Core Package Development

The core package (packages/core/) is dependency-free and handles all DSL processing.

Data Flow

DSL (YAML input) → validate() → normalize() → IR → diff() → Patch

Key Files

| File | Purpose | Exports | |------|---------|---------| | types.ts | Type definitions | DSL, IR, Patch, WebSocket protocol | | validate.ts | YAML validation | validate(dsl): ValidationResult | | normalize.ts | DSL → IR conversion | normalize(dsl): IRDocument | | diff.ts | IR diff calculation | diff(prev, next): Patch |

Type Hierarchy

DSL Types (user input)      IR Types (normalized)
─────────────────────       ────────────────────
DSLDocument                 IRDocument
  ├─ version: number          ├─ version: number
  ├─ docId: string            ├─ docId: string
  ├─ title?: string           ├─ title: string
  ├─ nodes: DSLNode[]         ├─ nodes: Record<string, IRNode>
  └─ edges?: DSLEdge[]        └─ edges: Record<string, IREdge>

DSLNode                     IRNode
  ├─ id: string               ├─ id: string
  ├─ provider: string         ├─ provider: string
  ├─ kind: string             ├─ kind: string
  ├─ label?: string           ├─ label: string (default: id)
  ├─ parent?: string          ├─ parent: string | null
  └─ layout: DSLLayout        └─ layout: { x, y, w, h }

DSLEdge                     IREdge
  ├─ id: string               ├─ id: string
  ├─ from: string             ├─ from: string
  ├─ to: string               ├─ to: string
  └─ label?: string           └─ label: string (default: "")

Patch Operations

typescript
type PatchOp =
  | { op: "upsertNode"; node: IRNode }
  | { op: "removeNode"; id: string }
  | { op: "upsertEdge"; edge: IREdge }
  | { op: "removeEdge"; id: string };

interface Patch {
  baseRev: number;
  nextRev: number;
  ops: PatchOp[];
}

WebSocket Protocol Types

typescript
// Plugin → CLI
interface HelloMessage {
  type: "hello";
  docId: string;
  secret?: string;
}

interface RequestFullMessage {
  type: "requestFull";
  docId: string;
}

// CLI → Plugin
interface FullMessage {
  type: "full";
  rev: number;
  ir: IRDocument;
}

interface PatchMessage {
  type: "patch";
  baseRev: number;
  nextRev: number;
  ops: PatchOp[];
}

interface ErrorMessage {
  type: "error";
  message: string;
}

Development Workflow

1. Modify types → Update types.ts
2. Update validation → Ensure validate.ts catches invalid input
3. Update normalization → Handle new fields/defaults in normalize.ts
4. Update diff → Handle new patch scenarios in diff.ts
5. Add tests → Co-located *.test.ts files
6. Run tests → bun test packages/core/

Testing

bash
# All core tests
bun test packages/core/

# Specific test file
bun test packages/core/src/diff.test.ts
bun test packages/core/src/validate.test.ts
bun test packages/core/src/normalize.test.ts

# Watch mode
bun test --watch packages/core/

Common Patterns

Adding a new node property

1. Add to DSLNode and IRNode in types.ts
2. Add validation in validate.ts
3. Add default value handling in normalize.ts
4. Update diff logic if property affects equality
5. Add test cases for validation, normalization, and diff

Adding a new edge property

1. Add to DSLEdge and IREdge in types.ts
2. Add validation in validate.ts
3. Add default value handling in normalize.ts
4. Update diff logic for edge equality check
5. Add test cases