Hidden resume-message runtime_kind metadata value for a bash-completion
self-resume (issue #84 Phase 2b). Shared by the producer (the self-resume
task that appends the resume message) and the consumer (the suspend-
finalization discriminant arm that preserves it), so a typo in one cannot
desync from the other and silently drop the resume trigger.
Re-exported so peers that already use crate::runtime::config::{BashResumeHook, …}
(the runtime/spawn threading) can name the completion sink the same way,
rather than reaching into bamboo_agent_core separately.
Loop-facing sink invoked exactly once when a background Bash shell completes.
Late-bound hook that arranges a self-resume for a session suspended waiting
on background Bash shells (issue #84 Phase 2b). Injected per-request on
AgentLoopConfig exactly like GuardianSpawner; the implementation
lives in the session-app layer (on the completion coordinator) where the
resume port (crate::session_app::resume::ResumeExecutionPort) is
reachable.