chore: establish Strategy Lab source baseline (development, not release)

1 files changed, 38 insertions, 0 deletions

diff --git a/frontend/src/lib/draftGuard.test.ts b/frontend/src/lib/draftGuard.test.ts
new file mode 100644
index 0000000..a18de48
--- /dev/null
+++ b/frontend/src/lib/draftGuard.test.ts
@@ -0,0 +1,38 @@
+import { describe, expect, it } from 'vitest';
+import { unifiedDiffStats, ConflictResolver } from './draftGuard';
+
+describe('unifiedDiffStats', () => {
+  it('counts added and removed lines', () => {
+    const s = unifiedDiffStats('a\nb\n', 'a\nc\nd\n');
+    expect(s.added).toBe(2);
+    expect(s.removed).toBe(1);
+  });
+
+  it('is zero for identical inputs', () => {
+    const s = unifiedDiffStats('same', 'same');
+    expect(s.added).toBe(0);
+    expect(s.removed).toBe(0);
+  });
+});
+
+describe('ConflictResolver', () => {
+  const local = { generation: 1, code: 'x = 1\n' };
+
+  it('flags stale response: server generation ahead of local base', () => {
+    const r = new ConflictResolver(local);
+    const verdict = r.onServerState({ generation: 2, code: 'x = 2\n' }, local.generation);
+    expect(verdict.stale).toBe(true);
+  });
+
+  it('not stale when server generation equals local base generation', () => {
+    const r = new ConflictResolver(local);
+    const verdict = r.onServerState({ generation: 1, code: 'x = 1\n' }, local.generation);
+    expect(verdict.stale).toBe(false);
+  });
+
+  it('force-overwrite plan uses server generation to retry save', () => {
+    const r = new ConflictResolver(local);
+    const plan = r.retryPlan({ generation: 2, code: 'x = 2\n' } as const);
+    expect(plan).toEqual({ generation: 2, code: 'x = 1\n' });
+  });
+});