`prompt_async` answers 204 as soon as OpenCode forks the run and reports
every later failure only on the session event stream, so an unusable
model, agent, or variant produced a session with no message while the
result still claimed `promptDispatched: true`.
Validate an explicitly requested model, agent, and variant against the
directory's own agent and provider lists before any session, worktree, or
goal is created, and confirm a new user message actually reached the
session before reporting the dispatch. A failed or empty lookup never
turns a valid selection into a rejection.
Bohdan Triapitsyn
9d3d5c0852