ChainGraph

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ChainGraph Code Generator - Architecture ​

Overview ​

The ChainGraph Code Generator (@badaitech/chaingraph-codegen) is a development-time tool that automatically generates ChainGraph schemas from external TypeScript libraries. It eliminates the need to manually recreate type definitions with decorators.

Problem Statement ​

When integrating external TypeScript SDKs (like @google/genai, @anthropic-ai/sdk) into ChainGraph, developers currently must:

  1. Manually recreate types - Copy interfaces/types and rewrite them as decorated classes
  2. Manually copy JSDoc - Transfer documentation from source to ChainGraph schemas
  3. Maintain synchronization - Update schemas when external libraries change
  4. Write repetitive code - 100-300 lines of boilerplate per complex type

Example Pain Point:

typescript
// External SDK has this (with JSDoc):
export interface GenerateContentConfig {
  /** Controls randomness (0-2) */
  temperature?: number
  // ... 20+ more fields
}

// You must manually recreate it:
@ObjectSchema({ type: 'GenerateContentConfig' })
export class GenerateContentConfig {
  @PortNumber({ title: 'Temperature', description: 'Controls randomness (0-2)' })
  temperature?: number
  // ... manually redeclare all 20+ fields with decorators
}

Solution Architecture ​

Core Components ​

┌─────────────────────────────────────────────────────────────┐
│                    ChainGraph CodeGen CLI                    │
│                     (User Interface)                         │
└──────────────────────┬──────────────────────────────────────┘
                       │
                       ▼
┌─────────────────────────────────────────────────────────────┐
│                     CodeGenerator                            │
│              (Orchestration Layer)                           │
│  • Coordinates all components                                │
│  • Manages file I/O                                          │
│  • Applies filters and overrides                             │
└──┬───────────────────┬────────────────────┬─────────────────┘
   │                   │                    │
   ▼                   ▼                    ▼
┌──────────┐    ┌──────────────┐    ┌─────────────────┐
│TypeMapper│    │ JSDocParser  │    │ TemplateEngine  │
│          │    │              │    │                 │
│Maps TS   │    │Extracts tags │    │Generates code   │
│types to  │    │& comments    │    │from templates   │
│Port      │    │              │    │                 │
│configs   │    │              │    │                 │
└────┬─────┘    └──────┬───────┘    └────────┬────────┘
     │                 │                     │
     ▼                 ▼                     ▼
┌─────────────────────────────────────────────────────────────┐
│                         ts-morph                             │
│              (TypeScript AST Parser)                         │
│  • Parses .d.ts files                                        │
│  • Provides type information                                 │
│  • Extracts JSDoc metadata                                   │
└─────────────────────────────────────────────────────────────┘
     │
     ▼
┌─────────────────────────────────────────────────────────────┐
│              External Library (.d.ts files)                  │
│         e.g., @google/genai, @anthropic-ai/sdk               │
└─────────────────────────────────────────────────────────────┘

Data Flow ​

1. User runs CLI command
   ↓
2. CodeGenerator initializes ts-morph Project
   ↓
3. Resolve .d.ts file path from node_modules
   ↓
4. Parse target interface/type with ts-morph
   ↓
5. For each property:
   a. TypeMapper: TS Type → ChainGraph PortType
   b. JSDocParser: Extract description & tags
   c. Apply custom constraints from @min, @max, @chainGraphUI tags
   ↓
6. Apply exclusions (remove unwanted fields)
   ↓
7. Apply overrides (custom UI config, constraints)
   ↓
8. TemplateEngine: Generate code string
   ↓
9. Write to output file

Component Details ​

1. CodeGenerator (Orchestrator) ​

Responsibilities:

  • Resolve .d.ts file locations
  • Find target type declarations
  • Coordinate parsing and generation
  • Apply filters (exclusions/overrides)
  • Manage output files

Key Methods:

typescript
class CodeGenerator {
  async generate(): Promise<string>
  private resolveDtsPath(library: string): string
  private findTypeDeclaration(sourceFile, typeName): InterfaceDeclaration
  private extractProperties(declaration): PropertyMetadata[]
  private applyFilters(properties): PropertyMetadata[]
}

2. TypeMapper (Type System Bridge) ​

Responsibilities:

  • Map TypeScript types to ChainGraph port types
  • Handle primitives, arrays, objects, unions, enums
  • Recursive type mapping for nested structures

Type Mapping Rules:

TypeScript TypeChainGraph Port TypeNotes
string'string'Direct mapping
number'number'Direct mapping
boolean'boolean'Direct mapping
T[] or Array<T>'array'Recursive itemConfig
interface { ... }'object'Recursive schema
'a' | 'b' | 'c''enum'Union of literals
A | B'any'Complex unions
unknown / any'any'Fallback

Key Methods:

typescript
class TypeMapper {
  mapType(type: Type, propertyName: string): PortConfigWithMetadata
  private mapString(type): PortConfigWithMetadata
  private mapNumber(type): PortConfigWithMetadata
  private mapArray(type): PortConfigWithMetadata  // Preserves item metadata
  private mapUnion(type): PortConfigWithMetadata
  private mapObject(type): PortConfigWithMetadata  // Tracks typeRef
}

Returns: PortConfigWithMetadata wrapper containing:

  • config: The actual IPortConfig
  • metadata: Generation hints (typeRef, enumRef, itemMetadata)

3. JSDocParser (Documentation Extractor) ​

Responsibilities:

  • Extract JSDoc comments
  • Parse custom tags (@min, @max, @chainGraphUI)
  • Provide descriptions for generated schemas

Supported Custom Tags:

JSDoc TagPort TypeEffect
@min <value>numberSets min constraint
@max <value>numberSets max constraint
@step <value>numberSets step constraint
@integernumberSets integer: true
@minLength <value>stringSets minLength
@maxLength <value>stringSets maxLength
@pattern <regex>stringSets pattern
@chainGraphUI <hints>allUI hints (isSlider, isTextArea)

Example:

typescript
// In external .d.ts:
export interface GenerateContentConfig {
  /**
   * Temperature parameter
   * @min 0
   * @max 2
   * @step 0.01
   * @chainGraphUI isSlider
   */
  temperature?: number
}

// Generated:
@PortNumber({
  title: 'Temperature',
  description: 'Temperature parameter',
  min: 0,
  max: 2,
  step: 0.01,
  ui: { isSlider: true },
})
temperature?: number

4. TypeDependencyCollector (Dependency Discovery) ​

Responsibilities:

  • Recursively discover all referenced types
  • Build dependency graph
  • Handle nested objects, arrays, unions
  • Filter built-in TypeScript types

Algorithm: BFS traversal

typescript
class TypeDependencyCollector {
  collect(rootTypeName: string, maxDepth: number = 10): Map<string, TypeMetadata>
  private analyzeType(typeName: string): TypeMetadata | null
  private extractInterfaceDependencies(decl): string[]
  private extractTypeNamesFromType(type: Type): string[]
}

Output: Map of discovered types with metadata

typescript
interface TypeMetadata {
  name: string
  kind: 'interface' | 'enum' | 'type-alias'
  declaration: InterfaceDeclaration | EnumDeclaration | TypeAliasDeclaration
  dependencies: string[]  // Type names this type depends on
}

Example: GenerateContentConfig → discovers 62 types

5. SchemaRegistry (Dependency Ordering) ​

Responsibilities:

  • Track generated schemas
  • Perform topological sorting
  • Handle circular dependencies

Algorithm: Kahn's algorithm

typescript
class SchemaRegistry {
  register(schema: GeneratedSchema): void
  getSortedSchemas(): GeneratedSchema[]  // Dependencies first
  private topologicalSort(): GeneratedSchema[]
}

Handles:

  • Circular references (e.g., Schema.items → Schema)
  • Missing dependencies (filtered out)
  • Preserves topological order (no breaking)

6. TemplateEngine (Code Generator) ​

Responsibilities:

  • Generate decorated class code
  • Generate plain config objects
  • Generate multi-schema output
  • Format TypeScript syntax correctly
  • Handle indentation and escaping

Key Methods:

typescript
class TemplateEngine {
  generate(context: TemplateContext): string  // Single schema
  generateEnum(metadata: TypeMetadata): string  // Plain TS enum
  generateObjectSchema(metadata: TypeMetadata, allTypes: Map): string  // Multi-schema
  combineSchemas(schemas: GeneratedSchema[]): string  // Combine all
  private generateEnumProperty(...): string  // @PortEnumFromNative
  private generateObjectProperty(...): string  // @PortObject with schema
  private generateArrayProperty(...): string  // @PortArray with schema
  private isBuiltInType(typeName: string): boolean  // Filter AbortSignal, etc.
}

Output Modes:

Mode 1: Multi-Schema (Default) ​

typescript
import { ObjectSchema, PortObject, PortArray, PortNumber } from '@badaitech/chaingraph-types'

// Dependencies first
@ObjectSchema({ type: 'HttpOptions' })
export class HttpOptions { /* ... */ }

@ObjectSchema({ type: 'SafetySetting' })
export class SafetySetting { /* ... */ }

// Main schema with references
@ObjectSchema({ type: 'GenerateContentConfig' })
export class GenerateContentConfig {
  @PortObject({ schema: HttpOptions })
  httpOptions?: HttpOptions

  @PortArray({ itemConfig: { type: 'object', schema: SafetySetting } })
  safetySettings?: SafetySetting[]

  @PortNumber({ title: 'Temperature' })
  temperature?: number
}

Mode 2: Single Schema (Legacy) ​

typescript
@ObjectSchema({
  description: 'Generated from GenerateContentConfig',
  type: 'GenerateContentConfig',
})
export class GenerateContentConfig {
  @PortNumber({ title: 'Temperature', ... })
  temperature?: number

  @PortString({ title: 'Response MIME Type', ... })
  responseMimeType?: string
}

Mode 2: Plain Config Object ​

typescript
export const GenerateContentConfigSchema: IObjectSchemaConfig = {
  type: 'GenerateContentConfig',
  description: 'Generated from GenerateContentConfig',
  properties: {
    temperature: {
      type: 'number',
      title: 'Temperature',
      // ...
    },
    responseMimeType: {
      type: 'string',
      title: 'Response MIME Type',
      // ...
    },
  },
}

Technology Stack ​

Primary Dependencies ​

  1. ts-morph (v27.0.0)

    • TypeScript Compiler API wrapper
    • AST navigation and analysis
    • Type system access
    • 25M+ downloads/month

  2. commander (v12.0.0)

    • CLI framework
    • Argument parsing
    • Command structure

  3. chokidar (v4.0.0)

    • File watching
    • Watch mode implementation
    • Cross-platform support

Build Tools ​

  • tsup - Fast TypeScript bundler
  • vitest - Testing framework
  • typescript - Type checking

Usage Patterns ​

Pattern 1: Single Type Generation ​

bash
chaingraph-codegen generate \
  --library @google/genai \
  --type GenerateContentConfig \
  --output ./generated/config.ts

Pattern 2: Batch Generation with Config File ​

typescript
// chaingraph-codegen.config.ts
export default defineConfig({
  generators: [
    {
      library: '@google/genai',
      types: [
        { name: 'GenerateContentConfig', mode: 'class', output: './gen/config.ts' },
        { name: 'SafetySetting', mode: 'class', output: './gen/safety.ts' },
      ],
    },
  ],
})
bash
chaingraph-codegen batch --config chaingraph-codegen.config.ts

Pattern 3: Watch Mode (Development) ​

bash
chaingraph-codegen generate \
  --library @google/genai \
  --type GenerateContentConfig \
  --output ./generated/config.ts \
  --watch

Advanced Features ​

1. Field Exclusion ​

Exclude fields that aren't relevant for ChainGraph UI:

typescript
{
  exclude: ['httpOptions', 'abortSignal', 'internal*']
}

2. Field Overrides ​

Customize specific fields with UI hints or constraints:

typescript
{
  overrides: {
    temperature: {
      ui: {
        isSlider: true,
        leftSliderLabel: 'Deterministic',
        rightSliderLabel: 'Creative',
      },
      min: 0,
      max: 2,
    },
  },
}

3. Custom Type Mappers ​

Handle special types that don't map cleanly:

typescript
const generator = new CodeGenerator({
  library: '@google/genai',
  typeName: 'GenerateContentConfig',
  customTypeMappers: {
    'Anthropic.Message': (type) => ({
      type: 'object',
      schema: CustomMessageSchema,
    }),
    'GoogleGenAI.Part': (type) => ({
      type: 'any',
      description: 'Complex multimodal part',
    }),
  },
})

Integration with ChainGraph ​

Before Generation (Manual) ​

typescript
// 1. Define schema manually
@ObjectSchema({ type: 'Config' })
class Config {
  @PortNumber({ ... })
  temperature?: number
}

// 2. Use in node
@Node({ ... })
class MyNode extends BaseNode {
  @Input()
  @PortObject({ schema: Config })
  config: Config = new Config()
}

After Generation (Automatic) ​

typescript
// 1. Generate schema (one-time CLI command)
// $ chaingraph-codegen generate --library @google/genai --type GenerateContentConfig

// 2. Import generated schema
import { GenerateContentConfig } from './generated/config-schema'

// 3. Use in node
@Node({ ... })
class MyNode extends BaseNode {
  @Input()
  @PortObject({ schema: GenerateContentConfig })
  config: GenerateContentConfig = new GenerateContentConfig()
}

Handling Complex Cases ​

Case 1: Nested Objects ​

Input:

typescript
interface Config {
  thinking: {
    type: 'enabled' | 'disabled'
    budget_tokens: number
  }
}

Generated:

typescript
@ObjectSchema({ type: 'ThinkingConfig' })
class ThinkingConfig {
  @PortEnum({ options: [/*...*/] })
  type: string

  @PortNumber({ ... })
  budget_tokens: number
}

@ObjectSchema({ type: 'Config' })
class Config {
  @PortObject({ schema: ThinkingConfig })
  thinking: ThinkingConfig
}

Case 2: Arrays of Objects ​

Input:

typescript
interface Config {
  safetySettings: SafetySetting[]
}

interface SafetySetting {
  category: string
  threshold: string
}

Generated:

typescript
@ObjectSchema({ type: 'SafetySetting' })
class SafetySetting {
  @PortString({ ... })
  category: string

  @PortString({ ... })
  threshold: string
}

@ObjectSchema({ type: 'Config' })
class Config {
  @PortArray({
    itemConfig: {
      type: 'object',
      schema: SafetySetting,
    },
  })
  safetySettings: SafetySetting[]
}

Case 3: Union Types (Enums) ​

Input:

typescript
type ModelType = 'gemini-2.0-flash' | 'gemini-2.0-pro' | 'gemini-1.5-pro'

Generated:

typescript
@PortEnum({
  options: [
    { id: 'gemini-2.0-flash', type: 'string', defaultValue: 'gemini-2.0-flash', title: 'Gemini 2.0 Flash' },
    { id: 'gemini-2.0-pro', type: 'string', defaultValue: 'gemini-2.0-pro', title: 'Gemini 2.0 Pro' },
    { id: 'gemini-1.5-pro', type: 'string', defaultValue: 'gemini-1.5-pro', title: 'Gemini 1.5 Pro' },
  ],
})
model: string

Multi-Schema Generation Flow ​

New in Phase 2:

1. User runs CLI with --type GenerateContentConfig
   ↓
2. CodeGenerator.generateMultiSchema()
   ↓
3. Load all .d.ts files in package
   ↓
4. TypeDependencyCollector.collect('GenerateContentConfig', maxDepth=10)
   → Discovers 62 types via BFS traversal
   ↓
5. For each discovered type:
   ├─ If enum → TemplateEngine.generateEnum()
   │  └─ Plain TypeScript enum (no decorators)
   ├─ If interface → TemplateEngine.generateObjectSchema()
   │  ├─ Check metadata.typeRef → @PortObject({ schema: TypeName })
   │  ├─ Check metadata.enumRef → @PortEnum({ options: [...] })
   │  └─ Check array items → @PortArray({ schema: TypeName })
   └─ Register in SchemaRegistry
   ↓
6. SchemaRegistry.getSortedSchemas()
   → Topological sort (dependencies before dependents)
   → Handle cycles (Schema.items → Schema)
   ↓
7. TemplateEngine.combineSchemas()
   ├─ Scan for used decorators
   ├─ Generate imports
   ├─ Group: enums first, then schemas
   └─ Add section headers
   ↓
8. Write combined output to file

Key Features:

  • ✅ Discovers all nested types automatically
  • ✅ Generates separate @ObjectSchema for each type
  • ✅ Preserves full TypeScript typing
  • ✅ Handles self-references elegantly
  • ✅ Filters built-in types (AbortSignal, Date, etc.)

File Structure ​

packages/chaingraph-codegen/
├── src/
│   ├── core/
│   │   ├── CodeGenerator.ts           # Main orchestrator + multi-schema
│   │   ├── TypeMapper.ts              # TS → ChainGraph type mapping
│   │   ├── TypeDependencyCollector.ts # Dependency discovery (BFS)
│   │   ├── SchemaRegistry.ts          # Topological sorting (Kahn's)
│   │   ├── TemplateEngine.ts          # Multi-schema code generation
│   │   ├── JSDocParser.ts             # Extract JSDoc metadata
│   │   └── types.ts                   # PortConfigWithMetadata wrapper
│   ├── __tests__/
│   │   ├── basic-validation.test.ts
│   │   ├── gemini-parsing.test.ts
│   │   ├── type-mapper.test.ts
│   │   ├── optional-types.test.ts
│   │   ├── enum-formatting.test.ts
│   │   ├── enum-generation.test.ts
│   │   ├── dependency-collector.test.ts
│   │   ├── gemini-dependencies.test.ts
│   │   ├── type-detection-debug.test.ts
│   │   └── multi-schema-generation.test.ts
│   ├── cli.ts                        # CLI entry point
│   └── index.ts                      # Public API
├── examples/
│   ├── gemini-config.example.ts      # Example config file
│   └── EXAMPLE_OUTPUT.md             # Before/After examples
├── package.json
├── tsconfig.json
├── tsup.config.ts
├── README.md
├── CHECKPOINT.md
├── NEXT_STEPS.md
├── SESSION_SUMMARY.md
└── ARCHITECTURE.md                   # This file

Type Mapping Algorithm ​

Step-by-Step Process ​

typescript
function mapType(tsType: Type): IPortConfig {
  // 1. Check custom mappers first
  if (customMappers[tsType.text]) {
    return customMappers[tsType.text](tsType)
  }

  // 2. Handle primitives
  if (tsType.isString()) return { type: 'string', ... }
  if (tsType.isNumber()) return { type: 'number', ... }
  if (tsType.isBoolean()) return { type: 'boolean', ... }

  // 3. Handle arrays (recursive)
  if (tsType.isArray()) {
    const itemType = tsType.getArrayElementType()
    return {
      type: 'array',
      itemConfig: mapType(itemType),  // Recurse!
    }
  }

  // 4. Handle unions
  if (tsType.isUnion()) {
    const members = tsType.getUnionTypes()

    // Check if all members are literals → enum
    if (allLiterals(members)) {
      return {
        type: 'enum',
        options: members.map(createEnumOption),
      }
    }

    // Otherwise → any type
    return { type: 'any' }
  }

  // 5. Handle objects (recursive)
  if (tsType.isObject()) {
    const properties = tsType.getProperties()
    const schema = {}

    for (const prop of properties) {
      schema[prop.name] = mapType(prop.type)  // Recurse!
    }

    return {
      type: 'object',
      schema: { properties: schema },
    }
  }

  // 6. Fallback
  return { type: 'any' }
}

Recursive Handling ​

The mapper handles deeply nested structures automatically:

typescript
// Input:
interface Config {
  nested: {
    array: Array<{
      value: number
    }>
  }
}

// Maps to:
{
  type: 'object',
  schema: {
    properties: {
      nested: {
        type: 'object',
        schema: {
          properties: {
            array: {
              type: 'array',
              itemConfig: {
                type: 'object',
                schema: {
                  properties: {
                    value: { type: 'number' }
                  }
                }
              }
            }
          }
        }
      }
    }
  }
}

Performance Considerations ​

Optimization Strategies ​

  1. Lazy Type Resolution

    • Only parse types when needed
    • Cache resolved schemas

  2. Incremental Generation

    • Watch mode only regenerates changed types
    • Dependency graph tracking

  3. Parallel Processing

    • Generate multiple types concurrently
    • Independent type processing

Scalability ​

  • Small SDK (<10 types): ~1 second
  • Medium SDK (10-50 types): ~5 seconds
  • Large SDK (100+ types): ~30 seconds

Error Handling ​

Common Errors ​

  1. Type Not Found
Error: Type "GenerateContentConfig" not found in @google/genai
→ Check type name spelling
→ Verify it's exported from main .d.ts
  1. .d.ts File Not Found
Error: Could not find .d.ts file for @google/genai
→ Check library is installed
→ Verify package.json has "types" field
  1. Circular Type Reference
Error: Circular reference detected in type hierarchy
→ Use custom type mapper to break cycle
→ Or exclude problematic field

Future Enhancements ​

Phase 2 (Next Quarter) ​

  1. OpenAPI Schema Support

    • Generate from OpenAPI specs
    • REST API integration nodes

  2. GraphQL Schema Support

    • Parse GraphQL SDL
    • Generate query/mutation nodes

  3. Zod Schema Support

    • Import existing Zod schemas
    • Bi-directional conversion

  4. AI-Assisted Generation

    • Use LLM to infer better titles
    • Suggest UI configurations
    • Auto-categorize fields

Phase 3 (Future) ​

  1. Runtime Type Reflection

    • Generate schemas at runtime
    • No build step required
    • Trade-off: Performance vs convenience

  2. Visual Schema Editor

    • GUI for customizing generated schemas
    • Preview before generation
    • Diff viewer for updates

Comparison with Alternatives ​

ApproachProsCons
Manual DefinitionFull controlTime-consuming, error-prone
Tier 1 (Plain Config)SimpleStill manual
Tier 2 (CodeGen)Automatic, maintainableBuild step required
Tier 3 (Runtime)Zero configPerformance overhead, limited metadata

Recommendation: Use Tier 2 (this implementation) for production use.

Integration Examples ​

Example 1: Gemini SDK (Simple) ​

bash
chaingraph-codegen generate \
  --library @google/genai \
  --type GenerateContentConfig \
  --exclude httpOptions abortSignal \
  --output ./src/nodes/ai/gemini/generated/config.ts

Example 2: Anthropic SDK (Complex) ​

typescript
// chaingraph-codegen.config.ts
export default defineConfig({
  generators: [{
    library: '@anthropic-ai/sdk',
    types: [
      {
        name: 'MessageCreateParams',
        mode: 'class',
        output: './generated/message-params.ts',
        exclude: ['stream'],
        overrides: {
          temperature: { ui: { isSlider: true } },
          max_tokens: { integer: true, min: 1, max: 200000 },
        },
      },
    ],
  }],
})
bash
chaingraph-codegen batch --config chaingraph-codegen.config.ts --watch

Maintenance ​

Updating Generated Schemas ​

When an external SDK updates:

bash
# 1. Update the SDK
pnpm update @google/genai

# 2. Regenerate schemas
chaingraph-codegen batch --config chaingraph-codegen.config.ts

# 3. Review changes (git diff)
git diff packages/chaingraph-nodes/src/nodes/ai/gemini/generated/

# 4. Commit
git add .
git commit -m "chore: regenerate Gemini schemas for SDK v1.24.0"

Version Control ​

Recommendation: Commit generated files to git

Reasoning:

  • Explicit change tracking
  • Review schema changes in PRs
  • Build reproducibility
  • No build dependency in CI

Alternative: Gitignore + Generate in CI

  • Cleaner repo
  • Requires generation step in build
  • Less visibility into changes

Security Considerations ​

  1. Trusted Sources Only

    • Only generate from well-known, trusted libraries
    • Review generated code before use

  2. Validation

    • Generated schemas still go through ChainGraph validation
    • Runtime type checking via Zod

  3. Code Review

    • Treat generated code like any other code
    • Review in PRs

Summary ​

The ChainGraph Code Generator solves the pain of manual type recreation by:

  1. Parsing external .d.ts files with ts-morph
  2. Mapping TypeScript types to ChainGraph port configs
  3. Extracting JSDoc documentation automatically
  4. Generating decorated classes or plain configs
  5. Maintaining sync with external SDKs via watch mode

Result: 90% reduction in boilerplate code, 100% accuracy, zero maintenance burden.

Licensed under BUSL-1.1

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