Refactor query service types into their own crate

[jbearer]

This PR:

Moves query service type definitions into their own crate, which becomes a lighter-weight dependency for downstream crates that want to use the query service but not import the full server backend.

In particular, this allows the light-client crate to not import hotshot-query-service, which in turn will allow (in a future PR) hotshot-query-service to import the light client, which it can use to implement a better fetching provider which retrieves and verifies data from a peer.

[claude]

Claude finished @jbearer's task in 3m 42s —— View job

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Code Review: Refactor query service types into their own crate

• Read repo guidelines and existing review comments
• Analyze PR diff and understand the refactoring
• Review new crate structure and Cargo.toml
• Review type migrations (availability, explorer, node, etc.)
• Review re-exports and backward compatibility in hotshot-query-service
• Review light-client dependency changes
• Post review findings

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Summary

This is a clean, well-executed crate extraction. The hotshot-query-service-types crate cleanly separates type definitions from the server logic, and the re-export pattern in hotshot-query-service preserves full backward compatibility for existing consumers. The motivation is clear and well-articulated: enabling light-client to depend on just the types without pulling in the full query service.

What looks good

• Backward compatibility: Every type moved to the new crate is re-exported from the original crate (e.g., availability/query_data.rs → pub use hotshot_query_service_types::availability::*;), so downstream crates that depend on hotshot-query-service see no API change.

• Generalized SQL impls: The FromRow implementations were previously tied to <Db as Database>::Row (Postgres-specific). They're now generic over R: Row with appropriate trait bounds, making them reusable across different SQL backends. This is a nice improvement.

• Feature gating: The sqlx and testing features in the new crate properly gate optional dependencies (bincode, serde_json, sqlx, hotshot-example-types), keeping the crate lightweight when those features aren't needed.

• Impl consolidation: Blanket impls like HeightIndexed for (T, U) and From<LeafQueryData> for HeaderQueryData are now co-located with their types in the new crate, which is more idiomatic and avoids orphan-rule fragility.

Observations

1. Workspace Cargo.toml formatting noise

The diff reformats many existing dependency lines (wrapping long feature arrays into multi-line format). This is fine style-wise but adds ~60 lines of noise to the diff. Not blocking, just noting it makes the actual changes slightly harder to spot in review.

2. Redundant Error re-export in availability.rs

In hotshot-query-service/src/availability.rs, Error is explicitly re-exported on line 49:

pub use hotshot_query_service_types::availability::Error;

But line 50 does pub use query_data::*; where query_data.rs is just pub use hotshot_query_service_types::availability::*; — which also re-exports Error. Rust handles this fine (both resolve to the same type), but the explicit re-export on line 49 is redundant. Very minor, not worth a separate change.

3. default = ["sqlx"] in the new crate

The new crate defaults to enabling the sqlx feature. Since the stated goal is a "lighter-weight dependency," consider whether sqlx should be opt-in instead of opt-out. The light-client does use sqlx (and brings it in separately), so having it default-on works today, but future consumers wanting only the pure type definitions would need to specify default-features = false. This is a design choice rather than a bug.

Verdict

This is a well-structured refactoring PR. No bugs, no security concerns, no correctness issues found. The type extraction is complete and the backward compatibility layer is solid. Looks good to merge.

[gemini-code-assist]

Code Review

This pull request introduces a new crate, hotshot-query-service-types, to house shared type definitions previously located within the hotshot-query-service crate. This refactoring allows client crates, such as light-client, to depend on these types without pulling in the full server-side logic and dependencies of the query service. I have no feedback to provide as the changes are purely structural and improve dependency management.