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Constant

Constant is a local-first continuity tool for agent CLIs. Start a thread in Codex, carry it to Claude Code, then carry it back, without re-explaining the work.

Codex changes. Claude changes. The conversation stays constant.

Constant is early, alpha software. It works by reading and writing local runtime session files, so read the trust boundary before using it on sessions you care about.

Two surfaces

  • constant host runs one agent CLI at a time inside a native PTY and lets you switch the live runtime with a tmux-style prefix key. See Hosting a runtime.
  • constant carry does a headless carry into a target runtime's native session and prints the resume command. See Carrying a thread.

In host mode the child keeps its normal terminal UI, colors, keybindings, and resume behavior. Constant sits outside it, watches for a prefix key, and swaps the active runtime when you ask.

constant host codex
 
you talk to Codex
Ctrl-B c  ->  Claude Code continues the same thread
Ctrl-B x  ->  Codex continues it again

The switch is not a pasted summary. Constant reads the source runtime's local session, distills it to the conversation, writes a target-native session, and starts the target runtime with its own resume command. See How it works.

Runtime switching, not model switching

You are not swapping a model inside one app. You are swapping the whole runtime underneath one conversation. The transcript is the constant; the runtime, and its character, is what changes. The divergence between Codex and Claude on the same thread is the point, not a bug.

What it is not

  • Not a multi-agent dashboard, model router, or API proxy.
  • Not a terminal multiplexer. It hosts one runtime at a time and passes output through untouched.
  • Not a claim of shared native memory between providers. See What carries.

Supported runtimes

  • Codex CLI, validated against 0.137.x
  • Claude Code, validated against 2.1.x

Planned: OpenCode, Aider, Gemini CLI.

Next: Installation.

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How it works