diff --git a/bin/gstack-slug b/bin/gstack-slug
index e9b2aaf02..924454722 100755
--- a/bin/gstack-slug
+++ b/bin/gstack-slug
@@ -27,7 +27,11 @@
 # injection when consumed via source or eval.
 set -euo pipefail
 
-CACHE_DIR="$HOME/.gstack/slug-cache"
+# GSTACK_HOME-aware, matching lib/bin-context.ts's native port (#2561): the
+# bash writer and the TS reader must key the SAME cache, and a test running
+# with GSTACK_HOME=<temp> must write its cache junk there, not into the real
+# home (observed: 2,528 stale temp-cwd entries accumulated in ~/.gstack).
+CACHE_DIR="${GSTACK_HOME:-$HOME/.gstack}/slug-cache"
 PROJECT_DIR="$(pwd)"
 # Encode absolute path as cache key: /Users/j/foo → _Users_j_foo
 CACHE_KEY=$(printf '%s' "$PROJECT_DIR" | tr '/' '_')
@@ -37,8 +41,14 @@ SLUG=""
 
 # 0. Explicit env override — wins over everything. Escape hatch for vendored
 #    sub-repos and other genuine "subdir IS its own project" edge cases.
+SLUG_FROM_ENV=0
 if [[ -n "${GSTACK_PROJECT_SLUG:-}" ]]; then
   SLUG=$(printf '%s' "$GSTACK_PROJECT_SLUG" | tr -cd 'a-zA-Z0-9._-')
+  # Per-invocation escape hatch, never a durable identity: persisting it
+  # would rebind THIS cwd's slug for every later env-less run (observed: a
+  # test exporting GSTACK_PROJECT_SLUG from the repo root rebound the whole
+  # repo's session state to the test's slug).
+  SLUG_FROM_ENV=1
 fi
 
 # 1. Walk up from pwd, tracking the OUTERMOST ancestor with a canonical
@@ -160,7 +170,7 @@ SLUG="${SLUG:-$(basename "$PROJECT_DIR" | tr -cd 'a-zA-Z0-9._-')}"
 #     injection, but the invariant should not depend on that reasoning).
 SLUG=$(printf '%s' "$SLUG" | tr -cd 'a-zA-Z0-9._-')
 
-if [[ -n "$SLUG" ]]; then
+if [[ -n "$SLUG" && "$SLUG_FROM_ENV" -eq 0 ]]; then
   CURRENT_CACHE=""
   if [[ -f "$CACHE_FILE" ]]; then
     CURRENT_CACHE=$(cat "$CACHE_FILE" 2>/dev/null || true)
diff --git a/test/gstack-slug-sanitize.test.ts b/test/gstack-slug-sanitize.test.ts
index 7c5dc8f7d..9933ca01e 100644
--- a/test/gstack-slug-sanitize.test.ts
+++ b/test/gstack-slug-sanitize.test.ts
@@ -63,3 +63,40 @@ describe('gstack-slug cache-read sanitization', () => {
     }
   });
 });
+
+// The GSTACK_PROJECT_SLUG escape hatch is per-invocation, never durable: a
+// test exporting it from the repo root once rebound the ENTIRE repo's session
+// state (evals, decisions, timelines) to the test's slug via the cwd cache.
+// The cache is also GSTACK_HOME-aware now, matching lib/bin-context.ts's
+// native port — temp-home runs must not litter the real ~/.gstack (observed:
+// 2,528 stale temp-cwd entries).
+describe('slug cache hygiene', () => {
+  test('an env-override run never writes the cwd cache', () => {
+    const home = fs.mkdtempSync(path.join(os.tmpdir(), 'slug-env-'));
+    try {
+      const r = spawnSync(['bash', SLUG_BIN], {
+        cwd: os.tmpdir(),
+        env: { ...process.env, GSTACK_HOME: home, GSTACK_PROJECT_SLUG: 'override-slug' },
+      });
+      expect(r.stdout.toString()).toContain('SLUG=override-slug');
+      expect(fs.existsSync(path.join(home, 'slug-cache'))).toBe(false);
+    } finally {
+      fs.rmSync(home, { recursive: true, force: true });
+    }
+  });
+
+  test('an env-less run caches under GSTACK_HOME, not $HOME', () => {
+    const home = fs.mkdtempSync(path.join(os.tmpdir(), 'slug-home-'));
+    try {
+      const r = spawnSync(['bash', SLUG_BIN], {
+        cwd: os.tmpdir(),
+        env: { ...process.env, GSTACK_HOME: home },
+      });
+      expect(r.exitCode).toBe(0);
+      const entries = fs.readdirSync(path.join(home, 'slug-cache'));
+      expect(entries.length).toBe(1);
+    } finally {
+      fs.rmSync(home, { recursive: true, force: true });
+    }
+  });
+});
diff --git a/test/skill-e2e-cso.test.ts b/test/skill-e2e-cso.test.ts
index 64aa18bde..9bd0ed380 100644
--- a/test/skill-e2e-cso.test.ts
+++ b/test/skill-e2e-cso.test.ts
@@ -161,9 +161,14 @@ IMPORTANT:
 - Focus on changes in the current branch vs main.
 - The webhook.ts file was added on this branch — it should be analyzed.`,
       workingDirectory: csoDiffDir,
-      maxTurns: 25,
+      maxTurns: 40,
       allowedTools: ['Bash', 'Read', 'Write', 'Edit', 'Grep', 'Glob', 'Agent'],
-      timeout: 240_000,
+      // 360s/40 turns: the v1.67 wave grew the audit session legitimately —
+      // transcript-verified, the agent finds the webhook vuln, spawns the
+      // verification subagent, and writes the report, then gets killed at
+      // ~215s in its CLOSING telemetry under the old 240s/25-turn budget.
+      // The full-audit sibling already runs at 300s.
+      timeout: 360_000,
     });
 
     logCost('cso', result);
@@ -176,7 +181,7 @@ IMPORTANT:
     ).toBe(true);
 
     recordE2E(evalCollector, 'cso-diff-mode', 'e2e-cso', result);
-  }, 240_000);
+  }, 400_000);
 });
 
 describeIfSelected('CSO v2 — infra scope', ['cso-infra-scope'], () => {