Verify completed object content before marking it available
Provider completion succeeds but the assembled bytes differ from the expected digest. Introduce a verification state.
- Focused work estimate
- 3h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Streaming · Hashing
Estimated field mix
- Storage systems80%
- Backend20%
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
Fictional document archive Fern stores synthetic byte objects. Use a local S3-compatible adapter or deterministic in-memory provider; no cloud credentials are needed.
Setup prerequisites
- Generate small deterministic byte fixtures.
- Implement local multipart provider responses including timeout and missing parts.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
- COBJS-101 · Normalize object names without treating them as filesystem paths
- COBJS-102 · Bind multipart upload sessions to organization and object identity
- COBJS-103 · Reject multipart uploads exceeding declared size limits
- COBJS-104 · Retry the same multipart part without creating contradictory receipts
- COBJS-105 · Validate ordered multipart completion against acknowledged parts
Acceptance criteria
- Available requires digest agreement
- Mismatch quarantines the object
- Verification retries do not republish
Implementation constraints
- Use bounded streaming hashing, not full-memory buffering.
Verification to include
- Verify matching bytes
- Flip one completed byte
Deliverables
- Post-completion verifier and corruption cases
Rollout and recovery
Keep newly completed objects unavailable if verification fails.
Value of the work
For the engineer: Practice object lifecycle, retry semantics and integrity verification.
For the team: Inspect whether uploads avoid corruption, orphan cost and tenant crossover.
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.