diff --git a/tests/smoke/claude-companion.smoke.test.mjs b/tests/smoke/claude-companion.smoke.test.mjs
index 41b258eb..4c55ac0e 100644
--- a/tests/smoke/claude-companion.smoke.test.mjs
+++ b/tests/smoke/claude-companion.smoke.test.mjs
@@ -1759,11 +1759,11 @@ test("T7.4 / §21.3.2: prompt sidecar is deleted after worker consumes it", asyn
     // After the worker consumed the prompt, the sidecar must be gone.
     assert.equal(existsSync(path.join(jobDir, "prompt.txt")), false,
       "§21.3.1: prompt sidecar must be deleted after worker consumes it");
-    // Settle: meta.json flips to terminal BEFORE upsertJob writes state.json
-    // and BEFORE writeSidecar emits stdout.log/stderr.log. Without this
-    // wait, the recursive cleanup races the worker's tail writes and Linux
-    // CI flakes with `ENOTEMPTY` on rmdir of state/<subdir>/.
-    await new Promise((r) => setTimeout(r, 250));
+    // meta.json flips to terminal BEFORE upsertJob writes state.json and
+    // BEFORE writeSidecar emits stdout.log/stderr.log. Wait for the worker
+    // process to exit so cleanup() does not race those tail writes and flake
+    // with ENOTEMPTY on rmdir of state/<subdir>/.
+    await waitForProcessExit(ev.pid);
   } finally {
     cleanup(dataDir);
     rmSync(cwd, { recursive: true, force: true });
@@ -1965,6 +1965,10 @@ test("run --background: active job is visible as running and can be cancelled",
           "default status (no --all) must include cancelled jobs");
       }
     }
+    // Barrier: wait for the worker process to fully exit before cleanup so the
+    // recursive rmSync does not race its post-terminal tail writes (lease
+    // release, sidecar removal) and flake with ENOTEMPTY.
+    await waitForProcessExit(launched.pid, CLAUDE_SMOKE_POLL_TIMEOUT_MS);
   } finally {
     cleanup(dataDir);
     rmSync(cwd, { recursive: true, force: true });
@@ -2042,6 +2046,9 @@ test("cancel: SIGTERM-trapping target classifies as cancelled, not completed (is
     assert.ok(terminal, `job did not finalize after cancel; last status seen=${lastStatusSeen}`);
     assert.equal(terminal.status, "cancelled",
       `cancel-marker must force status=cancelled even when target trapped SIGTERM and exited 0; got ${JSON.stringify(terminal)}`);
+    // Barrier: ensure the worker process is gone before cleanup so the
+    // recursive rmSync does not race its post-terminal tail writes (ENOTEMPTY).
+    await waitForProcessExit(launched.pid, CLAUDE_SMOKE_POLL_TIMEOUT_MS);
   } finally {
     cleanup(dataDir);
     rmSync(cwd, { recursive: true, force: true });
@@ -2108,6 +2115,9 @@ process.kill = (pid, signal) => {
     assert.equal(cancelRes.status, 0, cancelRes.stderr);
     assert.equal(cancel.status, "already_dead");
     assert.equal(cancel.pid, running.pid_info.pid);
+    // Barrier: ensure the worker process is gone before cleanup so the
+    // recursive rmSync does not race its post-terminal tail writes (ENOTEMPTY).
+    await waitForProcessExit(launched.pid, CLAUDE_SMOKE_POLL_TIMEOUT_MS);
   } finally {
     cleanup(dataDir);
     rmSync(cwd, { recursive: true, force: true });
@@ -2296,7 +2306,9 @@ test("continue --job --background reuses the parent Claude project cwd", async (
     assert.equal(continued.status, "completed");
     assert.equal(continued.parent_job_id, parent.job_id);
     assert.equal(continued.runtime_diagnostics.child_cwd, parentRecord.runtime_diagnostics.child_cwd);
-    await new Promise((resolve) => setTimeout(resolve, 250));
+    // Wait for the background continue worker to exit before cleanup so the
+    // recursive rmSync does not race its tail writes and flake with ENOTEMPTY.
+    await waitForProcessExit(launched.pid);
   } finally {
     rmSync(dataDir, { recursive: true, force: true });
     rmSync(cwd, { recursive: true, force: true });
@@ -2552,6 +2564,7 @@ process.exit(0);
         (candidate) => candidate.status === "completed" || candidate.status === "failed",
         "background unapproved API continuation did not finalize",
       );
+      await waitForProcessExit(launched.pid);
     }
     assert.equal(unapproved.status, 2, unapproved.stderr || unapproved.stdout);
     const record = JSON.parse(unapproved.stdout);
@@ -4619,6 +4632,12 @@ process.exit(0);
     assert.equal(record.pid_info ?? null, null);
     assert.equal(record.external_review.source_content_transmission, "not_sent");
     assert.equal(existsSync(targetLaunchedPath), false);
+    // The cancelled record is durable before the worker finishes its tail
+    // writes (lease release, sidecar removal, lifecycle flush). Wait for the
+    // worker process to exit so cleanup() does not race a live writer and
+    // flake with ENOTEMPTY — same barrier the sibling preflight-rejection
+    // test above uses.
+    await waitForProcessExit(launched.pid);
   } finally {
     cleanup(dataDir);
     rmSync(cwd, { recursive: true, force: true });
@@ -5227,6 +5246,9 @@ process.exit(0);
     assert.equal(Object.hasOwn(record.review_metadata.audit_manifest, "approval_token"), false);
     assert.doesNotMatch(JSON.stringify(record), new RegExp(request.approval_token.value),
       "approved JobRecord must not persist the approval token");
+    // Wait for the worker process to exit before cleanup so the recursive
+    // rmSync does not race its post-terminal tail writes (ENOTEMPTY).
+    await waitForProcessExit(launched.pid);
   } finally {
     cleanup(dataDir);
     rmSync(cwd, { recursive: true, force: true });
@@ -5259,6 +5281,7 @@ test("background api_key source-bearing review without approval fails before pro
         (candidate) => candidate.status === "completed" || candidate.status === "failed",
         "background unapproved API run did not finalize",
       );
+      await waitForProcessExit(launched.pid);
     }
     assert.equal(run.status, 2, run.stderr || run.stdout);
     const record = JSON.parse(run.stdout);
diff --git a/tests/smoke/gemini-companion.smoke.test.mjs b/tests/smoke/gemini-companion.smoke.test.mjs
index 361afad1..621876a6 100644
--- a/tests/smoke/gemini-companion.smoke.test.mjs
+++ b/tests/smoke/gemini-companion.smoke.test.mjs
@@ -83,6 +83,25 @@ function rmTree(target) {
   }
 }
 
+// A background worker keeps writing into its data dir (lease release, sidecar
+// removal, lifecycle jsonl flush) AFTER its terminal JobRecord is durable.
+// Tests must wait for the worker PROCESS to exit before rmTree, or the
+// recursive removal races those tail writes and flakes with ENOTEMPTY.
+async function waitForProcessExit(pid, timeoutMs = 5000) {
+  if (!Number.isInteger(pid)) return;
+  const deadline = Date.now() + timeoutMs;
+  while (Date.now() < deadline) {
+    try {
+      process.kill(pid, 0);
+    } catch (error) {
+      if (error?.code === "ESRCH") return;
+      throw error;
+    }
+    await new Promise((resolve) => setTimeout(resolve, 100));
+  }
+  assert.fail(`worker process ${pid} did not exit`);
+}
+
 function assertPreflightSafetyFields(result) {
   assert.equal(result.target_spawned, false);
   assert.equal(result.selected_scope_sent_to_provider, false);
@@ -233,6 +252,8 @@ test("gemini custom-review background: launched event and terminal JobRecord", a
       disclosure: "Selected source content was sent to Gemini CLI for external review.",
     });
     assert.equal("prompt" in meta, false, "full prompt must not appear on JobRecord");
+    // Barrier: wait for the worker process to exit before cleanup (ENOTEMPTY race).
+    await waitForProcessExit(launched.pid);
   } finally {
     rmTree(dataDir);
     rmTree(cwd);
@@ -478,6 +499,8 @@ test("gemini rescue background: active job appears in default status", async ()
       if (!terminal) await new Promise((resolve) => setTimeout(resolve, 100));
     }
     assert.ok(terminal, "background job did not finish before cleanup");
+    // Barrier: wait for the worker process to exit before cleanup (ENOTEMPTY race).
+    await waitForProcessExit(launched.pid, GEMINI_SMOKE_POLL_TIMEOUT_MS);
   } finally {
     rmTree(dataDir);
     rmTree(cwd);
@@ -553,6 +576,8 @@ test("gemini cancel: signals a running background job (issue #22 sub-task 1)", a
         assert.equal(cancel.pid, running.pid_info.pid);
       }
     }
+    // Barrier: wait for the worker process to exit before cleanup (ENOTEMPTY race).
+    await waitForProcessExit(launched.pid, GEMINI_SMOKE_POLL_TIMEOUT_MS);
   } finally {
     rmTree(dataDir);
     rmTree(cwd);
@@ -921,6 +946,8 @@ test("gemini cancel: SIGTERM-trapping target classifies as cancelled, not comple
     assert.ok(terminal, "job did not finalize after cancel");
     assert.equal(terminal.status, "cancelled",
       `cancel-marker must force status=cancelled even when target trapped SIGTERM; got ${JSON.stringify(terminal)}`);
+    // Barrier: wait for the worker process to exit before cleanup (ENOTEMPTY race).
+    await waitForProcessExit(launched.pid, GEMINI_SMOKE_POLL_TIMEOUT_MS);
   } finally {
     rmTree(dataDir);
     rmTree(cwd);
@@ -986,6 +1013,8 @@ process.kill = (pid, signal) => {
     assert.equal(cancelRes.status, 0, cancelRes.stderr);
     assert.equal(cancel.status, "already_dead");
     assert.equal(cancel.pid, running.pid_info.pid);
+    // Barrier: wait for the worker process to exit before cleanup (ENOTEMPTY race).
+    await waitForProcessExit(launched.pid, GEMINI_SMOKE_POLL_TIMEOUT_MS);
   } finally {
     rmTree(dataDir);
     rmTree(cwd);
@@ -1350,6 +1379,8 @@ test("gemini continue background: launched event and resumed terminal JobRecord"
     assert.ok(fx, "worker never wrote stdout.log");
     assert.equal(fx.t7_resume_id, prior.gemini_session_id);
     assert.equal("prompt" in meta, false, "full prompt must not appear on JobRecord");
+    // Barrier: wait for the worker process to exit before cleanup (ENOTEMPTY race).
+    await waitForProcessExit(launched.pid);
   } finally {
     rmTree(first.dataDir);
     rmTree(cwd);
@@ -1401,6 +1432,8 @@ test("gemini _run-worker refuses terminal JobRecord without overwriting it", asy
     assert.equal(after.status, "completed");
     assert.match(after.result, /Mock Gemini response\./);
     assert.equal(after.gemini_session_id, GEMINI_SESSION_ID);
+    // Barrier: wait for the worker process to exit before cleanup (ENOTEMPTY race).
+    await waitForProcessExit(launched.pid);
   } finally {
     rmTree(dataDir);
     rmTree(cwd);
@@ -3496,6 +3529,8 @@ test("gemini approval-request token unlocks matching background api_key source-b
     assert.equal(terminal.review_metadata.audit_manifest.source_send_approval_required, true);
     assert.equal(terminal.review_metadata.audit_manifest.source_send_approval_state, "approved");
     assert.doesNotMatch(approval.stdout + launched.stdout + JSON.stringify(terminal), /secret-test-value/);
+    // Barrier: wait for the worker process to exit before cleanup (ENOTEMPTY race).
+    await waitForProcessExit(launchEvent.pid);
   } finally {
     rmTree(approval.dataDir);
     rmTree(cwd);