feat: persist agent assignment before task execution

- Add UpdateTaskAgent to Store interface and DB implementation
- Call UpdateTaskAgent in Pool.execute to persist assigned agent/model
  to database before the runner starts
- Update runTask in app.js to pass selected agent as query param

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

1 files changed, 8 insertions, 3 deletions

diff --git a/web/app.js b/web/app.js
index 6bcdf57..bca41fa 100644
--- a/web/app.js
+++ b/web/app.js
@@ -456,8 +456,11 @@ function renderAllPanel(tasks) {
 
 // ── Run action ────────────────────────────────────────────────────────────────
 
-async function runTask(taskId) {
-  const res = await fetch(`${API_BASE}/api/tasks/${taskId}/run`, { method: 'POST' });
+async function runTask(taskId, agent) {
+  const url = agent && agent !== 'auto'
+    ? `${API_BASE}/api/tasks/${taskId}/run?agent=${agent}`
+    : `${API_BASE}/api/tasks/${taskId}/run`;
+  const res = await fetch(url, { method: 'POST' });
   if (!res.ok) {
     let msg = `HTTP ${res.status}`;
     try { const body = await res.json(); msg = body.error || body.message || msg; } catch {}
@@ -467,6 +470,8 @@ async function runTask(taskId) {
 }
 
 async function handleRun(taskId, btn, footer) {
+  const agentSelector = document.getElementById('select-agent');
+  const agent = agentSelector ? agentSelector.value : 'auto';
   btn.disabled = true;
   btn.textContent = 'Queuing…';
 
@@ -475,7 +480,7 @@ async function handleRun(taskId, btn, footer) {
   if (prev) prev.remove();
 
   try {
-    await runTask(taskId);
+    await runTask(taskId, agent);
     // Refresh active panel so state flips to QUEUED
     await poll();
   } catch (err) {