diff --git a/.github/workflows/changeset-release-pr.test.mjs b/.github/workflows/changeset-release-pr.test.mjs
index 8887fc5..f044830 100644
--- a/.github/workflows/changeset-release-pr.test.mjs
+++ b/.github/workflows/changeset-release-pr.test.mjs
@@ -13,6 +13,13 @@ const indexOf = (text) => {
   return index;
 };
 
+test("version PR mutations use latest-run branch concurrency", () => {
+  assert.match(
+    workflow,
+    /concurrency:\n {6}group: changeset-release-pr-\$\{\{ github\.ref \}\}\n {6}cancel-in-progress: true/,
+  );
+});
+
 test("Rust Wasm preparation is explicit and disabled by default", () => {
   const input = workflow.match(
     / {6}prepare-rust-wasm:\n[\s\S]+?(?= {4}secrets:)/,
@@ -50,3 +57,45 @@ test("tool installation precedes the write-capable release credential", () => {
   const token = indexOf("name: Mint version PR token");
   assert.ok(preparation < token);
 });
+
+test("stale source revisions cannot mint credentials or mutate release PRs", () => {
+  const freshness = indexOf("name: Check release source is current");
+  const token = indexOf("name: Mint version PR token");
+  const release = indexOf("name: Create or update version packages PR");
+
+  assert.ok(freshness < token);
+  assert.ok(freshness < release);
+  assert.match(workflow, /GH_TOKEN: \$\{\{ github\.token \}\}/);
+  assert.match(
+    workflow,
+    /git\/ref\/heads\/\$GITHUB_REF_NAME[\s\S]+?if \[\[ "\$current_sha" == "\$GITHUB_SHA" \]\]/,
+  );
+  assert.match(
+    workflow,
+    /if: steps\.source\.outputs\.current == 'true'\n {8}name: Mint version PR token/,
+  );
+  assert.match(
+    workflow,
+    /if: steps\.source\.outputs\.current == 'true'\n {8}name: Create or update version packages PR/,
+  );
+});
+
+test("a current no-op run removes the stale release PR and branch", () => {
+  const cleanup = workflow.match(
+    / {6}- if: >-\n {10}steps\.source\.outputs\.current == 'true'[\s\S]+?(?=\n {6}- |\n\S|$)/,
+  )?.[0];
+
+  assert.ok(cleanup, "missing stale release cleanup step");
+  assert.match(
+    cleanup,
+    /steps\.changesets\.outputs\.pullRequestNumber == ''/,
+  );
+  assert.match(cleanup, /name: Remove stale version packages PR/);
+  assert.match(cleanup, /current_sha="\$\(\n {12}gh api/);
+  assert.match(cleanup, /if \[\[ "\$current_sha" != "\$GITHUB_SHA" \]\]/);
+  assert.match(cleanup, /-f base="\$BASE_BRANCH"/);
+  assert.match(cleanup, /-f head="\$owner:\$RELEASE_BRANCH"/);
+  assert.match(cleanup, /-f per_page=1/);
+  assert.match(cleanup, /-f state=closed/);
+  assert.match(cleanup, /git\/refs\/heads\/\$RELEASE_BRANCH/);
+});
diff --git a/.github/workflows/changeset-release-pr.yml b/.github/workflows/changeset-release-pr.yml
index 577a79e..77a89d5 100644
--- a/.github/workflows/changeset-release-pr.yml
+++ b/.github/workflows/changeset-release-pr.yml
@@ -58,6 +58,9 @@ jobs:
     name: Maintain version packages PR
     runs-on: ubuntu-latest
     timeout-minutes: 15
+    concurrency:
+      group: changeset-release-pr-${{ github.ref }}
+      cancel-in-progress: true
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
@@ -135,8 +138,29 @@ jobs:
           chmod 0700 "$version_command"
           printf 'path=%s\n' "$version_command" >> "$GITHUB_OUTPUT"
 
+      - name: Check release source is current
+        id: source
+        shell: bash
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          set -euo pipefail
+          current_sha="$(
+            gh api \
+              "repos/$GITHUB_REPOSITORY/git/ref/heads/$GITHUB_REF_NAME" \
+              --jq '.object.sha'
+          )"
+          if [[ "$current_sha" == "$GITHUB_SHA" ]]; then
+            echo "current=true" >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+
+          echo "current=false" >> "$GITHUB_OUTPUT"
+          echo "::notice::Skipping version PR update because $GITHUB_SHA is no longer the head of $GITHUB_REF_NAME."
+
       # Install hooks run before a write-capable credential exists in the job.
-      - name: Mint version PR token
+      - if: steps.source.outputs.current == 'true'
+        name: Mint version PR token
         id: app-token
         uses: actions/create-github-app-token@bcd2ba49218906704ab6c1aa796996da409d3eb1 # v3.2.0
         with:
@@ -147,7 +171,9 @@ jobs:
           permission-contents: write
           permission-pull-requests: write
 
-      - name: Create or update version packages PR
+      - if: steps.source.outputs.current == 'true'
+        name: Create or update version packages PR
+        id: changesets
         uses: changesets/action@a45c4d594aa4e2c509dc14a9f2b3b67ba3780d0d # v1.9.0
         with:
           version: bash ${{ steps.version-command.outputs.path }}
@@ -159,3 +185,54 @@ jobs:
           CARGO_SYNC_SCRIPT: ${{ steps.cargo-sync.outputs.script }}
           GITHUB_TOKEN: ${{ steps.app-token.outputs.token }}
           SYNC_CARGO_INHERITED_LOCK: ${{ inputs.sync-cargo-inherited-lock }}
+
+      - if: >-
+          steps.source.outputs.current == 'true' &&
+          steps.changesets.outputs.pullRequestNumber == ''
+        name: Remove stale version packages PR
+        shell: bash
+        env:
+          BASE_BRANCH: ${{ github.ref_name }}
+          GH_TOKEN: ${{ steps.app-token.outputs.token }}
+          RELEASE_BRANCH: changeset-release/${{ github.ref_name }}
+        run: |
+          set -euo pipefail
+          current_sha="$(
+            gh api \
+              "repos/$GITHUB_REPOSITORY/git/ref/heads/$BASE_BRANCH" \
+              --jq '.object.sha'
+          )"
+          if [[ "$current_sha" != "$GITHUB_SHA" ]]; then
+            echo "::notice::Skipping stale version PR cleanup because $GITHUB_SHA is no longer the head of $BASE_BRANCH."
+            exit 0
+          fi
+
+          owner="${GITHUB_REPOSITORY%%/*}"
+          pr_number="$(
+            gh api \
+              --method GET \
+              "repos/$GITHUB_REPOSITORY/pulls" \
+              -f base="$BASE_BRANCH" \
+              -f head="$owner:$RELEASE_BRANCH" \
+              -f per_page=1 \
+              -f state=open \
+              --jq '.[0].number // empty'
+          )"
+          if [[ -n "$pr_number" ]]; then
+            gh api \
+              --method PATCH \
+              "repos/$GITHUB_REPOSITORY/pulls/$pr_number" \
+              -f state=closed \
+              --silent
+            echo "::notice::Closed stale version PR #$pr_number."
+          fi
+
+          if gh api \
+            "repos/$GITHUB_REPOSITORY/git/ref/heads/$RELEASE_BRANCH" \
+            --silent >/dev/null 2>&1; then
+            gh api \
+              --method DELETE \
+              "repos/$GITHUB_REPOSITORY/git/refs/heads/$RELEASE_BRANCH" \
+              --silent
+            echo "::notice::Deleted stale branch $RELEASE_BRANCH."
+          fi
diff --git a/README.md b/README.md
index ecd7aaf..97d83f1 100644
--- a/README.md
+++ b/README.md
@@ -252,6 +252,13 @@ jobs:
 ```
 
 The caller must provide `changeset`, `changeset:version`, and a `.changeset/config.json`.
+The shared workflow serializes each target branch with latest-run concurrency and
+skips write-capable steps when its trigger commit is no longer the branch head. A
+current no-op run closes any stale version PR and deletes its generated branch, so
+interrupted runs converge without a duplicate release PR. Callers may use matching
+workflow-level concurrency to cancel obsolete setup work before the reusable job
+starts.
+
 For hybrid repositories, `changeset:version` must synchronize the selected package
 version into every npm, Cargo manifest, Python, and central `VERSION` surface. With
 `sync-cargo-inherited-lock` enabled, the shared workflow validates the incoming