Retry uv pip install with an inferred Python constraint

[nikosavola]

When uv pip install fails to resolve because the venv's Python is too old for a (possibly transitive) dependency, parse the required Python version from uv's error, recreate the venv with that constraint, and retry once.

Closes #1618.

[codecov]

Codecov Report

❌ Patch coverage is 78.26087% with 30 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.31%. Comparing base (928dc5c) to head (b426e22).
⚠️ Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
crates/prek/src/languages/python/python.rs	77.77%	30 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2396      +/-   ##
==========================================
- Coverage   93.38%   93.31%   -0.08%     
==========================================
  Files         129      129              
  Lines       27637    27774     +137     
==========================================
+ Hits        25810    25917     +107     
- Misses       1827     1857      +30     

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[Copilot]

Pull request overview

This PR improves the Python hook installation flow by adding a targeted fallback when uv pip install fails due to the venv Python being too old for a (possibly transitive) dependency. It infers a minimum required Python version from uv’s resolution error output, recreates the venv using that inferred constraint, and retries dependency installation once.

Changes:

• Refactors Python dependency installation into a dedicated install_dependencies helper and adds a single-retry path on resolution failure.
• Implements infer_python_request(stderr) to extract the highest Python>=X.Y[.Z] bound from uv’s error output and converts it into a major.minor Python request.
• Adds unit tests validating that inference selects the highest bound and drops patch versions.

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[chatgpt-codex-connector]

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📦 Cargo Bloat Comparison

Binary size change: +0.34% (29.2 MiB → 29.3 MiB)

Expand for cargo-bloat output

Head Branch Results

 File  .text     Size             Crate Name
 1.1%   2.3% 332.0KiB        aws_lc_sys aws_lc_0_42_0_aes_gcm_encrypt_avx512
 1.1%   2.3% 332.0KiB        aws_lc_sys aws_lc_0_42_0_aes_gcm_decrypt_avx512
 0.2%   0.5%  65.4KiB              prek <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.2%   0.4%  55.1KiB              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>
 0.2%   0.3%  49.4KiB annotate_snippets annotate_snippets::renderer::render::render
 0.1%   0.3%  38.8KiB              prek prek::cli::run::run::run::{closure#0}
 0.1%   0.3%  37.8KiB              prek prek::run::{closure#0}
 0.1%   0.2%  34.3KiB              prek <prek::cli::RunOptions as clap_builder::derive::Args>::augment_args
 0.1%   0.2%  30.1KiB     granit_parser <granit_parser::scanner::Scanner<granit_parser::input::str::StrInput>>::fetch_more_tokens
 0.1%   0.2%  28.4KiB    cargo_metadata <&mut serde_json::de::Deserializer<serde_json::read::StrRead> as serde_core::de::Deserializer>::deserialize_struct::<<cargo_metadata::Package as serde_core::de::Deserialize>::deserialize::__Visitor>
 0.1%   0.2%  28.0KiB        aws_lc_sys aws_lc_0_42_0_edwards25519_scalarmuldouble_alt
 0.1%   0.2%  27.5KiB        aws_lc_sys aws_lc_0_42_0_edwards25519_scalarmuldouble
 0.1%   0.2%  27.2KiB              prek <<prek::config::RemoteHook 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>
 0.1%   0.2%  25.9KiB              prek prek::cli::try_repo::try_repo::{closure#0}
 0.1%   0.2%  25.4KiB              prek prek::cli::update::update::{closure#0}
 0.1%   0.2%  24.9KiB               xml <xml::reader::parser::PullParser>::dispatch_token
 0.1%   0.2%  24.5KiB              prek <prek::languages::node::installer::NodeInstaller>::install::{closure#0}
 0.1%   0.2%  24.3KiB              prek <<prek::config::LocalHook 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>
 0.1%   0.2%  24.0KiB     granit_parser <granit_parser::scanner::Scanner<serde_saphyr::de::buffered_input::ReaderInput>>::fetch_more_tokens
 0.1%   0.2%  23.7KiB              prek <<prek::config::UpdateOptions 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>
42.3%  88.4%  12.4MiB                   And 25906 smaller methods. Use -n N to show more.
47.9% 100.0%  14.0MiB                   .text section size, the file size is 29.3MiB

Base Branch Results

 File  .text     Size             Crate Name
 1.1%   2.3% 332.0KiB        aws_lc_sys aws_lc_0_42_0_aes_gcm_encrypt_avx512
 1.1%   2.3% 332.0KiB        aws_lc_sys aws_lc_0_42_0_aes_gcm_decrypt_avx512
 0.2%   0.5%  65.4KiB              prek <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.2%   0.4%  55.1KiB              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>
 0.2%   0.3%  49.4KiB annotate_snippets annotate_snippets::renderer::render::render
 0.2%   0.3%  47.0KiB              prek prek::run::{closure#0}
 0.1%   0.3%  38.4KiB              prek prek::cli::run::run::run::{closure#0}
 0.1%   0.2%  34.3KiB              prek <prek::cli::RunOptions as clap_builder::derive::Args>::augment_args
 0.1%   0.2%  30.1KiB     granit_parser <granit_parser::scanner::Scanner<granit_parser::input::str::StrInput>>::fetch_more_tokens
 0.1%   0.2%  28.0KiB        aws_lc_sys aws_lc_0_42_0_edwards25519_scalarmuldouble_alt
 0.1%   0.2%  27.5KiB        aws_lc_sys aws_lc_0_42_0_edwards25519_scalarmuldouble
 0.1%   0.2%  27.2KiB              prek <<prek::config::RemoteHook 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>
 0.1%   0.2%  26.2KiB              prek prek::cli::try_repo::try_repo::{closure#0}
 0.1%   0.2%  24.9KiB               xml <xml::reader::parser::PullParser>::dispatch_token
 0.1%   0.2%  24.6KiB              prek <prek::languages::node::installer::NodeInstaller>::install::{closure#0}
 0.1%   0.2%  24.3KiB              prek <<prek::config::LocalHook 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>
 0.1%   0.2%  24.0KiB     granit_parser <granit_parser::scanner::Scanner<serde_saphyr::de::buffered_input::ReaderInput>>::fetch_more_tokens
 0.1%   0.2%  23.7KiB              prek <<prek::config::UpdateOptions 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>
 0.1%   0.2%  22.8KiB              prek prek::archive::unzip::<fs_err::tokio::file::File, &std::path::PathBuf>::{closure#0}
 0.1%   0.2%  22.3KiB         [Unknown] Lp384_montjscalarmul_alt_p384_montjadd
42.3%  88.4%  12.4MiB                   And 25902 smaller methods. Use -n N to show more.
47.9% 100.0%  14.0MiB                   .text section size, the file size is 29.2MiB

[prek-ci-bot]

⚡️ Hyperfine Benchmarks

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

Environment

• OS: Linux 6.17.0-1020-azure
• CPU: 4 cores
• prek version: prek 0.4.10+30 (4a09cf6 2026-07-24)
• Rust version: rustc 1.97.1 (8bab26f4f 2026-07-14)
• 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	1.8 ± 0.1	1.7	2.6	1.04 ± 0.10
prek-head --version	1.7 ± 0.1	1.6	2.6	1.00

prek list

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base list	8.1 ± 0.2	7.8	8.6	1.03 ± 0.03
prek-head list	7.9 ± 0.1	7.6	8.2	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	2.7 ± 0.1	2.6	2.9	1.03 ± 0.04
prek-head validate-config .pre-commit-config.yaml	2.7 ± 0.1	2.5	2.9	1.00

prek sample-config

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base sample-config	2.1 ± 0.1	1.9	2.2	1.01 ± 0.04
prek-head sample-config	2.1 ± 0.1	1.9	2.2	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	45.5 ± 1.0	44.0	47.2	1.00
prek-head run --all-files	45.6 ± 1.2	43.9	47.6	1.00 ± 0.03

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

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run --all-files	45.5 ± 0.9	44.0	47.6	1.00 ± 0.03
prek-head run --all-files	45.4 ± 0.9	43.4	47.0	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	45.8 ± 0.6	44.7	46.9	1.00
prek-head run --all-files	46.2 ± 1.1	44.8	51.1	1.01 ± 0.03

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	14.1 ± 0.2	13.8	14.5	1.00
prek-head run trailing-whitespace --all-files	14.1 ± 0.4	13.5	15.0	1.00 ± 0.03

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	13.9 ± 0.4	13.0	14.9	1.02 ± 0.05
prek-head run end-of-file-fixer --all-files	13.7 ± 0.5	12.7	14.7	1.00

prek run check-json --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-json --all-files	5.8 ± 0.2	5.5	6.2	1.01 ± 0.05
prek-head run check-json --all-files	5.8 ± 0.2	5.5	6.3	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	5.7	6.2	1.02 ± 0.04
prek-head run check-yaml --all-files	5.8 ± 0.2	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	5.3	6.2	1.03 ± 0.05
prek-head run check-toml --all-files	5.7 ± 0.2	5.2	6.1	1.00

prek run check-xml --all-files

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run check-xml --all-files	5.7 ± 0.2	5.4	6.0	1.01 ± 0.04
prek-head run check-xml --all-files	5.6 ± 0.2	5.3	6.0	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	8.3 ± 0.5	7.4	9.9	1.05 ± 0.08
prek-head run detect-private-key --all-files	7.9 ± 0.4	7.4	8.6	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	13.7 ± 0.4	13.1	14.6	1.00
prek-head run fix-byte-order-marker --all-files	13.7 ± 0.5	12.8	14.5	1.00 ± 0.04

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	3.7	3.8	1.00
prek-head install-hooks	3.9 ± 0.2	3.7	4.1	1.04 ± 0.05

prek install-hooks (warm - with cache)

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base install-hooks	3.7 ± 0.1	3.6	3.8	1.02 ± 0.04
prek-head install-hooks	3.6 ± 0.1	3.6	3.9	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	25.8 ± 0.4	25.0	26.4	1.01 ± 0.02
prek-head run	25.7 ± 0.4	25.2	26.6	1.00

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

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
prek-base run --files '*.json'	5.9 ± 0.1	5.7	6.1	1.02 ± 0.02
prek-head run --files '*.json'	5.8 ± 0.1	5.6	6.0	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	5.3 ± 0.2	5.1	5.7	1.01 ± 0.04
prek-head run --dry-run --all-files	5.3 ± 0.1	5.1	5.4	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	8.9 ± 0.2	8.6	9.3	1.00 ± 0.03
prek-head run check-hooks-apply --all-files	8.9 ± 0.2	8.7	9.2	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 ± 0.4	8.1	9.0	1.06 ± 0.05
prek-head run check-useless-excludes --all-files	8.1 ± 0.1	7.9	8.3	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	7.6	1.00
prek-head run identity --all-files	7.5 ± 0.2	7.3	7.8	1.01 ± 0.02

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Preserve strict Python lower bounds on retry

When uv reports a strict lower bound such as Python>3.10.20, this pattern matches it but only captures the version; the retry request is then built as >=3.10.20. If the failed interpreter is exactly 3.10.20 and remains discoverable, recreating the venv can succeed with the same interpreter, so the second pip install fails again instead of selecting or downloading a Python that actually satisfies the dependency.

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