Claude Code ↔ Codex coordination bridge

Status: Experimental · Pre-1.0 · under active development · not production-certified. This is the first experimental open-source release. APIs, MCP tool shapes, persisted state, and workflows may change without notice and without a migration path. Use it only in trusted local repositories on work you can review.

A local, repository-scoped coordination bridge that lets Claude Code and Codex work in the same checkout without stepping on each other. It gives both agents one shared control plane for tasks, ownership, write-scope leases, artifacts, verification evidence, recovery, and runtime telemetry, exposed to each client as a native project-scoped MCP server.

The bridge is a coordination layer. It does not choose the better model, split work automatically, or merge code for you.

Table of contents

• What problem it solves

• Project status and honest limits

• Architecture

• Requirements

• Installation

• Quick start

• Project-scoped MCP configuration

• The using-bridge skill

• Bounded delegation

• Ownership and leases

• Recovery

• Telemetry

• Troubleshooting

• Security and privacy

• Contributing

• Release policy

• Documentation map

Related MCP server: asynkor

What problem it solves

Running two coding agents in one repository creates coordination problems that neither client solves on its own. The bridge addresses them with explicit mechanisms:

Project status and honest limits

Demonstrated on this implementation

• real Claude Code → bridge → Codex delegation;

• real Codex → bridge → Claude Code delegation;

• native project-scoped MCP integration for both clients;

• task ownership and time-bounded write-scope leases;

• structured deliverables with real verification evidence;

• persisted Claude and Codex execution handles;

• same-task, same-runtime-session recovery after interruption;

• runtime-reported token telemetry for both workers;

• startup-bound caller identity and anti-spoofing checks;

• server-side delegation allow/deny;

• parent/depth validation and ancestor-loop protection;

• deterministic regression coverage (npm test).

Explicitly not established

• superiority over single-agent workflows;

• token savings or economic efficiency of any kind;

• production security or production readiness;

• large-scale, multi-user, or long-horizon reliability;

• benchmark advantage over either agent alone;

• optimal or automatic routing of work between models.

Controlled Claude-alone versus Codex-alone versus bridged benchmarking is planned but has not been completed. This repository makes no performance, cost, or security claim beyond what its committed tests and redacted evidence show.

Architecture

flowchart LR
  Claude[Claude Code] -->|project .mcp.json / stdio| ClaudeBridge[Native bridge<br/>caller=claude]
  Codex[Codex] -->|project .codex/config.toml / stdio| CodexBridge[Native bridge<br/>caller=codex]
  ClaudeBridge --> Core[Agent-neutral MCP core]
  CodexBridge --> Core
  Core --> Control[Task and lease control plane]
  Control --> SQLite[(Local .bridge/bridge.db)]
  ClaudeBridge --> ClaudeAdapter[Claude adapter]
  CodexBridge --> CodexAdapter[Codex adapter]
  ClaudeAdapter --> ClaudeRuntime[Claude Code CLI]
  CodexAdapter --> CodexRuntime[Codex App Server or MCP client]

Each client launches the same composition root, scripts/native-bridge-mcp.mjs, with a different startup-bound caller. The two processes coordinate through one repository-local SQLite database. The neutral dependency direction is:

@bridge/protocol
        ↓
@bridge/control-plane
        ↓
@bridge/mcp-server-core
        ↓
Claude and Codex adapters

Details: docs/architecture.md. Normative wire contract: docs/PROTOCOL.md.

Requirements

• Node.js >= 22.13.0 — required, because node:sqlite is used without an experimental CLI flag. The engines field in package.json enforces the same floor.

• npm (workspaces) and Git.

• Claude Code and Codex installed and authenticated, for real delegations.

• A trusted local checkout. The bridge launches coding runtimes that can read, write, and run shell commands.

Installation

The supported workflow is deterministic and uses the committed lockfile:

npm ci          # deterministic install from package-lock.json
npm run build   # tsc --build; required before a client opens the bridge
npm test        # vitest run; the deterministic regression suite

npm ci (not npm install) is what makes the dependency tree reproducible. The native launcher imports compiled workspace packages, so npm run build must succeed before you open the bridge from a client. Run the suite yourself rather than trusting a recorded test count in prose.

Optional checks: npm run typecheck forces a clean type build, and npm run links:check inspects workspace package links (use npm run links:fix only when it reports a break).

More detail: docs/installation.md.

Quick start

1. Clone the repository and cd into it.

2. Run npm ci && npm run build && npm test.

3. Verify MCP discovery from the repository root:

   claude mcp list     # expect a "bridge" server, caller=claude
   codex mcp list      # expect a "bridge" server, caller=codex

   On Windows without a global Codex on PATH, use .\node_modules\.bin\codex.cmd mcp list.

4. Launch either client from the repository root and approve the project-scoped MCP server when prompted. Inside Claude Code, /mcp shows the active connections.

5. Ask the client to use the using-bridge skill for one bounded delegation, then read the two worked examples in Bounded delegation.

Project-scoped MCP configuration

Both configuration files are committed, repository-relative, and contain no credentials. Neither creates a global MCP registration.

Claude Code — .mcp.json:

{
  "mcpServers": {
    "bridge": {
      "type": "stdio",
      "command": "node",
      "args": [
        "${CLAUDE_PROJECT_DIR:-.}/scripts/native-bridge-mcp.mjs",
        "--caller", "claude",
        "--delegation", "allow",
        "--workspace", "${CLAUDE_PROJECT_DIR:-.}"
      ],
      "env": {}
    }
  }
}

Codex — .codex/config.toml:

[mcp_servers.bridge]
command = "node"
args = ["scripts/native-bridge-mcp.mjs", "--caller", "codex", "--delegation", "allow"]
cwd = "."
startup_timeout_sec = 30
tool_timeout_sec = 1800

Caller identity is bound when the server process starts. A tool call that contradicts the bound caller is rejected; an omitted caller field resolves to it. Starting the launcher with --delegation deny keeps inspection and telemetry available while refusing bridge_delegate server-side.

Review both files before granting project trust, and never hand-edit client trust state.

The using-bridge skill

The same bounded-coordination skill is committed for both native clients:

• Claude Code: .claude/skills/using-bridge/SKILL.md

• Codex: .codex/skills/using-bridge/SKILL.md

Open a client from this repository and ask it to use the using-bridge skill when a bounded delegation, independent review, recovery, or telemetry lookup is genuinely useful. The skill keeps the current client responsible for the user's request, defaults to one child with zero retries, and explicitly does not treat "use both models" as a reason to delegate. Only these shared skill files are versioned; other client-local state stays ignored.

Bounded delegation

A delegation is one bounded request and one structured answer — never an open conversation between agents. Every DelegationRequest carries a deadline, the root run_id, the parent task_id, and a depth. Inputs are artifact IDs, not transcripts.

Example: Codex → Claude

Ask Codex, running from the repository root:

Use the bridge MCP. Confirm caller=codex, then create and claim one depth-0 root task for "review the lease-expiry logic". Delegate exactly one depth-1 child to Claude with scope (no-write)/**, a 10-minute deadline, max_attempts: 0, and the verification criterion "cites concrete file:line evidence". Consume the child's structured deliverable, verify it yourself, then submit the root deliverable. Report lineage, final states, and worker telemetry without exposing execution handles.

Example: Claude → Codex

Ask Claude Code, running from the repository root:

Use the bridge MCP. Confirm caller=claude, then create and claim one depth-0 root task for "add a regression test for expired-lease renewal". Delegate exactly one depth-1 child to Codex with write scope shared/control-plane/src/**, a 15-minute deadline, max_attempts: 0, and the verification criterion "npm test passes". Consume the child's structured deliverable, verify it yourself, then submit the root deliverable. Report lineage, final states, and worker telemetry without exposing execution handles.

In both directions the manager stays responsible for the user's request, bridge_server_info is confirmed once per native session, and bridge_snapshot is used only when concurrent ownership is plausible. If the target runtime is unavailable, report the runtime failure — do not create a replacement child task.

Claude worker profile

The bridge runtime, not the manager and not the skill, owns Claude model selection. Every bridge-created Claude worker — fresh or resumed — is launched through Claude Code's supported interface with --model opus --effort high. A delegation payload cannot override that profile. If Claude Code reports an actual non-Opus model, the attempt fails with RUNTIME_PROFILE_MISMATCH; if it reports no model at all, telemetry keeps the actual model null rather than inventing one.

Claude turn ceilings are finite: minimum 1, conservative default 12, maximum 64, with 32 as the recommended starting value for a bounded repository audit. Set TaskSpec.max_turns only when the default is genuinely too small; the value persists with the task and is reused on strict recovery.

Full workflow: docs/usage.md.

Ownership and leases

• Exactly one agent owns a task. Claiming a task is not permission to write.

• Before editing files, the owner acquires a lease over repo-relative glob patterns (*, **, ?). An overlapping live lease held by a different agent is refused with SCOPE_CONFLICT.

• Overlap detection is deliberately conservative: when two patterns cannot be proven disjoint, the bridge reports a conflict. A false conflict costs a retry; a false clearance costs corrupted files.

• Leases are time-bounded and expire lazily against an injected clock, so a crashed agent cannot deadlock the repository and tests stay deterministic. Renewing a lapsed lease is refused, because the scope may already belong to someone else.

• A read-only task declares (no-write)/** and returns changed_scope: [].

These are coordination contracts enforced by the control plane. They are not an operating-system sandbox: a delegated runtime with shell access can still write outside its declared scope, which is why the bridge is for trusted local repositories only.

Recovery

Adapters persist an opaque runtime handle (a Claude session id, a Codex thread id) as soon as the session exists — not on completion, because the only time anyone needs it is when the run died. bridge_resume_task takes the durable task ID, derives owner, lineage, scope, and handle from SQLite, rejects live or conflicting leases, takes a fresh lease, creates the adjacent attempt, and requires strict resume of that exact runtime session. It never accepts a caller-supplied handle and never opens a replacement task or thread.

See docs/recovery.md.

Telemetry

The bridge records one normalized final record per attempt: worker identity, lineage, timing, token, cache, cost, turn, artifact, and termination fields — but only when the runtime reports them authoritatively. Unknown values stay null; missing manager tokens are never estimated, and cached token counts are subdimensions of input, not extra tokens to add again. Raw prompts, responses, authentication data, and execution handles are outside the durable telemetry schema.

Runtime-reported cost is not confirmed billing. See docs/telemetry.md.

Troubleshooting

Common first stops: the bridge is not listed by claude mcp list / codex mcp list, the server starts but tools fail, SCOPE_CONFLICT on every lease, a task is stranded after an interrupted run, or telemetry fields are null. Each case, with the exact check to run, is in docs/troubleshooting.md.

Security and privacy

The bridge is local-first, but it launches powerful coding runtimes. Leases stop cooperating agents from claiming overlapping scopes; they do not confine shell commands at the operating system level, and nothing here has been audited for production use.

Never commit or publish:

• .bridge/ SQLite databases or WAL/SHM sidecars;

• Claude or Codex trust state;

• raw handles, prompts, transcripts, runtime frames, or credentials;

• logs, temporary task directories, node_modules, coverage, or build output.

Review git status, staged paths, and secret-scan results before any push. To report a suspected vulnerability, see docs/security.md.

Contributing

Contributions are welcome, with small, local, evidence-backed changes preferred. Read CONTRIBUTING.md before opening a pull request; it covers the local gates, the evidence standard, the claim discipline this project applies to itself, and repository hygiene rules.

Release policy

Pre-1.0 and experimental: no compatibility guarantee, no support commitment, no security certification. Breaking changes may land in any release and are recorded in CHANGELOG.md. The stability rules, versioning scheme, and what would have to be true before a 1.0 are in docs/release-policy.md.

The project is licensed under the MIT License. Package manifests remain private because this release publishes source on GitHub, not packages to the npm registry.

Documentation map

• Architecture — packages, data flow, invariants

• Installation — requirements, deterministic setup, project MCP config

• Usage — manager workflow, worked examples, writing tasks

• Telemetry — recorded fields, sources, privacy boundary

• Recovery — persisted handles, strict same-task resume

• Troubleshooting — symptoms, checks, and fixes

• Security and privacy — trust boundary, controls, disclosure

• Release policy — versioning and stability expectations

• Roadmap — current phase and what is out of scope

• Normative protocol — lifecycle, tools, error codes

• Bridge skill context pack — background on the skill design

• Contributing · Changelog