Mellions Coxen
Turn frontier coding agents into engineers who stay on the job.
Mellions Coxen is an engineering responsibility and reliability layer for frontier coding agents: continuity, ownership, falsification, coordination, and disciplined completion.
Integrated with the engineering tools you already use
Claude Code
Codex
GitHub
Stop managing every prompt.
A capable coding agent can still leave you choosing every next task, re-explaining context, approving obvious follow-up work, and checking whether “done” actually means done. Mellions Coxen reduces that management load.
Own the whole responsibility
Established defects inside the active code path are carried through root cause, implementation, and verification instead of handed back as another approval request.
Try to prove the answer wrong
Passing tests are evidence, not automatic proof. Consequential conclusions are challenged with mutations, comparisons, and checks that can genuinely fail.
Continue across interruptions
Assignments and current repository state preserve the responsibility across restarts, compaction, handoff, and parallel engineering lanes.
Frontier-model judgment. Deterministic mechanisms where they earn their keep.
The coding runtime keeps its native reasoning, tools, permissions, worktrees, subagents, sandboxing, and model choice. Mellions supplies the durable engineering layer around that capability.
01
Establish reality
Read the running system, source, history, tracker, and governing contracts before treating the task description as truth.
02
Carry the work
Proceed autonomously on ordinary engineering decisions and escalate only the judgments that genuinely belong to a person.
03
Falsify completion
Verify the original obligation, neutralize important fixes, and make sure the claimed proof turns red for the intended reason.
04
Leave durable state
Keep the issue, pull request, assignment, and handoff aligned so another session can continue from evidence rather than replaying a conversation.
Real integrations, precisely described.
The engineering model is portable, but automatic lifecycle integration is a runtime-specific support claim.
Runtime integration
Claude Code
First-class and production-used
Native plugin, Skills, slash commands, lifecycle and awareness hooks, recovery, renewal, and unattended runner support.
See the integration matrixRuntime integration
Codex
Implemented and interactive
Plugin, Skills, commands, and hook manifest are present. Codex must explicitly trust the hooks; the unattended runner is currently Claude-only.
See the integration matrixProject surface
GitHub
Source, coordination, and evidence
The repository carries source, documentation, issues, pull requests, releases, contribution guidance, and cross-host work claims.
See the integration matrixStronger completion, with evidence you can inspect.
Mellions Coxen is developed through production use, controlled same-model comparisons, and deterministic replay. Its public record separates observed behavior from retrospective estimates instead of presenting one case study as a universal coding benchmark.
- Defect ownership
- Without Mellions Coxen
Finds another real defect, then asks whether to fix it.
- With Mellions Coxen
Establishes whether the defect belongs to the active responsibility and owns it when it does.
- Verification
- Without Mellions Coxen
Treats a green test suite as the stopping point.
- With Mellions Coxen
Actively tries to disprove consequential conclusions.
- Continuity
- Without Mellions Coxen
Leaves most session state inside the conversation.
- With Mellions Coxen
Carries durable responsibility across interruption and handoff.
- Coordination
- Without Mellions Coxen
Lets parallel agents unknowingly duplicate work.
- With Mellions Coxen
Makes active responsibility and overlapping work visible.
Install the CLI and plugin together.
After checkout, one make install command builds the Go CLI and registers the Mellions plugin with supported coding runtimes already present on the machine.
Supported today: source installation
A one-click installer or hosted marketplace install is not published today. Requires Go 1.26.1 or newer, Git, an authenticated GitHub CLI, Claude Code and/or Codex, and macOS or Linux.
Read the complete installation guidegit clone https://github.com/LetA-Tech/mellions-coxen.git
cd mellions-coxen
make install
mellions config init
mellions doctorOpen source means the product story is inspectable.
Read the implementation, reproduce the evidence, report failures, and contribute a stronger mechanism when the evidence supports it.
Documentation
Architecture, CLI, installation, integrations, and operating playbook.
Releases
Versioned source, release notes, and downloadable artifacts.
Issues
Report reproducible failures and follow the public engineering record.
Contribute
Challenge the claims, improve the mechanisms, and submit evidence-backed changes.