fix(launcher): force uv to use managed Python (avoids macOS Xcode prompt)#322
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On macOS, uv's default --python-preference ("managed") still falls back to a
system/framework CPython when one matches. The python.org framework build is not
relocatable, so building the tool venv from it makes uv rewrite Mach-O load
paths with install_name_tool, which triggers the Xcode Command Line Tools
install dialog during first-run setup.
Set UV_PYTHON_PREFERENCE=only-managed in the launcher's uvEnv() so every uv call
(python install, tool install, GPU reinstall) uses uv's relocatable managed
builds and never the framework Python. The launcher already pins/installs a
managed 3.12; this just closes the gap where tool install could still pick up
the framework interpreter. Add a regression test for the env.
Fold the same flags into the documented PyPI/uv recipe across the docs and
READMEs (--python 3.12 --python-preference only-managed) so the CLI path avoids
the prompt too.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Problem
When first-run setup runs on macOS,
uv tool installcan trigger an Xcode"install command-line developer tools" dialog — an annoying interruption for
non-technical users the signed launcher is meant to serve.
Root cause
uv's default
--python-preferenceismanaged, which prefers a managedinterpreter but falls back to a system/framework CPython if it finds a
matching version. On macOS that's the non-relocatable python.org build at
/Library/Frameworks/Python.framework/.... Building the tool venv from it makesuv rewrite the copied executable's Mach-O load paths with
install_name_tool(part of the Xcode CLT) — which pops the install dialog when the CLT aren't
present. uv's managed (python-build-standalone) builds are relocatable, so they
never invoke
install_name_tool.Fix
Set
UV_PYTHON_PREFERENCE=only-managedin the launcher'suvEnv()— the singleplace that configures every
uvinvocation, sopython install,tool install,and the GPU-reinstall path are all consistent. The launcher already pins 3.12
and runs
uv python install 3.12first; this just closes the gap wheretool installcould still bind to the framework interpreter.Also folded the same flags (
--python 3.12 --python-preference only-managed)into the documented PyPI/
uvrecipe across the docs and READMEs, since themanual CLI path hit the same prompt.
Tests
TestUVEnvForcesManagedPythonasserts the env carriesonly-managed.go build,go vet,go test,gofmt -lall clean.🤖 Generated with Claude Code