diff --git a/tests/harness/run.test.ts b/tests/harness/run.test.ts
new file mode 100644
index 0000000..6d4cae7
--- /dev/null
+++ b/tests/harness/run.test.ts
@@ -0,0 +1,144 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { mkdtempSync, rmSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import path from 'node:path';
+
+// `runAgentTurn` is stubbed so nothing here reaches a provider, a network call
+// or the real agent loop. The subject under test is the hook object
+// `executeHarnessRun` hands down -- specifically `requestApproval`, which is the
+// governance invariant at src/harness/run.ts:240.
+const runAgentTurn = vi.hoisted(() => vi.fn());
+vi.mock('../../src/agent/session.js', async importOriginal => {
+  const actual = await importOriginal<typeof import('../../src/agent/session.js')>();
+  return { ...actual, runAgentTurn };
+});
+
+import { createDvalinContext } from '../../src/core/context.js';
+import { executeHarnessRun } from '../../src/harness/run.js';
+import { createDefaultToolRegistry } from '../../src/tools/registry.js';
+import type { RunTurnHooks, RunTurnResult } from '../../src/agent/session.js';
+
+const cleanups: Array<() => void> = [];
+
+function tempDir(): string {
+  const dir = mkdtempSync(path.join(tmpdir(), 'dvalin-harness-test-'));
+  cleanups.push(() => rmSync(dir, { recursive: true, force: true }));
+  return dir;
+}
+
+/** A turn result shaped enough for `executeHarnessRun` to finish normally. */
+function turnResult(): RunTurnResult {
+  return {
+    sessionId: 'dc_harness_test',
+    providerId: 'mock',
+    model: 'mock-model',
+    policyHash: 'policy_hash',
+    result: {
+      runId: 'run_harness_test',
+      iterationsUsed: 1,
+      usage: { inputTokens: 1, outputTokens: 1 },
+      output: 'done',
+      stopReason: 'done',
+      auditHead: 'audit_head',
+    },
+  } as unknown as RunTurnResult;
+}
+
+/** The hooks object `executeHarnessRun` passed down on the last call. */
+function capturedHooks(): RunTurnHooks {
+  expect(runAgentTurn).toHaveBeenCalled();
+  return runAgentTurn.mock.calls.at(-1)![1] as RunTurnHooks;
+}
+
+beforeEach(() => {
+  runAgentTurn.mockReset();
+  runAgentTurn.mockResolvedValue(turnResult());
+});
+
+afterEach(() => {
+  vi.restoreAllMocks();
+  while (cleanups.length) cleanups.pop()!();
+});
+
+describe('executeHarnessRun approval policy', () => {
+  it('completes a run that never reaches an approval-gated tool', async () => {
+    const execution = await executeHarnessRun({ content: 'summarise the readme', cwd: tempDir() });
+
+    expect(execution.exitCode).toBe(0);
+    expect(runAgentTurn).toHaveBeenCalledTimes(1);
+  });
+
+  it('denies approval, because a headless run has no human to ask', async () => {
+    await executeHarnessRun({ content: 'edit a file', cwd: tempDir() });
+
+    const approved = await capturedHooks().requestApproval!(
+      'apv_test',
+      'write_file',
+      { filePath: 'a.txt' },
+    );
+
+    // This is the bypass-proof assertion. Change src/harness/run.ts:240 to
+    // `async () => true` and only this line goes red -- which is the whole
+    // point, because the failure mode being guarded is silent auto-approval in
+    // exactly the configuration with no human watching.
+    expect(approved).toBe(false);
+  });
+
+  it('resolves the denial promptly rather than waiting for input', async () => {
+    await executeHarnessRun({ content: 'edit a file', cwd: tempDir() });
+    const requestApproval = capturedHooks().requestApproval!;
+
+    // A hook that awaited a console or socket that will never speak would hang
+    // the run instead of failing it. Racing against an already-resolved promise
+    // asserts it settles without the event loop having to advance a timer.
+    const settled = await Promise.race([
+      requestApproval('apv_test', 'write_file', {}).then(() => 'settled'),
+      Promise.resolve('pending'),
+    ].map(p => Promise.resolve(p)));
+
+    await expect(requestApproval('apv_test', 'write_file', {})).resolves.toBe(false);
+    expect(settled).toBeDefined();
+  });
+
+  it('records the denial in the audit chain, not only in the return value', async () => {
+    // "Denied but unrecorded" must not pass. The denial is only visible to an
+    // operator if the tool layer wrote it down, so this drives the real
+    // registry with the harness's own hook rather than asserting on the hook
+    // alone.
+    await executeHarnessRun({ content: 'edit a file', cwd: tempDir() });
+    const requestApproval = capturedHooks().requestApproval!;
+
+    const events: Array<{ type: string; [key: string]: unknown }> = [];
+    const context = createDvalinContext({
+      cwd: tempDir(),
+      approvalMode: 'auto-edit',
+      requestApproval,
+      audit: { append: (event: unknown) => events.push(event as never) } as never,
+    });
+
+    await expect(
+      createDefaultToolRegistry().run('write_file', { filePath: 'a.txt', content: 'x' }, context),
+    ).rejects.toThrow(/rejected/i);
+
+    const approval = events.find(e => e.type === 'approval');
+    expect(approval, `no approval event was audited: ${JSON.stringify(events)}`).toBeDefined();
+    expect(approval).toMatchObject({ type: 'approval', toolName: 'write_file', approved: false });
+  });
+
+  it('does not write the file it was denied permission to write', async () => {
+    // The end the invariant exists for: a denial that still mutated the
+    // workspace would be an audit entry describing something that happened.
+    await executeHarnessRun({ content: 'edit a file', cwd: tempDir() });
+    const requestApproval = capturedHooks().requestApproval!;
+
+    const cwd = tempDir();
+    const context = createDvalinContext({ cwd, approvalMode: 'auto-edit', requestApproval });
+
+    await expect(
+      createDefaultToolRegistry().run('write_file', { filePath: 'created.txt', content: 'x' }, context),
+    ).rejects.toThrow(/rejected/i);
+
+    const { existsSync } = await import('node:fs');
+    expect(existsSync(path.join(cwd, 'created.txt'))).toBe(false);
+  });
+});