test(coverage): bootstrap vitest unit infra and add tests at 90%+ per file (#1245) (#1269)

* test(coverage): bootstrap vitest unit infra and add tests at 90%+ per file (#1245)

Establishes the unit-test runtime AGENTS.md mandates: a vitest "unit"
project alongside the existing storybook project, RTL + jest-dom +
happy-dom, a Mantine-aware render helper, and a 90%-line per-file
coverage gate enforced by CI. Adds 66 test files covering all 62
components under elements/groups/screens/views, plus core/mcp and
clients/web/src/utils. Total: 577 tests, 98.7% line coverage globally.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* test(coverage): address PR #1269 review feedback

- AGENTS.md: correct coverage gate description (lines ≥ 90, statements ≥ 85,
  functions ≥ 80, branches ≥ 50) with rationale for the relaxed branch
  threshold
- InspectorView.test.tsx: document what the Math.random() mock values
  (0.1 / 0.99) control vs. STUB_SUCCESS_RATE in InspectorView.tsx
- vite.config.ts / tsconfig.test.json: drop unused `globals: true` and the
  `vitest/globals` type now that every test file imports describe/it/expect/vi
  explicitly; manual `afterEach(cleanup)` in setup.ts remains required because
  testing-library auto-cleanup relies on globalThis.afterEach

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

clients/web/src/components/elements/MessageBubble/MessageBubble.test.tsx

@@ -0,0 +1,100 @@
+import { describe, it, expect } from "vitest";
+import type {
+  PromptMessage,
+  SamplingMessage,
+} from "@modelcontextprotocol/sdk/types.js";
+import { renderWithMantine, screen } from "../../../test/renderWithMantine";
+import { MessageBubble } from "./MessageBubble";
+
+describe("MessageBubble", () => {
+  it("renders a text sampling message", () => {
+    const message: SamplingMessage = {
+      role: "user",
+      content: { type: "text", text: "hello" },
+    };
+    renderWithMantine(<MessageBubble index={0} message={message} />);
+    expect(screen.getByText("[0] role: user")).toBeInTheDocument();
+    expect(screen.getByText('"hello"')).toBeInTheDocument();
+  });
+
+  it("renders a copy button when there is text", () => {
+    const message: SamplingMessage = {
+      role: "user",
+      content: { type: "text", text: "hello" },
+    };
+    renderWithMantine(<MessageBubble index={0} message={message} />);
+    expect(screen.getByRole("button")).toBeInTheDocument();
+  });
+
+  it("renders an image content block", () => {
+    const message: SamplingMessage = {
+      role: "user",
+      content: { type: "image", mimeType: "image/png", data: "AAA" },
+    };
+    renderWithMantine(<MessageBubble index={1} message={message} />);
+    expect(screen.getByRole("img")).toHaveAttribute(
+      "src",
+      "data:image/png;base64,AAA",
+    );
+  });
+
+  it("renders an audio content block", () => {
+    const message: SamplingMessage = {
+      role: "assistant",
+      content: { type: "audio", mimeType: "audio/mp3", data: "BBB" },
+    };
+    const { container } = renderWithMantine(
+      <MessageBubble index={2} message={message} />,
+    );
+    expect(container.querySelector("source")).toHaveAttribute(
+      "src",
+      "data:audio/mp3;base64,BBB",
+    );
+  });
+
+  it("renders embedded resource text from a prompt message array", () => {
+    const message: PromptMessage = {
+      role: "user",
+      content: {
+        type: "resource",
+        resource: { uri: "file:///x", text: "embedded" },
+      },
+    };
+    renderWithMantine(<MessageBubble index={3} message={message} />);
+    expect(screen.getByText('"embedded"')).toBeInTheDocument();
+  });
+
+  it("renders blob resource placeholder", () => {
+    const message: PromptMessage = {
+      role: "user",
+      content: {
+        type: "resource",
+        resource: {
+          uri: "file:///b",
+          blob: "abc",
+          mimeType: "application/octet-stream",
+        },
+      },
+    };
+    renderWithMantine(<MessageBubble index={4} message={message} />);
+    expect(screen.getByText('"[resource: file:///b]"')).toBeInTheDocument();
+  });
+
+  it("renders resource_link content", () => {
+    const message = {
+      role: "user",
+      content: { type: "resource_link", uri: "ui://app" },
+    } as unknown as PromptMessage;
+    renderWithMantine(<MessageBubble index={5} message={message} />);
+    expect(screen.getByText('"[resource: ui://app]"')).toBeInTheDocument();
+  });
+
+  it("renders fallback for unknown content types", () => {
+    const message = {
+      role: "user",
+      content: { type: "weird" },
+    } as unknown as SamplingMessage;
+    renderWithMantine(<MessageBubble index={6} message={message} />);
+    expect(screen.getByText('"[weird]"')).toBeInTheDocument();
+  });
+});