Multi-agent branching

nixify is worked on by several AI coding agents and one human operator, sometimes concurrently. The branching model exists to let that happen without agents corrupting each other’s work or the mainline — while keeping a strictly linear history.

Namespace

Branches are <owner>/<type>/<topic>:

• owner ∈ claude, gemini, copilot, codex — which agent (or the human) owns the branch.
• type ∈ feat, fix, refactor, docs, chore, ci, test.
• topic — the unit of work.

Protected refs (mainline, operator branches, and personal namespaces) are operator-only. Agents never commit, merge, or push there.

Parallel chains, one topic per root

Each agent works its own branches in its own git worktree, forked from the HEAD of the operator branch the work was authored on. One linear chain per topic; topics are never mixed across roots. Worktrees give each agent an isolated checkout sharing one object store, so parallel work doesn’t collide on a single working tree.

Agents do not touch another agent’s branches or worktrees. Cross-agent coordination happens through in-repo notes (handoff / session files at teardown), not by reaching into someone else’s checkout.

Integration is fast-forward only

Agents propose; the operator integrates. Merges into operator branches are fast-forward only, so the graph never grows a merge bubble and master stays a straight line. The only override is an explicit operator grant, and the rule is that the grant is quoted — its date, exact wording, and scope are recorded in the commit or merge body. (CLI merges that bypass local hooks make that quoting rule matter more, not less.)

Linear history, amend-at-source

A wrong commit is fixed where it was introduced — by amending that commit — rather than by stacking a forward-fix on top. The result is a history that reads as a sequence of correct, self-contained changes, which is far easier to bisect, review, and cherry-pick across the parallel chains.

Why this shape

Three properties fall out of it:

1. Safety — protected branches can only move through the operator, so an agent mistake is contained to its own branch.
2. Reviewability — linear, convention-named history makes “what changed and who changed it” obvious.
3. Parallelism — isolated worktrees plus per-topic chains let multiple agents make progress at once without a shared-state bottleneck.