evalbuff: add patterns/implementation-validation.md (fde408c)

Author: jahooma

AGENTS.md

@@ -48,3 +48,4 @@ Make an efficient learning agent that can do anything.
 - [docs/patterns/template-literal-escaping.md](docs/patterns/template-literal-escaping.md)
 - [docs/patterns/task-scope-adherence.md](docs/patterns/task-scope-adherence.md)
 - [docs/patterns/task-type-identification.md](docs/patterns/task-type-identification.md)
+- [docs/patterns/implementation-validation.md](docs/patterns/implementation-validation.md)

docs/patterns/implementation-validation.md

@@ -0,0 +1,171 @@
+# Implementation Validation Pattern
+
+When you find existing code that appears to implement the requested functionality, always validate that it actually works before claiming the task is complete.
+
+## The Problem
+
+Agents often discover existing implementations and immediately conclude the task is done without testing functionality. This leads to:
+- Claiming features work when they don't
+- Missing broken configurations that look correct in code
+- Failing to communicate actual task status clearly
+- Users left uncertain whether their request was fulfilled
+
+## The Validation Process
+
+### 1. Find the Implementation
+
+When you discover code that seems to match the requirements:
+
+```bash
+# Found redirect in next.config.mjs
+{
+  source: '/b/:hash',
+  destination: 'https://go.trybeluga.ai/:hash',
+  permanent: false,
+}
+```
+
+### 2. Test the Actual Functionality
+
+Don't assume code works just because it exists. Test the user-facing behavior:
+
+```bash
+# For Next.js redirects - test the actual redirect
+curl -I http://localhost:3000/b/test123
+# Should return 307/308 with Location header
+
+# For API endpoints - test the endpoint
+curl http://localhost:3000/api/endpoint
+# Should return expected response
+
+# For UI features - verify the user flow works
+```
+
+### 3. Check Runtime vs Configuration
+
+Code existing ≠ code working. Verify the implementation is active:
+
+- **Next.js redirects**: Must be in active config AND server restarted
+- **API routes**: File must exist in correct location AND export right methods
+- **Features**: Code must be imported/called from the right places
+- **Environment**: Required env vars, database state, etc.
+
+### 4. Validate Against Exact Requirements
+
+Even working code might not match the specific requirements:
+
+- **URL patterns**: `/b/:hash` vs `/b/:id` vs `/buffer/:hash`
+- **Destinations**: `https://go.trybeluga.ai/:hash` vs other domains
+- **Behavior**: temporary vs permanent redirects, query handling
+
+## Response Patterns
+
+### ✅ When Implementation Works
+
+```
+I found the redirect configuration in next.config.mjs and verified it works:
+
+[show the existing code]
+
+Testing confirms functionality:
+$ curl -I http://localhost:3000/b/test123
+HTTP/1.1 307 Temporary Redirect
+Location: https://go.trybeluga.ai/test123
+
+The feature is already implemented and working correctly.
+```
+
+### ✅ When Implementation Exists But Broken
+
+```
+I found redirect configuration in next.config.mjs, but testing shows it's not working:
+
+[show the existing code]
+
+Testing reveals the issue:
+$ curl -I http://localhost:3000/b/test123
+HTTP/1.1 404 Not Found
+
+The server needs to be restarted for redirects to take effect.
+After restart, the redirect works correctly.
+```
+
+### ✅ When Implementation Is Missing
+
+```
+I need to add the redirect configuration to next.config.mjs:
+
+[show the changes being made]
+
+This will redirect /b/:hash to https://go.trybeluga.ai/:hash as requested.
+```
+
+## Testing Strategies by Feature Type
+
+### Web Redirects
+```bash
+curl -I http://localhost:PORT/path
+# Check status code (307/308) and Location header
+```
+
+### API Endpoints
+```bash
+curl http://localhost:PORT/api/endpoint
+# Check response status and body
+```
+
+### Database Features
+```bash
+# Check if tables/columns exist
+# Verify data can be inserted/queried
+# Test constraints and relationships
+```
+
+### UI Components
+```bash
+# Start dev server and manually test
+# Or run existing test suite
+bun test path/to/feature.test.ts
+```
+
+## Use Existing Tests When Available
+
+If tests exist for the feature:
+
+1. **Read the test file** to understand expected behavior
+2. **Run the tests** to verify current implementation
+3. **Report test results** as evidence of functionality
+
+Example:
+```typescript
+test('redirects to go.trybeluga.ai with the hash', async ({ request }) => {
+  const response = await request.get('/b/test123', { maxRedirects: 0 })
+  expect(response.status()).toBe(307)
+  expect(response.headers()['location']).toBe('https://go.trybeluga.ai/test123')
+})
+```
+
+If these tests exist and pass, the feature is confirmed working.
+
+## Anti-Patterns to Avoid
+
+❌ **Assuming functionality without testing**:
+```
+"The redirect is already implemented in next.config.mjs. No changes needed."
+// Without actually verifying it works
+```
+
+❌ **Confusing configuration with functionality**:
+```
+// Code exists in config file ≠ feature works at runtime
+```
+
+❌ **Silent completion without communication**:
+```
+// Making no changes and not explaining why
+// Leaving user unsure if their request was handled
+```
+
+## Key Principle
+
+**Code that looks right might not work right.** Always test the actual user-facing behavior before claiming a feature is complete. When in doubt, verify through testing rather than code inspection alone.