feat(frontend): build chronological activity timeline

frontend/src/store/sessionStore.test.ts

@@ -15,18 +15,111 @@ test("text_delta accumulates into transcript", () => {
   expect(useSessionStore.getState().transcript.at(-1)?.text).toBe("Analisi");
 });
 
+test("folds prompt, lifecycle, streams, tool updates, and gates in chronological order", () => {
+  const store = useSessionStore.getState();
+  store.setPhase("F1");
+  store.setLastUserEntry({ kind: "input", text: "How many patients?" });
+  store.applyEvent({ type: "system_event", event: "agent_start" });
+  store.applyEvent({ type: "activity_delta", text: "Inspect " });
+  store.applyEvent({ type: "activity_delta", text: "schema" });
+  store.applyEvent({
+    type: "activity_event",
+    activity: { kind: "tool", toolCallId: "t1", toolName: "bash", status: "running" },
+  });
+  store.applyEvent({ type: "text_delta", text: "I found " });
+  store.applyEvent({ type: "text_delta", text: "the candidates." });
+  store.applyEvent({
+    type: "activity_event",
+    activity: { kind: "tool", toolCallId: "t1", toolName: "bash", status: "completed" },
+  });
+  store.applyEvent({
+    type: "ui_request",
+    ui_request: { id: "g1", widget: "select", phase: "F1_understanding", title: "Confirm intent" },
+  });
+
+  const log = useSessionStore.getState().activityLog;
+  expect(log.map((entry) => entry.kind)).toEqual([
+    "prompt",
+    "lifecycle",
+    "thinking",
+    "tool",
+    "assistant",
+    "gate",
+  ]);
+  expect(log.map((entry) => entry.phase)).toEqual(["F1", "F1", "F1", "F1", "F1", "F1"]);
+  expect(log.find((entry) => entry.kind === "thinking")?.text).toBe("Inspect schema");
+  expect(log.find((entry) => entry.kind === "assistant")?.text).toBe("I found the candidates.");
+  expect(log[3]).toEqual({
+    kind: "tool",
+    phase: "F1",
+    text: "bash",
+    toolCallId: "t1",
+    status: "completed",
+  });
+  expect(log.at(-1)?.text).toBe("Confirm intent");
+});
+
+test("stream chunks coalesce only across adjacent rows of the same kind", () => {
+  const store = useSessionStore.getState();
+  store.applyEvent({ type: "activity_delta", text: "before" });
+  store.applyEvent({ type: "info", level: "info", text: "checkpoint" });
+  store.applyEvent({ type: "activity_delta", text: "after" });
+
+  expect(useSessionStore.getState().activityLog.map((entry) => [entry.kind, entry.text])).toEqual([
+    ["thinking", "before"],
+    ["status", "checkpoint"],
+    ["thinking", "after"],
+  ]);
+});
+
 test("activity_delta accumulates separately from the assistant transcript", () => {
   const s = useSessionStore.getState();
   s.applyEvent({ type: "activity_delta", text: "Valuto " });
   s.applyEvent({ type: "activity_delta", text: "le ambiguità" });
 
-  expect(useSessionStore.getState().activity.at(-1)?.text).toBe("Valuto le ambiguità");
+  expect(useSessionStore.getState().activityLog.at(-1)).toMatchObject({
+    kind: "thinking",
+    text: "Valuto le ambiguità",
+  });
   expect(useSessionStore.getState().transcript).toEqual([]);
 });
 
-test("info appends to stepMessages", () => {
+test("info appends to stepMessages and the chronological status log", () => {
   useSessionStore.getState().applyEvent({ type: "info", level: "warning", text: "attenzione" });
   expect(useSessionStore.getState().stepMessages.at(-1)).toEqual({ level: "warning", text: "attenzione" });
+  expect(useSessionStore.getState().activityLog.at(-1)).toEqual({
+    kind: "status",
+    phase: null,
+    text: "attenzione",
+    level: "warning",
+  });
+});
+
+test("a terminal tool event without a start appends a correlated terminal row", () => {
+  useSessionStore.getState().applyEvent({
+    type: "activity_event",
+    activity: { kind: "tool", toolCallId: "t2", toolName: "read", status: "failed" },
+  });
+
+  expect(useSessionStore.getState().activityLog).toEqual([
+    {
+      kind: "tool",
+      phase: null,
+      text: "read",
+      toolCallId: "t2",
+      status: "failed",
+    },
+  ]);
+});
+
+test("recordLifecycle appends a local lifecycle row using the current phase", () => {
+  const store = useSessionStore.getState();
+  store.setPhase("F4");
+  store.recordLifecycle("Resuming session");
+
+  expect(useSessionStore.getState().activityLog).toEqual([
+    { kind: "lifecycle", phase: "F4", text: "Resuming session" },
+  ]);
 });
 
 test("clearPending removes the widget", () => {
@@ -124,12 +217,12 @@ test("setLastUserEntry records the entry and clears stepMessages", () => {
   expect(useSessionStore.getState().stepMessages).toEqual([]);
 });
 
-test("resetSession clears lastUserEntry and stepMessages", () => {
+test("resetSession clears lastUserEntry, stepMessages, and the complete activity log", () => {
   const st = useSessionStore.getState();
   st.setLastUserEntry({ kind: "choice", text: "promote" });
   st.applyEvent({ type: "info", level: "info", text: "y" });
   st.resetSession();
   expect(useSessionStore.getState().lastUserEntry).toBeNull();
   expect(useSessionStore.getState().stepMessages).toEqual([]);
-  expect(useSessionStore.getState().activity).toEqual([]);
+  expect(useSessionStore.getState().activityLog).toEqual([]);
 });