feat(engine): in-engine replay playback core

Promotes the replay feature from disk-only to a real in-engine
playback path. A new ReplayPlaybackState resource models a three-
state machine (Inactive / Playing / Completed); start_replay_playback
resets the live game to the recorded deal via
GameState::new_with_mode(seed, draw_mode, mode) and a tick system
fires the canonical MoveRequestEvent / DrawRequestEvent for each
recorded move at REPLAY_MOVE_INTERVAL_SECS (0.45s).

The reset path bypasses NewGameRequestEvent because the existing
event always sources draw_mode from Settings — a Draw-1 replay
would silently coerce to Draw-3 (or vice versa) on a player whose
preference doesn't match the recording. Inserting GameStateResource
directly applies the recording's exact draw_mode and sidesteps the
abandon-current-game confirmation modal that would otherwise block
playback.

Recording suppression during playback is non-invasive: a sibling
system snapshots RecordingReplay's length on entry to playback and
truncates the buffer back to that mark every frame while is_playing
or is_completed. game_plugin's recording append paths are
untouched.

Completion lingers for REPLAY_COMPLETION_LINGER_SECS (5s) so the
overlay can show "Replay complete" before the auto-clear flips
state to Inactive.

Six new tests cover the state transitions, tick cadence, canonical
event firing, completion, stop-clears-state, and the
recording-suppression contract.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

solitaire_engine/src/lib.rs

@@ -24,6 +24,8 @@ pub mod onboarding_plugin;
 pub mod pause_plugin;
 pub mod profile_plugin;
 pub mod radial_menu;
+pub mod replay_overlay;
+pub mod replay_playback;
 pub mod settings_plugin;
 pub mod progress_plugin;
 pub mod resources;
@@ -112,6 +114,14 @@ pub use radial_menu::{
     legal_destinations_for_card, radial_anchor_for_index, radial_hovered_index, RadialIcon,
     RadialMenuPlugin, RightClickRadialState, Z_RADIAL_MENU,
 };
+pub use replay_overlay::{
+    ReplayOverlayBannerText, ReplayOverlayPlugin, ReplayOverlayProgressText, ReplayOverlayRoot,
+    ReplayStopButton, Z_REPLAY_OVERLAY,
+};
+pub use replay_playback::{
+    start_replay_playback, stop_replay_playback, ReplayPlaybackPlugin, ReplayPlaybackState,
+    REPLAY_COMPLETION_LINGER_SECS, REPLAY_MOVE_INTERVAL_SECS,
+};
 pub use settings_plugin::{
     PendingWindowGeometry, SettingsChangedEvent, SettingsPlugin, SettingsResource, SettingsScreen,
     SFX_STEP, WINDOW_GEOMETRY_DEBOUNCE_SECS,

solitaire_engine/src/replay_playback.rs

@@ -0,0 +1,682 @@
+//! In-engine replay playback core.
+//!
+//! When the player clicks "Watch replay" on the Stats overlay, the live
+//! game state is reset to the deal seeded from the replay's `seed` /
+//! `mode` / `draw_mode`, and the engine ticks through `replay.moves` at a
+//! steady cadence — firing the canonical [`MoveRequestEvent`] /
+//! [`DrawRequestEvent`] for each one. The existing animation pipeline
+//! plays back identically to a live game.
+//!
+//! ## Public surface
+//!
+//! - [`ReplayPlaybackState`] — single source of truth for whether
+//!   playback is live, how far through the move list we've ticked, and
+//!   how long until the next advance.
+//! - [`start_replay_playback`] — public entry point; the Stats
+//!   "Watch replay" button calls this. Resets the game to the recorded
+//!   deal and transitions the state machine to
+//!   [`ReplayPlaybackState::Playing`].
+//! - [`stop_replay_playback`] — interrupts playback at any time. Safe to
+//!   call when [`ReplayPlaybackState::Inactive`].
+//! - [`ReplayPlaybackPlugin`] — registers the resource and the tick /
+//!   linger systems.
+//!
+//! ## Coordination note
+//!
+//! This module is built in parallel with the Stats-side overlay. The
+//! resource shape, helper signatures, and plugin marker match the
+//! contract the overlay agent reads against — see also the docs on the
+//! enum variants.
+//!
+//! ## Recording is paused during playback
+//!
+//! Playback fires the same [`MoveRequestEvent`] / [`DrawRequestEvent`]
+//! the live engine handles. Without intervention, [`RecordingReplay`]
+//! would re-record those events and a replay would re-record itself
+//! indefinitely. To prevent that, [`record_replay_skip_during_playback`]
+//! snapshots the recording's length at the start of playback and
+//! truncates the buffer back to that length every frame. This keeps
+//! the recording contract opaque to `game_plugin` — no event-source
+//! flag is threaded through, no every-callsite gate is added.
+
+use bevy::prelude::*;
+use solitaire_data::{Replay, ReplayMove};
+
+use crate::events::{DrawRequestEvent, MoveRequestEvent, StateChangedEvent};
+use crate::game_plugin::{GameMutation, RecordingReplay};
+use crate::resources::GameStateResource;
+
+/// Per-move duration during playback. Tunable in Settings later;
+/// hardcoded for v1.
+pub const REPLAY_MOVE_INTERVAL_SECS: f32 = 0.45;
+
+/// How long the [`ReplayPlaybackState::Completed`] state lingers before
+/// the auto-clear system transitions it back to
+/// [`ReplayPlaybackState::Inactive`]. Gives the overlay UI time to
+/// display "Replay complete" before dismissing.
+pub const REPLAY_COMPLETION_LINGER_SECS: f32 = 5.0;
+
+/// Lifecycle state of an in-flight replay playback.
+///
+/// The default state is [`Inactive`](Self::Inactive) — no replay is
+/// running. The overlay (and any other consumer) reads this resource to
+/// decide whether the "Replay" banner should be visible and what
+/// progress to display.
+///
+/// Lifecycle:
+/// 1. Default state is [`Inactive`](Self::Inactive).
+/// 2. [`start_replay_playback`] transitions to
+///    [`Playing`](Self::Playing) and resets the live `GameState` to the
+///    replay's recorded deal.
+/// 3. The tick system [`tick_replay_playback`] advances `cursor` once
+///    per [`REPLAY_MOVE_INTERVAL_SECS`] and fires the canonical event
+///    for each [`ReplayMove`].
+/// 4. When `cursor == replay.moves.len()`, the state transitions to
+///    [`Completed`](Self::Completed). It lingers for
+///    [`REPLAY_COMPLETION_LINGER_SECS`] (driven by
+///    [`auto_clear_completed_replay`]) before returning to
+///    [`Inactive`](Self::Inactive).
+/// 5. [`stop_replay_playback`] interrupts at any time and forces the
+///    state back to [`Inactive`](Self::Inactive).
+#[derive(Resource, Debug, Default)]
+pub enum ReplayPlaybackState {
+    /// No replay is being played back. The overlay despawns itself when
+    /// the resource transitions back to this variant.
+    #[default]
+    Inactive,
+    /// A replay is currently being played back. The overlay reads
+    /// `replay.moves.len()` for the denominator of the progress
+    /// indicator and `cursor` for the numerator.
+    Playing {
+        /// The replay being played back. Owned so the state is the
+        /// only place playback metadata lives — no separate resource
+        /// needed.
+        replay: Replay,
+        /// Index of the next move to apply, in `[0, replay.moves.len()]`.
+        cursor: usize,
+        /// Seconds remaining until the next move is dispatched.
+        secs_to_next: f32,
+    },
+    /// The replay finished playing back. The overlay swaps the banner
+    /// label to "Replay complete" until [`auto_clear_completed_replay`]
+    /// transitions back to [`Inactive`](Self::Inactive) a few seconds
+    /// later.
+    Completed,
+}
+
+impl ReplayPlaybackState {
+    /// Returns `true` when a replay is currently being played back.
+    pub fn is_playing(&self) -> bool {
+        matches!(self, Self::Playing { .. })
+    }
+
+    /// Returns `true` when the replay has finished but the resource has
+    /// not yet been auto-cleared back to [`Self::Inactive`].
+    pub fn is_completed(&self) -> bool {
+        matches!(self, Self::Completed)
+    }
+
+    /// Returns `(cursor, total)` when a replay is in progress so the
+    /// overlay can render `"Move N of M"`. Returns `None` while
+    /// [`Inactive`](Self::Inactive) or [`Completed`](Self::Completed) —
+    /// the replay is consumed when transitioning out of `Playing`, so
+    /// the total is no longer available in `Completed`.
+    pub fn progress(&self) -> Option<(usize, usize)> {
+        match self {
+            Self::Playing { replay, cursor, .. } => Some((*cursor, replay.moves.len())),
+            Self::Inactive | Self::Completed => None,
+        }
+    }
+}
+
+/// Public entry point — call from the Stats "Watch replay" button
+/// handler.
+///
+/// Resets the live [`GameStateResource`] to a fresh deal seeded from
+/// `replay.seed` / `replay.draw_mode` / `replay.mode` (via
+/// [`Commands::insert_resource`]), then transitions the state machine
+/// to [`ReplayPlaybackState::Playing`] with `cursor: 0` and
+/// `secs_to_next: REPLAY_MOVE_INTERVAL_SECS`.
+///
+/// `commands` is used to overwrite [`GameStateResource`] in a deferred
+/// flush — equivalent to what `handle_new_game` does, minus the
+/// [`crate::events::NewGameRequestEvent`] round-trip and the
+/// abandon-current-game confirmation modal (which would block playback
+/// indefinitely). Using `Commands` rather than [`crate::events::NewGameRequestEvent`]
+/// also sidesteps the fact that `NewGameRequestEvent` has no
+/// `draw_mode_override` field — `handle_new_game` always reads
+/// `draw_mode` from `Settings`, which would silently coerce a Draw-1
+/// replay into a Draw-3 game (or vice versa) when the player's
+/// settings disagree with the recording.
+///
+/// Safe to call from any state — if a replay is already playing it is
+/// dropped and the new one starts immediately.
+pub fn start_replay_playback(
+    commands: &mut Commands,
+    state: &mut ResMut<ReplayPlaybackState>,
+    replay: Replay,
+) {
+    use solitaire_core::game_state::GameState;
+
+    let fresh = GameState::new_with_mode(replay.seed, replay.draw_mode.clone(), replay.mode);
+    commands.insert_resource(GameStateResource(fresh));
+
+    **state = ReplayPlaybackState::Playing {
+        replay,
+        cursor: 0,
+        secs_to_next: REPLAY_MOVE_INTERVAL_SECS,
+    };
+}
+
+/// Aborts an in-flight replay playback and resets
+/// [`ReplayPlaybackState`] back to [`ReplayPlaybackState::Inactive`].
+///
+/// Safe to call from any state — when already
+/// [`ReplayPlaybackState::Inactive`] it simply re-asserts inactivity.
+///
+/// The current [`GameStateResource`] is left as-is: the player sees the
+/// replay's most-recently-applied state until they start a fresh game
+/// manually. This avoids forcing an extra deal animation in their face
+/// the moment they cancel.
+///
+/// `commands` is currently unused but accepted to match the
+/// [`start_replay_playback`] signature — leaves room to hook in
+/// cleanup (e.g. despawning playback-only overlays) without a future
+/// API break.
+pub fn stop_replay_playback(
+    _commands: &mut Commands,
+    state: &mut ResMut<ReplayPlaybackState>,
+) {
+    **state = ReplayPlaybackState::Inactive;
+}
+
+/// Tick system. Runs every frame; only does work when
+/// [`ReplayPlaybackState::is_playing`].
+///
+/// Drains `secs_to_next` by `time.delta_secs()`. When the countdown
+/// expires, fires the canonical event for the move at `cursor`,
+/// increments `cursor`, and resets `secs_to_next`. When `cursor`
+/// reaches `replay.moves.len()`, transitions to
+/// [`ReplayPlaybackState::Completed`].
+///
+/// The advance loop is a `while`, not an `if`, so coarse time steps
+/// (e.g. test-driven 200 ms ticks against a 450 ms interval) still
+/// fire the right number of events — accumulated debt is paid off
+/// across as many advances as needed in the same frame. In normal
+/// gameplay frame deltas are well below `REPLAY_MOVE_INTERVAL_SECS`,
+/// so the loop runs at most once per frame.
+fn tick_replay_playback(
+    time: Res<Time>,
+    mut state: ResMut<ReplayPlaybackState>,
+    mut moves_writer: MessageWriter<MoveRequestEvent>,
+    mut draws_writer: MessageWriter<DrawRequestEvent>,
+) {
+    let dt = time.delta_secs();
+    let mut transition_to_completed = false;
+
+    if let ReplayPlaybackState::Playing {
+        replay,
+        cursor,
+        secs_to_next,
+    } = state.as_mut()
+    {
+        *secs_to_next -= dt;
+        while *secs_to_next <= 0.0 && *cursor < replay.moves.len() {
+            match &replay.moves[*cursor] {
+                ReplayMove::Move { from, to, count } => {
+                    moves_writer.write(MoveRequestEvent {
+                        from: from.clone(),
+                        to: to.clone(),
+                        count: *count,
+                    });
+                }
+                ReplayMove::StockClick => {
+                    draws_writer.write(DrawRequestEvent);
+                }
+            }
+            *cursor += 1;
+            *secs_to_next += REPLAY_MOVE_INTERVAL_SECS;
+        }
+
+        if *cursor >= replay.moves.len() {
+            transition_to_completed = true;
+        }
+    }
+
+    if transition_to_completed {
+        *state = ReplayPlaybackState::Completed;
+    }
+}
+
+/// Local timer for the [`ReplayPlaybackState::Completed`] linger.
+/// Resets to zero whenever the state transitions out of
+/// [`ReplayPlaybackState::Completed`].
+#[derive(Default)]
+struct CompletionLinger(f32);
+
+/// Auto-clear system. While [`ReplayPlaybackState::Completed`],
+/// accumulates time and transitions back to
+/// [`ReplayPlaybackState::Inactive`] once
+/// [`REPLAY_COMPLETION_LINGER_SECS`] has elapsed.
+fn auto_clear_completed_replay(
+    time: Res<Time>,
+    mut state: ResMut<ReplayPlaybackState>,
+    mut linger: Local<CompletionLinger>,
+) {
+    if state.is_completed() {
+        linger.0 += time.delta_secs();
+        if linger.0 >= REPLAY_COMPLETION_LINGER_SECS {
+            *state = ReplayPlaybackState::Inactive;
+            linger.0 = 0.0;
+        }
+    } else {
+        // Reset whenever we're not in Completed so the next completion
+        // measures from zero rather than accumulating across cycles.
+        linger.0 = 0.0;
+    }
+}
+
+/// Local cache of the recording buffer's length at the start of
+/// playback. Lets us roll back any growth during playback without
+/// touching `game_plugin`'s recording call sites.
+#[derive(Default)]
+struct RecordingSnapshot {
+    /// `Some(len)` while playback is active. The recording is
+    /// truncated back to this length every frame so playback-driven
+    /// events leak no entries into the recorded move list. `None`
+    /// when not playing — recording behaves normally.
+    snapshot_len: Option<usize>,
+}
+
+/// Recording-pause system. While [`ReplayPlaybackState::is_playing`],
+/// snapshots the recording's length on entry and truncates the
+/// recording back to that length every frame. This keeps the live
+/// [`RecordingReplay`] opaque to `game_plugin`'s `handle_move` /
+/// `handle_draw` — those still push unconditionally; we just wipe the
+/// playback-driven entries before any other system can read them.
+///
+/// Implemented this way because [`RecordingReplay`] is mutated inside
+/// the [`GameMutation`] system set (the schedule set that owns
+/// `handle_move` / `handle_draw`). We schedule this system
+/// `.after(GameMutation)` so the truncation runs each frame *after*
+/// the unconditional push, removing the same entry the playback tick
+/// caused.
+fn record_replay_skip_during_playback(
+    state: Res<ReplayPlaybackState>,
+    mut recording: ResMut<RecordingReplay>,
+    mut snap: Local<RecordingSnapshot>,
+) {
+    // Treat `Playing` and `Completed` identically for the purpose of
+    // recording suppression. The tick system's final advance fires
+    // its event in the same frame it transitions to `Completed`; the
+    // event is then consumed by `handle_move` / `handle_draw` either
+    // this frame (race-dependent on system order) or the next. By
+    // suppressing recording growth across both states, we close that
+    // window cleanly: the snapshot survives until the resource is
+    // back to `Inactive` (auto-cleared after
+    // `REPLAY_COMPLETION_LINGER_SECS`).
+    if state.is_playing() || state.is_completed() {
+        let baseline = match snap.snapshot_len {
+            Some(n) => n,
+            None => {
+                let n = recording.moves.len();
+                snap.snapshot_len = Some(n);
+                n
+            }
+        };
+        if recording.moves.len() > baseline {
+            recording.moves.truncate(baseline);
+        }
+    } else {
+        // Drop the snapshot when neither playing nor completed so
+        // the next playback cycle re-anchors to whatever the
+        // recording is at that point.
+        snap.snapshot_len = None;
+    }
+}
+
+/// On-completion side effect: fire a single [`StateChangedEvent`] when
+/// playback transitions from `Playing` to `Completed` so any UI that
+/// listens for state mutations refreshes one final time. Cheap and
+/// idempotent — `StateChangedEvent` is a one-shot signal.
+fn fire_state_changed_on_completion(
+    state: Res<ReplayPlaybackState>,
+    mut last_was_completed: Local<bool>,
+    mut writer: MessageWriter<StateChangedEvent>,
+) {
+    let now_completed = state.is_completed();
+    if now_completed && !*last_was_completed {
+        writer.write(StateChangedEvent);
+    }
+    *last_was_completed = now_completed;
+}
+
+/// Bevy plugin that initialises [`ReplayPlaybackState`] and drives
+/// playback ticks, completion linger, and the recording-pause guard.
+///
+/// Register this in the main app alongside [`crate::game_plugin::GamePlugin`].
+/// Tests can install it under [`MinimalPlugins`] to exercise the public
+/// API without spinning up the full client.
+pub struct ReplayPlaybackPlugin;
+
+impl Plugin for ReplayPlaybackPlugin {
+    fn build(&self, app: &mut App) {
+        app.init_resource::<ReplayPlaybackState>()
+            .add_systems(
+                Update,
+                (
+                    tick_replay_playback,
+                    auto_clear_completed_replay,
+                    fire_state_changed_on_completion,
+                )
+                    .chain(),
+            )
+            .add_systems(
+                Update,
+                record_replay_skip_during_playback.after(GameMutation),
+            );
+    }
+}
+
+// ---------------------------------------------------------------------------
+// Tests
+// ---------------------------------------------------------------------------
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::game_plugin::GamePlugin;
+    use bevy::time::TimeUpdateStrategy;
+    use chrono::NaiveDate;
+    use solitaire_core::game_state::{DrawMode, GameMode};
+    use solitaire_core::pile::PileType;
+    use std::time::Duration;
+
+    /// Builds a headless `App` with `MinimalPlugins`, `GamePlugin`, and
+    /// `ReplayPlaybackPlugin`. `GamePlugin` brings the canonical
+    /// `MoveRequestEvent` / `DrawRequestEvent` registrations along with
+    /// `RecordingReplay` so the recording-pause test can read it.
+    fn headless_app() -> App {
+        let mut app = App::new();
+        app.add_plugins(MinimalPlugins)
+            .add_plugins(GamePlugin::headless())
+            .add_plugins(ReplayPlaybackPlugin);
+        // Disable game-state persistence so tests don't touch the
+        // real ~/.local/share/solitaire_quest/game_state.json.
+        app.insert_resource(crate::game_plugin::GameStatePath(None));
+        app.insert_resource(crate::game_plugin::ReplayPath(None));
+        // Tick once so any startup systems flush before the first
+        // assertion.
+        app.update();
+        app
+    }
+
+    /// `Time<Virtual>` clamps each tick to `max_delta` (default 250 ms),
+    /// so we drive 200 ms steps and call `update` enough times to pass
+    /// the requested duration.
+    fn advance_by(app: &mut App, total_secs: f32) {
+        app.insert_resource(TimeUpdateStrategy::ManualDuration(
+            Duration::from_secs_f32(0.2),
+        ));
+        let ticks = (total_secs / 0.2).ceil() as usize + 1;
+        for _ in 0..ticks {
+            app.update();
+        }
+    }
+
+    /// A 3-move replay covering both `Move` and `StockClick` variants.
+    /// Seed 12345 is arbitrary — the test asserts on event counts and
+    /// move shapes, not on board positions.
+    fn sample_replay_three_moves() -> Replay {
+        Replay::new(
+            12345,
+            DrawMode::DrawOne,
+            GameMode::Classic,
+            60,
+            500,
+            NaiveDate::from_ymd_opt(2026, 5, 5).expect("valid date"),
+            vec![
+                ReplayMove::StockClick,
+                ReplayMove::Move {
+                    from: PileType::Waste,
+                    to: PileType::Tableau(3),
+                    count: 1,
+                },
+                ReplayMove::StockClick,
+            ],
+        )
+    }
+
+    /// Scoped helper to invoke `start_replay_playback` from within the
+    /// app's `World` (the public API takes `Commands`, which only
+    /// exists inside systems). We use a one-shot system to obtain the
+    /// `Commands`.
+    fn start_playback(app: &mut App, replay: Replay) {
+        #[derive(Resource)]
+        struct ReplayInbox(Option<Replay>);
+        app.insert_resource(ReplayInbox(Some(replay)));
+
+        fn run(
+            mut commands: Commands,
+            mut state: ResMut<ReplayPlaybackState>,
+            mut inbox: ResMut<ReplayInbox>,
+        ) {
+            if let Some(replay) = inbox.0.take() {
+                start_replay_playback(&mut commands, &mut state, replay);
+            }
+        }
+        let id = app.world_mut().register_system(run);
+        app.world_mut()
+            .run_system(id)
+            .expect("one-shot start_playback");
+    }
+
+    fn stop_playback(app: &mut App) {
+        fn run(mut commands: Commands, mut state: ResMut<ReplayPlaybackState>) {
+            stop_replay_playback(&mut commands, &mut state);
+        }
+        let id = app.world_mut().register_system(run);
+        app.world_mut()
+            .run_system(id)
+            .expect("one-shot stop_playback");
+    }
+
+    /// Fresh state must be `Inactive`. After `start_replay_playback`
+    /// the state must be `Playing { cursor: 0, .. }` carrying the
+    /// supplied replay.
+    #[test]
+    fn start_replay_playback_transitions_inactive_to_playing() {
+        let mut app = headless_app();
+        assert!(matches!(
+            *app.world().resource::<ReplayPlaybackState>(),
+            ReplayPlaybackState::Inactive
+        ));
+
+        let replay = sample_replay_three_moves();
+        start_playback(&mut app, replay.clone());
+        // Apply the deferred Commands flush.
+        app.update();
+
+        let state = app.world().resource::<ReplayPlaybackState>();
+        match state {
+            ReplayPlaybackState::Playing {
+                cursor,
+                replay: r,
+                ..
+            } => {
+                assert_eq!(*cursor, 0);
+                assert_eq!(r.seed, replay.seed);
+                assert_eq!(r.moves.len(), 3);
+            }
+            other => panic!("expected Playing, got {other:?}"),
+        }
+        assert_eq!(state.progress(), Some((0, 3)));
+    }
+
+    /// One full interval (plus a small margin to clear the boundary)
+    /// must advance the cursor by at least one.
+    #[test]
+    fn tick_advances_cursor_after_interval() {
+        let mut app = headless_app();
+        start_playback(&mut app, sample_replay_three_moves());
+        app.update();
+
+        // Drive virtual time forward by one interval.
+        advance_by(&mut app, REPLAY_MOVE_INTERVAL_SECS + 0.05);
+
+        let state = app.world().resource::<ReplayPlaybackState>();
+        match state {
+            ReplayPlaybackState::Playing { cursor, .. } => {
+                assert!(
+                    *cursor >= 1,
+                    "expected cursor advanced past one move, got {cursor}",
+                );
+            }
+            other => panic!("expected Playing, got {other:?}"),
+        }
+    }
+
+    /// Driving past `n * REPLAY_MOVE_INTERVAL_SECS` must produce
+    /// `n` events that match the recorded move kinds. We register a
+    /// pair of accumulator systems that drain `MoveRequestEvent` /
+    /// `DrawRequestEvent` into resources every frame — using a
+    /// detached cursor across many `app.update()` calls is unreliable
+    /// because Bevy's `Messages` double-buffer drops events older
+    /// than two frames.
+    #[test]
+    fn tick_fires_canonical_event_for_each_move() {
+        #[derive(Resource, Default)]
+        struct CapturedMoves(Vec<MoveRequestEvent>);
+        #[derive(Resource, Default)]
+        struct CapturedDraws(usize);
+
+        fn collect_moves(
+            mut events: MessageReader<MoveRequestEvent>,
+            mut sink: ResMut<CapturedMoves>,
+        ) {
+            for ev in events.read() {
+                sink.0.push(ev.clone());
+            }
+        }
+        fn collect_draws(
+            mut events: MessageReader<DrawRequestEvent>,
+            mut sink: ResMut<CapturedDraws>,
+        ) {
+            for _ in events.read() {
+                sink.0 += 1;
+            }
+        }
+
+        let mut app = headless_app();
+        app.init_resource::<CapturedMoves>()
+            .init_resource::<CapturedDraws>()
+            .add_systems(Update, (collect_moves, collect_draws));
+
+        start_playback(&mut app, sample_replay_three_moves());
+        app.update();
+
+        // Drive through 3 intervals. Add a small margin to ensure the
+        // last firing isn't sitting exactly on the boundary.
+        advance_by(&mut app, REPLAY_MOVE_INTERVAL_SECS * 3.0 + 0.1);
+
+        let captured_moves = app.world().resource::<CapturedMoves>();
+        let captured_draws = app.world().resource::<CapturedDraws>();
+
+        // Sample replay: StockClick, Move { Waste -> Tableau(3), 1 }, StockClick.
+        assert_eq!(
+            captured_draws.0, 2,
+            "expected 2 DrawRequestEvent (two StockClicks)",
+        );
+        assert_eq!(
+            captured_moves.0.len(),
+            1,
+            "expected 1 MoveRequestEvent (the single Move variant)",
+        );
+        let m = &captured_moves.0[0];
+        assert!(matches!(m.from, PileType::Waste));
+        assert!(matches!(m.to, PileType::Tableau(3)));
+        assert_eq!(m.count, 1);
+    }
+
+    /// Driving past one interval on a single-move replay must
+    /// transition to `Completed`.
+    #[test]
+    fn playback_completes_when_cursor_reaches_end() {
+        let mut app = headless_app();
+        let one_move = Replay::new(
+            42,
+            DrawMode::DrawOne,
+            GameMode::Classic,
+            10,
+            100,
+            NaiveDate::from_ymd_opt(2026, 5, 5).expect("valid date"),
+            vec![ReplayMove::StockClick],
+        );
+        start_playback(&mut app, one_move);
+        app.update();
+
+        advance_by(&mut app, REPLAY_MOVE_INTERVAL_SECS + 0.1);
+
+        let state = app.world().resource::<ReplayPlaybackState>();
+        assert!(
+            state.is_completed(),
+            "expected Completed after consuming the only move, got {state:?}",
+        );
+    }
+
+    /// `stop_replay_playback` must force the state back to `Inactive`
+    /// even mid-playback.
+    #[test]
+    fn stop_replay_playback_returns_to_inactive() {
+        let mut app = headless_app();
+        start_playback(&mut app, sample_replay_three_moves());
+        app.update();
+        // Tick once so the state is well and truly `Playing`.
+        advance_by(&mut app, 0.1);
+        assert!(app.world().resource::<ReplayPlaybackState>().is_playing());
+
+        stop_playback(&mut app);
+        app.update();
+
+        assert!(matches!(
+            *app.world().resource::<ReplayPlaybackState>(),
+            ReplayPlaybackState::Inactive
+        ));
+    }
+
+    /// Recording must remain frozen during playback. Pre-populate the
+    /// recording with one entry, start playback, and assert the
+    /// recording's move list is unchanged after several ticks.
+    #[test]
+    fn recording_paused_during_playback() {
+        let mut app = headless_app();
+        // Pre-populate the recording with one entry that should
+        // survive playback unchanged. Mirrors the situation where the
+        // player partway through a game opens stats and clicks Watch
+        // Replay — their in-flight recording must not get clobbered.
+        {
+            let mut rec = app.world_mut().resource_mut::<RecordingReplay>();
+            rec.moves.push(ReplayMove::StockClick);
+        }
+        start_playback(&mut app, sample_replay_three_moves());
+        app.update();
+
+        let baseline_len = app.world().resource::<RecordingReplay>().moves.len();
+        assert_eq!(
+            baseline_len, 1,
+            "preconditions: recording starts with one entry",
+        );
+
+        // Drive playback through every move in the replay. Each move
+        // would normally append to `RecordingReplay`; the pause
+        // system must clamp the recording back to `baseline_len` on
+        // every frame.
+        advance_by(&mut app, REPLAY_MOVE_INTERVAL_SECS * 4.0 + 0.1);
+
+        let after_len = app.world().resource::<RecordingReplay>().moves.len();
+        assert_eq!(
+            after_len, baseline_len,
+            "recording must not grow while playback is active",
+        );
+    }
+}