diff --git a/.gitignore b/.gitignore
index cdc6e12..7c8db67 100644
--- a/.gitignore
+++ b/.gitignore
@@ -21,6 +21,7 @@ mobile-*.png
 
 # Test scratch directories
 tests/__tmp_*/
+tests/tmp/
 
 # Local task tracking
 tasks/
diff --git a/tests/cas-locking.test.ts b/tests/cas-locking.test.ts
index 4630d9e..c46c7f1 100644
--- a/tests/cas-locking.test.ts
+++ b/tests/cas-locking.test.ts
@@ -1,10 +1,17 @@
 import { describe, it, expect, afterAll } from "bun:test";
-import { mkdirSync, writeFileSync, readFileSync, rmSync, existsSync } from "fs";
+import { rmdirSync, mkdirSync, writeFileSync, readFileSync, rmSync, existsSync } from "fs";
 import { join, dirname } from "path";
 import { computeHash } from "../src/core/read";
 import { acquireLock, acquireSortedLocks, LOCK_TIMEOUT_MS, lockPathFor, LockAcquireError, pruneStaleLocks } from "../src/core/locking";
 import { routeEdit } from "../src/core/router";
 
+// #110: each describe removes its own fixture, but the shared parent dirs were
+// left behind and dirtied `git status` after every run. Sweep them at file end.
+afterAll(() => {
+  try { rmSync("tests/tmp/cas-locking", { recursive: true, force: true }); } catch { /* ignore */ }
+  try { rmdirSync("tests/tmp"); } catch { /* non-empty or already gone */ }
+});
+
 function makeTestDir(name: string): { dir: string; cleanup: () => void } {
   const dir = join("tests/tmp/cas-locking", name);
   mkdirSync(dir, { recursive: true });
diff --git a/tests/intent.test.ts b/tests/intent.test.ts
index be43a76..14be0d0 100644
--- a/tests/intent.test.ts
+++ b/tests/intent.test.ts
@@ -1,4 +1,4 @@
-import { describe, test, expect, beforeEach, afterEach } from "bun:test";
+import { describe, test, expect, beforeEach, afterEach, afterAll } from "bun:test";
 import { parseIntent, findSymbolDefinition, findReferences, generatePlan, UnsupportedIntentError, resolveReferences } from "../src/core/intent";
 import { executePlan, executeIntent } from "../src/core/plan-executor";
 import type { VerifyResult } from "../src/core/verify";
@@ -8,6 +8,7 @@ import { simulateCrashAfterTempWrite } from "../src/core/paths";
 import { exitCodeFor } from "../src/core/exit-codes";
 
 const TMP_DIR = join(import.meta.dir, "__tmp_intent_tests__");
+const B15 = join(import.meta.dir, "__tmp_b15__");
 
 const FILE_A = join(TMP_DIR, "a.ts");
 const FILE_B = join(TMP_DIR, "b.ts");
@@ -71,6 +72,15 @@ function cleanup() {
   try { rmSync(TMP_DIR, { recursive: true, force: true }); } catch {}
 }
 
+// #110: several describe blocks call setup() without a matching afterEach, so
+// the fixture tree outlived the run and dirtied the working copy. A file-level
+// afterAll guarantees the scratch dirs are gone no matter which block created
+// them or whether a test threw partway through.
+afterAll(() => {
+  cleanup();
+  try { rmSync(B15, { recursive: true, force: true }); } catch {}
+});
+
 // ── parseIntent ──────────────────────────────────────────────────────
 
 describe("parseIntent", () => {
@@ -1069,8 +1079,6 @@ describe("executePlan verification / rollback correctness", () => {
 // references, decoys excluded, and unsupported languages reported as
 // `unresolved` rather than guessed.
 
-const B15 = join(import.meta.dir, "__tmp_b15__");
-
 function b15write(rel: string, content: string) {
   const abs = join(B15, rel);
   mkdirSync(join(abs, ".."), { recursive: true });
diff --git a/tests/locking-multiprocess.test.ts b/tests/locking-multiprocess.test.ts
index 802d59d..d1337c5 100644
--- a/tests/locking-multiprocess.test.ts
+++ b/tests/locking-multiprocess.test.ts
@@ -1,5 +1,5 @@
 import { describe, it, expect, beforeAll, afterAll } from "bun:test";
-import { mkdirSync, writeFileSync, rmSync, readFileSync, existsSync } from "fs";
+import { rmdirSync, mkdirSync, writeFileSync, rmSync, readFileSync, existsSync } from "fs";
 import { join, resolve, dirname } from "path";
 import { acquireLock, lockPathFor, pruneStaleLocks, LockAcquireError } from "../src/core/locking";
 
@@ -9,6 +9,13 @@ import { acquireLock, lockPathFor, pruneStaleLocks, LockAcquireError } from "../
 
 const LOCKING_MODULE = resolve("src/core/locking.ts");
 
+// #110: each describe removes its own fixture, but the shared parent dirs were
+// left behind and dirtied `git status` after every run. Sweep them at file end.
+afterAll(() => {
+  try { rmSync("tests/tmp/locking-mp", { recursive: true, force: true }); } catch { /* ignore */ }
+  try { rmdirSync("tests/tmp"); } catch { /* non-empty or already gone */ }
+});
+
 function makeTestDir(name: string): { dir: string; nested: string; cleanup: () => void } {
   const dir = resolve("tests/tmp/locking-mp", name);
   const nested = join(dir, "pkg", "deep");
diff --git a/tests/scratch-hygiene.test.ts b/tests/scratch-hygiene.test.ts
new file mode 100644
index 0000000..36ed721
--- /dev/null
+++ b/tests/scratch-hygiene.test.ts
@@ -0,0 +1,41 @@
+import { describe, it, expect } from "bun:test";
+import { existsSync, readFileSync } from "fs";
+import { join, resolve } from "path";
+
+// #110: `bun test` used to leave `tests/__tmp_intent_tests__/` and `tests/tmp/`
+// behind, so every run dirtied the working copy and the next run started from
+// stale fixtures. The guard is functional: run the owning test files in a child
+// process and assert the scratch trees are gone when it exits. .gitignore
+// covers the same roots as a backstop for a run that dies before afterAll fires.
+
+const REPO_ROOT = resolve(import.meta.dir, "..");
+
+async function runTestFile(file: string): Promise<number> {
+  const proc = Bun.spawn(["bun", "test", file], {
+    cwd: REPO_ROOT,
+    stdout: "pipe",
+    stderr: "pipe",
+    env: { ...process.env, HASHPILOT_TELEMETRY: "0" },
+  });
+  return await proc.exited;
+}
+
+describe("test scratch hygiene (#110)", () => {
+  it("intent tests leave no scratch tree under tests/", async () => {
+    await runTestFile("tests/intent.test.ts");
+    expect(existsSync(join(REPO_ROOT, "tests/__tmp_intent_tests__"))).toBe(false);
+    expect(existsSync(join(REPO_ROOT, "tests/__tmp_b15__"))).toBe(false);
+  }, 120_000);
+
+  it("locking tests leave no tests/tmp tree behind", async () => {
+    await runTestFile("tests/cas-locking.test.ts");
+    expect(existsSync(join(REPO_ROOT, "tests/tmp/cas-locking"))).toBe(false);
+    expect(existsSync(join(REPO_ROOT, "tests/tmp"))).toBe(false);
+  }, 120_000);
+
+  it("gitignore covers both scratch roots", () => {
+    const ignore = readFileSync(join(REPO_ROOT, ".gitignore"), "utf8");
+    expect(ignore).toContain("tests/__tmp_*/");
+    expect(ignore).toContain("tests/tmp/");
+  });
+});