Autocomplete: Requirements and relevance contract

Defines user intent, expected behavior, relevance rules, controls, inputs, outputs, and edge cases for autocomplete. 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 Autocomplete, adopt a versioned relevance contract evaluated on representative judgments. Make the user-visible promise, exclusions, authority, and failure response explicit while leaving measured thresholds as adoption choices. This requirements block focuses specifically on requirements and relevance contract. 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 Autocomplete actors, inputs, outputs, states, policy or schema versions, and externally visible outcomes required for the requirements and relevance contract focus of this requirements 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

• Define query interpretation, candidate eligibility, ranking signals, tie-breaking, filters, and fallback independently of one search engine.
• Apply tenant, entitlement, visibility, and deletion rules before returning hits, snippets, suggestions, facets, or total counts.
• Version source records, index documents, analyzers, ranking configuration, and evaluation sets so changes are attributable.
• Measure quality by intent segment and protect latency, error, freshness, and zero-result guardrails during relevance experiments.
• State which actor receives which outcome under each material state, including unavailable, unauthorized, empty, and partial conditions.
• Mark configurable limits and policies as choices with owners; do not present sample values as universal requirements.
• Cancel or ignore stale requests, preserve the typed query, and rank bounded suggestions by a versioned policy without exposing unauthorized entities or query history.
• Expose expanded state, active option, selection, loading, empty, and error behavior to keyboard and assistive technology while keeping text entry and option commitment distinct.
• For the requirements and relevance contract variant, enforce this declared boundary: defines user intent, expected behavior, relevance rules, controls, inputs, outputs, and edge cases for autocomplete.

Implementation guidance

• Review the contract with product, implementation, operations, security, and affected users before promoting it beyond review.
• Model Autocomplete inputs, outputs, actors, states, invariants, side effects, and evidence before selecting framework or vendor details.
• Store the applicable Autocomplete 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

• Invalid filters or unavailable required indexes return a clear bounded failure; optional enrichments may degrade only when declared non-authoritative.
• Invalid or contradictory Autocomplete 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

• Map each promise and exclusion to at least one observable scenario and confirm that no two states require contradictory outcomes.
• Monitor Autocomplete 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.