cogem-core

Run OpenAI Codex on your own Gemini key. Point the Codex harness at a BYOK Gemini model through a pure-Rust bridge — keep the full Codex agent (plan, approval, tools, apply_patch via shell) and Gemini’s native grounding, code execution, and thinking, together.

The bridge binary is fetched and supervised automatically — no Rust toolchain, no CG_DIR, no setup.

Runs on the Bun runtime (it uses bun:sqlite + the bun globals). A plain Node process can’t load it.

Install

bun add cogem-core

Quickstart

import { createCg } from 'cogem-core'

const cg = await createCg({ apiKey: process.env.GEMINI_API_KEY })
try {
  const result = await cg.run(
    'Add a multiply(a, b) function to math.py and edit the file.'
  )
  console.log(result.finalResponse)
} finally {
  cg.stop()
}

createCg downloads the prebuilt bridge once (cached under ~/.cache/cg), supervises it, opens a Codex session on Gemini, and gives you run(task, { workingDirectory, outputSchema, approvalPolicy }). Only apiKey is required; model defaults to gemini-3.5-flash, port to 4011.

Structured output

const r = await cg.run('Describe a person named Alice who is 30.', {
  outputSchema: {
    type: 'object',
    properties: { name: { type: 'string' }, age: { type: 'integer' } },
    required: ['name', 'age']
  }
})
// r.finalResponse is schema-conformant JSON, even though the prompt asked for prose.

Building blocks

createCg is the one-call path; the primitives are exported for advanced use:

• BridgeSupervisor — resolve + supervise the bridge sidecar (override the binary with binaryPath, or run a local build with cgDir).
• CodexRuntime — the typed SDK path (run / runResilient / stream / structured output).
• AppServerSession — the full app-server surface (goals / fork / steer / interrupt / resume / approvals).
• SecretStore — store the BYOK key in the OS keychain. ThreadStore — local thread persistence.
• runResilient — deadline + retry + backoff for a turn under load.

Architecture, decisions, and the per-capability can-fail tests live in the cg-doc repo.