alknet/tasks/vault/irpc-removal.md

id, name, status, depends_on, scope, risk, impact, level

id	name	status	depends_on	scope	risk	impact	level
vault/irpc-removal	Remove irpc dependency and actor dispatch from vault, convert to direct method calls on VaultServiceHandle	completed		broad	high	component	implementation

Description

Remove the irpc-based actor dispatch from the vault crate and convert to direct method calls on VaultServiceHandle. This is drift item #4 from the vault README drift table and the foundational ADR-025 refactor — it restructures service.rs and protocol.rs fundamentally, which is why most other vault drift tasks depend on this one.

What to remove

• VaultProtocol enum with #[rpc_requests] derive in protocol.rs
• VaultServiceActor in service.rs
• Client<VaultProtocol> usage
• irpc and irpc-derive dependencies from Cargo.toml
• postcard from dev-dependencies (was only needed for the irpc binary path)
• tokio dependency from Cargo.toml (the vault uses std::sync::RwLock, not tokio::sync::RwLock — ADR-025)
• VaultMessage / VaultProtocol re-exports from lib.rs

What to keep / change

• VaultServiceHandle stays — it becomes the sole API. It is already Arc<std::sync::RwLock<VaultServiceInner>> with synchronous methods. The actor path (mpsc channel + oneshot backchannels via irpc's Service trait) is removed entirely.
• VaultServiceError drops Serialize/Deserialize derives (were needed for irpc dispatch — ADR-025 removed that path). It becomes a plain thiserror::Error enum.
• DerivedKey and KeyType stay in protocol.rs — the file is renamed in spirit to "the types module" but the filename stays protocol.rs for continuity. The VaultProtocol enum is removed; DerivedKey/KeyType remain.
• lib.rs re-exports are updated to remove VaultMessage, VaultProtocol, VaultServiceActor and reflect the new public API per the vault README's Public API section.

Public API after this task

Per docs/architecture/crates/vault/README.md → Public API:

pub use mnemonic::{Language, Mnemonic, Seed};
pub use derivation::{DerivationError, ExtendedPrivKey, PATHS};
pub use encryption::{EncryptedData, EncryptionError, EncryptionKey};
pub use encryption::CURRENT_KEY_VERSION;
pub use protocol::{DerivedKey, KeyType};
pub use service::{VaultServiceError, VaultServiceHandle};
pub use cache::CacheConfig;

Cargo.toml changes

Remove from [dependencies]:

• irpc = { workspace = true }
• irpc-derive = { workspace = true }
• tokio = { version = "1", features = ["sync", "rt", "macros"] }

Remove from [dev-dependencies]:

• postcard = { version = "1", features = ["alloc"] }

The vault should have zero async runtime dependency after this task.

Acceptance Criteria

• VaultProtocol enum and #[rpc_requests] derive removed from protocol.rs
• VaultServiceActor removed from service.rs
• Client<VaultProtocol> usage removed
• irpc, irpc-derive, tokio removed from [dependencies] in Cargo.toml
• postcard removed from [dev-dependencies] in Cargo.toml
• VaultServiceError no longer derives Serialize/Deserialize
• lib.rs re-exports match the Public API section of vault README (no VaultMessage, VaultProtocol, VaultServiceActor)
• VaultServiceHandle methods are all synchronous (no async, no .await)
• cargo check succeeds
• cargo clippy succeeds with no warnings
• cargo test succeeds (existing tests updated to remove irpc/postcard usage)
• No tokio dependency remains in the vault Cargo.toml

References

• docs/architecture/crates/vault/README.md — Known Source Drift table item #4, Public API section
• docs/architecture/crates/vault/service.md — Dispatch section, VaultServiceHandle
• docs/architecture/crates/vault/protocol.md — Local-Only by Construction
• docs/architecture/decisions/025-vault-local-only-dispatch.md — ADR-025

Notes

This is the foundational vault refactor. It restructures service.rs and protocol.rs — most other vault drift tasks touch these same files and must follow this one to avoid merge conflicts. The VaultServiceHandle struct already uses std::sync::RwLock with synchronous methods; the actor path is the dead code to remove. After this task, the vault has no async runtime dependency and no RPC framework dependency — it is local-only by construction.

Summary

Removed the irpc-based actor dispatch from the vault crate. VaultServiceHandle (Arc<std::sync::RwLock<VaultServiceInner>>) is now the sole synchronous API. Removed: VaultProtocol enum + #[rpc_requests] derive, VaultServiceActor, VaultService wrapper, Client<VaultProtocol> usage, irpc/irpc-derive/ tokio deps, postcard dev-dep, Serialize/Deserialize on VaultServiceError. lib.rs re-exports match the vault README Public API. The vault is now local-only by construction with zero async runtime dependency. All 58 lib + 14 integration tests pass; clippy clean. Merged to develop.