move the versioning section below the library reference

.gitignore

@@ -3,3 +3,4 @@ build/
 *.egg-info/
 __pycache__/
 *.pyc
+pyproject.toml

README.md

@@ -124,6 +124,28 @@ fast `interval_ms` loop.
 
 **`to_datetime(unix_milli)`** — converts back to a local `datetime`, for logging.
 
+## Versioning and the pyproject template
+
+There is no `pyproject.toml` in this repository — it is generated from
+`pyproject.toml.tmpl`, whose version line reads `version = "{{vless .TagName}}"`.
+gitea-sidecar renders every `*.tmpl` in the source to its name minus the suffix before
+building the wheel, so a tag of `v0.1.3` publishes version `0.1.3`; `vless` strips the
+leading `v` that git wants and PEP 440 forbids. The tag is the only place a version is
+written, and the published wheel cannot disagree with the tag that produced it.
+
+Do not put a hardcoded version back into the template: the build would keep producing that
+one version, and the next tag would fail with a 409 because the package file already
+exists.
+
+**Building locally** needs the same render step, since the file the build tools look for is
+not in the repository:
+
+```bash
+sed 's/{{vless .TagName}}/0.0.0.dev0/' pyproject.toml.tmpl > pyproject.toml
+```
+
+`pyproject.toml` is gitignored, so a local copy never reaches a build.
+
 ## Error handling
 
 Every method in this library catches its own exceptions, prints a line, and returns an empty

pyproject.toml.tmpl

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "i7lib"
-version = "0.1.0"
+version = "{{vless .TagName}}"
 description = "i7 library for scripts"
 readme = "README.md"
 requires-python = ">=3.8"