fix: recover ACP parser after bracket logs

apps/daemon/src/acp.ts

@@ -289,6 +289,7 @@ function currentModelFromSessionResult(result: JsonObject): string | null {
 export function createJsonLineStream(onMessage: (message: unknown, rawLine: string) => void) {
   let buffer = '';
   let pendingJson = '';
+  let pendingJsonLineCount = 0;
 
   const emit = (candidate: string): boolean => {
     try {
@@ -301,18 +302,32 @@ export function createJsonLineStream(onMessage: (message: unknown, rawLine: stri
 
   const startPendingJson = (line: string) => {
     pendingJson = line;
+    pendingJsonLineCount = 1;
   };
 
   const handleLine = (line: string) => {
     const trimmed = line.trim();
     if (!trimmed) return;
     if (pendingJson) {
+      if ((trimmed.startsWith('{') || trimmed.startsWith('[')) && emit(trimmed)) {
+        pendingJson = '';
+        pendingJsonLineCount = 0;
+        return;
+      }
       const nextCandidate = `${pendingJson}\n${trimmed}`;
       if (emit(nextCandidate)) {
         pendingJson = '';
+        pendingJsonLineCount = 0;
         return;
       }
-      pendingJson = nextCandidate.length <= 128_000 ? nextCandidate : '';
+      pendingJsonLineCount += 1;
+      if (nextCandidate.length <= 128_000 && pendingJsonLineCount <= 256) {
+        pendingJson = nextCandidate;
+        return;
+      }
+      pendingJson = '';
+      pendingJsonLineCount = 0;
+      handleLine(trimmed);
       return;
     }
     if (emit(trimmed)) return;

apps/daemon/tests/acp.test.ts

@@ -408,6 +408,33 @@ test('attachAcpSession accepts pretty-printed ACP startup responses', () => {
   assert.equal(events.some((entry) => entry.event === 'error'), false);
 });
 
+test('attachAcpSession recovers when bracket-prefixed logs precede JSON frames', () => {
+  const child = new FakeAcpChild();
+  const writes: string[] = [];
+  const events: Array<{ event: string; payload: unknown }> = [];
+  child.stdin.on('data', (chunk) => writes.push(String(chunk)));
+
+  attachAcpSession({
+    child: child as never,
+    prompt: 'hello',
+    cwd: '/tmp/od-project',
+    model: null,
+    mcpServers: [],
+    send: (event, payload) => events.push({ event, payload }),
+  });
+
+  child.stdout.write('[vela] starting OpenCode bridge\n');
+  child.stdout.write(`${JSON.stringify({ id: 1, result: {} })}\n`);
+  child.stdout.write('{not json but looks like an object log\n');
+  child.stdout.write(`${JSON.stringify({ id: 2, result: { sessionId: 'session-1' } })}\n`);
+
+  const methods = parseRpcWrites(writes)
+    .map((entry) => entry.method)
+    .filter(Boolean);
+  assert.deepEqual(methods, ['initialize', 'session/new', 'session/prompt']);
+  assert.equal(events.some((entry) => entry.event === 'error'), false);
+});
+
 function parseRpcWrites(writes: string[]): Array<Record<string, unknown>> {
   return writes
     .join('')