perf(search): scan history by recency until N unique

[jbellis]

Inverts the ctrl-r search from "materialize all unique commands, then pick N most recent" to "scan commands by recency until we have N unique ones". Basically the entire change is the SQL query, the rest is scaffolding so we can put filters in the new subquery where they belong.

Measured on a 557k-row history (≈369k distinct commands), empty-query search goes from ~0.78s warm / ~18s cold to ~0.01s warm / ~0.3s cold.

Related PRs I saw:

1. perf: deduplicate empty-query results in Rust instead of SQL #3549: directed at the same problem but breaks semantics as noted by the bot reviewer
2. improve search performance by scanning with the timestamp index iteratively #2698: more code churn, looks like main idea is doing the slow path page-at-a-time, which is better than all-of-history but still worse in principle; corner cases are still bad

Both of the above also split the logic between a SQL query and Rust-side filtering; this one keeps the logic in SQL so the query engine can do its job efficiently.

Checks

• I am happy for maintainers to push small adjustments to this PR, to speed up the review cycle
• I have checked that there are no existing pull requests for the same thing

[github-actions]

Fossier: Vouched and Approved

@ellie vouched for @jbellis. Future PRs from this contributor will be trusted.

[greptile-apps]

Greptile Summary

This PR changes SQLite history search to stop scanning once enough unique commands are found. The main changes are:

• Moves filtering into an inner history query.
• Applies deduplication, ordering, and pagination in an outer query.
• Replaces command grouping with a NOT EXISTS check for the newest row per command.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.
• The reviewed search paths keep filters inside the derived query and apply duplicate handling in the outer query as intended.

Important Files Changed

Filename	Overview
crates/atuin-client/src/database.rs	Refactors search SQL construction around a filtered subquery and outer dedup/order/limit logic.

_{Reviews (1): Last reviewed commit: "perf(search): scan history by recency un..." | Re-trigger Greptile}

[ellie]

looks good, thank you!! nice and neat 🙏

[ellie]

/fossier vouch