Cache validated programs without confusing bytecode revisions
A cached validation result for version one is reused after an opcode gains a wider operand in version two.
- Focused work estimate
- 6h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Cache correctness · Versioning · Hashing
Estimated field mix
- Systems programming60%
- Compiler and language tooling40%
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 rules engine executes a tiny arithmetic bytecode over synthetic integers. Its interpreter trusts jump offsets and can run forever. Build a local Rust runtime; it has no filesystem, network, dynamic loading, host calls, or candidate-source execution.
Setup prerequisites
- Stacks
- Instruction decoding
- Control flow
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
- SRUNTIME-101 · Decode instructions without reading past the bytecode buffer
- SRUNTIME-102 · Validate stack depth across both sides of a branch
- SRUNTIME-103 · Reject jumps that land inside instruction operands
- SRUNTIME-104 · Report integer overflow instead of changing arithmetic by build mode
- SRUNTIME-105 · Stop infinite programs with a deterministic instruction budget
Acceptance criteria
- Cache identity binds exact bytes, bytecode version, validator version, and limits
- Validation failure is not cached across a newer validator
- Hash collision handling cannot return another program
Implementation constraints
- Cache entries contain immutable validated metadata and bounded program bytes only.
Verification to include
- Reuse one validated program under identical authority.
- Change each identity dimension and require a miss; inject a key collision and compare bytes.
Deliverables
- Versioned validation cache and collision tests
Rollout and recovery
Enable read-through caching after hit/miss telemetry reconciles with validation calls.
Value of the work
For the engineer: Practice runtime invariants, validation, resource accounting and compatibility.
For the team: Review a constrained execution component whose malformed programs fail deterministically without gaining host capabilities.
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.