fix(ai-chat): keep thinking dots visible between streamed steps

showTypingIndicator hid the standalone thinking dots for any non-empty
trailing text part, so during the pause after the model finished an
intermediate narration and before its next step (e.g. a tool call) the
UI looked frozen. Suppress the dots only while the text part is still
streaming: a finalized ("done") trailing text part on an in-flight turn
now shows the dots again, matching the function's documented intent.

- message-list: guard the text branch with state !== "done" (AI SDK v6
  TextUIPart.state); stateless parts keep their previous behavior
- show-typing-indicator.test: add done -> shown and streaming -> hidden cases

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

apps/client/src/features/ai-chat/components/message-list.tsx

@@ -50,7 +50,9 @@ const BOTTOM_THRESHOLD = 40;
  * assistant message's LAST part is not live output:
  *  - the last message is still the user's (assistant hasn't started a row), or
  *  - the assistant row has no parts yet, or
- *  - its last part is an empty/whitespace text part, or
+ *  - its last part is an empty/whitespace text part, or a finished ("done")
+ *    text part while the turn continues (the model paused after some narration
+ *    and is thinking about its next step), or
  *  - its last part is a finished/errored tool (the model is thinking about the
  *    next step between tool calls).
  * It hides only while output is actively rendering: a non-empty streaming text
@@ -64,7 +66,19 @@ export function showTypingIndicator(messages: UIMessage[], isStreaming: boolean)
   const lastPart = last.parts[last.parts.length - 1];
   if (!lastPart) return true; // assistant row exists but has no parts yet.
   // The answer text is actively streaming in -> MessageItem renders it; no dots.
-  if (lastPart.type === "text" && lastPart.text.trim().length > 0) return false;
+  // Only while it is STILL streaming, though: once a non-empty text part is
+  // finalized ("done") but the turn is still in flight, the model has paused
+  // after some narration and is working on its next step (e.g. about to call a
+  // tool) — nothing is visibly progressing, so the dots must show. A text part
+  // without a `state` is treated as still-rendering (kept suppressed); this
+  // branch only runs while streaming, where live parts always carry a state.
+  if (
+    lastPart.type === "text" &&
+    lastPart.text.trim().length > 0 &&
+    (lastPart as { state?: "streaming" | "done" }).state !== "done"
+  ) {
+    return false;
+  }
   // A tool still in flight shows its own Loader in ToolCallCard -> no dots.
   if (
     isToolPart(lastPart.type) &&

apps/client/src/features/ai-chat/components/show-typing-indicator.test.ts

@@ -82,4 +82,14 @@ describe("showTypingIndicator", () => {
       showTypingIndicator([msg("assistant", [doneTool, text])], true),
     ).toBe(false);
   });
+
+  it("shows while streaming after a text part is finalized (paused before the next step)", () => {
+    const doneText = { type: "text", text: "Now creating the page in", state: "done" } as unknown as UIMessage["parts"][number];
+    expect(showTypingIndicator([msg("assistant", [doneText])], true)).toBe(true);
+  });
+
+  it("hides while a text part is actively streaming (state: streaming)", () => {
+    const streamingText = { type: "text", text: "Now writ", state: "streaming" } as unknown as UIMessage["parts"][number];
+    expect(showTypingIndicator([msg("assistant", [streamingText])], true)).toBe(false);
+  });
 });