Custom Emitters

Custom Emitters

The sidecar’s EmitterRegistry allows you to add custom translation targets. This lets AgentCTX translate CTX statements into any format — YAML, Terraform, Kubernetes manifests, or your own DSL.

How Emitters Work

An emitter is a pure function that converts a CTXStatement AST into a string:

interface Emitter {
  emit(ast: CTXStatement): string;
  emitBatch?(asts: CTXStatement[]): string;  // Optional batch support
}

Creating a Custom Emitter

Step 1: Define the Emitter

import type { CTXStatement } from '@agentctx/core';

const yamlEmitter = {
  emit(ast: CTXStatement): string {
    const lines = [
      `operation: ${ast.operator}`,
      `plane: ${ast.plane}`,
      `target: "${ast.target}"`,
    ];

    if (ast.filters.length > 0) {
      lines.push('filters:');
      for (const f of ast.filters) {
        lines.push(`  - type: ${f.type}`);
        lines.push(`    value: "${f.value}"`);
      }
    }

    if (ast.payload) {
      lines.push(`payload: "${ast.payload.raw}"`);
    }

    return lines.join('\n');
  }
};

Step 2: Register It

import { Sidecar, EmitterRegistry } from '@agentctx/core';

const registry = new EmitterRegistry();
registry.register('yaml', yamlEmitter);

const sidecar = new Sidecar(registry);

Step 3: Use It

const result = sidecar.translate(ast, 'yaml');
console.log(result.output);
// operation: ?
// plane: k
// target: "auth patterns"
// filters:
//   - type: tag
//     value: "code"
//   - type: limit
//     value: "3"

Built-In Emitters

Target	Output
human	English prose
surrealql	SurrealQL queries
sql	Standard SQL
rest	HTTP requests
graphql	GraphQL queries
mcp-jsonrpc	MCP JSON-RPC messages

Batch Support

For emitters that can optimize multi-statement output, implement emitBatch:

const csvEmitter = {
  emit(ast: CTXStatement): string {
    return `${ast.operator},${ast.plane},${ast.target}`;
  },
  emitBatch(asts: CTXStatement[]): string {
    return 'op,plane,target\n' +
      asts.map(a => `${a.operator},${a.plane},${a.target}`).join('\n');
  }
};

See Also

• Sidecar — how the sidecar works
• Formal Specification — the AST structure