Map native errors without losing machine-readable causes
Every nonzero native status becomes 'compression failed', hiding whether the caller supplied bad input or the allocator exhausted its cap.
- Focused work estimate
- 2h 30m + prerequisites
- Priority in the scenario
- Medium
- Engineering practice
- Error contracts · Boundary validation
Estimated field mix
- Systems programming70%
- API design30%
Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence.
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Project context
A fictional desktop backup tool calls a small Rust compression library from Node.js. The binding leaks buffers on exceptions and treats ABI mismatches as corrupted input. Build against generated byte arrays and a local native library; no production archive format or user files are supplied.
Setup prerequisites
- FFI ownership
- Binary compatibility
- Error handling
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- Stable public codes distinguish input, capacity, version, cancellation, and internal faults
- Native diagnostic text is bounded and treated as untrusted
- Unknown statuses map to one safe internal category
Implementation constraints
- Do not include raw input bytes or native addresses in errors.
Verification to include
- Trigger and map each declared native status.
- Return an unknown status with oversized text and verify bounded safe mapping.
Deliverables
- Versioned error map and contract tests
Rollout and recovery
Callers must stop branching on old free-form messages before migration.
Value of the work
For the engineer: Practice language-boundary contracts, native resource safety and version negotiation.
For the team: Review a binding that fails safely and can be rolled back before native code enters additional application paths.
Evidence boundaries
Outcome Evidence: Tests, patches, and runbooks are requested deliverables. They become Outcome Evidence only through a qualified Mission and immutable Evidence IDs.
Ownership Evidence: Independent adaptation must be observed under a declared verification policy and cite immutable Evidence IDs. Completing a planning ticket establishes no Ownership Evidence.