fix(wasm): avoid panic in split_paths on wasm

[reubeno]

std::env::split_paths panics on some WASM platforms. For now, let's route calls to it through the sys module and provide an alternate implementation for some targets.

[github-actions]

Test Results

    3 files     32 suites   15m 34s ⏱️
2 041 tests 2 041 ✅ 0 💤 0 ❌
6 094 runs  6 094 ✅ 0 💤 0 ❌

Results for commit 3a9790c.

[github-actions]

Public API changes for crate: brush-core

Added items

+pub fn brush_core::sys::fs::split_paths<T: core::convert::AsRef<std::ffi::os_str::OsStr> + ?core::marker::Sized>(s: &T) -> std::env::SplitPaths<'_>

Performance Benchmark Report

Benchmark name	Baseline (μs)	Test/PR (μs)	Delta (μs)	Delta %
clone_shell_object	17.05 μs	17.22 μs	0.17 μs	🟠 +1.01%
eval_arithmetic	0.15 μs	0.15 μs	0.00 μs	⚪ Unchanged
expand_one_string	1.55 μs	1.54 μs	-0.01 μs	⚪ Unchanged
for_loop	27.05 μs	26.94 μs	-0.11 μs	⚪ Unchanged
full_peg_complex	57.95 μs	56.68 μs	-1.27 μs	🟢 -2.19%
full_peg_for_loop	6.24 μs	6.16 μs	-0.08 μs	🟢 -1.36%
full_peg_nested_expansions	16.88 μs	16.44 μs	-0.44 μs	🟢 -2.59%
full_peg_pipeline	4.38 μs	4.24 μs	-0.14 μs	🟢 -3.22%
full_peg_simple	1.84 μs	1.82 μs	-0.01 μs	⚪ Unchanged
function_call	2.94 μs	2.99 μs	0.05 μs	⚪ Unchanged
instantiate_shell	55.58 μs	55.91 μs	0.34 μs	⚪ Unchanged
instantiate_shell_with_init_scripts	26915.73 μs	27064.30 μs	148.57 μs	⚪ Unchanged
parse_peg_bash_completion	2121.66 μs	2065.32 μs	-56.34 μs	🟢 -2.66%
parse_peg_complex	20.55 μs	20.05 μs	-0.49 μs	🟢 -2.39%
parse_peg_for_loop	2.07 μs	2.01 μs	-0.06 μs	🟢 -2.99%
parse_peg_pipeline	2.32 μs	2.09 μs	-0.23 μs	🟢 -10.00%
parse_peg_simple	1.14 μs	1.12 μs	-0.03 μs	🟢 -2.36%
run_echo_builtin_command	18.22 μs	18.50 μs	0.28 μs	⚪ Unchanged
tokenize_sample_script	3.50 μs	3.39 μs	-0.11 μs	🟢 -3.23%

Code Coverage Report: Only Changed Files listed

Package	Base Coverage	New Coverage	Difference
brush-core/src/sys/unix/fs.rs	🟠 60.19%	🟠 61.32%	🟢 1.13%
Overall Coverage	🟢 74.33%	🟢 74.33%	⚪ 0%

Minimum allowed coverage is 70%, this run produced 74.33%

Test Summary: bash-completion test suite

Outcome	Count	Percentage
✅ Pass	1583	75.06
❗️ Error	17	0.81
❌ Fail	155	7.35
⏩ Skip	339	16.07
❎ Expected Fail	13	0.62
✔️ Unexpected Pass	2	0.09
📊 Total	2109	100.00

[Copilot]

Pull request overview

This PR mitigates a runtime panic on some WASM targets by routing PATH splitting through brush-core’s platform abstraction layer (crate::sys) and providing a WASM-safe fallback implementation.

Changes:

• Introduces crate::sys::fs::split_paths with platform-specific implementations (Unix/Windows delegate to std::env::split_paths, WASM uses a : split).
• Updates shell PATH searching to use crate::sys::fs::split_paths instead of calling std::env::split_paths directly.
• Switches Windows/WASM platform modules to provide a real fs module rather than re-exporting the stub module directly.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
brush-core/src/sys/windows/fs.rs	Adds Windows split_paths wrapper delegating to std::env::split_paths.
brush-core/src/sys/windows.rs	Uses a concrete fs module so split_paths can be provided on Windows.
brush-core/src/sys/wasm/mod.rs	Uses a concrete fs module so split_paths can be provided on WASM.
brush-core/src/sys/wasm/fs.rs	Adds WASM split_paths implementation (currently allocates and string-converts).
brush-core/src/sys/unix/fs.rs	Adds Unix split_paths wrapper and routes existing code through it.
brush-core/src/shell/fs.rs	Switches PATH searching to use crate::sys::fs::split_paths.