Pre-existing silent-failure path: IsRunning decoded CP responses
regardless of HTTP status, so a CP 500 → empty body → State="" →
returned (false, nil). The sweeper couldn't distinguish "workspace
stopped" from "CP broken" and would leave a dead row in place.
## Fix
- Non-2xx → wrapped error, does NOT echo body (CP 5xx bodies may
contain echoed headers; leaking into logs would expose bearer)
- JSON decode error → wrapped error
- Transport error → now wrapped with "cp provisioner: status:"
prefix for easier log grepping
## Tests
+7 cases (5-status table + malformed JSON + existing transport).
IsRunning coverage 100%; overall cp_provisioner at 98%.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
e502003c74