Wire v2: end-to-end deadlines and cancellation by request ID #173

Problem

Queue timeout and cancellation need one contract spanning admission through computation, including the durable write boundary.

Evidence

Source: 5c1f313379a5cb2995a43a66ddba0b5cc9798b7f (inspected 2026-10-03). These are source findings; the acceptance scenarios below still need implementation and execution.

• src/protocol/handler.rs:2280: Admission currently waits for the query semaphore.
• src/protocol/handler.rs:4135: Session execution has its own admission path.

Acceptance criteria

• Carry one deadline across admission, queueing and execution; cancellation by request ID reaches queued and running work.
• A timed-out queued operation never starts later. Running queries release resources promptly.
• Document that durable commit cannot be cancelled midway; report committed/unknown outcomes explicitly for safe retry.
• Test cancellation on both sides of the transaction boundary and preserve cheap-query/delta performance through Performance: baseline and mandatory pre-PR regression pipeline #163.

Delivery

Plan item: W03. R2 - Atomic programs + wire protocol.

Dependencies / related work: #172, #170.

Contributes to #132; completing this slice alone does not close the broader issue.