feat(web): add ensureTaskLogStream and taskLogStreams for task card log streaming (task 6)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 77 insertions, 0 deletions

diff --git a/web/test/tasks-board.test.mjs b/web/test/tasks-board.test.mjs
index 1e35e18..2e1f276 100644
--- a/web/test/tasks-board.test.mjs
+++ b/web/test/tasks-board.test.mjs
@@ -249,3 +249,80 @@ describe('cardContentSignature', () => {
     assert.notEqual(cardContentSignature(cardA), cardContentSignature(cardB));
   });
 });
+
+// ── ensureTaskLogStream: stream lifecycle (reuse vs. reopen vs. no-op) ─────
+
+import { ensureTaskLogStream, taskLogStreams } from '../app.js';
+
+function makeFakeEventSource() {
+  const instances = [];
+  function FakeEventSource(url) {
+    this.url = url;
+    this.closed = false;
+    this._listeners = {};
+    instances.push(this);
+  }
+  FakeEventSource.prototype.close = function () { this.closed = true; };
+  FakeEventSource.prototype.addEventListener = function (type, fn) { this._listeners[type] = fn; };
+  Object.defineProperty(FakeEventSource.prototype, 'onmessage', { writable: true, value: null });
+  Object.defineProperty(FakeEventSource.prototype, 'onerror', { writable: true, value: null });
+  FakeEventSource.instances = instances;
+  return FakeEventSource;
+}
+
+function makeFakeLogArea() {
+  return {
+    children: [],
+    appendChild(c) { this.children.push(c); },
+    removeChild(c) { this.children = this.children.filter(x => x !== c); },
+    get childElementCount() { return this.children.length; },
+    get firstElementChild() { return this.children[0]; },
+    get innerHTML() { return ''; },
+    set innerHTML(_) { this.children = []; }, // mirrors real DOM: assigning innerHTML clears children
+    scrollTop: 0, scrollHeight: 0, clientHeight: 0, addEventListener() {},
+  };
+}
+
+describe('ensureTaskLogStream', () => {
+  it('does nothing when the task has no executions yet (Queue)', async () => {
+    const fetchFn = async () => ({ ok: true, json: async () => [] });
+    const FakeES = makeFakeEventSource();
+    const logArea = makeFakeLogArea();
+    await ensureTaskLogStream('task-queue-1', logArea, { fetchFn, EventSourceImpl: FakeES, apiBase: '' });
+    assert.equal(FakeES.instances.length, 0);
+  });
+
+  it('opens a stream for a task with an execution', async () => {
+    const fetchFn = async () => ({ ok: true, json: async () => [{ id: 'exec-1' }] });
+    const FakeES = makeFakeEventSource();
+    const logArea = makeFakeLogArea();
+    await ensureTaskLogStream('task-1', logArea, { fetchFn, EventSourceImpl: FakeES, apiBase: '' });
+    assert.equal(FakeES.instances.length, 1);
+    assert.match(FakeES.instances[0].url, /\/api\/executions\/exec-1\/logs\/stream/);
+    assert.equal(taskLogStreams['task-1'].execId, 'exec-1');
+  });
+
+  it('does not reopen a stream already attached to the same execution', async () => {
+    const fetchFn = async () => ({ ok: true, json: async () => [{ id: 'exec-2' }] });
+    const FakeES = makeFakeEventSource();
+    const logArea = makeFakeLogArea();
+    await ensureTaskLogStream('task-2', logArea, { fetchFn, EventSourceImpl: FakeES, apiBase: '' });
+    await ensureTaskLogStream('task-2', logArea, { fetchFn, EventSourceImpl: FakeES, apiBase: '' });
+    assert.equal(FakeES.instances.length, 1, 'should not open a second stream for the same execution');
+  });
+
+  it('closes the old stream and opens a new one when the execution id changes', async () => {
+    let call = 0;
+    const fetchFn = async () => {
+      call++;
+      return { ok: true, json: async () => [{ id: call === 1 ? 'exec-a' : 'exec-b' }] };
+    };
+    const FakeES = makeFakeEventSource();
+    const logArea = makeFakeLogArea();
+    await ensureTaskLogStream('task-3', logArea, { fetchFn, EventSourceImpl: FakeES, apiBase: '' });
+    await ensureTaskLogStream('task-3', logArea, { fetchFn, EventSourceImpl: FakeES, apiBase: '' });
+    assert.equal(FakeES.instances.length, 2);
+    assert.ok(FakeES.instances[0].closed, 'old stream should be closed');
+    assert.equal(taskLogStreams['task-3'].execId, 'exec-b');
+  });
+});