system-boundaries-are-validating-and-evolution-tolerant
OUT derived (depth 3)
All system boundaries simultaneously enforce strict input validation (typed exceptions, referential integrity checks, hallucination filtering) and tolerate evolution gracefully (dual format parsers, forward-compatible metadata, schema-tolerant loading) — boundaries are both strict about current invariants and adaptive to future changes.
Summary
Every place where the system exchanges data with the outside world — APIs, file imports, database reads — applies two complementary strategies at once: it strictly rejects bad input right now (like throwing errors on duplicates or filtering out hallucinated references), while also gracefully handling older or newer data formats it wasn't originally built for (like falling back to alternative parsers or ignoring unrecognized fields). This means boundaries act as both gatekeepers and adapters, keeping current data clean without breaking when the system evolves.
Justifications
SL — Comprehensive validation (depth-2) and evolution tolerance (depth-1) are opposing concerns unified at system boundaries — strictness for correctness coexists with flexibility for evolution
Antecedents (all must be IN):
- input-validation-is-comprehensive-at-all-boundaries — Input validation is enforced at every system boundary through complementary mechanisms: typed exceptions (ValueError for duplicates, PermissionError for access violations) enforce API-level preconditions at the call boundary, while defense-in-depth reference validation (import normalization dropping unknown refs, nogood filtering skipping invalid nodes, hallucinated ID rejection) catches invalid node references at every data-acceptance boundary.
- system-tolerates-evolution-at-all-boundaries — The system handles format and schema evolution gracefully at every external boundary: derive output parsers support two format versions with automatic fallback, belief import silently skips unknown metadata fields, and storage tolerates missing tables from older database schemas via exception handling
Dependents
These beliefs depend on this one:
- deterministic-reasoning-within-evolution-tolerant-boundaries — The deterministic reversible reasoning engine — producing predictable terminating results through uniform evaluation — operates within system boundaries that gracefully handle format and schema evolution, ensuring deterministic correctness remains stable as external data formats change over time.
- format-resilient-boundaries-enforce-validated-trust — All system boundaries simultaneously tolerate format variation at every level — from LLM response parsing through schema migration to derive output versioning — while enforcing strict validated trust through typed exceptions, referential integrity checks, and hallucination filtering.
- system-boundary-enforcement-spans-validation-resilience-and-resources — All system boundaries simultaneously enforce three independent properties: strict input validation through typed exceptions and referential integrity checks that reject malformed or dangling references, forward-compatible resilience that tolerates format and schema evolution without requiring coordinated upgrades, and resource governance through accurate bidirectional token budgets with transitive subset-gated access control — boundaries serve as gates for correctness, adapters for evolution, and constraints on resource consumption.