v0.8.0 — the board replays what everyone else did, instead of arriving rearranged

TODO #13, #15 and #18 — Gitea#20 steps 2-4 pointed at a seated player's own screen.
Every accepted intent, and every automatic phase that does anything, becomes an
ordered presentation step. A bot's whole switching turn used to land in one push;
now it arrives as a run of steps, the district panel follows whoever is acting,
and a [N behind] … [Skip] row says how far the board is from the game.

Solitaire runs the same path — one collector inside submit(), which both session
kinds already funnel through — which is where its automatic phases finally get a
visible beat.

Dwell is assigned by kind: switching holds the screen, turn bookkeeping costs
nothing, and the clock turning over earns the beat. Tunable per viewer without a
rebuild, and off entirely at pace 0.

Also: switching was the one class of action logging unattributed, and now names
its train. Reasoning, measurements and the three things that turned out wrong are
in CHANGELOG.md.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01X6cF1iYvJ1kNmzYBzu4QX6

src/web/session.ts

@@ -16,7 +16,10 @@
  */
 
 import type { Intent } from '../engine/intents.ts';
-import type { Frame } from '../sim/view.ts';
+import type { Frame, PublicFrame } from '../sim/view.ts';
+import { publicSnapshot } from '../sim/view.ts';
+import { takeSteps } from '../sim/display-step.ts';
+import type { DisplayStep } from '../sim/display-step.ts';
 import type { PlayerIndex } from '../engine/state.ts';
 import { applyDelta } from '../sim/frame-delta.ts';
 import type { FrameDelta } from '../sim/frame-delta.ts';
@@ -105,6 +108,28 @@ export type Session = {
    * starts — which is exactly when "is everyone here?" is the question.
    */
   presence(): { seat: PlayerIndex; connected: boolean; seen: boolean }[];
+  /**
+   * ORDERED PRESENTATION STEPS — v0.8.0, TODO #13. What everyone else did, in order, so it can be
+   * WATCHED rather than discovered.
+   *
+   * On the interface rather than on `LocalSession`, which is the whole point: solitaire drains its
+   * own collector and a remote session reads the same steps off `Push.steps`, so the page animates
+   * one queue and cannot tell which it has. That is what makes TODO #18 (solitaire's phases flying
+   * past) and TODO #13 (multiplayer's invisible turns) the same code path.
+   *
+   * NOT `steps()` — `LocalSession.steps()` already exists and counts submitted intents for the Undo
+   * button. Different thing entirely, hence the longer name.
+   */
+  takeDisplaySteps(): DisplayStep[];
+  /**
+   * A public frame to start the queue from, once — draining, and non-null only when the queue must
+   * be RESET rather than advanced.
+   *
+   * Steps carry deltas against a chain, so a client with no baseline cannot merge the next one. That
+   * happens on a first connect, on a reconnect, and locally after an undo or a restore — all of
+   * which rebuild from scratch. A reset means "throw away what is queued and draw this".
+   */
+  takeDisplayReset(): PublicFrame | null;
   /**
    * Stop listening, for good.
    *
@@ -145,6 +170,12 @@ export type LocalSession = Session & {
  */
 export function createLocalSession(seed: number, options?: NewGameOptions): LocalSession {
   let game: Game = options ? newGame(seed, configWith(options)) : newGame(seed);
+  /**
+   * The baseline the step queue starts from. Set here, and again whenever the game is REPLACED —
+   * `undo` and `restore` rebuild by replaying history, which (by design) collects no steps, so the
+   * queue has to be told to start over rather than left holding a chain that no longer continues.
+   */
+  let pendingReset: PublicFrame | null = publicSnapshot(game.state);
   const listeners = new Set<() => void>();
   const changed = (): void => {
     for (const fn of [...listeners]) fn();
@@ -186,6 +217,14 @@ export function createLocalSession(seed: number, options?: NewGameOptions): Loca
     },
     justDrawn: () => game.justDrawn,
     presence: () => [],
+    // Solitaire's own steps, from the same collector `submit()` fills for every seat of a
+    // multiplayer game. No separate code path — see `sim/display-step.ts`.
+    takeDisplaySteps: () => takeSteps(game.display),
+    takeDisplayReset: () => {
+      const reset = pendingReset;
+      pendingReset = null;
+      return reset;
+    },
 
     seed: () => game.seed,
     save: () => toSave(game),
@@ -199,6 +238,8 @@ export function createLocalSession(seed: number, options?: NewGameOptions): Loca
       back.scheduled = null;
       back.justDrawn = null;
       back.announced = null;
+      // The rebuilt game has an empty collector and a chain that starts over, so the queue must too.
+      pendingReset = publicSnapshot(back.state);
       changed();
       return true;
     },
@@ -207,6 +248,7 @@ export function createLocalSession(seed: number, options?: NewGameOptions): Loca
       // Restoring replays the whole history and re-records every draw; none of it is news.
       game.justDrawn = null;
       game.announced = null;
+      pendingReset = publicSnapshot(game.state);
       changed();
     },
   };
@@ -220,6 +262,10 @@ type Push = {
   lines: { text: string; tone: string }[];
   /** One entry for a change; every other seat at once on the connect push. */
   presence?: { seat: PlayerIndex; connected: boolean; seen: boolean }[];
+  /** Ordered presentation steps — v0.8.0, identical in every seat's push because they are public. */
+  steps?: DisplayStep[];
+  /** The baseline for the step queue, sent on a connect only. */
+  publicReset?: PublicFrame;
   /**
    * THE FOUR TRANSIENT SIGNALS, added 2026-08-23.
    *
@@ -270,6 +316,8 @@ export function createRemoteSession(
   let menu: Menu | null = null;
   let lines: { text: string; tone: string }[] = [];
   const presence = new Map<PlayerIndex, { connected: boolean; seen: boolean }>();
+  let displaySteps: DisplayStep[] = [];
+  let displayReset: PublicFrame | null = null;
   let cues: string[] = [];
   let scheduled: number | null = null;
   let announcement: string | null = null;
@@ -324,6 +372,21 @@ export function createRemoteSession(
     if (push.announcement !== undefined && push.announcement !== null) announcement = push.announcement;
     // Persists until another draw replaces it, matching the local session's own `justDrawn`.
     if (push.justDrawn !== undefined) justDrawnCard = push.justDrawn;
+    /**
+     * A RESET DISCARDS WHAT WAS QUEUED, rather than arriving alongside it.
+     *
+     * `publicReset` comes on a connect, which is also a RECONNECT — and a reconnecting client's
+     * queue holds steps whose deltas chain off a baseline the server has since moved past. Merging
+     * them onto the new baseline would draw a board that never existed. The history panel is what
+     * carries what was missed; the animation does not replay it (§ v0.8.0).
+     */
+    if (push.publicReset) {
+      displayReset = push.publicReset;
+      displaySteps = [];
+    }
+    // Accumulated, like cues: two pushes can land between two renders and every step is one thing
+    // that happened.
+    if (push.steps) displaySteps = [...displaySteps, ...push.steps];
     changed();
   };
 
@@ -376,6 +439,12 @@ export function createRemoteSession(
     },
     justDrawn: () => justDrawnCard,
     presence: () => [...presence].map(([seat, p]) => ({ seat, connected: p.connected, seen: p.seen })),
+    takeDisplaySteps: () => displaySteps.splice(0, displaySteps.length),
+    takeDisplayReset: () => {
+      const reset = displayReset;
+      displayReset = null;
+      return reset;
+    },
     close() {
       // `reportedGone` first: closing the stream fires `onerror`, and this is a deliberate exit, not
       // a game that vanished — `onGone` must not be called and land the page in "that game is no