Prevent a mutable channel from changing an approved artifact
The beta channel is approved while pointing to one digest, then its mutable object is overwritten before clients resolve it.
- Focused work estimate
- 4h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Optimistic concurrency · Artifact channels
Estimated field mix
- DevOps70%
- Distributed systems30%
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 command-line product publishes local package archives. Builds contain timestamps, checksums are copied without provenance, and cleanup can delete the only rollback artifact. Use generated source trees, ephemeral development signing keys, and local object storage; no public registry or production key is supplied.
Setup prerequisites
- Content hashing
- Archive formats
- Release metadata
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
- DART-101 · Make archive bytes reproducible from the same source manifest
- DART-102 · Generate a dependency inventory from resolved inputs
- DART-103 · Bind provenance to source, builder, and exact artifact
- DART-104 · Keep signing keys outside the build workspace
- DART-105 · Promote only artifacts whose evidence set reconciles
Acceptance criteria
- Approval binds channel, digest, and revision
- Channel update uses compare-and-set against observed revision
- Clients can resolve historical channel revisions
Implementation constraints
- Channel is discovery metadata; the artifact remains content addressed and immutable.
Verification to include
- Advance beta from one approved digest to another.
- Race two channel updates and verify only one wins without overwriting history.
Deliverables
- Versioned channel pointer and concurrency test
Rollout and recovery
Enable one nondefault fixture channel before broader use.
Value of the work
For the engineer: Practice reproducible artifacts, provenance validation, signing-key isolation and retention safety.
For the team: Review a supply path that can trace, verify, retain, and revoke artifacts without relying on mutable names.
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.