test: add regression test for needs-remediation revalidation guard

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/resources/extensions/gsd/tests/needs-remediation-revalidation.test.ts

@@ -0,0 +1,48 @@
+/**
+ * Regression test for #3670 — needs-remediation verdict forces re-validation
+ *
+ * When validation returns needs-remediation, the state machine must route
+ * back to validating-milestone instead of completing-milestone. Without this,
+ * dispatch blocks completion for needs-remediation while state derives
+ * completing-milestone, creating a permanent deadlock.
+ *
+ * This structural test verifies the verdict === 'needs-remediation' guard
+ * exists at all three derivation paths in state.ts.
+ */
+
+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 source = readFileSync(join(__dirname, '..', 'state.ts'), 'utf-8');
+
+describe('needs-remediation revalidation guard (#3670)', () => {
+  test('verdict === needs-remediation guard exists in state.ts', () => {
+    const matches = source.match(/verdict\s*===\s*['"]needs-remediation['"]/g);
+    assert.ok(matches, 'verdict === "needs-remediation" check must exist in state.ts');
+    assert.ok(matches.length >= 2,
+      `Expected at least 2 needs-remediation guards (deriveStateFromDb + _deriveStateImpl), found ${matches.length}`);
+  });
+
+  test('needsRevalidation variable is derived from verdict', () => {
+    assert.match(source, /needsRevalidation.*=.*verdict\s*===\s*['"]needs-remediation['"]/,
+      'needsRevalidation should incorporate verdict === "needs-remediation"');
+  });
+
+  test('deriveStateFromDb path uses needs-remediation guard', () => {
+    assert.match(source, /!validationTerminal\s*\|\|\s*verdict\s*===\s*['"]needs-remediation['"]/,
+      'deriveStateFromDb should check !validationTerminal || verdict === "needs-remediation"');
+  });
+
+  test('extractVerdict is called on validation content', () => {
+    const extractCalls = source.match(/extractVerdict\(validationContent\)/g);
+    assert.ok(extractCalls, 'extractVerdict should be called on validation content');
+    assert.ok(extractCalls.length >= 2,
+      `Expected at least 2 extractVerdict calls, found ${extractCalls.length}`);
+  });
+});