fix: preserve model reasoning when visible response is empty

When a model generates only a reasoning block (<think>...</think>) with no visible content, the reasoning was previously lost because the DB insert omitted the reasoning_content column while using a fallback error message.

This separates the hasReasoningOnly condition from the corrupted/transcript leakage conditions, ensuring the reasoning is properly saved and the user sees a specific placeholder.

tauri-app/src/components/ChatView.test.tsx

@@ -3,6 +3,7 @@
 import { createRoot, type Root } from "react-dom/client";
 import { act } from "react-dom/test-utils";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { parseAssistantResponse } from "../lib/chat";
 import type { DB } from "../lib/db";
 import ChatView from "./ChatView";
 import type { Message } from "../lib/types";
@@ -26,7 +27,7 @@ const defaultChatViewProps = {
   status: "error" as import("../lib/types").ServerStatus,
 };
 
-describe("ChatView", () => {
+describe.sequential("ChatView", () => {
   let container: HTMLDivElement;
   let root: Root;
 
@@ -43,6 +44,7 @@ describe("ChatView", () => {
     act(() => root.unmount());
     container.remove();
     vi.restoreAllMocks();
+    vi.unstubAllGlobals();
     // @ts-expect-error React test environment flag
     globalThis.IS_REACT_ACT_ENVIRONMENT = false;
   });
@@ -78,7 +80,7 @@ describe("ChatView", () => {
     });
 
     expect(textarea?.value).toBe("Keep this draft");
-    expect(container.textContent).toContain("Runtime offline");
+    expect(container.textContent).toContain("Connect runtime");
     expect(vi.mocked(db.run)).not.toHaveBeenCalled();
   });
 
@@ -251,7 +253,7 @@ describe("ChatView", () => {
       textarea!.dispatchEvent(new Event("input", { bubbles: true }));
     });
 
-    const sendButton = Array.from(container.querySelectorAll("button")).find((node) => node.textContent?.includes("Send"));
+    const sendButton = container.querySelector('[aria-label="Send message"]') as HTMLButtonElement | null;
     expect(sendButton).toBeTruthy();
 
     await act(async () => {
@@ -295,6 +297,115 @@ describe("ChatView", () => {
     expect(container.textContent).not.toContain("Late answer from first chat");
   });
 
+  it("sanitizes leaked assistant transcript before sending history back to the model", async () => {
+    // The DB now stores already-cleaned content (leakage is stripped before insert).
+    // buildApiMessages trusts the DB content and only drops fully-corrupted rows.
+    // Messages that were fully leakage (no useful prefix) are saved as a ⚠️ placeholder
+    // and excluded by the NOT LIKE '⚠️%' filter, so they never reach the model.
+    const rowsByChat = new Map<number, Message[]>([
+      [1, [
+        { id: 11, chat_id: 1, role: "user", content: "Mensagem anterior", created_at: 1 },
+        {
+          id: 12,
+          chat_id: 1,
+          role: "assistant",
+          // Simulates what is stored AFTER leakage strip: only the useful prefix.
+          content: "Resposta útil.",
+          created_at: 2,
+        },
+        // id: 13 was fully corrupted (no useful prefix), saved as ⚠️ placeholder.
+        // It is excluded by the NOT LIKE '⚠️%' filter in buildApiMessages.
+      ]],
+    ]);
+
+    const db = {
+      insert: vi.fn(() => 1),
+      query: vi.fn((sql: string, params?: unknown[]) => {
+        if (sql.includes("SELECT role, content FROM messages WHERE chat_id = ?")) {
+          return [...(rowsByChat.get(Number(params?.[0])) ?? [])].map(({ role, content }) => ({ role, content }));
+        }
+        if (sql.includes("FROM messages WHERE chat_id = ?")) {
+          return [...(rowsByChat.get(Number(params?.[0])) ?? [])];
+        }
+        return [];
+      }),
+      get: vi.fn((sql: string, params?: unknown[]) => {
+        if (sql.includes("COUNT(*) as c FROM messages WHERE chat_id = ?")) {
+          return { c: rowsByChat.get(Number(params?.[0]))?.length ?? 0 };
+        }
+        return null;
+      }),
+      run: vi.fn((sql: string, params?: unknown[]) => {
+        if (sql.includes("INSERT INTO messages (chat_id, role, content) VALUES (?, 'user', ?)")) {
+          const chatId = Number(params?.[0]);
+          const content = String(params?.[1] ?? "");
+          const next = rowsByChat.get(chatId) ?? [];
+          next.push({ id: 99, chat_id: chatId, role: "user", content, created_at: 99 });
+          rowsByChat.set(chatId, next);
+        }
+      }),
+      persist: vi.fn(),
+    } as unknown as DB;
+
+    const fetchSpy = vi.fn(() =>
+      Promise.resolve(
+        new Response(
+          new ReadableStream({
+            start(controller) {
+              controller.enqueue(new TextEncoder().encode("data: [DONE]\n"));
+              controller.close();
+            },
+          }),
+          { status: 200, headers: { "Content-Type": "text/event-stream" } },
+        ),
+      ),
+    );
+    vi.stubGlobal("fetch", fetchSpy);
+
+    await act(async () => {
+      root.render(
+        <ChatView
+          db={db}
+          chatId={1}
+          server="http://127.0.0.1:1234"
+          apiKey=""
+          model="demo"
+          onChatCreated={vi.fn()}
+          onChatUpdated={vi.fn()}
+          {...defaultChatViewProps}
+        />,
+      );
+    });
+
+    const textarea = container.querySelector("textarea") as HTMLTextAreaElement | null;
+    expect(textarea).toBeTruthy();
+    const setTextareaValue = Object.getOwnPropertyDescriptor(HTMLTextAreaElement.prototype, "value")?.set;
+
+    await act(async () => {
+      setTextareaValue?.call(textarea, "Nova pergunta");
+      textarea!.dispatchEvent(new Event("input", { bubbles: true }));
+    });
+
+    const sendButton = container.querySelector('[aria-label="Send message"]') as HTMLButtonElement | null;
+    await act(async () => {
+      sendButton?.click();
+      await Promise.resolve();
+    });
+
+    expect(fetchSpy).toHaveBeenCalledTimes(1);
+    const call = fetchSpy.mock.calls[0] as unknown as [string, RequestInit];
+    const [, init] = call;
+    const body = JSON.parse(String(init.body));
+
+    // System prompt is always prepended as the first message
+    expect(body.messages[0].role).toBe("system");
+    expect(body.messages.slice(1)).toEqual([
+      { role: "user", content: "Nova pergunta" },
+      { role: "assistant", content: "Resposta útil." },
+      { role: "user", content: "Mensagem anterior" },
+    ]);
+  });
+
   it("shows assistant reply after generation completes in an existing chat", async () => {
     const rowsByChat = new Map<number, Message[]>([
       [1, [{ id: 11, chat_id: 1, role: "user", content: "Previous message", created_at: 1 }]],
@@ -374,7 +485,7 @@ describe("ChatView", () => {
       textarea!.dispatchEvent(new Event("input", { bubbles: true }));
     });
 
-    const sendButton = Array.from(container.querySelectorAll("button")).find((node) => node.textContent?.includes("Send"));
+    const sendButton = container.querySelector('[aria-label="Send message"]') as HTMLButtonElement | null;
     await act(async () => { sendButton?.click(); });
 
     // During generation, user message should be visible
@@ -446,7 +557,7 @@ describe("ChatView", () => {
       textarea!.dispatchEvent(new Event("input", { bubbles: true }));
     });
 
-    const sendButton = Array.from(container.querySelectorAll("button")).find((node) => node.textContent?.includes("Send"));
+    const sendButton = container.querySelector('[aria-label="Send message"]') as HTMLButtonElement | null;
     expect(sendButton).toBeTruthy();
 
     await act(async () => {
@@ -478,4 +589,102 @@ describe("ChatView", () => {
 
     expect(requestSignal.aborted).toBe(true);
   });
+
+  it("derives visible content and reasoning from think blocks before persistence", () => {
+    const parsed = parseAssistantResponse("<think>analise interna</think>Resposta util final");
+
+    expect(parsed.content).toBe("Resposta util final");
+    expect(parsed.reasoning).toBe("analise interna");
+    expect(parsed.thinkingOpen).toBe(false);
+  });
+
+  it("stores a controlled placeholder when the model starts inside a leaked code fence transcript", async () => {
+    const rowsByChat = new Map<number, Message[]>([[1, []]]);
+    let nextMessageId = 1;
+    const db = {
+      insert: vi.fn(() => 1),
+      query: vi.fn((sql: string, params?: unknown[]) => {
+        if (sql.includes("FROM messages WHERE chat_id = ?")) {
+          return [...(rowsByChat.get(Number(params?.[0])) ?? [])];
+        }
+        return [];
+      }),
+      get: vi.fn(() => null),
+      run: vi.fn((sql: string, params?: unknown[]) => {
+        if (sql.includes("INSERT INTO messages (chat_id, role, content) VALUES (?, 'user', ?)")) {
+          const chatId = Number(params?.[0]);
+          const content = String(params?.[1] ?? "");
+          const next = rowsByChat.get(chatId) ?? [];
+          next.push({ id: nextMessageId++, chat_id: chatId, role: "user", content, created_at: nextMessageId });
+          rowsByChat.set(chatId, next);
+        }
+        if (sql.includes("INSERT INTO messages (chat_id, role, content) VALUES (?, 'assistant', ?)")) {
+          const chatId = Number(params?.[0]);
+          const content = String(params?.[1] ?? "");
+          const next = rowsByChat.get(chatId) ?? [];
+          next.push({ id: nextMessageId++, chat_id: chatId, role: "assistant", content, created_at: nextMessageId });
+          rowsByChat.set(chatId, next);
+        }
+      }),
+      persist: vi.fn(),
+    } as unknown as DB;
+
+    vi.stubGlobal(
+      "fetch",
+      vi.fn(() =>
+        Promise.resolve(
+          new Response(
+            new ReadableStream({
+              start(controller) {
+                const encoder = new TextEncoder();
+                controller.enqueue(encoder.encode("data: {\"choices\":[{\"delta\":{\"content\":\"\\n\\n```python\\n# System: You are a precise coding assistant running locally.\\nUser: teste mensagem\\nAssistant: ```\"}}]}\n"));
+                controller.enqueue(encoder.encode("data: [DONE]\n"));
+                controller.close();
+              },
+            }),
+            { status: 200, headers: { "Content-Type": "text/event-stream" } },
+          ),
+        ),
+      ),
+    );
+
+    await act(async () => {
+      root.render(
+        <ChatView
+          db={db}
+          chatId={1}
+          server="http://127.0.0.1:1234"
+          apiKey=""
+          model="demo"
+          onChatCreated={vi.fn()}
+          onChatUpdated={vi.fn()}
+          {...defaultChatViewProps}
+        />,
+      );
+    });
+
+    const textarea = container.querySelector("textarea") as HTMLTextAreaElement | null;
+    const sendButton = container.querySelector('[aria-label="Send message"]') as HTMLButtonElement | null;
+    const setTextareaValue = Object.getOwnPropertyDescriptor(HTMLTextAreaElement.prototype, "value")?.set;
+
+    await act(async () => {
+      setTextareaValue?.call(textarea, "teste mensagem");
+      textarea!.dispatchEvent(new Event("input", { bubbles: true }));
+      sendButton?.click();
+      await new Promise((resolve) => setTimeout(resolve, 0));
+      await new Promise((resolve) => setTimeout(resolve, 0));
+      await new Promise((resolve) => setTimeout(resolve, 0));
+    });
+
+    const runCalls = vi.mocked(db.run).mock.calls as Array<[string, unknown[]?]>;
+    expect(
+      runCalls.some(
+        ([sql, params]) =>
+          sql === "INSERT INTO messages (chat_id, role, content) VALUES (?, 'assistant', ?)"
+          && Array.isArray(params)
+          && params[0] === 1
+          && params[1] === "⚠️ O modelo gerou uma resposta corrompida ou vazou o prompt de sistema.",
+      ),
+    ).toBe(true);
+  });
 });