File Location ~/.config/opencode/plugin/codex-proxy-plugin.ts

codex-proxy-plugin.ts

import type { Plugin } from '@opencode-ai/plugin';

/**
 * Custom fetch wrapper that removes max_output_tokens and max_completion_tokens
 * from the request body before sending to the API.
 *
 * @param input - The request URL or Request object
 * @param init - Optional request init options
 * @returns The fetch response
 */
async function codexFetch(input: Request | string | URL, init?: RequestInit): Promise<Response> {
  if (!init?.body || typeof init.body !== 'string') {
    return globalThis.fetch(input, init);
  }

  try {
    const originalBody = JSON.parse(init.body);

    // Remove token limit parameters that may cause issues
    delete originalBody.max_output_tokens;
    delete originalBody.max_completion_tokens;

    const modifiedInit: RequestInit = {
      ...init,
      body: JSON.stringify(originalBody),
    };

    return globalThis.fetch(input, modifiedInit);
  } catch {
    // If JSON parsing fails, proceed with original request
    return globalThis.fetch(input, init);
  }
}

/**
 * Codex Proxy Plugin
 *
 * Intercepts requests to OpenCode providers and applies custom fetch handling
 * to modify request parameters before they are sent to the API.
 */
export const CodexProxyPlugin: Plugin = async () => {
  return {
    config: async (input) => {
      // const provider = input.provider?.['openai-duckcoding'];
      const provider = input.provider?.['openai'];
      if (provider) {
        if (!provider.options) {
          provider.options = {};
        }
        provider.options.fetch = codexFetch;
      }
    },
  };
};

export default CodexProxyPlugin;

"openai": {
      "options": {
        "baseURL": "https://jp.duckcoding.com/v1"
      },
      "models": {
        "gpt-5.2": {
          "options": {
            "include": [
              "reasoning.encrypted_content"
            ],
            "store": false,
            "reasoningEffort": "high",
            "textVerbosity": "high",
            "reasoningSummary": "auto"
          }
        }
      }
    }