Deprecate DelegateCtx put/update/subscribe_contract wrappers; rename get_contract_state (freenet-core#5637) #132

Delegate contract write/subscribe host functions are being removed from freenet-core

freenet/freenet-core#5637 (PR freenet/freenet-core#5638) removes the node-side host functions behind three public DelegateCtx methods:

Why. The write functions wrote the raw Storage and bypassed the node's state-store chokepoints, so every side effect those perform had to be copied by hand. Two omissions reached production (freenet-core #4683, #5479). subscribe_contract only worked for a contract the node already held. A delegate should write by emitting OutboundDelegateMsg::PutContractRequest / UpdateContractRequest, and subscribe with SubscribeContractRequest. Those go through the node's normal path and, since freenet-core #5615, reach the network.

Effect on SDK users. A delegate that calls one of the three removed methods fails to instantiate on a node with #5638, with a named missing-import error. A delegate that only links stdlib is unaffected, because unused imports are dropped. No delegate in river, delta, harvest, ghostkeys, atlas, freenet-bitcoin or raven calls them.

What stdlib should do

1. Deprecate put_contract_state, update_contract_state and subscribe_contract on DelegateCtx, pointing at the outbound-message equivalents, then remove them in a later breaking release. subscribe_contract_checked (0.10.0) imports __frnt__delegate__subscribe_contract_checked, which freenet-core has never provided; it needs the same treatment.
2. Rename the read to say what it does. get_contract_state returns only the state this node already holds, and None means "not held here", not "does not exist". Suggested: add local_contract_state over the same __frnt__delegate__get_contract_state(_len) imports and deprecate get_contract_state as an alias. freenet-core deliberately kept the import names so existing delegates keep loading.
3. Correct delegate_interface.rs (around line 884 in 0.10.0). It currently recommends "the V2 host-function API (the freenet_delegate_contracts import namespace)" as the forward-compatible path for delegates. After #5638 that namespace holds only the read.
4. Stop calling this the "V2" API in docs. There is one delegate API version, DelegateWasmAPIVersion::V1.

Before starting, check: the local, unpushed branch feat/delegate-subscription-api (last commit 2026-08-22) documents these wrappers as the public delegate API, and a separate chore/deprecate-lone-subscribe branch exists. Check with whoever owns them first so the work doesn't collide.

[AI-assisted - Claude]