The thinnest harness that can rewrite itself.
powershell. installs inside wsl, so run wsl --install first if you have none.
malleable
Most agents extend through a plugin API — a fixed set of hooks the harness author chose to expose. micro·cc ships as plain, readable Python instead. No compiled binary, no build step: the running process is the files on disk.
Ask for a change in words and it edits its own source, restarts into it, and comes back changed. That works on any install — a dev checkout, or a pip, pipx, brew or uv install on macOS, Linux or WSL — and every fresh install is told in its own system prompt that it can do this.
Editing the package is also the fragile way: the next update replaces the file. So what you
add for yourself lives outside it — a mod in ~/.micro-cc, where pip
never installs. One file, one register(on), and your handlers ride
the same event bus the built-in interface runs on: commands, keys, glyphs, and every component
on screen. The built-in behaviour is still underneath, one
nxt(e) away, so you decide whether to wrap it or replace it.
orchestration
A subagent is another full instance of the same harness: its own project directory, its own durable conversation, the same tools and skills. One shell call starts it, and it announces itself to the session that spawned it the instant it comes up — no manifest, no registration API.
Status is read from the child's own transcript, and a checkpoint arrives as a real new turn rather than a poll. Sessions message each other directly, and a paused child resumes its exact history.
the whole of it
A harness is a loop: the model asks, the machine answers, around again. micro·cc is that loop in plain Python with nothing sealed around it, so the file it runs from is a file the model can open and edit.
When it does, micro·cc waits for the turn to end, re-executes in place under the same process id and rebuilds the conversation from disk. If the new code will not boot, a small supervisor reinstalls the published release.