fix(rust-sdk): ag-ui-core — round-trip non-UUID Thread/Run/Message/Agent IDs

[martinsotirov]

Fixes #2195.

What

ThreadId/RunId/MessageId/AgentId were strict Uuid newtypes whose FromStr/Deserialize rejected any non-UUID string. The AG-UI protocol (and the TS @ag-ui/core) treat these IDs as plain strings, so any server with non-UUID IDs (LangGraph lc_run--…, composite/namespaced IDs) couldn't round-trip events through the Rust SDK.

This makes the newtypes accept and round-trip arbitrary strings — a UUID-v5 hash backs the as_uuid() view while the original string is preserved for Display/serialize — so valid UUIDs behave exactly as before and non-UUID IDs now interoperate.

Provenance

The fix itself is @MikeSchirtzinger's work from the server-crate branch (#972), commits 90b5205e + 5e50a9f3. It's currently entangled in that large, unmerged PR. This PR extracts just the ids.rs change, rebased onto current main, so it can land independently of the server crate. Full credit to Mike (co-authored).

Changes (minimal + focused)

• crates/ag-ui-core/src/types/ids.rs — the round-trip implementation + tests.
• workspace Cargo.toml — enable the uuid v5 feature (needed for new_v5). Nothing else.

Verification

Against current main (edition 2024): cargo build -p ag-ui-core and cargo test -p ag-ui-core both pass, including test_serialize_roundtrip_arbitrary_string, test_run_id_deserialize_non_uuid_string, test_message_id_deserialize_langgraph_format.

Happy to adjust scope or squash as maintainers prefer.

[martinsotirov]

Pushed a follow-up commit (20a6248e): made the protocol string the identity for PartialEq/Hash/Serialize/Display. The initial extraction keyed these on the UUID-v5 backing value, so two distinct strings colliding under v5 would compare equal and collide as HashSet/HashMap keys — and ag-ui-client uses HashSet<&MessageId>. The UUID is now a derived compatibility view only (as_uuid()/From<Uuid>/PartialEq<Uuid> unchanged), and new() preserves the exact input string for both UUID- and non-UUID-shaped inputs, so different spellings of the same UUID stay distinct — matching the plain-string IDs in the TS SDK. Also synced Cargo.lock for the uuid v5 feature (sha1_smol), which the first commit left stale.

cargo test -p ag-ui-core (26 ID tests) and cargo test -p ag-ui-client pass. Happy to squash the two commits if you'd prefer a single one.