feat(web): make thread errors copyable

apps/web/src/components/ChatView.tsx

@@ -6288,6 +6288,7 @@ function ChatViewContent(props: ChatViewProps) {
 
         <ThreadErrorBanner
           error={visibleThreadError}
+          key={threadErrorBannerKey}
           onDismiss={() => {
             setThreadError(activeThread.id, null);
             dismissThreadErrorBannerForSession(threadErrorBannerKey);

apps/web/src/components/chat/ThreadErrorBanner.test.tsx

@@ -1,13 +1,19 @@
 import { renderToStaticMarkup } from "react-dom/server";
-import { describe, expect, it } from "vite-plus/test";
+import { afterEach, describe, expect, it, vi } from "vite-plus/test";
 
 import {
   dismissThreadErrorBannerForSession,
   getThreadErrorBannerKey,
   isThreadErrorBannerDismissedForSession,
+  showThreadErrorCopyFailure,
   shouldShowThreadErrorBanner,
   ThreadErrorBanner,
 } from "./ThreadErrorBanner";
+import { anchoredToastManager } from "../ui/toast";
+
+afterEach(() => {
+  vi.restoreAllMocks();
+});
 
 describe("ThreadErrorBanner", () => {
   it("stays hidden after its current error is dismissed", () => {
@@ -51,6 +57,12 @@ describe("ThreadErrorBanner", () => {
     ).toBe(true);
   });
 
+  it("gives identical diagnostics on different threads distinct render identities", () => {
+    expect(getThreadErrorBannerKey("env:thread-c", "Aborted")).not.toBe(
+      getThreadErrorBannerKey("env:other-thread", "Aborted"),
+    );
+  });
+
   it("keeps a dismissal across visiting threads with no error", () => {
     const bannerKey = getThreadErrorBannerKey("env:thread-d", "Aborted");
     dismissThreadErrorBannerForSession(bannerKey);
@@ -69,7 +81,8 @@ describe("ThreadErrorBanner", () => {
   it("never shows a null error", () => {
     expect(shouldShowThreadErrorBanner("env:thread-e", null, false)).toBe(false);
   });
-  it("aligns the warning and dismiss icons with the first line of a multi-line error", () => {
+
+  it("offers copy and aligns the controls with the first line of a multi-line error", () => {
     const markup = renderToStaticMarkup(
       <ThreadErrorBanner
         error={"The first error line\ncontinues on a second line"}
@@ -78,11 +91,30 @@ describe("ThreadErrorBanner", () => {
     );
 
     expect(markup).toContain('role="alert"');
+    expect(markup).toContain('aria-label="Copy error"');
+    expect(markup).toContain("lucide-copy text-error");
     expect(markup).toContain('aria-label="Dismiss error"');
     expect(markup).not.toContain("controlAlignment");
     expect(markup).toContain("flex gap-2 items-start");
     expect(markup).toContain("min-h-7 pt-1 sm:min-h-6 sm:pt-0.5");
     expect(markup).toContain("h-lh w-4");
     expect(markup).toContain("h-lh self-start");
   });
+
+  it("shows anchored feedback when copying fails", () => {
+    const addToast = vi
+      .spyOn(anchoredToastManager, "add")
+      .mockImplementation(() => undefined as never);
+    const anchor = {} as HTMLButtonElement;
+
+    showThreadErrorCopyFailure(anchor, new Error("Clipboard access was denied."));
+
+    expect(addToast).toHaveBeenCalledWith({
+      data: { tooltipStyle: true },
+      positionerProps: { anchor },
+      timeout: 1000,
+      title: "Failed to copy",
+      description: "Clipboard access was denied.",
+    });
+  });
 });

apps/web/src/components/chat/ThreadErrorBanner.tsx

@@ -1,8 +1,56 @@
-import { memo } from "react";
+import { memo, useRef } from "react";
 import { Alert, AlertAction, AlertDescription } from "../ui/alert";
 import { Button } from "../ui/button";
-import { CircleAlertIcon, XIcon } from "lucide-react";
+import { CheckIcon, CircleAlertIcon, CopyIcon, XIcon } from "lucide-react";
 import { Tooltip, TooltipPopup, TooltipTrigger } from "../ui/tooltip";
+import { useCopyToClipboard } from "~/hooks/useCopyToClipboard";
+import { anchoredToastManager } from "../ui/toast";
+
+const COPY_FEEDBACK_TIMEOUT_MS = 1000;
+
+export function showThreadErrorCopyFailure(
+  anchor: HTMLButtonElement | null,
+  copyError: Error,
+): void {
+  if (!anchor) return;
+  anchoredToastManager.add({
+    data: { tooltipStyle: true },
+    positionerProps: { anchor },
+    timeout: COPY_FEEDBACK_TIMEOUT_MS,
+    title: "Failed to copy",
+    description: copyError.message,
+  });
+}
+
+function ThreadErrorCopyButton({ error }: { error: string }) {
+  const buttonRef = useRef<HTMLButtonElement>(null);
+  const { copyToClipboard, isCopied } = useCopyToClipboard({
+    target: "error-message",
+    timeout: COPY_FEEDBACK_TIMEOUT_MS,
+    onError: (copyError) => showThreadErrorCopyFailure(buttonRef.current, copyError),
+  });
+  const copyLabel = isCopied ? "Copied error" : "Copy error";
+
+  return (
+    <Tooltip>
+      <TooltipTrigger
+        render={
+          <Button
+            variant="ghost"
+            size="icon-xs"
+            aria-label={copyLabel}
+            onClick={() => copyToClipboard(error)}
+            ref={buttonRef}
+            type="button"
+          />
+        }
+      >
+        {isCopied ? <CheckIcon className="text-success!" /> : <CopyIcon className="text-error" />}
+      </TooltipTrigger>
+      <TooltipPopup side="top">{copyLabel}</TooltipPopup>
+    </Tooltip>
+  );
+}
 
 export function getThreadErrorBannerKey(threadKey: string, error: string | null): string | null {
   return error === null ? null : `${threadKey}\u0000${error}`;
@@ -41,6 +89,7 @@ export const ThreadErrorBanner = memo(function ThreadErrorBanner({
   onDismiss?: () => void;
 }) {
   if (!error) return null;
+
   return (
     <div className="mx-auto w-fit max-w-[min(48rem,calc(100%-2rem))] pt-3">
       <Alert variant="error" controlAlignment="first-line">
@@ -53,13 +102,14 @@ export const ThreadErrorBanner = memo(function ThreadErrorBanner({
             </TooltipPopup>
           </Tooltip>
         </AlertDescription>
-        {onDismiss && (
-          <AlertAction>
+        <AlertAction>
+          <ThreadErrorCopyButton error={error} />
+          {onDismiss && (
             <Button variant="ghost" size="icon-xs" aria-label="Dismiss error" onClick={onDismiss}>
               <XIcon className="text-destructive" />
             </Button>
-          </AlertAction>
-        )}
+          )}
+        </AlertAction>
       </Alert>
     </div>
   );

apps/web/src/hooks/useCopyToClipboard.test.ts

@@ -1,16 +1,100 @@
+import type { Dispatch, SetStateAction } from "react";
 import { afterEach, describe, expect, it, vi } from "vite-plus/test";
 
+const hooks = vi.hoisted(() => {
+  let cursor = 0;
+  let slots: unknown[] = [];
+
+  const nextIndex = () => cursor++;
+  const unmount = () => {
+    for (const slot of slots) {
+      if (
+        typeof slot === "object" &&
+        slot !== null &&
+        "effectCleanup" in slot &&
+        typeof slot.effectCleanup === "function"
+      ) {
+        slot.effectCleanup();
+        slot.effectCleanup = undefined;
+      }
+    }
+  };
+
+  return {
+    beginRender() {
+      cursor = 0;
+    },
+    reset() {
+      unmount();
+      cursor = 0;
+      slots = [];
+    },
+    unmount,
+    useCallback<T>(callback: T): T {
+      nextIndex();
+      return callback;
+    },
+    useEffect(effect: () => void | (() => void)): void {
+      const index = nextIndex();
+      if (slots[index] === undefined) {
+        slots[index] = { effectCleanup: effect() };
+      }
+    },
+    useRef<T>(initialValue: T): { current: T } {
+      const index = nextIndex();
+      if (slots[index] === undefined) {
+        slots[index] = { current: initialValue };
+      }
+      return slots[index] as { current: T };
+    },
+    useState<T>(initialValue: T | (() => T)): [T, Dispatch<SetStateAction<T>>] {
+      const index = nextIndex();
+      if (slots[index] === undefined) {
+        slots[index] =
+          typeof initialValue === "function" ? (initialValue as () => T)() : initialValue;
+      }
+      const setValue: Dispatch<SetStateAction<T>> = (nextValue) => {
+        const previous = slots[index] as T;
+        slots[index] =
+          typeof nextValue === "function" ? (nextValue as (value: T) => T)(previous) : nextValue;
+      };
+      return [slots[index] as T, setValue];
+    },
+  };
+});
+
+vi.mock("react", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("react")>();
+  return {
+    ...actual,
+    useCallback: hooks.useCallback,
+    useEffect: hooks.useEffect,
+    useRef: hooks.useRef,
+    useState: hooks.useState,
+  };
+});
+
 import {
   ClipboardApiUnavailableError,
   ClipboardWriteError,
+  useCopyToClipboard,
   writeTextToClipboard,
 } from "./useCopyToClipboard";
 
-describe("writeTextToClipboard", () => {
-  afterEach(() => {
-    vi.unstubAllGlobals();
-  });
+async function flushClipboardWrite(): Promise<void> {
+  await Promise.resolve();
+  await Promise.resolve();
+  await Promise.resolve();
+}
+
+afterEach(() => {
+  hooks.reset();
+  vi.useRealTimers();
+  vi.restoreAllMocks();
+  vi.unstubAllGlobals();
+});
 
+describe("writeTextToClipboard", () => {
   it("reports unavailable clipboard support with structural context", async () => {
     vi.stubGlobal("window", {});
     vi.stubGlobal("navigator", {});
@@ -55,4 +139,118 @@ describe("writeTextToClipboard", () => {
     await expect(writeTextToClipboard("", "plan")).resolves.toBe(false);
     expect(writeText).not.toHaveBeenCalled();
   });
+
+  it("writes the complete multiline value without transforming it", async () => {
+    const writeText = vi.fn().mockResolvedValue(undefined);
+    vi.stubGlobal("window", {});
+    vi.stubGlobal("navigator", { clipboard: { writeText } });
+    const diagnostic = "Provider failed\ncaused by: socket closed\nrequest id: abc-123";
+
+    await expect(writeTextToClipboard(diagnostic, "error-message")).resolves.toBe(true);
+
+    expect(writeText).toHaveBeenCalledWith(diagnostic);
+  });
+});
+
+describe("useCopyToClipboard", () => {
+  it("shows copied state only after success and resets it after the timeout", async () => {
+    vi.useFakeTimers();
+    const writeText = vi.fn().mockResolvedValue(undefined);
+    const onCopy = vi.fn();
+    vi.stubGlobal("window", {});
+    vi.stubGlobal("navigator", { clipboard: { writeText } });
+    const options = { timeout: 1000, onCopy };
+
+    hooks.beginRender();
+    const initial = useCopyToClipboard<string>(options);
+    initial.copyToClipboard("complete diagnostic", "thread-a");
+    await flushClipboardWrite();
+
+    hooks.beginRender();
+    expect(useCopyToClipboard<string>(options).isCopied).toBe(true);
+    expect(onCopy).toHaveBeenCalledWith("thread-a");
+
+    vi.advanceTimersByTime(1000);
+    hooks.beginRender();
+    expect(useCopyToClipboard<string>(options).isCopied).toBe(false);
+  });
+
+  it("clears copied feedback when a repeat attempt fails", async () => {
+    vi.useFakeTimers();
+    const cause = new Error("clipboard permission revoked");
+    const writeText = vi.fn().mockResolvedValueOnce(undefined).mockRejectedValueOnce(cause);
+    const onError = vi.fn();
+    const errorLog = vi.spyOn(console, "error").mockImplementation(() => {});
+    vi.stubGlobal("window", {});
+    vi.stubGlobal("navigator", { clipboard: { writeText } });
+    const options = { timeout: 1000, target: "error-message", onError };
+
+    hooks.beginRender();
+    let current = useCopyToClipboard<string>(options);
+    current.copyToClipboard("first diagnostic", "thread-a");
+    await flushClipboardWrite();
+
+    hooks.beginRender();
+    current = useCopyToClipboard<string>(options);
+    expect(current.isCopied).toBe(true);
+    current.copyToClipboard("second diagnostic", "thread-a");
+
+    hooks.beginRender();
+    expect(useCopyToClipboard<string>(options).isCopied).toBe(false);
+    await flushClipboardWrite();
+
+    expect(onError).toHaveBeenCalledWith(
+      expect.objectContaining({ cause, target: "error-message" }),
+      "thread-a",
+    );
+    expect(errorLog).toHaveBeenCalledTimes(1);
+    expect(vi.getTimerCount()).toBe(0);
+  });
+
+  it("ignores stale completions from an earlier copy attempt", async () => {
+    let resolveFirstWrite!: () => void;
+    const firstWrite = new Promise<void>((resolve) => {
+      resolveFirstWrite = resolve;
+    });
+    const writeText = vi.fn().mockReturnValueOnce(firstWrite).mockResolvedValueOnce(undefined);
+    const onCopy = vi.fn();
+    vi.stubGlobal("window", {});
+    vi.stubGlobal("navigator", { clipboard: { writeText } });
+    const options = { timeout: 0, onCopy };
+
+    hooks.beginRender();
+    const current = useCopyToClipboard<string>(options);
+    current.copyToClipboard("older diagnostic", "older");
+    current.copyToClipboard("newer diagnostic", "newer");
+    await flushClipboardWrite();
+
+    expect(onCopy).toHaveBeenCalledOnce();
+    expect(onCopy).toHaveBeenCalledWith("newer");
+
+    resolveFirstWrite();
+    await flushClipboardWrite();
+    expect(onCopy).toHaveBeenCalledOnce();
+  });
+
+  it("ignores a pending clipboard completion after unmount", async () => {
+    vi.useFakeTimers();
+    let resolveWrite!: () => void;
+    const pendingWrite = new Promise<void>((resolve) => {
+      resolveWrite = resolve;
+    });
+    const writeText = vi.fn().mockReturnValue(pendingWrite);
+    const onCopy = vi.fn();
+    vi.stubGlobal("window", {});
+    vi.stubGlobal("navigator", { clipboard: { writeText } });
+
+    hooks.beginRender();
+    const current = useCopyToClipboard<void>({ onCopy });
+    current.copyToClipboard("diagnostic");
+    hooks.unmount();
+    resolveWrite();
+    await flushClipboardWrite();
+
+    expect(onCopy).not.toHaveBeenCalled();
+    expect(vi.getTimerCount()).toBe(0);
+  });
 });