Pair the static-content assertion with a behaviour test that runs the
postlude as a real shell script. Three scenarios exercise the three
branches inside the snippet: remote tip exists (track origin), no
remote (fresh local branch), and already on the target branch
(idempotency). This catches regressions where the snippet still parses
as bash but no longer does the right thing — wrong refspec, missing
-B, swallowed exit code, etc.
Strip the inline `git checkout -B` block from the Docker and Sprites
default prepare scripts. The kandev-managed postlude
(KandevBranchCheckoutPostlude) is appended unconditionally after every
user prepare script, so keeping the same logic inline made the default
and the postlude two sources of truth that could drift.
Profiles created in the UI snapshot the *then-current* DefaultPrepareScript
into their stored prepare_script field. Updates to the default — like
shipping the worktree-branch checkout block — never reach those older
profiles, so users keep landing the agent on the chosen base branch
(main) even though the env row carries a feature branch name.
Append a kandev-managed postlude to whatever prepare_script ran (custom
or default), wrapped in a subshell + `|| true` so it's idempotent and
never blocks agentctl from starting. The postlude prefers the remote tip
when origin already has the branch (resume after a destroyed sandbox),
falls back to checking out the existing local branch, and finally
creates one off the current HEAD.
Sprites needed the WorktreeProvider in resolvePrepareScript so the
postlude's `{{worktree.branch}}` actually expands; Docker already had
it.
The Docker e2e gains a regression case that explicitly stores an older
default-style script (clone, no checkout) and asserts the agent still
ends up on the feature branch — locking the contract in regardless of
which default the user happens to have stored.
When a sandbox is destroyed and we provision a fresh one for the same
task, the agent may have previously committed and pushed onto the
feature branch. The previous prepare scripts only ran `git checkout -b
{{worktree.branch}}` which would overwrite that progress with a fresh
branch off the chosen base.
Try `git fetch origin <feature>` first; on success, `git checkout -B`
against the remote tip so the agent picks up where it left off. Falls
back to a fresh local branch when origin has nothing.
Also add the same checkout block to the Sprites prepare script — it was
missing entirely, so every Sprites session was committing onto main.
José Almeida