orisys-app/apps/studio/tools/ui_check.py

#!/usr/bin/env python3
"""Dependency-free smoke run for the studio UI.

``pytest`` is the canonical runner (``apps/studio/tests``), but this script
needs nothing beyond the app's own runtime dependencies, so it can be used in
minimal environments:

    python tools/ui_check.py

It builds the real main window offscreen and asserts the layout, theming and
status-feedback invariants that the UI work depends on.
"""

from __future__ import annotations

import os
import sys
import threading
import time
from pathlib import Path
APP_ROOT = Path(__file__).resolve().parents[1]
REPO_ROOT = APP_ROOT.parents[1]
for _path in (APP_ROOT / "src", REPO_ROOT / "shared" / "src"):
    if _path.is_dir() and str(_path) not in sys.path:
        sys.path.insert(0, str(_path))

os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
if sys.platform == "win32" and "QT_QPA_FONTDIR" not in os.environ:
    _fonts = Path(os.environ.get("WINDIR", r"C:\Windows")) / "Fonts"
    if _fonts.is_dir():
        os.environ["QT_QPA_FONTDIR"] = str(_fonts)
os.chdir(APP_ROOT)

from orisys_app_shared.acquisition.sinks import RecordSinkMixin  # noqa: E402
from orisys_app_shared.force.filters import FilterSettings  # noqa: E402
from orisys_app_shared.record import FORCES_HEADER  # noqa: E402

FAILURES: list[str] = []
CHECKS = 0


def check(condition: bool, message: str) -> None:
    global CHECKS
    CHECKS += 1
    if not condition:
        FAILURES.append(message)


def _inside_scroll_area(widget) -> bool:
    """True when ``widget`` lives inside a QScrollArea's content."""
    from PyQt5.QtWidgets import QScrollArea

    node = widget
    while node is not None:
        if isinstance(node, QScrollArea):
            return True
        node = node.parentWidget() if hasattr(node, "parentWidget") else None
    return False


def rail_squeezed(window) -> list[str]:
    """Status-rail widgets showing less than their own text.

    The rail shares one line with the session state, so every item that states a
    fact (``摄像机 0``, ``开始记录``) must keep its full text; only the labels
    that carry a tooltip are allowed to shrink. An elided button is how a
    readable instrument turns back into a jumble.
    """
    layout = window.toolbar.layout().itemAt(0).layout()
    squeezed: list[str] = []
    for index in range(layout.count()):
        widget = layout.itemAt(index).widget()
        if widget is None or not widget.isVisible():
            continue
        if getattr(widget, "minimumSizeHint", None) is None:
            continue
        if widget.minimumSizeHint().width() <= 0:
            continue
        if widget.width() < widget.sizeHint().width() - 1:
            squeezed.append(
                f"{type(widget).__name__}"
                f"({getattr(widget, 'objectName', lambda: '')()}"
                f" {widget.width()}<{widget.sizeHint().width()})"
            )
    return squeezed


def section(name: str) -> None:
    print(f"\n== {name} ==")


#: Sequences that only appear when UTF-8 text was decoded with a single-byte
#: codepage and re-encoded. A PowerShell ``Get-Content -Raw | Set-Content``
#: round trip does that and silently mangles every non-ASCII string, which is
#: how the Chinese UI once ended up unreadable.
#:
#: Written as escapes, with no literal examples in the comments, so that this
#: guard cannot itself be corrupted by the same mistake and so that a scan of
#: the tree for these sequences stays clean.
MOJIBAKE_MARKERS = (
    "\u00c3",
    "\u00c2",
    "\u00e2\u20ac",
    "\u00e3\u20ac",
    "\u00ef\u00bf\u00bd",
)


def audit_locale_encoding() -> list[str]:
    """Locale files must be BOM-free UTF-8 and not mojibake."""
    import json

    problems: list[str] = []
    locales = APP_ROOT / "config" / "locales"
    for name in ("zh_CN", "en_US"):
        path = locales / f"{name}.json"
        if not path.is_file():
            problems.append(f"{name}.json is missing")
            continue
        raw = path.read_bytes()
        if raw.startswith(b"\xef\xbb\xbf"):
            problems.append(f"{name}.json starts with a UTF-8 BOM")
        try:
            text = raw.decode("utf-8")
        except UnicodeDecodeError as exc:
            problems.append(f"{name}.json is not valid UTF-8: {exc}")
            continue
        for marker in MOJIBAKE_MARKERS:
            if marker in text:
                problems.append(
                    f"{name}.json contains {marker!r} — written by a tool that "
                    "decoded UTF-8 with the wrong codepage"
                )
                break
        try:
            json.loads(text)
        except json.JSONDecodeError as exc:
            problems.append(f"{name}.json is not valid JSON: {exc}")
    # A corrupted zh_CN.json still parses, so check that it holds Chinese text.
    try:
        import json as _json

        zh = _json.loads((locales / "zh_CN.json").read_text(encoding="utf-8"))
        sample = zh["menu"]["theme_dark"]
        if not any("\u4e00" <= char <= "\u9fff" for char in sample):
            problems.append(f"zh_CN.menu.theme_dark has no Chinese text: {sample!r}")
    except Exception as exc:  # noqa: BLE001
        problems.append(f"could not verify the Chinese locale: {exc}")
    return problems


def _calibration_sample(index: int, *, fn_raw: float, fx_raw: float = 0.4, fy_raw: float = -0.2):
    """A sample shaped for the calibration recorder."""
    from orisys_app_shared.force.session import SessionSample

    return SessionSample(
        frame_id=index,
        t_rel_s=index / 100.0,
        fn_raw=fn_raw,
        fx_raw=fx_raw,
        fy_raw=fy_raw,
        fn_n=fn_raw / 100.0,
        fx_n=fx_raw / 100.0,
        fy_n=fy_raw / 100.0,
        valid=True,
    )


def _fake_packet(
    frame_id: int,
    *,
    valid: bool = True,
    depth=None,
    reason: str = "",
    calibrated_axes=None,
    timestamp: float | None = None,
    mono_t: float | None = None,
    shear_n: float | None = None,
    frame=None,
):
    """A packet shaped like the real worker's, for the record-channel checks.

    ``frame`` replaces the blank 8x8 image, so a synthetic recording can carry
    something visible (see ``ui_snapshot --scene replay``).
    """
    import numpy as np

    from orisys_app_shared.acquisition.sdk_worker import SdkPacket

    nan = float("nan")
    blank = np.zeros((8, 8, 3), np.uint8) if frame is None else frame
    # A single tall sample makes it easy to prove decimation keeps peaks.
    fn_raw = 99.0 if frame_id == 700 else (9.0 + frame_id * 0.01)
    return SdkPacket(
        raw_frame=blank,
        processed_frame=blank,
        timestamp=1000.0 + frame_id / 30.0 if timestamp is None else timestamp,
        mono_t=mono_t,
        fps=30.0,
        process_ms=1.0,
        normal_force=(2.0 + frame_id * 0.01) if valid else nan,
        shear_x=(0.5 if shear_n is None else shear_n) if valid else nan,
        shear_y=-0.5 if valid else nan,
        normal_force_raw=(9.0 + frame_id * 0.1) if valid else nan,
        shear_x_raw=0.4 if valid else nan,
        shear_y_raw=-0.4 if valid else nan,
        force_unit="N",
        force_calibrated=True,
        calibrated_axes=tuple(calibrated_axes or ()),
        session_id=1,
        frame_id=frame_id,
        valid=valid,
        invalid_reason=reason,
        raw_available=True,
        depth=depth,
    )


class _StuckWorker(RecordSinkMixin):
    """A worker whose device open never returns.

    Mirrors the real worker contract — including the record-channel sink API —
    so the window can be exercised against the failure mode the Stop button
    exists to survive.
    """

    def __init__(self) -> None:
        self._init_sinks()
        self._thread: threading.Thread | None = None
        self._end_reason: str | None = None
        self._latest = None
        self.thread_still_owned = False
        self.stop_blocked_for = 0.0
        #: Released by ``release()`` so daemon threads do not outlive the run.
        self._release = threading.Event()
        #: Calibration requests this worker was asked to apply.
        self.calibration_requests: list[str] = []
        #: Zeroing requests, and the confirmation callback the window installs.
        self.reset_requests = 0
        self.on_reset_applied = None
        #: Filters handed over before a session, and what the fake device reports
        #: as in effect (this stub has no ``configure``, so it reports nothing).
        self.filter_settings_value = FilterSettings()
        self.filter_state_value: dict = {}

    def set_filter_settings(self, settings) -> None:
        self.filter_settings_value = settings

    def filter_settings(self):
        return self.filter_settings_value

    def filter_state(self) -> dict:
        return dict(self.filter_state_value)

    def filters_unsupported(self) -> tuple[str, ...]:
        return ()

    def set_pending_calibration(self, path) -> None:
        self.calibration_requests.append(str(path))

    def reset(self) -> None:
        """Request a zeroing; a real device confirms it from its own thread.

        This stub confirms immediately (a fast device), so the window's event path
        — request, confirmation, recorded event — is exercised end to end.
        """
        self.reset_requests += 1
        if callable(self.on_reset_applied):
            packet = self._latest
            frame_id = int(getattr(packet, "frame_id", -1))
            mono_t = float(getattr(packet, "mono_t", 0.0) or 0.0)
            self.on_reset_applied(frame_id, mono_t, 1)

    def start(self, _source, *, config_ref=None) -> None:
        self._release.clear()
        self._thread = threading.Thread(target=self._hang, daemon=True)
        self._thread.start()

    def _hang(self) -> None:
        self._release.wait(timeout=600.0)

    def release(self) -> None:
        """Let the stuck thread finish so the process can exit cleanly."""
        self._release.set()
        if self._thread is not None:
            self._thread.join(timeout=5.0)

    def emit(self, packet) -> None:
        """Publish a packet exactly like the acquisition loop would."""
        self._latest = packet
        self._emit(packet)

    @property
    def is_running(self) -> bool:
        return self._thread is not None and self._thread.is_alive()

    @property
    def phase(self) -> str:
        return "connecting"

    def latest(self):
        return self._latest

    def consume_end_reason(self):
        reason, self._end_reason = self._end_reason, None
        return reason

    def stop(self, *, wait: bool = False) -> None:
        self._end_reason = self._end_reason or "stopped"
        started = time.perf_counter()
        if wait and self._thread is not None and self._thread.is_alive():
            self._thread.join(timeout=5.0)
        if self._thread is None or not self._thread.is_alive():
            self._thread = None
        self.thread_still_owned = self._thread is not None
        self.stop_blocked_for = time.perf_counter() - started


# --------------------------------------------------------------------------
# Palette rules
#
# These are the WCAG / colour-separation invariants the theme tokens must
# satisfy. ``tests/test_ui_smoke.py`` imports :func:`audit_palette` from here so
# both runners share one source of truth.
# --------------------------------------------------------------------------

TEXT_MIN_RATIO = 4.5
GRAPHIC_MIN_RATIO = 3.0
VIZ_MIN_HUE_GAP = 90.0
VIZ_MIN_LUMINANCE_RATIO = 1.2
RAMP_BLEND_STOPS = 2  # the low stops may merge into the canvas

TEXT_PAIRS: tuple[tuple[str, tuple[str, ...]], ...] = (
    ("text_primary", (
        "window_bg", "panel_bg", "card_bg", "toolbar_bg", "input_bg",
        "table_header_bg", "table_row_alt", "menu_bg", "button_bg",
        "table_selected", "scrollbar_bg",
    )),
    ("text_secondary", (
        "window_bg", "panel_bg", "card_bg", "toolbar_bg",
        "table_header_bg", "button_bg", "input_bg", "menu_bg",
    )),
    ("text_muted", ("window_bg", "panel_bg", "card_bg", "toolbar_bg", "input_bg")),
    ("hint_text", ("card_bg", "panel_bg", "window_bg", "input_bg")),
    ("accent_text", ("accent", "accent_hover", "danger_fill", "danger_fill_hover")),
    ("danger_text", ("danger_fill", "danger_fill_hover")),
    # The status rail lives on the toolbar background, so every semantic colour
    # it can show is audited there too — not only on the panel/card backgrounds.
    ("danger", ("card_bg", "panel_bg", "toolbar_bg")),
    ("danger_hover", ("card_bg", "panel_bg", "toolbar_bg")),
    ("warning", ("card_bg", "panel_bg", "toolbar_bg")),
    ("info", ("card_bg", "panel_bg", "toolbar_bg")),
    ("success", ("card_bg", "panel_bg", "toolbar_bg")),
    ("status_idle", ("panel_bg", "toolbar_bg")),
    ("status_connecting", ("panel_bg", "toolbar_bg")),
    ("status_running", ("panel_bg", "toolbar_bg")),
    ("status_error", ("panel_bg", "toolbar_bg")),
    ("brand_bar_fg", ("brand_bar_bg",)),
    ("brand_bar_fg_muted", ("brand_bar_bg",)),
)

GRAPHIC_PAIRS: tuple[tuple[str, tuple[str, ...]], ...] = (
    ("plot_fn", ("plot_bg",)),
    ("plot_fx", ("plot_bg",)),
    ("plot_fy", ("plot_bg",)),
    ("scrollbar_handle", ("scrollbar_bg",)),
    ("scrollbar_handle_hover", ("scrollbar_bg",)),
    ("accent", ("panel_bg", "window_bg", "toolbar_bg")),
    ("accent_hover", ("panel_bg", "toolbar_bg")),
    ("focus_ring", ("window_bg", "input_bg", "panel_bg", "card_bg")),
    ("input_border", ("input_bg", "panel_bg", "card_bg", "toolbar_bg")),
)

VIZ_KEYS = ("plot_fn", "plot_fx", "plot_fy")

# Deliberate, documented exemptions (see apps/studio/docs/ui-palette.md):
# decorative 1px container outlines, and disabled states which WCAG 1.4.3
# explicitly exempts.
DECORATIVE_PAIRS: tuple[tuple[str, tuple[str, ...]], ...] = (
    ("card_border", ("card_bg",)),
    ("panel_border", ("panel_bg", "window_bg")),
    ("plot_grid", ("plot_bg",)),
    ("separator", ("toolbar_bg", "panel_bg")),
)


def _srgb_channel(value: int) -> float:
    channel = value / 255.0
    if channel <= 0.03928:
        return channel / 12.92
    return ((channel + 0.055) / 1.055) ** 2.4


def _rgb(hex_color: str) -> tuple[int, int, int]:
    text = str(hex_color).strip().lstrip("#")
    return tuple(int(text[i : i + 2], 16) for i in (0, 2, 4))  # type: ignore[return-value]


def relative_luminance(hex_color: str) -> float:
    red, green, blue = _rgb(hex_color)
    return (
        0.2126 * _srgb_channel(red)
        + 0.7152 * _srgb_channel(green)
        + 0.0722 * _srgb_channel(blue)
    )


def contrast_ratio(first: str, second: str) -> float:
    high = relative_luminance(first)
    low = relative_luminance(second)
    if high < low:
        high, low = low, high
    return (high + 0.05) / (low + 0.05)


def hue_degrees(hex_color: str) -> float:
    red, green, blue = (value / 255.0 for value in _rgb(hex_color))
    high, low = max(red, green, blue), min(red, green, blue)
    delta = high - low
    if delta == 0:
        return 0.0
    if high == red:
        return (60 * ((green - blue) / delta) + 360) % 360
    if high == green:
        return 60 * ((blue - red) / delta) + 120
    return 60 * ((red - green) / delta) + 240


def _hue_gap(first: str, second: str) -> float:
    delta = abs(hue_degrees(first) - hue_degrees(second))
    return min(delta, 360 - delta)


def audit_palette(verbose: bool = False) -> list[str]:
    """Return the list of palette-rule violations (empty when compliant)."""
    from orisys_app_shared.theme import load_colors

    failures: list[str] = []
    themes = ("dark", "light")
    palettes = {theme: load_colors(theme) for theme in themes}

    dark_keys, light_keys = set(palettes["dark"]), set(palettes["light"])
    if dark_keys != light_keys:
        failures.append(f"token keys differ between themes: {sorted(dark_keys ^ light_keys)}")

    for theme, palette in palettes.items():
        if verbose:
            print(f"  -- {theme} --")
        for key, value in sorted(palette.items()):
            if key == "flow_ramp":
                stops = [stop.strip() for stop in value.split(",") if stop.strip()]
                if not stops:
                    failures.append(f"{theme}.flow_ramp is empty")
                for stop in stops:
                    if not (stop.startswith("#") and len(stop) == 7):
                        failures.append(f"{theme}.flow_ramp stop {stop!r} is not #RRGGBB")
            elif not (str(value).startswith("#") and len(str(value)) == 7):
                failures.append(f"{theme}.{key} = {value!r} is not #RRGGBB")

        for key, backgrounds in TEXT_PAIRS:
            for background in backgrounds:
                ratio = contrast_ratio(palette[key], palette[background])
                if verbose:
                    print(f"     text  {key:19s} on {background:17s} {ratio:5.2f}")
                if ratio < TEXT_MIN_RATIO:
                    failures.append(
                        f"{theme}: text {key} on {background} = {ratio:.2f} "
                        f"(need {TEXT_MIN_RATIO})"
                    )

        for key, backgrounds in GRAPHIC_PAIRS:
            for background in backgrounds:
                ratio = contrast_ratio(palette[key], palette[background])
                if verbose:
                    print(f"     graph {key:19s} on {background:17s} {ratio:5.2f}")
                if ratio < GRAPHIC_MIN_RATIO:
                    failures.append(
                        f"{theme}: graphic {key} on {background} = {ratio:.2f} "
                        f"(need {GRAPHIC_MIN_RATIO})"
                    )

        for index, first in enumerate(VIZ_KEYS):
            for second in VIZ_KEYS[index + 1 :]:
                gap = _hue_gap(palette[first], palette[second])
                high = max(relative_luminance(palette[first]), relative_luminance(palette[second]))
                low = min(relative_luminance(palette[first]), relative_luminance(palette[second]))
                ratio = (high + 0.05) / (low + 0.05)
                if verbose:
                    print(
                        f"     viz   {first:19s} vs {second:17s} "
                        f"dHue={gap:5.1f} LrelRatio={ratio:4.2f}"
                    )
                if gap < VIZ_MIN_HUE_GAP and ratio < VIZ_MIN_LUMINANCE_RATIO:
                    failures.append(
                        f"{theme}: {first}/{second} are too similar "
                        f"(hue gap {gap:.0f} deg, luminance ratio {ratio:.2f})"
                    )

        stops = [stop.strip() for stop in palette["flow_ramp"].split(",") if stop.strip()]
        if len(stops) >= 2:
            luminances = [relative_luminance(stop) for stop in stops]
            if verbose:
                print(f"     ramp  luminances {[round(value, 4) for value in luminances]}")
            if not all(
                luminances[i] < luminances[i + 1] for i in range(len(luminances) - 1)
            ):
                failures.append(f"{theme}: flow_ramp is not monotone in luminance")
            for stop in stops[RAMP_BLEND_STOPS:]:
                ratio = contrast_ratio(stop, palette["arrow_canvas"])
                if ratio < GRAPHIC_MIN_RATIO:
                    failures.append(
                        f"{theme}: flow_ramp stop {stop} on arrow_canvas = "
                        f"{ratio:.2f} (need {GRAPHIC_MIN_RATIO})"
                    )

    for theme, palette in palettes.items():
        if palette["brand_bar_bg"] == palette["window_bg"]:
            failures.append(f"{theme}: brand_bar_bg collides with window_bg")
        if verbose:
            print(f"  -- {theme} documented exemptions --")
            for key, backgrounds in DECORATIVE_PAIRS:
                for background in backgrounds:
                    print(
                        f"     exempt {key:19s} on {background:17s} "
                        f"{contrast_ratio(palette[key], palette[background]):5.2f}"
                    )

    return failures


def main() -> int:
    from PyQt5.QtWidgets import QApplication

    from orisys_app_shared.force.calibration_io import CalSample
    from orisys_app_shared.i18n import set_locale, t
    from orisys_app_shared.theme import build_qss, load_colors
    from orisys_studio.app_window import VIEW_SPLITTER_SIZES, StudioMainWindow

    app = QApplication.instance() or QApplication(sys.argv)
    set_locale("zh_CN")

    section("theme tokens")
    dark = set(load_colors("dark"))
    light = set(load_colors("light"))
    check(dark == light, f"token keys differ: {sorted(dark ^ light)}")
    for theme in ("dark", "light"):
        qss = build_qss(theme)
        check(len(qss) > 1000, f"{theme} qss suspiciously short")
        check(
            load_colors(theme)["arrow_canvas"] != load_colors(theme)["accent"],
            f"{theme}: arrow canvas collides with accent",
        )
        check("QProgressBar::chunk" in qss, f"{theme}: progress bar not styled")
        check("QHeaderView::section" in qss, f"{theme}: table header not styled")
        check("QRadioButton::indicator" in qss, f"{theme}: radio not styled")
        check("QScrollBar::handle" in qss, f"{theme}: scrollbar not styled")
        check("QFrame#brandBar" in qss, f"{theme}: brand bar not styled")
        check("brand_bar_bg" not in qss, f"{theme}: qss leaked a token name")

    section("palette rules")
    palette_failures = audit_palette(verbose=True)
    for failure in palette_failures:
        check(False, failure)
    if not palette_failures:
        check(True, "palette rules hold for both themes")

    section("locale encoding")
    encoding_failures = audit_locale_encoding()
    for failure in encoding_failures:
        check(False, failure)
    if not encoding_failures:
        check(True, "locale files are BOM-free UTF-8 and not mojibake")

    scene_count = 0
    for theme in ("dark", "light"):
        for sensor in ("box", "finger"):
            section(f"window {theme}/{sensor}")
            scene_count += 1
            app.setStyleSheet(build_qss(theme))
            window = StudioMainWindow(
                prefs={
                    "language": "zh_CN",
                    "theme": theme,
                    "sensor_type": sensor,
                    "show_cal_panel": True,
                }
            )
            window.resize(1440, 880)
            window.show()
            app.processEvents()

            check(window.windowTitle() != "", "window title empty")
            check(
                window.status_chip.text() != "",
                "status chip has no phase text",
            )
            check(
                window.toolbar.btn_run.text().strip() not in ("", "▶"),
                f"run button is unlabelled: {window.toolbar.btn_run.text()!r}",
            )

            brand_bar = window.brand_bar
            check(brand_bar.height() >= 28, "brand bar is too short to read")
            check(brand_bar.name.text() != "", "brand bar wordmark empty")
            check(brand_bar.tagline.text() != "", "brand bar tagline empty")
            check(brand_bar.product.text() == t("app.title"), "brand bar product name wrong")
            logo = brand_bar.logo.pixmap()
            if logo is not None and not logo.isNull():
                image = logo.toImage()
                pixels = [
                    image.pixelColor(x, y).alpha()
                    for y in range(image.height())
                    for x in range(image.width())
                ]
                check(any(a < 32 for a in pixels), "brand logo lost its transparency")
                check(any(a >= 200 for a in pixels), "brand logo renders empty")
            else:
                check(not brand_bar.logo.isVisible(), "hidden logo still shown")

            panels = [
                window.mesh3d_panel,
                window.arrow_panel,
                window.force_plots,
                window.cal_panel,
            ]
            for panel, width in zip(panels, window.content_splitter.sizes()):
                if panel.isVisible():
                    check(
                        width >= panel.minimumWidth(),
                        f"{type(panel).__name__} width {width} < min {panel.minimumWidth()}",
                    )

            check(
                window.force_plots.width() >= window.force_plots.minimumWidth(),
                "force plots narrower than its minimum",
            )

            # value cards must keep their text visible
            for card, label in zip(
                window.force_plots.value_cards, window.force_plots.value_labels
            ):
                check(
                    label.height() >= label.fontMetrics().height(),
                    "value card text is clipped",
                )
                check(label.text() != "", "value card is empty")

            # demo data flows through the plots and the calibration table
            for i in range(90):
                window.force_plots.push(i / 30.0, float(i % 7), -1.0, 1.0, unit="N")
            app.processEvents()
            check(
                window.force_plots.history.sample_count > 0,
                "plots did not accept samples",
            )

            window.cal_panel.set_running(True)
            check(window.cal_panel.btn_record.isEnabled(), "record button stays disabled")
            check(
                window.cal_panel.table.columnCount() == 6,
                "the calibration table is no longer the six-column diagnostic view",
            )

            # Drive a real point through the recorder: the table is a view over
            # the recorded points, not over a separate sample list.
            window.cal_recorder.start(
                channel="fn", reference_load_n=1.0, duration_s=1.0
            )
            for index in range(40):
                window.cal_recorder.feed(
                    _calibration_sample(index, fn_raw=100.0 + index * 0.01)
                )
            point = window.cal_recorder.finish_now()
            window.cal_panel.on_record_finished(point)
            app.processEvents()
            check(window.cal_panel.table.rowCount() == 1, "calibration row missing")
            check(
                not window.cal_panel.empty_hint.isVisible(),
                "empty hint still visible with rows",
            )
            check(
                window.cal_panel.fit_label.text() != "",
                "the fit summary is empty",
            )

            # Four points, one of them off-trend (raw 400 where the others imply
            # ~200). The exported model is piecewise-linear, so it passes through
            # every point it is built from: the training residual is zero by
            # construction and the off-trend point can only show up as a
            # *validation* error. The summary must describe that model, not a
            # private least-squares line.
            for load, raw in ((2.0, 400.0), (3.0, 300.6), (5.0, 500.9)):
                window.cal_recorder.start(
                    channel="fn", reference_load_n=load, duration_s=1.0
                )
                for index in range(40):
                    window.cal_recorder.feed(_calibration_sample(index, fn_raw=raw))
                window.cal_panel.on_record_finished(window.cal_recorder.finish_now())
            app.processEvents()
            check(window.cal_panel.table.rowCount() == 4, "calibration rows missing")

            fit = window.cal_recorder.fit("fn")
            check(
                fit.method == "piecewise_linear",
                f"the summary is not about the exported model: {fit.method!r}",
            )
            check(
                fit.breakpoints == 4,
                f"the exported model has {fit.breakpoints} breakpoints, not 4",
            )
            check(
                fit.max_residual_n <= 1e-9,
                "the exported model does not reproduce its own calibration points: "
                f"max residual {fit.max_residual_n}",
            )

            # Hold the off-trend point out: the exported model is then built
            # without it and the misfit becomes visible as a validation error.
            window.cal_panel.table.setCurrentCell(1, 0)
            window.cal_panel._on_toggle_validation()
            app.processEvents()
            check(
                t("cal.fit_validation").split("{")[0].strip()
                in window.cal_panel.fit_label.text(),
                "no validation summary after marking a validation point",
            )
            validation = window.cal_recorder.fit("fn").validation_error_n
            check(
                validation > 0.05,
                f"the off-trend point produced no validation error: {validation}",
            )
            window.cal_panel._on_toggle_validation()

            # Excluding a point removes it from the build, so the exported model
            # no longer passes through it.
            window.cal_panel._on_toggle_excluded()
            app.processEvents()
            check(
                window.cal_panel.table.item(1, 5).text() == t("cal.state_excluded"),
                "the excluded row does not show its state",
            )
            from orisys_app_shared.force.calibration_io import (
                build_export_model,
                build_force_calibration_v2 as _build_v2,
                predict_channel,
            )
            import orisys.calibration as _sdk_calibration

            store = window.cal_panel._store
            model = build_export_model(
                {key: store.channel(key) for key in ("fn", "fx", "fy")}
            )
            predicted = predict_channel(model, "fn", 400.0)
            check(
                abs(predicted - 2.0) > 0.05,
                f"excluding a point left the exported model unchanged: {predicted}",
            )
            # One preparation: the store the panel shows is the prepared model's
            # input, and the export serialises that same object.
            prepared = window.cal_panel._prepared
            check(
                prepared is not None and prepared.ok,
                "the panel has no prepared calibration to show or export",
            )
            check(
                list(store.channel("fn")) == list(prepared.samples["fn"]),
                "the panel store is not the prepared model's input",
            )
            doc, _warnings = _build_v2(prepared)
            export_dir = APP_ROOT / "outputs" / "_cal_export_check"
            if export_dir.exists():
                for stale in export_dir.iterdir():
                    stale.unlink()
            export_dir.mkdir(parents=True, exist_ok=True)
            written = export_dir / "exported_calibration.json"
            import json as _cal_json

            written.write_text(_cal_json.dumps(doc), encoding="utf-8")
            loaded = _sdk_calibration.load(written, strict=True)
            for point in window.cal_recorder.points:
                if point.excluded:
                    continue
                raw = float(point.loaded_stats().mean)
                check(
                    abs(
                        float(loaded.get("fn").convert(raw))
                        - prepared.predict("fn", raw)
                    )
                    <= 1e-9,
                    "the exported file and the panel disagree about the model",
                )
            check(
                len(prepared.samples["fn"]) == 3,
                f"the prepared build has {len(prepared.samples['fn'])} points, not 3",
            )
            window.cal_recorder.reset_session()
            window.cal_panel._refresh_table()

            window._set_phase("running")
            check("status_running" not in window.status_chip.text(), "chip not localized")
            window._set_theme("light" if theme == "dark" else "dark")
            app.processEvents()

            window._persist_prefs()
            check(
                len(window.prefs.get("splitter_sizes", [])) == 4,
                "splitter sizes not persisted",
            )
            window.close()
            app.processEvents()

    section("small window")
    app.setStyleSheet(build_qss("dark"))
    window = StudioMainWindow(
        prefs={
            "language": "en_US",
            "theme": "dark",
            "sensor_type": "finger",
            "show_cal_panel": True,
            "show_finger_3d": True,
        }
    )
    window.resize(1280, 720)
    window.show()
    app.processEvents()
    for panel, width in zip(
        [
            window.mesh3d_panel,
            window.arrow_panel,
            window.force_plots,
            window.cal_panel,
        ],
        window.content_splitter.sizes(),
    ):
        if panel.isVisible():
            check(width >= panel.minimumWidth(), f"1280px: {type(panel).__name__} squeezed")
    oversize = []
    for child in window.findChildren(object):
        if not hasattr(child, "isVisible") or not child.isVisible():
            continue
        if not hasattr(child, "geometry"):
            continue
        parent = child.parentWidget()
        if parent is None or not parent.isVisible():
            continue
        if _inside_scroll_area(child):
            # A scroll area's content is *meant* to exceed its viewport (the
            # toolbar scrolls horizontally on narrow windows).
            continue
        geometry = child.geometry()
        if geometry.width() > parent.width() + 1 or geometry.height() > parent.height() + 1:
            oversize.append(
                f"{type(child).__name__}({getattr(child, 'objectName', lambda: '')()})"
                f" {geometry.width()}x{geometry.height()}"
                f" in {type(parent).__name__} {parent.width()}x{parent.height()}"
            )
    check(not oversize, f"widgets overflow their parent: {oversize}")
    window.close()
    app.processEvents()

    section("top area")
    import orisys_studio.ui.record_status as _record_states
    from orisys_app_shared.record.experiment import RecordStats as _RecordStats

    #: Brand rail + status rail, collapsed settings, must fit in one instrument
    #: line: the previous layout spent this height on a 40 px brand bar and a
    #: tall sensor card stacked above the charts.
    top_area_limit = 78.0
    for theme in ("dark", "light"):
        app.setStyleSheet(build_qss(theme))
        window = StudioMainWindow(
            prefs={"language": "zh_CN", "theme": theme, "sensor_type": "box"}
        )
        window.resize(1440, 880)
        window.show()
        for _ in range(3):
            app.processEvents()
        rail_height = window.brand_bar.height() + window.toolbar.height()
        check(
            rail_height <= top_area_limit,
            f"{theme}: the collapsed top area is {rail_height}px (limit {top_area_limit})",
        )
        check(
            not window.toolbar.settings_expanded(),
            f"{theme}: the settings area starts expanded",
        )
        check(window.toolbar.status_chip.text().strip(), f"{theme}: the phase chip is empty")
        # The sensor is one summary button on the rail; the pickers (and the
        # calibration they belong to) live in the dialog it opens.
        check(
            window.toolbar.btn_sensor.text() == t(
                "sensor.summary", type="BOX", config="sensor.json"
            ),
            f"{theme}: the sensor summary is wrong: "
            f"{window.toolbar.btn_sensor.text()!r}",
        )
        check(
            window.toolbar.btn_sensor.isVisible(),
            f"{theme}: the sensor button is not on the status rail",
        )
        check(
            window.toolbar.camera_group.isVisible(),
            f"{theme}: the live view does not offer the camera picker",
        )
        check(
            not window.toolbar.video_group.isVisible(),
            f"{theme}: the live camera view also shows the video-file group",
        )
        check(
            window.toolbar.calibration_label.text().strip(),
            f"{theme}: the rail has no calibration state",
        )
        check(
            window.toolbar.record_chip.text() == t("record.state_idle"),
            f"{theme}: the idle record state is "
            f"{window.toolbar.record_chip.text()!r}",
        )
        check(
            t("status.phase_running") != t("record.state_idle"),
            "acquiring and recording do not have distinct labels",
        )
        check(
            window.toolbar.record_chip.toolTip() != "",
            "the record chip does not explain its state",
        )
        check(
            not rail_squeezed(window),
            f"{theme}: the status rail squeezes {rail_squeezed(window)}",
        )
        check(
            not hasattr(window.toolbar, "source_combo"),
            f"{theme}: the source mode is still a combobox",
        )
        # The status bar is a notice line, not a second state line: the config
        # file and the phase are already on the rail, and a message must expire.
        check(
            not hasattr(window, "device_label"),
            f"{theme}: the status bar still carries a permanent device line",
        )
        window.statusBar().showMessage("notice")
        check(
            window.statusBar().currentMessage() == "notice",
            f"{theme}: the status bar does not show a message at all",
        )

        # The sensor dialog owns the pickers and the calibration facts.
        window._open_sensor_dialog()
        for _ in range(3):
            app.processEvents()
        dialog = window.sensor_dialog
        check(dialog is not None and dialog.isVisible(), f"{theme}: the sensor dialog did not open")
        check(
            window.sensor_picker.isVisible(),
            f"{theme}: the sensor pickers are not reachable in the dialog",
        )
        check(
            window.sensor_picker.type_label.text() == "传感器"
            and window.sensor_picker.config_label.text() == "传感器配置",
            f"{theme}: the sensor picker labels are not the documented ones: "
            f"{window.sensor_picker.type_label.text()!r} / "
            f"{window.sensor_picker.config_label.text()!r}",
        )
        check(
            dialog.version_label.text() != "" and dialog.axes_label.text() != "",
            f"{theme}: the dialog states no calibration",
        )
        check(
            t("sensor.export_none") in dialog.export_label.text()
            or dialog.btn_apply.isEnabled(),
            f"{theme}: the export row states neither a file nor its absence: "
            f"{dialog.export_label.text()!r}",
        )
        # Changing the product in the dialog reaches the window.
        window.sensor_picker.type_combo.setCurrentIndex(
            window.sensor_picker.type_combo.findData("finger")
        )
        for _ in range(3):
            app.processEvents()
        check(
            window.prefs.get("sensor_type") == "finger",
            f"{theme}: the dialog's product change did not reach the window",
        )
        check(
            "FINGER" in window.toolbar.btn_sensor.text(),
            f"{theme}: the rail summary did not follow the product change: "
            f"{window.toolbar.btn_sensor.text()!r}",
        )
        window.sensor_picker.type_combo.setCurrentIndex(
            window.sensor_picker.type_combo.findData("box")
        )
        for _ in range(3):
            app.processEvents()
        dialog.close()
        app.processEvents()

        # The settings area is one click away, and remembers that it was opened.
        window.toolbar.btn_settings.setChecked(True)
        for _ in range(3):
            app.processEvents()
        expanded_height = window.brand_bar.height() + window.toolbar.height()
        check(
            expanded_height > rail_height,
            f"{theme}: opening the settings area changed nothing "
            f"({expanded_height} vs {rail_height})",
        )
        check(
            window.toolbar.units_combo.isVisible() and window.toolbar.btn_preview.isVisible(),
            f"{theme}: the unit and preview controls are unreachable",
        )
        check(
            window.prefs.get("settings_expanded") is True,
            f"{theme}: the settings state was not persisted",
        )
        check(
            window.act_settings.isChecked(),
            f"{theme}: the View menu does not follow the settings toggle",
        )
        window.toolbar.btn_settings.setChecked(False)
        for _ in range(3):
            app.processEvents()
        check(
            not window.toolbar.settings_expanded(),
            f"{theme}: the settings area could not be collapsed again",
        )
        window.close()
        app.processEvents()

    # English labels are the widest case ("Start recording", "Sensor config"),
    # and the tightest window is 1280: the rail must still fit both.
    set_locale("en_US")
    app.setStyleSheet(build_qss("dark"))
    english_window = StudioMainWindow(
        prefs={"language": "en_US", "theme": "dark", "sensor_type": "finger"}
    )
    english_window.resize(1280, 720)
    english_window.show()
    for _ in range(3):
        app.processEvents()
    check(
        not rail_squeezed(english_window),
        f"en_US at 1280x720: the status rail squeezes {rail_squeezed(english_window)}",
    )
    check(
        t("sensor.summary", type="FINGER", config="sensor.json")
        in english_window.toolbar.btn_sensor.text(),
        f"the sensor summary is not stated in full: "
        f"{english_window.toolbar.btn_sensor.text()!r}",
    )
    english_window.close()
    app.processEvents()
    set_locale("zh_CN")

    # Exactly one *filled* action at a time: a red Stop dominating an otherwise
    # idle top area was the original complaint.
    app.setStyleSheet(build_qss("dark"))
    window = StudioMainWindow(
        prefs={"language": "zh_CN", "theme": "dark", "sensor_type": "box"}
    )
    window.resize(1440, 880)
    window.show()
    app.processEvents()
    check(
        window.toolbar.btn_run.objectName() == "primaryButton",
        f"idle Run is not the filled primary: {window.toolbar.btn_run.objectName()!r}",
    )
    check(
        not window.toolbar.btn_record.isEnabled(),
        "recording is offered without a session",
    )

    stuck = _StuckWorker()
    window._ensure_workers = lambda: None
    window._box_worker = stuck
    window._finger_worker = stuck
    window.toolbar.btn_run.setChecked(True)
    app.processEvents()
    check(
        window.toolbar.btn_run.objectName() == "dangerButton",
        "Cancel is not the filled action while a connect hangs",
    )
    stuck.emit(_fake_packet(1))
    window._on_run_tick()
    app.processEvents()
    check(window._session_phase == "running", "the session never reached running")
    check(
        window.toolbar.btn_run.objectName() == "dangerOutline",
        f"Stop competes with the record action: "
        f"{window.toolbar.btn_run.objectName()!r}",
    )
    check(
        window.toolbar.btn_record.objectName() == "primaryButton",
        "the record action is not the filled primary while acquiring",
    )
    check(
        window._calibration_summary() == t("status.calibrated_all"),
        f"a fully calibrated packet is not reported as such: "
        f"{window._calibration_summary()!r}",
    )
    window.toolbar.set_record_checked(True)
    app.processEvents()
    check(
        window.toolbar.btn_record.objectName() == "dangerButton",
        "stopping the recording is not the filled danger",
    )
    check(
        window.toolbar.btn_run.objectName() == "dangerOutline",
        "two filled actions share the rail while recording",
    )

    real_stats = window._record_stats
    window._record_stats = lambda: (
        _record_states.RECORDING,
        _RecordStats(duration_s=12.4, frames=372, segments=1, dropped_data=3),
        "20240101T000000Z_session0001_deadbeef",
    )
    window._refresh_record_state()
    app.processEvents()
    chip = window.toolbar.record_chip
    check(
        "12.4" in chip.text(),
        f"the record strip does not show the duration: {chip.text()!r}",
    )
    check(
        t("record.dropped", count=3) in chip.text(),
        f"dropped frames are not surfaced: {chip.text()!r}",
    )
    check(
        "3" in chip.toolTip() and "372" in chip.toolTip(),
        f"the record tooltip has no detail: {chip.toolTip()!r}",
    )
    window._record_stats = lambda: (
        _record_states.ERROR,
        _RecordStats(
            frames=10, segments=1, failed=True, write_errors=2, last_error="disk full"
        ),
        "",
    )
    window._refresh_record_state()
    check(
        chip.text() == t("record.state_error", count=2),
        f"a write failure is not reported: {chip.text()!r}",
    )
    check(
        "disk full" in chip.toolTip(),
        f"the record tooltip hides the failure reason: {chip.toolTip()!r}",
    )
    window._record_stats = real_stats
    window.toolbar.set_record_checked(False)
    window._stop_run(reason="user_stop")
    stuck.release()
    window.close()
    app.processEvents()

    section("stopping a hung connect")
    stuck = _StuckWorker()
    window = StudioMainWindow(
        prefs={
            "language": "zh_CN",
            "theme": "dark",
            "sensor_type": "box",
            "source_mode": "camera",
        }
    )
    window.resize(1440, 880)
    window.show()
    window._ensure_workers = lambda: None
    window._box_worker = stuck
    window._finger_worker = stuck
    app.processEvents()

    check(not window.act_stop.isEnabled(), "Stop shortcut is live before a session")
    window.toolbar.btn_run.setChecked(True)
    app.processEvents()

    check(window._session_phase == "connecting", "run did not enter the connecting phase")
    check(
        window.toolbar.btn_run.isEnabled(),
        "Stop is disabled while connecting — a hung connect could not be cancelled",
    )
    check(window.toolbar.btn_run.isChecked(), "run button did not latch into the stop state")
    check(
        window.toolbar.btn_run.text() == t("toolbar.cancel_label"),
        f"connecting label is not the cancel label: {window.toolbar.btn_run.text()!r}",
    )
    check(
        window.toolbar.btn_run.toolTip() == t("toolbar.cancel_tip"),
        "connecting tooltip does not explain how to cancel",
    )
    check(window.act_stop.isEnabled(), "Stop shortcut is disabled while connecting")

    started = time.perf_counter()
    window.toolbar.btn_run.setChecked(False)
    elapsed = time.perf_counter() - started
    check(elapsed < 0.5, f"Stop blocked the GUI for {elapsed:.2f}s on a hung connect")
    check(not window._running, "session stayed active after Stop")
    check(window._session_phase == "idle", "phase did not return to idle after Stop")
    check(
        stuck.thread_still_owned,
        "Stop abandoned the still-running worker thread",
    )

    # The slow-connect hint must point at the escape hatch.
    window.toolbar.btn_run.setChecked(True)
    app.processEvents()
    window._connect_started_at = time.perf_counter() - 3600.0
    window._on_run_tick()
    check(
        window.statusBar().currentMessage() == t("status.connect_slow"),
        f"no slow-connect hint: {window.statusBar().currentMessage()!r}",
    )

    escaped = time.perf_counter()
    window._on_stop_shortcut()
    check(
        time.perf_counter() - escaped < 0.5,
        "Esc did not cancel the hung connect immediately",
    )
    check(not window._running, "Esc left the session running")
    window.close()
    app.processEvents()

    # Let the deliberately-stuck thread finish before the interpreter tears
    # down Qt, otherwise it would outlive the widgets it can reach.
    stuck.release()

    section("record channel")
    import numpy as np

    stuck = _StuckWorker()
    window = StudioMainWindow(
        prefs={
            "language": "zh_CN",
            "theme": "dark",
            "sensor_type": "box",
            "source_mode": "camera",
        }
    )
    window.resize(1440, 880)
    window.show()
    window._ensure_workers = lambda: None
    window._box_worker = stuck
    window._finger_worker = stuck
    window.toolbar.btn_run.setChecked(True)
    app.processEvents()

    check(
        window._on_packet_recorded in stuck.sinks(),
        "the record channel is not attached to the running worker",
    )

    # The record channel must not depend on the UI refresh timer at all.
    for index in range(90):
        stuck.emit(_fake_packet(index))
    check(
        window.session_store.count == 90,
        f"record channel dropped samples without a UI tick: {window.session_store.count}",
    )

    # Invalid readouts must never be averaged in as zeros.
    for index in range(10):
        stuck.emit(_fake_packet(200 + index, valid=False, reason="read failed"))
    slice_ = window.session_store.data()
    check(int(slice_.valid.sum()) == 90, "invalid samples were not marked invalid")
    check(
        not bool(slice_.valid[-1]) and slice_.raw[-1][0] != slice_.raw[-1][0],
        "a failed readout was stored as a number instead of NaN",
    )

    # Calibration sampling must survive the panel being hidden.
    window._show_cal = False
    window._apply_panel_visibility()
    check(not window.cal_panel.isVisible(), "the calibration panel is still visible")
    window.cal_recorder.start(channel="fn", reference_load_n=2.0, duration_s=1.0)
    for index in range(40):
        stuck.emit(_fake_packet(300 + index))
    point = window.cal_recorder.finish_now()
    check(point is not None and point.n_valid == 40, "hidden panel stopped the sampling")
    check(
        point is not None and point.status == "ok",
        f"calibration point was not usable: {getattr(point, 'status', None)}",
    )

    # While recording, the record button must stay enabled — it is the cancel.
    window.cal_panel.set_running(True)
    window.cal_panel._on_record_clicked()
    app.processEvents()
    check(window.cal_panel._recording, "recording did not start")
    check(
        window.cal_panel.btn_record.isEnabled(),
        "the record button is disabled while recording, so it cannot cancel",
    )
    check(
        window.cal_panel.btn_record.text() == t("cal.recording_stop"),
        f"record button does not show the stop label: {window.cal_panel.btn_record.text()!r}",
    )
    window.cal_panel._on_record_clicked()
    app.processEvents()
    check(not window.cal_panel._recording, "the recording could not be cancelled")

    # The depth view must not fall back to the processed frame.
    window.arrow_panel.set_view_mode("depth")
    window._last_rendered_view_mode = None
    stuck.emit(_fake_packet(400, depth=None))
    window._on_run_tick()
    app.processEvents()
    check(
        window.arrow_panel.image_label.text() == t("panels.depth_unavailable"),
        f"missing depth was not reported: {window.arrow_panel.image_label.text()!r}",
    )
    window._last_rendered_view_mode = None
    stuck.emit(_fake_packet(401, depth=np.linspace(0.0, 1.0, 64).reshape(8, 8)))
    window._on_run_tick()
    first_scale = window.arrow_panel.depth_scale_label.text()
    window._last_rendered_view_mode = None
    stuck.emit(_fake_packet(402, depth=np.linspace(0.0, 9.0, 64).reshape(8, 8)))
    window._on_run_tick()
    check(
        window.arrow_panel.depth_scale_label.text() == first_scale and first_scale != "",
        "the depth colour scale re-fitted per frame instead of staying fixed",
    )

    window.close()
    app.processEvents()
    stuck.release()

    section("instrument panels")
    window = StudioMainWindow(
        prefs={"language": "zh_CN", "theme": "dark", "sensor_type": "box"}
    )
    window.resize(1440, 880)
    window.show()
    app.processEvents()

    plots_panel = window.force_plots
    check(
        plots_panel.value_group.y() < plots_panel.plot_frame.y(),
        "the axis readouts are not above the charts",
    )
    check(
        all(label.text() for label in plots_panel.value_labels),
        "an axis readout is empty before any sample",
    )
    for label in plots_panel.value_labels:
        check(
            label.height() >= label.fontMetrics().height(),
            "an axis readout is clipped",
        )
        check(
            label.fontMetrics().height() >= 20,
            f"the axis readouts are not large digits: "
            f"{label.font().family()} {label.fontMetrics().height()}px",
        )
    check(
        [plot.getAxis("bottom").style.get("showValues") for plot in plots_panel.plots]
        == [False, False, True],
        "the three charts do not share one bottom time axis",
    )

    arrow = window.arrow_panel
    check(
        arrow.scale_label.isVisible() and arrow.scale_label.text(),
        "the arrow view does not show its display magnification",
    )
    check(
        "2" in arrow.scale_label.text(),
        f"the box magnification is not the documented 2x: {arrow.scale_label.text()!r}",
    )
    check(
        arrow.pipeline_label.isVisible() and arrow.pipeline_label.text(),
        "the arrow view does not name its pipeline",
    )
    check(
        arrow.area_label.isVisible() and arrow.area_label.text(),
        "the arrow view does not report the valid area",
    )
    check(
        not arrow.colorbar.isVisible(),
        "the depth colour bar is shown in the arrow view",
    )
    arrow.set_view_mode("depth")
    arrow.set_depth_scale("深度色标 0.000 – 1.000")
    for _ in range(2):
        app.processEvents()
    check(arrow.colorbar.isVisible(), "the depth colour bar is hidden in the depth view")
    check(
        not arrow.scale_label.isVisible(),
        "the arrow magnification is still shown in the depth view",
    )
    check(
        arrow.depth_scale_label.isVisible() and arrow.depth_scale_label.text(),
        "the depth range is not shown next to its colour bar",
    )
    arrow.set_view_mode("arrows_pure")
    for _ in range(2):
        app.processEvents()
    check(
        not arrow.colorbar.isVisible() and arrow.scale_label.isVisible(),
        "leaving the depth view did not restore the arrow legend",
    )

    # The overview strip is the timeline control: dragging it pans the window.
    stuck = _StuckWorker()
    window._ensure_workers = lambda: None
    window._box_worker = stuck
    window._finger_worker = stuck
    window.toolbar.btn_run.setChecked(True)
    app.processEvents()
    for index in range(120):
        stuck.emit(_fake_packet(index + 100))
    window._on_run_tick()
    for _ in range(3):
        app.processEvents()
    check(
        window.session_store.count == 120,
        f"the session store missed samples: {window.session_store.count}",
    )
    first, last = window.session_store.extent()
    check(last > first, "the session store has no extent to browse")
    check(
        plots_panel.window_label.text() != "",
        "the overview strip has no window readout",
    )
    plots_panel.show_all()
    app.processEvents()
    check(plots_panel.mode() == "browse", "the overview button did not enter browsing")
    target = (first + (last - first) * 0.25, first + (last - first) * 0.5)
    plots_panel.overview_region.setRegion(target)
    for _ in range(3):
        app.processEvents()
    dragged = plots_panel.window()
    check(
        abs(dragged[0] - target[0]) < 0.05 and abs(dragged[1] - target[1]) < 0.05,
        f"dragging the overview did not move the window: {dragged} vs {target}",
    )
    check(
        plots_panel.mode() == "browse",
        "dragging the overview left the charts in live mode",
    )
    window.brand_bar.btn_live.click()
    for _ in range(2):
        app.processEvents()
    check(
        plots_panel.mode() == "follow",
        "the brand rail's live item did not return to live mode",
    )
    check(
        window.brand_bar.btn_live.property("navActive") == "true",
        "the live nav item is not marked as the current view",
    )
    window.act_cal_panel.setChecked(False)
    app.processEvents()
    window.brand_bar.btn_calibration.click()
    app.processEvents()
    check(
        window.cal_panel.isVisible(),
        "the calibration nav item did not reveal the panel",
    )
    window.brand_bar.btn_calibration.click()
    for _ in range(3):
        app.processEvents()
    from PyQt5.QtWidgets import QHeaderView as _QHeaderView

    sizes = window.content_splitter.sizes()
    check(
        window._view_preset == "calibration",
        f"the calibration nav item did not switch the view: {window._view_preset!r}",
    )
    check(
        window.cal_panel.isVisible() and not window.arrow_panel.isVisible(),
        "the calibration view does not trade the 2D panel for the calibration panel",
    )
    check(
        sizes[3] >= 500,
        f"the calibration panel is too narrow for its table: {sizes[3]}px",
    )
    check(
        window.cal_panel.table.horizontalHeader().sectionResizeMode(0)
        == _QHeaderView.ResizeToContents,
        "the calibration columns can still be elided instead of scrolled",
    )
    check(
        window.cal_panel.scroll.isVisible(),
        "the calibration panel cannot scroll to its own controls",
    )
    for button in (
        window.cal_panel.btn_apply,
        window.cal_panel.btn_export,
        window.cal_panel.btn_toggle_validation,
    ):
        check(
            button.height() >= button.fontMetrics().height(),
            f"a calibration button is cut off: {button.text()!r}",
        )
        check(
            button.width() >= button.sizeHint().width(),
            f"a calibration button is clipped: {button.text()!r} "
            f"({button.width()} < {button.sizeHint().width()})",
        )

    window.brand_bar.btn_playback.click()
    for _ in range(3):
        app.processEvents()
    check(
        window._view_preset == "replay",
        f"the replay nav item did not switch the view: {window._view_preset!r}",
    )
    check(
        not window.cal_panel.isVisible() and window.arrow_panel.isVisible(),
        "the replay view is not the 2D + charts arrangement",
    )
    # No recording is open yet: the charts keep following the live session
    # instead of pretending to replay something, and the layout is the live one.
    check(not window.replay.is_loaded(), "a recording is open before one was chosen")
    check(
        window.force_plots.mode() == "follow",
        "the replay view browses before a recording is open",
    )
    # The replay view is the live arrangement, measured rather than assumed: the
    # splitter hands out its handles' width, so compare like with like.
    window.brand_bar.btn_live.click()
    for _ in range(3):
        app.processEvents()
    live_sizes = tuple(window.content_splitter.sizes())
    window.brand_bar.btn_playback.click()
    for _ in range(3):
        app.processEvents()
    replay_sizes = tuple(window.content_splitter.sizes())
    check(
        replay_sizes == live_sizes,
        f"the replay view is not the live arrangement: {replay_sizes} vs {live_sizes}",
    )
    check(
        not hasattr(window, "replay_bar"),
        "the replay view still carries a separate bar",
    )
    check(
        window.toolbar.btn_replay_video.isVisible(),
        "the replay view does not offer a video to replay",
    )
    # The one difference between the two views: the source slot.
    window.brand_bar.btn_live.click()
    for _ in range(3):
        app.processEvents()
    check(
        not window.toolbar.btn_replay_video.isVisible()
        and window.toolbar.source_slot.isVisible(),
        "the live view still shows the replay's video picker",
    )
    window.brand_bar.btn_live.click()
    for _ in range(3):
        app.processEvents()
    sizes = window.content_splitter.sizes()
    check(
        window._view_preset == "live",
        f"the live nav item did not switch the view: {window._view_preset!r}",
    )
    check(
        sizes[2] > sizes[1],
        f"the charts are not given more room than the 2D panel: {sizes}",
    )
    check(
        window.force_plots.mode() == "follow",
        "the live view did not resume following the latest samples",
    )
    check(
        window.brand_bar.btn_live.property("navActive") == "true",
        "the live nav item is not marked as the current view",
    )
    window._stop_run(reason="user_stop")
    stuck.release()
    for _ in range(3):
        app.processEvents()

    # The 2D area keeps the shape of the image it shows, instead of stretching a
    # 16:9 frame into whatever the panel happens to be.
    finger_window = StudioMainWindow(
        prefs={
            "language": "zh_CN",
            "theme": "dark",
            "sensor_type": "finger",
            "show_finger_3d": False,
        }
    )
    finger_window.resize(1440, 880)
    finger_window.show()
    for _ in range(3):
        app.processEvents()
    image = finger_window.arrow_panel.image_label
    check(
        abs(image.aspect() - 16.0 / 9.0) < 0.01,
        f"the 2D area is not 16:9 for a finger sensor: {image.aspect()}",
    )
    check(
        abs(image.height() - image.width() / image.aspect()) <= 2,
        "the 2D image area does not follow the output image's aspect ratio: "
        f"{image.width()}x{image.height()}",
    )
    finger_window.close()
    app.processEvents()
    check(
        window.toolbar.record_chip.text() == t("record.state_idle"),
        f"the record strip did not fall back to idle: "
        f"{window.toolbar.record_chip.text()!r}",
    )
    window.close()
    app.processEvents()

    section("chart header and unit chip")
    from orisys_studio.ui.force_plots import unit_display

    header_window = StudioMainWindow(
        prefs={"language": "zh_CN", "theme": "dark", "sensor_type": "box"}
    )
    header_window.resize(1440, 880)
    header_window.show()
    for _ in range(3):
        app.processEvents()
    header_plots = header_window.force_plots
    for button, name in (
        (header_plots.btn_overview, "zoom to fit"),
        (header_plots.btn_box_zoom, "box zoom"),
        (header_plots.btn_latest, "back to latest"),
    ):
        check(button.text() == "", f"the {name} action still shows text")
        check(not button.icon().isNull(), f"the {name} action has no icon")
        check(button.toolTip() != "", f"the {name} action has no tooltip")
        check(button.accessibleName() != "", f"the {name} action has no accessible name")
    check(
        isinstance(header_plots.unit_badge, type(header_plots.btn_overview)),
        "the unit chip is not a button",
    )
    check(
        header_plots.unit_badge.toolTip() != "",
        "the unit chip does not say what it does",
    )
    # The chip switches the same unit everywhere: the charts and the toolbar.
    before_unit = header_plots.unit()
    header_plots.unit_badge.click()
    app.processEvents()
    check(
        header_plots.unit() != before_unit,
        f"the unit chip did not switch the charts: {header_plots.unit()}",
    )
    check(
        ("newton" if header_plots.unit() == "N" else "raw")
        == header_window.toolbar.units(),
        "the unit chip and the toolbar disagree about the unit",
    )
    check(
        header_plots.unit_badge.text() == unit_display(header_plots.unit()),
        f"the chip does not state the active unit: {header_plots.unit_badge.text()!r}",
    )
    header_plots.unit_badge.click()
    app.processEvents()
    check(
        header_plots.unit() == before_unit,
        "the unit chip does not switch back",
    )
    # The arrow legend says what the factor multiplies.
    check(
        "×" in header_window.arrow_panel.scale_label.text(),
        "the arrow footer lost its magnification",
    )
    check(
        "位移" in header_window.arrow_panel.scale_label.text()
        or "displacement" in header_window.arrow_panel.scale_label.text(),
        f"the arrow footer does not say what is magnified: "
        f"{header_window.arrow_panel.scale_label.text()!r}",
    )
    # The header's mode label shares its row with three icon buttons and the unit
    # chip: the long form of the mode sentence was cut mid-word in English.
    for lang in ("zh_CN", "en_US"):
        header_window._set_language(lang)
        for _ in range(3):
            app.processEvents()
        for mode, name in ((False, "follow"), (True, "browse")):
            if mode:
                header_plots.set_window(0.2, 1.0)
            app.processEvents()
            label = header_plots.mode_label
            check(
                label.width() >= label.sizeHint().width(),
                f"{lang}/{name}: the chart mode label is clipped: "
                f"{label.width()} < {label.sizeHint().width()} ({label.text()!r})",
            )
            check(
                label.toolTip() != "",
                f"{lang}/{name}: the mode label does not explain itself",
            )
    # The locale is process-wide: leave it where the other sections expect it.
    header_window._set_language("zh_CN")
    app.processEvents()
    header_window.close()
    app.processEvents()

    section("acquisition correctness")
    import csv as _csv
    import shutil as _shutil
    import numpy as np

    # A device that only confirms its calibration a moment after the first
    # frames reports raw counts for those frames. They must never be drawn on the
    # newton axis: that was the tall transient at the start of every session.
    stuck = _StuckWorker()
    window = StudioMainWindow(
        prefs={
            "language": "zh_CN",
            "theme": "dark",
            "sensor_type": "box",
            "source_mode": "camera",
        }
    )
    window.resize(1440, 880)
    window.show()
    window._ensure_workers = lambda: None
    window._box_worker = stuck
    window._finger_worker = stuck
    for _ in range(3):
        app.processEvents()
    window._start_run()
    window._run_timer.stop()
    window._set_phase("running")
    plots = window.force_plots
    for index in range(3):
        packet = _fake_packet(index, calibrated_axes=())
        packet.force_calibrated = False
        stuck.emit(packet)
        window._on_run_tick()
    check(
        plots.unit() == "raw",
        f"an uncalibrated device is not shown in raw units: {plots.unit()}",
    )
    for index in range(3, 40):
        stuck.emit(_fake_packet(index))
        window._on_run_tick()
    state = plots.history.state()
    check(plots.unit() == "N", f"the unit did not follow the calibration: {plots.unit()}")
    check(
        plots.history.sample_count == 37,
        f"the raw frames were kept in the newton buffer: "
        f"{plots.history.sample_count} samples",
    )
    peak = (
        float(np.nanmax(np.abs(state.values[:, 0]))) if state is not None else float("inf")
    )
    check(
        state is not None and peak < 5.0,
        f"a raw count is still drawn on the newton axis (peak {peak})",
    )

    # A new session must not inherit the previous one's samples.
    window._stop_run(reason="user_stop")
    window._start_run()
    window._run_timer.stop()
    window._set_phase("running")
    check(
        plots.history.sample_count == 0 and plots.mode() == "follow",
        f"a new session started with {plots.history.sample_count} old samples",
    )

    # While recording, the reported duration is the span captured so far: the
    # record strip used to sit at 00:00.0 for the whole recording.
    app_module = sys.modules["orisys_studio.app_window"]
    scratch = APP_ROOT / "outputs" / "_correctness_check"
    _shutil.rmtree(scratch, ignore_errors=True)
    scratch.mkdir(parents=True, exist_ok=True)
    original_root = app_module.recordings_dir
    app_module.recordings_dir = lambda: scratch
    try:
        window.toolbar.btn_record.setChecked(True)
        app.processEvents()
        check(window.recorder.is_recording, "the recording did not start")
        for index in range(96):
            # 48 frames per second of acquisition time: above the 30 fps the
            # sensor config declares, which is what the container must follow.
            packet = _fake_packet(index, mono_t=index / 48.0)
            packet.fps = 48.0
            stuck.emit(packet)
            window._on_run_tick()
        live_stats = window.recorder.stats()
        check(
            live_stats.duration_s > 1.5,
            f"the live recording duration stayed at {live_stats.duration_s}",
        )
        check(
            "00:0" not in window.toolbar.record_chip.text()
            or window.toolbar.record_chip.text()
            != t("record.state_recording", duration="00:00.0"),
            f"the record strip does not count up: "
            f"{window.toolbar.record_chip.text()!r}",
        )
        check(
            abs(window._video_fps() - 30.0) < 0.01,
            f"the video rate is not the sensor config's: {window._video_fps()}",
        )
        window.toolbar.btn_record.setChecked(False)
        app.processEvents()
        report = window._record_last_report
        check(report is not None, "no record report was published")
        if report is not None:
            check(
                report.stats.resampled_video > 0,
                "the faster-than-configured frames were not reported",
            )
            with (report.directory / "frames.csv").open(encoding="utf-8") as handle:
                rows = list(_csv.DictReader(handle))
            check(
                len(rows) == 96,
                f"the frame rows were thinned by the video pacing: {len(rows)}",
            )
            check(
                any("faster than" in problem for problem in report.problems),
                f"the report does not explain the resampled frames: {report.problems}",
            )
            import cv2 as _cv2

            segments = sorted(report.directory.glob("raw_*.mp4"))
            check(bool(segments), "the recording wrote no video segment")
            if segments:
                capture = _cv2.VideoCapture(str(segments[0]))
                try:
                    written = int(capture.get(_cv2.CAP_PROP_FRAME_COUNT))
                    container_fps = float(capture.get(_cv2.CAP_PROP_FPS))
                finally:
                    capture.release()
                check(
                    abs(container_fps - 30.0) < 1.0,
                    f"the video declares {container_fps} fps, not the sensor's 30",
                )
                check(
                    55 <= written <= 65,
                    f"the video holds {written} frames for 2 s at 30 fps",
                )
    finally:
        app_module.recordings_dir = original_root
        _shutil.rmtree(scratch, ignore_errors=True)

    # The rail's FPS is the worker's *delivered* frame rate. It used to be a count
    # of loop iterations (a 30 fps device read 63), so the number the rail prints
    # must be the packet's, verbatim.
    window.act_show_fps.setChecked(True)
    app.processEvents()
    packet = _fake_packet(0, mono_t=0.0)
    packet.fps = 30.4
    stuck.emit(packet)
    window._on_run_tick()
    app.processEvents()
    check(
        "30.4 FPS" in window.toolbar.source_summary.text(),
        f"the rail does not show the delivered frame rate: "
        f"{window.toolbar.source_summary.text()!r}",
    )
    window.act_show_fps.setChecked(False)
    app.processEvents()

    window._stop_run(reason="user_stop")
    stuck.release()
    app.processEvents()

    section("replay owns the 2D pane")
    # A replay running next to a live session must not be overwritten by the
    # camera: the pane belongs to whichever source the view is showing.
    replay_root = APP_ROOT / "outputs" / "_pane_check"
    _shutil.rmtree(replay_root, ignore_errors=True)
    replay_root.mkdir(parents=True, exist_ok=True)
    from orisys_app_shared.record import ExperimentRecorder, RecordConfig

    recorder = ExperimentRecorder(RecordConfig(video=True, fps=30.0))
    recording = recorder.start(root=replay_root, session_id=1, metadata={})
    for index in range(20):
        # A raw-only recording: no calibration curve, so the calibrated columns
        # stay empty. Showing that in newton mode would draw three blank charts.
        packet = _fake_packet(index)
        packet.force_calibrated = False
        recorder.on_packet(packet)
    recorder.stop()
    stuck = _StuckWorker()
    pane_window = StudioMainWindow(
        prefs={"language": "zh_CN", "theme": "dark", "sensor_type": "box"}
    )
    pane_window.resize(1440, 880)
    pane_window.show()
    pane_window._ensure_workers = lambda: None
    pane_window._box_worker = stuck
    pane_window._finger_worker = stuck
    pane_window._start_run()
    pane_window._run_timer.stop()
    pane_window._set_phase("running")
    pane_window.toolbar.set_units("newton")
    app.processEvents()
    pane_window.brand_bar.btn_playback.click()
    app.processEvents()
    check(pane_window._load_recording(recording), "the replay could not open the recording")
    app.processEvents()
    check(pane_window._replay_owns_image(), "the replay does not own the 2D pane")
    # The recording has no calibrated axis, so newton would be an empty chart.
    check(
        pane_window.force_plots.unit() == "raw",
        f"a raw-only recording was shown in {pane_window.force_plots.unit()}",
    )
    check(
        pane_window.toolbar.units() == "raw",
        "the toolbar and the charts disagree about a recording's unit",
    )
    check(
        pane_window.force_plots.unit_badge.text() == t("units.raw_short"),
        "the chart's unit chip disagrees with the charts",
    )
    drawn = [int(curve.getData()[0].size) for curve in pane_window.force_plots.curves]
    check(all(count > 0 for count in drawn), f"the recording drew nothing: {drawn}")
    # The cards read the point under the playhead, not the live acquisition.
    duration = pane_window.replay.duration_s()
    pane_window.replay.set_position(duration)
    app.processEvents()
    cursor_card = pane_window.force_plots.value_labels[0].text()
    check(
        cursor_card not in ("", t("chart.value_unavailable")),
        f"the replay readout is empty: {cursor_card!r}",
    )
    check(
        float(cursor_card) > 9.0,
        f"the readout is not the sample at the cursor: {cursor_card}",
    )
    before_key = pane_window.arrow_panel.image_label.pixmap().cacheKey()
    before_text = pane_window.arrow_panel.image_label.text()
    for index in range(3):
        packet = _fake_packet(index, mono_t=index / 30.0)
        packet.raw_frame = np.full((24, 32, 3), 200, np.uint8)
        stuck.emit(packet)
        pane_window._on_run_tick()
    app.processEvents()
    check(
        pane_window.arrow_panel.image_label.pixmap().cacheKey() == before_key
        and pane_window.arrow_panel.image_label.text() == before_text,
        "a live frame overwrote the replay's picture",
    )
    check(
        pane_window.force_plots.unit() == "raw",
        "a live sample switched the unit of the recording being replayed",
    )
    check(
        pane_window.force_plots.value_labels[0].text() == cursor_card,
        "a live sample overwrote the replay's readout",
    )
    pane_window.brand_bar.btn_live.click()
    app.processEvents()
    check(
        not pane_window._replay_owns_image(),
        "the live view still hands the 2D pane to the replay",
    )
    pane_window._on_run_tick()
    app.processEvents()
    pane_window.replay.close()
    pane_window._stop_run(reason="user_stop")
    stuck.release()
    pane_window.close()
    app.processEvents()
    _shutil.rmtree(replay_root, ignore_errors=True)

    section("clean shutdown")
    # A camera SDK leaves native threads behind; the entry point must still come
    # back to the console. This runs the real ``main()`` in a child process and
    # closes the window from a timer, so a hang shows up as a timeout.
    import subprocess as _subprocess

    script = (
        "import os, sys\n"
        "os.environ.setdefault('QT_QPA_PLATFORM', 'offscreen')\n"
        "os.environ.setdefault('QT_QPA_FONTDIR', r'C:\\Windows\\Fonts')\n"
        "from PyQt5.QtCore import QTimer\n"
        "import orisys_studio.main as studio_main\n"
        "show = studio_main.StudioMainWindow.show\n"
        "def show_and_close(self):\n"
        "    show(self)\n"
        "    QTimer.singleShot(400, self.close)\n"
        "studio_main.StudioMainWindow.show = show_and_close\n"
        "raise SystemExit(studio_main.main())\n"
    )
    env = dict(os.environ)
    env["PYTHONPATH"] = os.pathsep.join(
        [str(REPO_ROOT / "shared" / "src"), str(APP_ROOT / "src"), env.get("PYTHONPATH", "")]
    )
    started = time.perf_counter()
    try:
        completed = _subprocess.run(
            [sys.executable, "-c", script],
            cwd=str(APP_ROOT),
            env=env,
            capture_output=True,
            timeout=60,
        )
        elapsed = time.perf_counter() - started
        print(f"  window closed and the process returned in {elapsed:.1f}s")
        check(
            completed.returncode == 0,
            f"the app exited with {completed.returncode}: "
            f"{completed.stderr[-400:]!r}",
        )
        check(
            elapsed < 45.0,
            f"closing the window did not return to the console ({elapsed:.1f}s)",
        )
    except _subprocess.TimeoutExpired:
        check(False, "the app never exited after its window was closed")

    section("experiment record")
    import shutil as _shutil

    scratch = APP_ROOT / "outputs" / "_record_check"
    _shutil.rmtree(scratch, ignore_errors=True)
    scratch.mkdir(parents=True, exist_ok=True)
    import orisys_studio.app_window as _app_module

    _app_module.recordings_dir = lambda: scratch

    stuck = _StuckWorker()
    window = StudioMainWindow(
        prefs={
            "language": "zh_CN",
            "theme": "dark",
            "sensor_type": "box",
            "source_mode": "camera",
        }
    )
    window.resize(1440, 880)
    window.show()
    window._ensure_workers = lambda: None
    window._box_worker = stuck
    window._finger_worker = stuck
    window._start_run()
    window._run_timer.stop()
    window._set_phase("running")
    app.processEvents()

    check(
        window.toolbar.btn_record.isEnabled(),
        "the record control is disabled while a session is running",
    )
    check(
        window.toolbar.btn_record.text() == t("record.start_label"),
        f"record button label is wrong: {window.toolbar.btn_record.text()!r}",
    )
    check(
        window.toolbar.record_mode() == "video_data",
        "the default recording mode is not video+data",
    )

    window.toolbar.btn_record.setChecked(True)
    app.processEvents()
    check(window.recorder.is_recording, "the recording did not start")
    check(
        window.toolbar.btn_record.isEnabled()
        and window.toolbar.btn_record.text() == t("record.stop_label"),
        "the record button is not a usable stop control",
    )
    check(
        not window.toolbar.record_mode_combo.isEnabled(),
        "the recording mode can be changed mid-recording",
    )

    for index in range(30):
        stuck.emit(_fake_packet(index))
        window._on_run_tick()
    stuck.emit(_fake_packet(90, valid=False, reason="read failed"))
    window._on_run_tick()
    # The zeroing is a *request*; the event is recorded only once the acquisition
    # thread confirms it took effect (the stub confirms immediately).
    stuck.on_reset_applied = window._on_reset_applied
    window._on_reset()
    window._on_run_tick()
    app.processEvents()

    window.toolbar.btn_record.setChecked(False)
    app.processEvents()
    report = window._record_last_report
    check(not window.recorder.is_recording, "the recording did not stop")
    check(report is not None and report.ok, f"recording reported problems: {getattr(report, 'problems', None)}")
    check(
        not window.toolbar.btn_record.isChecked(),
        "the record button still looks active after the recording stopped",
    )
    check(
        window._record_report_pending is False,
        "a finished recording is still waiting for a report",
    )

    import csv as _csv
    import json as _json

    directory = report.directory
    names = sorted(path.name for path in directory.iterdir())
    check(
        names == ["events.csv", "forces.csv", "frames.csv", "raw_0001.mp4", "session.json"],
        f"unexpected experiment layout: {names}",
    )
    with (directory / "forces.csv").open(encoding="utf-8") as handle:
        rows = list(_csv.DictReader(handle))
    check(tuple(rows[0].keys()) == FORCES_HEADER, "forces.csv header drifted from the spec")
    check(
        rows[-1]["valid"] == "0" and rows[-1]["FN_raw"] == "",
        "a failed readout was written as a number instead of being left empty",
    )
    with (directory / "frames.csv").open(encoding="utf-8") as handle:
        frames = list(_csv.DictReader(handle))
    check(len(frames) == len(rows), "forces.csv and frames.csv disagree on the frame count")
    check(
        all(f["frame_id"] == r["frame_id"] for f, r in zip(frames, rows)),
        "the frame index does not share frame ids with the data",
    )
    meta = _json.loads((directory / "session.json").read_text(encoding="utf-8"))
    check(meta.get("ended_at"), "session.json was not finalised")
    check(meta["format_version"], "session.json has no format version")
    check(
        [event["kind"] for event in meta["events"]] == ["record_started", "zeroing", "record_stopped"],
        f"events not recorded: {[e['kind'] for e in meta['events']]}",
    )
    check(meta["stats"]["frames"] == 31, f"unexpected frame count: {meta['stats']['frames']}")

    window.close()
    app.processEvents()
    stuck.release()
    _shutil.rmtree(scratch, ignore_errors=True)

    section("record failure states")

    from unittest.mock import patch as _patch

    from orisys_app_shared.record.experiment import _SessionWriter as _Writer

    scratch_fail = APP_ROOT / "outputs" / "_record_fail"
    _shutil.rmtree(scratch_fail, ignore_errors=True)
    scratch_fail.mkdir(parents=True, exist_ok=True)
    stuck_fail = _StuckWorker()
    fail_window = StudioMainWindow(
        prefs={
            "language": "zh_CN",
            "theme": "dark",
            "sensor_type": "box",
            "source_mode": "camera",
        }
    )
    fail_window.resize(1440, 880)
    fail_window.show()
    fail_window._ensure_workers = lambda: None
    fail_window._box_worker = stuck_fail
    fail_window._finger_worker = stuck_fail
    fail_window._start_run()
    fail_window._run_timer.stop()
    fail_window._set_phase("running")

    # A directory that cannot be created is a terminal, retryable failure.
    blocked = scratch_fail / "blocked"
    blocked.write_text("", encoding="utf-8")
    _app_module.recordings_dir = lambda: blocked
    fail_window.toolbar.btn_record.setChecked(True)
    app.processEvents()
    check(
        not fail_window.recorder.is_recording,
        "a recording started even though its directory could not be created",
    )
    check(
        not fail_window.toolbar.btn_record.isChecked(),
        "the record button stayed active after the start failed",
    )
    check(
        fail_window.recorder.state == "failed",
        f"a failed start left the recorder in {fail_window.recorder.state!r}",
    )

    # ...and the operator can simply try again.
    _app_module.recordings_dir = lambda: scratch_fail
    fail_window.toolbar.btn_record.setChecked(True)
    app.processEvents()
    check(
        fail_window.recorder.is_recording,
        "the recorder refused to retry after a failed directory",
    )

    # A writer that keeps failing must fail the recording, and the window must
    # consume that report even though ``is_recording`` is already False.
    with _patch.object(_Writer, "write_sample", side_effect=OSError("disk full")):
        for index in range(8):
            stuck_fail.emit(_fake_packet(index))
            fail_window._on_run_tick()
        deadline = time.monotonic() + 3.0
        while (
            fail_window.recorder.stats().write_errors < 5
            and time.monotonic() < deadline
        ):
            app.processEvents()
            time.sleep(0.01)
        check(
            fail_window.recorder.stats().failed,
            "repeated write failures never failed the recording",
        )
        check(
            not fail_window.recorder.is_recording,
            "a dead writer still claimed to be recording",
        )
        fail_window._stop_recording()
        app.processEvents()
        failed_report = fail_window._record_last_report
        check(
            failed_report is not None and failed_report.stats.failed,
            "the window did not consume the failure report",
        )
        check(
            not fail_window.toolbar.btn_record.isChecked(),
            "the record button stayed active after the recording failed",
        )
        check(
            fail_window._session_phase == "error",
            f"the session phase is {fail_window._session_phase!r} after a failed recording",
        )

    fail_window.close()
    app.processEvents()
    stuck_fail.release()
    _app_module.recordings_dir = lambda: scratch
    _shutil.rmtree(scratch_fail, ignore_errors=True)

    section("calibration record identity")

    import json as _cal_json
    from unittest.mock import patch as _patch_mismatch

    import orisys_studio.ui.cal_panel as _cal_panel_module
    import orisys_studio.calibration_service as _cal_service_module
    from PyQt5.QtWidgets import QMessageBox as _QMessageBox

    from orisys_app_shared.force.calibration_io import (
        build_force_calibration_v2 as _build_v2b,
        write_force_calibration as _write_cal,
    )
    from orisys_app_shared.force.calibration_session import (
        build_session_document as _build_session_doc,
    )

    record_dir = APP_ROOT / "outputs" / "_cal_record_check"
    if record_dir.exists():
        for stale in record_dir.iterdir():
            stale.unlink()
    record_dir.mkdir(parents=True, exist_ok=True)

    identity_window = StudioMainWindow(
        prefs={
            "language": "zh_CN",
            "theme": "dark",
            "sensor_type": "box",
            "source_mode": "camera",
        }
    )
    identity_window.resize(1400, 880)
    identity_window.show()
    identity_window.cal_panel.set_running(True)
    taken_points = []
    for load, raw in ((1.0, 100.0), (3.0, 300.0)):
        identity_window.cal_recorder.start(
            channel="fn", reference_load_n=load, duration_s=1.0
        )
        for index in range(20):
            identity_window.cal_recorder.feed(
                _calibration_sample(index, fn_raw=raw)
            )
        taken_points.append(identity_window.cal_recorder.finish_now())
    device_a = record_dir / "device_a_session.json"
    device_a.write_text(
        _cal_json.dumps(
            _build_session_doc(
                taken_points,
                meta={
                    "sensor_type": "box",
                    "sn": "SN-A",
                    "config_ref": "D:/lab/deviceA/sensor.json",
                },
            )
        ),
        encoding="utf-8",
    )
    identity_window.cal_recorder.clear_points()

    # The live device is B; opening A's record must not restamp it.
    panel = identity_window.cal_panel
    panel.set_meta_context(sensor_type="finger", config_ref="D:/lab/deviceB/sensor.json")
    panel.sn_edit.setText("SN-B")
    panel._on_open_record(str(device_a))
    app.processEvents()
    check(
        panel.sn_edit.text() == "SN-A",
        f"the reopened record's SN was overwritten: {panel.sn_edit.text()!r}",
    )
    meta = panel._export_meta()
    check(meta["sensor_type"] == "box", "the record's sensor type was overwritten")
    check(meta["sn"] == "SN-A", "the record's SN was not kept")
    check(
        meta["config_ref"] == "D:/lab/deviceA/sensor.json",
        f"the record's config was overwritten: {meta['config_ref']!r}",
    )
    check(
        str(meta.get("source_record", "")).endswith(device_a.name),
        "the export does not reference the source record",
    )
    saved = sorted(record_dir.glob("calibration_session_box_*.json"))
    with _patch_mismatch.object(
        _cal_panel_module, "calibration_export_dir", lambda: record_dir
    ):
        with _patch_mismatch.object(
            _cal_service_module, "calibration_export_dir", lambda: record_dir
        ):
            with _patch_mismatch.object(
                _cal_panel_module.QMessageBox, "information", lambda *a, **k: None
            ):
                panel._on_save_record()
    saved = sorted(record_dir.glob("calibration_session_box_*.json"))
    check(bool(saved), "saving a reopened record produced no file")
    if saved:
        saved_meta = _cal_json.loads(saved[-1].read_text(encoding="utf-8"))["meta"]
        check(
            saved_meta.get("sn") == "SN-A" and saved_meta.get("sensor_type") == "box",
            f"the saved record was restamped: {saved_meta.get('sn')!r}",
        )
    doc, _warnings = _build_v2b(panel._prepared)
    check(
        doc["meta"]["sn"] == "SN-A" and doc["meta"]["sensor_type"] == "box",
        "the exported coefficients carry the wrong device identity",
    )

    # A reopened point with only its samples can still be inspected.
    reopened = identity_window.cal_recorder.points[0]
    for entry in _build_session_doc([reopened])["points"]:
        entry["trace"] = {}
    dialog = panel.point_dialog(reopened)
    check(dialog is not None, "a reopened point could not be inspected")
    if dialog is not None:
        check(
            len(dialog.plot_widget.ci.items) == 3,
            "the rebuilt diagnostic is not one trace per axis",
        )
        dialog.close()

    # Applying a calibration that names another device is flagged and defaults
    # to "no".
    stuck_identity = _StuckWorker()
    identity_window._ensure_workers = lambda: None
    identity_window._box_worker = stuck_identity
    identity_window._finger_worker = stuck_identity
    coefficients = record_dir / "device_a_coefficients.json"
    _write_cal(doc, coefficients)
    check(
        bool(
            identity_window.calibration_target_mismatch(
                str(coefficients),
                sensor_type="finger",
                config_ref="D:/lab/B/sensor.json",
            )
        ),
        "a calibration for another device was not reported as a mismatch",
    )
    check(
        not identity_window.calibration_target_mismatch(
            str(coefficients),
            sensor_type="box",
            config_ref="D:/lab/deviceA/sensor.json",
        ),
        "matching identities were reported as a mismatch",
    )
    with _patch_mismatch.object(
        _QMessageBox, "question", staticmethod(lambda *a, **k: _QMessageBox.No)
    ):
        identity_window._on_calibration_apply(str(coefficients))
    check(
        not stuck_identity.calibration_requests,
        "a mismatched calibration was applied after the user declined",
    )
    check(
        identity_window.statusBar().currentMessage() == t("cal.apply_mismatch_skipped"),
        f"the refusal was not reported: {identity_window.statusBar().currentMessage()!r}",
    )
    # A matching calibration still goes through the normal confirmation.
    identity_window.sensor_picker.set_sensor_type("box")
    with _patch_mismatch.object(
        _QMessageBox, "question", staticmethod(lambda *a, **k: _QMessageBox.Yes)
    ):
        identity_window._on_calibration_apply(str(coefficients))
    check(
        stuck_identity.calibration_requests == [str(coefficients)],
        f"a matching calibration was not requested: {stuck_identity.calibration_requests}",
    )

    identity_window.close()
    app.processEvents()
    _shutil.rmtree(record_dir, ignore_errors=True)

    section("display units and time base")
    import math as _math

    stuck_units = _StuckWorker()
    units_window = StudioMainWindow(
        prefs={
            "language": "zh_CN",
            "theme": "dark",
            "sensor_type": "box",
            "source_mode": "camera",
        }
    )
    units_window.resize(1440, 880)
    units_window.show()
    units_window._ensure_workers = lambda: None
    units_window._box_worker = stuck_units
    units_window._finger_worker = stuck_units
    units_window._start_run()
    units_window._run_timer.stop()
    units_window._set_phase("running")
    units_plots = units_window.force_plots
    units_window.toolbar.units_combo.setCurrentIndex(0)  # newton
    units_plots.reset()
    wall = 1_700_000_000.0
    for index in range(90):
        stuck_units.emit(
            _fake_packet(index, timestamp=wall + index / 30.0, mono_t=index / 30.0)
        )
        units_window._on_run_tick()
    before = units_plots.history.state()
    end_before = float(before.times[-1]) if before is not None else -1.0
    check(
        before is not None and end_before < 60.0,
        f"the live X axis is not session-relative (ends at {end_before})",
    )
    for units_index in (1, 0, 1, 0):
        units_window.toolbar.units_combo.setCurrentIndex(units_index)
    app.processEvents()
    after = units_plots.history.state()
    check(
        after is not None and abs(float(after.times[-1]) - end_before) < 1.0,
        "the X axis jumped across a raw/N switch: "
        f"{end_before} -> {None if after is None else after.times[-1]}",
    )
    check(
        units_plots.history.sample_count > 0,
        "the rebuilt history lost every sample",
    )
    units_window.close()
    units_window._box_worker = None
    stuck_units.release()
    app.processEvents()

    # A device with only its normal-force axis calibrated: FN in newtons, and the
    # other two axes explicitly unavailable instead of showing raw counts.
    stuck_one = _StuckWorker()
    one_window = StudioMainWindow(
        prefs={
            "language": "zh_CN",
            "theme": "dark",
            "sensor_type": "box",
            "source_mode": "camera",
        }
    )
    one_window.resize(1440, 880)
    one_window.show()
    one_window._ensure_workers = lambda: None
    one_window._box_worker = stuck_one
    one_window._finger_worker = stuck_one
    one_window._start_run()
    one_window._run_timer.stop()
    one_window._set_phase("running")
    one_window.toolbar.units_combo.setCurrentIndex(0)  # newton
    one_window.force_plots.reset()
    for index in range(10):
        stuck_one.emit(
            _fake_packet(index, calibrated_axes=("fn",), shear_n=float("nan"))
        )
        one_window._on_run_tick()
    app.processEvents()
    one_plots = one_window.force_plots
    check(
        one_plots._available == (True, False, False),
        f"per-axis availability is wrong: {one_plots._available}",
    )
    check(
        one_plots.value_labels[0].text() != t("chart.value_unavailable"),
        "the calibrated axis was reported as unavailable",
    )
    check(
        all(
            one_plots.value_labels[index].text() == t("chart.value_unavailable")
            for index in (1, 2)
        ),
        "an axis without a curve showed a number in newton mode",
    )
    one_state = one_plots.history.state()
    check(
        one_state is not None
        and _math.isfinite(float(one_state.values[:, 0].max())),
        "the calibrated axis was not plotted",
    )
    check(
        one_state is not None
        and not any(_math.isfinite(v) for v in one_state.values[:, 1]),
        "FX carried a value without a calibration curve",
    )
    one_window.close()
    one_window._box_worker = None
    stuck_one.release()
    app.processEvents()

    section("session browsing")
    import numpy as np

    stuck = _StuckWorker()
    window = StudioMainWindow(
        prefs={
            "language": "zh_CN",
            "theme": "dark",
            "sensor_type": "box",
            "source_mode": "camera",
        }
    )
    window.resize(1440, 880)
    window.show()
    window._ensure_workers = lambda: None
    window._box_worker = stuck
    window._finger_worker = stuck
    window._start_run()
    window._run_timer.stop()
    window._set_phase("running")
    for index in range(1500):
        stuck.emit(_fake_packet(index))
    app.processEvents()

    plots = window.force_plots
    check(plots.mode() == "follow", "the charts do not start in live mode")
    check(
        plots.stats_label.text() == "",
        "the selection readout is not blank while following live",
    )
    # Zoom and pan are available while following too: a chart that ignored the
    # mouse could never be dragged into browsing in the first place.
    check(
        all(plot.getViewBox().state["mouseEnabled"][0] for plot in plots.plots),
        "panning and zooming are disabled while following live",
    )
    check(
        not any(cursor.movable for cursor in plots.cursors),
        "the cursor is draggable while following live",
    )

    first, last = window.session_store.extent()
    check(last > first, "the session store has no extent after recording")

    plots.show_all()
    check(plots.mode() == "browse", "the overview did not enter browse mode")
    check(
        all(plot.getViewBox().state["mouseEnabled"][0] for plot in plots.plots),
        "browsing does not enable panning",
    )
    # "Whole session" is the default fit, not a selection: the cards still state
    # the sample under the cursor, and the strip carries no selection summary.
    check(
        plots._selection is None,
        "fitted to the whole session, the cards still hold selection statistics",
    )
    check(
        plots.stats_label.text() == "",
        f"a fitted session shows a selection summary: {plots.stats_label.text()!r}",
    )

    # Decimation must keep the spike while bounding the point count.
    drawn = max(int(curve.getData()[0].size) for curve in plots.curves)
    check(drawn <= 2 * plots._max_draw_points, f"overview drew {drawn} points")
    spike = float(np.nanmax(plots.curves[0].getData()[1]))
    check(spike > 90.0, f"the overview lost the spike: {spike}")

    plots.set_window(10.0, 20.0)
    check(plots.window() == (10.0, 20.0), f"set_window did not apply: {plots.window()}")
    check(
        plots.overview_curve.getData()[0].size > 0,
        "the whole-session overview strip is empty",
    )
    # A window narrower than the session is a selection: its peak becomes the big
    # number on each card and its mean/σ the line under it, while the strip keeps
    # only the size of the selection (the long per-channel line did not fit).
    check(plots._selection is not None, "zooming in did not record a selection")
    summary = plots.stats_label.text()
    check(summary != "", "the strip does not state the size of the selection")
    check(
        "峰" not in summary and "均" not in summary,
        f"the per-channel statistics are still in the strip: {summary!r}",
    )
    check(
        "选区" in summary or "Selection" in summary,
        f"the strip does not say that the numbers describe a selection: {summary!r}",
    )
    expected_peak = float(plots._selection.peaks[0])
    peak_text = (
        f"{expected_peak:.3f}" if plots.unit() == "N" else f"{expected_peak:.1f}"
    )
    check(
        plots.value_labels[0].text() == peak_text,
        f"the FN card is not the selection's peak: {plots.value_labels[0].text()!r}",
    )
    check(
        plots.value_details[0].text() != ""
        and ("均" in plots.value_details[0].text() or "mean" in plots.value_details[0].text()),
        f"the card does not state the selection's mean: "
        f"{plots.value_details[0].text()!r}",
    )
    for card, label, detail in zip(
        plots.value_cards, plots.value_labels, plots.value_details
    ):
        check(
            detail.width() >= detail.sizeHint().width(),
            f"the selection detail line is clipped: "
            f"{detail.width()} < {detail.sizeHint().width()}",
        )
    # Leaving the selection hands the cards back to the cursor readout.
    plots.follow_latest()
    check(plots._selection is None, "the selection survived 'back to latest'")
    check(
        plots.value_details[0].text() == "",
        f"the mean line survived leaving the selection: "
        f"{plots.value_details[0].text()!r}",
    )

    # A user gesture (the signal pyqtgraph emits for a wheel/drag) enters browse;
    # "back to latest" must actually leave it.
    plots._syncing = False
    view_box = plots.plots[0].getViewBox()
    view_box.setXRange(5.0, 8.0, padding=0.0)
    view_box.sigRangeChangedManually.emit([True, False])
    app.processEvents()
    check(plots.mode() == "browse", "a user pan did not enter browse mode")
    check(
        plots.window() == (5.0, 8.0),
        f"the dragged window was not applied: {plots.window()}",
    )
    check(
        all(cursor.movable for cursor in plots.cursors),
        "the cursor is not draggable while browsing",
    )
    plots.follow_latest()
    check(plots.mode() == "follow", "back-to-latest did not restore live mode")
    check(
        not any(cursor.movable for cursor in plots.cursors),
        "the cursor stayed draggable after leaving browsing",
    )
    # A programmatic (or X-link propagated) range change is not a gesture.
    plots._syncing = False
    view_box.setXRange(1.0, 2.0, padding=0.0)
    app.processEvents()
    check(
        plots.mode() == "follow",
        "a programmatic range change switched the view into browsing",
    )

    plots.set_cursor(3.5, emit=True)
    check(
        [round(cursor.value(), 3) for cursor in plots.cursors] == [3.5, 3.5, 3.5],
        "the time cursor is not shared across the three channels",
    )

    # Dragging the shared cursor moves the playhead and notifies the listeners.
    plots.show_all()
    app.processEvents()
    dragged_cursor: list[float] = []
    plots.cursor_moved.connect(dragged_cursor.append)
    plots.cursors[0].setValue(2.5)
    app.processEvents()
    check(
        [round(cursor.value(), 3) for cursor in plots.cursors] == [2.5, 2.5, 2.5],
        "dragging one cursor did not move the shared cursor",
    )
    check(
        dragged_cursor and dragged_cursor[-1] == 2.5,
        f"the cursor drag did not notify the other views: {dragged_cursor}",
    )

    # History browsing is a display pause: capture and recording keep going.
    plots.show_all()
    before = window.session_store.count
    for index in range(1500, 1560):
        stuck.emit(_fake_packet(index))
    check(
        window.session_store.count > before,
        "browsing history stopped the record channel",
    )
    # Unit switches rebuild from the attached source without leaving live mode.
    plots.follow_latest()
    plots._unit = "raw"
    window._on_units_changed("newton")
    app.processEvents()
    check(
        plots.mode() == "follow",
        f"switching units left the charts in browsing: {plots.mode()}",
    )
    check(plots._source_ready, "switching units detached the curve source")
    check(plots._unit == "N", f"the unit switch did not reach the charts: {plots._unit}")

    window.close()
    app.processEvents()
    stuck.release()

    section("views and their source pickers")
    stuck = _StuckWorker()
    window = StudioMainWindow(
        prefs={
            "language": "zh_CN",
            "theme": "dark",
            "sensor_type": "finger",
            "source_mode": "camera",
            "show_finger_3d": True,
        }
    )
    window.resize(1600, 900)
    window.show()
    window._ensure_workers = lambda: None
    window._box_worker = stuck
    window._finger_worker = stuck
    app.processEvents()

    # The 3D panel needs a finger sensor and its own toggle, and no layout preset
    # is involved any more.
    check(window.mesh3d_panel.isVisible(), "the finger 3D panel is hidden in the live view")
    check(window.act_finger_3d.isEnabled(), "the 3D toggle is disabled for a finger sensor")
    check(
        not hasattr(window, "_layout_preset"),
        "the removed layout preset is still part of the window",
    )
    check(
        not hasattr(window, "act_layout_2d"),
        "the removed layout menu entry is still part of the window",
    )

    # Live: the camera picker; replay: the recording picker and no camera.
    check(
        window.toolbar.camera_group.isVisible(),
        "the live view does not show the camera picker",
    )
    window.brand_bar.btn_playback.click()
    for _ in range(3):
        app.processEvents()
    check(
        not window.toolbar.camera_group.isVisible()
        and not window.toolbar.video_group.isVisible(),
        "the replay view still shows the live capture pickers",
    )
    window.brand_bar.btn_live.click()
    for _ in range(3):
        app.processEvents()
    check(
        window.toolbar.camera_group.isVisible(),
        "returning to the live view did not restore the camera picker",
    )

    # A video file is a *replay* source: the live view offers the way back to the
    # camera, and the video is named only in the replay view.
    window.toolbar.set_video_path("C:/tmp/demo.mp4")
    window._set_source_mode("video")
    for _ in range(3):
        app.processEvents()
    check(
        window.toolbar.video_group.isVisible() and not window.toolbar.camera_group.isVisible(),
        "video mode still offers the camera group",
    )
    check(
        "demo.mp4" not in window.toolbar.source_summary.text(),
        f"the live view names a replay's video: "
        f"{window.toolbar.source_summary.text()!r}",
    )
    window.brand_bar.btn_playback.click()
    for _ in range(3):
        app.processEvents()
    check(
        "demo.mp4" in window.toolbar.source_summary.text(),
        f"the rail does not name the video file: {window.toolbar.source_summary.text()!r}",
    )
    window.brand_bar.btn_live.click()
    for _ in range(3):
        app.processEvents()
    check(
        "demo.mp4" not in window.toolbar.source_summary.text(),
        "the video name stayed on the rail after leaving the replay",
    )
    window.toolbar.use_camera_clicked.emit()
    for _ in range(3):
        app.processEvents()
    check(
        window.toolbar.source_mode() == "camera" and window.toolbar.video_path() == "",
        "the way back to the camera did not take effect",
    )

    window.close()
    app.processEvents()
    stuck.release()

    section("replay")
    replay_root = APP_ROOT / "outputs" / "_replay_check"
    _shutil.rmtree(replay_root, ignore_errors=True)
    replay_root.mkdir(parents=True, exist_ok=True)
    from orisys_app_shared.record import ExperimentRecorder, RecordConfig

    recorder = ExperimentRecorder(
        RecordConfig(video=True, fps=30.0, segment_seconds=30.0)
    )
    recording = recorder.start(
        root=replay_root,
        session_id=1,
        metadata={
            "device": {
                "sensor_type": "box",
                "config_ref": str(replay_root / "sensor.json"),
                "config_sha256": "recorded",
            },
            "versions": {"sdk": "0.5.1"},
            "depth": {"stored": False, "replay": "recompute"},
        },
    )
    (replay_root / "sensor.json").write_text('{"camera": {}}\n', encoding="utf-8")
    for index in range(40):
        recorder.on_packet(_fake_packet(index))
    recorder.stop()

    from orisys_studio.replay import ReplayController

    # The replay lives in the main window: one engine, one progress bar, and the
    # charts read the recording itself.
    replay_window = StudioMainWindow(
        prefs={
            "language": "zh_CN",
            "theme": "dark",
            "sensor_type": "box",
            "source_mode": "camera",
        }
    )
    replay_window.resize(1440, 880)
    replay_window.show()
    app.processEvents()
    replay_window.brand_bar.btn_playback.click()
    app.processEvents()
    check(
        replay_window.toolbar.btn_replay_video.isVisible(),
        "the replay view does not offer a recorded video",
    )
    check(
        not replay_window.toolbar.camera_group.isVisible(),
        "the replay view still offers the camera picker",
    )
    check(
        replay_window._load_recording(recording),
        "the replay view could not open the recording",
    )
    app.processEvents()
    replay_window.toolbar.set_video_path(str(replay_root / "raw_0001.mp4"))
    replay_window._refresh_status_rail()
    check(
        "raw_0001.mp4" in replay_window.toolbar.source_summary.text(),
        f"the replay does not name its video: "
        f"{replay_window.toolbar.source_summary.text()!r}",
    )

    replay = replay_window.replay
    replay_plots = replay_window.force_plots
    check(
        replay.position() == 0.0,
        f"replay did not start at the beginning: {replay.position()}",
    )
    check(
        all(int(curve.getData()[0].size) == 40 for curve in replay_plots.curves),
        "replay did not draw every force sample",
    )
    check(
        replay_plots.is_recording_source() and replay_plots.mode() == "browse",
        "the charts do not browse the recording",
    )
    check(
        replay_plots.mode_label.text() == t("chart.mode_replay"),
        f"the charts do not say they are replaying: {replay_plots.mode_label.text()!r}",
    )
    check(
        not replay_plots.btn_latest.isEnabled(),
        "a recording offers 'back to latest'",
    )

    # The chart cursor is the playhead, and the transport moves it at 1x.
    check(
        replay_window.toolbar.run_role() == "playback",
        "the rail's primary button is not the replay's transport",
    )
    check(replay_window.toolbar.btn_run.isEnabled(), "the replay has no transport")
    check(
        not replay_window.toolbar.btn_run.isChecked(),
        "the replay starts while playing",
    )
    check(
        replay_window.toolbar.btn_run.text() == t("toolbar.playback"),
        f"the button does not say it plays: {replay_window.toolbar.btn_run.text()!r}",
    )
    replay_window.toolbar.btn_run.setChecked(True)
    app.processEvents()
    check(
        replay_window.toolbar.btn_run.text() == t("toolbar.playback_pause"),
        f"the button does not offer pause: {replay_window.toolbar.btn_run.text()!r}",
    )
    started = time.perf_counter()
    for _ in range(12):
        app.processEvents()
        time.sleep(0.03)
    elapsed = time.perf_counter() - started
    replay_window.toolbar.btn_run.setChecked(False)
    app.processEvents()
    check(
        replay.position() > 0.05,
        f"the transport did not advance the playhead: {replay.position()}",
    )
    check(
        replay.position() <= elapsed + 0.2,
        f"the playhead ran ahead of the clock: {replay.position()} > {elapsed}",
    )
    check(
        abs(float(replay_plots.cursors[0].value()) - replay.position()) < 0.05,
        "the chart cursor did not follow the transport",
    )
    check(
        not replay_window.toolbar.btn_run.isChecked(),
        "the transport stayed checked after pause",
    )
    # A manual gesture on the timeline takes over: playback pauses.
    replay_window.toolbar.btn_run.setChecked(True)
    app.processEvents()
    replay_plots.cursors[0].setValue(0.25)
    app.processEvents()
    check(
        not replay_window.toolbar.btn_run.isChecked(),
        "dragging the cursor did not pause the playback",
    )
    check(
        abs(replay.position() - 0.25) < 0.05,
        f"dragging the chart cursor did not scrub the replay: {replay.position()}",
    )
    check(
        replay.video_image() is not None,
        "no video frame was rendered at the cursor position",
    )
    check(
        replay_window.arrow_panel.view_modes() == ("recorded",),
        "the 2D panel still offers the live-only views while replaying",
    )

    # Long-history browsing: an interval read is bounded by the interval, and the
    # whole-session envelope is a band rather than every row.
    from orisys_app_shared.force.source import RecordingCurveSource
    from orisys_app_shared.record.index import RecordingIndex
    from orisys_app_shared.record.playback import RecordingReader as _RecordingReader

    reader = _RecordingReader(recording, max_rows=10)
    source = RecordingCurveSource(reader)
    check(source.kind == "disk", "the replay source is not the recording")
    index = reader.index()
    check(index.rows == 40, f"the index found {index.rows} rows, not 40")
    start, stop = index.row_range(0.5, 1.0)
    check(
        0 <= start < stop <= index.rows and (stop - start) <= 20,
        f"an interval read spans {stop - start} rows",
    )
    interval = source.window(0.5, 1.0, unit="N")
    check(0 < len(interval) <= 20, f"the interval read returned {len(interval)} rows")
    envelope = source.envelope(buckets=8, unit="N")
    check(0 < len(envelope) <= 8, f"the envelope has {len(envelope)} points")
    check(
        reader.info().total_rows == 40,
        f"the recording reports {reader.info().total_rows} rows",
    )
    check(
        t("playback.warn_config_changed").split("{")[0].strip()[:4]
        in replay.warnings_text(),
        f"the replay notes are missing: {replay.warnings_text()!r}",
    )
    check(
        t("playback.warn_config_changed").split("{")[0].strip()[:4]
        in replay_window.toolbar.source_summary.toolTip(),
        f"the replay notes are not reachable from the rail: "
        f"{replay_window.toolbar.source_summary.toolTip()!r}",
    )

    moved: list[float] = []
    replay.position_changed.connect(moved.append)
    replay.set_position(1.0)
    app.processEvents()
    check(
        [round(line.value(), 2) for line in replay_plots.cursors] == [1.0, 1.0, 1.0],
        "the replay cursor is not shared across the three charts",
    )
    check(moved == [1.0], f"the cursor signal did not fire once: {moved}")
    check(
        abs(replay_plots.cursor_time() - 1.0) < 0.05,
        f"the chart cursor did not follow a programmatic position: "
        f"{replay_plots.cursor_time()}",
    )

    # The chart's unit chip rebuilds the recording's curves, not the live ones.
    replay_plots.unit_badge.click()
    app.processEvents()
    check(
        replay.unit() == "N" and replay_plots._unit == "N",
        f"the unit chip did not reach the replay: {replay.unit()}",
    )

    # Playing means decoding a frame per tick. Reopening and seeking the file for
    # every frame (10 ms for a small clip, hundreds for 1080p H.264) is what made
    # the video stand still; the reader keeps one decoder open and steps it.
    span = max(0.1, replay.duration_s() - 0.05)
    seeks: list[float] = []
    for fraction in (0.0, 0.25, 0.5, 0.75, 1.0):
        moment = fraction * span
        started_at = time.perf_counter()
        frame_image, _frame = replay.reader().video_frame_at(moment)
        seeks.append((time.perf_counter() - started_at) * 1000.0)
        check(frame_image is not None, f"no frame at {moment:.2f}s")
    check(
        max(seeks) < 250.0,
        f"a seek costs {max(seeks):.0f} ms, so playback would stall",
    )
    steps: list[float] = []
    for index in range(1, 8):
        started_at = time.perf_counter()
        replay.reader().video_frame_at(index / 30.0)
        steps.append((time.perf_counter() - started_at) * 1000.0)
    check(
        max(steps) < 60.0,
        f"stepping one frame costs {max(steps):.0f} ms, so 30 fps cannot hold",
    )

    # There is no depth recomputation any more: the engine was deleted with
    # the replay bar (depth is not stored with a recording, and the replay
    # view shows the recorded frames). The arrow panel in the replay view
    # therefore offers the recorded image and nothing else.
    check(
        replay_window.arrow_panel.view_modes() == ("recorded",),
        f"the replay still offers a depth pane: "
        f"{replay_window.arrow_panel.view_modes()}",
    )

    # The recompute mode: off (default) the charts read the recorded CSV; on, the
    # recorded video is run through the pipeline instead. The run itself is not
    # started here (that needs the SDK), only the wiring around it.
    started: list = []
    replay_window._start_run = lambda: started.append(True)
    replay_window.act_recompute.setChecked(True)
    for _ in range(3):
        app.processEvents()
    check(
        started == [True],
        "the recompute mode did not hand the video to the pipeline",
    )
    check(
        not replay_plots.is_recording_source(),
        "the charts still read the CSV while recomputing",
    )
    check(
        replay_window.toolbar.source_mode() == "video"
        and replay_window.toolbar.video_path().endswith(".mp4"),
        f"the recompute mode did not select the video: "
        f"{replay_window.toolbar.source_mode()!r} / "
        f"{replay_window.toolbar.video_path()!r}",
    )
    replay_window._recompute_running = True
    replay_window.act_recompute.setChecked(False)
    for _ in range(3):
        app.processEvents()
    check(
        replay_plots.is_recording_source(),
        "turning the recompute off did not restore the recorded curves",
    )
    check(
        replay_window.toolbar.source_mode() == "camera" or not replay_window._running,
        "the recompute pass was left running",
    )

    # Leaving the replay view returns the charts to the live session and hides
    # the bar: the replay stays available, it just stops being on screen.
    check(
        replay_window._load_recording(recording),
        "the replay view could not be re-opened",
    )
    app.processEvents()
    replay_window.brand_bar.btn_live.click()
    app.processEvents()
    check(
        not replay_plots.is_recording_source() and replay_plots.mode() == "follow",
        "leaving the replay view did not restore the live charts",
    )
    check(
        replay_window.toolbar.run_role() != "playback",
        "the rail kept the replay's transport in the live view",
    )
    check(
        not replay_window.toolbar.source_summary.text().endswith(".mp4")
        and "raw_0001" not in replay_window.toolbar.source_summary.text(),
        f"the replay's video is still named in the live view: "
        f"{replay_window.toolbar.source_summary.text()!r}",
    )
    check(
        replay_window.arrow_panel.view_modes() == ("arrows_pure", "arrows_stitched", "depth"),
        "the 2D panel did not return to its live views",
    )
    check(
        replay_window.replay.is_loaded(),
        "leaving the view dropped the open recording",
    )

    # The replay engine is inside the shell now: there is no second window.
    check(
        not hasattr(replay_window, "_playback"),
        "the window still keeps a replay dialog reference",
    )
    check(
        not hasattr(replay_window, "_open_playback"),
        "the window still opens a separate replay window",
    )

    replay_window.replay.close()
    replay_window.close()
    app.processEvents()

    _shutil.rmtree(replay_root, ignore_errors=True)

    print(f"\nscenes: {scene_count}   checks: {CHECKS}   failures: {len(FAILURES)}")
    for failure in FAILURES:
        print(f"  FAIL: {failure}")
    return 1 if FAILURES else 0


if __name__ == "__main__":
    raise SystemExit(main())