# Anti-Patterns

> A catalog of violations. Each entry names the principle it breaches. Use this to recognize and reject patterns on sight.

## How to Use

When you see a pattern listed here, it is a defect. Cite the principle it violates and require a fix. These are not "to be reviewed later"; they are rejected on sight.

## Core Anti-Patterns (C1–C8)

| Anti-Pattern | Breaches | Why |
|--------------|----------|-----|
| Code that "mostly works" | C1 Correctness | Mostly correct is incorrect |
| `function doStuff()` | C2 Clarity | Name reveals nothing |
| A 500-line function | C3 Simplicity | Complexity is a liability |
| Config in a distant repo, read silently | C4 Locality | Coupling you cannot see |
| A migration with no `down` | C5 Reversibility | Irreversible bet |
| A component reading global state implicitly | C6 Composability | Hidden dependency |
| A service with no logs | C7 Observability | Cannot debug what you cannot see |
| Loading all records into memory | C8 Economy | Unbounded = OOM |

## Domain Anti-Patterns

### UI/UX
| Anti-Pattern | Breaches | Why |
|--------------|----------|-----|
| Image without `alt` | P2 Accessibility | Disqualifying |
| "Delete" with no confirmation | P5 Forgiveness | Irreversible surprise |
| `color: #3b82f6` in a component | P8 Consistency (via tokens) | Bypasses design system |
| "Submit" on a delete button | P3 Clarity | Wrong verb |
| Layout shift on image load | P7 Hierarchy / CLS | Visual instability |

### API
| Anti-Pattern | Breaches | Why |
|--------------|----------|-----|
| `/getUsers` (verb in URL) | P2 Clarity | Resources are nouns |
| 200 with an error body | P9 Error Transparency | Status code lies |
| 500 with a stack trace | P8 Security, P9 | Information leak |
| No `Idempotency-Key` on a POST | P6 Idempotency | Retry is unsafe |
| 10MB response by default | P7 Performance | Unbounded payload |

### Security
| Anti-Pattern | Breaches | Why |
|--------------|----------|-----|
| `eval()` of any string | P4, P5 | Code injection |
| Hardcoded API key in source | P9 Secret Hygiene | Committed secret |
| `catch (e) {}` (swallow) | P7, P8 | Silent failure, fail-open |
| `md5` for password hashing | P6 Crypto | Broken primitive |
| Open CORS `*` in production | P1, P10 | Zero trust violated |
| `chmod 777` | P2 Least Privilege | Maximum privilege |
| Logging the request body | P9 Secret Hygiene | Token leak |

### Data
| Anti-Pattern | Breaches | Why |
|--------------|----------|-----|
| `VARCHAR` for a UUID | P7 Type Fidelity | Wrong type |
| No FOREIGN KEY | P3, P9 | Unenforced relationship |
| `FLOAT` for money | P7, P1 | Floating point error |
| `is_deleted` without filtering | P8 Lifecycle | Soft-delete leak |
| `SELECT *` | P10 Performance | Unbounded columns |

### Testing
| Anti-Pattern | Breaches | Why |
|--------------|----------|-----|
| Test that cannot fail | P10 No Test Theater | Not a test |
| `Date.now()` in a fixture | P3 Determinism | Flaky |
| Shared fixture mutated across tests | P2 Independence | Order-dependent |
| 500 e2e tests, 50 unit | P4 Fast Feedback | Inverted pyramid |
| `name: "test"` fixture | P7 Realism | Hides bugs |

### Performance
| Anti-Pattern | Breaches | Why |
|--------------|----------|-----|
| N+1 query in a loop | P3 Complexity | O(N) queries |
| No timeout on HTTP call | P4, P8 (concurrency) | Hang forever |
| Cache with no invalidation | P5 Caching | Stale forever |
| Unbounded in-memory sort | P4 Resource Bounds | OOM |
| Optimization without measurement | P1 Measure First | Guesswork |

### Observability
| Anti-Pattern | Breaches | Why |
|--------------|----------|-----|
| `console.log("here")` | P1 Structured | Not queryable |
| `user_id` as a metric label | P4 Cardinality | Unbounded bill |
| Average latency only | P8 SLO | Hides the tail |
| No `trace_id` propagation | P2 Correlation | Cannot trace |
| Logs without `request_id` | P3 Context | No correlation |

### Errors
| Anti-Pattern | Breaches | Why |
|--------------|----------|-----|
| `catch (e) { return null }` | P2 Fail Loudly | Silent failure |
| `throw new Error("error")` | P3 Fail Specifically | Generic |
| `return null` for "not found" | P1 Errors are Data | Conflates absence with error |
| Retry without backoff | P5, P8 | Retry storm |
| `throw` in a recovery path | P6 | Fail fast in wrong place |

### Documentation
| Anti-Pattern | Breaches | Why |
|--------------|----------|-----|
| Doc with no examples | P3 Examples | Incomplete |
| Stale doc (wrong, not updated) | P4 Currency | Worse than no doc |
| Unlisted doc (not in MANIFEST) | (framework rule) | Not part of framework |
| No audience statement | P2 Audience | Who is this for? |

### Concurrency
| Anti-Pattern | Breaches | Why |
|--------------|----------|-----|
| Shared mutable state, no lock | P1 Immutability | Race condition |
| Unbounded queue | P9 Bounded Queues | OOM |
| `channel.send()` with no timeout | P8 Timeout | Hang |
| Mutex held across I/O | P3 Lock Scope | Lock too long |
| Spawned work with no cancellation | P7 Cancellation | Orphaned work |

### DevOps
| Anti-Pattern | Breaches | Why |
|--------------|----------|-----|
| Manual deploy script | P2 Automation | Not repeatable |
| No rollback path | P4 Rollback | Irreversible deploy |
| Big-bang deploy | P5 Progressive | All-or-nothing |
| Rebuild per environment | P7 Immutability | Different artifacts |
| Snowflake server | P1, P6 | Not reproducible |

## Cross-Cutting Anti-Patterns

| Anti-Pattern | Breaches | Why |
|--------------|----------|-----|
| "I'll add tests later" | C1 (no proof of correctness) | Later never comes |
| "It's just a prototype" | C5 (irreversible by default) | Prototypes go to prod |
| Copy-paste code | C6 (no composition) | Bug duplicated |
| God object | C3, C6 | One thing, many things |
| Leaky abstraction | C6, C2 | Hidden coupling |