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

test/pacing.test.ts

@@ -0,0 +1,124 @@
+/**
+ * DWELL BY KIND — v0.8.0, `docs/plans/jitsi-common-board.md` § v0.8.0 § 5.
+ *
+ * The classification is exhaustive over `Intent['type']` at COMPILE time: `kindOf` declares a
+ * `StepKind` return and has no `default`, so a new intent breaks the build rather than landing
+ * silently in a fallback tier. These tests add the part the compiler cannot do — they read the
+ * intent union out of the source, so the guard survives someone later adding a `default:` that
+ * would swallow the very thing the exhaustiveness was protecting.
+ */
+
+import { describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import { readFileSync } from 'node:fs';
+import { dirname, join } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+import { DWELL, dwellFor, dwellForStep, kindOf, watchableCount } from '../src/sim/pacing.ts';
+import type { StepKind } from '../src/sim/pacing.ts';
+import type { Intent } from '../src/engine/intents.ts';
+
+const root = join(dirname(fileURLToPath(import.meta.url)), '..');
+
+/** Every `type: '…'` literal in the Intent union, read from the source rather than hand-listed. */
+function declaredIntents(): string[] {
+  const src = readFileSync(join(root, 'src/engine/intents.ts'), 'utf8');
+  return [...new Set([...src.matchAll(/type: '([a-zA-Z.]+)'/g)].map((m) => m[1]!))].sort();
+}
+
+const KINDS: StepKind[] = ['switching', 'action', 'phase', 'bookkeeping'];
+
+describe('pacing — dwell by kind', () => {
+  it('classifies every intent the engine declares', () => {
+    const declared = declaredIntents();
+    assert.ok(declared.length > 25, `only found ${declared.length} intents — the parse is wrong`);
+    for (const intent of declared) {
+      const kind = kindOf(intent as Intent['type']);
+      assert.ok(
+        KINDS.includes(kind),
+        `${intent} classified as "${kind}", which is not a StepKind — a default case has crept in`,
+      );
+    }
+  });
+
+  it('protects switching and collapses bookkeeping', () => {
+    // The two ends of the measured argument: a switching move is the thing worth watching, and
+    // `*.end` bookkeeping is over half of a real game's intents.
+    assert.equal(kindOf('switch.move'), 'switching');
+    assert.equal(kindOf('switch.dropCars'), 'switching');
+    assert.equal(kindOf('switch.sortConsist'), 'switching');
+    assert.equal(kindOf('draw.end'), 'bookkeeping');
+    assert.equal(kindOf('loadUnload.end'), 'bookkeeping');
+    assert.equal(kindOf('switch.end'), 'bookkeeping');
+    assert.equal(kindOf('localOps.choose'), 'bookkeeping');
+
+    assert.ok(DWELL.switching > DWELL.action, 'switching must outrank an ordinary action');
+    assert.equal(DWELL.bookkeeping, 0, 'bookkeeping must cost the player no time at all');
+  });
+
+  it('starts switching at a full second, per the 2026-09-09 decision', () => {
+    // Jesse: "start at 1s and tune down". Pinned so a later tune is a deliberate edit rather than
+    // a drift, and so the number in the plan and the number in the code cannot disagree.
+    assert.equal(DWELL.switching, 1000);
+    assert.equal(dwellFor('switch.move'), 1000);
+  });
+
+  it('scales with the viewer\'s pace, and 0 turns it off', () => {
+    assert.equal(dwellFor('switch.move', 1), 1000);
+    assert.equal(dwellFor('switch.move', 0.5), 500);
+    assert.equal(dwellFor('switch.move', 2), 2000);
+    // TODO #18's "a player who has seen it a hundred times will want it off" — no second mechanism.
+    for (const intent of declaredIntents()) {
+      assert.equal(dwellFor(intent as Intent['type'], 0), 0, `${intent} still dwells at pace 0`);
+    }
+    // A negative pace is a corrupt preference, not a request to run time backwards.
+    assert.equal(dwellFor('switch.move', -3), 0);
+  });
+
+  it('counts only the steps a player will actually watch', () => {
+    /**
+     * The counter's whole point. A backlog of 17 where 12 are bookkeeping must read "5", not "17"
+     * followed by an instant plummet to 5 — the countdown is meant to be steady enough to decide
+     * whether to press Skip.
+     */
+    const queue: Intent['type'][] = [
+      ...Array<Intent['type']>(12).fill('draw.end'),
+      ...Array<Intent['type']>(5).fill('switch.move'),
+    ];
+    assert.equal(queue.length, 17);
+    assert.equal(watchableCount(queue), 5);
+    assert.equal(watchableCount(queue, 0), 0, 'with animation off, nothing is behind');
+  });
+
+  it('a silent step beats only when the clock turns over — TODO #18', () => {
+    /**
+     * Both obvious rules were wrong, so both are pinned. "No narration, no dwell" flashed past
+     * phases that moved trains without saying so, killing the very thing #18 asks for. "Anything
+     * that changed the board" beat on every turn hand-off — `submit()` steps `advance()` about 4.6
+     * times per intent — which came to a quarter of an hour a game.
+     */
+    const silent = { cause: 'phase' as const, lines: [] as string[] };
+    assert.equal(dwellForStep({ ...silent, frame: { table: { actor: 2 } } }), 0, 'a turn hand-off shows nothing');
+    assert.equal(dwellForStep({ ...silent, frame: { table: {} } }), 0, 'a step that changed nothing shows nothing');
+    assert.equal(dwellForStep({ ...silent, frame: { table: { phase: 'mainline' } } }), DWELL.phase);
+    assert.equal(dwellForStep({ ...silent, frame: { table: { stage: 4 } } }), DWELL.phase);
+    // Narration always earns the dwell of whatever caused it, clock or no clock.
+    assert.equal(
+      dwellForStep({ cause: 'switch.move', lines: ['moved'], frame: { table: {} } }),
+      DWELL.switching,
+    );
+  });
+
+  it('a real switching turn is watchable in a few seconds, not tens of them', () => {
+    // Six moves is the engine's cap per crew ("N of 6 Moves left"), so this is the worst ordinary
+    // case for one crew and the arithmetic the design promised: ~6s to watch a whole exercise.
+    const turn: Intent['type'][] = [
+      'localOps.choose',
+      ...Array<Intent['type']>(6).fill('switch.move'),
+      'switch.end',
+    ];
+    const total = turn.reduce((ms, i) => ms + dwellFor(i), 0);
+    assert.equal(total, 6000);
+    assert.equal(watchableCount(turn), 6, 'the choose and the end are not things to watch');
+  });
+});