test(shard-engine): give non-timeout corpus fixtures CI headroom; keep the POSIX golden off the Windows lane

Only the wall-timeout fixture keeps a 3s wall; the rest get 60s so a loaded
host cannot turn a pass into a timeout. Base and branch runners still agree
on every classification under the new walls. The Windows exclusion entry
moves the free runner's ratchet (c) residual cap to 2356 lines.

scripts/test-free-shards.ts

@@ -338,6 +338,10 @@ export const KNOWN_WINDOWS_INCOMPATIBLE: Array<{ file: string; reason: string }>
     file: 'test/cso-witness.test.ts',
     reason: 'tests the contained repair witness with POSIX private-directory and compiled-helper assumptions; comprehensive execution is unavailable on Windows',
   },
+  {
+    file: 'test/shard-engine-equivalence.test.ts',
+    reason: 'its classification golden was recorded from the POSIX runners (process-group wall kill); the win32 engine path is pinned by the mocked-platform case in shard-engine.test.ts',
+  },
   {
     file: 'test/cso-scanner-cli.test.ts',
     reason: 'drives the prebuilt POSIX CSO launcher with /usr/bin/git and a POSIX-only PATH; native Windows launcher behavior is covered by the dedicated cso-windows-launcher gate',

test/fixtures/module-size-ratchet.json

@@ -4,7 +4,7 @@
     { "file": "test/helpers/module-size.ts", "movedFrom": "(new: ratchet (c) counter)" }
   ],
   "residualFiles": [
-    { "file": "scripts/test-free-shards.ts", "maxLines": 2352, "reason": "free lane policy after the shard engine took spawn, sandbox, logs, seeds and flags" },
+    { "file": "scripts/test-free-shards.ts", "maxLines": 2356, "reason": "free lane policy after the shard engine took spawn, sandbox, logs, seeds and flags" },
     { "file": "scripts/test-paid-shards.ts", "maxLines": 1921, "reason": "paid lane policy after the shard engine took sandbox, logs, seeds, verdicts and flags" }
   ],
   "allowlist": []

test/fixtures/shard-equivalence/record.ts

@@ -17,7 +17,9 @@ export const FIXTURES = [
   'pass', 'fail', 'skip', 'wall-timeout', 'module-load-error', 'zero-executed', 'unhandled-between-tests',
 ] as const;
 export const REAL_SHARD = 'test/strict-output.test.ts';
-const WALL_MS = 3_000;
+// Only the wall-timeout fixture should ever reach its wall; the others get
+// generous headroom so a loaded CI host cannot turn a pass into a timeout.
+const wallFor = (name: string) => (name === 'wall-timeout' ? 3_000 : 60_000);
 
 const root = path.resolve(process.argv[2] ?? path.join(import.meta.dir, '../../..'));
 const fixtureDir = import.meta.dir;
@@ -28,11 +30,11 @@ const freeExit = (status: string) => (status === 'passed' ? 0 : status === 'time
 
 try {
   const runFree = (file: string, index: number) => free.runFreeShard([file], index + 1, FIXTURES.length, {
-    rootDir: root, quiet: true, log: () => {}, wallTimeoutMs: WALL_MS,
+    rootDir: root, quiet: true, log: () => {}, wallTimeoutMs: wallFor(FIXTURES[index]),
     logFilePath: path.join(scratch, `free-${index}.log`),
   });
   const runPaid = (file: string, index: number) => paid.runPaidShard([file], index + 1, FIXTURES.length, {
-    rootDir: root, timeoutMs: WALL_MS, jobs: 2, logDir: scratch, log: () => {},
+    rootDir: root, timeoutMs: wallFor(FIXTURES[index]), jobs: 2, logDir: scratch, log: () => {},
     env: { ...process.env, GSTACK_CLAUDE_CLI_VERSION: 'fixture', EVALS: '', EVALS_TIER: '', EVALS_ALL: '' },
   });
   const files = FIXTURES.map(name => path.join(fixtureDir, `${name}.fixture.ts`));