alknet/tasks/endpoint/registry.md

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

id	name	status	depends_on	scope	risk	impact	level
endpoint/registry	Extract HandlerRegistry from alknet-core/endpoint.rs into alknet-endpoint	completed	endpoint/crate-init	narrow	low	component	implementation

Description

Phase 2, Task 2 of the crate extraction. Extract the HandlerRegistry type from crates/alknet-core/src/endpoint.rs (lines 66-116) into crates/alknet-endpoint/src/registry.rs.

The old code stays in endpoint.rs (duplicated) — no breakage. The new crate is self-contained and builds standalone.

Types to extract

From endpoint.rs lines 66-116:

Type/Function	Lines	Destination
HandlerRegistry struct	66-68	registry.rs
HandlerRegistry::new()	71-75	registry.rs
HandlerRegistry::register()	77-86	registry.rs
HandlerRegistry::get()	88-90	registry.rs
HandlerRegistry::alpn_strings()	92-94	registry.rs
impl Default for HandlerRegistry	97-101	registry.rs
impl Debug for HandlerRegistry	103-116	registry.rs

Adaptations

1. Imports: Update crate::types::ProtocolHandler to alknet_core::types::ProtocolHandler.
2. No other changes: The HandlerRegistry is a pure data structure with no transport deps. It maps ALPN byte strings to ProtocolHandler instances. No feature gates needed — it's always available regardless of which transports are enabled.

Public API

// registry.rs

/// Maps ALPN byte strings to `ProtocolHandler` instances.
/// Registered statically at startup by the assembly layer; the endpoint
/// dispatches by looking up the negotiated ALPN.
pub struct HandlerRegistry {
    handlers: HashMap<&'static [u8], Arc<dyn ProtocolHandler>>,
}

impl HandlerRegistry {
    pub fn new() -> Self;
    /// Insert a handler. Panics if the ALPN is already registered.
    pub fn register(&mut self, handler: Arc<dyn ProtocolHandler>);
    /// Look up a handler by ALPN string.
    pub fn get(&self, alpn: &[u8]) -> Option<&Arc<dyn ProtocolHandler>>;
    /// Return all registered ALPN strings.
    pub fn alpn_strings(&self) -> Vec<Vec<u8>>;
}

What stays in core

The old HandlerRegistry in endpoint.rs lines 66-116 is not deleted — it stays as a duplicate. The prune happens in Phase 4. This task only adds code to alknet-endpoint.

Acceptance Criteria

• crates/alknet-endpoint/src/registry.rs contains HandlerRegistry with all methods
• HandlerRegistry::new() creates an empty registry
• HandlerRegistry::register() inserts a handler, panics on duplicate ALPN
• HandlerRegistry::get() looks up by ALPN, returns None for unknown
• HandlerRegistry::alpn_strings() returns all registered ALPNs
• Default impl delegates to new()
• Debug impl lists ALPNs without exposing handler internals
• All imports use alknet_core:: (not crate::)
• No feature gates (always available)
• cargo check -p alknet-endpoint succeeds
• cargo clippy -p alknet-endpoint succeeds with no warnings
• cargo test -p alknet-core still passes (old code untouched)

References

• docs/research/alknet-crate-extraction/findings.md — Phase 2, registry module
• docs/architecture/crates/endpoint/README.md — HandlerRegistry spec
• crates/alknet-core/src/endpoint.rs — lines 66-116 (source code to extract)

Notes

This is the simplest extraction in Phase 2 — ~50 lines of pure data structure. HandlerRegistry has no transport deps and no feature gates. It's extracted first because AlknetEndpoint::new() takes it as a parameter. The old code in endpoint.rs is NOT deleted — that's Phase 4.

Summary

To be filled on completion