File upload: Storage and security design
Specifies object layout, metadata, isolation, validation, delivery, and threat controls for file upload. This reference fixes the adoption boundary, failure behavior, and observable evidence while leaving environment-specific limits configurable.
Package status: reference context ready for human review. The contract and test scenarios are complete, but no claim is made that an adopting implementation has passed them.
Decision
For File upload, adopt an ownership record separate from the opaque object key. Use one owned boundary, explicit state model, and versioned interfaces; keep policy decisions separate from adapters and side effects. This architecture block focuses specifically on storage and security design. This package is a reference contract: the adopting team must choose numeric limits, providers, jurisdictions, and operational owners from evidence in its own environment.
Scope
- The File upload actors, inputs, outputs, states, policy or schema versions, and externally visible outcomes required for the storage and security design focus of this architecture block.
- Primary and alternate interfaces, background work, caches, integrations, support paths, and evidence that can exercise the same boundary.
- Adoption-specific configuration, rollout, recovery, and verification responsibilities needed to apply the reference safely.
Outside this block
- Choosing a universal vendor, framework, jurisdiction, numeric threshold, retention period, or service-level objective for every adopter.
- Claiming that packaged scenarios have run against a downstream implementation or that this reference grants legal, security, or accessibility certification.
Contract
- Authorize against the ownership record for upload, read, preview, share, and delete; possession of a URL or key is not authorization.
- Bound size, count, media type, decompression, processing time, and storage consumption before expensive work begins.
- Keep new or suspect objects quarantined until validation and scanning reach a terminal policy outcome.
- Generate object keys independently of user filenames and prevent filenames, MIME labels, and metadata from selecting executable behavior.
- Document component ownership and allowed dependency direction, including which data may cross each boundary.
- Make synchronous, asynchronous, and batch paths implement the same authority and state invariants.
- Create the ownership record and upload session before transfer, enforce declared and observed limits, and finalize only after integrity checks.
- Multipart retries bind to the same upload identity; abandoned parts and records follow a bounded, ownership-aware cleanup process.
- For the storage and security design variant, enforce this declared boundary: specifies object layout, metadata, isolation, validation, delivery, and threat controls for file upload.
Implementation guidance
- Start with the domain state and interface contract, then attach adapters, storage, queues, and provider-specific code.
- Model File upload inputs, outputs, actors, states, invariants, side effects, and evidence before selecting framework or vendor details.
- Store the applicable File upload contract or policy version with material state so migrations, replay, and support decisions remain attributable.
- Introduce the path behind controlled rollout, compare expected and observed outcomes, and keep a tested recovery route until adoption evidence is complete.
Failure handling and safeguards
- Ambiguous processing or ownership leaves the object quarantined; cleanup requires ownership evidence and a recoverable grace period.
- Invalid or contradictory File upload state is rejected or quarantined; the implementation never guesses a value that broadens authority or duplicates an effect.
- Retries are bounded and use durable identity; after exhaustion, work reaches an inspectable terminal state with an accountable owner.
Verification and operations
- Exercise the contract through each adapter and prove that a failed dependency cannot bypass the authoritative boundary.
- Monitor File upload success, denial, validation failure, dependency failure, retry exhaustion, and recovery by contract version without sensitive payload dimensions.
- Re-run paired positive and negative fixtures after policy, schema, dependency, migration, or boundary changes and preserve the resulting evidence.
Adoption assumptions
- Names and values in the example are a concrete fixture, not universal defaults; adopters replace them through documented evidence and ownership.
- The adopting system can provide authenticated identity, durable operation or record versions, bounded telemetry, and a controlled path for change.
The executable-looking examples in this package are fixtures and acceptance contracts. Run the collection validator to check structure and metadata, then translate and execute the scenarios in the target repository before recording implementation evidence.