Add @ungrouped and @builtin group selectors

[j178]

Adds @ungrouped and @builtin special selectors to --group, --require-group, and --no-group.

Addresses #2616
Closes #2618

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[chatgpt-codex-connector]

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Reviewed commit: d7eb833510

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[codecov]

Codecov Report

❌ Patch coverage is 95.34884% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.97%. Comparing base (4b94cea) to head (d7eb833).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
crates/prek/src/cli/run/selector.rs	93.54%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2617   +/-   ##
=======================================
  Coverage   93.96%   93.97%           
=======================================
  Files         140      140           
  Lines       29639    29719   +80     
=======================================
+ Hits        27850    27927   +77     
- Misses       1789     1792    +3     

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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% 113.8KiB              prek <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
0.0%   0.4%  50.6KiB              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%  44.5KiB              prek prek::run::{closure#0}
0.0%   0.3%  44.1KiB              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%  37.1KiB              prek <prek::cli::RunOptions as clap_builder::derive::Args>::augment_args
0.0%   0.3%  35.5KiB              prek <prek::languages::rust::rust::Rust as prek::languages::LanguageBackend>::install::{closure#0}
0.0%   0.3%  34.0KiB              prek prek::cli::run::run::run::{closure#0}
0.0%   0.2%  29.0KiB              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%  27.5KiB        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%  27.0KiB              prek prek::archive::unpack::<fs_err::tokio::file::File, &std::path::PathBuf>::{closure#0}
4.2%  86.6%  10.8MiB                   And 20267 smaller methods. Use -n N to show more.
4.9% 100.0%  12.5MiB                   .text section size, the file size is 256.5MiB

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%   0.9% 113.5KiB              prek <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
0.0%   0.4%  50.6KiB              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%  44.6KiB              prek prek::run::{closure#0}
0.0%   0.3%  44.1KiB              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%  37.1KiB              prek <prek::cli::RunOptions as clap_builder::derive::Args>::augment_args
0.0%   0.3%  35.5KiB              prek <prek::languages::rust::rust::Rust as prek::languages::LanguageBackend>::install::{closure#0}
0.0%   0.3%  33.5KiB              prek prek::cli::run::run::run::{closure#0}
0.0%   0.2%  29.0KiB              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%  27.5KiB        aws_lc_sys aws_lc_0_44_0_edwards25519_scalarmuldouble
0.0%   0.2%  27.3KiB              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%  27.0KiB              prek prek::archive::unpack::<fs_err::tokio::file::File, &std::path::PathBuf>::{closure#0}
4.2%  86.6%  10.8MiB                   And 20271 smaller methods. Use -n N to show more.
4.9% 100.0%  12.5MiB                   .text section size, the file size is 256.9MiB

[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+31 (fad5e13 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	2.1 ± 0.1	2.0	2.5	1.00
prek-head --version	2.1 ± 0.1	2.0	3.0	1.00 ± 0.07

prek list

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base list	9.1 ± 0.2	8.6	9.8	1.00
prek-head list	9.2 ± 0.2	8.8	9.9	1.01 ± 0.04

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	2.4 ± 0.0	2.3	2.5	1.00
prek-head sample-config	2.4 ± 0.1	2.3	2.6	1.00 ± 0.03

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	37.1 ± 1.3	35.5	40.3	1.00
prek-head run --all-files	37.6 ± 1.0	35.8	38.8	1.01 ± 0.05

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

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run --all-files	37.5 ± 0.8	35.1	38.3	1.02 ± 0.03
prek-head run --all-files	36.9 ± 0.9	35.6	38.3	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	37.3 ± 1.1	35.6	40.2	1.00
prek-head run --all-files	37.5 ± 1.1	35.4	40.0	1.00 ± 0.04

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	12.7 ± 0.4	11.8	13.6	1.00
prek-head run trailing-whitespace --all-files	12.8 ± 0.4	12.0	13.7	1.01 ± 0.05

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	11.0 ± 0.5	10.3	12.2	1.01 ± 0.06
prek-head run end-of-file-fixer --all-files	11.0 ± 0.5	10.1	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	7.8 ± 0.3	7.3	8.3	1.03 ± 0.05
prek-head run check-json --all-files	7.6 ± 0.3	7.1	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	7.3	7.8	1.02 ± 0.03
prek-head run check-yaml --all-files	7.4 ± 0.1	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	7.7 ± 0.3	7.2	8.2	1.01 ± 0.05
prek-head run check-toml --all-files	7.6 ± 0.2	7.2	8.3	1.00

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	8.4	1.01 ± 0.06
prek-head run check-xml --all-files	7.5 ± 0.3	7.1	8.5	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	10.9 ± 0.9	9.9	13.7	1.01 ± 0.10
prek-head run detect-private-key --all-files	10.8 ± 0.6	10.0	12.7	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	12.7 ± 0.9	11.4	14.6	1.00
prek-head run fix-byte-order-marker --all-files	12.9 ± 0.9	11.3	14.6	1.01 ± 0.10

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 ± 0.1	4.4	4.6	1.01 ± 0.02
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	4.4 ± 0.0	4.3	4.5	1.00
prek-head install-hooks	4.4 ± 0.1	4.3	4.6	1.00 ± 0.03

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	23.8 ± 0.3	23.2	24.5	1.00
prek-head run	23.9 ± 0.4	23.3	24.6	1.00 ± 0.02

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

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run --files '*.json'	4.9 ± 0.1	4.8	5.1	1.00
prek-head run --files '*.json'	5.0 ± 0.1	4.8	5.1	1.01 ± 0.02

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 ± 0.2	6.5	6.9	1.00
prek-head run --dry-run --all-files	6.7 ± 0.1	6.5	7.0	1.00 ± 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	7.9 ± 0.1	7.8	8.1	1.00
prek-head run check-hooks-apply --all-files	8.0 ± 0.2	7.8	8.2	1.01 ± 0.02

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

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-useless-excludes --all-files	8.5 ± 0.4	7.8	9.1	1.07 ± 0.06
prek-head run check-useless-excludes --all-files	8.0 ± 0.2	7.7	8.3	1.00

prek run identity --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run identity --all-files	6.8 ± 0.2	6.6	7.1	1.00
prek-head run identity --all-files	6.9 ± 0.2	6.7	7.4	1.01 ± 0.04