Mechanism to code

Part of core components. The six mechanisms, by where each lives in the tree.

mechanism	core-side implementation	provider-side twin
Identity is an Ed25519 keypair	identity.py (verification, payload builders, FunduqIdentity); challenges and roster rules in core.py's _Roster	funduq_provider_sdk.identity (keypair, signers, payload builders)
Actor chain	identity.py (verify_chain, chain builders)	funduq_provider_sdk (sign_hop, verify_chain)
Runs and cancels are requests	broker.py (three-valued offer, cancel relay, observed outcomes)	FunduqLink.offer / Refusal in funduq_provider_sdk
Provider quality counters	live_roster.py counters; snapshots via RunBroker.quality / KyokRelay.quality	— (observed, not reported by providers)
Keep your own key	kyok.py (bindings, tokens, relay) + protocols/kyok.py (call authorization, relay envelope)	funduq_provider_sdk.llm (link, handler, CompletionRefused)
Responsibility chains	repo.py (head_key on threads and runs, ThreadMembershipRequired), doors.py (verify_caller and its presenter check, authorize_cancel, the resolution check in open_run), identity.py (verify_resolution, verify_cancel, verify_delegation)	funduq_provider_sdk.identity (sign_resolution, sign_cancel, sign_delegation, extend_chain)

Vouchers are the row's one unimplemented part — translating a key to a person is a disclosure only a deployment's own IdP can make, and responsibility chains says so. Everything else on that page — a thread bound to a head at birth, answering and stopping needing a signature from that head, break and extend as behaviours rather than fields — is code with tests against it. The row said "not implemented — design record only" while 37 tests exercised it, which is the drift this table exists to prevent.

The byte-level agreement between the two columns is contract-vectors.json; neither column imports the other.