Pin a Filecoin builtin-actor manifest for a historical decoder
A decoder processing old actor messages must select the actor bundle for the historical network version. Looking only at the Lotus binary currently serving RPC can select the wrong manifest.
Look up the versioned manifest
The example requests the manifest for network version 21. Obtain the actual version for your historical tipset through StateNetworkVersion, then request its manifest CID from the same network endpoint.
{"jsonrpc":"2.0","id":1,"method":"Filecoin.StateActorManifestCID","params":[21]}
Use the manifest as provenance
Store the returned CID, requested network version and network identity beside decoded records. A manifest identifies a bundle, while the specific recipient actor's code determines which actor schema applies. A byte-level decode succeeding under some schema does not establish that the chosen actor version was correct.
docs.filecoin.io StateActorManifestCID · docs.filecoin.io StateNetworkVersion