if (previousDatabasePath === undefined) {
+      delete process.env.DATABASE_PATH;
+    } else {
+      process.env.DATABASE_PATH = previousDatabasePath;
+    }
+    await rm(tempDirectory, { recursive: true, force: true });
+  }
+}
+
+test('disk-discovered sessions are keyed by the provider id for both columns', async () => {
+  await withIsolatedDatabase(() => {
+    sessionsDb.createSession('provider-abc', 'claude', '/workspace/demo', 'From Disk');
+
+    const row = sessionsDb.getSessionById('provider-abc');
+    assert.equal(row?.session_id, 'provider-abc');
+    assert.equal(row?.provider_session_id, 'provider-abc');
+
+    const byProviderId = sessionsDb.getSessionByProviderSessionId('provider-abc');
+    assert.equal(byProviderId?.session_id, 'provider-abc');
+  });
+});
+
+test('app sessions get the provider id assigned without creating a duplicate row', async () => {
+  await withIsolatedDatabase(() => {
+    sessionsDb.createAppSession('app-id-1', 'claude', '/workspace/demo');
+    sessionsDb.assignProviderSessionId('app-id-1', 'provider-xyz');
+
+    // A later synchronizer pass that discovers the transcript on disk must
+    // update the app row in place instead of inserting a provider-keyed row.
+    const returnedId = sessionsDb.createSession(
+      'provider-xyz',
+      'claude',
+      '/workspace/demo',
+      'Synced Name',
+      undefined,
+      undefined,
+      '/fake/path/provider-xyz.jsonl',
+    );
+
+    assert.equal(returnedId, 'app-id-1');
+    assert.equal(sessionsDb.getAllSessions().length, 1);
+
+    const row = sessionsDb.getSessionById('app-id-1');
+    assert.equal(row?.provider_session_id, 'provider-xyz');
+    assert.equal(row?.jsonl_path, '/fake/path/provider-xyz.jsonl');
+  });
+});
+
+test('assignProviderSessionId merges a watcher-created duplicate into the app row', async () => {
+  await withIsolatedDatabase(() => {
+    sessionsDb.createAppSession('app-id-2', 'codex', '/workspace/demo');
+
+    // Simulate the race: the filesystem watcher indexed the provider
+    // transcript before the runtime announced its session id to the gateway.
+    sessionsDb.createSession(
+      'provider-race',
+      'codex',
+      '/workspace/demo',
+      'Watcher Name',
+      undefined,
+      undefined,
+      '/fake/provider-race.jsonl',
+    );
+    assert.equal(sessionsDb.getAllSessions().length, 2);
+
+    sessionsDb.assignProviderSessionId('app-id-2', 'provider-race');
+
+    const rows = sessionsDb.getAllSessions();
+    assert.equal(rows.length, 1);
+    assert.equal(rows[0]?.session_id, 'app-id-2');
+    assert.equal(rows[0]?.provider_session_id, 'provider-race');
+    // Transcript path and name from the duplicate are adopted.
+    assert.equal(rows[0]?.jsonl_path, '/fake/provider-race.jsonl');
+    assert.equal(rows[0]?.custom_name, 'Watcher Name');
+  });
+});
+
+test('legacy provider-keyed rows stay resolvable through both lookups', async () => {
+  await withIsolatedDatabase(() => {
+    sessionsDb.createSession('legacy-1', 'gemini', '/workspace/demo');
+
+    assert.equal(sessionsDb.getSessionById('legacy-1')?.provider, 'gemini');
+    assert.equal(sessionsDb.getSessionByProviderSessionId('legacy-1')?.session_id, 'legacy-1');
+  });
+});