v0.8.4 — the multiplayer transport: server and browser

The second release from the audit. Every fault here was invisible in solitaire, and four of
the five server faults were in the one file no test had ever stood up; `http.ts` now has an
end-to-end suite on a real port. CHANGELOG has the reasoning.

SERVER. Leaving a lobby freed the chair and kept the token, so a leaver could stream and
move for whoever took the seat next — revoked now, in memory and on disk. The browser
numbered intents from 1 per page load while the server remembered the seat's last number,
so the first move after a reload was swallowed as a resend — the connect push carries the
count and the client continues from it. Nothing serialised moves within a game and every
write shared one `.tmp` name, so two moves at once tore `game.json` (measured: 6 of 200),
and the boot's bare `JSON.parse` then took every game down — per-path write queues, a
per-game move queue, and a boot that skips one bad file. An error after the SSE head was
sent crashed the process. Bodies were unbounded before any secret check.

BROWSER. A double-click did the thing twice: one submit in flight at a time. A failed
submit is `false`, not an unhandled rejection. The documentation renderer flattened nested
bullets into a literal "- " mid-sentence on the published home-deck page. The make-up panel
promised cars the engine refuses; it asks `acceptsCar` now.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FrCWubm9GAftYCm2hWdKwK

test/server/persistence.test.ts

@@ -6,7 +6,8 @@ import { join } from 'node:path';
 
 import type { GameConfig } from '../../src/engine/state.ts';
 import type { SavedGame } from '../../src/server/session.ts';
-import { appendTiming, loadGame, writeGame } from '../../src/server/persistence.ts';
+import { appendTiming, loadGame, readIndex, upsertIndexEntry, writeGame } from '../../src/server/persistence.ts';
+import { writeFile } from 'node:fs/promises';
 
 const config: GameConfig = {
   mode: 'competitive',
@@ -101,4 +102,57 @@ describe('game persistence (Phase 3)', () => {
       const timings = JSON.parse(text) as unknown[];
       assert.equal(timings.length, 2);
     }));
+
+  // -- v0.8.4: concurrent writers ---------------------------------------------------------------
+
+  it('two hundred concurrent writes to one save leave it valid and never throw (v0.8.4)', () =>
+    withTempDir(async (dir) => {
+      /**
+       * One fixed `.tmp` per path, and no queue: measured at 200 rounds of two concurrent writes,
+       * every round lost one to `rename` ENOENT and six left the file as invalid JSON. Boot then
+       * died on it. Unique temp names and a per-path queue are the fix; this is the measurement.
+       */
+      const writes: Promise<void>[] = [];
+      for (let i = 0; i < 200; i++) {
+        const grown: SavedGame = { ...saved, history: Array.from({ length: i + 1 }, () => ({ type: 'draw.end' })) };
+        writes.push(writeGame(dir, grown, '1.2.3'));
+      }
+      await Promise.all(writes);
+      const result = await loadGame(dir);
+      assert.equal(result.found, true, 'the save is unreadable after concurrent writes');
+      if (result.found) assert.equal(result.saved.history.length, 200, 'the last write did not win');
+      await assert.rejects(() => readFile(join(dir, 'game.json.tmp')));
+    }));
+
+  it('two concurrent index upserts both land (v0.8.4)', () =>
+    withTempDir(async (dir) => {
+      await Promise.all([
+        upsertIndexEntry(dir, { gameId: 'a', gameCode: 'AAA-1', status: 'active' }),
+        upsertIndexEntry(dir, { gameId: 'b', gameCode: 'BBB-2', status: 'lobby' }),
+      ]);
+      const rows = await readIndex(dir);
+      assert.deepEqual(rows.map((r) => r.gameId).sort(), ['a', 'b'], 'a concurrent upsert lost a row');
+    }));
+
+  it('two concurrent timing appends both land (v0.8.4)', () =>
+    withTempDir(async (dir) => {
+      await Promise.all([
+        appendTiming(dir, { player: 0, phase: 'localOps', day: 1, stage: 1, startedAt: 1, endedAt: 2 }),
+        appendTiming(dir, { player: 1, phase: 'localOps', day: 1, stage: 1, startedAt: 2, endedAt: 3 }),
+      ]);
+      const timings = JSON.parse(await readFile(join(dir, 'turn-timings.json'), 'utf8')) as unknown[];
+      assert.equal(timings.length, 2);
+    }));
+
+  it('reports a save that is not JSON instead of throwing (v0.8.4)', () =>
+    withTempDir(async (dir) => {
+      await writeFile(join(dir, 'game.json'), '{"seed": 42, "hist');
+      const result = await loadGame(dir);
+      assert.equal(result.found, false);
+      if (!result.found) assert.ok(result.corrupt, 'a torn file was reported as merely missing');
+      await writeFile(join(dir, 'game.json'), '{"seed": 42}');
+      const shape = await loadGame(dir);
+      assert.equal(shape.found, false);
+      if (!shape.found) assert.match(shape.corrupt ?? '', /history/);
+    }));
 });