fix: restore model activity reasoning stream

frontend/src/api/types.ts

@@ -58,6 +58,7 @@ export interface UiResponse {
 export type StreamEvent =
   | { type: "ui_request"; ui_request: WidgetDescriptor }
   | { type: "text_delta"; text: string }
+  | { type: "activity_delta"; text: string }
   | { type: "info"; level?: "info" | "warning" | "error"; text: string }
   | { type: "system_event"; event: string; [k: string]: unknown };
 

frontend/src/shell/ModelActivityPanel.test.tsx

@@ -6,14 +6,22 @@ import { ModelActivityPanel } from "./ModelActivityPanel";
 
 beforeEach(() => useSessionStore.getState().resetSession());
 
-test("renders the streamed model transcript", () => {
-  useSessionStore.getState().applyEvent({ type: "text_delta", text: "Promoting table dim_patient." });
+test("renders the streamed model activity", () => {
+  useSessionStore.getState().applyEvent({ type: "activity_delta", text: "Promoting table dim_patient." });
   render(<ModelActivityPanel onClose={vi.fn()} />);
   expect(screen.getByText(/Promoting table dim_patient/)).toBeInTheDocument();
 });
 
+test("does not treat final assistant text as model reasoning", () => {
+  useSessionStore.getState().applyEvent({ type: "text_delta", text: "Final answer" });
+  render(<ModelActivityPanel onClose={vi.fn()} />);
+
+  expect(screen.queryByText("Final answer")).not.toBeInTheDocument();
+  expect(screen.getByText("No activity yet.")).toBeInTheDocument();
+});
+
 test("renders markdown emphasis instead of literal asterisks", () => {
-  useSessionStore.getState().applyEvent({ type: "text_delta", text: "Chiarimento su **fibrillazione atriale**." });
+  useSessionStore.getState().applyEvent({ type: "activity_delta", text: "Chiarimento su **fibrillazione atriale**." });
   render(<ModelActivityPanel onClose={vi.fn()} />);
   expect(screen.getByText("fibrillazione atriale").tagName).toBe("STRONG");
 });
@@ -28,7 +36,7 @@ test("close button calls onClose", async () => {
 const EIGHT = ["para-01", "para-02", "para-03", "para-04", "para-05", "para-06", "para-07", "para-08"].join("\n\n");
 
 test("collapsed shows only the last 5 paragraphs of the model-stream tail", () => {
-  useSessionStore.getState().applyEvent({ type: "text_delta", text: EIGHT });
+  useSessionStore.getState().applyEvent({ type: "activity_delta", text: EIGHT });
   render(<ModelActivityPanel onClose={vi.fn()} />);
   expect(screen.getByText("para-08")).toBeInTheDocument();
   expect(screen.getByText("para-04")).toBeInTheDocument();
@@ -37,7 +45,7 @@ test("collapsed shows only the last 5 paragraphs of the model-stream tail", () =
 });
 
 test("expanding reveals the full stream", async () => {
-  useSessionStore.getState().applyEvent({ type: "text_delta", text: EIGHT });
+  useSessionStore.getState().applyEvent({ type: "activity_delta", text: EIGHT });
   render(<ModelActivityPanel onClose={vi.fn()} />);
   await userEvent.click(screen.getByRole("button", { name: /show more/i }));
   expect(screen.getByText("para-01")).toBeInTheDocument();
@@ -46,7 +54,7 @@ test("expanding reveals the full stream", async () => {
 test("paragraphs stay separated as distinct blocks", () => {
   useSessionStore
     .getState()
-    .applyEvent({ type: "text_delta", text: "Primo paragrafo.\n\nSecondo paragrafo." });
+    .applyEvent({ type: "activity_delta", text: "Primo paragrafo.\n\nSecondo paragrafo." });
   render(<ModelActivityPanel onClose={vi.fn()} />);
   const first = screen.getByText("Primo paragrafo.");
   const second = screen.getByText("Secondo paragrafo.");
@@ -58,7 +66,7 @@ test("paragraphs stay separated as distinct blocks", () => {
 
 test("separates activity updates concatenated after sentence punctuation", () => {
   useSessionStore.getState().applyEvent({
-    type: "text_delta",
+    type: "activity_delta",
     text: "Ambiguità principale risolta.Finestra temporale risolta.Terza ambiguità risolta.",
   });
   render(<ModelActivityPanel onClose={vi.fn()} />);

frontend/src/shell/ModelActivityPanel.tsx

@@ -24,13 +24,13 @@ export function formatModelActivity(text: string): string {
  *  (refreshing as the stream grows); the expand toggle reveals the full stream. Opened
  *  on demand from the rotating activity icon. */
 export function ModelActivityPanel({ onClose }: { onClose: () => void }) {
-  const transcript = useSessionStore((s) => s.transcript);
+  const activity = useSessionStore((s) => s.activity);
   const [expanded, setExpanded] = useState(false);
 
   // Blank lines are markdown's paragraph separator — split on them (not on every "\n",
   // which would also break single soft-wrapped lines apart) so each block below is a
   // real paragraph and the tail cut lands on paragraph boundaries.
-  const paragraphs = transcript
+  const paragraphs = activity
     .map((e) => e.text)
     .join("\n\n")
     .split(/\n{2,}/)

frontend/src/store/sessionStore.test.ts

@@ -15,6 +15,15 @@ test("text_delta accumulates into transcript", () => {
   expect(useSessionStore.getState().transcript.at(-1)?.text).toBe("Analisi");
 });
 
+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().transcript).toEqual([]);
+});
+
 test("info appends to stepMessages", () => {
   useSessionStore.getState().applyEvent({ type: "info", level: "warning", text: "attenzione" });
   expect(useSessionStore.getState().stepMessages.at(-1)).toEqual({ level: "warning", text: "attenzione" });
@@ -122,4 +131,5 @@ test("resetSession clears lastUserEntry and stepMessages", () => {
   st.resetSession();
   expect(useSessionStore.getState().lastUserEntry).toBeNull();
   expect(useSessionStore.getState().stepMessages).toEqual([]);
+  expect(useSessionStore.getState().activity).toEqual([]);
 });

frontend/src/store/sessionStore.ts

@@ -9,6 +9,7 @@ interface Entry {
 interface SessionState {
   pendingWidget: WidgetDescriptor | null;
   transcript: Entry[];
+  activity: Entry[];
   toasts: { level: string; text: string }[];
   stepMessages: { level: string; text: string }[];
   lastUserEntry: { kind: "input" | "choice"; text: string } | null;
@@ -31,6 +32,7 @@ interface SessionState {
 const empty = {
   pendingWidget: null,
   transcript: [] as Entry[],
+  activity: [] as Entry[],
   toasts: [] as { level: string; text: string }[],
   stepMessages: [] as { level: string; text: string }[],
   lastUserEntry: null as { kind: "input" | "choice"; text: string } | null,
@@ -63,6 +65,13 @@ export const useSessionStore = create<SessionState>((set) => ({
         // Streamed text means the turn is alive (also covers reattaching mid-turn).
         return { transcript: t, agentActive: true };
       }
+      if (e.type === "activity_delta") {
+        const activity = [...st.activity];
+        const last = activity.at(-1);
+        if (last) activity[activity.length - 1] = { role: "assistant", text: last.text + e.text };
+        else activity.push({ role: "assistant", text: e.text });
+        return { activity, agentActive: true };
+      }
       if (e.type === "info") {
         const stepMessages = [...st.stepMessages, { level: e.level ?? "info", text: e.text }];
         // An error during the active phase marks that phase red until the next gate.