doc: merge news into generated changelog

CHANGELOG.md

@@ -20,24 +20,14 @@ A brief description of the categories of changes:
 * Particular sub-systems are identified using parentheses, e.g. `(bzlmod)` or
   `(docs)`.
 
-<!--
-BEGIN_UNRELEASED_TEMPLATE
-
-{#v0-0-0}
-## Unreleased
-
-[0.0.0]: https://github.com/bazel-contrib/rules_python/releases/tag/0.0.0
-
-Unreleased changes are tracked as individual files in the [news/](./news) directory.
-
-END_UNRELEASED_TEMPLATE
--->
-{#v0-0-0}
+{#unreleased}
 ## Unreleased
 
-[0.0.0]: https://github.com/bazel-contrib/rules_python/releases/tag/0.0.0
+[unreleased]: https://github.com/bazel-contrib/rules_python/releases/tag/unreleased
 
-Unreleased changes are tracked as individual files in the [news/](./news) directory.
+Unreleased changes are tracked as individual files in the [news/](./news)
+directory, or view the [latest generated
+changelog](https://rules-python.readthedocs.io/en/latest/changelog.html).
 
 {#v2-1-0}
 ## [2.1.0] - 2026-06-17

docs/BUILD.bazel

@@ -17,6 +17,7 @@ load("@sphinxdocs//sphinxdocs:readthedocs.bzl", "readthedocs_install")
 load("@sphinxdocs//sphinxdocs:sphinx.bzl", "sphinx_build_binary", "sphinx_docs")
 load("@sphinxdocs//sphinxdocs:sphinx_docs_library.bzl", "sphinx_docs_library")
 load("@sphinxdocs//sphinxdocs:sphinx_stardoc.bzl", "sphinx_stardoc", "sphinx_stardocs")
+load("//python:defs.bzl", "py_binary")
 load("//python/private:bzlmod_enabled.bzl", "BZLMOD_ENABLED")  # buildifier: disable=bzl-visibility
 load("//python/private:common_labels.bzl", "labels")  # buildifier: disable=bzl-visibility
 load("//python/uv:lock.bzl", "lock")  # buildifier: disable=bzl-visibility
@@ -37,6 +38,27 @@ _TARGET_COMPATIBLE_WITH = select({
     "//conditions:default": ["@platforms//:incompatible"],
 }) if BZLMOD_ENABLED else ["@platforms//:incompatible"]
 
+py_binary(
+    name = "merge_changelog",
+    srcs = ["merge_changelog.py"],
+    target_compatible_with = _TARGET_COMPATIBLE_WITH,
+    deps = [
+        "//tools/private/release:changelog_news",
+    ],
+)
+
+genrule(
+    name = "merged_changelog",
+    srcs = [
+        "//:CHANGELOG.md",
+        "//news:news_files",
+    ],
+    outs = ["changelog.md"],
+    cmd = "$(location :merge_changelog) --changelog $(location //:CHANGELOG.md) --news-dir news --output $@",
+    target_compatible_with = _TARGET_COMPATIBLE_WITH,
+    tools = [":merge_changelog"],
+)
+
 # See README.md for instructions. Short version:
 # * `bazel run //docs:docs.serve` in a separate terminal
 # * `ibazel build //docs:docs` to automatically rebuild docs
@@ -60,8 +82,8 @@ sphinx_docs(
         "html",
     ],
     renamed_srcs = {
-        "//:CHANGELOG.md": "changelog.md",
         "//:CONTRIBUTING.md": "contributing.md",
+        ":merged_changelog": "changelog.md",
         "@sphinxdocs//sphinxdocs/inventories:bazel_inventory": "bazel_inventory.inv",
     },
     sphinx = ":sphinx-build",

docs/merge_changelog.py

@@ -0,0 +1,38 @@
+"""A tool to merge news entries into CHANGELOG.md for documentation preview."""
+
+import argparse
+import pathlib
+
+from tools.private.release import changelog_news
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Merge news entries into CHANGELOG.md")
+    parser.add_argument(
+        "--changelog", type=pathlib.Path, required=True, help="Path to CHANGELOG.md"
+    )
+    parser.add_argument(
+        "--news-dir", type=pathlib.Path, required=True, help="Path to news directory"
+    )
+    parser.add_argument(
+        "--output",
+        type=pathlib.Path,
+        required=True,
+        help="Path to output merged changelog",
+    )
+    args = parser.parse_args()
+
+    # Call the public merge_new_into_changelog function
+    # Using deterministic date "0000-00-00" and version "0.0.0"
+    changelog_news.merge_new_into_changelog(
+        changelog_path=args.changelog,
+        output_path=args.output,
+        news_dir=args.news_dir,
+        version="unreleased",
+        release_date="0000-00-00",
+        delete_news=False,
+    )
+
+
+if __name__ == "__main__":
+    main()