diff --git a/src/resources/extensions/gsd/tests/prompt-step-ordering.test.ts b/src/resources/extensions/gsd/tests/prompt-step-ordering.test.ts
new file mode 100644
index 000000000..b456daf30
--- /dev/null
+++ b/src/resources/extensions/gsd/tests/prompt-step-ordering.test.ts
@@ -0,0 +1,82 @@
+/**
+ * Regression test for #3696 — prompt step ordering and runtime fixes
+ *
+ * 1. complete-milestone.md: gsd_requirement_update (step 9) before
+ *    gsd_complete_milestone (step 10)
+ * 2. complete-slice.md: uses gsd_requirement_update
+ * 3. register-extension.ts: _gsdEpipeGuard logs instead of re-throwing
+ * 4. register-hooks.ts: session_before_compact only checks isAutoActive
+ */
+
+import { describe, test } from 'node:test';
+import assert from 'node:assert/strict';
+import { readFileSync } from 'node:fs';
+import { fileURLToPath } from 'node:url';
+import { dirname, join } from 'node:path';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = dirname(__filename);
+
+const completeMilestoneMd = readFileSync(
+  join(__dirname, '..', 'prompts', 'complete-milestone.md'),
+  'utf-8',
+);
+const completeSliceMd = readFileSync(
+  join(__dirname, '..', 'prompts', 'complete-slice.md'),
+  'utf-8',
+);
+const registerExtSrc = readFileSync(
+  join(__dirname, '..', 'bootstrap', 'register-extension.ts'),
+  'utf-8',
+);
+const registerHooksSrc = readFileSync(
+  join(__dirname, '..', 'bootstrap', 'register-hooks.ts'),
+  'utf-8',
+);
+
+describe('prompt step ordering (#3696)', () => {
+  test('gsd_requirement_update appears before gsd_complete_milestone', () => {
+    const reqUpdateIdx = completeMilestoneMd.indexOf('gsd_requirement_update');
+    const completeMilestoneIdx = completeMilestoneMd.indexOf('gsd_complete_milestone');
+    assert.ok(reqUpdateIdx > -1, 'gsd_requirement_update should be in complete-milestone.md');
+    assert.ok(completeMilestoneIdx > -1, 'gsd_complete_milestone should be in complete-milestone.md');
+    assert.ok(
+      reqUpdateIdx < completeMilestoneIdx,
+      'gsd_requirement_update (step 9) must come before gsd_complete_milestone (step 10)',
+    );
+  });
+
+  test('complete-slice.md uses gsd_requirement_update', () => {
+    assert.match(completeSliceMd, /gsd_requirement_update/,
+      'complete-slice.md should reference gsd_requirement_update');
+  });
+});
+
+describe('register-extension _gsdEpipeGuard (#3696)', () => {
+  test('_gsdEpipeGuard exists and does not re-throw', () => {
+    assert.match(registerExtSrc, /_gsdEpipeGuard/,
+      '_gsdEpipeGuard should be defined in register-extension.ts');
+    // After the fix, the handler logs instead of throwing
+    assert.ok(
+      !registerExtSrc.includes('throw err'),
+      '_gsdEpipeGuard should NOT contain "throw err"',
+    );
+  });
+});
+
+describe('register-hooks session_before_compact (#3696)', () => {
+  test('session_before_compact only checks isAutoActive', () => {
+    // Extract the session_before_compact handler
+    const compactIdx = registerHooksSrc.indexOf('session_before_compact');
+    assert.ok(compactIdx > -1, 'session_before_compact hook should exist');
+    // The first check in the handler should be isAutoActive(), not isAutoPaused()
+    const afterCompact = registerHooksSrc.slice(compactIdx, compactIdx + 300);
+    assert.match(afterCompact, /isAutoActive\(\)/,
+      'session_before_compact should check isAutoActive()');
+    // Should NOT block compaction when paused
+    assert.ok(
+      !afterCompact.includes('isAutoPaused()'),
+      'session_before_compact should not check isAutoPaused',
+    );
+  });
+});