codex-reasonix-mcp

codex-reasonix-mcp is a security-first MCP bridge that lets Codex supervise Reasonix as an implementation worker. Codex owns the contract, review, and final commit decision. Reasonix works in an isolated Git worktree through ACP Goal mode. The bridge never pushes, merges, or changes the caller's main worktree.

This repository is generic to Git repositories. It contains no Akademi-specific configuration, LLM router, or Codex source modification.

Release status

The current package version is the stable 0.1.1 release. Official Reasonix v1.19.0 includes the ACP v1 supervisor and status capabilities required by the bridge. Runtime capability checks remain authoritative, and incompatible binaries fail closed before any model prompt is sent.

Related MCP server: MiMo Bridge MCP

Requirements

• Node.js 22 or newer

• pnpm 10 for source development

• Git 2.36 or newer (worktrees plus git hook run)

• Linux, macOS, or Windows through WSL; native Windows is rejected

• Reasonix v1.19.0 or a compatible newer build with the required ACP v1 supervisor and status capabilities

• Bubblewrap on Linux/WSL or Seatbelt on macOS

• A configured Reasonix provider exposing deepseek-v4-flash

Reasonix, provider credentials, and provider billing remain user-managed. This package neither downloads nor bundles Reasonix.

Install for Codex

Pin the exact bridge version when registering the MCP server:

codex mcp add reasonix-worker -- npx -y codex-reasonix-mcp@0.1.1

For development against a locally built Reasonix checkout:

codex mcp add reasonix-worker \
  --env REASONIX_BIN=/absolute/path/to/reasonix \
  -- npx -y codex-reasonix-mcp@0.1.1

Run the non-model diagnostic before delegating work:

npx -y codex-reasonix-mcp@0.1.1 doctor

doctor checks Node, Git, platform/WSL, the Reasonix binary and supervisor flags, ACP extension compatibility, OS sandbox availability, state permissions, network posture, the required model selector, and the effective session sandbox. It creates and closes an ACP diagnostic session but never sends a model prompt.

MCP surface

The server is named reasonix_worker and exposes exactly three tools:

• reasonix_delegate validates an immutable TaskContractV1, creates the worker branch/worktree/session, and returns while provisioning continues.

• reasonix_control steers, answers an interaction, cancels, finalizes, or closes a task. At most two post-review repair rounds are accepted.

• reasonix_inspect returns bounded status, evidence, interactions, events, and optional paginated diffs.

Codex calls reasonix_delegate only after the user explicitly requests or approves Reasonix implementation. Once approved, Codex does not substitute native subagents for that contracted work. Native Codex subagents remain the right fit for bounded parallel exploration, tests, triage, or summaries that do not require the Reasonix task lifecycle.

reasonix_delegate and finalization require Codex's codex/sandbox-state-meta. A writable repository path is derived only from that metadata; no model-provided repository path is accepted.

Safe lifecycle

1. Codex creates a contract with explicit write and forbidden scopes.

2. The bridge rejects a dirty source worktree, creates reasonix/<task-id>, and places the worker worktree below its private state directory.

3. Reasonix runs Delivery + Goal with planner disabled, scoped writes, sandboxed bash, and network off by default.

4. Codex inspects bounded evidence and may request at most two repair rounds.

5. finalize reruns all verification, rechecks scope/size/secrets, stages explicit files, runs commit hooks against a disposable index, and advances the worker ref only when the resulting tree is byte-for-byte the reviewed tree.

6. The branch, worktree, contract, and evidence are retained. Nothing is pushed, merged, cherry-picked, or deleted automatically.

See architecture, task contracts, configuration, security, and troubleshooting.

Develop

corepack enable
pnpm install --frozen-lockfile
pnpm check
pnpm audit --audit-level high

CI runs the same gates on Node 22/24 Linux and Node 22 macOS. npm releases use GitHub OIDC trusted publishing with provenance and no long-lived npm token; prerelease versions publish under the next dist-tag. See CONTRIBUTING.md for the release gates.

The offline end-to-end test uses a fake ACP Reasonix agent and performs no live provider calls or external mutations. A live DeepSeek smoke test is intentionally not automated and requires explicit credential and cost authorization.

Community

• Read CONTRIBUTING.md before proposing a change.

• Use the structured bug report or feature request forms for public work.

• Follow the Code of Conduct in all project spaces.

• Report vulnerabilities privately through GitHub Security Advisories, as described in SECURITY.md.

License

MIT. See LICENSE.