Skip installs for hooks that will not run

[j178]

Closes #1459.

This refactors prek run to collect files and apply hook filters before resolving install environments. Hooks that will not run no longer cause their environments to be installed.

[codecov]

Codecov Report

❌ Patch coverage is 95.46120% with 31 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.34%. Comparing base (2a0da57) to head (24621fc).

Files with missing lines	Patch %	Lines
crates/prek/src/cli/run/install.rs	89.26%	22 Missing ⚠️
crates/prek/src/cli/run/run.rs	98.01%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2103      +/-   ##
==========================================
- Coverage   92.49%   92.34%   -0.15%     
==========================================
  Files         119      120       +1     
  Lines       24519    24683     +164     
==========================================
+ Hits        22678    22793     +115     
- Misses       1841     1890      +49     

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[prek-ci-bot]

📦 Cargo Bloat Comparison

Binary size change: +0.38% (26.0 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_41_0_aes_gcm_encrypt_avx512
 1.2%   2.6% 332.0KiB        aws_lc_sys aws_lc_0_41_0_aes_gcm_decrypt_avx512
 0.3%   0.7%  91.9KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.3%   0.7%  83.9KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.3%   0.6%  74.8KiB             prek? <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.3%   0.5%  70.0KiB              prek prek::languages::<impl prek::config::Language>::install::{{closure}}
 0.2%   0.4%  51.3KiB annotate_snippets annotate_snippets::renderer::render::render
 0.2%   0.3%  43.0KiB              prek prek::cli::run::run::run::{{closure}}
 0.1%   0.3%  35.9KiB              prek prek::run::{{closure}}
 0.1%   0.3%  33.0KiB             prek? <prek::cli::RunArgs as clap_builder::derive::Args>::augment_args
 0.1%   0.2%  30.4KiB             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%  29.8KiB               std core::ptr::drop_in_place<prek::languages::<impl prek::config::Language>::install::{{closure}}>
 0.1%   0.2%  28.1KiB      serde_saphyr 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%  26.3KiB              prek prek::cli::try_repo::try_repo::{{closure}}
 0.1%   0.2%  23.1KiB              prek prek::hooks::meta_hooks::MetaHooks::run::{{closure}}
 0.1%   0.2%  23.0KiB      serde_saphyr granit_parser::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
41.5%  86.2%  10.8MiB                   And 23887 smaller methods. Use -n N to show more.
48.1% 100.0%  12.5MiB                   .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_41_0_aes_gcm_encrypt_avx512
 1.2%   2.6% 332.0KiB        aws_lc_sys aws_lc_0_41_0_aes_gcm_decrypt_avx512
 0.3%   0.7%  91.9KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.3%   0.7%  83.7KiB              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%  60.9KiB             prek? <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.2%   0.4%  51.3KiB annotate_snippets annotate_snippets::renderer::render::render
 0.2%   0.4%  48.5KiB              prek prek::run::{{closure}}
 0.1%   0.3%  39.8KiB              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%  31.2KiB             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%  28.1KiB      serde_saphyr 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%  26.5KiB              prek prek::cli::try_repo::try_repo::{{closure}}
 0.1%   0.2%  23.1KiB              prek prek::hooks::meta_hooks::MetaHooks::run::{{closure}}
 0.1%   0.2%  23.0KiB      serde_saphyr granit_parser::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2%  22.6KiB             prek? <prek::cli::Command as clap_builder::derive::FromArgMatches>::from_arg_matches_mut
 0.1%   0.2%  22.3KiB         [Unknown] Lp384_montjscalarmul_alt_p384_montjadd
41.5%  86.2%  10.8MiB                   And 23795 smaller methods. Use -n N to show more.
48.1% 100.0%  12.5MiB                   .text section size, the file size is 26.0MiB

[prek-ci-bot]

⚡️ Hyperfine Benchmarks

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

Environment

• OS: Linux 6.17.0-1013-azure
• CPU: 4 cores
• prek version: prek 0.4.0+29 (06035a2 2026-05-19)
• 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	2.3 ± 0.2	2.2	3.8	1.08 ± 0.09
prek-head --version	2.1 ± 0.1	2.0	2.5	1.00

prek list

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base list	9.4 ± 0.2	9.0	9.8	1.02 ± 0.04
prek-head list	9.2 ± 0.3	8.6	10.9	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	3.2 ± 0.1	3.0	3.5	1.01 ± 0.18
prek-head validate-config .pre-commit-config.yaml	3.1 ± 0.6	2.9	6.9	1.00

prek sample-config

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base sample-config	2.7 ± 0.0	2.6	2.8	1.06 ± 0.08
prek-head sample-config	2.5 ± 0.2	2.4	3.8	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	146.6 ± 2.5	142.3	150.2	1.00
prek-head run --all-files	149.2 ± 4.8	143.2	159.3	1.02 ± 0.04

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

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run --all-files	148.4 ± 2.6	143.0	152.9	1.02 ± 0.03
prek-head run --all-files	145.9 ± 3.8	138.2	152.7	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	148.4 ± 4.2	140.2	160.3	1.00
prek-head run --all-files	152.3 ± 7.3	144.3	191.7	1.03 ± 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	22.5 ± 0.4	21.5	23.2	1.01 ± 0.10
prek-head run trailing-whitespace --all-files	22.2 ± 2.1	21.1	32.3	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	28.4 ± 1.8	25.8	31.9	1.01 ± 0.10
prek-head run end-of-file-fixer --all-files	28.2 ± 2.3	24.8	32.4	1.00

prek run check-json --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-json --all-files	12.9 ± 0.5	12.1	15.1	1.05 ± 0.11
prek-head run check-json --all-files	12.3 ± 1.2	11.2	16.2	1.00

prek run check-yaml --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-yaml --all-files	11.7 ± 0.3	11.3	12.4	1.01 ± 0.04
prek-head run check-yaml --all-files	11.6 ± 0.3	11.0	12.9	1.00

prek run check-toml --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-toml --all-files	11.9 ± 0.2	11.5	12.5	1.01 ± 0.09
prek-head run check-toml --all-files	11.8 ± 1.0	10.9	15.4	1.00

prek run check-xml --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-xml --all-files	12.2 ± 0.5	11.4	13.8	1.00
prek-head run check-xml --all-files	12.2 ± 0.4	11.4	13.6	1.00 ± 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	19.0 ± 1.5	16.5	23.2	1.00
prek-head run detect-private-key --all-files	20.0 ± 2.0	16.7	26.5	1.05 ± 0.13

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	25.0 ± 1.8	22.0	27.7	1.00 ± 0.10
prek-head run fix-byte-order-marker --all-files	24.9 ± 1.7	22.2	28.1	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	5.1 ± 0.1	5.1	5.3	1.04 ± 0.03
prek-head install-hooks	4.9 ± 0.1	4.8	5.0	1.00

prek install-hooks (warm - with cache)

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base install-hooks	5.2 ± 0.1	5.1	5.4	1.09 ± 0.04
prek-head install-hooks	4.8 ± 0.1	4.7	4.9	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	51.4 ± 1.4	49.8	55.7	1.01 ± 0.04
prek-head run	50.8 ± 1.2	48.1	52.8	1.00

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

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run --files '*.json'	8.9 ± 0.3	8.4	9.7	1.03 ± 0.04
prek-head run --files '*.json'	8.7 ± 0.2	8.3	9.2	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	11.5 ± 0.5	11.0	13.0	1.03 ± 0.05
prek-head run --dry-run --all-files	11.2 ± 0.3	10.7	12.0	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	13.7 ± 0.3	13.4	14.4	1.14 ± 0.04
prek-head run check-hooks-apply --all-files	12.0 ± 0.4	11.7	13.3	1.00

✅ Performance improvement for prek run check-hooks-apply --all-files: 12.6500% faster

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

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-useless-excludes --all-files	12.2 ± 0.2	11.9	12.6	1.02 ± 0.03
prek-head run check-useless-excludes --all-files	12.0 ± 0.3	11.5	12.7	1.00

prek run identity --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run identity --all-files	11.2 ± 0.6	10.7	13.1	1.00
prek-head run identity --all-files	11.9 ± 1.2	10.7	15.1	1.06 ± 0.12

[Copilot]

Pull request overview

This PR optimizes prek run by deferring hook environment installation until after file collection and hook/file filtering, so hooks that will not run avoid creating install environments.

Changes:

• Adds lazy install resolution with an InstallCache shared by run/install/cache GC paths.
• Refactors hook execution into resolver/session helpers while preserving priority-group behavior.
• Adds integration coverage for skipped installable hooks and workspace project skips.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
crates/prek/src/cli/run/run.rs	Refactors run flow to filter before installing and introduces hook install resolution/session helpers.
crates/prek/src/cli/run/install.rs	Moves install logic into a dedicated module with caching and partitioned installs.
crates/prek/src/cli/run/mod.rs	Re-exports the new install module/function.
crates/prek/src/hook.rs	Adds hook-level install-environment eligibility.
crates/prek/src/store.rs	Removes installed hook scanning now handled by InstallCache.
crates/prek/src/cli/install.rs	Updates prepare/install command to use InstallCache.
crates/prek/src/cli/cache_gc.rs	Uses InstallCache to enumerate installed hook environments.
crates/prek/src/cli/reporter.rs	Makes install reporter cloneable and generalizes reporter root messages.
crates/prek/tests/skipped_hooks.rs	Adds regression tests for skipped installable hook environments.