Prefer extensions over loose filename tags by j178 · Pull Request #2092 · j178/prek

j178 · 2026-05-17T13:18:08Z

Closes #2087

Prefer recognized extensions over loose filename-prefix matches during file identification, while preserving exact filename tags and unknown-extension fallbacks.

codecov · 2026-05-17T13:20:03Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.46%. Comparing base (580caee) to head (e931848).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2092      +/-   ##
==========================================
- Coverage   92.47%   92.46%   -0.01%     
==========================================
  Files         119      119              
  Lines       24478    24493      +15     
==========================================
+ Hits        22635    22647      +12     
- Misses       1843     1846       +3

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Copilot

Pull request overview

Updates prek-identify filename tagging to prefer known file extensions over loose filename-prefix matches (e.g., makefile.png no longer inherits makefile/text tags), preventing binary files from being misidentified as text while keeping exact-filename semantics intact.

Changes:

Prefer recognized extension tags over prefix-based filename tag matches, while still preserving exact filename tag matches.
Add focused unit tests covering extension-precedence, unknown-extension fallback, and exact-name + known-extension merging.
Document this intentional behavioral divergence from upstream in docs/diff.md.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
docs/diff.md	Documents the intentional divergence: extensions take precedence over loose filename-prefix matches.
crates/prek-identify/src/lib.rs	Adjusts filename tagging logic to prioritize known extensions and adds unit tests for the new behavior.

prek-ci-bot · 2026-05-17T13:23:44Z

📦 Cargo Bloat Comparison

Binary size change: +0.00% (26.1 MiB → 26.1 MiB)

Expand for cargo-bloat output

Head Branch Results

 File  .text     Size             Crate Name
 1.2%   2.6% 332.0KiB        aws_lc_sys aws_lc_0_39_1_aes_gcm_encrypt_avx512
 1.2%   2.6% 332.0KiB        aws_lc_sys aws_lc_0_39_1_aes_gcm_decrypt_avx512
 0.3%   0.7%  91.9KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.3%   0.7%  83.8KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.2%   0.5%  65.5KiB              prek prek::languages::<impl prek::config::Language>::install::{{closure}}
 0.2%   0.5%  61.1KiB             prek? <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.2%   0.4%  53.3KiB annotate_snippets annotate_snippets::renderer::render::render
 0.2%   0.4%  48.6KiB              prek prek::run::{{closure}}
 0.2%   0.3%  43.3KiB              prek prek::cli::run::run::run::{{closure}}
 0.1%   0.3%  33.3KiB             prek? <prek::cli::RunArgs as clap_builder::derive::Args>::augment_args
 0.1%   0.2%  32.1KiB             prek? <prek::config::_::<impl serde_core::de::Deserialize for prek::config::Config>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map
 0.1%   0.2%  28.7KiB               std core::ptr::drop_in_place<prek::languages::<impl prek::config::Language>::install::{{closure}}>
 0.1%   0.2%  28.0KiB        aws_lc_sys aws_lc_0_39_1_edwards25519_scalarmuldouble_alt
 0.1%   0.2%  27.6KiB      serde_saphyr saphyr_parser_bw::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2%  27.5KiB        aws_lc_sys aws_lc_0_39_1_edwards25519_scalarmuldouble
 0.1%   0.2%  26.2KiB              prek prek::cli::try_repo::try_repo::{{closure}}
 0.1%   0.2%  23.2KiB              prek prek::hooks::meta_hooks::MetaHooks::run::{{closure}}
 0.1%   0.2%  22.5KiB      serde_saphyr saphyr_parser_bw::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2%  22.3KiB         [Unknown] Lp384_montjscalarmul_alt_p384_montjadd
 0.1%   0.2%  21.5KiB      clap_builder clap_builder::parser::parser::Parser::get_matches_with
41.6%  86.3%  10.9MiB                   And 23856 smaller methods. Use -n N to show more.
48.1% 100.0%  12.6MiB                   .text section size, the file size is 26.1MiB

Base Branch Results

 File  .text     Size             Crate Name
 1.2%   2.6% 332.0KiB        aws_lc_sys aws_lc_0_39_1_aes_gcm_encrypt_avx512
 1.2%   2.6% 332.0KiB        aws_lc_sys aws_lc_0_39_1_aes_gcm_decrypt_avx512
 0.3%   0.7%  91.9KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.3%   0.7%  83.8KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.2%   0.5%  65.5KiB              prek prek::languages::<impl prek::config::Language>::install::{{closure}}
 0.2%   0.5%  61.1KiB             prek? <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.2%   0.4%  53.3KiB annotate_snippets annotate_snippets::renderer::render::render
 0.2%   0.4%  48.6KiB              prek prek::run::{{closure}}
 0.2%   0.3%  43.3KiB              prek prek::cli::run::run::run::{{closure}}
 0.1%   0.3%  33.3KiB             prek? <prek::cli::RunArgs as clap_builder::derive::Args>::augment_args
 0.1%   0.2%  32.1KiB             prek? <prek::config::_::<impl serde_core::de::Deserialize for prek::config::Config>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map
 0.1%   0.2%  28.7KiB               std core::ptr::drop_in_place<prek::languages::<impl prek::config::Language>::install::{{closure}}>
 0.1%   0.2%  28.0KiB        aws_lc_sys aws_lc_0_39_1_edwards25519_scalarmuldouble_alt
 0.1%   0.2%  27.6KiB      serde_saphyr saphyr_parser_bw::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2%  27.5KiB        aws_lc_sys aws_lc_0_39_1_edwards25519_scalarmuldouble
 0.1%   0.2%  26.2KiB              prek prek::cli::try_repo::try_repo::{{closure}}
 0.1%   0.2%  23.2KiB              prek prek::hooks::meta_hooks::MetaHooks::run::{{closure}}
 0.1%   0.2%  22.5KiB      serde_saphyr saphyr_parser_bw::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2%  22.3KiB         [Unknown] Lp384_montjscalarmul_alt_p384_montjadd
 0.1%   0.2%  21.5KiB      clap_builder clap_builder::parser::parser::Parser::get_matches_with
41.6%  86.3%  10.9MiB                   And 23856 smaller methods. Use -n N to show more.
48.1% 100.0%  12.6MiB                   .text section size, the file size is 26.1MiB

prek-ci-bot · 2026-05-17T13:23:45Z

⚡️ Hyperfine Benchmarks

Summary: 0 regressions, 2 improvements above the 10% threshold.

Environment

OS: Linux 6.17.0-1013-azure
CPU: 4 cores
prek version: prek 0.4.0+9 (c0e9204 2026-05-17)
Rust version: rustc 1.95.0 (59807616e 2026-04-14)
Hyperfine version: hyperfine 1.20.0

CLI Commands

Benchmarking basic commands in the main repo:

`prek --version`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base --version`	2.2 ± 0.1	2.1	2.6	1.00
`prek-head --version`	2.4 ± 0.3	2.0	3.2	1.06 ± 0.15

`prek list`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base list`	9.0 ± 0.7	8.6	14.0	1.03 ± 0.08
`prek-head list`	8.7 ± 0.1	8.4	9.3	1.00

`prek validate-config .pre-commit-config.yaml`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base validate-config .pre-commit-config.yaml`	3.1 ± 0.1	2.9	3.2	1.07 ± 0.03
`prek-head validate-config .pre-commit-config.yaml`	2.9 ± 0.1	2.8	3.1	1.00

`prek sample-config`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base sample-config`	2.5 ± 0.1	2.5	2.9	1.04 ± 0.15
`prek-head sample-config`	2.4 ± 0.3	2.3	4.7	1.00

Cold vs Warm Runs

Comparing first run (cold) vs subsequent runs (warm cache):

`prek run --all-files (cold - no cache)`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base run --all-files`	135.3 ± 1.6	133.3	137.5	1.00
`prek-head run --all-files`	137.1 ± 1.9	134.0	139.9	1.01 ± 0.02

`prek run --all-files (warm - with cache)`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base run --all-files`	136.3 ± 3.0	132.9	144.5	1.01 ± 0.03
`prek-head run --all-files`	135.2 ± 2.6	132.3	141.0	1.00

Full Hook Suite

Running the builtin hook suite on the benchmark workspace:

`prek run --all-files (full builtin hook suite)`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base run --all-files`	137.3 ± 7.3	130.6	185.3	1.00
`prek-head run --all-files`	137.5 ± 2.6	132.9	143.8	1.00 ± 0.06

Individual Hook Performance

Benchmarking each hook individually on the test repo:

`prek run trailing-whitespace --all-files`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base run trailing-whitespace --all-files`	20.5 ± 0.7	19.8	23.7	1.03 ± 0.05
`prek-head run trailing-whitespace --all-files`	19.9 ± 0.5	19.1	21.5	1.00

`prek run end-of-file-fixer --all-files`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base run end-of-file-fixer --all-files`	36.9 ± 37.8	23.5	205.9	1.41 ± 1.45
`prek-head run end-of-file-fixer --all-files`	26.1 ± 2.3	23.5	31.8	1.00

✅ Performance improvement for prek run end-of-file-fixer --all-files: 29.1700% faster

`prek run check-json --all-files`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base run check-json --all-files`	11.6 ± 0.3	10.9	12.2	1.07 ± 0.04
`prek-head run check-json --all-files`	10.9 ± 0.2	10.5	11.4	1.00

`prek run check-yaml --all-files`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base run check-yaml --all-files`	10.9 ± 0.1	10.7	11.3	1.00
`prek-head run check-yaml --all-files`	10.9 ± 0.2	10.6	11.6	1.01 ± 0.02

`prek run check-toml --all-files`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base run check-toml --all-files`	11.0 ± 0.3	10.5	11.6	1.01 ± 0.04
`prek-head run check-toml --all-files`	10.8 ± 0.2	10.5	11.6	1.00

`prek run check-xml --all-files`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base run check-xml --all-files`	11.0 ± 0.3	10.5	11.6	1.01 ± 0.03
`prek-head run check-xml --all-files`	10.9 ± 0.2	10.6	11.4	1.00

`prek run detect-private-key --all-files`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base run detect-private-key --all-files`	17.1 ± 1.4	15.4	19.7	1.00
`prek-head run detect-private-key --all-files`	17.2 ± 1.4	15.4	21.9	1.01 ± 0.12

`prek run fix-byte-order-marker --all-files`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base run fix-byte-order-marker --all-files`	21.9 ± 1.6	19.4	24.5	1.04 ± 0.10
`prek-head run fix-byte-order-marker --all-files`	21.0 ± 1.3	18.9	23.6	1.00

Installation Performance

Benchmarking hook installation (fast path hooks skip Python setup):

`prek install-hooks (cold - no cache)`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base install-hooks`	4.5 ± 0.0	4.5	4.6	1.02 ± 0.01
`prek-head install-hooks`	4.4 ± 0.0	4.4	4.5	1.00

`prek install-hooks (warm - with cache)`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base install-hooks`	4.6 ± 0.1	4.5	4.7	1.03 ± 0.02
`prek-head install-hooks`	4.4 ± 0.1	4.4	4.5	1.00

File Filtering/Scoping Performance

Testing different file selection modes:

`prek run (staged files only)`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base run`	46.3 ± 0.7	45.2	47.3	1.00
`prek-head run`	46.4 ± 0.9	45.0	47.9	1.00 ± 0.02

`prek run --files '*.json' (specific file type)`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base run --files '*.json'`	8.0 ± 0.1	7.9	8.2	1.02 ± 0.02
`prek-head run --files '*.json'`	7.9 ± 0.1	7.7	8.3	1.00

Workspace Discovery & Initialization

Benchmarking hook discovery and initialization overhead:

`prek run --dry-run --all-files (measures init overhead)`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base run --dry-run --all-files`	10.0 ± 0.1	9.9	10.2	1.02 ± 0.01
`prek-head run --dry-run --all-files`	9.9 ± 0.1	9.7	10.1	1.00

Meta Hooks Performance

Benchmarking meta hooks separately:

`prek run check-hooks-apply --all-files`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base run check-hooks-apply --all-files`	12.2 ± 0.1	12.0	12.3	1.12 ± 0.04
`prek-head run check-hooks-apply --all-files`	10.9 ± 0.4	10.6	11.9	1.00

✅ Performance improvement for prek run check-hooks-apply --all-files: 10.7000% faster

`prek run check-useless-excludes --all-files`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base run check-useless-excludes --all-files`	10.9 ± 0.1	10.7	11.1	1.00
`prek-head run check-useless-excludes --all-files`	11.4 ± 1.3	10.5	13.9	1.04 ± 0.12

`prek run identity --all-files`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`prek-base run identity --all-files`	9.7 ± 0.1	9.6	9.8	1.02 ± 0.01
`prek-head run identity --all-files`	9.5 ± 0.1	9.4	9.8	1.00

Copilot

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

This MR contains the following updates: | Package | Update | Change | |---|---|---| | [prek](https://github.com/j178/prek) | patch | `0.4.0` → `0.4.1` | MR created with the help of [el-capitano/tools/renovate-bot](https://gitlab.com/el-capitano/tools/renovate-bot). **Proposed changes to behavior should be submitted there as MRs.** --- ### Release Notes <details> <summary>j178/prek (prek)</summary> ### [`v0.4.1`](https://github.com/j178/prek/blob/HEAD/CHANGELOG.md#041) [Compare Source](j178/prek@v0.4.0...v0.4.1) Released on 2026-05-20. ##### Enhancements - Fix pre-push range after rebase ([#2089](j178/prek#2089)) - Prefer extensions over loose filename tags ([#2092](j178/prek#2092)) - Skip installs for hooks that will not run ([#2103](j178/prek#2103)) ##### Performance - Optimize meta hook file scans ([#2106](j178/prek#2106)) - Reduce run filtering allocations ([#2090](j178/prek#2090)) ##### Contributors - [@j178](https://github.com/j178) </details> --- ### Configuration 📅 **Schedule**: (UTC) - Branch creation - At any time (no schedule defined) - Automerge - At any time (no schedule defined) 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **Rebasing**: Whenever MR becomes conflicted, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this MR and you won't be reminded about this update again. --- - [ ] If you want to rebase/retry this MR, check this box --- This MR has been generated by [Mend Renovate](https://github.com/renovatebot/renovate).

Copilot AI review requested due to automatic review settings May 17, 2026 13:18

Copilot started reviewing on behalf of j178 May 17, 2026 13:18 View session

Copilot AI reviewed May 17, 2026

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j178 added the enhancement New feature or request label May 17, 2026

j178 force-pushed the identify-extension-precedence branch from d94642a to a9f44f5 Compare May 17, 2026 13:27

Prefer extensions over loose filename tags

e931848

Copilot AI review requested due to automatic review settings May 17, 2026 13:31

j178 force-pushed the identify-extension-precedence branch from a9f44f5 to e931848 Compare May 17, 2026 13:31

Copilot started reviewing on behalf of j178 May 17, 2026 13:31 View session

Copilot AI reviewed May 17, 2026

View reviewed changes

j178 merged commit d7c4503 into master May 17, 2026
33 of 35 checks passed

j178 deleted the identify-extension-precedence branch May 17, 2026 13:37

BrewTestBot mentioned this pull request May 20, 2026

prek 0.4.1 Homebrew/homebrew-core#283700

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Pull request overview

Reviewed changes

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📦 Cargo Bloat Comparison

Head Branch Results

Base Branch Results

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⚡️ Hyperfine Benchmarks

prek --version

prek list

prek validate-config .pre-commit-config.yaml

prek sample-config

prek run --all-files (cold - no cache)

prek run --all-files (warm - with cache)

prek run --all-files (full builtin hook suite)

prek run trailing-whitespace --all-files

prek run end-of-file-fixer --all-files

prek run check-json --all-files

prek run check-yaml --all-files

prek run check-toml --all-files

prek run check-xml --all-files

prek run detect-private-key --all-files

prek run fix-byte-order-marker --all-files

prek install-hooks (cold - no cache)

prek install-hooks (warm - with cache)

prek run (staged files only)

prek run --files '*.json' (specific file type)

prek run --dry-run --all-files (measures init overhead)

prek run check-hooks-apply --all-files

prek run check-useless-excludes --all-files

prek run identity --all-files

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codecov Bot commented May 17, 2026 •

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`prek --version`

`prek list`

`prek validate-config .pre-commit-config.yaml`

`prek sample-config`

`prek run --all-files (cold - no cache)`

`prek run --all-files (warm - with cache)`

`prek run --all-files (full builtin hook suite)`

`prek run trailing-whitespace --all-files`

`prek run end-of-file-fixer --all-files`

`prek run check-json --all-files`

`prek run check-yaml --all-files`

`prek run check-toml --all-files`

`prek run check-xml --all-files`

`prek run detect-private-key --all-files`

`prek run fix-byte-order-marker --all-files`

`prek install-hooks (cold - no cache)`

`prek install-hooks (warm - with cache)`

`prek run (staged files only)`

`prek run --files '*.json' (specific file type)`

`prek run --dry-run --all-files (measures init overhead)`

`prek run check-hooks-apply --all-files`

`prek run check-useless-excludes --all-files`

`prek run identity --all-files`