feat: add madtea switch and madt_switch to move to an existing branch #894

Merged

hexajon merged 17 commits from issue-867-switch-on-main into main

2026-10-24 00:42:15 +00:00

hexajon commented

2026-10-24 00:42:11 +00:00

Owner

Summary

madtea had no surface that moves HEAD to a branch that already exists, so a caller that drives git through madtea fell back to raw git switch to return to the default branch. This adds madtea switch <branch> and madt_switch.

It moves HEAD to an existing local branch, the default branch included, and reports the branch and the new short HEAD sha.
It never creates a branch. A name that only a remote-tracking ref holds, a tag, or a commit is refused with git's own words, and the refusal names the exact madt_branch_create or madtea branch -b call.
Uncommitted changes that do not conflict carry onto the target branch, as in git. A switch that would overwrite a change refuses with git's message.
A switch to the branch that is already checked out succeeds and says that HEAD did not move.
A foreign primary checkout is refused, and so is a dirty linked worktree of a foreign repo. The decision records for foreign repos now name the switch.
A branch that another worktree holds is refused with steps that never act on that worktree.

Closes #867

## Summary madtea had no surface that moves HEAD to a branch that already exists, so a caller that drives git through madtea fell back to raw `git switch` to return to the default branch. This adds `madtea switch <branch>` and `madt_switch`. - It moves HEAD to an existing local branch, the default branch included, and reports the branch and the new short HEAD sha. - It never creates a branch. A name that only a remote-tracking ref holds, a tag, or a commit is refused with git's own words, and the refusal names the exact `madt_branch_create` or `madtea branch -b` call. - Uncommitted changes that do not conflict carry onto the target branch, as in git. A switch that would overwrite a change refuses with git's message. - A switch to the branch that is already checked out succeeds and says that HEAD did not move. - A foreign primary checkout is refused, and so is a dirty linked worktree of a foreign repo. The decision records for foreign repos now name the switch. - A branch that another worktree holds is refused with steps that never act on that worktree. Closes #867

hexajon added 17 commits

2026-10-24 00:42:11 +00:00

test: pin madtea switch and madt_switch behaviour (red) 23f47ed5b8

feat: add madtea switch and madt_switch to move to an existing branch 0a10001c2b

fix: address review findings on madtea switch 49078ed07e

docs: name madt_switch in the foreign-primary and fail-closed records d6e26e715e

test: pin the round-2 switch decisions (red) 640e937f92

feat: round-2 switch decisions (git wording, unchanged no-op, held-branch steps) bf944959c3

fix: fit the madt_switch pointer in the server instructions budget f0751d7a68

fix: address round-2 review findings on madtea switch 64c685bc3d

fix: restore the approved short madt_switch pointer in the server instructions b0dac5b5ff

test: pin the git facts behind the switch decisions with real git 4b08e7b9a1