Sixteen claude.* handlers reported ok with an `error` field buried in
the payload — `clide claude.agent.set-permission-mode bogus` exited 0,
so scripts could not detect failure, drifting from the D-6 exit-code
contract every other subsystem honors. Missing/invalid args are now
userError, missing sessions notFound, a missing orchestrator
toolError, and a failed task reassign no longer reports ok:false as a
success. No UI consumer read the old payloads. Table-driven test
walks every failure path asserting non-zero codes.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>