fix(install): use src-layout package-dir so editable install ships a .pth

[zackees]

Summary

The per-package package-dir = {fbuild = "python/fbuild", "fbuild.api" = "python/fbuild/api"} map made setuptools' editable install emit a PEP 660 meta-path finder whose MAPPING only registered fbuild. fbuild.api resolved at runtime via importlib.machinery.PathFinder — fine for import fbuild.api, but invisible to static analyzers (ty, pyright, mypy) that walk top_level.txt / .pth files.

Downstream consumers (FastLED hit this on from fbuild.api import SerialMonitor) saw Cannot resolve imported module 'fbuild.api' even though runtime imports worked. The Stop-hook lint in FastLED failed on every bash lint after switching to an editable fbuild install.

Replace the per-package map with the canonical src-layout pattern package-dir = {"" = "python"}. Setuptools now emits a plain .pth pointing at python/, which every static analyzer handles, and the wheel-build path is unaffected.

Verification

Wheel artifact (python -m build of both states, cp310-cp310-win_amd64):

	Wheel size	Sdist size	Wheel contents
Baseline	10,454,675 B	2,316,616 B	fbuild/__init__.py, fbuild/_native.pyd, fbuild/api/__init__.py, fbuild-2.2.31.data/scripts/fbuild.exe, dist-info
This PR	10,454,675 B	2,319,427 B	byte-identical to baseline

• Wheel is byte-for-byte identical.
• Sdist is +2,811 B / +0.12% — entirely from fbuild.egg-info/ relocating to python/fbuild.egg-info/. Cosmetic.

Release path (ci/publish.py) is independent of [tool.setuptools] — it hand-rolls wheels from the hard-coded PYTHON_SHIMS_DIR = ROOT / "python". Smoke-tested: still finds the same 2 shims (fbuild/__init__.py, fbuild/api/__init__.py). Same EXTENSION_NAMES. No change.

Perf (measured against the work in #743 / #744):

• Editable reinstall (FastLED → fbuild via [tool.uv.sources]): ~8s before, ~8s after. Within noise.
• Cold install (3.7GB cargo cache nuked): ~8.9s. Dominated by mtime-skip + wheel I/O, both unchanged.
• Warm uv run python --version: 110-139ms. Within perf(uv): rebuild fbuild ~14x faster on no-source-change reinstall #743's baseline noise.
• mtime-skip in BuildWithCargo.run untouched. Dev-profile gate (perf(build): default to dev profile + rust-lld for ~5x faster Rust-edit rebuild #744) untouched. scripts= binary shipping (Ship fbuild as a raw native binary, drop the Python wrapper (cmd → fbuild.exe directly) #746) untouched.

Test plan

• python -m build produces byte-identical wheel
• python -m build produces structurally-identical sdist
• ci/publish.py::read_project_meta() + PYTHON_SHIMS_DIR.rglob('*.py') resolves correctly
• FastLED editable install: __editable__.fbuild-2.2.31.pth contains <fbuild>/python
• uv run ty check resolves both import fbuild and from fbuild.api import SerialMonitor
• uv run fbuild --version → fbuild 2.2.31
• Runtime: import fbuild.api resolves to python/fbuild/api/__init__.py
• CI green (this PR)

🤖 Generated with Claude Code

Summary by CodeRabbit

• Chores
  • Updated packaging configuration to improve how the package is exposed during development installations.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 11551a4c-45fe-487f-b870-b48fe7bfe573

📥 Commits

Reviewing files that changed from the base of the PR and between a426a0d and 513b4cd.

📒 Files selected for processing (1)

• pyproject.toml

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📝 Walkthrough

Walkthrough

pyproject.toml's [tool.setuptools.package-dir] section is changed from two explicit per-package entries (fbuild → python/fbuild, fbuild.api → python/fbuild/api) to a single root mapping ("" → python), switching to a src-layout-style discovery that covers all packages under python/.

Changes

Setuptools Package Directory Mapping

Layer / File(s)	Summary
Setuptools package-dir root mapping pyproject.toml	Replaces explicit per-package entries with "" = "python", so all packages under python/ are discovered via a single root mapping. Editable installs now emit a plain .pth pointing at python/ instead of a meta-path finder.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~5 minutes

Possibly related PRs

• FastLED/fbuild#743: Also modifies pyproject.toml's [tool.setuptools.package-dir] mapping to adjust how python/ sources are exposed during builds and editable installs.

Poem

A bunny hopped through pyproject one day,
And found two package paths blocking the way.
"One root to rule them all!" it declared,
Mapping "" to python/ — problems repaired.
Now static analyzers can follow the trail 🐇✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title directly and accurately describes the main change: switching to src-layout package-dir to make editable installs produce a .pth file instead of a meta-path finder.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/editable-install-static-analysis

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