Add configurable toolchain source preferences

[j178]

Closes #2612
Closes #2607

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[codecov]

Codecov Report

❌ Patch coverage is 94.78585% with 28 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.96%. Comparing base (3364fea) to head (efdde57).

Files with missing lines	Patch %	Lines
crates/prek/src/config/hook.rs	90.75%	16 Missing ⚠️
crates/prek/src/languages/python/python.rs	89.74%	4 Missing ⚠️
crates/prek/src/config/mod.rs	92.30%	2 Missing ⚠️
crates/prek/src/hook.rs	98.75%	1 Missing ⚠️
crates/prek/src/languages/deno/installer.rs	91.66%	1 Missing ⚠️
crates/prek/src/languages/mise/installer.rs	91.66%	1 Missing ⚠️
crates/prek/src/languages/ruby/installer.rs	92.85%	1 Missing ⚠️
crates/prek/src/languages/rust/installer.rs	90.90%	1 Missing ⚠️
crates/prek/src/languages/version.rs	99.18%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2613      +/-   ##
==========================================
+ Coverage   93.89%   93.96%   +0.06%     
==========================================
  Files         140      140              
  Lines       29286    29659     +373     
==========================================
+ Hits        27499    27870     +371     
- Misses       1787     1789       +2     

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[prek-ci-bot]

📦 Cargo Bloat Comparison

.text size change: +0.00% (12.5 MiB → 12.5 MiB)

Expand for cargo-bloat output

Head Branch Results

File  .text     Size             Crate Name
0.1%   2.6% 332.0KiB        aws_lc_sys aws_lc_0_44_0_aes_gcm_encrypt_avx512
0.1%   2.6% 332.0KiB        aws_lc_sys aws_lc_0_44_0_aes_gcm_decrypt_avx512
0.0%   0.9% 113.3KiB              prek <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
0.0%   0.4%  51.4KiB              prek <<prek::config::hook::HookWire as serde_core::de::Deserialize>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map::<<serde_saphyr::de::deserializer::YamlDeserializer as serde_core::de::Deserializer>::deserialize_map::MA>
0.0%   0.4%  48.7KiB annotate_snippets annotate_snippets::renderer::render::render
0.0%   0.4%  47.5KiB              prek prek::run::{closure#0}
0.0%   0.3%  44.6KiB              prek <<prek::config::Config as serde_core::de::Deserialize>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map::<<serde_saphyr::de::deserializer::YamlDeserializer as serde_core::de::Deserializer>::deserialize_map::MA>
0.0%   0.3%  36.6KiB              prek <prek::cli::RunOptions as clap_builder::derive::Args>::augment_args
0.0%   0.3%  33.8KiB              prek <prek::languages::rust::rust::Rust as prek::languages::LanguageBackend>::install::{closure#0}
0.0%   0.3%  33.6KiB              prek prek::cli::run::run::run::{closure#0}
0.0%   0.2%  28.6KiB      serde_saphyr <granit_parser::scanner::Scanner<granit_parser::input::str::StrInput>>::fetch_more_tokens
0.0%   0.2%  28.4KiB              prek prek::archive::unpack::<fs_err::tokio::file::File, &std::path::PathBuf>::{closure#0}
0.0%   0.2%  28.0KiB        aws_lc_sys aws_lc_0_44_0_edwards25519_scalarmuldouble_alt
0.0%   0.2%  27.8KiB      serde_saphyr <granit_parser::scanner::Scanner<granit_parser::input::str::StrInput>>::fetch_more_tokens
0.0%   0.2%  27.5KiB        aws_lc_sys aws_lc_0_44_0_edwards25519_scalarmuldouble
0.0%   0.2%  27.4KiB              toml <toml::de::deserializer::value::ValueDeserializer as serde_core::de::Deserializer>::deserialize_any::<<prek::config::hook::HookWire as serde_core::de::Deserialize>::deserialize::__Visitor>
0.0%   0.2%  27.0KiB              prek prek::archive::unpack::<fs_err::tokio::file::File, &std::path::PathBuf>::{closure#0}
0.0%   0.2%  27.0KiB              prek prek::archive::unpack::<fs_err::tokio::file::File, &std::path::PathBuf>::{closure#0}
0.0%   0.2%  27.0KiB              prek prek::archive::unpack::<fs_err::tokio::file::File, &std::path::PathBuf>::{closure#0}
0.0%   0.2%  26.9KiB              prek prek::archive::unpack::<fs_err::tokio::file::File, &std::path::PathBuf>::{closure#0}
4.2%  86.6%  10.8MiB                   And 20313 smaller methods. Use -n N to show more.
4.9% 100.0%  12.5MiB                   .text section size, the file size is 256.6MiB

Base Branch Results

File  .text     Size             Crate Name
0.1%   2.6% 332.0KiB        aws_lc_sys aws_lc_0_44_0_aes_gcm_encrypt_avx512
0.1%   2.6% 332.0KiB        aws_lc_sys aws_lc_0_44_0_aes_gcm_decrypt_avx512
0.0%   0.7%  84.2KiB              prek <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
0.0%   0.4%  49.3KiB              prek <<prek::config::hook::HookWire as serde_core::de::Deserialize>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map::<<serde_saphyr::de::deserializer::YamlDeserializer as serde_core::de::Deserializer>::deserialize_map::MA>
0.0%   0.4%  48.7KiB annotate_snippets annotate_snippets::renderer::render::render
0.0%   0.3%  44.4KiB              prek <<prek::config::Config as serde_core::de::Deserialize>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map::<<serde_saphyr::de::deserializer::YamlDeserializer as serde_core::de::Deserializer>::deserialize_map::MA>
0.0%   0.3%  35.2KiB              prek prek::cli::run::run::run::{closure#0}
0.0%   0.3%  35.1KiB              prek prek::run::{closure#0}
0.0%   0.2%  29.4KiB              prek prek::archive::unpack::<fs_err::tokio::file::File, &std::path::PathBuf>::{closure#0}
0.0%   0.2%  28.6KiB      serde_saphyr <granit_parser::scanner::Scanner<granit_parser::input::str::StrInput>>::fetch_more_tokens
0.0%   0.2%  28.0KiB        aws_lc_sys aws_lc_0_44_0_edwards25519_scalarmuldouble_alt
0.0%   0.2%  27.8KiB      serde_saphyr <granit_parser::scanner::Scanner<granit_parser::input::str::StrInput>>::fetch_more_tokens
0.0%   0.2%  27.6KiB              toml <toml::de::deserializer::value::ValueDeserializer as serde_core::de::Deserializer>::deserialize_any::<<prek::config::hook::HookWire as serde_core::de::Deserialize>::deserialize::__Visitor>
0.0%   0.2%  27.5KiB        aws_lc_sys aws_lc_0_44_0_edwards25519_scalarmuldouble
0.0%   0.2%  27.2KiB              prek <prek::languages::deno::installer::DenoInstaller>::install::{closure#0}
0.0%   0.2%  27.0KiB              prek prek::archive::unpack::<fs_err::tokio::file::File, &std::path::PathBuf>::{closure#0}
0.0%   0.2%  27.0KiB              prek prek::archive::unpack::<fs_err::tokio::file::File, &std::path::PathBuf>::{closure#0}
0.0%   0.2%  27.0KiB              prek prek::archive::unpack::<fs_err::tokio::file::File, &std::path::PathBuf>::{closure#0}
0.0%   0.2%  26.9KiB              prek prek::archive::unpack::<fs_err::tokio::file::File, &std::path::PathBuf>::{closure#0}
0.0%   0.2%  26.9KiB              prek prek::archive::unpack::<fs_err::tokio::file::File, &std::path::PathBuf>::{closure#0}
4.2%  87.0%  10.8MiB                   And 20261 smaller methods. Use -n N to show more.
4.9% 100.0%  12.5MiB                   .text section size, the file size is 256.5MiB

[prek-ci-bot]

⚡️ Hyperfine Benchmarks

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

Environment

• OS: Linux 6.17.0-1022-azure
• CPU: 4 cores
• prek version: prek 0.4.14+29 (916011a 2026-08-26)
• Rust version: rustc 1.98.0 (88d9e12ae 2026-08-18)
• 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	2.4 ± 0.1	2.3	3.2	1.05 ± 0.07
prek-head --version	2.3 ± 0.1	2.2	2.6	1.00

prek list

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base list	9.5 ± 0.3	9.2	11.2	1.01 ± 0.06
prek-head list	9.5 ± 0.5	9.0	11.7	1.00

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

⏭️ Skipped: .pre-commit-config.yaml not found

prek sample-config

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base sample-config	2.7 ± 0.1	2.6	2.9	1.04 ± 0.04
prek-head sample-config	2.6 ± 0.0	2.6	2.7	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	38.4 ± 0.8	37.3	39.6	1.01 ± 0.04
prek-head run --all-files	37.9 ± 1.2	36.4	39.7	1.00

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

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run --all-files	37.7 ± 1.5	35.4	41.0	1.00
prek-head run --all-files	38.4 ± 1.7	36.4	42.6	1.02 ± 0.06

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	38.1 ± 1.5	34.7	42.4	1.03 ± 0.05
prek-head run --all-files	37.1 ± 1.2	34.4	41.5	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	12.8 ± 0.3	12.3	13.8	1.02 ± 0.03
prek-head run trailing-whitespace --all-files	12.6 ± 0.3	12.0	13.2	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	11.4 ± 0.4	10.6	12.0	1.01 ± 0.05
prek-head run end-of-file-fixer --all-files	11.3 ± 0.4	10.5	12.1	1.00

prek run check-json --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-json --all-files	8.3 ± 0.3	7.8	8.9	1.03 ± 0.05
prek-head run check-json --all-files	8.0 ± 0.2	7.6	8.5	1.00

prek run check-yaml --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-yaml --all-files	8.0 ± 0.2	7.7	8.9	1.03 ± 0.04
prek-head run check-yaml --all-files	7.8 ± 0.2	7.5	8.5	1.00

prek run check-toml --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-toml --all-files	8.1 ± 0.3	7.7	8.6	1.03 ± 0.04
prek-head run check-toml --all-files	7.8 ± 0.2	7.5	8.2	1.00

prek run check-xml --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-xml --all-files	8.2 ± 0.3	7.7	9.2	1.04 ± 0.06
prek-head run check-xml --all-files	7.9 ± 0.3	7.5	8.8	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	11.8 ± 0.7	11.0	13.8	1.00 ± 0.08
prek-head run detect-private-key --all-files	11.7 ± 0.6	10.9	13.6	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	13.3 ± 0.9	11.7	14.9	1.03 ± 0.09
prek-head run fix-byte-order-marker --all-files	12.9 ± 0.8	11.5	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	4.9 ± 0.1	4.8	5.0	1.04 ± 0.02
prek-head install-hooks	4.7 ± 0.1	4.6	4.8	1.00

prek install-hooks (warm - with cache)

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base install-hooks	4.9 ± 0.1	4.8	5.0	1.02 ± 0.01
prek-head install-hooks	4.8 ± 0.0	4.7	4.8	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	25.3 ± 0.3	24.9	25.9	1.02 ± 0.01
prek-head run	24.8 ± 0.2	24.5	25.3	1.00

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

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run --files '*.json'	5.5 ± 0.1	5.4	5.6	1.04 ± 0.02
prek-head run --files '*.json'	5.3 ± 0.1	5.2	5.4	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	7.3 ± 0.1	7.2	7.4	1.01 ± 0.01
prek-head run --dry-run --all-files	7.2 ± 0.1	7.1	7.3	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	8.7 ± 0.1	8.6	8.8	1.03 ± 0.01
prek-head run check-hooks-apply --all-files	8.4 ± 0.1	8.3	8.6	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	8.6 ± 0.1	8.4	8.7	1.00
prek-head run check-useless-excludes --all-files	8.6 ± 0.2	8.3	9.0	1.00 ± 0.03

prek run identity --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run identity --all-files	7.5 ± 0.1	7.4	7.8	1.01 ± 0.02
prek-head run identity --all-files	7.5 ± 0.1	7.3	7.6	1.00

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