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/ContentViewer/ContentViewer.test.tsx

@@ -0,0 +1,107 @@
+import { describe, it, expect } from "vitest";
+import type { ContentBlock } from "@modelcontextprotocol/sdk/types.js";
+import { renderWithMantine, screen } from "../../../test/renderWithMantine";
+import { ContentViewer } from "./ContentViewer";
+
+describe("ContentViewer", () => {
+  it("renders text content as-is when not JSON", () => {
+    const block: ContentBlock = { type: "text", text: "hello world" };
+    renderWithMantine(<ContentViewer block={block} />);
+    expect(screen.getByText("hello world")).toBeInTheDocument();
+  });
+
+  it("pretty-prints JSON text", () => {
+    const block: ContentBlock = { type: "text", text: '{"a":1}' };
+    renderWithMantine(<ContentViewer block={block} />);
+    expect(screen.getByText(/"a": 1/)).toBeInTheDocument();
+  });
+
+  it("falls back to raw text when JSON is malformed", () => {
+    const block: ContentBlock = { type: "text", text: "{ broken" };
+    renderWithMantine(<ContentViewer block={block} />);
+    expect(screen.getByText("{ broken")).toBeInTheDocument();
+  });
+
+  it("renders a copy overlay when copyable", () => {
+    const block: ContentBlock = { type: "text", text: "hello" };
+    renderWithMantine(<ContentViewer block={block} copyable />);
+    expect(screen.getByRole("button")).toBeInTheDocument();
+  });
+
+  it("does not render a copy overlay by default", () => {
+    const block: ContentBlock = { type: "text", text: "hello" };
+    renderWithMantine(<ContentViewer block={block} />);
+    expect(screen.queryByRole("button")).not.toBeInTheDocument();
+  });
+
+  it("renders an image block", () => {
+    const block: ContentBlock = {
+      type: "image",
+      mimeType: "image/png",
+      data: "AAAA",
+    };
+    renderWithMantine(<ContentViewer block={block} />);
+    expect(screen.getByRole("img")).toHaveAttribute(
+      "src",
+      "data:image/png;base64,AAAA",
+    );
+  });
+
+  it("renders an audio block", () => {
+    const block: ContentBlock = {
+      type: "audio",
+      mimeType: "audio/mp3",
+      data: "BBBB",
+    };
+    const { container } = renderWithMantine(<ContentViewer block={block} />);
+    const source = container.querySelector("source");
+    expect(source).toHaveAttribute("src", "data:audio/mp3;base64,BBBB");
+  });
+
+  it("renders a text resource block", () => {
+    const block: ContentBlock = {
+      type: "resource",
+      resource: { uri: "file:///foo", text: "embedded text" },
+    };
+    renderWithMantine(<ContentViewer block={block} />);
+    expect(screen.getByText("embedded text")).toBeInTheDocument();
+  });
+
+  it("renders a blob resource block with placeholder", () => {
+    const block: ContentBlock = {
+      type: "resource",
+      resource: {
+        uri: "file:///bar",
+        blob: "abc",
+        mimeType: "application/octet-stream",
+      },
+    };
+    renderWithMantine(<ContentViewer block={block} />);
+    expect(screen.getByText("[blob: file:///bar]")).toBeInTheDocument();
+  });
+
+  it("renders a resource_link with name", () => {
+    const block: ContentBlock = {
+      type: "resource_link",
+      uri: "ui://app",
+      name: "Cool App",
+    };
+    renderWithMantine(<ContentViewer block={block} />);
+    expect(screen.getByText("Cool App")).toBeInTheDocument();
+  });
+
+  it("falls back to URI when resource_link has no name", () => {
+    const block = {
+      type: "resource_link",
+      uri: "ui://app",
+    } as unknown as ContentBlock;
+    renderWithMantine(<ContentViewer block={block} />);
+    expect(screen.getByText("ui://app")).toBeInTheDocument();
+  });
+
+  it("renders nothing for unknown block types", () => {
+    renderWithMantine(<ContentViewer block={{ type: "unknown" } as never} />);
+    expect(screen.queryByRole("img")).not.toBeInTheDocument();
+    expect(screen.queryByRole("button")).not.toBeInTheDocument();
+  });
+});