fix(web): stop rendering an empty bubble for a fidelity-only text or thinking message (#105)

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-29 16:48:22 +08:00
parent cd1630ae8f
commit e9f032c965
2 changed files with 127 additions and 0 deletions
@@ -1474,3 +1474,98 @@ describe("multiple calls with a repeated tool_call_id (fallback for legacy Trace
    expect(cards[1]!.outputComplete).toBe(false); // new card waits for output as normal
  });
 });
+
+describe("fidelity-only messages render nothing (empty assistant bubble after thinking)", () => {
+  // Core emits a complete text/thinking message with an empty body when a provider attaches an
+  // opaque payload to an otherwise empty part (Gemini's thoughtSignature on a text part, GPT-5's
+  // encrypted-reasoning phase markers) — see flushText / flushThinking. It must exist so the
+  // fidelity round-trips into history; it must not become a visible item.
+  it("an empty assistant text after thinking adds no item", () => {
+    const m = createStreamModel();
+    pushMessage(m, userText("hi"));
+    pushMessage(m, thinkingMessage("pondering"));
+    pushMessage(m, assistantText(""));
+    expect(items(m).map((i) => i.kind)).toEqual(["user_text", "thinking"]);
+  });
+
+  it("a whitespace-only body counts as empty too", () => {
+    const m = createStreamModel();
+    pushMessage(m, assistantText("\n  \n"));
+    pushMessage(m, thinkingMessage("   "));
+    expect(items(m)).toEqual([]);
+  });
+
+  it("real content is unaffected, including a lone space inside real text", () => {
+    const m = createStreamModel();
+    pushMessage(m, thinkingMessage("thought"));
+    pushMessage(m, assistantText("answer"));
+    expect(items(m).map((i) => i.kind)).toEqual(["thinking", "assistant_text"]);
+    expect((items(m)[1] as AssistantTextItem).text).toBe("answer");
+  });
+
+  it("a streamed segment is still settled by its complete message, not dropped", () => {
+    // The guard must only skip the append path — a fragment that streamed real content is
+    // replaced by its complete message as before.
+    const m = createStreamModel();
+    pushMessage(m, partialText("start", "Hel"));
+    pushMessage(m, partialText("delta", "lo"));
+    pushMessage(m, partialText("stop"));
+    pushMessage(m, assistantText("Hello"));
+    const texts = items(m).filter((i) => i.kind === "assistant_text");
+    expect(texts).toHaveLength(1);
+    expect((texts[0] as AssistantTextItem).text).toBe("Hello");
+    expect((texts[0] as AssistantTextItem).streaming).toBe(false);
+  });
+
+  // A blank body can also arrive through a fragment: core starts a text segment on the first
+  // truthy delta (`if (!item.text) break;`), and "\n\n" is truthy, so a whitespace-only segment
+  // really does stream. Guarding only the append path would leave live and after-refresh
+  // disagreeing — the fragment kept a blank bubble that a reload then dropped.
+  it("a blank streamed text segment is discarded, so live matches the history rebuild", () => {
+    const live = createStreamModel();
+    pushMessage(live, thinkingMessage("pondering"));
+    pushMessage(live, partialText("start", "\n\n"));
+    pushMessage(live, partialText("stop"));
+    pushMessage(live, assistantText("\n\n"));
+
+    const history = createStreamModel();
+    pushMessage(history, thinkingMessage("pondering"));
+    pushMessage(history, assistantText("\n\n"));
+
+    expect(items(live).map((i) => i.kind)).toEqual(["thinking"]);
+    expect(items(live).map((i) => i.kind)).toEqual(items(history).map((i) => i.kind));
+  });
+
+  it("a blank streamed thinking segment is discarded too", () => {
+    const live = createStreamModel();
+    pushMessage(live, partialThinking("start", "  "));
+    pushMessage(live, partialThinking("stop"));
+    pushMessage(live, thinkingMessage("  "));
+
+    const history = createStreamModel();
+    pushMessage(history, thinkingMessage("  "));
+
+    expect(items(live)).toEqual([]);
+    expect(items(history)).toEqual([]);
+  });
+
+  it("discarding a blank fragment clears the open-fragment slots, leaving no stuck spinner", () => {
+    // The fragment must be removed rather than blanked: a leftover openText would keep
+    // `streaming: true` forever (a permanent blinking cursor), and a stale pendingText would
+    // let the next complete message replace the wrong item.
+    const m = createStreamModel();
+    pushMessage(m, partialText("start", " "));
+    pushMessage(m, partialText("stop"));
+    pushMessage(m, assistantText(" "));
+    expect(items(m)).toEqual([]);
+
+    // The next real reply must append cleanly, not resurrect the discarded fragment.
+    pushMessage(m, partialText("start", "Hi"));
+    pushMessage(m, partialText("stop"));
+    pushMessage(m, assistantText("Hi"));
+    const texts = items(m).filter((i) => i.kind === "assistant_text");
+    expect(texts).toHaveLength(1);
+    expect((texts[0] as AssistantTextItem).text).toBe("Hi");
+    expect((texts[0] as AssistantTextItem).streaming).toBe(false);
+  });
+});