Carry producer cancellation separately from physical launch errors and diagnostic causes. Retain exact opaque reasons, LaunchSupport warnings, and rollback owners; consume the authored outcome without reclassifying failed launches from a later deadline.
Validation: focused client/provider/rollback and helper/MCP tests, check:fast, docs:check. Controlled native process ownership and Node bridge only; real Ghidra/JVM and Windows/Linux fault behavior unverified.
Refs #4517