Add New Agent Support

You are adding a new agent support to agent-command-sync. Follow this guide step by step.

Architecture

All conversions use a hub-and-spoke architecture via SemanticIR. No pairwise converters are needed — implementing a single pair of toIR() / fromIR() automatically enables bidirectional conversion with all existing agents.

Source Format → Parser → toIR() → SemanticIR → fromIR() → Target Format

Agent-specific logic is colocated in a single agent class that implements the AgentDefinition interface and is centrally managed via AGENT_REGISTRY: Record<ProductType, AgentDefinition>. Adding a value to PRODUCT_TYPES will trigger a compile error if the registry is missing a corresponding entry.

Step 1: Type Definitions

src/types/intermediate.ts

Add the new agent name to the PRODUCT_TYPES array. ProductType is automatically derived.

// Before
export const PRODUCT_TYPES = ["claude", "gemini", "codex", "opencode"] as const;
// After
export const PRODUCT_TYPES = ["claude", "gemini", "codex", "opencode", "newagent"] as const;

This change alone will trigger a compile error if AGENT_REGISTRY is missing an entry for the new agent.

src/types/command.ts

Add an agent-specific command type.

export interface NewAgentCommand {
  // Define according to the agent's command file structure
  frontmatter?: Record<string, unknown>;  // If YAML frontmatter is used
  content: string;
  filePath: string;
}

src/types/skill.ts

Add an agent-specific skill type. The standard approach is to extend SkillBase.

export interface NewAgentSkill extends SkillBase {
  frontmatter: {
    name?: string;
    description?: string;
    [key: string]: unknown;
  };
  // Add agent-specific settings here
}

src/types/index.ts uses wildcard exports (export *), so adding types to command.ts / skill.ts automatically re-exports them. No changes needed.

Step 2: Agent Class

src/agents/newagent.ts (new file)

Create a single agent class that implements all interfaces: AgentConfig, BodyParser, CommandParser, CommandConverter, SkillParser, and SkillConverter. Each agent has one file (e.g., claude.ts, gemini.ts, codex.ts, opencode.ts).

import type { BodySegment } from "../types/body-segment.js";
import type { NewAgentCommand, NewAgentSkill } from "../types/index.js";
import type { ConverterOptions, SemanticIR } from "../types/semantic-ir.js";
import { parseBody, serializeBody } from "../utils/body-segment-utils.js";
import type {
  AgentDefinition,
  BodyParser,
  CommandConverter,
  CommandParser,
  SkillConverter,
  SkillParser,
} from "./types.js";

export class NewAgentAgent
  implements
    AgentDefinition,
    BodyParser,
    CommandParser<NewAgentCommand>,
    CommandConverter<NewAgentCommand>,
    SkillParser<NewAgentSkill>,
    SkillConverter<NewAgentSkill>
{
  // ── AgentConfig ───────────────────────────────────────────────────

  readonly displayName = "NewAgent";       // human-readable name (used in CLI help)
  readonly dirs = {
    commandSubdir: "commands",             // or "prompts" etc.
    skillSubdir: "skills",
    projectBase: ".newagent",              // project root relative
    userDefault: ".newagent",              // homedir relative (e.g. ".config/newagent")
  };
  readonly fileExtension = ".md";          // or ".toml"

  // ── BodyParser ────────────────────────────────────────────────────

  parseBody(body: string): BodySegment[] {
    // If using Claude-syntax placeholders, import from _claude-syntax-body-patterns.ts:
    //   import { CLAUDE_SYNTAX_PATTERNS } from "./_claude-syntax-body-patterns.js";
    //   return parseBody(body, CLAUDE_SYNTAX_PATTERNS);
    // If using unique syntax, define custom PatternDef[] in this file.
    return parseBody(body, /* patterns */);
  }

  serializeBody(segments: BodySegment[]): string {
    // If using Claude-syntax placeholders:
    //   import { CLAUDE_SYNTAX_SERIALIZERS } from "./_claude-syntax-body-patterns.js";
    //   return serializeBody(segments, CLAUDE_SYNTAX_SERIALIZERS);
    // Optionally pass an UNSUPPORTED set as the third argument.
    return serializeBody(segments, /* serializers */);
  }

  // ── CommandParser ─────────────────────────────────────────────────

  async parseCommand(filePath: string): Promise<NewAgentCommand> {
    // Read and parse a command file into the agent-specific type
  }

  validateCommand(data: NewAgentCommand): boolean {
    // Validate the data
  }

  stringifyCommand(command: NewAgentCommand): string {
    // Convert the agent-specific type to file content string
  }

  // ── CommandConverter ──────────────────────────────────────────────

  commandToIR(source: NewAgentCommand, _options?: ConverterOptions): SemanticIR {
    // description → ir.semantic.description
    // body → this.parseBody(...)
    // other fields → ir.extras
  }

  commandFromIR(ir: SemanticIR, options?: ConverterOptions): NewAgentCommand {
    // ir.semantic.description → agent-specific field
    // ir.body → this.serializeBody(...)
    // ir.extras → pass through (or skip with removeUnsupported)
  }

  // ── SkillParser ───────────────────────────────────────────────────

  async parseSkill(dirPath: string): Promise<NewAgentSkill> {
    // Read from a skill directory (SKILL.md + support files)
  }

  validateSkill(data: NewAgentSkill): boolean {
    // Validate the data
  }

  stringifySkill(skill: NewAgentSkill): string {
    // Convert to SKILL.md format
  }

  async writeSkillToDirectory(
    skill: NewAgentSkill,
    sourceDirPath: string,
    targetDir: string,
  ): Promise<void> {
    // Write a skill to a directory (SKILL.md + support files)
  }

  // ── SkillConverter ────────────────────────────────────────────────

  skillToIR(source: NewAgentSkill, _options?: ConverterOptions): SemanticIR {
    // Similar to commandToIR, with additional handling for:
    // - modelInvocationEnabled semantic property (from disable-model-invocation)
  }

  skillFromIR(ir: SemanticIR, options?: ConverterOptions): NewAgentSkill {
    // Similar to commandFromIR, with:
    // - CLAUDE_SKILL_FIELDS for removeUnsupported filtering
    // - Extras are passed through as-is (no prefixing)
  }
}

export function createNewAgentAgent(): AgentDefinition {
  return new NewAgentAgent();
}

Body patterns:

• If the syntax is the same as Claude/Codex/OpenCode: import CLAUDE_SYNTAX_PATTERNS and CLAUDE_SYNTAX_SERIALIZERS from _claude-syntax-body-patterns.ts
• If the syntax is unique: define custom PatternDef[] and PlaceholderSerializers in the agent file (see gemini.ts for an example)

CLAUDE_COMMAND_FIELDS: Define the list of fields not supported by the target.

// Example: OpenCode supports model, so only allowed-tools and argument-hint
const CLAUDE_COMMAND_FIELDS = ["allowed-tools", "argument-hint"] as const;

// Example: Codex doesn't support model either, so three fields
const CLAUDE_COMMAND_FIELDS = ["allowed-tools", "argument-hint", "model"] as const;

CLAUDE_SKILL_FIELDS: List of Claude-specific skill fields not supported by the target. These fields are passed through as-is when removeUnsupported=false (default), and removed when removeUnsupported=true. Include disable-model-invocation in this list. Additional considerations:

• modelInvocationEnabled: A semantic property. Bidirectionally converted with Claude's disable-model-invocation (inverted) and Codex's allow_implicit_invocation

Skill parser checklist:

• Verify SKILL.md existence with isSkillDirectory()
• Collect support files with collectSupportFiles()
• If agent-specific config files exist, parse/write them individually (e.g., Codex's agents/openai.yaml)

Step 3: Agent Registry Registration

src/agents/registry.ts

Add an entry to the registry.

import { createNewAgentAgent } from "./newagent.js";

export const AGENT_REGISTRY: Record<ProductType, AgentDefinition> = {
  claude: createClaudeAgent(),
  gemini: createGeminiAgent(),
  codex: createCodexAgent(),
  opencode: createOpenCodeAgent(),
  newagent: createNewAgentAgent(),  // Add this
};

That's all — no changes to sync.ts / file-utils.ts are needed. The registry lookup automatically integrates into all sync operations.

Step 4: CLI Integration

src/cli/index.ts dynamically generates CLI options (--xxx-dir), description, and customDirs mapping from PRODUCT_TYPES and AGENT_REGISTRY. No changes needed.

Optionally, you can add usage examples for the new agent in the help examples section.

Step 5: Exports

src/agents/index.ts

Add re-export for the new agent.

export * from "./newagent.js";

src/index.ts re-exports src/agents/index.ts via export * from "./agents/index.js", so no additional changes needed there.

Step 6: Tests

Test Fixtures (tests/fixtures/)

• Place sample command files in tests/fixtures/newagent-commands/
• Place a sample skill in tests/fixtures/newagent-skills/test-skill/SKILL.md

New Test Files

Additions to Existing Tests

tests/utils/file-utils.test.ts and tests/agents/registry.test.ts use AGENT_REGISTRY, so simply adding to the registry will automatically be covered by existing tests.

Step 7: Documentation

CLAUDE.md

Update the following sections:

• Supported formats table (Commands / Skills)
• Placeholder conversion table
• Claude-specific fields section
• CLI option examples

README.md / README_ja.md

Update the following sections:

• Add agent name to the title description
• Features section
• Options table (--src / --dest description, add --newagent-dir option)
• Default File Locations (Commands / Skills)
• Add new column to Commands Format table
• Add new column to Content Placeholders table
• Skills Format description
• Add new column to Skill Metadata table
• Add link to Official Documents

File Change Checklist

New Files

Source:

• src/agents/newagent.ts — Agent class (body + command + skill parsing/conversion)

Tests:

• tests/parsers/newagent-command-parser.test.ts
• tests/parsers/newagent-skill-parser.test.ts
• tests/fixtures/newagent-commands/*.md (or .toml)
• tests/fixtures/newagent-skills/test-skill/SKILL.md

Modified Files

Source:

• src/types/intermediate.ts — Add to PRODUCT_TYPES
• src/types/command.ts — New command type (optional: existing types may suffice)
• src/types/skill.ts — New skill type (optional: existing types may suffice)
• src/agents/registry.ts — Add registry entry
• src/agents/index.ts — Add re-export

Tests:

• tests/utils/body-segment-utils.test.ts
• tests/converters/command-conversion.test.ts
• tests/converters/skill-conversion.test.ts
• tests/integration/cli.test.ts

Documentation:

• CLAUDE.md (If it exists)
• README.md
• README_ja.md

No Changes Needed (Automatically Handled by Registry Pattern)

• src/types/index.ts — Wildcard exports automatically re-export new types
• src/index.ts — Re-exports src/agents/index.ts via wildcard
• src/cli/index.ts — CLI options dynamically generated from PRODUCT_TYPES / AGENT_REGISTRY
• src/cli/sync.ts
• src/utils/file-utils.ts
• src/cli/options.ts
• tests/utils/file-utils.test.ts
• tests/agents/registry.test.ts
• tests/fixtures/fixtures.test.ts

Verification

pnpm verify && pnpm build