Prevent auto-update cooldown downgrades

[j178]

Closes #2051.

This prevents prek auto-update --cooldown-days from replacing a newer current rev with an older rev selected by the cooldown window. It also reports the skipped downgrade and documents the behavior.

[codecov]

Codecov Report

❌ Patch coverage is 95.85799% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.32%. Comparing base (260f2b1) to head (5da7830).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
crates/prek/src/cli/auto_update/repository.rs	94.01%	7 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           master    #2055    +/-   ##
========================================
  Coverage   92.32%   92.32%            
========================================
  Files         119      119            
  Lines       24320    24429   +109     
========================================
+ Hits        22453    22555   +102     
- Misses       1867     1874     +7     

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[prek-ci-bot]

📦 Cargo Bloat Comparison

Binary size change: -0.76% (26.3 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_39_1_aes_gcm_encrypt_avx512
 1.2%   2.6% 332.0KiB        aws_lc_sys aws_lc_0_39_1_aes_gcm_decrypt_avx512
 0.3%   0.7%  91.7KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.3%   0.6%  83.6KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.2%   0.5%  65.4KiB              prek prek::languages::<impl prek::config::Language>::install::{{closure}}
 0.2%   0.5%  60.3KiB             prek? <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.2%   0.4%  53.3KiB annotate_snippets annotate_snippets::renderer::render::render
 0.2%   0.4%  48.8KiB              prek prek::run::{{closure}}
 0.2%   0.3%  43.8KiB              prek prek::cli::run::run::run::{{closure}}
 0.1%   0.3%  32.5KiB             prek? <prek::cli::RunArgs as clap_builder::derive::Args>::augment_args
 0.1%   0.2%  32.0KiB             prek? <prek::config::_::<impl serde_core::de::Deserialize for prek::config::Config>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map
 0.1%   0.2%  28.3KiB               std core::ptr::drop_in_place<prek::languages::<impl prek::config::Language>::install::{{closure}}>
 0.1%   0.2%  28.0KiB        aws_lc_sys aws_lc_0_39_1_edwards25519_scalarmuldouble_alt
 0.1%   0.2%  27.6KiB      serde_saphyr saphyr_parser_bw::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2%  27.5KiB        aws_lc_sys aws_lc_0_39_1_edwards25519_scalarmuldouble
 0.1%   0.2%  26.4KiB              prek prek::cli::try_repo::try_repo::{{closure}}
 0.1%   0.2%  24.5KiB              prek prek::hooks::meta_hooks::MetaHooks::run::{{closure}}
 0.1%   0.2%  23.5KiB             prek? <prek::cli::Command as clap_builder::derive::FromArgMatches>::from_arg_matches_mut
 0.1%   0.2%  22.5KiB      serde_saphyr saphyr_parser_bw::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2%  22.3KiB         [Unknown] Lp384_montjscalarmul_alt_p384_montjadd
41.6%  86.3%  10.9MiB                   And 23891 smaller methods. Use -n N to show more.
48.1% 100.0%  12.6MiB                   .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_39_1_aes_gcm_encrypt_avx512
 1.2%   2.6% 332.0KiB        aws_lc_sys aws_lc_0_39_1_aes_gcm_decrypt_avx512
 0.3%   0.7%  90.9KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.3%   0.6%  83.6KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.2%   0.5%  65.4KiB              prek prek::languages::<impl prek::config::Language>::install::{{closure}}
 0.2%   0.5%  62.0KiB             prek? <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.2%   0.4%  53.3KiB annotate_snippets annotate_snippets::renderer::render::render
 0.2%   0.4%  48.8KiB              prek prek::run::{{closure}}
 0.2%   0.3%  43.8KiB              prek prek::cli::run::run::run::{{closure}}
 0.1%   0.3%  33.4KiB             prek? <prek::cli::RunArgs as clap_builder::derive::Args>::augment_args
 0.1%   0.2%  30.8KiB             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%  28.6KiB               std core::ptr::drop_in_place<prek::languages::<impl prek::config::Language>::install::{{closure}}>
 0.1%   0.2%  28.0KiB        aws_lc_sys aws_lc_0_39_1_edwards25519_scalarmuldouble_alt
 0.1%   0.2%  27.6KiB      serde_saphyr saphyr_parser_bw::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2%  27.5KiB        aws_lc_sys aws_lc_0_39_1_edwards25519_scalarmuldouble
 0.1%   0.2%  26.4KiB              prek prek::cli::try_repo::try_repo::{{closure}}
 0.1%   0.2%  24.5KiB              prek prek::hooks::meta_hooks::MetaHooks::run::{{closure}}
 0.1%   0.2%  22.5KiB      serde_saphyr saphyr_parser_bw::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
41.8%  86.5%  11.0MiB                   And 23955 smaller methods. Use -n N to show more.
48.4% 100.0%  12.7MiB                   .text section size, the file size is 26.3MiB

[prek-ci-bot]

⚡️ Hyperfine Benchmarks

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

Environment

• OS: Linux 6.17.0-1010-azure
• CPU: 4 cores
• prek version: prek 0.3.13+7 (0e91390 2026-05-06)
• 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	2.5 ± 0.1	2.4	3.4	1.03 ± 0.07
prek-head --version	2.4 ± 0.1	2.3	2.7	1.00

prek list

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base list	9.4 ± 0.2	9.1	10.2	1.00
prek-head list	9.5 ± 0.2	9.1	10.3	1.00 ± 0.04

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

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base validate-config .pre-commit-config.yaml	3.4 ± 0.1	3.3	3.5	1.00
prek-head validate-config .pre-commit-config.yaml	3.4 ± 0.1	3.3	3.8	1.01 ± 0.04

prek sample-config

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base sample-config	2.8 ± 0.1	2.6	2.9	1.00
prek-head sample-config	2.8 ± 0.1	2.6	3.1	1.02 ± 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	145.0 ± 2.7	141.4	151.1	1.00 ± 0.03
prek-head run --all-files	144.3 ± 3.4	141.0	149.4	1.00

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

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run --all-files	144.4 ± 4.0	139.6	150.7	1.01 ± 0.04
prek-head run --all-files	143.4 ± 3.6	139.4	151.7	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	144.6 ± 3.7	138.3	153.1	1.00
prek-head run --all-files	145.4 ± 3.6	139.1	152.5	1.01 ± 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	21.5 ± 1.0	20.5	24.9	1.03 ± 0.05
prek-head run trailing-whitespace --all-files	21.0 ± 0.5	20.3	22.3	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	28.3 ± 2.4	24.7	32.5	1.01 ± 0.15
prek-head run end-of-file-fixer --all-files	28.1 ± 3.3	23.6	39.9	1.00

prek run check-json --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-json --all-files	13.0 ± 0.3	12.4	13.6	1.08 ± 0.04
prek-head run check-json --all-files	12.0 ± 0.3	11.6	12.7	1.00

prek run check-yaml --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-yaml --all-files	12.3 ± 0.4	11.6	13.0	1.00 ± 0.09
prek-head run check-yaml --all-files	12.2 ± 1.0	11.4	16.7	1.00

prek run check-toml --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-toml --all-files	12.1 ± 0.3	11.6	12.8	1.00 ± 0.04
prek-head run check-toml --all-files	12.1 ± 0.3	11.6	12.8	1.00

prek run check-xml --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-xml --all-files	13.1 ± 6.2	11.6	45.9	1.06 ± 0.50
prek-head run check-xml --all-files	12.4 ± 0.4	11.5	13.0	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	18.4 ± 1.2	16.3	20.4	1.04 ± 0.10
prek-head run detect-private-key --all-files	17.7 ± 1.2	15.9	19.6	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	22.8 ± 1.7	19.7	25.1	1.01 ± 0.10
prek-head run fix-byte-order-marker --all-files	22.7 ± 1.6	20.2	25.9	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	4.9	5.0	1.00
prek-head install-hooks	4.9 ± 0.1	4.8	5.0	1.00 ± 0.02

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	1.00
prek-head install-hooks	4.9 ± 0.1	4.8	5.0	1.00 ± 0.02

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	50.7 ± 0.8	49.3	52.0	1.00 ± 0.03
prek-head run	50.6 ± 1.0	49.0	52.5	1.00

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

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run --files '*.json'	8.8 ± 0.1	8.6	9.2	1.01 ± 0.02
prek-head run --files '*.json'	8.7 ± 0.1	8.5	8.9	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	10.9 ± 0.1	10.7	11.1	1.00
prek-head run --dry-run --all-files	11.0 ± 0.2	10.8	11.5	1.00 ± 0.02

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	13.5 ± 0.1	13.3	13.8	1.00
prek-head run check-hooks-apply --all-files	13.6 ± 0.5	12.1	14.0	1.01 ± 0.04

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

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-useless-excludes --all-files	11.9 ± 0.1	11.7	12.2	1.00
prek-head run check-useless-excludes --all-files	12.0 ± 0.2	11.6	12.5	1.01 ± 0.02

prek run identity --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run identity --all-files	10.8 ± 0.1	10.7	10.9	1.00
prek-head run identity --all-files	11.2 ± 0.3	10.9	11.7	1.04 ± 0.03

[Copilot]

Pull request overview

This PR fixes an auto-update edge case where --cooldown-days could “update” a repository to an older tag than the currently pinned rev. It introduces explicit downgrade prevention (with user-facing messaging), adds regression tests, and documents the behavior in the CLI/config references.

Changes:

• Prevent cooldown-based revision selection from replacing a newer current rev with an older cooldown-eligible tag (skip + report instead).
• Add display/output plumbing to surface “skipped downgrade” events to the user.
• Update documentation and add integration/unit tests covering the downgrade-prevention behavior.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
docs/reference/configuration.md	Documents cooldown precedence and explicitly states cooldowns never downgrade; improves intra-doc links/anchors.
docs/reference/cli.md	Updates --cooldown-days help text to describe the non-downgrade behavior.
docs/configuration.md	Replaces duplicated prose with a link to the configuration reference section.
crates/prek/tests/auto_update.rs	Adds an end-to-end regression test ensuring cooldown does not downgrade the pinned rev.
crates/prek/src/cli/mod.rs	Updates clap help text for --cooldown-days to match the new behavior.
crates/prek/src/cli/auto_update/source.rs	Threads the new revision selection result (RevisionSelection) through target evaluation and preserves skip metadata.
crates/prek/src/cli/auto_update/repository.rs	Implements downgrade detection vs current pin during cooldown selection; refactors tag ordering comparator; updates tests accordingly.
crates/prek/src/cli/auto_update/mod.rs	Introduces RevisionSelection / SkippedDowngrade types and stores skipped-downgrade metadata in resolved updates.
crates/prek/src/cli/auto_update/display.rs	Adds formatting and emission of “skipped downgrade” messages and suppresses redundant verbose “up to date” output in that case.

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Reviewed commit: 1e4dfae43d

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[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated no new comments.