phase: 01_keyboard_kiosk_control

**Phase 01 final verification pass — complete, 100% green** - Verified all 4 tasks done (files in `complete/`); implementation review: key router in `watch.js`, share-page router, CSS focus/selection affordances, `?` overlay, pointer-free E2E suite — all sound. - Gates: `ruff check` + `ruff format --check` ✅ · `pyright` 0 errors ✅ · `uv run pytest` → 223 passed, 2 skipped (realdisplay), 1 pre-existing FastAPI deprecation warning · `MIRROR_REALDISPLAY=1 pytest -m realdisplay` → 2 passed ✅ · `pytest -m e2e` → 51 passed (incl. `test_keyboard_wall.py`, which a meta-test keeps pointer-free) · `node --check` on all static JS ✅. - Completion criteria: all 6 ✅ (j/k+Enter, f/g/n/p/1–9/m/?/Esc keyboard-only E2E; no hover-only controls via CSS guard + focus-ring E2E; `#name` text-safe; e2e/realdisplay green; key map documented in README "Kiosk client" and `docs/kiosk-silverblue.md`). - README fixed: added missing env vars `MIRROR_MAX_BITRATE`, `MIRROR_PING_INTERVAL`, `DEBUGPY_WAIT` to the config table; added the one-time `rpm-ostree` layering note before the kiosk install snippet. - AGENTS.md fixed: removed stale "roadmap is intentionally empty" parenthetical (3 phases pending); coverage ~94% → ~95%. No content added. - **Unresolved, needs your call:** README/SECURITY.md say `mirror.reeseapps.com`; `docs/kiosk-silverblue.md` (reference-client naming table with real IPs) says `mirror.reeselink.com`. I couldn't verify which is the live deployment domain, so I changed neither — say the word and I'll unify. - Next pending phase: `02_sharp_capture`.
2026-11-01 20:53:28 -05:00
parent f3de5b70ff
commit 1e816da5a8
39 changed files with 1726 additions and 31 deletions
@@ -0,0 +1,902 @@
+"""End-to-end: the keyboard is a complete control surface for mirror.
+
+Phase 01, tasks 01-04: one focus-aware keydown router plus a keyboard cursor
+over the tiles (j/k/Up/Down, Esc), the wall commands (Enter/f, g, n/p, 1-9,
+m), the ``?`` help overlay, the focus-visible affordances — no control is
+reachable *only* by hover — and the /mirror keys (s, x, Esc). Every command
+here is driven with ``page.keyboard.press()`` and asserted on the DOM state
+the key changes — ``data-selected``, focus, the ``staged`` class, the
+``muted`` flag, computed styles — never on whether a handler "ran".
+
+The suite is pointer-free: a test that reaches for the pointer proves nothing
+about a kiosk. The meta-test at the bottom enforces that on this file
+itself, so the guarantee cannot rot.
+"""
+
+from __future__ import annotations
+
+import os
+import re
+import socket
+import subprocess
+import sys
+import time
+from pathlib import Path
+
+import pytest
+from playwright.sync_api import expect
+
+from .conftest import start_sharing
+
+pytestmark = [pytest.mark.e2e, pytest.mark.timeout(180)]
+
+
+@pytest.fixture
+def device(base_url, browser, request):
+    """Open a page as its own device (isolated context, fresh peer id).
+
+    Uncaught page errors and console errors are captured from the first line of
+    the test and surfaced through the ``errors == []`` assertion
+    (AGENTS.md §8: print pageerror/console from the first line of the test).
+    """
+    opened = []
+
+    def _open(path: str = "/", errors: list | None = None):
+        context = browser.new_context(viewport={"width": 1100, "height": 720})
+        opened.append(context)
+        request.addfinalizer(context.close)
+        page = context.new_page()
+        if errors is not None:
+            page.on("pageerror", lambda error: errors.append(f"pageerror: {error}"))
+            page.on(
+                "console",
+                lambda message: (
+                    errors.append(f"console: {message.text}") if message.type == "error" else None
+                ),
+            )
+        page.goto(f"{base_url}{path}", wait_until="domcontentloaded")
+        expect(page.locator("#net")).to_have_attribute("data-state", "online", timeout=10_000)
+        return page
+
+    return _open
+
+
+def _non_loopback_ipv4() -> str | None:
+    """The address a *neighbour* would use to reach this machine, or None.
+
+    A UDP connect sends no packet; it only resolves the default route, which
+    is exactly the interface a LAN device would see.
+    """
+    with socket.socket(socket.AF_INET, socket.SOCK_DGRAM) as probe:
+        try:
+            probe.connect(("8.8.8.8", 80))
+        except OSError:
+            return None
+        address = probe.getsockname()[0]
+    return address if address != "127.0.0.1" else None
+
+
+@pytest.fixture
+def insecure_base_url():
+    """A `mirror serve` on a plain-HTTP non-localhost address.
+
+    That is a non-secure context: the browser hides `navigator.mediaDevices`
+    entirely — the exact trap /mirror documents for a bare `mirror serve` on a
+    LAN IP (README, docs/kiosk-silverblue.md "One trap worth knowing").
+    """
+    host = _non_loopback_ipv4()
+    if host is None:
+        pytest.skip("no non-loopback interface: the non-secure-context trap is untestable here")
+    import httpx
+
+    from .conftest import _free_port
+
+    port = _free_port()
+    process = subprocess.Popen(
+        [
+            sys.executable,
+            "-m",
+            "mirror",
+            "serve",
+            "--host",
+            "0.0.0.0",
+            "--port",
+            str(port),
+            "--log-level",
+            "warning",
+        ],
+        cwd=Path(__file__).resolve().parents[2],
+        stdout=subprocess.PIPE,
+        stderr=subprocess.STDOUT,
+        text=True,
+        env={
+            **os.environ,
+            "MIRROR_ICE_SERVERS": "",
+            "PYTHONUNBUFFERED": "1",
+            "DEBUGPY": "0",
+        },
+    )
+    url = f"http://{host}:{port}"
+    last_error: Exception | None = None
+    deadline = time.time() + 25
+    while time.time() < deadline:
+        if process.poll() is not None:
+            output = process.stdout.read() if process.stdout else ""
+            raise RuntimeError(f"mirror serve exited early ({process.returncode}):\n{output}")
+        try:
+            if httpx.get(f"{url}/healthz", timeout=1.0).status_code == 200:
+                break
+        except Exception as exc:  # still booting
+            last_error = exc
+        time.sleep(0.15)
+    else:
+        process.terminate()
+        raise RuntimeError(f"mirror serve never came up: {last_error}")
+    yield url
+    process.terminate()
+    try:
+        process.wait(timeout=5)
+    except subprocess.TimeoutExpired:  # pragma: no cover
+        process.kill()
+
+
+def tile_ids(page) -> list[str]:
+    return page.locator(".tile").evaluate_all("els => els.map(e => e.dataset.stream)")
+
+
+def selected_id(page) -> str | None:
+    return page.evaluate(
+        "() => { const el = document.querySelector('.tile[data-selected]');"
+        " return el ? el.dataset.stream : null; }"
+    )
+
+
+def focus_follows_selection(page) -> bool:
+    return page.evaluate(
+        "() => { const el = document.querySelector('.tile[data-selected]');"
+        " return el !== null && document.activeElement === el; }"
+    )
+
+
+class TestKeyboardCursor:
+    def _two_mirror_wall(self, device, errors: list) -> tuple:
+        for _ in range(2):
+            start_sharing(device("/mirror", errors))
+        viewer = device("/watch", errors)
+        expect(viewer.locator(".tile")).to_have_count(2, timeout=15_000)
+        return viewer, tile_ids(viewer)
+
+    def test_j_selects_the_first_tile_and_focus_follows(self, device):
+        errors: list = []
+        viewer, ids = self._two_mirror_wall(device, errors)
+
+        viewer.keyboard.press("j")
+        assert selected_id(viewer) == ids[0]
+        assert focus_follows_selection(viewer), "focus must follow the selection"
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_j_and_k_wrap_at_the_ends(self, device):
+        errors: list = []
+        viewer, ids = self._two_mirror_wall(device, errors)
+
+        viewer.keyboard.press("j")
+        assert selected_id(viewer) == ids[0]
+        # k from the first wraps to the last.
+        viewer.keyboard.press("k")
+        assert selected_id(viewer) == ids[1]
+        # j from the last wraps back to the first.
+        viewer.keyboard.press("j")
+        assert selected_id(viewer) == ids[0]
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_arrow_keys_drive_the_same_cursor(self, device):
+        errors: list = []
+        viewer, ids = self._two_mirror_wall(device, errors)
+
+        viewer.keyboard.press("ArrowDown")
+        assert selected_id(viewer) == ids[0]
+        viewer.keyboard.press("ArrowDown")
+        assert selected_id(viewer) == ids[1]
+        viewer.keyboard.press("ArrowUp")
+        assert selected_id(viewer) == ids[0]
+        # The cursor must not fight real scrolling: the router suppresses the
+        # arrow's default while it handles the key.
+        viewer.keyboard.press("ArrowUp")
+        assert selected_id(viewer) == ids[1]
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_ctrl_chords_never_run_a_command(self, device):
+        errors: list = []
+        viewer, ids = self._two_mirror_wall(device, errors)
+
+        viewer.keyboard.press("j")
+        assert selected_id(viewer) == ids[0]
+        # Synthesised ctrlKey: true — the browser's chords are never ours.
+        viewer.keyboard.press("Control+j")
+        assert selected_id(viewer) == ids[0]
+        viewer.keyboard.press("Control+k")
+        assert selected_id(viewer) == ids[0]
+        viewer.keyboard.press("Control+ArrowDown")
+        assert selected_id(viewer) == ids[0]
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_shifted_letters_drive_the_same_commands(self, device):
+        errors: list = []
+        viewer, ids = self._two_mirror_wall(device, errors)
+
+        # Keys are matched case-insensitively: a caps-locked kiosk keyboard, or
+        # a remote hand holding Shift, must work exactly the same.
+        viewer.keyboard.press("Shift+J")
+        assert selected_id(viewer) == ids[0]
+        # Shift+F stages through the same command as f.
+        viewer.keyboard.press("Shift+F")
+        expect(viewer.locator("body")).to_have_class(re.compile("staged"), timeout=5_000)
+        assert viewer.locator("#watch-stage .tile").get_attribute("data-stream") == ids[0]
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+
+class TestEscape:
+    def test_escape_leaves_the_stage(self, device):
+        errors: list = []
+        start_sharing(device("/mirror", errors))
+        viewer = device("/watch", errors)
+        expect(viewer.locator(".tile")).to_have_count(1, timeout=15_000)
+
+        # Staged the way the kiosk stages — select, then Enter — because this
+        # suite is pointer-free; Esc is what the kiosk uses to leave the stage.
+        viewer.keyboard.press("j")
+        viewer.keyboard.press("Enter")
+        expect(viewer.locator("body")).to_have_class(re.compile("staged"), timeout=5_000)
+
+        viewer.keyboard.press("Escape")
+        expect(viewer.locator("body")).not_to_have_class(re.compile("staged"), timeout=5_000)
+        # Leaving the stage must not have disturbed the stream.
+        expect(viewer.locator(".tile[data-state='live']")).to_have_count(1, timeout=20_000)
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_escape_without_a_stage_is_a_noop(self, device):
+        errors: list = []
+        start_sharing(device("/mirror", errors))
+        viewer = device("/watch", errors)
+        expect(viewer.locator(".tile")).to_have_count(1, timeout=15_000)
+
+        viewer.keyboard.press("Escape")
+        expect(viewer.locator("body")).not_to_have_class(re.compile("staged"))
+        expect(viewer.locator(".tile")).to_have_count(1)
+        expect(viewer.locator(".tile[data-state='live']")).to_have_count(1, timeout=20_000)
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+
+class TestWallCommands:
+    """Task 02: Enter/f, g, n/p, 1-9, m on /watch.
+
+    Every command is driven with ``page.keyboard.press()`` and asserted on the
+    DOM state the key changes — the staged tile id, the ``staged`` class, the
+    video's ``muted`` flag, the ``#toast`` — never on whether a handler "ran".
+    """
+
+    def _two_mirror_wall(self, device, errors: list) -> tuple:
+        for _ in range(2):
+            start_sharing(device("/mirror", errors))
+        viewer = device("/watch", errors)
+        expect(viewer.locator(".tile")).to_have_count(2, timeout=15_000)
+        return viewer, tile_ids(viewer)
+
+    def test_enter_stages_the_selected_mirror(self, device):
+        errors: list = []
+        viewer, ids = self._two_mirror_wall(device, errors)
+
+        viewer.keyboard.press("j")
+        viewer.keyboard.press("Enter")
+        expect(viewer.locator("body")).to_have_class(re.compile("staged"), timeout=5_000)
+        expect(viewer.locator("#watch-stage .tile")).to_have_count(1)
+        assert viewer.locator("#watch-stage .tile").get_attribute("data-stream") == ids[0]
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_enter_with_nothing_selected_stages_the_first_tile(self, device):
+        errors: list = []
+        viewer, ids = self._two_mirror_wall(device, errors)
+
+        viewer.keyboard.press("Enter")
+        expect(viewer.locator("body")).to_have_class(re.compile("staged"), timeout=5_000)
+        expect(viewer.locator("#watch-stage .tile")).to_have_count(1)
+        assert viewer.locator("#watch-stage .tile").get_attribute("data-stream") == ids[0]
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_f_stages_when_unstaged_and_holds_the_stage_when_staged(self, device):
+        errors: list = []
+        viewer, ids = self._two_mirror_wall(device, errors)
+
+        # Unstaged: `f` stages like Enter (first tile, nothing selected).
+        viewer.keyboard.press("f")
+        expect(viewer.locator("body")).to_have_class(re.compile("staged"), timeout=5_000)
+        assert viewer.locator("#watch-stage .tile").get_attribute("data-stream") == ids[0]
+
+        # Staged: `f` re-requests fullscreen. A kiosk's window manager can drop
+        # the window out of fullscreen without the page noticing, so the
+        # command must never tear the stage down — headless or not.
+        viewer.keyboard.press("f")
+        expect(viewer.locator("body")).to_have_class(re.compile("staged"), timeout=5_000)
+        expect(viewer.locator("#watch-stage .tile")).to_have_count(1)
+        assert viewer.locator("#watch-stage .tile").get_attribute("data-stream") == ids[0]
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_g_returns_to_the_wall(self, device):
+        errors: list = []
+        viewer, _ = self._two_mirror_wall(device, errors)
+
+        viewer.keyboard.press("j")
+        viewer.keyboard.press("Enter")
+        expect(viewer.locator("body")).to_have_class(re.compile("staged"), timeout=5_000)
+
+        viewer.keyboard.press("g")
+        expect(viewer.locator("body")).not_to_have_class(re.compile("staged"), timeout=5_000)
+        expect(viewer.locator("#watch-stage .tile")).to_have_count(0)
+        expect(viewer.locator(".tile")).to_have_count(2)
+
+        # g on an already-unstaged wall is a silent no-op: the wall *is* the
+        # visible result "back to the wall".
+        viewer.keyboard.press("g")
+        expect(viewer.locator(".tile")).to_have_count(2)
+        expect(viewer.locator("#toast")).not_to_be_visible()
+
+        # Leaving the stage must not have disturbed the streams.
+        expect(viewer.locator(".tile[data-state='live']")).to_have_count(2, timeout=20_000)
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_n_and_p_step_between_mirrors_without_killing_the_peer(self, device):
+        errors: list = []
+        viewer, ids = self._two_mirror_wall(device, errors)
+        a, b = ids[0], ids[1]
+        expect(viewer.locator(".tile[data-state='live']")).to_have_count(2, timeout=30_000)
+
+        # Stage A by keyboard.
+        viewer.keyboard.press("j")
+        viewer.keyboard.press("Enter")
+        expect(viewer.locator("#watch-stage .tile")).to_have_count(1, timeout=5_000)
+        assert viewer.locator("#watch-stage .tile").get_attribute("data-stream") == a
+
+        # Mark A's <video> node: staging B must *move* it back to the grid,
+        # never recreate it — the element moves, srcObject is never reassigned.
+        assert viewer.evaluate(
+            """(id) => {
+              const el = document.querySelector('#watch-stage video');
+              el.dataset.e2e = "same-node";
+              return el.srcObject !== null;
+            }""",
+            a,
+        ), "A's video must hold a live stream before the switch"
+
+        viewer.keyboard.press("n")
+        expect(viewer.locator("#watch-stage .tile")).to_have_count(1, timeout=5_000)
+        assert viewer.locator("#watch-stage .tile").get_attribute("data-stream") == b
+        assert viewer.evaluate(
+            """(id) => {
+              const el = document.querySelector(`.tile[data-stream="${id}"] video`);
+              return el !== null && el.dataset.e2e === "same-node" && el.srcObject !== null;
+            }""",
+            a,
+        ), "A's <video> must be the same node, still holding its stream"
+
+        # p wraps back to A — and the stepping must not have killed either mirror.
+        viewer.keyboard.press("p")
+        expect(viewer.locator("#watch-stage .tile")).to_have_count(1, timeout=5_000)
+        assert viewer.locator("#watch-stage .tile").get_attribute("data-stream") == a
+
+        expect(viewer.locator(".tile[data-state='live']")).to_have_count(2, timeout=20_000)
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_digit_jump_stages_the_nth_mirror(self, device):
+        errors: list = []
+        viewer, ids = self._two_mirror_wall(device, errors)
+
+        viewer.keyboard.press("2")
+        expect(viewer.locator("body")).to_have_class(re.compile("staged"), timeout=5_000)
+        expect(viewer.locator("#watch-stage .tile")).to_have_count(1)
+        assert viewer.locator("#watch-stage .tile").get_attribute("data-stream") == ids[1]
+
+        # 1 takes the first mirror back on stage; stage() unstages the other.
+        viewer.keyboard.press("1")
+        expect(viewer.locator("#watch-stage .tile")).to_have_count(1, timeout=5_000)
+        assert viewer.locator("#watch-stage .tile").get_attribute("data-stream") == ids[0]
+
+        # The wall survives the jump: both mirrors still live.
+        expect(viewer.locator(".tile[data-state='live']")).to_have_count(2, timeout=20_000)
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_m_flips_the_staged_videos_muted_flag(self, device):
+        errors: list = []
+        viewer, _ = self._two_mirror_wall(device, errors)
+
+        viewer.keyboard.press("j")
+        viewer.keyboard.press("Enter")
+        expect(viewer.locator("#watch-stage video")).to_have_count(1, timeout=5_000)
+
+        before = viewer.evaluate("() => document.querySelector('#watch-stage video').muted")
+        viewer.keyboard.press("m")
+        after = viewer.evaluate("() => document.querySelector('#watch-stage video').muted")
+        assert after == (not before), f"m must flip muted ({before} -> {after})"
+
+        # The tile's audio button tracks the same state through setMuted.
+        assert (
+            viewer.locator("#watch-stage .audio").get_attribute("aria-pressed")
+            == str(not after).lower()
+        ), "aria-pressed must follow the muted flag"
+
+        # And back again.
+        viewer.keyboard.press("m")
+        again = viewer.evaluate("() => document.querySelector('#watch-stage video').muted")
+        assert again == before, f"m must flip back ({after} -> {again})"
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_missing_mirror_number_toasts_instead_of_silence(self, device):
+        errors: list = []
+        sharer = device("/mirror", errors)
+        start_sharing(sharer)
+        viewer = device("/watch", errors)
+        expect(viewer.locator(".tile")).to_have_count(1, timeout=15_000)
+
+        viewer.keyboard.press("5")
+
+        # The wall is unchanged…
+        expect(viewer.locator("body")).not_to_have_class(re.compile("staged"))
+        expect(viewer.locator(".tile")).to_have_count(1)
+        # …and the no-op says why — a silent no-op is undiagnosable from a kiosk.
+        expect(viewer.locator("#toast")).to_be_visible()
+        expect(viewer.locator("#toast")).to_contain_text("no mirror 5")
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_commands_on_an_empty_wall_toast_the_reason(self, device):
+        errors: list = []
+        viewer = device("/watch", errors)
+        expect(viewer.locator("#empty")).to_be_visible()
+
+        viewer.keyboard.press("Enter")
+        expect(viewer.locator("body")).not_to_have_class(re.compile("staged"))
+        expect(viewer.locator("#toast")).to_be_visible()
+        expect(viewer.locator("#toast")).to_contain_text("no mirrors to stage")
+
+        viewer.keyboard.press("n")
+        expect(viewer.locator("body")).not_to_have_class(re.compile("staged"))
+        expect(viewer.locator("#toast")).to_contain_text("no mirrors to switch to")
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+
+class TestFocusVisibleControls:
+    """Task 03: no control is reachable *only* by hover.
+
+    Everything here is keyboard-only: ``Tab`` moves focus, and the assertions
+    are on what the kiosk *sees* — computed opacity, the focus ring,
+    ``data-selected`` — never on whether a handler "ran". No test in this class
+    drives the pointer.
+    """
+
+    def _one_mirror_wall(self, device, errors: list):
+        start_sharing(device("/mirror", errors))
+        viewer = device("/watch", errors)
+        expect(viewer.locator(".tile")).to_have_count(1, timeout=15_000)
+        return viewer
+
+    def _two_mirror_wall(self, device, errors: list) -> tuple:
+        for _ in range(2):
+            start_sharing(device("/mirror", errors))
+        viewer = device("/watch", errors)
+        expect(viewer.locator(".tile")).to_have_count(2, timeout=15_000)
+        return viewer, tile_ids(viewer)
+
+    @staticmethod
+    def _tab_to_a_tile(viewer, attempts: int = 12) -> str | None:
+        """Tab from the top of the document until focus lands on a tile."""
+        for _ in range(attempts):
+            viewer.keyboard.press("Tab")
+            tile = viewer.evaluate(
+                "() => { const el = document.activeElement;"
+                " return el && el.classList.contains('tile') ? el.dataset.stream : null; }"
+            )
+            if tile:
+                return tile
+        return None
+
+    def test_tab_focus_reveals_the_tile_controls(self, device):
+        errors: list = []
+        viewer = self._one_mirror_wall(device, errors)
+
+        assert self._tab_to_a_tile(viewer), "Tab must reach the tile without a pointer"
+
+        # The opacity transition is 150 ms; wait for the settled value.
+        viewer.wait_for_function(
+            "() => { const el = document.activeElement;"
+            " return el && el.classList.contains('tile')"
+            " && getComputedStyle(el.querySelector('.actions')).opacity === '1'; }",
+            timeout=5_000,
+        )
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_keyboard_focus_draws_a_visible_ring(self, device, tmp_path):
+        errors: list = []
+        viewer = self._one_mirror_wall(device, errors)
+
+        assert self._tab_to_a_tile(viewer)
+
+        ring = viewer.evaluate(
+            "() => { const s = getComputedStyle(document.activeElement);"
+            " return { width: s.outlineWidth, style: s.outlineStyle, color: s.outlineColor }; }"
+        )
+        assert ring["style"] == "solid", f"the focus ring must be visible: {ring}"
+        assert ring["width"] == "2px", ring
+        assert ring["color"] != "rgba(0, 0, 0, 0)", f"the ring must not be transparent: {ring}"
+
+        # Screenshot artifact: a kiosk is debugged from another machine, so a
+        # focused tile must be legible in a still frame.
+        shot = tmp_path / "focused_tile.png"
+        viewer.screenshot(path=str(shot))
+        assert shot.stat().st_size > 0
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_tab_focus_moves_the_selection_with_it(self, device):
+        errors: list = []
+        viewer, ids = self._two_mirror_wall(device, errors)
+
+        seen: list[str] = []
+        for _ in range(16):
+            viewer.keyboard.press("Tab")
+            on_tile = viewer.evaluate(
+                "() => document.activeElement !== null"
+                " && document.activeElement.classList.contains('tile')"
+            )
+            if on_tile:
+                seen.append(selected_id(viewer))
+                # While a tile itself holds focus, data-selected must be that tile.
+                assert viewer.evaluate(
+                    "() => document.activeElement === document.querySelector"
+                    "('.tile[data-selected]')"
+                ), "the selected tile must be the focused tile"
+            if len(seen) == 2:
+                break
+
+        assert seen == ids, f"Tab must walk the grid in order {ids}; walked {seen}"
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_tab_to_a_tile_button_is_not_stolen_back_to_the_tile(self, device):
+        errors: list = []
+        viewer = self._one_mirror_wall(device, errors)
+
+        assert self._tab_to_a_tile(viewer)
+        # The selected tile carries its controls, so the next Tab reaches a
+        # control *inside* the tile — and must stay there: the focusin
+        # handler must not pull focus back off the control the operator is on.
+        viewer.keyboard.press("Tab")
+        assert viewer.evaluate(
+            "() => document.activeElement !== null"
+            " && document.activeElement.closest('.actions') !== null"
+        ), "Tab must be able to land on a control inside the tile"
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_the_wall_stays_quiet_until_something_is_focused(self, device):
+        errors: list = []
+        viewer = self._one_mirror_wall(device, errors)
+
+        # Nothing hovered, focused or selected: the controls stay hidden, so a
+        # shared display keeps its quiet look.
+        opacity = viewer.evaluate(
+            "() => getComputedStyle(document.querySelector('.tile .actions')).opacity"
+        )
+        assert opacity == "0", (
+            f"the wall must stay quiet until a tile is focused or selected (got {opacity})"
+        )
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_focus_moves_to_the_stage_and_back_with_g(self, device):
+        errors: list = []
+        viewer = self._one_mirror_wall(device, errors)
+
+        viewer.keyboard.press("Enter")
+        expect(viewer.locator("body")).to_have_class(re.compile("staged"), timeout=5_000)
+        assert viewer.evaluate(
+            "() => document.activeElement !== null"
+            " && document.activeElement.parentElement.id === 'watch-stage'"
+        ), "staging must hand focus to the staged tile"
+
+        # The staged caption is legible while the tile holds focus (the
+        # opacity transition is 200 ms; wait for the settled value).
+        viewer.wait_for_function(
+            "() => document.activeElement !== null"
+            " && getComputedStyle(document.activeElement.querySelector('.cap')).opacity === '1'",
+            timeout=5_000,
+        )
+
+        # m still works with focus sitting on the stage.
+        before = viewer.evaluate("() => document.querySelector('#watch-stage video').muted")
+        viewer.keyboard.press("m")
+        after = viewer.evaluate("() => document.querySelector('#watch-stage video').muted")
+        assert after == (not before), f"m must flip muted on the staged tile ({before} -> {after})"
+
+        # g returns to the wall and hands focus back to the tile's grid slot.
+        # The hand-back is deferred until the fullscreen exit has settled
+        # (the exit would otherwise drop the focus back to <body>), so wait
+        # for it rather than asserting on the keypress alone.
+        viewer.keyboard.press("g")
+        expect(viewer.locator("body")).not_to_have_class(re.compile("staged"), timeout=5_000)
+        viewer.wait_for_function(
+            "() => { const el = document.activeElement;"
+            " return el !== null && el.classList.contains('tile')"
+            " && el.parentElement.id === 'grid'"
+            " && el === document.querySelector('.tile[data-selected]'); }",
+            timeout=5_000,
+        )
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_escape_after_staging_returns_focus_to_the_grid(self, device):
+        errors: list = []
+        viewer = self._one_mirror_wall(device, errors)
+
+        viewer.keyboard.press("Enter")
+        expect(viewer.locator("body")).to_have_class(re.compile("staged"), timeout=5_000)
+
+        viewer.keyboard.press("Escape")
+        expect(viewer.locator("body")).not_to_have_class(re.compile("staged"), timeout=5_000)
+        viewer.wait_for_function(
+            "() => { const el = document.activeElement;"
+            " return el !== null && el.classList.contains('tile')"
+            " && el.parentElement.id === 'grid'; }",
+            timeout=5_000,
+        )
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+
+class TestHelpOverlay:
+    """Task 04: `?` shows the key list; `?`/`Esc` close it; focus never moves.
+
+    The overlay is the element ``watch.js`` reaches for (``#wall-help``) and it
+    exists in ``watch.html`` (the element-existence guard enforces the pairing)
+    — asserted here on the DOM state, as always, never on whether a handler
+    "ran".
+    """
+
+    def _one_mirror_wall(self, device, errors: list):
+        start_sharing(device("/mirror", errors))
+        viewer = device("/watch", errors)
+        expect(viewer.locator(".tile")).to_have_count(1, timeout=15_000)
+        return viewer
+
+    def test_question_mark_opens_the_key_list(self, device):
+        errors: list = []
+        viewer = self._one_mirror_wall(device, errors)
+        expect(viewer.locator("#wall-help")).to_be_hidden()
+
+        viewer.keyboard.press("?")
+        expect(viewer.locator("#wall-help")).to_be_visible()
+        # The list is the locked key map from 00_phase.md — a kiosk operator
+        # can read back every command the wall accepts.
+        for text in (
+            "next mirror",
+            "previous mirror",
+            "Stage the selected mirror fullscreen",
+            "Back to the wall",
+            "Stage the next / previous mirror",
+            "Stage the Nth mirror",
+            "Mute / unmute the staged mirror",
+            "Close this list, then leave the stage",
+        ):
+            expect(viewer.locator("#wall-help")).to_contain_text(text)
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_question_mark_closes_the_key_list(self, device):
+        errors: list = []
+        viewer = self._one_mirror_wall(device, errors)
+
+        viewer.keyboard.press("?")
+        expect(viewer.locator("#wall-help")).to_be_visible()
+
+        viewer.keyboard.press("?")
+        expect(viewer.locator("#wall-help")).to_be_hidden()
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_the_list_says_how_to_close_it(self, device):
+        errors: list = []
+        viewer = self._one_mirror_wall(device, errors)
+
+        viewer.keyboard.press("?")
+        expect(viewer.locator("#wall-help .hint")).to_contain_text("to close this list")
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_escape_closes_the_overlay_before_it_unstages(self, device):
+        errors: list = []
+        viewer = self._one_mirror_wall(device, errors)
+
+        viewer.keyboard.press("j")
+        viewer.keyboard.press("Enter")
+        expect(viewer.locator("body")).to_have_class(re.compile("staged"), timeout=5_000)
+
+        # ? over the stage: the overlay sits above the stage (z-index 70 over
+        # 50), so it is readable with a mirror on stage.
+        viewer.keyboard.press("?")
+        expect(viewer.locator("#wall-help")).to_be_visible()
+
+        # First Esc: the overlay closes, the stage stays.
+        viewer.keyboard.press("Escape")
+        expect(viewer.locator("#wall-help")).to_be_hidden()
+        expect(viewer.locator("body")).to_have_class(re.compile("staged"))
+
+        # Second Esc: the stage goes.
+        viewer.keyboard.press("Escape")
+        expect(viewer.locator("body")).not_to_have_class(re.compile("staged"), timeout=5_000)
+        expect(viewer.locator("#watch-stage .tile")).to_have_count(0)
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_focus_stays_on_the_selected_tile_through_the_overlay(self, device):
+        errors: list = []
+        viewer = self._one_mirror_wall(device, errors)
+
+        viewer.keyboard.press("j")
+        assert viewer.evaluate(
+            "() => document.activeElement !== null"
+            " && document.activeElement.classList.contains('tile')"
+        ), "the selected tile must hold focus before the overlay"
+
+        for key in ("?", "?", "Escape"):
+            viewer.keyboard.press(key)
+            assert viewer.evaluate(
+                "() => document.activeElement !== null"
+                " && document.activeElement.classList.contains('tile')"
+            ), f"focus must stay on the tile after {key!r}"
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+
+class TestSharePageKeys:
+    """Task 04: `s`/`x`/`Esc` on /mirror, and the no-silent-failure rule.
+
+    The sharer here is driven by the keyboard exactly as a kiosk operator would
+    drive it; ``start_sharing`` (a pointer helper on conftest) is used only to
+    stand up *wall* mirrors, never to start a share under test.
+    """
+
+    def test_s_starts_a_share_and_x_stops_it(self, device):
+        errors: list = []
+        page = device("/mirror", errors)
+        expect(page.locator("body")).to_have_attribute("data-live", "off")
+
+        # A keydown is a user activation, so the fake UI approves the OS picker
+        # and the real capture -> preview path runs.
+        page.keyboard.press("s")
+        expect(page.locator("body")).to_have_attribute("data-live", "on", timeout=15_000)
+
+        page.keyboard.press("x")
+        expect(page.locator("body")).to_have_attribute("data-live", "off", timeout=10_000)
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_s_while_sharing_toasts_instead_of_opening_a_second_picker(self, device):
+        errors: list = []
+        page = device("/mirror", errors)
+
+        page.keyboard.press("s")
+        expect(page.locator("body")).to_have_attribute("data-live", "on", timeout=15_000)
+
+        page.keyboard.press("s")
+        expect(page.locator("#toast")).to_be_visible()
+        expect(page.locator("#toast")).to_contain_text("already sharing")
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_x_while_idle_toasts_instead_of_silence(self, device):
+        errors: list = []
+        page = device("/mirror", errors)
+
+        page.keyboard.press("x")
+        expect(page.locator("#toast")).to_be_visible()
+        expect(page.locator("#toast")).to_contain_text("not sharing")
+        expect(page.locator("body")).to_have_attribute("data-live", "off")
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_s_and_x_type_text_in_the_name_field_instead(self, device):
+        errors: list = []
+        page = device("/mirror", errors)
+
+        page.locator("#name").focus()
+        page.keyboard.press("s")
+        expect(page.locator("#name")).to_have_value("s")
+        page.keyboard.press("x")
+        expect(page.locator("#name")).to_have_value("sx")
+        # A key in the display-name field is text, not a command: no share
+        # started, no share stopped, no picker.
+        expect(page.locator("body")).to_have_attribute("data-live", "off")
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_ctrl_chords_never_share(self, device):
+        errors: list = []
+        page = device("/mirror", errors)
+
+        page.keyboard.press("Control+s")
+        expect(page.locator("body")).to_have_attribute("data-live", "off")
+        expect(page.locator("#toast")).not_to_be_visible()
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+
+    def test_s_says_why_when_capturing_is_unavailable(self, browser, insecure_base_url):
+        """The no-silent-failure path: `#start` disabled must not make `s` die quietly.
+
+        A plain-HTTP non-localhost origin is a non-secure context, so the
+        browser hides mediaDevices entirely and the page disables `#start` on
+        load. Pressing `s` routes through the button's own path (start() re-
+        checks captureSupport() and re-shows the notice) instead of failing
+        silently.
+        """
+        errors: list = []
+        context = browser.new_context(viewport={"width": 1100, "height": 720})
+        page = context.new_page()
+        page.on("pageerror", lambda error: errors.append(f"pageerror: {error}"))
+        page.on(
+            "console",
+            lambda message: (
+                errors.append(f"console: {message.text}") if message.type == "error" else None
+            ),
+        )
+        page.goto(f"{insecure_base_url}/mirror", wait_until="domcontentloaded")
+
+        # The premise: this really is the trap — the browser has hidden the
+        # media API, exactly as it does on a bare-LAN-IP deployment.
+        assert page.evaluate("() => window.isSecureContext") is False
+        assert page.evaluate("() => navigator.mediaDevices === undefined")
+        expect(page.locator("#net")).to_have_attribute("data-state", "online", timeout=10_000)
+
+        # The page says so and disables the button on load…
+        expect(page.locator("#notice")).to_be_visible()
+        expect(page.locator("#notice")).to_contain_text("secure context")
+        expect(page.locator("#start")).to_be_disabled()
+
+        # …and `s` does not fail silently: the notice stays up, nothing starts.
+        page.keyboard.press("s")
+        expect(page.locator("#notice")).to_be_visible()
+        expect(page.locator("#notice")).to_contain_text("secure context")
+        expect(page.locator("body")).to_have_attribute("data-live", "off")
+
+        assert errors == [], f"uncaught browser errors: {errors}"
+        context.close()
+
+
+class TestSuiteIsPointerFree:
+    """The kiosk guarantee, enforced on the file itself.
+
+    A test that reaches for the pointer proves nothing about a kiosk. The
+    guarantee lives in the code, not in reviewer attention, so this meta-test
+    bans the pointer calls on this file and fails the suite the moment one
+    slips back in.
+    """
+
+    def test_the_suite_never_reaches_for_the_pointer(self):
+        source = Path(__file__).read_text()
+        # Built from parts so this very assertion does not contain the banned
+        # literals (a plain string here would trip the check on itself).
+        assert ("cli" + "ck(") not in source, "a pointer call slipped into the keyboard suite"
+        assert ("hover" + "(") not in source, "a pointer call slipped into the keyboard suite"