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| id | ticket | title | created | tags | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| LSN-0021 | pbs-learn-to-discussion-lessons-migration | PBS Diagnostics and Conformance Governance Legacy Import | 2026-03-27 |
|
Context
Legacy import from docs/compiler/pbs/learn/04. Diagnostics and Conformance Governance.md.
This lesson preserves the durable governance rules that survived the migration of broad policy ownership into general compiler specs.
Key Decisions
Diagnostics are stable by identity, not prose
What: Diagnostic correctness is keyed by stable identity fields rather than by localized or rendered wording.
Why: Conformance and regression evidence must survive wording changes and localization.
Trade-offs: Tooling must carry identity fields seriously, but the resulting diagnostic contract is auditable and stable.
Published claims require executable evidence
What: Conformance, compatibility, and support claims must be backed by maintained tests or artifact checks appropriate to the claim level.
Why: Published support without executable proof creates documentation debt and ambiguous promises.
Trade-offs: Governance becomes stricter, but support language stops drifting away from the real implementation.
Patterns and Algorithms
- Prefer general compiler specs as the live owner for cross-language governance.
- Keep PBS-local guidance only for PBS-specific deltas and lessons.
- Align claim scope, tests, and compatibility language together.
- Be explicit when a surface is rescope-only rather than partially supported.
Pitfalls
- Leaving superseded local policy docs around as if they still owned the contract.
- Publishing support claims without maintained evidence.
- Allowing compatibility matrices and tests to drift apart.
- Leaving rescope decisions implicit, especially for deferred execution surfaces.
Takeaways
- Diagnostics and conformance must stay executable and auditable.
- Once general specs take ownership, PBS-local records should become lesson material rather than live policy.
- Honest rescoping is better than ambiguous “deferred” support language.