feat(generated-detect): suppress bug-fix attribution for auto-generated files - #19

The current GENERATED_SUBSTRINGS patterns (e.g., "/generated/") will fail to match generated directories located at the root of the repository because relative paths in git often lack a leading slash (e.g., generated/types.rs). While the slashes are intended to prevent false positives like regenerate_token.rs, they make the heuristic too conservative for top-level directories.

Fixed in 05b8368 — switched to component-wise matching: split path on / and compare each component to the known generated dir names. Top-level generated/types.rs now matches, while regenerate_token.rs and degenerate_input.rs stay rejected. New test top_level_generated_directories_hit covers 5 root-level cases.

Instead of a substring scan with slashes, consider splitting the normalized path into components and checking if any component exactly matches a set of known generated directory names. This is more robust as it correctly identifies top-level directories while still avoiding partial matches like regenerate.

    // Check if any path component matches a known generated directory name.
    if normalized.split('/').any(|s| matches!(s, "generated" | "__generated__" | ".generated" | "autogenerated" | "auto-generated" | "codegen" | "grpc-gen" | "grpc_gen")) {
        return true;
    }

Done in 05b8368 — exactly this: for component in normalized.split('/') checked against GENERATED_DIR_COMPONENTS. Cleaner intent and correctly handles repo-root paths.

Iterating through a list of regexes and calling is_match on each is less efficient than using a RegexSet. A RegexSet can match multiple patterns in a single scan of the input string.

Done in 05b8368 — Vec<Regex> + per-pattern is_match loop replaced with a single RegexSet. One DFA, one scan.

Generated flag never refreshed for pre-existing file entries

Medium Severity

The generated flag is only set inside or_insert_with, which runs exclusively when a FileActivity entry is first created. During an incremental update on a map deserialized from before this feature, pre-existing entries retain generated: false (from #[serde(default)]) because or_insert_with is not invoked for them. This means bug-fix attribution is silently not suppressed for those generated files — exactly the scenario the feature aims to prevent. The flag needs to be unconditionally refreshed after the or_insert_with call.

 

^{Reviewed by Cursor Bugbot for commit 6522feb. Configure here.}

Fixed in 05b8368 — generated is now refreshed on every visit, not just on insert. Comment explains why (deserialized maps from before the field existed have generated: false from #[serde(default)] and would never get marked otherwise). Test test_merge_delta_refreshes_generated_flag_on_existing_entries pre-seeds an entry with generated: false and asserts the flag flips after merge_delta.

Directory markers miss top-level generated directories

Low Severity

Every entry in GENERATED_SUBSTRINGS starts with / (e.g., "/generated/"), and matching uses normalized.contains(needle). Git paths are repo-root-relative with no leading slash, so a file in a top-level generated directory like "generated/types.rs" does not contain "/generated/" and is silently missed. Only nested paths like "src/generated/types.rs" match. This affects all eight directory markers equally — codegen/, __generated__/, etc. at the repo root all produce false negatives.

 

^{Reviewed by Cursor Bugbot for commit 6522feb. Configure here.}

Fixed in 05b8368 — switched from substring scan with leading slashes to component-wise matching. Top-level generated/types.rs, codegen/foo.go, etc. now register correctly while substring collisions like regenerate_token.rs stay rejected.