diff --git a/browse/test/cookie-import-browser.test.ts b/browse/test/cookie-import-browser.test.ts
index 5e9a5b441..ccf8e88b1 100644
--- a/browse/test/cookie-import-browser.test.ts
+++ b/browse/test/cookie-import-browser.test.ts
@@ -31,8 +31,12 @@ const LINUX_V11_KEY = crypto.pbkdf2Sync(LINUX_V11_PASSWORD, 'saltysalt', 1, 16,
 const IV = Buffer.alloc(16, 0x20);
 const CHROMIUM_EPOCH_OFFSET = 11644473600000000n;
 
-// Fixture DB path
-const FIXTURE_DIR = path.join(import.meta.dir, 'fixtures');
+// Fixture DB path — a per-run temp dir, NEVER the tracked browse/test/fixtures/:
+// these DBs are built in beforeAll and deleted in afterAll, so writing them
+// into the source tree makes them flash as `??` in git status mid-run, which
+// races any concurrent shard's tree-isolation porcelain snapshot (observed:
+// gen-skill-docs-out-dir's before/after porcelain pin on Windows CI).
+const FIXTURE_DIR = fs.mkdtempSync(path.join(os.tmpdir(), 'browse-cookie-fixtures-'));
 const FIXTURE_DB = path.join(FIXTURE_DIR, 'test-cookies.db');
 const LINUX_FIXTURE_DB = path.join(FIXTURE_DIR, 'test-cookies-linux.db');
 
diff --git a/scripts/test-free-shards.ts b/scripts/test-free-shards.ts
index 1762bbee3..d0bd8989e 100755
--- a/scripts/test-free-shards.ts
+++ b/scripts/test-free-shards.ts
@@ -407,6 +407,8 @@ export const TREE_MUTATING: Record<string, string> = {
     'golden tests read .agents/.factory artifacts produced by gen-skill-docs.test.ts, and its beforeAll generates them when missing (#2532) — must not race the parallel readers or run before the mutators window',
   'test/catalog-trim.test.ts':
     'imports scripts/gen-skill-docs.ts, whose top-level body regenerates the full claude host at import time (71 files; idempotent on a fresh tree, but a stale tree gets rewritten mid-window) — same hazard class as #2532',
+  'test/gen-skill-docs-out-dir.test.ts':
+    'PORCELAIN READER — its before/after git-status pin needs a quiet tree (a concurrent shard\'s transient fixture write raced it on Windows CI), and its spawned render rewrites llms.txt/agents-digest in place (idempotent on a fresh tree)',
   // Ratchet readers (measure the tree; need it quiet):
   'test/parity-suite.test.ts': 'RATCHET READER — parity caps measure live SKILL.md/section bytes',
   'test/skill-size-budget.test.ts': 'RATCHET READER — per-skill and corpus size budgets measure the live tree',