Fix pretty-format-json CRLF handling

[j178]

Fixes pretty-format-json handling for CRLF files by ignoring newline-style-only differences during comparison and preserving the original newline style on autofix.

Closes #2207

[codecov]

Codecov Report

❌ Patch coverage is 83.33333% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.52%. Comparing base (6166275) to head (4d76b53).

Files with missing lines	Patch %	Lines
...k/src/hooks/pre_commit_hooks/pretty_format_json.rs	83.33%	19 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2210      +/-   ##
==========================================
- Coverage   92.59%   92.52%   -0.08%     
==========================================
  Files         125      125              
  Lines       26587    26698     +111     
==========================================
+ Hits        24617    24701      +84     
- Misses       1970     1997      +27     

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[Copilot]

Pull request overview

This PR fixes the pretty-format-json hook’s behavior on CRLF (Windows) files by ensuring newline-style-only differences don’t trigger a failure and by preserving the original file’s newline style when autofixing, aligning behavior with upstream Python’s text-mode newline normalization.

Changes:

• Compare original vs prettified JSON while treating \r\n / \r as equivalent to \n to avoid false positives on Windows.
• Preserve the file’s original newline style (e.g., CRLF) when --autofix rewrites the file.
• Normalize newlines only for diff output, and add tests covering CRLF, mixed line endings, and CRLF-preserving autofix.

[prek-ci-bot]

📦 Cargo Bloat Comparison

Binary size change: -0.38% (26.6 MiB → 26.5 MiB)

Expand for cargo-bloat output

Head Branch Results

 File  .text     Size             Crate Name
 1.2%   2.5% 332.0KiB        aws_lc_sys aws_lc_0_41_0_aes_gcm_encrypt_avx512
 1.2%   2.5% 332.0KiB        aws_lc_sys aws_lc_0_41_0_aes_gcm_decrypt_avx512
 0.4%   0.7%  95.4KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.3%   0.7%  90.8KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.3%   0.6%  85.1KiB              prek prek::languages::<impl prek::config::Language>::install::{{closure}}
 0.3%   0.6%  78.9KiB             prek? <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.2%   0.4%  49.6KiB              prek prek::run::{{closure}}
 0.2%   0.4%  49.4KiB annotate_snippets annotate_snippets::renderer::render::render
 0.2%   0.3%  44.6KiB             prek? <prek::config::_::<impl serde_core::de::Deserialize for prek::config::Config>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map
 0.2%   0.3%  43.6KiB              prek prek::cli::run::run::run::{{closure}}
 0.1%   0.2%  32.0KiB               std core::ptr::drop_in_place<prek::languages::<impl prek::config::Language>::install::{{closure}}>
 0.1%   0.2%  31.1KiB             prek? <prek::cli::RunOptions as clap_builder::derive::Args>::augment_args
 0.1%   0.2%  29.4KiB     granit_parser granit_parser::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2%  28.3KiB             prek? <prek::config::_::<impl serde_core::de::Deserialize for prek::config::RemoteHook>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map
 0.1%   0.2%  28.0KiB        aws_lc_sys aws_lc_0_41_0_edwards25519_scalarmuldouble_alt
 0.1%   0.2%  27.5KiB        aws_lc_sys aws_lc_0_41_0_edwards25519_scalarmuldouble
 0.1%   0.2%  26.1KiB              prek prek::cli::try_repo::try_repo::{{closure}}
 0.1%   0.2%  24.8KiB             prek? <prek::config::_::<impl serde_core::de::Deserialize for prek::config::LocalHook>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map
 0.1%   0.2%  22.9KiB     granit_parser granit_parser::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2%  22.3KiB         [Unknown] Lp384_montjscalarmul_alt_p384_montjadd
41.8%  86.0%  11.1MiB                   And 24242 smaller methods. Use -n N to show more.
48.6% 100.0%  12.9MiB                   .text section size, the file size is 26.5MiB

Base Branch Results

 File  .text     Size             Crate Name
 1.2%   2.5% 332.0KiB        aws_lc_sys aws_lc_0_41_0_aes_gcm_encrypt_avx512
 1.2%   2.5% 332.0KiB        aws_lc_sys aws_lc_0_41_0_aes_gcm_decrypt_avx512
 0.4%   0.7%  95.4KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.3%   0.7%  90.7KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.3%   0.6%  85.1KiB              prek prek::languages::<impl prek::config::Language>::install::{{closure}}
 0.3%   0.6%  79.4KiB             prek? <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.2%   0.4%  49.7KiB              prek prek::run::{{closure}}
 0.2%   0.4%  49.4KiB annotate_snippets annotate_snippets::renderer::render::render
 0.2%   0.3%  44.6KiB              prek prek::cli::run::run::run::{{closure}}
 0.2%   0.3%  43.9KiB             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%  32.0KiB               std core::ptr::drop_in_place<prek::languages::<impl prek::config::Language>::install::{{closure}}>
 0.1%   0.2%  31.8KiB             prek? <prek::cli::RunOptions as clap_builder::derive::Args>::augment_args
 0.1%   0.2%  29.4KiB     granit_parser granit_parser::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2%  28.3KiB             prek? <prek::config::_::<impl serde_core::de::Deserialize for prek::config::RemoteHook>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map
 0.1%   0.2%  28.0KiB        aws_lc_sys aws_lc_0_41_0_edwards25519_scalarmuldouble_alt
 0.1%   0.2%  27.5KiB        aws_lc_sys aws_lc_0_41_0_edwards25519_scalarmuldouble
 0.1%   0.2%  26.2KiB              prek prek::cli::try_repo::try_repo::{{closure}}
 0.1%   0.2%  24.8KiB             prek? <prek::config::_::<impl serde_core::de::Deserialize for prek::config::LocalHook>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map
 0.1%   0.2%  22.9KiB     granit_parser granit_parser::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2%  22.3KiB         [Unknown] Lp384_montjscalarmul_alt_p384_montjadd
41.8%  86.0%  11.1MiB                   And 24265 smaller methods. Use -n N to show more.
48.6% 100.0%  12.9MiB                   .text section size, the file size is 26.6MiB

[prek-ci-bot]

⚡️ Hyperfine Benchmarks

Summary: 0 regressions, 1 improvements above the 10% threshold.

Environment

• OS: Linux 6.17.0-1018-azure
• CPU: 4 cores
• prek version: prek 0.4.4+45 (be303ee 2026-06-13)
• Rust version: rustc 1.96.0 (ac68faa20 2026-05-25)
• 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	2.1 ± 0.1	2.0	2.8	1.00
prek-head --version	2.2 ± 0.1	2.0	2.5	1.02 ± 0.06

prek list

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base list	8.9 ± 0.1	8.7	9.4	1.00
prek-head list	9.4 ± 0.6	8.7	10.5	1.05 ± 0.07

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	3.0	3.4	1.06 ± 0.04
prek-head validate-config .pre-commit-config.yaml	3.0 ± 0.1	2.8	3.2	1.00

prek sample-config

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base sample-config	2.5 ± 0.5	2.3	5.8	1.03 ± 0.21
prek-head sample-config	2.4 ± 0.0	2.3	2.5	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	74.2 ± 3.2	69.2	77.8	1.01 ± 0.07
prek-head run --all-files	73.4 ± 4.3	69.3	81.4	1.00

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

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run --all-files	73.1 ± 5.8	69.1	95.7	1.00
prek-head run --all-files	73.6 ± 2.9	69.4	78.3	1.01 ± 0.09

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	73.0 ± 2.5	69.0	77.1	1.00
prek-head run --all-files	73.4 ± 2.7	68.6	81.2	1.00 ± 0.05

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	19.7 ± 0.4	18.9	20.4	1.00
prek-head run trailing-whitespace --all-files	19.8 ± 0.4	19.1	20.5	1.01 ± 0.03

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	26.2 ± 2.2	23.5	30.0	1.02 ± 0.11
prek-head run end-of-file-fixer --all-files	25.6 ± 1.6	23.4	28.7	1.00

prek run check-json --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-json --all-files	7.7 ± 0.3	7.1	8.3	1.01 ± 0.05
prek-head run check-json --all-files	7.6 ± 0.2	7.2	8.1	1.00

prek run check-yaml --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-yaml --all-files	7.5 ± 0.2	7.2	7.8	1.02 ± 0.03
prek-head run check-yaml --all-files	7.3 ± 0.2	7.1	7.7	1.00

prek run check-toml --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-toml --all-files	7.5 ± 0.2	7.1	8.1	1.00
prek-head run check-toml --all-files	7.5 ± 0.3	7.1	8.5	1.01 ± 0.05

prek run check-xml --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-xml --all-files	7.5 ± 0.3	7.0	8.2	1.00
prek-head run check-xml --all-files	7.6 ± 0.3	7.1	8.4	1.01 ± 0.05

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

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run detect-private-key --all-files	13.3 ± 1.1	11.6	15.8	1.00
prek-head run detect-private-key --all-files	14.2 ± 1.4	11.8	18.5	1.07 ± 0.14

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	18.6 ± 0.8	17.2	20.2	1.01 ± 0.06
prek-head run fix-byte-order-marker --all-files	18.4 ± 0.7	17.0	19.6	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	4.4 ± 0.1	4.3	4.4	1.01 ± 0.02
prek-head install-hooks	4.3 ± 0.1	4.3	4.4	1.00

prek install-hooks (warm - with cache)

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base install-hooks	4.4 ± 0.1	4.3	4.5	1.02 ± 0.03
prek-head install-hooks	4.3 ± 0.1	4.2	4.4	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	37.7 ± 1.2	35.8	39.7	1.00
prek-head run	39.3 ± 8.7	35.3	75.7	1.04 ± 0.23

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

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run --files '*.json'	7.8 ± 0.1	7.6	8.1	1.00
prek-head run --files '*.json'	8.0 ± 0.2	7.8	8.8	1.03 ± 0.03

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	6.7 ± 0.1	6.6	6.8	1.00
prek-head run --dry-run --all-files	6.8 ± 0.2	6.6	7.4	1.01 ± 0.03

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	11.8 ± 0.1	11.7	12.1	1.00 ± 0.01
prek-head run check-hooks-apply --all-files	11.8 ± 0.1	11.6	12.1	1.00

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

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-useless-excludes --all-files	11.7 ± 0.1	11.5	11.9	1.12 ± 0.02
prek-head run check-useless-excludes --all-files	10.5 ± 0.1	10.2	10.7	1.00

✅ Performance improvement for prek run check-useless-excludes --all-files: 10.7500% faster

prek run identity --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run identity --all-files	9.9 ± 0.3	9.5	10.4	1.02 ± 0.03
prek-head run identity --all-files	9.7 ± 0.1	9.5	10.0	1.00