State Management

Domain classification: design-engineering. Lifecycle: experimental.

Repository Boundary

State management is a Design Engineering topic, not a seventh domain. It owns consumer UI decisions about authoritative values, events, effects, reconciliation, and lifetime. Layout continues to own spatial composition; Motion owns optional presentation timing. Server transaction protocols, universal library rankings, and shared component implementations are outside this collection.

Reusable Method

Start with the decision tree, fill in the state brief, select the smallest relevant patterns, then compose a screen recipe. The verification matrix separates expected behavior from observed evidence.

한국어 검색 안내: 상태 관리, 상태 소유권, 파생 상태, 초안과 저장본, 비동기 요청 경합, URL 동기화, 상태 복원은 아래 패턴에서 찾을 수 있습니다.

Pattern Catalog

Category	Pattern	Failure prevented
Ownership and derivation	Single Owner And Controlled Inputs	Keep one authoritative value when several controls edit the same setting.
Ownership and derivation	Derived State From Authoritative Inputs	Prevent totals, filtered lists, and dirty flags from drifting away from their inputs.
Ownership and derivation	Selection By Stable Identity	Keep selection attached to an entity while a collection reorders or refreshes.
Editing and persistence	Draft And Persisted Baseline	Preserve editable work while distinguishing it from the last acknowledged saved value.
Editing and persistence	Submitted Snapshot And Save Acknowledgement	Keep later edits dirty when an earlier submitted snapshot finishes saving.
Editing and persistence	Unsaved Changes And Navigation	Make leaving an edited screen an explicit decision without losing the current draft.
Asynchronous consistency	Latest Request Wins	Prevent an older read response from replacing the result of a newer user intent.
Asynchronous consistency	Single Flight And Duplicate Submission	Apply an explicit policy to repeated activation of one pending operation.
Asynchronous consistency	Optimistic Overlay And Recovery	Show a speculative change while preserving an authoritative base for recovery.
Navigation and lifetime	URL State And History	Keep shareable screen state consistent across links, refresh, and browser history.
Navigation and lifetime	Identity Boundary And Reset	Prevent temporary state and pending outcomes from leaking across entity or account changes.
Navigation and lifetime	Versioned And Scoped State Restore	Restore persisted preferences only when their schema and ownership scope are valid.

Relationship To Existing Contracts

The Component Contract remains the public handoff for semantics, events, focus, and asynchronous ownership. Its save example remains in place. Worked Examples supplies existing product scenarios; these patterns make their mechanisms individually selectable.

This collection contains 12 patterns in four categories and four recipes. The composition matrix records essential and replaceable choices. Plain JavaScript examples are the local executable reference; framework adapters must preserve their declared invariants.

Opinionated Guidance

Start by locating the authoritative value and its lifetime. Introduce a shared store only when shared ownership or subscriptions require it. Keep remote data authority distinct from local cache ownership, and model request status separately from draft validity and persisted revision.

Platform-Specific Guidance

Choose native controls and platform navigation before adapters. URL parsing, storage access, focus recovery, and framework disposal each need target-runtime checks beyond the Node examples.

Unsupported Absolutes

Neither a reducer nor a state machine guarantees race freedom. No library is the default for this collection. Local executable examples do not establish backend, accessibility, or browser conformance.

Verification Contract

A reader should find a pattern from a failure symptom, identify its owner and minimal implementation, compose it into a screen, and locate a repeatable acceptance sequence. Run npm run test:state-management for the 12 local examples; record browser and backend checks separately.

Source, License, And Attribution

Locally authored synthesis and examples. No upstream implementation is copied. These experimental contracts describe consumer-owned behavior; review when a failure, ownership change, or platform change invalidates an assumption.

IA Navigation

Parent: Design Engineering. Next: Continue the state management route.