feat(xmtp_proto): XIP-83 Subscribe protos (bidi mutable subscription)

[tylerhawkes]

Stack 1/4 of the XIP-83 bidi client lane: #3769 → #3770 → #3771 → #3772.

Regenerated xmtp.mls.api.v1 from xmtp/proto#337: the bidirectional Subscribe RPC with versioned SubscribeRequest/SubscribeResponse, id-based Mutate (cursors, history_only), Ping/Pong, TopicsLive, CATCHUP_COMPLETE, and STARTED capabilities. Purely additive (+1,896 generated lines); proto_version pinned to that branch's sha — draft until the proto PR merges.

🤖 Generated with Claude Code

Note

Add XIP-83 bidirectional subscribe protos to MLS API v1

• Adds SubscribeRequest and SubscribeResponse proto messages implementing XIP-83 bidirectional mutable subscriptions, including nested types for Mutate, Ping/Pong, Started, Messages, TopicsLive, and CatchupComplete.
• Extends the MlsApi server trait with a new bidirectional streaming subscribe method and server-side routing for /xmtp.mls.api.v1.MlsApi/Subscribe.
• Adds serde implementations for all new types, encoding bytes fields as base64 and supporting both snake_case and camelCase field names.
• Updates the pinned proto descriptor hash in proto_version.

^{Macroscope summarized 21b315c.}

[claude]

Claude finished @tylerhawkes's task —— View job

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Code Review Complete ✓

Reviewed on: 2026-06-15 20:22 UTC

This PR adds XIP-83 bidirectional Subscribe RPC protos - purely generated code from xmtp/proto#337. The changes look solid overall for generated protobuf code.

Summary

✅ Code Generation: The generated Rust code follows standard prost patterns correctly - proper derives, name implementations, and type URLs.

✅ API Design: The new bidirectional Subscribe RPC is well-structured with:

• Versioned request/response envelopes (V1)
• Mutable subscription via Mutate (add/remove topics with cursors)
• history_only mode for bounded catch-up
• Ping/Pong keepalive mechanism
• TopicsLive and CatchupComplete markers
• Started frame with capabilities negotiation

✅ Proto Version: Pinned to ac2aa57f7482e354b1903f562203169eb1cc479f from the proto branch - appropriate for draft status until xmtp/proto#337 merges.

Key Points

No issues found. The generated code is clean and follows expected patterns for prost-generated types.

Integration Notes (for downstream PRs #3770-#3772):

1. The Mutate.Subscription.id_cursor field (line 825) uses u64 - ensure client code handles cursor bookkeeping correctly, especially the seeding from WelcomeMetadata.message_cursor mentioned in comments
2. The bidirectional stream signature at xmtp.mls.api.v1.rs:1409-1412 uses tonic::Streaming<SubscribeRequest> input - client implementations will need proper stream management for mutable subscriptions
3. The history_only flag (line 805) combined with half-closing enables sync mode - ensure this boundary condition is tested in integration
4. Server keepalive_interval_ms (line 927) requires client-side timeout/reap logic

Coverage: Codecov shows 84.46% coverage with no regression - appropriate since this is pure proto generation without logic yet.

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Files reviewed:

• crates/xmtp_proto/proto_version:1
• crates/xmtp_proto/src/gen/xmtp.mls.api.v1.rs:765-1103 (Subscribe structures)

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.44%. Comparing base (8ad390a) to head (21b315c).
⚠️ Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3769      +/-   ##
==========================================
- Coverage   84.45%   84.44%   -0.02%     
==========================================
  Files         408      408              
  Lines       59772    59880     +108     
==========================================
+ Hits        50483    50567      +84     
- Misses       9289     9313      +24     

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[macroscopeapp]

Approvability

Verdict: Approved

Auto-generated protobuf definitions adding new Subscribe RPC types for XIP-83. All files are generated code owned by the author, and changes are purely additive interface definitions with no runtime behavior impact in this codebase.

^{You can customize Macroscope's approvability policy. Learn more.}