feat(check): opt-in --layout proseCoverageFloor (#2834)

* feat(check): opt-in --layout proseCoverageFloor for text_occluded

Keep the default prose coverage floor at 0.15 for all callers, and allow
stricter agents (e.g. Zephyr) to lower it via --layout "proseCoverageFloor=0.05"
without changing other layout gates.

Co-authored-by: Cursor <cursoragent@cursor.com>

* style(check): collapse --layout comments and docs to one line

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(check): strict proseCoverageFloor parse + pin 0.07 floor tests

Reject trailing-garbage fractions that Number.parseFloat would accept, and
pin the existing ~0.07 coverage fixture for default vs floor=0.05 (atomic
labels unchanged) plus a collectLayout forwarding assertion.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(check): share parseNumberStrict across layout and frame-check

Sweep the sibling --frame-check tol parser (and caption fractions) onto the
same strict Number() helper so trailing garbage cannot prefix-parse.

Co-authored-by: Cursor <cursoragent@cursor.com>

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

packages/cli/src/commands/check.test.ts

@@ -1141,6 +1141,57 @@ describe("frame-check flag grammar", () => {
     });
     expect(() => parseFrameCheck("bogus=1")).toThrow("Invalid --frame-check");
     expect(() => parseFrameCheck("tol=-2")).toThrow("Invalid --frame-check");
+    expect(() => parseFrameCheck("tol=4px")).toThrow("Invalid --frame-check");
+    expect(() => parseFrameCheck("tol=2garbage")).toThrow("Invalid --frame-check");
+  });
+});
+
+describe("layout flag grammar", () => {
+  it("parses proseCoverageFloor and rejects malformed specs", async () => {
+    const { parseLayout } = await import("./check.js");
+    expect(parseLayout(undefined)).toBeUndefined();
+    expect(parseLayout("proseCoverageFloor=0.05")).toEqual({ proseCoverageFloor: 0.05 });
+    expect(parseLayout("proseCoverageFloor=0")).toEqual({ proseCoverageFloor: 0 });
+    expect(parseLayout("proseCoverageFloor=1")).toEqual({ proseCoverageFloor: 1 });
+    expect(() => parseLayout(true)).toThrow("Invalid --layout");
+    expect(() => parseLayout("")).toThrow("Invalid --layout");
+    expect(() => parseLayout("bogus=1")).toThrow("Invalid --layout");
+    expect(() => parseLayout("proseCoverageFloor=-0.1")).toThrow("Invalid --layout");
+    expect(() => parseLayout("proseCoverageFloor=1.1")).toThrow("Invalid --layout");
+    expect(() => parseLayout("proseCoverageFloor=0.05garbage")).toThrow("Invalid --layout");
+    expect(() => parseLayout("proseCoverageFloor=0.1%")).toThrow("Invalid --layout");
+    expect(() => parseLayout("proseCoverageFloor=")).toThrow("Invalid --layout");
+  });
+
+  it("threads --layout into the check pipeline options", async () => {
+    const { report } = await runScenario(fakeDriver());
+    const runPipeline = vi.fn(async (_project: ProjectDir, _options: CheckOptions) => report);
+    vi.spyOn(console, "log").mockImplementation(() => undefined);
+    const command = createCheckCommand({
+      resolveProject: () => PROJECT,
+      runPipeline,
+      withMeta: (value) => value,
+    });
+
+    await runCommand(command, {
+      rawArgs: ["--json", "--layout", "proseCoverageFloor=0.05"],
+    });
+
+    expect(runPipeline).toHaveBeenCalledWith(
+      PROJECT,
+      expect.objectContaining({
+        layout: { proseCoverageFloor: 0.05 },
+      }),
+    );
+  });
+
+  it("forwards layout options into driver.collectLayout", async () => {
+    const collectLayout = vi.fn(async (_time: number, _tolerance: number, _layout?: unknown) => []);
+    await runScenario(fakeDriver({ collectLayout }), { layout: { proseCoverageFloor: 0.05 } });
+    expect(collectLayout).toHaveBeenCalled();
+    expect(collectLayout).toHaveBeenCalledWith(expect.any(Number), expect.any(Number), {
+      proseCoverageFloor: 0.05,
+    });
   });
 });