Branch Executor.Prompt on lifecycle.Manager.IsPassthroughSession so that
follow-up prompts from any UI surface (the kanban Preview screen, mobile
session view, etc.) reach the running CLI agent via PTY stdin instead of
silently falling through to the ACP path. WritePassthroughStdin failures
propagate so Service.handlePromptError reverts session state and surfaces
the error; MarkPassthroughRunning failures are non-fatal because the data
is already in the PTY.
Closes the backend half of #989; the Preview-side UI compose box ships
in a follow-up commit.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Kandev Agent
85edb4546b