Improve subprocess error messages

[j178]

For #2256

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[codecov]

Codecov Report

❌ Patch coverage is 96.67458% with 14 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.92%. Comparing base (a538d83) to head (deb7054).

Files with missing lines	Patch %	Lines
crates/prek/src/process.rs	97.11%	6 Missing ⚠️
crates/prek/src/git.rs	90.69%	4 Missing ⚠️
crates/prek/src/cli/try_repo.rs	87.50%	1 Missing ⚠️
crates/prek/src/languages/haskell.rs	75.00%	1 Missing ⚠️
crates/prek/src/languages/pygrep/pygrep.rs	66.66%	1 Missing ⚠️
crates/prek/src/languages/ruby/gem.rs	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2257      +/-   ##
==========================================
+ Coverage   92.74%   92.92%   +0.18%     
==========================================
  Files         127      127              
  Lines       27518    27583      +65     
==========================================
+ Hits        25522    25632     +110     
+ Misses       1996     1951      -45     

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[prek-ci-bot]

📦 Cargo Bloat Comparison

Binary size change: +0.00% (26.8 MiB → 26.8 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
 0.3%   0.7%  95.6KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.3%   0.7%  92.0KiB              prek prek::languages::<impl prek::config::Language>::install::{{closure}}
 0.3%   0.7%  91.4KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.2%   0.5%  65.2KiB             prek? <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.2%   0.4%  49.4KiB annotate_snippets annotate_snippets::renderer::render::render
 0.2%   0.4%  48.9KiB              prek prek::run::{{closure}}
 0.2%   0.3%  43.6KiB              prek prek::cli::run::run::run::{{closure}}
 0.2%   0.3%  42.6KiB             prek? <prek::config::_::<impl serde_core::de::Deserialize for prek::config::Config>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map
 0.1%   0.3%  34.2KiB               std core::ptr::drop_in_place<prek::languages::<impl prek::config::Language>::install::{{closure}}>
 0.1%   0.3%  33.4KiB              prek prek::archive::unpack::{{closure}}
 0.1%   0.2%  31.9KiB             prek? <prek::cli::RunOptions as clap_builder::derive::Args>::augment_args
 0.1%   0.2%  29.8KiB     granit_parser granit_parser::scanner::Scanner<T>::fetch_more_tokens
 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%  27.3KiB             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%  25.9KiB              prek prek::cli::try_repo::try_repo::{{closure}}
 0.1%   0.2%  25.0KiB              prek prek::languages::ruby::installer::RubyInstaller::install::{{closure}}
 0.1%   0.2%  24.7KiB             prek? <prek::config::_::<impl serde_core::de::Deserialize for prek::config::LocalHook>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map
42.0%  86.1%  11.2MiB                   And 24558 smaller methods. Use -n N to show more.
48.8% 100.0%  13.0MiB                   .text section size, the file size is 26.8MiB

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%  96.0KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.3%   0.7%  92.9KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.3%   0.7%  92.0KiB              prek prek::languages::<impl prek::config::Language>::install::{{closure}}
 0.2%   0.5%  66.2KiB             prek? <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.2%   0.4%  49.8KiB              prek prek::run::{{closure}}
 0.2%   0.4%  49.4KiB annotate_snippets annotate_snippets::renderer::render::render
 0.2%   0.3%  44.1KiB              prek prek::cli::run::run::run::{{closure}}
 0.2%   0.3%  44.0KiB             prek? <prek::config::_::<impl serde_core::de::Deserialize for prek::config::Config>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map
 0.1%   0.3%  34.3KiB               std core::ptr::drop_in_place<prek::languages::<impl prek::config::Language>::install::{{closure}}>
 0.1%   0.2%  32.8KiB              prek prek::archive::unpack::{{closure}}
 0.1%   0.2%  32.1KiB             prek? <prek::cli::RunOptions as clap_builder::derive::Args>::augment_args
 0.1%   0.2%  29.8KiB     granit_parser granit_parser::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2%  28.0KiB        aws_lc_sys aws_lc_0_41_0_edwards25519_scalarmuldouble_alt
 0.1%   0.2%  27.7KiB             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%  27.5KiB        aws_lc_sys aws_lc_0_41_0_edwards25519_scalarmuldouble
 0.1%   0.2%  27.1KiB              prek prek::cli::try_repo::try_repo::{{closure}}
 0.1%   0.2%  25.1KiB              prek prek::languages::ruby::installer::RubyInstaller::install::{{closure}}
 0.1%   0.2%  24.1KiB             prek? <prek::config::_::<impl serde_core::de::Deserialize for prek::config::LocalHook>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map
42.0%  86.1%  11.2MiB                   And 24562 smaller methods. Use -n N to show more.
48.7% 100.0%  13.0MiB                   .text section size, the file size is 26.8MiB

[prek-ci-bot]

⚡️ Hyperfine Benchmarks

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

Environment

• OS: Linux 6.17.0-1018-azure
• CPU: 4 cores
• prek version: prek 0.4.5+27 (5b2aabe 2026-06-27)
• 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	1.8 ± 0.1	1.7	2.5	1.05 ± 0.08
prek-head --version	1.7 ± 0.1	1.6	2.2	1.00

prek list

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base list	7.9 ± 0.1	7.6	8.5	1.02 ± 0.02
prek-head list	7.8 ± 0.1	7.5	8.0	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	2.6 ± 0.1	2.5	3.1	1.04 ± 0.04
prek-head validate-config .pre-commit-config.yaml	2.5 ± 0.1	2.4	2.7	1.00

prek sample-config

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base sample-config	2.1 ± 0.0	2.0	2.2	1.02 ± 0.03
prek-head sample-config	2.0 ± 0.0	1.9	2.1	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	53.5 ± 1.6	50.9	56.7	1.01 ± 0.04
prek-head run --all-files	52.8 ± 1.3	50.5	54.2	1.00

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

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run --all-files	52.3 ± 1.3	50.4	54.6	1.00 ± 0.04
prek-head run --all-files	52.2 ± 1.4	50.3	55.1	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	53.1 ± 1.7	50.0	56.5	1.01 ± 0.04
prek-head run --all-files	52.7 ± 1.3	50.3	55.8	1.00

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	14.2 ± 0.2	13.7	14.6	1.01 ± 0.02
prek-head run trailing-whitespace --all-files	14.0 ± 0.2	13.6	14.6	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	19.5 ± 0.9	17.5	21.1	1.00
prek-head run end-of-file-fixer --all-files	19.5 ± 1.7	17.5	25.3	1.00 ± 0.10

prek run check-json --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-json --all-files	5.9 ± 0.2	5.6	6.2	1.02 ± 0.04
prek-head run check-json --all-files	5.8 ± 0.2	5.5	6.0	1.00

prek run check-yaml --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-yaml --all-files	5.9 ± 0.1	5.6	6.2	1.03 ± 0.03
prek-head run check-yaml --all-files	5.7 ± 0.1	5.5	6.1	1.00

prek run check-toml --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-toml --all-files	5.8 ± 0.2	5.5	6.3	1.03 ± 0.05
prek-head run check-toml --all-files	5.6 ± 0.2	5.3	6.0	1.00

prek run check-xml --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-xml --all-files	5.8 ± 0.2	5.4	6.2	1.01 ± 0.05
prek-head run check-xml --all-files	5.7 ± 0.2	5.3	6.1	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	10.4 ± 0.6	9.5	11.8	1.02 ± 0.08
prek-head run detect-private-key --all-files	10.2 ± 0.6	9.4	11.6	1.00

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	13.6 ± 0.4	12.9	14.5	1.01 ± 0.04
prek-head run fix-byte-order-marker --all-files	13.6 ± 0.4	12.9	14.5	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	3.7 ± 0.1	3.6	3.8	1.04 ± 0.04
prek-head install-hooks	3.6 ± 0.1	3.4	3.7	1.00

prek install-hooks (warm - with cache)

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base install-hooks	3.7 ± 0.1	3.6	3.7	1.03 ± 0.02
prek-head install-hooks	3.5 ± 0.0	3.5	3.6	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	26.9 ± 0.6	26.2	28.6	1.00 ± 0.03
prek-head run	26.8 ± 0.6	26.0	28.0	1.00

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

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run --files '*.json'	6.0 ± 0.2	5.8	6.3	1.04 ± 0.03
prek-head run --files '*.json'	5.8 ± 0.1	5.6	5.9	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	5.2 ± 0.1	5.1	5.3	1.00 ± 0.03
prek-head run --dry-run --all-files	5.2 ± 0.1	4.9	5.5	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	8.4 ± 0.2	8.1	8.8	1.05 ± 0.04
prek-head run check-hooks-apply --all-files	8.0 ± 0.1	7.9	8.3	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	8.1 ± 0.2	8.0	8.5	1.02 ± 0.02
prek-head run check-useless-excludes --all-files	7.9 ± 0.1	7.7	8.1	1.00

prek run identity --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run identity --all-files	7.4 ± 0.1	7.3	7.7	1.01 ± 0.02
prek-head run identity --all-files	7.4 ± 0.1	7.2	7.8	1.00

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