Decouple observer stream identity from machine link identity: observers resolve by handle only (X-Solstone-Observer header, else Authorization Bearer), never by link fingerprint. Removes the dead fingerprint→observer resolution path + the observer-revoke→machine-deauth coupling. Machine trust (PL mTLS admission, :5015 loopback, authorized-clients ledger) unchanged. Peer/journal-source identity unchanged (delineated in docs). Unblocks satellite observers shipping over the link (with the client X-Solstone-Observer change). CSO-approved (req_pzv7ljbo).