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.
José Almeida
8e3faf5699