fix(webui): preserve automation source on streamed replies

webui/src/hooks/useNanobotStream.ts

@@ -37,7 +37,7 @@ interface ActiveAssistantCursor {
 }
 
 type PendingStreamEvent =
-  | { kind: "delta"; text: string; turn: UIMessageTurnFields }
+  | { kind: "delta"; text: string; turn: UIMessageTurnFields; source?: UIMessage["source"] }
   | { kind: "reasoning"; text: string; turn: UIMessageTurnFields };
 
 type UIMessageTurnFields = Pick<UIMessage, "turnId" | "turnPhase" | "turnSeq">;
@@ -778,7 +778,12 @@ export function useNanobotStream(
   }, []);
 
   const appendAnswerChunk = useCallback(
-    (prev: UIMessage[], chunk: string, turn: UIMessageTurnFields = {}): UIMessage[] => {
+    (
+      prev: UIMessage[],
+      chunk: string,
+      turn: UIMessageTurnFields = {},
+      source?: UIMessage["source"],
+    ): UIMessage[] => {
       let next = prev;
       let targetIndex = resolveActiveAssistantIndex(next, turn);
 
@@ -809,6 +814,7 @@ export function useNanobotStream(
         content: target.content + chunk,
         isStreaming: true,
         ...turn,
+        ...(source ? { source } : {}),
       };
       closedAssistantStreamIdsRef.current.delete(merged.id);
       activeAssistantRef.current = { id: merged.id, index: targetIndex };
@@ -823,7 +829,7 @@ export function useNanobotStream(
       let next = prev;
       for (const event of events) {
         if (event.kind === "delta") {
-          next = appendAnswerChunk(next, event.text, event.turn);
+          next = appendAnswerChunk(next, event.text, event.turn, event.source);
         } else {
           if (closeActiveAssistantStream()) clearActivitySegment();
           next = attachReasoningChunk(
@@ -843,6 +849,7 @@ export function useNanobotStream(
     closeAnswerSegment?: boolean;
     finalAnswerText?: string;
     turn?: UIMessageTurnFields;
+    source?: UIMessage["source"];
   }) => {
     if (streamFrameRef.current !== null) {
       window.cancelAnimationFrame(streamFrameRef.current);
@@ -855,7 +862,8 @@ export function useNanobotStream(
     const events = pendingStreamEventsRef.current;
     const finalAnswerText = options?.finalAnswerText;
     const turn = options?.turn ?? {};
-    if (events.length === 0 && finalAnswerText === undefined) {
+    const source = options?.source;
+    if (events.length === 0 && finalAnswerText === undefined && source === undefined) {
       if (options?.closeAnswerSegment) closeActiveAssistantStream();
       return;
     }
@@ -873,6 +881,7 @@ export function useNanobotStream(
             content: finalAnswerText,
             isStreaming: true,
             ...turn,
+            ...(source ? { source } : {}),
           };
           next = replaceMessageAt(next, targetIndex, merged);
           if (!options?.closeAnswerSegment) {
@@ -890,6 +899,7 @@ export function useNanobotStream(
               content: finalAnswerText,
               isStreaming: true,
               ...turn,
+              ...(source ? { source } : {}),
               createdAt: Date.now(),
             },
           ];
@@ -900,6 +910,18 @@ export function useNanobotStream(
             buffer.current = { messageId: id };
           }
         }
+      } else if (source) {
+        const targetIndex =
+          resolveActiveAssistantIndex(next, turn)
+          ?? findStreamingAssistantIndex(next, closedAssistantStreamIdsRef.current, turn);
+        if (targetIndex !== null) {
+          const target = next[targetIndex];
+          next = replaceMessageAt(next, targetIndex, {
+            ...target,
+            ...turn,
+            source,
+          });
+        }
       }
       if (options?.closeAnswerSegment) closeActiveAssistantStream();
       return next;
@@ -1027,6 +1049,7 @@ export function useNanobotStream(
           kind: "delta",
           text: chunk,
           turn: turnFieldsFromEvent(ev, "answer"),
+          source: ev.source,
         });
         schedulePendingStreamFlush();
         return;
@@ -1054,6 +1077,7 @@ export function useNanobotStream(
           closeAnswerSegment: !mergeNext,
           ...(typeof ev.text === "string" ? { finalAnswerText: ev.text } : {}),
           turn,
+          source: ev.source,
         });
         if (suppressStreamUntilTurnEndRef.current) return;
         if (ev.resuming) {

webui/src/lib/types.ts

@@ -1185,12 +1185,16 @@ export type InboundEvent =
       chat_id: string;
       text: string;
       stream_id?: string;
+      /** Lightweight provenance for proactive streamed assistant messages. */
+      source?: UIMessageSource;
     } & InboundTurnMetadata)
   | ({
       event: "stream_end";
       chat_id: string;
       stream_id?: string;
       text?: string;
+      /** Lightweight provenance for proactive streamed assistant messages. */
+      source?: UIMessageSource;
       /** This answer segment ended, but the active agent turn will continue. */
       resuming?: boolean;
       /** The next answer segment continues this same assistant message. */

webui/src/tests/useNanobotStream.test.tsx

@@ -314,6 +314,63 @@ describe("useNanobotStream", () => {
     });
   });
 
+  it("preserves proactive automation source metadata on streamed assistant messages", () => {
+    const fake = fakeClient();
+    const { result } = renderHook(() => useNanobotStream("chat-cron-stream", EMPTY_MESSAGES), {
+      wrapper: wrap(fake.client),
+    });
+    const source = { kind: "cron", label: "Repo check" };
+
+    act(() => {
+      fake.emit("chat-cron-stream", {
+        event: "delta",
+        chat_id: "chat-cron-stream",
+        text: "Repo ",
+        source,
+      });
+      fake.emit("chat-cron-stream", {
+        event: "stream_end",
+        chat_id: "chat-cron-stream",
+        source,
+      });
+      fake.emit("chat-cron-stream", {
+        event: "turn_end",
+        chat_id: "chat-cron-stream",
+      });
+    });
+
+    expect(result.current.messages[0]).toMatchObject({
+      role: "assistant",
+      content: "Repo ",
+      isStreaming: false,
+      source,
+    });
+  });
+
+  it("preserves proactive automation source metadata on stream_end final text", () => {
+    const fake = fakeClient();
+    const { result } = renderHook(() => useNanobotStream("chat-cron-stream-end", EMPTY_MESSAGES), {
+      wrapper: wrap(fake.client),
+    });
+    const source = { kind: "cron", label: "Repo check" };
+
+    act(() => {
+      fake.emit("chat-cron-stream-end", {
+        event: "stream_end",
+        chat_id: "chat-cron-stream-end",
+        text: "Repo clean.",
+        source,
+      });
+    });
+
+    expect(result.current.messages[0]).toMatchObject({
+      role: "assistant",
+      content: "Repo clean.",
+      isStreaming: true,
+      source,
+    });
+  });
+
   it("does not start streaming from completed trailing activity after an answer", () => {
     const fake = fakeClient();
     const initialMessages = [