ci: validate changelog fragment filenames (#5212)

* ci: validate changelog fragment filenames

Add a workflow step that rejects fragments whose basename doesn't match
<PR_NUMBER>.<type> (where type is one of added, changed, deprecated,
removed, fixed). This catches typos in either the PR number or the
fragment type before they produce a misleading PR link in the rendered
changelog. towncrier check verifies a fragment exists; it doesn't
enforce naming.

Also note in the do-not-edit comment of the root CHANGELOG.md that the
existing static "## Unreleased" entries must be folded into the first
towncrier-built release manually — towncrier inserts new release blocks
above that section without merging.

Assisted-by: Claude Opus 4.7 (1M context)

* Update CHANGELOG.md

* Update pyproject.toml

---------

Co-authored-by: Riccardo Magliocchetti <riccardo.magliocchetti@gmail.com>

Author: MikeGoldsmith

.github/workflows/changelog.yml

@@ -56,5 +56,30 @@ jobs:
             false
           fi
 
+      - name: Validate fragment filenames
+        env:
+          PR_NUMBER: ${{ github.event.pull_request.number }}
+        run: |
+          fragments=$(git diff --diff-filter=A --name-only origin/${{ github.base_ref }} -- '.changelog/*' | grep -v '/\.gitignore$' || true)
+          [ -z "$fragments" ] && exit 0
+          invalid=()
+          while IFS= read -r f; do
+            base=$(basename "$f")
+            if [[ ! "$base" =~ ^([0-9]+)\.(added|changed|deprecated|removed|fixed)$ ]]; then
+              invalid+=("$f (expected <PR_NUMBER>.<type>; type one of added, changed, deprecated, removed, fixed)")
+              continue
+            fi
+            if [[ "${BASH_REMATCH[1]}" != "${PR_NUMBER}" ]]; then
+              invalid+=("$f (PR number ${BASH_REMATCH[1]} does not match this PR's number ${PR_NUMBER})")
+            fi
+          done <<< "$fragments"
+          if (( ${#invalid[@]} > 0 )); then
+            echo "Invalid changelog fragment(s):"
+            for msg in "${invalid[@]}"; do
+              echo "  $msg"
+            done
+            exit 1
+          fi
+
       - name: Preview changelog
         run: towncrier build --draft --version Unreleased

pyproject.toml

@@ -174,6 +174,7 @@ issue_format = "[#{issue}](https://github.com/open-telemetry/opentelemetry-pytho
 wrap = true # wrap fragments to 79 char line length
 issue_pattern = "^(\\d+)" # only PR numbers as fragment prefix (e.g. 1234.fixed)
 
+# NOTE: remember to update the changelog workflow if these types change 
 [[tool.towncrier.type]]
 directory = "added"
 name = "Added"