Defines the rules, intended use, allowed variation, examples, and consistency requirements for grid and containers. 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 Grid and containers, adopt versioned design tokens and component contracts shared by design and implementation. Define a deterministic user journey with visible state, reversible choices where possible, preserved input, and accessible recovery. 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 Grid and containers actors, inputs, outputs, states, policy or schema versions, and externally visible outcomes described by this ux 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
- Name tokens by semantic purpose; product code does not depend on raw palette, spacing, or typography values when a semantic token exists.
- Define allowed variants and states with accessibility behavior, content constraints, and responsive behavior in the same contract.
- Treat breaking token or component changes as migrations with ownership, compatibility notes, and measurable adoption.
- Use visual checks as change evidence, not as the sole test for semantics, keyboard operation, or accessible names.
- Show progress only while work is actually pending and prevent duplicate activation without hiding the user's committed intent.
- Use plain, action-specific messages that distinguish validation, permission, connectivity, conflict, and terminal failure.
- Define named container widths, gutters, column behavior, nesting, breakpoints, and content exceptions as tokens rather than page-local measurements.
- Test long text, zoom, narrow viewports, bidirectional layout, safe areas, and scrollbar changes without horizontal loss of required content.
Implementation guidance
- Prototype the longest, empty, slow, offline, denied, and assistive-technology paths before locking the happy-path layout.
- Model Grid and containers inputs, outputs, actors, states, invariants, side effects, and evidence before selecting framework or vendor details.
- Store the applicable Grid and containers 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
- An unknown token or variant fails visibly in development and uses a documented safe fallback in released clients.
- Invalid or contradictory Grid and containers 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
- Complete the journey with keyboard, touch, screen reader, narrow viewport, delayed network, and a recoverable server error.
- Monitor Grid and containers 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.