Context assembly: Pipeline implementation and metadata

Specifies processing stages, storage, metadata, interfaces, versioning, and dependencies for context assembly. 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 Context assembly, adopt a versioned source, transformation, index, and access-control lineage. 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 pipeline implementation and metadata. 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 Context assembly actors, inputs, outputs, states, policy or schema versions, and externally visible outcomes required for the pipeline implementation and metadata 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

• Preserve source identifier, version, location, access scope, parser, normalization, chunk, embedding, and index versions for every retrievable unit.
• Apply access filters before results, snippets, counts, caches, and model context are exposed; post-filtering alone is not sufficient.
• Quarantine parsing or transformation failures and prevent a partial artifact from silently replacing the last complete version.
• Evaluate retrieval and grounded-answer behavior on versioned representative cases, including conflicts, absence, staleness, and adversarial text.
• 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.
• Select every context item by task need, authority, provenance, access scope, trust, freshness, coverage, conflict, and token budget and preserve the source version and retrieval reason.
• Separate policy from untrusted data, order and delimit items deterministically, expose omissions and truncation, and key caches by the complete assembly policy, caller scope, sources, and versions.
• For the pipeline implementation and metadata variant, enforce this declared boundary: specifies processing stages, storage, metadata, interfaces, versioning, and dependencies for context assembly.

Implementation guidance

• Start with the domain state and interface contract, then attach adapters, storage, queues, and provider-specific code.
• Model Context assembly inputs, outputs, actors, states, invariants, side effects, and evidence before selecting framework or vendor details.
• Store the applicable Context assembly 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

• If provenance, access scope, or required content is missing, exclude the unit and expose a diagnosable coverage gap instead of fabricating completeness.
• Invalid or contradictory Context assembly 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 Context assembly 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.

References

• NIST AI 600-1, Generative AI Profile (applies as of 2026-09-08)