diff --git a/.github/workflows/check-commit-messages.yml b/.github/workflows/check-commit-messages.yml
index 5996a30986..e451bc8c5c 100644
--- a/.github/workflows/check-commit-messages.yml
+++ b/.github/workflows/check-commit-messages.yml
@@ -9,6 +9,8 @@ on:
 
 permissions:
   contents: read
+  discussions: read
+  issues: read
   statuses: write
 
 concurrency:
@@ -19,44 +21,18 @@ jobs:
   closes-issue-or-discussion:
     runs-on: ubuntu-slim
     steps:
-      - name: Check for 'Closes \#' in commit messages
+      - name: Checkout code
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          persist-credentials: false
+          show-progress: false
+
+      - name: Check for closing keywords that would close a Discussion
         uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9.0.0
         with:
           script: |
-            // Co-authored-by: Claude Sonnet 4.5 (GitHub Copilot)
-
-            // Get all commits in this PR using the GitHub API
-            const { data: commits } = await github.rest.pulls.listCommits({
-              owner: context.repo.owner,
-              repo: context.repo.repo,
-              pull_number: context.payload.pull_request.number,
-            });
-
-            // Check each commit message for closing keywords
-            const violatingCommits = [];
-            // Matches: closes #123, fixes #123, closes: #123, etc.
-            const closingPattern = /(closes|fixes|resolves|fixed|closed|resolved):?\s+#\d+/i;
-
-            for (const commit of commits) {
-              const message = commit.commit.message;
-              if (closingPattern.test(message)) {
-                const shortSha = commit.sha.substring(0, 7);
-                const firstLine = message.split('\n')[0];
-                violatingCommits.push({ sha: shortSha, message: firstLine });
-              }
-            }
-
-            // Report results
-            if (violatingCommits.length > 0) {
-              let errorMessage = `Found ${violatingCommits.length} commit(s) with issue closing keywords:\n\n`;
-              for (const commit of violatingCommits) {
-                errorMessage += `- ${commit.sha}: ${commit.message}\n`;
-              }
-              errorMessage += `\nCommit messages should not contain closing keywords (closes, fixes, resolves, etc.). Use the PR description instead.`;
-              core.setFailed(errorMessage);
-            } else {
-              core.info('✓ No commits with issue closing keywords found');
-            }
+            const script = require('./tools/check-closes-discussion.cjs')
+            await script({ github, context, core })
 
   # Runs a full `semantic-release` dry-run for the state that would exist right
   # after this PR merges, and fails if it would publish a new *major* version.
diff --git a/tools/check-closes-discussion.cjs b/tools/check-closes-discussion.cjs
new file mode 100644
index 0000000000..9ffeba771f
--- /dev/null
+++ b/tools/check-closes-discussion.cjs
@@ -0,0 +1,97 @@
+// Co-authored-by: Claude Sonnet 4.5 (GitHub Copilot)
+
+/**
+ * @param {{ github: any, context: any, core: any }} params
+ */
+module.exports = async ({ github, context, core }) => {
+  // Get all commits in this PR using the GitHub API
+  const { data: commits } = await github.rest.pulls.listCommits({
+    owner: context.repo.owner,
+    repo: context.repo.repo,
+    pull_number: context.payload.pull_request.number,
+  });
+
+  // GitHub honours closing keywords in both commit messages and the
+  // PR description. `#123` may refer to a Discussion rather than an
+  // Issue - since Issues and Discussions are numbered independently
+  // - and closing keywords must not auto-close a Discussion (see
+  // #45439, which unintentionally closed discussion #40885).
+  // Matches: closes #123, fixes #123, closes: #123, etc.
+  const closingPattern =
+    /(closes|fixes|resolves|fixed|closed|resolved):?\s+#(\d+)/gi;
+
+  // Collect every closing-keyword reference, keeping one example
+  // line per source for the error report.
+  const references = new Map(); // number -> { source, line }
+  /**
+   * @param {string} text
+   * @param {string} source
+   */
+  function collect(text, source) {
+    for (const match of text.matchAll(closingPattern)) {
+      const number = match[2];
+      if (!references.has(number)) {
+        const line = text.slice(0, match.index).split('\n').length;
+        const lineText = text.split('\n')[line - 1].trim();
+        references.set(number, { source, line: lineText });
+      }
+    }
+  }
+
+  for (const commit of commits) {
+    const shortSha = commit.sha.substring(0, 7);
+    collect(commit.commit.message, `commit ${shortSha}`);
+  }
+  collect(context.payload.pull_request.body ?? '', 'PR description');
+
+  // Only fail for references that resolve to a Discussion - an
+  // Issue reference is the intended, supported use of these
+  // keywords (see the PR template).
+  const violations = [];
+  for (const [number, { source, line }] of references) {
+    let isIssue = true;
+    try {
+      await github.rest.issues.get({
+        owner: context.repo.owner,
+        repo: context.repo.repo,
+        issue_number: parseInt(number, 10),
+      });
+    } catch (err) {
+      if (err.status !== 404) {
+        throw err;
+      }
+      isIssue = false;
+    }
+    if (isIssue) {
+      continue;
+    }
+
+    const { repository } = await github.graphql(
+      `query($owner: String!, $repo: String!, $number: Int!) {
+        repository(owner: $owner, name: $repo) {
+          discussion(number: $number) { id }
+        }
+      }`,
+      {
+        owner: context.repo.owner,
+        repo: context.repo.repo,
+        number: parseInt(number, 10),
+      },
+    );
+    if (repository.discussion) {
+      violations.push({ source, line });
+    }
+  }
+
+  // Report results
+  if (violations.length > 0) {
+    let errorMessage = `Found ${violations.length} closing keyword(s) referencing a Discussion:\n\n`;
+    for (const violation of violations) {
+      errorMessage += `- ${violation.source}: ${violation.line}\n`;
+    }
+    errorMessage += `\nClosing keywords (closes, fixes, resolves, etc.) must not reference a Discussion, as merging would auto-close it. Reference the discussion without a closing keyword instead, e.g. 'Related discussion: #123'.`;
+    core.setFailed(errorMessage);
+  } else {
+    core.info('✓ No closing keywords referencing a Discussion found');
+  }
+};