| If this principle is absent… | This failure mode appears |
|---|---|
| Abstraction, Modularity | Tight coupling; hard to change |
| Idempotency | Silent Data Corruption (F3 #9) |
| Reproducibility | Heisenbugs; untestable systems |
| Fault Tolerance | Cascading Failures (F3 #2) |
| Observability | Observability Blindness (F3 #11) |
| Fail Fast | Silent Data Corruption (F3 #9) |
| Security Boundaries | Security Breach (F3 #10) |
| Consistency | Data Consistency Failure (F3 #4) |
| Least Privilege | Security Breach (F3 #10) |
This table is the fast path between a production incident and its root cause. When you see a failure mode, look up which absent principle created it. That is where the fix lives.