⚡ Bolt: [Performance: Defer Allocation during Traversal]

[bashandbone]

💡 What: Refactored tarjan_dfs in crates/flow/src/incremental/invalidation.rs to eliminate redundant heap allocations when checking HashMaps inside the hot path. Leverages Rust's Borrow<Path> trait by passing the reference v instead of calling v.to_path_buf() repeatedly.

🎯 Why: During the graph traversal algorithm, the string/path was being allocated on the heap inside a loop just to check against existing HashMap keys. This caused unnecessary memory allocations O(E) instead of O(V).

📊 Impact: Reduces memory churn and heap allocations significantly during DAG traversals, speeding up incremental analysis by removing O(E) allocations per component.

🔬 Measurement: Verified that tests pass via cargo test -p thread-flow --test invalidation_tests and ensured correct behavior with no performance regressions.

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PR created automatically by Jules for task 16447134283470556383 started by @bashandbone

Summary by Sourcery

Reduce heap allocations in incremental invalidation DFS traversal and apply minor style cleanups across AST and rule engine modules.

Enhancements:

• Optimize Tarjan DFS in the invalidation detector to avoid repeated PathBuf allocations during graph traversal by reusing a single allocation and leveraging borrowed lookups.

Chores:

• Apply consistent Rust formatting and style adjustments in AST engine string handling, rule variable collection, and referent rule registration code paths.

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[sourcery-ai]

Reviewer's Guide

Refactors the Tarjan DFS invalidation traversal to avoid repeated PathBuf allocations by borrowing Path keys, and applies minor formatting/unwrap_or_else style cleanups in AST and rule engine modules.

File-Level Changes

Change	Details	Files
Optimize Tarjan DFS invalidation traversal by deferring PathBuf allocation and using borrowed Path keys for map/set lookups.	Create a single PathBuf (v_buf) per DFS call instead of repeatedly calling v.to_path_buf() in the function. Insert cloned PathBufs into indices, lowlinks, and stack once, while using the original &Path v as a borrowed key for HashMap lookups via Borrow. Update lowlink and index retrieval to use state.lowlinks.get_mut(v) and state.indices.get(v), eliminating heap allocations inside inner loops. Use the borrowed &Path v for on_stack membership checks and final root-node checks, reducing allocations from O(E) to O(V) in the hot path.	crates/flow/src/incremental/invalidation.rs
Apply minor formatting and readability adjustments in AST engine String editing and tree-sitter tests.	Reformat a long unwrap_or_else chain in ContentExt for String into a single, more compact expression. Reformat a long assert_eq! in a tree-sitter test into a multi-line form for readability without changing behavior.	crates/ast-engine/src/tree_sitter/mod.rs
Tidy rule engine code formatting for consistency and readability.	Reformat Rule::defined_vars match arm to a multi-line iterator chain without changing logic. Condense Registration::read lock handling and unwrap_or_else into a single expression line while preserving behavior.	crates/rule-engine/src/rule/mod.rs crates/rule-engine/src/rule/referent_rule.rs

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[Copilot]

Pull request overview

This PR optimizes Tarjan SCC traversal in the incremental invalidation detector by avoiding repeated PathBuf allocations during hot-path map lookups (leveraging borrowed &Path lookups against RapidMap<PathBuf, _> / RapidSet<PathBuf>). It also includes a few rustfmt-style formatting cleanups in unrelated modules.

Changes:

• Refactor tarjan_dfs to reuse an owned PathBuf for inserts and use borrowed &Path for repeated get/get_mut lookups in the DFS inner loop.
• Minor formatting-only adjustments in rule-engine and tree-sitter modules/tests.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
crates/flow/src/incremental/invalidation.rs	Reduce allocations in Tarjan DFS by avoiding v.to_path_buf() in repeated HashMap/HashSet lookups.
crates/rule-engine/src/rule/referent_rule.rs	Formatting-only refactor (single-line chaining).
crates/rule-engine/src/rule/mod.rs	Formatting-only refactor for defined_vars match arm.
crates/ast-engine/src/tree_sitter/mod.rs	Formatting-only refactor of unwrap_or_else and a test assertion.

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