protocol: split async and blocking APIs for fetching refmaps

[djc]

This is just one part of the problem in gix-protocol, but I'm happy that I was able to resolve it with only about +20 lines despite some duplication.

Happy to take feedback if you can articulate it (to save you on refactoring time).

[Byron]

Thanks a lot for keeping these PR coming, it's much appreciated!

Regarding the CI failure, it can be reproduced with cargo test -p gix-protocol --features blocking-client.

There are a few more general questions that arose from a first relatively brief look.

[djc]

Tests should be passing now.

[Byron]

Thanks a lot, I will take a look soon and see to merging it.
Meanwhile, I am unleashing an AI reviewer to see what it can do, please feel free to ignore trash or to ignore it entirely.

[Copilot]

Pull request overview

This PR refactors the gix-protocol crate to split async and blocking APIs for fetching refmaps, removing reliance on the maybe_async macro in favor of explicit method variants. The change introduces a builder pattern with LsRefsCommand and a FetchRefMap enum that defers execution until either fetch_async or fetch_blocking is called.

Key Changes

• Introduced LsRefsCommand struct with separate invoke_async and invoke_blocking methods
• Created FetchRefMap enum to represent either a fetched refmap or a command awaiting execution
• Updated Handshake::fetch_or_extract_refmap to return FetchRefMap instead of directly fetching
• Removed the old ls_refs() function and Action enum in favor of new API structure

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
gix-protocol/src/ls_refs.rs	Replaced ls_refs() function with LsRefsCommand builder pattern, adding separate invoke_async and invoke_blocking methods
gix-protocol/src/handshake/mod.rs	Added FetchRefMap enum and refactored fetch_or_extract_refmap to defer execution with separate async/blocking fetch methods
gix-protocol/src/lib.rs	Updated public API exports from ls_refs function to LsRefsCommand
gix-protocol/src/fetch/refmap/init.rs	Removed RefMap::fetch() method and associated helper functions, moved logic to LsRefsCommand
gix-protocol/src/fetch/types.rs	Updated documentation references to point to new API
gix-protocol/src/fetch/negotiate.rs	Updated documentation references to point to new API
gix/src/remote/connection/ref_map.rs	Updated to use new two-step API with feature-gated fetch_async/fetch_blocking calls
gitoxide-core/src/pack/receive.rs	Updated to use new two-step API with feature-gated fetch_async/fetch_blocking calls
gix-protocol/tests/protocol/fetch/_impl.rs	Updated test delegate trait to use simplified action() method and local RefsAction enum, adapted fetch logic to use LsRefsCommand
gix-protocol/tests/protocol/fetch/mod.rs	Removed unused imports related to old ls_refs API
gix-protocol/tests/protocol/fetch/v2.rs	Updated error matching to reflect flatter error structure

[djc]

AI code review comments were pretty good, addressed all of them.

[Copilot]

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