fix(web): preserve running state for queued prompts

tests/web/app-render.test.ts

@@ -867,6 +867,58 @@ test("app.js settles an admitted prompt that Pi handles without an agent turn",
   assert.equal((app.state.terminalPromptIds as Set<string>).size, 32);
 });
 
+test("app.js keeps an active agent running when a handled prompt settles", async () => {
+  const app = await renderApp();
+  vm.runInContext(
+    'applyRuntimeEvent({sequence: 2, type: "agent_start", detail: {sessionId: "s1"}}); applyRuntimeEvent({sequence: 3, type: "prompt_settled", detail: {sessionId: "s1", commandId: "handled"}}); applyRuntimeEvent({sequence: 4, type: "prompt_accepted", detail: {sessionId: "s1", commandId: "handled"}})',
+    app.context as vm.Context,
+  );
+  assert.equal(app.state.liveRunning, true);
+  assert.equal(app.state.livePhase, "running");
+
+  vm.runInContext(
+    'applyRuntimeEvent({sequence: 5, type: "agent_settled", detail: {sessionId: "s1"}})',
+    app.context as vm.Context,
+  );
+  assert.equal(app.state.liveRunning, false);
+  assert.equal(app.state.livePhase, "idle");
+});
+
+test("app.js keeps an active agent running when a queued prompt is accepted", async () => {
+  const app = await renderApp();
+  vm.runInContext(
+    'applyRuntimeEvent({sequence: 2, type: "agent_start", detail: {sessionId: "s1"}}); applyRuntimeEvent({sequence: 3, type: "prompt_accepted", detail: {sessionId: "s1", commandId: "queued"}})',
+    app.context as vm.Context,
+  );
+  assert.equal(app.state.liveRunning, true);
+  assert.equal(app.state.livePhase, "running");
+});
+
+test("app.js keeps an active agent running when its prompt receipt settles late", async () => {
+  const app = await renderApp();
+  const prompt = deferred<ReturnType<typeof response>>();
+  app.context.fetch = async (url: unknown) => {
+    if (String(url) === "/api/prompt") return prompt.promise;
+    if (String(url).startsWith("/api/snapshot")) return response(SNAPSHOT);
+    throw new Error(`unexpected request: ${String(url)}`);
+  };
+  const input = app.elements.get("prompt-input");
+  assert.ok(input);
+  input.value = "late receipt";
+  const sending = app.sendPrompt();
+  await new Promise((resolve) => setTimeout(resolve, 0));
+
+  vm.runInContext(
+    'applyRuntimeEvent({sequence: 2, type: "agent_start", detail: {sessionId: "s1"}}); applyRuntimeEvent({sequence: 3, type: "prompt_settled", detail: {sessionId: "s1", commandId: "late"}})',
+    app.context as vm.Context,
+  );
+  prompt.resolve(response({ id: "late", accepted: true }));
+  await sending;
+
+  assert.equal(app.state.liveRunning, true);
+  assert.equal(app.state.livePhase, "running");
+});
+
 test("app.js scopes model selection to its session epoch", async () => {
   const app = await renderApp();
   const model = deferred<ReturnType<typeof response>>();

web/ui/app.js

@@ -214,6 +214,18 @@ function compactSummary(value, limit = 96) {
   return text.length > limit ? `${text.slice(0, limit - 1)}…` : text;
 }
 
+function applyPromptAcceptedState(alreadySettled) {
+  if (alreadySettled) {
+    if (state.livePhase !== "running") {
+      state.liveRunning = false;
+      state.livePhase = "idle";
+    }
+    return;
+  }
+  state.liveRunning = true;
+  if (state.livePhase !== "running") state.livePhase = "preparing";
+}
+
 function relativeTime(value) {
   const elapsed = Date.now() - new Date(value).getTime();
   if (elapsed < 60_000) return "now";
@@ -747,8 +759,7 @@ async function sendPrompt() {
     });
     if (epoch !== state.sessionEpoch || state.promptAdmissionToken !== admissionToken) return;
     const alreadySettled = state.terminalPromptIds.has(receipt.id);
-    state.liveRunning = !alreadySettled;
-    state.livePhase = alreadySettled ? "idle" : "preparing";
+    applyPromptAcceptedState(alreadySettled);
     $("prompt-input").value = "";
     resizePrompt();
     $("composer-hint").textContent = t("acceptedHint");
@@ -1066,21 +1077,27 @@ function applyRuntimeEvent(event) {
     scheduleSnapshotRefresh();
   } else if (event.type === "prompt_accepted") {
     const alreadySettled = state.terminalPromptIds.has(event.detail?.commandId);
-    state.liveRunning = !alreadySettled;
-    state.livePhase = alreadySettled ? "idle" : "preparing";
+    applyPromptAcceptedState(alreadySettled);
     state.liveRetry = null;
     renderConversation();
   } else if (event.type === "agent_start") {
     state.liveRunning = true;
     state.livePhase = "running";
     state.liveRetry = null;
     renderConversation();
-  } else if (event.type === "agent_settled" || event.type === "prompt_settled") {
-    if (event.type === "prompt_settled") rememberTerminalPrompt(event.detail?.commandId);
+  } else if (event.type === "agent_settled") {
     state.liveRunning = false;
     state.livePhase = "idle";
     state.liveRetry = null;
     renderConversation();
+  } else if (event.type === "prompt_settled") {
+    rememberTerminalPrompt(event.detail?.commandId);
+    if (state.livePhase !== "running") {
+      state.liveRunning = false;
+      state.livePhase = "idle";
+      state.liveRetry = null;
+    }
+    renderConversation();
   } else if (event.detail?.message) {
     if (event.detail.message.role === "user") {
       state.liveMessages = state.liveMessages.filter(