A parent-side ctx cancel timeout previously bounded only the
remote `_cancel_task` ack. Complete-frame `send_all()` shielding
could hold request publication forever when a peer stopped reading.
Compute one absolute deadline and pass it through `._run_from_ns()`
so transport publication and the ack wait consume the same timeout
budget. Add a mock-clock regression which stalls the private RPC
under a nested shield and proves the transaction returns on time.
Review: PR #481 (goodboy)
https://github.com/goodboy/tractor/pull/481#pullrequestreview-5012942328
Prompt-IO: ai/prompt-io/opencode/20260824T222033Z_ce38cb6f_prompt_io.md
(this patch was generated in some part by `opencode` using `gpt-5.6-sol` (`openai`))
Gud Boi