Draw the document trust boundary with authoritative state owners
The first sketch lets the API parse uploaded documents and write arbitrary worker status into the upload row.
- Focused work estimate
- 2h 30m + prerequisites
- Priority in the scenario
- Medium
- Engineering practice
- System boundaries · Threat modeling
Estimated field mix
- System design60%
- Security40%
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 procurement portal extracts metadata from uploaded documents. Product wants a responsive upload flow; security wants parser failures isolated from customer-facing processes.
Setup prerequisites
- Create synthetic upload metadata and a fake processing provider.
- Treat diagrams as proposals; implement only local contract probes.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- Identify storage, API, coordinator and isolated parser boundaries.
- Assign one owner to each lifecycle transition.
- Mark untrusted bytes and privileged credentials on data flows.
Implementation constraints
- Parsing belongs behind an explicit isolated provider; no candidate code runs in product processes.
Verification to include
- Trace a valid upload through every boundary.
- Trace a malformed document and show that parser failure cannot mutate API memory.
Deliverables
- Trust-boundary diagram and state-ownership table
Rollout and recovery
Review the boundary before implementation; reject paths that collapse isolation.
Value of the work
For the engineer: Practice boundary decisions backed by executable consistency and failure checks.
For the team: Review architecture tradeoffs with explicit assumptions before infrastructure commitment.
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.