# Principles Matrix > Maps every domain principle to the core principle(s) it derives > from. Used to verify that no domain rule is orphaned and to resolve > conflicts. **Core principles key:** C1=Correctness · C2=Clarity · C3=Simplicity · C4=Locality · C5=Reversibility · C6=Composability · C7=Observability · C8=Economy --- ## UI / UX | UI/UX Principle | Core | Why | |---------------------------|------|---------------------------------------| | P1 User Primacy | C2 | Clarity serves the user | | P2 Accessibility | C1 | Correctness for all abilities | | P3 Clarity | C2 | Direct derivation | | P4 Feedback | C7 | Observability for humans | | P5 Forgiveness | C5 | Reversibility of user actions | | P6 Performance | C1 | Correctness includes temporal correctness | | P7 Hierarchy | C2 | Clarity of priority | | P8 Consistency | C2 | Clarity through uniformity | | P9 Simplicity | C3 | Direct derivation | | P10 Reversibility | C5 | Direct derivation | ## API Design | API Principle | Core | Why | |---------------------------|------|---------------------------------------| | P1 Contract Fidelity | C1 | Correctness of the public contract | | P2 Clarity | C2 | Direct derivation | | P3 Predictability | C3 | Simplicity of mental model | | P4 Composability | C6 | Direct derivation | | P5 Versioning | C5 | Reversibility for consumers | | P6 Idempotency | C1 | Correctness under retry | | P7 Performance | C1 | Correctness includes latency | | P8 Security | C1 | Correctness includes safety | | P9 Error Transparency | C7 | Observability of failures | | P10 Stability | C5 | Reversibility of changes | ## Security | Security Principle | Core | Why | |---------------------------|------|---------------------------------------| | P1 Zero Trust | C1 | Correctness requires no false trust | | P2 Least Privilege | C3, C8 | Simplicity of access; economy of trust | | P3 Defense in Depth | C1 | Correctness under partial failure | | P4 Input Validation | C1 | Correctness of inputs | | P5 Output Safety | C1 | Correctness of outputs | | P6 Crypto Correctness | C1 | Crypto failures = correctness failures | | P7 Auditability | C7 | Observability of security events | | P8 Fail Securely | C1 | Correctness of failure modes | | P9 Secret Hygiene | C6, C7 | Composability of secrets; observability | | P10 Surface Minimization | C3, C8 | Simplicity; economy of code | ## Data | Data Principle | Core | Why | |---------------------------|------|---------------------------------------| | P1 Truth | C1 | Schema must match domain | | P2 Normalization | C1, C3 | Correctness without duplication; simplicity | | P3 Invariants in Schema | C1 | Correctness enforced | | P4 Migration Safety | C5 | Reversibility of changes | | P5 Indexing with Intent | C7 | Observability of query patterns | | P6 Naming Consistency | C2 | Direct derivation | | P7 Type Fidelity | C1, C2 | Correctness; clarity | | P8 Lifecycle Awareness | C1 | Correctness includes lifecycle | | P9 Referential Integrity | C1 | Correctness of relationships | | P10 Performance Awareness | C1 | Correctness includes cost | ## Testing | Testing Principle | Core | Why | |---------------------------|------|---------------------------------------| | P1 Tests as Specification | C2 | Tests document intent | | P2 Independence | C4 | Locality of test execution | | P3 Determinism | C1 | Correctness is reproducible | | P4 Fast Feedback | C3, C8 | Simplicity; economy of time | | P5 Coverage of Behavior | C1 | Correctness of behavior | | P6 Failure Specificity | C7 | Observability of failures | | P7 Realism | C1 | Correctness in real conditions | | P8 Maintainability | C3, C8 | Simplicity; economy of maintenance | | P9 Edge Case Coverage | C1 | Correctness at boundaries | | P10 No Test Theater | C1, C8 | Correctness; economy of test code | ## Performance | Perf Principle | Core | Why | |---------------------------|------|---------------------------------------| | P1 Measure First | C7 | Observability precedes optimization | | P2 Critical Path Focus | C3 | Simplicity of scope | | P3 Complexity Awareness | C1 | Correctness includes cost | | P4 Resource Bounds | C1, C8 | Correctness; economy of resources | | P5 Caching with Intent | C3, C6 | Simplicity; composability | | P6 Lazy by Default | C8 | Economy of computation | | P7 Async When Independent | C3 | Simplicity of flow | | P8 Budget Discipline | C8 | Economy of resources | | P9 Perceived Performance | C1 | Correctness from user's view | | P10 Regression Prevention | C7 | Observability of regressions | ## Observability | Obs Principle | Core | Why | |---------------------------|------|---------------------------------------| | P1 Structured by Default | C2, C7 | Clarity; observability | | P2 Correlation | C7 | Direct derivation | | P3 Sufficient Context | C7, C2 | Observability; clarity | | P4 Cardinality Discipline | C8 | Economy of storage/cost | | P5 Sampling with Intent | C8 | Economy of observability budget | | P6 No Secrets in Obs | C1, C6 | Correctness; composability | | P7 Actionable Alerts | C7, C8 | Observability; economy of attention | | P8 SLI/SLO Awareness | C1 | Correctness defined | | P9 Cost Awareness | C8 | Direct derivation | | P10 Debuggability | C2, C7 | Clarity; observability | ## Errors | Error Principle | Core | Why | |---------------------------|------|---------------------------------------| | P1 Errors are Data | C2, C7 | Clarity; observability | | P2 Fail Loudly | C7 | Direct derivation | | P3 Fail Specifically | C2, C7 | Clarity; observability | | P4 Preserve Context | C7 | Direct derivation | | P5 Recoverable When Possible | C1, C5 | Correctness; reversibility | | P6 Unrecoverable Means Stop | C1 | Correctness of failure mode | | P7 Errors are Boundaries | C6 | Composability | | P8 User-Facing Errors are UX | C2 | Clarity for users | | P9 Errors are Logged | C7 | Direct derivation | | P10 Errors Don't Lie | C1, C2 | Correctness; clarity | ## Documentation | Doc Principle | Core | Why | |---------------------------|------|---------------------------------------| | P1 Documentation is Code | C3, C8 | Simplicity; economy of process | | P2 Audience Awareness | C2 | Direct derivation | | P3 Examples are Mandatory | C2 | Direct derivation | | P4 Currency | C1 | Correctness of docs | | P5 Discoverability | C2 | Direct derivation | | P6 Conciseness | C3, C2 | Simplicity; clarity | | P7 Structure | C2 | Direct derivation | | P8 Why Over What | C2 | Direct derivation | | P9 Living Documents | C1, C5 | Correctness; reversibility | | P10 Public by Default | C6 | Composability | ## Concurrency | Concurrency Principle | Core | Why | |---------------------------|------|---------------------------------------| | P1 Immutability by Default | C1, C3 | Correctness; simplicity | | P2 Single Responsibility | C3, C6 | Simplicity; composability | | P3 Boundaries are Locks | C4, C6 | Locality; composability | | P4 Determinism Over Speed | C1 | Correctness precedes performance | | P5 Lock Minimization | C3 | Simplicity | | P6 No Silent Races | C7 | Observability of races | | P7 Cancellation Support | C5 | Reversibility of work | | P8 Timeout Discipline | C1 | Correctness of blocking | | P9 Bounded Queues | C1, C8 | Correctness; economy of memory | | P10 Test for Races | C1 | Correctness verification | ## DevOps | DevOps Principle | Core | Why | |---------------------------|------|---------------------------------------| | P1 Reproducibility | C1 | Correctness of environments | | P2 Automation | C3, C8 | Simplicity; economy of effort | | P3 Observability | C7 | Direct derivation | | P4 Rollback First | C5 | Direct derivation | | P5 Progressive Delivery | C5, C1 | Reversibility; correctness gradually | | P6 Configuration as Code | C1, C3 | Correctness; simplicity | | P7 Immutability | C1 | Correctness of deploys | | P8 Security at Every Layer | C1 | Correctness includes security | | P9 Documentation in Pipeline | C2 | Clarity of operations | | P10 Failure as Expected | C1, C7 | Correctness; observability |