Reject unintended edge-update downgrades under an explicit version policy
Replaying an older signed image silently reverts a device. Add a declared minimum-version policy with a separate recovery mode.
- Focused work estimate
- 2h 45m + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Versioning · Security
Estimated field mix
- Security60%
- Embedded and edge40%
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 information kiosks receive small generated image blobs through a local update adapter. Simulate slots and boot outcomes in software; do not flash hardware or execute image contents.
Setup prerequisites
- Generate inert byte images with manifests and development-only signing fixtures.
- Implement simulated boot success failure and power-cut points.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
- CUPDATE-101 · Parse edge-update manifests with explicit supported versions
- CUPDATE-102 · Verify edge-update image size and digest before staging
- CUPDATE-103 · Validate edge-update manifests using local trust fixtures
- CUPDATE-104 · Write edge-update images only into the inactive simulated slot
- CUPDATE-105 · Record edge-update activation intent before changing the boot selector
- CUPDATE-106 · Mark an edge-update candidate healthy only after simulated boot confirmation
- CUPDATE-107 · Roll back failed edge-update boots without retry loops
Acceptance criteria
- Normal mode rejects lower versions
- Equal-version replay is idempotent
- Recovery override is explicit and audited locally
Implementation constraints
- Version order must be defined, not string-compared casually.
Verification to include
- Accept newer fixture
- Replay older signed fixture
Deliverables
- Version policy and override cases
Rollout and recovery
Disable updates if version comparison is ambiguous.
Value of the work
For the engineer: Practice update state machines and recoverable activation.
For the team: Inspect whether an engineer can prevent partial rollout from stranding devices under declared conditions.
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.