Core package for defining schemas, catalogs, and AI prompt generation for json-render. Use when working with @json-render/core, defining schemas, creating catalogs, or building JSON specs for UI/video generation.

@json render/core Core package for schema definition, catalog creation, and spec streaming. Key Concepts Schema : Defines the structure of specs and catalogs (use defineSchema ) Catalog : Maps component/action names to their definitions (use defineCatalog ) Spec : JSON output from AI that conforms to the schema SpecStream : JSONL streaming format for progressive spec building Defining a Schema Creating a Catalog Generating AI Prompts SpecStream Utilities For streaming AI responses (JSONL patches): Dynamic Prop Expressions Any prop value can be a dynamic expression resolved at render time: { "$state": "/state/key" } reads a value from the state model (one way read) { "$bindState": "/path" } two way binding: reads from state and enables write back. Use on the natural value prop (value, checked, pressed, etc.) of form components. { "$bindItem": "field" } two way binding to a repeat item field. Use inside repeat scopes. { "$cond": <condition , "$then": <value , "$else": <value } evaluates a visibility condition and picks a branch { "$template": "Hello, ${/user/name}!" } interpolates ${/path} references with state values { "$computed": "fnName", "args": { "key": <expression } } calls a registered function with resolved args $cond uses the same syntax as visibility conditions ( $state , eq , neq , not , arrays for AND). $then and $else can themselves be expressions (recursive). Components do not use a statePath prop for two way binding. Instead, use { "$bindState": "/path" } on the natural value prop (e.g. value , checked , pressed ). State Watchers Elements can declare a watch field (top level, sibling of type/props/children) to trigger actions when state values change: Watchers only fire on value changes, not on initial render. Validation Built in validation functions: required , email , url , numeric , minLength , maxLength , min , max , pattern , matches , equalTo , lessThan , greaterThan , requiredIf . Cross field validation uses $state expressions in args: User Prompt Builder Build structured user prompts with optional spec refinement and state context: Available edit modes: "patch" (RFC 6902 JSON Patch), "merge" (RFC 7396 Merge Patch), "diff" (unified diff). Spec Validation Validate spec structure and auto fix common issues: Visibility Conditions Control element visibility with state based conditions. VisibilityContext is { stateModel: StateModel } . Built in Actions in Schema Schemas can declare builtInActions actions that are always available at runtime and auto injected into prompts: These appear in prompts as [built in] and don't require handlers in defineRegistry . StateStore The StateStore interface allows external state management libraries (Redux, Zustand, XState, etc.) to be plugged into json render renderers. The createStateStore factory creates a simple in memory implementation: The StateStore interface: get(path) , set(path, value) , update(updates) , getSnapshot() , subscribe(listener) . Key Exports Export Purpose defineSchema Create a new schema defineCatalog Create a catalog from schema createStateStore Create a framework agnostic in memory StateStore resolvePropValue Resolve a single prop expression against data resolveElementProps Resolve all prop expressions in an element buildUserPrompt Build user prompts with refinement and state context buildEditUserPrompt Build user prompt for editing existing specs buildEditInstructions Generate prompt section for available edit modes isNonEmptySpec Check if spec has root and at least one element deepMergeSpec RFC 7396 deep merge (null deletes, arrays replace, objects recurse) diffToPatches Generate RFC 6902 JSON Patch operations from object diff EditMode Type: "patch" \ "merge" \ "diff" validateSpec Validate spec structure autoFixSpec Auto fix common spec issues; classifies fixes lossy/lossless, { lossy: false } withholds pruning createSpecStreamCompiler Stream JSONL patches into spec createJsonRenderTransform TransformStream separating text from JSONL in mixed streams parseSpecStreamLine Parse single JSONL line applySpecStreamPatch Apply patch to object StateStore Interface for plugging in external state management ComputedFunction Function signature for $computed expressions check TypeScript helpers for creating validation checks BuiltInAction Type for built in action definitions ( name + description ) ActionBinding Action binding type (includes preventDefault field)