Live Desktop repro: the fixture model called browser_vault_unlock and got
unlock_unavailable although the renderer was interactive. tool_executor runs
handlers on a propagated worker thread; thread_context only copied the
approval and sudo thread-local callbacks, so the unlock prompt registered by
_wire_callbacks was invisible there and can_prompt_here() said nobody could
answer. The callback table in thread_context now lists every per-thread
prompt (approval, sudo, vault unlock) so a new one cannot silently drop off
worker threads again. After the fix the same turn shows the masked card and
completes.
vault.sources / `hermes vault sources` report a manager as installed when
its configured binary_path exists, not only when it is on PATH.
Worker threads that dispatch Hermes tools started with an empty contextvars.Context and no thread-local approval/sudo callbacks. Add tools/thread_context.propagate_context_to_thread factoring that capture/install/clear lifecycle (mirrors the GHSA-qg5c-hvr5-hjgr pattern), and refactor agent/tool_executor onto it so the security-critical logic lives in one audited place. Update the contextvar-propagation source guard for the new call shape.
Refs #33057
Teknium