Ordered labelled sources tried until one returns bytes. A miss or error
moves to the next source; the set errors only when every source errored.
The error table is locked only to read or write, never across a fetch.
Checkpoint-relative Litecoin light client. Does not validate scripts, UTXOs
or MWEB consensus. Opening it does not start network connections; the first
sync attempt does. An application start before the configured anchor is an
explicit error, never silently replaced with the anchor’s height.
Optional local Litecoin Core: it may start, stop, restart or hang at any
time. Holds only the URL and cookie path; every lookup and probe reads the
cookie, and the chain and txindex are verified again whenever it changes.
Every RPC is bounded (see rpc), so a stopped or hung Core costs a lookup
at most its budget before the next source is tried.
Default public providers for one chain, without a light client. Creating
it does no I/O; the first fetch builds the Node. A failed build is not
rebuilt for RETRY and its error is returned meanwhile. Untrusted bytes.
Share an explicitly configured, owner-provided runtime Node. Constructing
this wrapper or reading its chain creates no Node, connection or defaults.
Only fetch calls the existing Node; no header/placement authority is added.
Port implemented by a chain verifier, not by an untrusted remote JSON API.
The implementation owns header difficulty, PoW and branch selection. Bodies
remain untrusted bytes and are checked again against the selected header.
Provider-claimed observations used by autonomous clients are a different
contract and do not enter this port by relabelling them as verified.
Untrusted auxiliary parent bytes, not a chain verifier. The chain getter
reads local configuration without I/O. Each fetch must bound its own I/O;
Engine cancellation is cooperative and cannot interrupt a running fetch.