feat(transport): add which_command for cross-platform executable resolution#774
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kakarot-dev wants to merge 2 commits intomodelcontextprotocol:mainfrom
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feat(transport): add which_command for cross-platform executable resolution#774kakarot-dev wants to merge 2 commits intomodelcontextprotocol:mainfrom
kakarot-dev wants to merge 2 commits intomodelcontextprotocol:mainfrom
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…lution Adds a `which_command()` helper that resolves executable paths via the `which` crate before constructing a `tokio::process::Command`. This fixes Windows failures where `.cmd` shim scripts (e.g. `npx.cmd`) are not found by `Command::new()` without a fully-qualified path. Closes modelcontextprotocol#456
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T-dependencies
DaleSeo
reviewed
Apr 1, 2026
| "transport-async-rw", | ||
| "tokio/process", | ||
| "dep:process-wrap", | ||
| "dep:which", |
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The which crate is now included for everyone using transport-child-process, even on Linux and macOS where Command::new already resolves PATH correctly. Since this is a library crate, it might be a good idea to make it a separate feature flag so users can opt in explicitly.
which-command = [
"transport-child-process",
"dep:which",
]
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Good call — moved which behind a separate which-command feature flag so it's fully opt-in. Users on Linux/macOS won't pull it in unless they need it. Thanks for the review!
| /// | ||
| /// # Example | ||
| /// ```rust,no_run | ||
| /// use rmcp::transport::child_process::{which_command, ConfigureCommandExt}; |
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These are re-exported.
Suggested change
| /// use rmcp::transport::child_process::{which_command, ConfigureCommandExt}; | |
| /// use rmcp::transport::{which_command, ConfigureCommandExt}; |
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Fixed — updated to use the re-exported path.
Address review feedback: the `which` dependency is now gated behind a separate `which-command` feature flag instead of being bundled into `transport-child-process`. Users on Linux/macOS who don't need cross-platform executable resolution no longer pull in the extra crate. Also fixes the doc example import path to use the re-exported `rmcp::transport::which_command`.
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Summary
Adds a
which_command()helper function that resolves executable paths via thewhichcrate before constructing atokio::process::Command. This fixes Windows failures where.cmdshim scripts (e.g.npx.cmd) are not found byCommand::new()without a fully-qualified path.Changes:
which_command(name) -> io::Result<Command>tochild_process.rswhichv7 as an optional dependency, gated behindtransport-child-processfeaturewhich_commandfromtransportmoduleUsage:
Closes #456