fix(build): use an sdist allowlist so the zarr sdist stops shipping subpackages (#4261)

* fix(build): use an sdist allowlist so the zarr sdist stops shipping subpackages

The root sdist config was a blocklist naming /.github, /bench and /docs, so
every release shipped whatever else happened to sit in the repository root.
That included the whole packages/ tree — the zarr-indexing, zarr-metadata and
zarr-http-server sources, which are released as their own distributions — plus
ci/, design/, towncrier fragments and other repo furniture. 2.9M of the 1.4M
sdist was other people's packages.

Replace it with an explicit allowlist, matching what packages/zarr-indexing and
packages/zarr-metadata already do.

Including /docs also fixes a second problem: tests/test_docs.py walks docs/ and
testpaths collects docs/user-guide, so with docs/ excluded the shipped test
suite died at collection with 'Not a file or directory'. tests/test_docs.py now
runs green from an unpacked sdist (61 passed, 2 skipped), and full collection
finds 7581 tests with no errors.

Assisted-by: ClaudeCode:claude-opus-5

* docs(build): trim the sdist allowlist comment

Drop the narration of the blocklist this replaced -- that history lives in
git -- and keep only the durable rationale and the reason each entry is on
the list.

Assisted-by: ClaudeCode:claude-opus-5

Author: d-v-b

changes/4261.misc.md

@@ -0,0 +1 @@
+The contents of the `zarr` source distribution are now defined by an explicit allowlist rather than a blocklist. Previously the sdist bundled the whole `packages/` tree — `zarr-indexing`, `zarr-metadata` and `zarr-http-server`, which are released as their own distributions — along with CI configuration and other repository files. The sdist also now ships `docs/`, so the test suite it carries can be collected and run from an unpacked sdist.

pyproject.toml

@@ -2,11 +2,23 @@
 requires = ["hatchling>=1.29.0", "hatch-vcs"]
 build-backend = "hatchling.build"
 
+# An allowlist, not a blocklist: anything new — a subpackage under `packages/`, a
+# config file in the repository root — stays out of the sdist unless it is named
+# here. Beyond `src` and `tests`, the entries are what keeps the shipped test
+# suite and docs build runnable from an unpacked sdist: `tests/test_docs.py`
+# walks `docs/` and `testpaths` collects `docs/user-guide`; the pages under
+# `docs/user-guide/examples/` pull their source out of `examples/` via pymdownx
+# snippet includes; `mkdocs.yml` and `mkdocs_hooks.py` let `mkdocs build` run
+# too. `pyproject.toml`, `README.md`, `LICENSE.txt` and `.gitignore` are added by
+# hatchling itself.
 [tool.hatch.build.targets.sdist]
-exclude = [
-  "/.github",
-  "/bench",
+include = [
+  "/src",
+  "/tests",
   "/docs",
+  "/examples",
+  "/mkdocs.yml",
+  "/mkdocs_hooks.py",
 ]
 
 [project]