booru-viewer/booru_viewer/gui/popout/window.py

"""Popout fullscreen media viewer window."""

from __future__ import annotations

import logging
from pathlib import Path

from PySide6.QtCore import Qt, QEventLoop, QRect, QTimer, Signal
from PySide6.QtGui import QPixmap
from PySide6.QtWidgets import (
    QHBoxLayout, QInputDialog, QLabel, QMainWindow, QMenu, QPushButton,
    QStackedWidget, QVBoxLayout, QWidget,
)

from ..media.constants import _is_video
from ..media.image_viewer import ImageViewer
from ..media.video_player import VideoPlayer
from . import hyprland
from .effects import (
    ApplyLoopMode,
    ApplyMute,
    ApplyVolume,
    EmitClosed,
    EmitNavigate,
    EmitPlayNextRequested,
    EnterFullscreen,
    ExitFullscreen,
    FitWindowToContent,
    LoadImage,
    LoadVideo,
    SeekVideoTo,
    StopMedia,
    TogglePlay,
)
from .state import (
    CloseRequested,
    ContentArrived,
    FullscreenToggled,
    LoopMode,
    LoopModeSet,
    MediaKind,
    MuteToggleRequested,
    NavigateRequested,
    Open,
    SeekCompleted,
    SeekRequested,
    State,
    StateMachine,
    TogglePlayRequested,
    VideoEofReached,
    VideoSizeKnown,
    VideoStarted,
    VolumeSet,
    WindowMoved,
    WindowResized,
)
from .viewport import Viewport, _DRIFT_TOLERANCE, anchor_point


# Adapter logger — separate from the popout's main `booru` logger so
# the dispatch trace can be filtered independently. Format: every
# dispatch call logs at DEBUG with the event name, state transition,
# and effect list. The user filters by `POPOUT_FSM` substring to see
# only the state machine activity during the manual sweep.
#
# The booru logger (parent) only has the in-app QTextEdit LogHandler
# attached (see main_window.py:436-440), so propagating to it routes
# the dispatch trace to the Ctrl+L log panel — useful but invisible
# from the shell. We additionally attach a stderr StreamHandler to
# the adapter logger so `python -m booru_viewer.main_gui 2>&1 |
# grep POPOUT_FSM` works from the terminal. The handler is tagged
# with a sentinel attribute so re-imports don't stack duplicates.
import sys as _sys
_fsm_log = logging.getLogger("booru.popout.adapter")
_fsm_log.setLevel(logging.DEBUG)
if not any(
    getattr(h, "_is_popout_fsm_stderr", False) for h in _fsm_log.handlers
):
    _stderr_handler = logging.StreamHandler(_sys.stderr)
    _stderr_handler.setLevel(logging.DEBUG)
    _stderr_handler.setFormatter(
        logging.Formatter(
            "[%(asctime)s.%(msecs)03d] %(message)s",
            datefmt="%H:%M:%S",
        )
    )
    _stderr_handler._is_popout_fsm_stderr = True
    _fsm_log.addHandler(_stderr_handler)


## Overlay styling for the popout's translucent toolbar / controls bar
## now lives in the bundled themes (themes/*.qss). The widgets get their
## object names set in code (FullscreenPreview / VideoPlayer) so theme QSS
## rules can target them via #_slideshow_toolbar / #_slideshow_controls /
## #_preview_controls. Users can override the look by editing the
## overlay_bg slot in their @palette block, or by adding more specific
## QSS rules in their custom.qss.


class FullscreenPreview(QMainWindow):
    """Fullscreen media viewer with navigation — images, GIFs, and video."""

    navigate = Signal(int)  # direction: -1/+1 for left/right, -cols/+cols for up/down
    play_next_requested = Signal()  # video ended in "Next" mode (wrap-aware)
    bookmark_requested = Signal()
    # Bookmark-as: emitted when the popout's Bookmark button submenu picks
    # a bookmark folder. Empty string = Unfiled. Mirrors ImagePreview's
    # signal so app.py routes both through _bookmark_to_folder_from_preview.
    bookmark_to_folder = Signal(str)
    # Save-to-library: same signal pair as ImagePreview so app.py reuses
    # _save_from_preview / _unsave_from_preview for both. Empty string =
    # Unfiled (root of saved_dir).
    save_to_folder = Signal(str)
    unsave_requested = Signal()
    toggle_save_requested = Signal()
    blacklist_tag_requested = Signal(str)  # tag name
    blacklist_post_requested = Signal()
    open_in_default = Signal()
    open_in_browser = Signal()
    privacy_requested = Signal()
    closed = Signal()

    def __init__(self, grid_cols: int = 3, show_actions: bool = True, monitor: str = "", anchor: str = "center", parent=None) -> None:
        super().__init__(parent, Qt.WindowType.Window)
        self.setWindowTitle("booru-viewer — Popout")
        self._grid_cols = grid_cols
        self._anchor = anchor

        # Central widget — media fills the entire window
        central = QWidget()
        central.setLayout(QVBoxLayout())
        central.layout().setContentsMargins(0, 0, 0, 0)
        central.layout().setSpacing(0)
        self.setContextMenuPolicy(Qt.ContextMenuPolicy.CustomContextMenu)
        self.customContextMenuRequested.connect(self._on_context_menu)

        # Media stack (fills entire window)
        self._stack = QStackedWidget()
        central.layout().addWidget(self._stack)

        self._vol_scroll_accum = 0

        self._viewer = ImageViewer()
        self._viewer.close_requested.connect(self.close)
        self._stack.addWidget(self._viewer)

        self._video = VideoPlayer()
        # Two legacy VideoPlayer forwarding connections were removed
        # during the state machine extraction — don't reintroduce:
        #
        # - `self._video.play_next.connect(self.play_next_requested)`:
        #   the EmitPlayNextRequested effect emits play_next_requested
        #   via the state machine dispatch path. Keeping the forward
        #   would double-emit on every video EOF in Loop=Next mode.
        #
        # - `self._video.video_size.connect(self._on_video_size)`:
        #   the dispatch path's VideoSizeKnown handler produces
        #   FitWindowToContent which the apply path delegates to
        #   _fit_to_content. The direct forwarding was a parallel
        #   duplicate that same-rect-skip in _fit_to_content masked
        #   but that muddied the dispatch trace.
        self._stack.addWidget(self._video)

        self.setCentralWidget(central)

        # Floating toolbar — overlays on top of media, translucent.
        # Set the object name BEFORE the widget is polished by Qt so that
        # the bundled-theme `QWidget#_slideshow_toolbar` selector matches
        # on the very first style computation. Setting it later requires
        # an explicit unpolish/polish cycle, which we want to avoid.
        self._toolbar = QWidget(central)
        self._toolbar.setObjectName("_slideshow_toolbar")
        # Plain QWidget ignores QSS `background:` declarations unless this
        # attribute is set — without it the toolbar paints transparently
        # and the popout buttons sit on bare letterbox color.
        self._toolbar.setAttribute(Qt.WidgetAttribute.WA_StyledBackground, True)
        toolbar = QHBoxLayout(self._toolbar)
        toolbar.setContentsMargins(8, 4, 8, 4)

        # Same compact-padding override as the embedded preview toolbar —
        # Bookmark folders for the popout's Bookmark-as submenu — wired
        # by app.py via set_bookmark_folders_callback after construction.
        self._bookmark_folders_callback = None
        self._is_bookmarked = False
        # Library folders for the popout's Save-to-Library submenu —
        # wired by app.py via set_folders_callback. Same shape as the
        # bookmark folders callback above; library and bookmark folders
        # are independent name spaces and need separate callbacks.
        self._folders_callback = None

        _tb_sz = 24

        def _icon_btn(text: str, name: str, tip: str) -> QPushButton:
            btn = QPushButton(text)
            btn.setObjectName(name)
            btn.setFixedSize(_tb_sz, _tb_sz)
            btn.setToolTip(tip)
            return btn

        self._bookmark_btn = _icon_btn("\u2606", "_tb_bookmark", "Bookmark (B)")
        self._bookmark_btn.clicked.connect(self._on_bookmark_clicked)
        toolbar.addWidget(self._bookmark_btn)

        self._save_btn = _icon_btn("\u2193", "_tb_save", "Save to library (S)")
        self._save_btn.clicked.connect(self._on_save_clicked)
        toolbar.addWidget(self._save_btn)
        self._is_saved = False

        self._bl_tag_btn = _icon_btn("\u2298", "_tb_bl_tag", "Blacklist a tag")
        self._bl_tag_btn.clicked.connect(self._show_bl_tag_menu)
        toolbar.addWidget(self._bl_tag_btn)

        self._bl_post_btn = _icon_btn("\u2297", "_tb_bl_post", "Blacklist this post")
        self._bl_post_btn.clicked.connect(self.blacklist_post_requested)
        toolbar.addWidget(self._bl_post_btn)

        if not show_actions:
            # Library mode: only the Save button stays — it acts as
            # Unsave for the file currently being viewed. Bookmark and
            # blacklist actions are meaningless on already-saved local
            # files (no site/post id to bookmark, no search to filter).
            self._bookmark_btn.hide()
            self._bl_tag_btn.hide()
            self._bl_post_btn.hide()

        toolbar.addStretch()

        self._info_label = QLabel()  # kept for API compat but hidden in slideshow
        self._info_label.hide()

        self._toolbar.raise_()

        # Reparent video controls bar to central widget so it overlays properly.
        # The translucent overlay styling (background, transparent buttons,
        # white-on-dark text) lives in the bundled themes — see the
        # `Popout overlay bars` section of any themes/*.qss. The object names
        # are what those rules target.
        #
        # The toolbar's object name is set above, in its constructor block,
        # so the first style poll picks it up. The controls bar was already
        # polished as a child of VideoPlayer before being reparented here,
        # so we have to force an unpolish/polish round-trip after setting
        # its object name to make Qt re-evaluate the style with the new
        # `#_slideshow_controls` selector.
        self._video._controls_bar.setParent(central)
        self._video._controls_bar.setObjectName("_slideshow_controls")
        # Same fix as the toolbar above — plain QWidget needs this attribute
        # for the QSS `background: ${overlay_bg}` rule to render.
        self._video._controls_bar.setAttribute(Qt.WidgetAttribute.WA_StyledBackground, True)
        cb_style = self._video._controls_bar.style()
        cb_style.unpolish(self._video._controls_bar)
        cb_style.polish(self._video._controls_bar)
        # Same trick on the toolbar — it might have been polished by the
        # central widget's parent before our object name took effect.
        tb_style = self._toolbar.style()
        tb_style.unpolish(self._toolbar)
        tb_style.polish(self._toolbar)
        self._video._controls_bar.raise_()
        self._toolbar.raise_()

        # Privacy overlay — black QWidget child of central, raised over
        # the media stack on privacy_hide. Lives inside the popout
        # itself instead of forcing main_window to hide() the popout
        # window — Wayland's hide→show round-trip drops position because
        # the compositor unmaps and remaps, and Hyprland may re-tile the
        # remap depending on window rules. Keeping the popout mapped
        # with an in-place overlay sidesteps both issues.
        self._privacy_overlay = QWidget(central)
        self._privacy_overlay.setStyleSheet("background: black;")
        self._privacy_overlay.hide()

        # Auto-hide timer for overlay UI
        self._ui_visible = True
        self._hide_timer = QTimer(self)
        self._hide_timer.setSingleShot(True)
        self._hide_timer.setInterval(2000)
        self._hide_timer.timeout.connect(self._hide_overlay)
        self._hide_timer.start()
        self.setMouseTracking(True)
        central.setMouseTracking(True)
        self._stack.setMouseTracking(True)

        from PySide6.QtWidgets import QApplication
        app = QApplication.instance()
        if app is not None:
            app.installEventFilter(self)
        # Pick target monitor
        target_screen = None
        if monitor and monitor != "Same as app":
            for screen in QApplication.screens():
                label = f"{screen.name()} ({screen.size().width()}x{screen.size().height()})"
                if label == monitor:
                    target_screen = screen
                    break
        if not target_screen and parent and parent.screen():
            target_screen = parent.screen()
        if target_screen:
            self.setScreen(target_screen)
            self.setGeometry(target_screen.geometry())
        self._adjusting = False
        # Position-restore handshake: setGeometry below seeds Qt with the saved
        # size, but Hyprland ignores the position for child windows. The first
        # _fit_to_content call after show() picks up _pending_position_restore
        # and corrects the position via a hyprctl batch (no race with the
        # resize). After that first fit, navigation center-pins from whatever
        # position the user has dragged the window to.
        self._first_fit_pending = True
        self._pending_position_restore: tuple[int, int] | None = None
        self._pending_size: tuple[int, int] | None = None
        # Persistent viewport — the user's intent for popout center + size.
        # Seeded from `_pending_size` + `_pending_position_restore` on the
        # first fit after open or F11 exit. Updated only by user action
        # (external drag/resize detected via cur-vs-last-dispatched
        # comparison on Hyprland, or via moveEvent/resizeEvent on
        # non-Hyprland). Navigation between posts NEVER writes to it —
        # `_derive_viewport_for_fit` returns it unchanged unless drift
        # has exceeded `_DRIFT_TOLERANCE`. This is what stops the
        # sub-pixel accumulation that the recompute-from-current-state
        # shortcut couldn't avoid.
        self._viewport: Viewport | None = None
        # Last (x, y, w, h) we dispatched to Hyprland (or to setGeometry
        # on non-Hyprland). Used to detect external moves: if the next
        # nav reads a current rect that differs by more than
        # _DRIFT_TOLERANCE, the user moved or resized the window
        # externally and we adopt the new state as the viewport's intent.
        self._last_dispatched_rect: tuple[int, int, int, int] | None = None
        # Reentrancy guard — set to True around every dispatch so the
        # moveEvent/resizeEvent handlers (which fire on the non-Hyprland
        # Qt fallback path) skip viewport updates triggered by our own
        # programmatic geometry changes.
        self._applying_dispatch: bool = False
        # Stashed content dims from the tiled early-return in
        # _fit_to_content. When the user un-tiles the window, resizeEvent
        # fires — the debounce timer re-runs _fit_to_content with these
        # dims so the floating window gets the correct aspect ratio.
        self._tiled_pending_content: tuple[int, int] | None = None
        self._untile_refit_timer = QTimer(self)
        self._untile_refit_timer.setSingleShot(True)
        self._untile_refit_timer.setInterval(50)
        self._untile_refit_timer.timeout.connect(self._check_untile_refit)
        # Last known windowed geometry — captured on entering fullscreen so
        # F11 → windowed can land back on the same spot. Seeded from saved
        # geometry when the popout opens windowed, so even an immediate
        # F11 → fullscreen → F11 has a sensible target.
        self._windowed_geometry = None
        # Restore saved state or start fullscreen
        if FullscreenPreview._saved_tiled and not FullscreenPreview._saved_fullscreen:
            # Was tiled at last close — let Hyprland's layout place it,
            # then dispatch `settiled` to override the windowrule's float.
            # Saved geometry is meaningless for a tiled window, so skip
            # setGeometry entirely.
            self.show()
            QTimer.singleShot(
                50, lambda: hyprland.settiled(self.windowTitle())
            )
        elif FullscreenPreview._saved_geometry and not FullscreenPreview._saved_fullscreen:
            self.setGeometry(FullscreenPreview._saved_geometry)
            self._pending_position_restore = (
                FullscreenPreview._saved_geometry.x(),
                FullscreenPreview._saved_geometry.y(),
            )
            self._pending_size = (
                FullscreenPreview._saved_geometry.width(),
                FullscreenPreview._saved_geometry.height(),
            )
            self._windowed_geometry = FullscreenPreview._saved_geometry
            self.show()
        else:
            self.showFullScreen()

        # ---- State machine adapter wiring ----
        # Construct the pure-Python state machine and dispatch the
        # initial Open event with the cross-popout-session class state
        # the legacy code stashed above. Every Qt event handler, mpv
        # signal, and button click below dispatches a state machine
        # event via `_dispatch_and_apply`, which applies the returned
        # effects to widgets. The state machine is the authority for
        # "what to do next"; the imperative helpers below are the
        # implementation the apply path delegates into.
        #
        # The grid_cols field is used by the keyboard nav handlers
        # for the Up/Down ±cols stride.
        self._state_machine = StateMachine()
        self._state_machine.grid_cols = grid_cols
        saved_geo_tuple = None
        if FullscreenPreview._saved_geometry:
            sg = FullscreenPreview._saved_geometry
            saved_geo_tuple = (sg.x(), sg.y(), sg.width(), sg.height())
        # Open's handler returns [] (just stashes saved_geo on the
        # state machine) but using _dispatch_and_apply for consistency
        # — every dispatch site goes through one helper.
        self._dispatch_and_apply(Open(
            saved_geo=saved_geo_tuple,
            saved_fullscreen=bool(FullscreenPreview._saved_fullscreen),
            monitor=monitor,
        ))

        # Wire VideoPlayer's playback_restart Signal to the adapter's
        # dispatch routing. mpv emits playback-restart once after each
        # loadfile and once after each completed seek; the adapter
        # distinguishes by checking the state machine's current state
        # at dispatch time.
        self._video.playback_restart.connect(self._on_video_playback_restart)
        # Wire VideoPlayer signals to dispatch+apply via the
        # _dispatch_and_apply helper. Every lambda below MUST call
        # _dispatch_and_apply, not _fsm_dispatch directly — see the
        # docstring on _dispatch_and_apply for the historical bug that
        # explains the distinction.
        self._video.play_next.connect(
            lambda: self._dispatch_and_apply(VideoEofReached())
        )
        self._video.video_size.connect(
            lambda w, h: self._dispatch_and_apply(VideoSizeKnown(width=w, height=h))
        )
        self._video._seek_slider.clicked_position.connect(
            lambda v: self._dispatch_and_apply(SeekRequested(target_ms=v))
        )
        self._video._mute_btn.clicked.connect(
            lambda: self._dispatch_and_apply(MuteToggleRequested())
        )
        self._video._vol_slider.valueChanged.connect(
            lambda v: self._dispatch_and_apply(VolumeSet(value=v))
        )
        self._video._loop_btn.clicked.connect(
            lambda: self._dispatch_and_apply(
                LoopModeSet(mode=LoopMode(self._video.loop_state))
            )
        )

    def _dispatch_and_apply(self, event) -> None:
        """Dispatch an event and apply the returned effects.

        Centralizes the dispatch+apply pattern that every event
        wire-point in the adapter follows. Replaces the older
        `effects = self._fsm_dispatch(...); self._apply_effects(effects)`
        two-line pattern in eventFilter and the bare `_fsm_dispatch`
        calls in the signal connection lambdas.

        Note the historical bug this method exists to prevent: if a
        signal lambda only calls `_fsm_dispatch` (which dispatches
        and logs but does NOT apply effects), the state machine's
        returned effects never reach widgets. That's how commit 14b
        broke video auto-fit and Loop=Next play_next without anyone
        noticing — the lambdas in __init__ were dispatching cleanly
        but the FitWindowToContent and EmitPlayNextRequested effects
        they produced were silently dropped. Going through this
        helper makes the apply step impossible to forget.
        """
        effects = self._fsm_dispatch(event)
        self._apply_effects(effects)

    def _fsm_dispatch(self, event) -> list:
        """Dispatch an event to the state machine and log the result.

        Adapter-internal helper. Centralizes the dispatch + log path
        so every wire-point is one line. Returns the effect list for
        callers that want to inspect it; prefer `_dispatch_and_apply`
        at wire-points so the apply step can't be forgotten.

        The hasattr guard handles edge cases where Qt events might
        fire during __init__ (e.g. resizeEvent on the first show())
        before the state machine has been constructed. After
        construction the guard is always True.
        """
        if not hasattr(self, "_state_machine"):
            return []
        old_state = self._state_machine.state
        effects = self._state_machine.dispatch(event)
        new_state = self._state_machine.state
        _fsm_log.debug(
            "POPOUT_FSM %s | %s -> %s | effects=%s",
            type(event).__name__,
            old_state.name,
            new_state.name,
            [type(e).__name__ for e in effects],
        )
        return effects

    def _on_video_playback_restart(self) -> None:
        """mpv `playback-restart` event arrived via VideoPlayer's
        playback_restart Signal. Distinguish VideoStarted (after load)
        from SeekCompleted (after seek) by the state machine's current
        state.

        This is the ONE place the adapter peeks at state to choose an
        event type — it's a read, not a write, and it's the price of
        having a single mpv event mean two different things.
        """
        if not hasattr(self, "_state_machine"):
            return
        if self._state_machine.state == State.LOADING_VIDEO:
            self._dispatch_and_apply(VideoStarted())
        elif self._state_machine.state == State.SEEKING_VIDEO:
            self._dispatch_and_apply(SeekCompleted())
        # Other states: drop. The state machine's release-mode
        # legality check would also drop it; this saves the dispatch
        # round trip.

    # ------------------------------------------------------------------
    # Effect application
    # ------------------------------------------------------------------
    #
    # The state machine's dispatch returns a list of Effect descriptors
    # describing what the adapter should do. `_apply_effects` is the
    # single dispatch point: `_dispatch_and_apply` dispatches then calls
    # this. The pattern-match by type is the architectural choke point
    # — a new Effect type in state.py triggers the TypeError branch at
    # runtime instead of silently dropping the effect.
    #
    # A few apply handlers are intentional no-ops:
    #
    # - ApplyMute / ApplyVolume / ApplyLoopMode: the legacy slot
    #   connections on the popout's VideoPlayer handle the user-facing
    #   toggles directly. The state machine tracks these values as the
    #   source of truth for sync with the embedded preview; pushing
    #   them back here would create a double-write hazard.
    #
    # - SeekVideoTo: `_ClickSeekSlider.clicked_position → _seek` on the
    #   VideoPlayer handles both the mpv.seek call and the legacy
    #   500ms pin window. The state machine's SeekingVideo state
    #   tracks the seek; the slider rendering and the seek call itself
    #   live on VideoPlayer.
    #
    # Every other effect (LoadImage, LoadVideo, StopMedia,
    # FitWindowToContent, EnterFullscreen, ExitFullscreen,
    # EmitNavigate, EmitPlayNextRequested, EmitClosed, TogglePlay)
    # delegates to a private helper in this file. The state machine
    # is the entry point; the helpers are the implementation.

    def _apply_effects(self, effects: list) -> None:
        """Apply a list of Effect descriptors returned by dispatch.

        Pattern-matches each effect to its apply handler. Unknown
        effect types raise TypeError so the next added effect type
        in state.py is caught at runtime instead of silently dropped.
        """
        for e in effects:
            if isinstance(e, LoadImage):
                self._apply_load_image(e)
            elif isinstance(e, LoadVideo):
                self._apply_load_video(e)
            elif isinstance(e, StopMedia):
                self._apply_stop_media()
            elif isinstance(e, ApplyMute):
                # No-op — VideoPlayer's legacy slot owns widget update;
                # the state machine keeps state.mute as the sync source
                # for the embedded-preview path.
                pass
            elif isinstance(e, ApplyVolume):
                pass  # same — widget update handled by VideoPlayer
            elif isinstance(e, ApplyLoopMode):
                pass  # same — widget update handled by VideoPlayer
            elif isinstance(e, SeekVideoTo):
                # No-op — `_seek` slot on VideoPlayer handles both
                # mpv.seek and the pin window. The state's SeekingVideo
                # fields exist so the slider's read-path still returns
                # the clicked position during the seek.
                pass
            elif isinstance(e, TogglePlay):
                self._video._toggle_play()
            elif isinstance(e, FitWindowToContent):
                self._fit_to_content(e.content_w, e.content_h)
            elif isinstance(e, EnterFullscreen):
                self._enter_fullscreen()
            elif isinstance(e, ExitFullscreen):
                self._exit_fullscreen()
            elif isinstance(e, EmitNavigate):
                self.navigate.emit(e.direction)
            elif isinstance(e, EmitPlayNextRequested):
                self.play_next_requested.emit()
            elif isinstance(e, EmitClosed):
                self.closed.emit()
            else:
                raise TypeError(
                    f"Unknown effect type: {type(e).__name__}. "
                    f"Add a handler in _apply_effects."
                )

    def _apply_load_image(self, e: LoadImage) -> None:
        """Apply LoadImage effect — display a static image or GIF.

        Mirrors the legacy `set_media` body's image branch. Stops
        any active video and clears its controls bar before swapping
        in the image. The fit comes from a separate FitWindowToContent
        effect that the state machine emits alongside LoadImage.
        """
        info = self._state_machine.current_info
        self._video.stop()
        self._video._controls_bar.hide()
        if e.is_gif:
            self._viewer.set_gif(e.path, info)
        else:
            pix = QPixmap(e.path)
            if not pix.isNull():
                self._viewer.set_image(pix, info)
        self._stack.setCurrentIndex(0)

    def _apply_load_video(self, e: LoadVideo) -> None:
        """Apply LoadVideo effect — hand the path or URL to mpv.

        Stack switch happens FIRST so the video surface is visible
        the moment mpv produces its first frame. clear() releases the
        previous image (now hidden behind the video surface). No
        explicit stop() — loadfile("replace") atomically replaces the
        current file without the eof side-effect of command('stop').
        """
        self._stack.setCurrentIndex(1)
        self._viewer.clear()
        self._video.play_file(e.path, e.info)

    def _apply_stop_media(self) -> None:
        """Apply StopMedia effect — clear both surfaces.

        Idempotent. Called on navigation away from current media,
        on close, and as part of the StopMedia effect from various
        transitions.
        """
        self._video.stop()
        self._viewer.clear()

    _saved_geometry = None  # remembers window size/position across opens
    _saved_fullscreen = False
    _saved_tiled = False  # True if Hyprland had it tiled at last close
    _current_tags: dict[str, list[str]] = {}
    _current_tag_list: list[str] = []

    def set_post_tags(self, tag_categories: dict[str, list[str]], tag_list: list[str]) -> None:
        self._current_tags = tag_categories
        self._current_tag_list = tag_list

    def _exec_menu_at_button(self, menu: QMenu, btn: QPushButton):
        """Open a menu anchored below a button, blocking until dismissed.

        Uses popup() + QEventLoop instead of exec(pos) because on
        Hyprland/Wayland the popout window gets moved via hyprctl after
        Qt maps it, and Qt's window-position tracking stays stale. Using
        exec(btn.mapToGlobal(...)) resolves to a global point on the
        wrong monitor, causing the menu to flash there before the
        compositor corrects it. popup() routes through the same path
        but with triggered/aboutToHide signals we can block manually.
        """
        result = [None]
        menu.triggered.connect(lambda a: result.__setitem__(0, a))
        loop = QEventLoop()
        menu.aboutToHide.connect(loop.quit)
        menu.popup(btn.mapToGlobal(btn.rect().bottomLeft()))
        loop.exec()
        return result[0]

    def _show_bl_tag_menu(self) -> None:
        menu = QMenu(self)
        if self._current_tags:
            for category, tags in self._current_tags.items():
                cat_menu = menu.addMenu(category)
                for tag in tags[:30]:
                    cat_menu.addAction(tag)
        else:
            for tag in self._current_tag_list[:30]:
                menu.addAction(tag)
        action = self._exec_menu_at_button(menu, self._bl_tag_btn)
        if action:
            self.blacklist_tag_requested.emit(action.text())

    def update_state(self, bookmarked: bool, saved: bool) -> None:
        self._is_bookmarked = bookmarked
        self._bookmark_btn.setText("\u2605" if bookmarked else "\u2606")  # ★ / ☆
        self._bookmark_btn.setToolTip("Unbookmark (B)" if bookmarked else "Bookmark (B)")
        self._is_saved = saved
        self._save_btn.setText("\u2715" if saved else "\u2193")  # ✕ / ⤓
        self._save_btn.setToolTip("Unsave from library" if saved else "Save to library (S)")

    # ------------------------------------------------------------------
    # Public method interface
    # ------------------------------------------------------------------
    #
    # The methods below are the only entry points main_window.py uses
    # to drive the popout. They wrap the private fields so main_window
    # doesn't have to know about VideoPlayer / ImageViewer /
    # QStackedWidget internals. The private fields stay in place; these
    # are clean public wrappers, not a re-architecture.

    def is_video_active(self) -> bool:
        """True if the popout is currently showing a video (vs image).

        Replaces direct `popout._stack.currentIndex() == 1` checks
        from main_window. Used to gate per-tab video-only operations
        (volume scroll, seek, pause).
        """
        return self._stack.currentIndex() == 1

    def set_toolbar_visibility(
        self,
        *,
        bookmark: bool,
        save: bool,
        bl_tag: bool,
        bl_post: bool,
    ) -> None:
        """Per-tab toolbar gating.

        Replaces direct `popout._bookmark_btn.setVisible(...)` etc
        from main_window's `_update_fullscreen` method. Library tab
        hides Bookmark / BL Tag / BL Post (no site/post id to act
        on) but keeps Save (acts as Unsave for the file currently
        being viewed).
        """
        self._bookmark_btn.setVisible(bookmark)
        self._save_btn.setVisible(save)
        self._bl_tag_btn.setVisible(bl_tag)
        self._bl_post_btn.setVisible(bl_post)

    def sync_video_state(
        self,
        *,
        volume: int,
        mute: bool,
        autoplay: bool,
        loop_state: int,
    ) -> None:
        """Push state from the embedded preview into the popout's
        video player.

        Called by main_window's `_open_fullscreen_preview` after the
        popout is constructed. Replaces direct `popout._video.volume
        = ...` etc writes. Uses VideoPlayer's existing setters which
        handle the lazy-mpv pending-state pattern (mute survives
        first-load via _pending_mute, volume survives via the slider
        widget acting as persistent storage).
        """
        self._video.volume = volume
        self._video.is_muted = mute
        self._video.autoplay = autoplay
        self._video.loop_state = loop_state

    def get_video_state(self) -> dict:
        """Read video player state for the reverse sync at popout close.

        Returns a dict with `volume`, `mute`, `autoplay`, `loop_state`,
        and `position_ms` (current playback position in milliseconds,
        0 if the popout isn't currently on the video stack). Called
        by main_window's `_on_fullscreen_closed` to push the state
        back into the embedded preview's video player.
        """
        return {
            "volume": self._video.volume,
            "mute": self._video.is_muted,
            "autoplay": self._video.autoplay,
            "loop_state": self._video.loop_state,
            "position_ms": getattr(self, "_close_position_ms", None) or (
                self._video.get_position_ms()
                if self.is_video_active()
                else 0
            ),
        }

    def seek_video_to(self, ms: int) -> None:
        """Seek the video to a specific position in milliseconds.

        Used by main_window's seek-after-load pattern when restoring
        video position across popout open/close cycles. Wraps
        `VideoPlayer.seek_to_ms` (which uses `'absolute+exact'` for
        frame-accurate landing — same as the slider's `_seek` after
        the 609066c drag-back fix).
        """
        self._video.seek_to_ms(ms)

    def connect_media_ready_once(self, callback) -> None:
        """Wire a one-shot callback to the video player's media_ready
        signal. The callback fires once when the next loaded video
        becomes ready, then disconnects itself.

        Replaces main_window's manual lambda + try/except disconnect
        dance for the seek-when-ready pattern (open popout → wait for
        the new mpv instance to load → restore the embedded preview's
        playback position).
        """
        def _wrapper():
            try:
                callback()
            finally:
                try:
                    self._video.media_ready.disconnect(_wrapper)
                except (TypeError, RuntimeError):
                    pass
        self._video.media_ready.connect(_wrapper)

    def pause_media(self) -> None:
        """Pause the active video player. No-op if no video is loaded.

        Replaces direct `popout._video.pause()` calls from main_window
        in privacy-screen / blacklist / video-end paths. Goes through
        VideoPlayer.pause() which handles the play-button text update
        and respects the lazy-mpv state.
        """
        self._video.pause()

    def force_mpv_pause(self) -> None:
        """Set mpv.pause = True directly without going through Qt
        property setters or button text updates.

        Used by main_window's `_on_post_activated` to prevent the OLD
        video from reaching natural EOF during the new post's async
        download (which would auto-advance past the post the user
        clicked). Different from `pause_media` because this writes
        the mpv property directly — no eof-reached side effect, no
        button text flicker mid-load.

        Replaces the legacy `popout._video._mpv.pause = True` deep
        attribute access from main_window line ~1125. The
        `_mpv is None` guard handles the pre-first-load case where
        `_ensure_mpv` hasn't run yet.
        """
        if self._video._mpv is not None:
            try:
                self._video._mpv.pause = True
            except Exception:
                # mpv was torn down or is mid-transition between
                # files; pause is best-effort so a stale instance
                # rejecting the property write isn't a real failure.
                pass

    def stop_media(self) -> None:
        """Stop the video and clear the image viewer.

        Used by main_window's blacklist-removal flow when the post
        being viewed gets blacklisted. Replaces the
        `popout._viewer.clear() + popout._video.stop()` sequence from
        main_window with a single call.
        """
        self._video.stop()
        self._viewer.clear()

    def set_bookmark_folders_callback(self, callback) -> None:
        """Wire the bookmark folder list source. Called once from app.py
        right after the popout is constructed; matches the embedded
        ImagePreview's set_bookmark_folders_callback shape.
        """
        self._bookmark_folders_callback = callback

    def set_folders_callback(self, callback) -> None:
        """Wire the library folder list source. Called once from app.py
        right after the popout is constructed; matches the embedded
        ImagePreview's set_folders_callback shape.
        """
        self._folders_callback = callback

    def _on_save_clicked(self) -> None:
        """Popout Save button — same shape as the embedded preview's
        version. When already saved, emit unsave_requested for the existing
        unsave path. When not saved, pop a menu under the button with
        Unfiled / library folders / + New Folder, then emit the chosen
        name through save_to_folder. app.py reuses _save_from_preview /
        _unsave_from_preview to handle both signals.
        """
        if self._is_saved:
            self.unsave_requested.emit()
            return
        menu = QMenu(self)
        unfiled = menu.addAction("Unfiled")
        menu.addSeparator()
        folder_actions: dict[int, str] = {}
        if self._folders_callback:
            for folder in self._folders_callback():
                a = menu.addAction(folder)
                folder_actions[id(a)] = folder
        menu.addSeparator()
        new_action = menu.addAction("+ New Folder...")
        action = self._exec_menu_at_button(menu, self._save_btn)
        if not action:
            return
        if action == unfiled:
            self.save_to_folder.emit("")
        elif action == new_action:
            name, ok = QInputDialog.getText(self, "New Folder", "Folder name:")
            if ok and name.strip():
                self.save_to_folder.emit(name.strip())
        elif id(action) in folder_actions:
            self.save_to_folder.emit(folder_actions[id(action)])

    def _on_bookmark_clicked(self) -> None:
        """Popout Bookmark button — same shape as the embedded preview's
        version. When already bookmarked, emits bookmark_requested for the
        existing toggle/remove path. When not bookmarked, pops a menu under
        the button with Unfiled / bookmark folders / + New Folder, then
        emits the chosen name through bookmark_to_folder.
        """
        if self._is_bookmarked:
            self.bookmark_requested.emit()
            return
        menu = QMenu(self)
        unfiled = menu.addAction("Unfiled")
        menu.addSeparator()
        folder_actions: dict[int, str] = {}
        if self._bookmark_folders_callback:
            for folder in self._bookmark_folders_callback():
                a = menu.addAction(folder)
                folder_actions[id(a)] = folder
        menu.addSeparator()
        new_action = menu.addAction("+ New Folder...")
        action = self._exec_menu_at_button(menu, self._bookmark_btn)
        if not action:
            return
        if action == unfiled:
            self.bookmark_to_folder.emit("")
        elif action == new_action:
            name, ok = QInputDialog.getText(self, "New Bookmark Folder", "Folder name:")
            if ok and name.strip():
                self.bookmark_to_folder.emit(name.strip())
        elif id(action) in folder_actions:
            self.bookmark_to_folder.emit(folder_actions[id(action)])

    def _on_context_menu(self, pos) -> None:
        menu = QMenu(self)

        # Bookmark: unbookmark if already bookmarked, folder submenu if not
        fav_action = None
        bm_folder_actions = {}
        bm_new_action = None
        bm_unfiled = None
        if self._is_bookmarked:
            fav_action = menu.addAction("Unbookmark")
        else:
            bm_menu = menu.addMenu("Bookmark as")
            bm_unfiled = bm_menu.addAction("Unfiled")
            bm_menu.addSeparator()
            if self._bookmark_folders_callback:
                for folder in self._bookmark_folders_callback():
                    a = bm_menu.addAction(folder)
                    bm_folder_actions[id(a)] = folder
            bm_menu.addSeparator()
            bm_new_action = bm_menu.addAction("+ New Folder...")

        save_menu = None
        save_unsorted = None
        save_new = None
        save_folder_actions = {}
        unsave_action = None
        if self._is_saved:
            unsave_action = menu.addAction("Unsave from Library")
        else:
            save_menu = menu.addMenu("Save to Library")
            save_unsorted = save_menu.addAction("Unfiled")
            save_menu.addSeparator()
            if self._folders_callback:
                for folder in self._folders_callback():
                    a = save_menu.addAction(folder)
                    save_folder_actions[id(a)] = folder
            save_menu.addSeparator()
            save_new = save_menu.addAction("+ New Folder...")

        menu.addSeparator()
        copy_action = menu.addAction("Copy File to Clipboard")
        copy_url_action = menu.addAction("Copy Image URL")
        open_action = menu.addAction("Open in Default App")
        browser_action = menu.addAction("Open in Browser")

        reset_action = None
        if self._stack.currentIndex() == 0:
            reset_action = menu.addAction("Reset View")

        menu.addSeparator()
        close_action = menu.addAction("Close Popout")

        action = menu.exec(self.mapToGlobal(pos))
        if not action:
            return
        if action == fav_action:
            self.bookmark_requested.emit()
        elif action == bm_unfiled:
            self.bookmark_to_folder.emit("")
        elif action == bm_new_action:
            name, ok = QInputDialog.getText(self, "New Bookmark Folder", "Folder name:")
            if ok and name.strip():
                self.bookmark_to_folder.emit(name.strip())
        elif id(action) in bm_folder_actions:
            self.bookmark_to_folder.emit(bm_folder_actions[id(action)])
        elif action == save_unsorted:
            self.save_to_folder.emit("")
        elif action == save_new:
            name, ok = QInputDialog.getText(self, "New Folder", "Folder name:")
            if ok and name.strip():
                self.save_to_folder.emit(name.strip())
        elif id(action) in save_folder_actions:
            self.save_to_folder.emit(save_folder_actions[id(action)])
        elif action == unsave_action:
            self.unsave_requested.emit()
        elif action == copy_action:
            from pathlib import Path as _Path
            from PySide6.QtCore import QMimeData, QUrl
            from PySide6.QtWidgets import QApplication
            from PySide6.QtGui import QPixmap as _QP
            cp = self._state_machine.current_path
            if cp and cp.startswith(("http://", "https://")):
                from ...core.cache import cached_path_for
                cached = cached_path_for(cp)
                cp = str(cached) if cached.exists() else None
            if cp and _Path(cp).exists():
                mime = QMimeData()
                mime.setUrls([QUrl.fromLocalFile(str(_Path(cp).resolve()))])
                pix = _QP(cp)
                if not pix.isNull():
                    mime.setImageData(pix.toImage())
                QApplication.clipboard().setMimeData(mime)
        elif action == copy_url_action:
            from PySide6.QtWidgets import QApplication
            url = self._state_machine.current_path or ""
            if url:
                QApplication.clipboard().setText(url)
        elif action == open_action:
            self.open_in_default.emit()
        elif action == browser_action:
            self.open_in_browser.emit()
        elif action == reset_action:
            self._viewer._fit_to_view()
            self._viewer.update()
        elif action == close_action:
            self.close()

    def set_media(self, path: str, info: str = "", width: int = 0, height: int = 0) -> None:
        """Display `path` in the popout, info string above it.

        `width` and `height` are the *known* media dimensions from the
        post metadata (booru API), passed in by the caller when
        available. They're used to pre-fit the popout window for video
        files BEFORE mpv has loaded the file, so cached videos don't
        flash a wrong-shaped black surface while mpv decodes the first
        frame. mpv still fires `video_size` after demuxing and the
        second `_fit_to_content` call corrects the aspect if the
        encoded video-params differ from the API metadata (rare —
        anamorphic / weirdly cropped sources). Both fits use the
        persistent viewport's same `long_side` and the same center,
        so the second fit is a no-op in the common case and only
        produces a shape correction (no positional move) in the
        mismatch case.
        """
        self._info_label.setText(info)
        ext = Path(path).suffix.lower()

        # Detect kind for the state machine.
        if _is_video(path):
            kind = MediaKind.VIDEO
        elif ext == ".gif":
            kind = MediaKind.GIF
        else:
            kind = MediaKind.IMAGE
        # Build the per-file referrer for streaming URLs. play_file
        # also computes this internally during the legacy load path,
        # but the dispatch path passes it through ContentArrived for
        # the future when the state machine fully drives the load.
        referer = None
        if path.startswith(("http://", "https://")):
            try:
                from urllib.parse import urlparse
                from ...core.cache import _referer_for
                referer = _referer_for(urlparse(path))
            except Exception:
                _fsm_log.debug(
                    "referer derivation failed for %s", path, exc_info=True,
                )

        # Dispatch + apply. The state machine produces:
        #   - LoadVideo or LoadImage (loads the media)
        #   - FitWindowToContent (delegates to _fit_to_content)
        # Both are applied via _apply_effects which delegates to the
        # private helpers. The state machine becomes the single entry
        # point for media load; set_media's body shrinks to dispatch
        # + apply.
        self._dispatch_and_apply(ContentArrived(
            path=path,
            info=info,
            kind=kind,
            width=width,
            height=height,
            referer=referer,
        ))
        # Note: pre-fit to API dimensions was tried (option A from
        # the perf round) but caused a perceptible slowdown in popout
        # video clicks — the redundant second hyprctl dispatch when
        # mpv's video_size callback fired produced a visible
        # re-settle. The width/height params remain on the signature
        # so the streaming and update-fullscreen call sites can keep
        # passing them, but they're currently ignored. Re-enable
        # cautiously if you can prove the second fit becomes a true
        # no-op.
        _ = (width, height)
        # Note: do NOT auto-show the overlay on every set_media. The
        # overlay should appear in response to user hover (handled in
        # eventFilter on mouse-move into the top/bottom edge zones),
        # not pop back up after every navigation.

    def _is_hypr_floating(self) -> bool | None:
        """Check if this window is floating in Hyprland. None if not on Hyprland."""
        win = hyprland.get_window(self.windowTitle())
        if win is None:
            return None  # not Hyprland
        return bool(win.get("floating"))

    @staticmethod
    def _compute_window_rect(
        viewport: Viewport, content_aspect: float, screen,
        avail_override: tuple[int, int, int, int] | None = None,
    ) -> tuple[int, int, int, int]:
        """Project a viewport onto a window rect for the given content aspect.

        Symmetric across portrait/landscape: a 9:16 portrait and a 16:9
        landscape with the same `long_side` have the same maximum edge
        length. Proportional clamp shrinks both edges by the same factor
        if either would exceed its 0.90-of-screen ceiling, preserving
        aspect exactly. Pure function — no side effects, no widget
        access, all inputs explicit so it's trivial to reason about.

        ``viewport.center_x``/``center_y`` hold the anchor point — the
        window center in ``"center"`` mode, or the pinned corner in
        corner modes. The anchor stays fixed; the window grows/shrinks
        away from it.

        *avail_override* is an (x, y, w, h) tuple that replaces
        ``screen.availableGeometry()`` — used on Hyprland where Qt
        doesn't see Waybar's exclusive zone but ``hyprctl monitors -j``
        reports it via the ``reserved`` array.
        """
        if content_aspect >= 1.0:               # landscape or square
            w = viewport.long_side
            h = viewport.long_side / content_aspect
        else:                                   # portrait
            h = viewport.long_side
            w = viewport.long_side * content_aspect

        if avail_override:
            ax, ay, aw, ah = avail_override
        else:
            _a = screen.availableGeometry()
            ax, ay, aw, ah = _a.x(), _a.y(), _a.width(), _a.height()
        cap_w = aw * 0.90
        cap_h = ah * 0.90
        scale = min(1.0, cap_w / w, cap_h / h)
        w *= scale
        h *= scale

        anchor = viewport.anchor
        if anchor == "tl":
            x = viewport.center_x
            y = viewport.center_y
        elif anchor == "tr":
            x = viewport.center_x - w
            y = viewport.center_y
        elif anchor == "bl":
            x = viewport.center_x
            y = viewport.center_y - h
        elif anchor == "br":
            x = viewport.center_x - w
            y = viewport.center_y - h
        else:
            x = viewport.center_x - w / 2
            y = viewport.center_y - h / 2

        # Nudge onto screen if the window would land off-edge.
        x = max(ax, min(x, ax + aw - w))
        y = max(ay, min(y, ay + ah - h))

        return (round(x), round(y), round(w), round(h))

    def _build_viewport_from_current(
        self, floating: bool | None, win: dict | None = None
    ) -> Viewport | None:
        """Build a viewport from the current window state, no caching.

        Used in two cases:
          1. First fit after open / F11 exit, when the persistent
             `_viewport` is None and we need a starting value (the
             `_pending_*` one-shots feed this path).
          2. The "user moved the window externally" detection branch
             in `_derive_viewport_for_fit`, when the cur-vs-last-dispatched
             comparison shows drift > _DRIFT_TOLERANCE.

        Returns None only if every source fails — Hyprland reports no
        window AND non-Hyprland Qt geometry is also invalid.
        """
        if floating is True:
            if win is None:
                win = hyprland.get_window(self.windowTitle())
            if win and win.get("at") and win.get("size"):
                wx, wy = win["at"]
                ww, wh = win["size"]
                ax, ay = anchor_point(wx, wy, ww, wh, self._anchor)
                return Viewport(
                    center_x=ax, center_y=ay,
                    long_side=float(max(ww, wh)),
                    anchor=self._anchor,
                )
        if floating is None:
            rect = self.geometry()
            if rect.width() > 0 and rect.height() > 0:
                ax, ay = anchor_point(rect.x(), rect.y(), rect.width(), rect.height(), self._anchor)
                return Viewport(
                    center_x=ax, center_y=ay,
                    long_side=float(max(rect.width(), rect.height())),
                    anchor=self._anchor,
                )
        return None

    def _derive_viewport_for_fit(
        self, floating: bool | None, win: dict | None = None
    ) -> Viewport | None:
        """Return the persistent viewport, updating it only on user action.

        Three branches in priority order:

          1. **First fit after open or F11 exit**: the `_pending_*`
             one-shots are set. Seed `_viewport` from them and return.
             This is the only path that overwrites the persistent
             viewport unconditionally.

          2. **Persistent viewport exists and is in agreement with
             current window state**: return it unchanged. The compute
             never reads its own output as input — sub-pixel drift
             cannot accumulate here because we don't observe it.

          3. **Persistent viewport exists but current state differs by
             more than `_DRIFT_TOLERANCE`**: the user moved or resized
             the window externally (Super+drag in Hyprland, corner-resize,
             window manager intervention). Update the viewport from
             current state — the user's new physical position IS the
             new intent.

        Wayland external moves don't fire Qt's `moveEvent`, so branch 3
        is the only mechanism that captures Hyprland Super+drag. The
        `_last_dispatched_rect` cache is what makes branch 2 stable —
        without it, we'd have to read current state and compare to the
        viewport's projection (the same code path that drifts).

        `win` may be passed in by the caller to avoid an extra
        `_hyprctl_get_window()` subprocess call (~3ms saved).
        """
        # Branch 1: first fit after open or F11 exit
        if self._first_fit_pending and self._pending_size and self._pending_position_restore:
            pw, ph = self._pending_size
            px, py = self._pending_position_restore
            ax, ay = anchor_point(px, py, pw, ph, self._anchor)
            self._viewport = Viewport(
                center_x=ax, center_y=ay,
                long_side=float(max(pw, ph)),
                anchor=self._anchor,
            )
            return self._viewport

        # No persistent viewport yet AND no first-fit one-shots — defensive
        # fallback. Build from current state and stash for next call.
        if self._viewport is None:
            self._viewport = self._build_viewport_from_current(floating, win)
            return self._viewport

        # Branch 2/3: persistent viewport exists. Check whether the user
        # moved or resized the window externally since our last dispatch.
        if floating is True and self._last_dispatched_rect is not None:
            if win is None:
                win = hyprland.get_window(self.windowTitle())
            if win and win.get("at") and win.get("size"):
                cur_x, cur_y = win["at"]
                cur_w, cur_h = win["size"]
                last_x, last_y, last_w, last_h = self._last_dispatched_rect
                drift = max(
                    abs(cur_x - last_x),
                    abs(cur_y - last_y),
                    abs(cur_w - last_w),
                    abs(cur_h - last_h),
                )
                if drift > _DRIFT_TOLERANCE:
                    # External move/resize detected. Adopt current as intent.
                    ax, ay = anchor_point(cur_x, cur_y, cur_w, cur_h, self._anchor)
                    self._viewport = Viewport(
                        center_x=ax, center_y=ay,
                        long_side=float(max(cur_w, cur_h)),
                        anchor=self._anchor,
                    )

        return self._viewport

    def _fit_to_content(self, content_w: int, content_h: int, _retry: int = 0) -> None:
        """Size window to fit content. Viewport-based: long_side preserved across navs.

        Distinguishes "not on Hyprland" (Qt drives geometry, no aspect
        lock available) from "on Hyprland but the window isn't visible
        to hyprctl yet" (the very first call after a popout open races
        the wm:openWindow event — `hyprctl clients -j` returns no entry
        for our title for ~tens of ms). The latter case used to fall
        through to a plain Qt resize and skip the keep_aspect_ratio
        setprop entirely, so the *first* image popout always opened
        without aspect locking and only subsequent navigations got the
        right shape. Now we retry with a short backoff when on Hyprland
        and the window isn't found, capped so a real "not Hyprland"
        signal can't loop.

        Math is now viewport-based: a Viewport (center + long_side) is
        derived from current state, then projected onto a rect for the
        new content aspect via `_compute_window_rect`. This breaks the
        width-anchor ratchet that the previous version had — long_side
        is symmetric across portrait and landscape, so navigating
        P→L→P→L doesn't permanently shrink the landscape width.
        See the plan at ~/.claude/plans/ancient-growing-lantern.md
        for the full derivation.
        """
        if self.isFullScreen() or content_w <= 0 or content_h <= 0:
            return
        import os
        on_hypr = bool(os.environ.get("HYPRLAND_INSTANCE_SIGNATURE"))
        # Cache the hyprctl window query — `_hyprctl_get_window()` is a
        # ~3ms subprocess.run call on the GUI thread, and the helpers
        # below would each fire it again if we didn't pass it down.
        # Threading the dict through cuts the per-fit subprocess count
        # from three to one, eliminating ~6ms of UI freeze per navigation.
        win = None
        if on_hypr:
            win = hyprland.get_window(self.windowTitle())
            if win is None:
                if _retry < 5:
                    QTimer.singleShot(
                        40,
                        lambda: self._fit_to_content(content_w, content_h, _retry + 1),
                    )
                return
            floating = bool(win.get("floating"))
        else:
            floating = None
        if floating is False:
            hyprland.resize(self.windowTitle(), 0, 0, animate=self._first_fit_pending)  # tiled: just set keep_aspect_ratio
            self._tiled_pending_content = (content_w, content_h)
            return
        self._tiled_pending_content = None
        aspect = content_w / content_h
        screen = self.screen()
        if screen is None:
            return
        viewport = self._derive_viewport_for_fit(floating, win=win)
        if viewport is None:
            # No source for a viewport (Hyprland reported no window AND
            # Qt geometry is invalid). Bail without dispatching — clearing
            # the one-shots would lose the saved position; leaving them
            # set lets a subsequent fit retry.
            return
        avail_rect = None
        if on_hypr and win:
            avail_rect = hyprland.get_monitor_available_rect(win.get("monitor"))
        x, y, w, h = self._compute_window_rect(viewport, aspect, screen, avail_override=avail_rect)
        # Identical-rect skip. If the computed rect is exactly what
        # we last dispatched, the window is already in that state and
        # there's nothing for hyprctl (or setGeometry) to do. Skipping
        # saves one subprocess.Popen + Hyprland's processing of the
        # redundant resize/move dispatch — ~100-300ms of perceived
        # latency on cached video clicks where the new content has the
        # same aspect/long_side as the previous, which is common (back-
        # to-back videos from the same source, image→video with matching
        # aspect, re-clicking the same post). Doesn't apply on the very
        # first fit after open (last_dispatched_rect is None) and the
        # first dispatch always lands. Doesn't break drift detection
        # because the comparison branch in _derive_viewport_for_fit
        # already ran above and would have updated _viewport (and
        # therefore the computed rect) if Hyprland reported drift.
        if self._last_dispatched_rect == (x, y, w, h):
            self._first_fit_pending = False
            self._pending_position_restore = None
            self._pending_size = None
            return
        # Reentrancy guard: set before any dispatch so the
        # moveEvent/resizeEvent handlers (which fire on the non-Hyprland
        # Qt fallback path) don't update the persistent viewport from
        # our own programmatic geometry change.
        self._applying_dispatch = True
        try:
            if floating is True:
                # Hyprland: hyprctl is the sole authority. Calling self.resize()
                # here would race with the batch below and produce visible flashing
                # when the window also has to move.
                hyprland.resize_and_move(
                    self.windowTitle(), w, h, x, y, win=win,
                    animate=self._first_fit_pending,
                )
            else:
                # Non-Hyprland fallback: Qt drives geometry directly. Use
                # setGeometry with the computed top-left rather than resize()
                # so the window center stays put — Qt's resize() anchors
                # top-left and lets the bottom-right move, which causes the
                # popout center to drift toward the upper-left of the screen
                # over repeated navigations.
                self.setGeometry(QRect(x, y, w, h))
        finally:
            self._applying_dispatch = False
        # Cache the dispatched rect so the next nav can compare current
        # Hyprland state against it and detect external moves/resizes.
        # This is the persistent-viewport's link back to reality without
        # reading our own output every nav.
        self._last_dispatched_rect = (x, y, w, h)
        self._first_fit_pending = False
        self._pending_position_restore = None
        self._pending_size = None

    def _check_untile_refit(self) -> None:
        """Debounced callback: re-run fit if we left tiled under new content."""
        if self._tiled_pending_content is not None:
            cw, ch = self._tiled_pending_content
            self._fit_to_content(cw, ch)
            # Reset image zoom/offset so the image fits the new window
            # geometry cleanly — the viewer's state is stale from the
            # tiled layout.
            if self._stack.currentIndex() == 0:
                self._viewer._fit_to_view()
                self._viewer.update()

    def _show_overlay(self) -> None:
        """Show toolbar and video controls, restart auto-hide timer."""
        if not self._ui_visible:
            self._toolbar.show()
            if self._stack.currentIndex() == 1:
                self._video._controls_bar.show()
            self._ui_visible = True
        self._hide_timer.start()

    def _hide_overlay(self) -> None:
        """Hide toolbar and video controls."""
        self._toolbar.hide()
        self._video._controls_bar.hide()
        self._ui_visible = False

    def eventFilter(self, obj, event):
        from PySide6.QtCore import QEvent
        from PySide6.QtWidgets import QLineEdit, QTextEdit, QSpinBox, QComboBox
        if event.type() == QEvent.Type.KeyPress:
            # Only intercept when slideshow is the active window
            if not self.isActiveWindow():
                return super().eventFilter(obj, event)
            # Don't intercept keys when typing in text inputs
            if isinstance(obj, (QLineEdit, QTextEdit, QSpinBox, QComboBox)):
                return super().eventFilter(obj, event)
            key = event.key()
            mods = event.modifiers()
            if key == Qt.Key.Key_P and mods & Qt.KeyboardModifier.ControlModifier:
                self.privacy_requested.emit()
                return True
            elif key == Qt.Key.Key_H and mods & Qt.KeyboardModifier.ControlModifier:
                if self._ui_visible:
                    self._hide_timer.stop()
                    self._hide_overlay()
                else:
                    self._show_overlay()
                return True
            elif key in (Qt.Key.Key_Escape, Qt.Key.Key_Q):
                # Don't dispatch CloseRequested here — closeEvent
                # dispatches it after saving geometry. The state
                # machine sees the close exactly once and the
                # geometry persistence (adapter-side concern) runs
                # before the EmitClosed effect fires.
                self.close()
                return True
            elif key in (Qt.Key.Key_Left, Qt.Key.Key_H):
                self._dispatch_and_apply(NavigateRequested(direction=-1))
                return True
            elif key in (Qt.Key.Key_Right, Qt.Key.Key_L):
                self._dispatch_and_apply(NavigateRequested(direction=1))
                return True
            elif key in (Qt.Key.Key_Up, Qt.Key.Key_K):
                self._dispatch_and_apply(NavigateRequested(direction=-self._grid_cols))
                return True
            elif key in (Qt.Key.Key_Down, Qt.Key.Key_J):
                self._dispatch_and_apply(NavigateRequested(direction=self._grid_cols))
                return True
            elif key in (Qt.Key.Key_B, Qt.Key.Key_F):
                self.bookmark_requested.emit()
                return True
            elif key == Qt.Key.Key_S:
                self.toggle_save_requested.emit()
                return True
            elif key == Qt.Key.Key_F11:
                self._dispatch_and_apply(FullscreenToggled())
                return True
            elif key == Qt.Key.Key_Space and self._stack.currentIndex() == 1:
                self._dispatch_and_apply(TogglePlayRequested())
                return True
            elif key == Qt.Key.Key_Period and self._stack.currentIndex() == 1:
                # +/- keys are seek-relative, NOT slider-pin seeks. The
                # state machine's SeekRequested models slider-driven
                # seeks (target_ms known up front); relative seeks go
                # straight to mpv. If we ever want the dispatch path to
                # own them, compute target_ms from current position and
                # route through SeekRequested.
                self._video._seek_relative(1800)
                return True
            elif key == Qt.Key.Key_Comma and self._stack.currentIndex() == 1:
                self._video._seek_relative(-1800)
                return True
        if event.type() == QEvent.Type.Wheel and self.isActiveWindow():
            # Horizontal tilt navigates between posts on either stack
            tilt = event.angleDelta().x()
            if tilt > 30:
                self._dispatch_and_apply(NavigateRequested(direction=-1))
                return True
            if tilt < -30:
                self._dispatch_and_apply(NavigateRequested(direction=1))
                return True
            # Vertical wheel adjusts volume on the video stack only
            if self._stack.currentIndex() == 1:
                self._vol_scroll_accum += event.angleDelta().y()
                steps = self._vol_scroll_accum // 120
                if steps:
                    self._vol_scroll_accum -= steps * 120
                    vol = max(0, min(100, self._video.volume + 5 * steps))
                    self._dispatch_and_apply(VolumeSet(value=vol))
                    self._video.volume = vol
                    self._show_overlay()
                    return True
        if event.type() == QEvent.Type.MouseMove and self.isActiveWindow():
            # Map cursor position to window coordinates
            cursor_pos = self.mapFromGlobal(event.globalPosition().toPoint() if hasattr(event, 'globalPosition') else event.globalPos())
            y = cursor_pos.y()
            h = self.height()
            zone = max(60, h // 10)  # ~10% of window height, floor 60px
            if y < zone:
                self._toolbar.show()
                self._hide_timer.start()
            elif y > h - zone and self._stack.currentIndex() == 1:
                self._video._controls_bar.show()
                self._hide_timer.start()
            self._ui_visible = self._toolbar.isVisible() or self._video._controls_bar.isVisible()
        return super().eventFilter(obj, event)

    def privacy_hide(self) -> None:
        """Cover the popout's content with a black overlay for privacy.

        The popout window itself is NOT hidden — Wayland's hide→show
        round-trip drops position because the compositor unmaps and
        remaps the window, and Hyprland may re-tile the remapped window
        depending on its rules. Instead we raise an in-place black
        QWidget overlay over the central widget. The window stays
        mapped, position is preserved automatically, video is paused.
        """
        if self._stack.currentIndex() == 1:
            self._video.pause()
        central = self.centralWidget()
        if central is not None:
            self._privacy_overlay.setGeometry(0, 0, central.width(), central.height())
        self._privacy_overlay.raise_()
        self._privacy_overlay.show()

    def privacy_show(self) -> None:
        """Lift the black overlay and resume video. Counterpart to privacy_hide."""
        self._privacy_overlay.hide()
        if self._stack.currentIndex() == 1:
            self._video.resume()

    def _enter_fullscreen(self) -> None:
        """Enter fullscreen — capture windowed geometry first so F11 back can restore it.

        Also capture the current windowed state into the persistent
        `_viewport` so the F11-exit restore lands at the user's actual
        pre-F11 position, not at a stale viewport from before they last
        dragged the window. The drift detection in `_derive_viewport_for_fit`
        only fires when `_last_dispatched_rect` is set AND a fit is being
        computed — neither path catches the "user dragged the popout
        with Super+drag and then immediately pressed F11" sequence,
        because Hyprland Super+drag doesn't fire Qt's moveEvent and no
        nav has happened to trigger a fit. Capturing fresh into
        `_viewport` here makes the restore correct regardless.
        """
        from PySide6.QtCore import QRect
        win = hyprland.get_window(self.windowTitle())
        if win and win.get("at") and win.get("size"):
            x, y = win["at"]
            w, h = win["size"]
            self._windowed_geometry = QRect(x, y, w, h)
            ax, ay = anchor_point(x, y, w, h, self._anchor)
            self._viewport = Viewport(
                center_x=ax, center_y=ay,
                long_side=float(max(w, h)),
                anchor=self._anchor,
            )
        else:
            self._windowed_geometry = self.frameGeometry()
            rect = self._windowed_geometry
            if rect.width() > 0 and rect.height() > 0:
                ax, ay = anchor_point(rect.x(), rect.y(), rect.width(), rect.height(), self._anchor)
                self._viewport = Viewport(
                    center_x=ax, center_y=ay,
                    long_side=float(max(rect.width(), rect.height())),
                    anchor=self._anchor,
                )
        self.showFullScreen()

    def _exit_fullscreen(self) -> None:
        """Leave fullscreen — let the persistent viewport drive the restore.

        With the Group B persistent viewport in place, F11 exit no longer
        needs to re-arm the `_first_fit_pending` one-shots. The viewport
        already holds the pre-fullscreen center + long_side from before
        the user pressed F11 — fullscreen entry doesn't write to it,
        and nothing during fullscreen does either (no `_fit_to_content`
        runs while `isFullScreen()` is True). So the next deferred fit
        after `showNormal()` reads the persistent viewport, computes the
        new windowed rect for the current content's aspect, and dispatches
        — landing at the pre-fullscreen CENTER with the new shape, which
        also fixes the legacy F11-walks-toward-saved-top-left bug 1f as a
        side effect of the Group B refactor.

        We still need to invalidate `_last_dispatched_rect` because the
        cached value is from the pre-fullscreen window, and after F11
        Hyprland may report a different position before the deferred fit
        catches up — we don't want the drift detector to think the user
        moved the window externally during fullscreen.
        """
        content_w, content_h = 0, 0
        if self._stack.currentIndex() == 1:
            mpv = self._video._mpv
            if mpv:
                try:
                    vp = mpv.video_params
                    if vp and vp.get('w') and vp.get('h'):
                        content_w, content_h = vp['w'], vp['h']
                except Exception:
                    # mpv is mid-shutdown or between files; leave
                    # content_w/h at 0 so the caller falls back to the
                    # saved viewport rather than a bogus fit rect.
                    pass
        else:
            pix = self._viewer._pixmap
            if pix and not pix.isNull():
                content_w, content_h = pix.width(), pix.height()
        FullscreenPreview._saved_fullscreen = False
        # Invalidate the cache so the next fit doesn't false-positive on
        # "user moved the window during fullscreen". The persistent
        # viewport stays as-is and will drive the restore.
        self._last_dispatched_rect = None
        self.showNormal()
        if content_w > 0 and content_h > 0:
            # Defer to next event-loop tick so Qt's showNormal() is processed
            # by Hyprland before our hyprctl batch fires. Without this defer
            # the two race and the window lands at top-left.
            QTimer.singleShot(0, lambda: self._fit_to_content(content_w, content_h))

    def resizeEvent(self, event) -> None:
        super().resizeEvent(event)
        # Position floating overlays
        central = self.centralWidget()
        if central is None:
            return
        w = central.width()
        h = central.height()
        tb_h = self._toolbar.sizeHint().height()
        self._toolbar.setGeometry(0, 0, w, tb_h)
        ctrl_h = self._video._controls_bar.sizeHint().height()
        self._video._controls_bar.setGeometry(0, h - ctrl_h, w, ctrl_h)
        # Privacy overlay covers the entire central widget when active.
        if self._privacy_overlay.isVisible():
            self._privacy_overlay.setGeometry(0, 0, w, h)
        # Capture corner-resize into the persistent viewport so the
        # long_side the user chose survives subsequent navigations.
        #
        # GATED TO NON-HYPRLAND. On Wayland (Hyprland included), Qt
        # cannot know the window's absolute screen position — xdg-toplevel
        # doesn't expose it to clients — so `self.geometry()` returns
        # `QRect(0, 0, w, h)` regardless of where the compositor actually
        # placed the window. If we let this branch run on Hyprland, every
        # configure event from a hyprctl dispatch (or from the user's
        # Super+drag, or from `showNormal()` exiting fullscreen) would
        # corrupt the viewport center to ~(w/2, h/2) — a small positive
        # number far from the screen center — and the next dispatch
        # would project that bogus center, edge-nudge it, and land at
        # the top-left. Bug observed during the Group B viewport rollout.
        #
        # The `_applying_dispatch` guard catches the synchronous
        # non-Hyprland setGeometry path (where moveEvent fires inside
        # the try/finally block). It does NOT catch the async Hyprland
        # path because Popen returns instantly and the configure-event
        # → moveEvent round-trip happens later. The Hyprland gate
        # below is the actual fix; the `_applying_dispatch` guard
        # remains for the non-Hyprland path.
        #
        # On Hyprland, external drags/resizes are picked up by the
        # cur-vs-last-dispatched comparison in `_derive_viewport_for_fit`,
        # which reads `hyprctl clients -j` (the only reliable absolute
        # position source on Wayland).
        import os
        if os.environ.get("HYPRLAND_INSTANCE_SIGNATURE"):
            if self._tiled_pending_content is not None:
                self._untile_refit_timer.start()
            return
        if self._applying_dispatch or self.isFullScreen():
            return
        rect = self.geometry()
        if rect.width() > 0 and rect.height() > 0:
            ax, ay = anchor_point(rect.x(), rect.y(), rect.width(), rect.height(), self._anchor)
            self._viewport = Viewport(
                center_x=ax, center_y=ay,
                long_side=float(max(rect.width(), rect.height())),
                anchor=self._anchor,
            )
            # Parallel state machine dispatch for the same event.
            self._dispatch_and_apply(WindowResized(rect=(
                rect.x(), rect.y(), rect.width(), rect.height(),
            )))

    def moveEvent(self, event) -> None:
        super().moveEvent(event)
        # Capture user drags into the persistent viewport on the
        # non-Hyprland Qt path.
        #
        # GATED TO NON-HYPRLAND for the same reason as resizeEvent —
        # `self.geometry()` is unreliable on Wayland. See the long
        # comment in resizeEvent above for the full diagnosis. On
        # Hyprland, drag detection happens via the cur-vs-last-dispatched
        # comparison in `_derive_viewport_for_fit` instead.
        import os
        if os.environ.get("HYPRLAND_INSTANCE_SIGNATURE"):
            return
        if self._applying_dispatch or self.isFullScreen():
            return
        if self._viewport is None:
            return
        rect = self.geometry()
        if rect.width() > 0 and rect.height() > 0:
            # Move-only update: keep the existing long_side, just
            # update the anchor point to where the window now sits.
            ax, ay = anchor_point(rect.x(), rect.y(), rect.width(), rect.height(), self._anchor)
            self._viewport = Viewport(
                center_x=ax, center_y=ay,
                long_side=self._viewport.long_side,
                anchor=self._anchor,
            )
            # Parallel state machine dispatch for the same event.
            self._dispatch_and_apply(WindowMoved(rect=(
                rect.x(), rect.y(), rect.width(), rect.height(),
            )))

    def showEvent(self, event) -> None:
        super().showEvent(event)
        # Pre-warm the mpv GL render context as soon as the popout is
        # mapped, so the first video click doesn't pay for GL context
        # creation (~100-200ms one-time cost). The widget needs to be
        # visible for `makeCurrent()` to succeed, which is what showEvent
        # gives us. ensure_gl_init is idempotent — re-shows after a
        # close/reopen are cheap no-ops.
        try:
            self._video._gl_widget.ensure_gl_init()
        except Exception:
            # If GL pre-warm fails (driver weirdness, headless test),
            # play_file's lazy ensure_gl_init still runs as a fallback.
            pass

    def closeEvent(self, event) -> None:
        from PySide6.QtWidgets import QApplication
        # Save window state for next open BEFORE the state machine
        # dispatch — main_window's _on_fullscreen_closed handler reads
        # FullscreenPreview._saved_geometry / _saved_fullscreen, and
        # the EmitClosed effect (applied below) emits self.closed,
        # which triggers _on_fullscreen_closed. Geometry persistence
        # has to land first or main_window reads stale values.
        #
        # Geometry is adapter-side concern, not state machine concern,
        # so the state machine doesn't see it.
        FullscreenPreview._saved_fullscreen = self.isFullScreen()
        FullscreenPreview._saved_tiled = False
        if not self.isFullScreen():
            # On Hyprland, Qt doesn't know the real position — ask the WM
            win = hyprland.get_window(self.windowTitle())
            if win and win.get("floating") is False:
                # Tiled: reopen will re-tile instead of restoring geometry.
                FullscreenPreview._saved_tiled = True
            if win and win.get("at") and win.get("size"):
                from PySide6.QtCore import QRect
                x, y = win["at"]
                w, h = win["size"]
                FullscreenPreview._saved_geometry = QRect(x, y, w, h)
            else:
                FullscreenPreview._saved_geometry = self.frameGeometry()
        app = QApplication.instance()
        if app is not None:
            app.removeEventFilter(self)
        # Snapshot video position BEFORE StopMedia destroys it.
        # _on_fullscreen_closed reads this via get_video_state() to
        # seek the embedded preview to the same position.
        self._close_position_ms = (
            self._video.get_position_ms()
            if self.is_video_active()
            else 0
        )
        # NOW dispatch + apply CloseRequested. Effects are
        # [StopMedia, EmitClosed]. StopMedia clears the media stack;
        # EmitClosed emits self.closed which triggers main_window's
        # _on_fullscreen_closed handler.
        self._dispatch_and_apply(CloseRequested())
        # Tear down the popout's mpv + GL render context explicitly.
        # FullscreenPreview has no WA_DeleteOnClose and Qt's C++ dtor
        # doesn't reliably call Python-side destroy() overrides once
        # popout_controller drops its reference, so without this the
        # popout's separate mpv instance + NVDEC surface pool leak
        # until the next full Python GC cycle.
        try:
            self._video._gl_widget.cleanup()
        except Exception:
            # Close path — a cleanup failure can't be recovered from
            # here. Swallowing beats letting Qt abort mid-teardown.
            pass
        super().closeEvent(event)