fix(ci): gate workflow_run publishing to same-repo tag pushes

The publish and docker workflows trigger on workflow_run of CI, which
fires for every CI completion — including CI runs for pull requests
from forks — and always executes with this repo's secrets, tokens, and
the pypi environment. The only gate was CI success, so fork-PR CI runs
spawned publish jobs in the upstream context; actions/checkout v7's
fork-checkout refusal was the only thing that stopped one on 2026-06-30.
A fork PR whose head is an upstream-tagged commit would have passed the
tag check and reached the upload with valid OIDC.

Both workflows now require the triggering CI run to be a push event,
from this repository, with head_branch starting with 'v' — CI's push
trigger only matches main/stable/* branches and v* tags, so that is
necessarily a tag run (verified: tag-push runs report the tag name as
head_branch). Checkouts no longer persist the token while the tree's
build backend executes, and publishes are no longer cancellable
mid-upload (a half-uploaded release cannot be re-run cleanly because
PyPI rejects duplicate files).

vendor-js hardening in the same pass: gate on the immutable PR author
instead of github.actor, require a same-repo head before pushing to the
PR branch with contents:write, and pass github.head_ref through env
instead of interpolating it into the script body.

.github/workflows/docker-publish.yml

@@ -7,7 +7,9 @@ on:
 
 concurrency:
   group: docker-${{ github.event.workflow_run.head_sha }}
-  cancel-in-progress: true
+  # Never cancel mid-push: an interrupted multi-tag push can leave the
+  # registry with a partial tag set (e.g. :latest moved, :stable not).
+  cancel-in-progress: false
 
 permissions:
   contents: read
@@ -19,15 +21,24 @@ env:
 
 jobs:
   docker:
+    # Same gate as publish.yml: workflow_run fires for every CI completion
+    # (including fork and same-repo PR runs) with this repo's token and
+    # packages:write.  Only same-repo tag pushes may publish images; CI's
+    # push trigger matches main/stable/* and v* tags, so a head_branch
+    # starting with "v" is necessarily a tag run.
     if: >-
       github.event.workflow_run.conclusion == 'success' &&
-      github.event.workflow_run.head_repository.full_name == github.repository
+      github.event.workflow_run.event == 'push' &&
+      github.event.workflow_run.head_repository.full_name == github.repository &&
+      startsWith(github.event.workflow_run.head_branch, 'v')
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
         with:
           ref: ${{ github.event.workflow_run.head_sha }}
           fetch-depth: 0
+          # The docker build only reads the tree; keep the token out of it.
+          persist-credentials: false
 
       - name: Resolve release tag
         id: tag

.github/workflows/publish.yml

@@ -7,7 +7,9 @@ on:
 
 concurrency:
   group: publish-${{ github.event.workflow_run.head_sha }}
-  cancel-in-progress: true
+  # Never cancel a publish mid-upload: a half-uploaded release (sdist up,
+  # wheel missing) cannot be re-run cleanly because PyPI rejects duplicates.
+  cancel-in-progress: false
 
 permissions:
   contents: write
@@ -15,7 +17,16 @@ permissions:
 
 jobs:
   publish:
-    if: github.event.workflow_run.conclusion == 'success'
+    # workflow_run fires for EVERY CI completion — including CI runs for
+    # pull_requests from forks — and always executes here with this repo's
+    # secrets, tokens, and the pypi environment.  Gate to same-repo tag
+    # pushes only: CI's push trigger matches branches main/stable/* and
+    # tags v*, so a head_branch starting with "v" is necessarily a tag run.
+    if: >-
+      github.event.workflow_run.conclusion == 'success' &&
+      github.event.workflow_run.event == 'push' &&
+      github.event.workflow_run.head_repository.full_name == github.repository &&
+      startsWith(github.event.workflow_run.head_branch, 'v')
     runs-on: ubuntu-latest
     environment: pypi
     steps:
@@ -23,6 +34,9 @@ jobs:
         with:
           ref: ${{ github.event.workflow_run.head_sha }}
           fetch-depth: 0
+          # python -m build executes the tree's build backend; don't leave
+          # the contents:write token sitting in .git/config while it runs.
+          persist-credentials: false
 
       - name: Resolve release tag
         id: tag

.github/workflows/vendor-js.yml

@@ -25,18 +25,30 @@ permissions:
 
 jobs:
   vendor-js:
-    if: github.actor == 'renovate[bot]' || github.event_name == 'workflow_dispatch'
+    # Same-repo PRs only: this job checks out the PR head and pushes to it
+    # with contents:write, so it must never act on a fork's branch.
+    # Gate on the PR author (immutable), not github.actor (names whoever
+    # caused the latest event, which can be someone else re-running it).
+    if: >-
+      (github.event_name == 'pull_request' &&
+       github.event.pull_request.user.login == 'renovate[bot]' &&
+       github.event.pull_request.head.repo.full_name == github.repository) ||
+      github.event_name == 'workflow_dispatch'
     runs-on: ubuntu-latest
     steps:
       - name: Resolve PR head ref
         id: ref
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          # Branch names may contain shell metacharacters; pass via env,
+          # never interpolate ${{ }} into the script body.
+          HEAD_REF: ${{ github.head_ref }}
+          PR_NUMBER: ${{ inputs.pr_number }}
         run: |
-          if [[ "${{ github.event_name }}" == "workflow_dispatch" ]]; then
-            ref=$(gh pr view "${{ inputs.pr_number }}" --repo "${{ github.repository }}" --json headRefName -q .headRefName)
+          if [[ "$GITHUB_EVENT_NAME" == "workflow_dispatch" ]]; then
+            ref=$(gh pr view "$PR_NUMBER" --repo "$GITHUB_REPOSITORY" --json headRefName -q .headRefName)
           else
-            ref="${{ github.head_ref }}"
+            ref="$HEAD_REF"
           fi
           echo "head_ref=${ref}" >> "$GITHUB_OUTPUT"