Safe rendering: Storage, safety, and operations
Specifies data structures, rendering, permissions, moderation controls, audit trail, testing, and operations for safe rendering. It fixes adoption boundaries and observable failure evidence while keeping 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 Safe rendering, adopt a versioned content record and moderation state machine. Implement the behavior through one authoritative write path, typed interfaces, explicit state, and idempotent side-effect handling. 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 Safe rendering actors, inputs, outputs, states, policy or schema versions, and externally visible outcomes described by this implementation 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
- Store original input separately from normalized or rendered output and identify the transformer and policy version used.
- Sanitize for the actual output context; parsing, Markdown conversion, and MIME labels do not make active content trusted.
- Authorize create, edit, publish, moderate, appeal, and delete actions independently and retain the material decision trail.
- Represent pending, allowed, restricted, rejected, appealed, and removed states explicitly rather than overloading visibility flags.
- Validate inputs once at the boundary and preserve the normalized representation used by downstream logic.
- Persist the business transition before or atomically with an outbox record; consumers deduplicate by durable operation identity.
- Parse untrusted content into a constrained representation, allowlist supported constructs, sanitize for the final output context, and render active formats in an isolated origin or worker.
- Block scripts, unsafe URLs, event handlers, external fetches, executable SVG, and resource abuse and version the parser and policy for reproducible reprocessing.
Implementation guidance
- Ship additive storage and interface changes first, backfill observably, then retire old paths after compatibility evidence.
- Model Safe rendering inputs, outputs, actors, states, invariants, side effects, and evidence before selecting framework or vendor details.
- Store the applicable Safe rendering 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
- Unsafe or unclassifiable content remains unavailable by default and enters a bounded review or rejection path.
- Invalid or contradictory Safe rendering 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
- Inject dependency failure before and after persistence and prove that retry converges on one externally visible outcome.
- Monitor Safe rendering 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.