diff --git a/.github/workflows/check-links.yml b/.github/workflows/check-links.yml
index c5e4d7503..78629e1fc 100644
--- a/.github/workflows/check-links.yml
+++ b/.github/workflows/check-links.yml
@@ -43,12 +43,14 @@ jobs:
                   git worktree add "$RUNNER_TEMP/base" "$merge_base"
                   git diff -U0 "$merge_base" HEAD > "$RUNNER_TEMP/changes.diff"
 
+            # The script exits 1 both with findings and when it crashes. It writes
+            # its output in one go at the end, so a crash leaves it empty. A crash
+            # does not fail the check, since it says nothing about the PR; the
+            # comment step reports it instead of posting the empty report.
             - name: Record broken links already present on the base branch
-              # Exit 1 means findings, which is expected here
               run: |
                   node dev/check-links.mjs --check-anchors --check-self-links --format json \
-                      --root "$RUNNER_TEMP/base" > "$RUNNER_TEMP/base-links.json" \
-                      || [ $? -eq 1 ]
+                      --root "$RUNNER_TEMP/base" > "$RUNNER_TEMP/base-links.json" || true
 
             - name: Find broken links introduced by this PR
               id: check
@@ -56,14 +58,22 @@ jobs:
                   # File links in the report open the file on the PR branch
                   LINK_BASE: ${{ github.event.pull_request.head.repo.html_url }}/blob/${{ github.event.pull_request.head.ref }}
               run: |
+                  if ! [ -s "$RUNNER_TEMP/base-links.json" ]; then
+                      echo "::warning::check-links crashed on the base branch, so this PR was not checked"
+                      echo "result=crashed" >> "$GITHUB_OUTPUT"
+                      exit 0
+                  fi
                   if node dev/check-links.mjs --check-anchors --check-self-links --check-external --format markdown \
                       --baseline "$RUNNER_TEMP/base-links.json" \
                       --diff "$RUNNER_TEMP/changes.diff" \
                       --review "$RUNNER_TEMP/review.json" \
                       --link-base "$LINK_BASE" > "$RUNNER_TEMP/report.md"; then
-                      echo "broken=false" >> "$GITHUB_OUTPUT"
+                      echo "result=clean" >> "$GITHUB_OUTPUT"
+                  elif [ -s "$RUNNER_TEMP/report.md" ]; then
+                      echo "result=broken" >> "$GITHUB_OUTPUT"
                   else
-                      echo "broken=true" >> "$GITHUB_OUTPUT"
+                      echo "::warning::check-links crashed, so this PR was not checked"
+                      echo "result=crashed" >> "$GITHUB_OUTPUT"
                   fi
                   cat "$RUNNER_TEMP/report.md"
 
@@ -73,21 +83,25 @@ jobs:
               env:
                   GH_TOKEN: ${{ github.token }}
                   PR_NUMBER: ${{ github.event.pull_request.number }}
-                  BROKEN: ${{ steps.check.outputs.broken }}
+                  RESULT: ${{ steps.check.outputs.result }}
+                  RUN_URL: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}
               run: |
                   marker='<!-- check-links-report -->'
                   existing_comment=$(gh api "repos/$GITHUB_REPOSITORY/issues/$PR_NUMBER/comments" \
                       --paginate --jq ".[] | select(.body | startswith(\"$marker\")) | .id" | head -n 1)
 
-                  # Comment only when there is something to report, or an earlier report to resolve
-                  if [ "$BROKEN" = true ]; then
-                      { echo "$marker"; cat "$RUNNER_TEMP/report.md"; } > "$RUNNER_TEMP/comment.md"
-                  elif [ -n "$existing_comment" ]; then
-                      printf '%s\n### ✅ The broken links an earlier revision of this PR introduced are fixed\n' \
-                          "$marker" > "$RUNNER_TEMP/comment.md"
-                  else
-                      exit 0
-                  fi
+                  # Comment when there is something to report, or an earlier report to resolve
+                  case "$RESULT" in
+                      broken)
+                          { echo "$marker"; cat "$RUNNER_TEMP/report.md"; } > "$RUNNER_TEMP/comment.md" ;;
+                      crashed)
+                          printf '%s\n### ⚠️ The links check could not run on this revision\n\nThis is a problem with the check, not with this PR; see the [job log](%s).\n' \
+                              "$marker" "$RUN_URL" > "$RUNNER_TEMP/comment.md" ;;
+                      *)
+                          [ -n "$existing_comment" ] || exit 0
+                          printf '%s\n### ✅ This revision introduces no broken links\n' \
+                              "$marker" > "$RUNNER_TEMP/comment.md" ;;
+                  esac
 
                   if [ -n "$existing_comment" ]; then
                       gh api --method PATCH "repos/$GITHUB_REPOSITORY/issues/comments/$existing_comment" \
@@ -99,12 +113,14 @@ jobs:
             - name: Suggest fixes as review comments
               # One suggested change per finding with a fix, kept in sync with the
               # findings; see dev/sync-review-comments.sh
-              if: github.event.pull_request.head.repo.full_name == github.repository
+              if: >-
+                  github.event.pull_request.head.repo.full_name == github.repository
+                  && contains(fromJSON('["clean", "broken"]'), steps.check.outputs.result)
               env:
                   GH_TOKEN: ${{ github.token }}
                   PR_NUMBER: ${{ github.event.pull_request.number }}
               run: dev/sync-review-comments.sh '<!-- check-links-finding:' "$RUNNER_TEMP/review.json"
 
             - name: Fail when this PR introduces broken links
-              if: steps.check.outputs.broken == 'true'
+              if: steps.check.outputs.result == 'broken'
               run: exit 1
diff --git a/.github/workflows/check-redirects.yml b/.github/workflows/check-redirects.yml
index 706bd254e..ce4658f95 100644
--- a/.github/workflows/check-redirects.yml
+++ b/.github/workflows/check-redirects.yml
@@ -44,12 +44,15 @@ jobs:
                   git worktree add "$RUNNER_TEMP/base" "$merge_base"
                   git diff -U0 "$merge_base" HEAD -- src/data/redirects.ts > "$RUNNER_TEMP/changes.diff"
 
+            # The script exits 1 both with findings and when it crashes, e.g. because
+            # this PR's copy of it cannot read the base branch's redirects.ts. It
+            # writes its output in one go at the end, so a crash leaves it empty.
+            # A crash does not fail the check, since it says nothing about the PR;
+            # the comment step reports it instead of posting the empty report.
             - name: Record broken redirects already present on the base branch
-              # Exit 1 means findings, which is expected here
               run: |
                   node dev/check-redirects.mjs --format json \
-                      --root "$RUNNER_TEMP/base" > "$RUNNER_TEMP/base-redirects.json" \
-                      || [ $? -eq 1 ]
+                      --root "$RUNNER_TEMP/base" > "$RUNNER_TEMP/base-redirects.json" || true
 
             - name: Find redirects broken by this PR
               id: check
@@ -57,14 +60,22 @@ jobs:
                   # Line links in the report open redirects.ts on the PR branch
                   LINK_BASE: ${{ github.event.pull_request.head.repo.html_url }}/blob/${{ github.event.pull_request.head.ref }}
               run: |
+                  if ! [ -s "$RUNNER_TEMP/base-redirects.json" ]; then
+                      echo "::warning::check-redirects crashed on the base branch, so this PR was not checked"
+                      echo "result=crashed" >> "$GITHUB_OUTPUT"
+                      exit 0
+                  fi
                   if node dev/check-redirects.mjs --format markdown \
                       --baseline "$RUNNER_TEMP/base-redirects.json" \
                       --diff "$RUNNER_TEMP/changes.diff" \
                       --review "$RUNNER_TEMP/review.json" \
                       --link-base "$LINK_BASE" > "$RUNNER_TEMP/report.md"; then
-                      echo "broken=false" >> "$GITHUB_OUTPUT"
+                      echo "result=clean" >> "$GITHUB_OUTPUT"
+                  elif [ -s "$RUNNER_TEMP/report.md" ]; then
+                      echo "result=broken" >> "$GITHUB_OUTPUT"
                   else
-                      echo "broken=true" >> "$GITHUB_OUTPUT"
+                      echo "::warning::check-redirects crashed, so this PR was not checked"
+                      echo "result=crashed" >> "$GITHUB_OUTPUT"
                   fi
                   cat "$RUNNER_TEMP/report.md"
 
@@ -74,21 +85,25 @@ jobs:
               env:
                   GH_TOKEN: ${{ github.token }}
                   PR_NUMBER: ${{ github.event.pull_request.number }}
-                  BROKEN: ${{ steps.check.outputs.broken }}
+                  RESULT: ${{ steps.check.outputs.result }}
+                  RUN_URL: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}
               run: |
                   marker='<!-- check-redirects-report -->'
                   existing_comment=$(gh api "repos/$GITHUB_REPOSITORY/issues/$PR_NUMBER/comments" \
                       --paginate --jq ".[] | select(.body | startswith(\"$marker\")) | .id" | head -n 1)
 
-                  # Comment only when there is something to report, or an earlier report to resolve
-                  if [ "$BROKEN" = true ]; then
-                      { echo "$marker"; cat "$RUNNER_TEMP/report.md"; } > "$RUNNER_TEMP/comment.md"
-                  elif [ -n "$existing_comment" ]; then
-                      printf '%s\n### ✅ The redirects an earlier revision of this PR broke are fixed\n' \
-                          "$marker" > "$RUNNER_TEMP/comment.md"
-                  else
-                      exit 0
-                  fi
+                  # Comment when there is something to report, or an earlier report to resolve
+                  case "$RESULT" in
+                      broken)
+                          { echo "$marker"; cat "$RUNNER_TEMP/report.md"; } > "$RUNNER_TEMP/comment.md" ;;
+                      crashed)
+                          printf '%s\n### ⚠️ The redirects check could not run on this revision\n\nThis is a problem with the check, not with this PR; see the [job log](%s).\n' \
+                              "$marker" "$RUN_URL" > "$RUNNER_TEMP/comment.md" ;;
+                      *)
+                          [ -n "$existing_comment" ] || exit 0
+                          printf '%s\n### ✅ This revision breaks no redirects\n' \
+                              "$marker" > "$RUNNER_TEMP/comment.md" ;;
+                  esac
 
                   if [ -n "$existing_comment" ]; then
                       gh api --method PATCH "repos/$GITHUB_REPOSITORY/issues/comments/$existing_comment" \
@@ -100,12 +115,14 @@ jobs:
             - name: Suggest fixes as review comments
               # One suggested change per fixable entry this PR added, kept in sync
               # with the findings; see dev/sync-review-comments.sh
-              if: github.event.pull_request.head.repo.full_name == github.repository
+              if: >-
+                  github.event.pull_request.head.repo.full_name == github.repository
+                  && contains(fromJSON('["clean", "broken"]'), steps.check.outputs.result)
               env:
                   GH_TOKEN: ${{ github.token }}
                   PR_NUMBER: ${{ github.event.pull_request.number }}
               run: dev/sync-review-comments.sh '<!-- check-redirects-finding:' "$RUNNER_TEMP/review.json"
 
             - name: Fail when this PR breaks redirects
-              if: steps.check.outputs.broken == 'true'
+              if: steps.check.outputs.result == 'broken'
               run: exit 1
diff --git a/.github/workflows/spellcheck.yml b/.github/workflows/spellcheck.yml
index b881f9691..51f98bae8 100644
--- a/.github/workflows/spellcheck.yml
+++ b/.github/workflows/spellcheck.yml
@@ -37,6 +37,7 @@ jobs:
               run: npm install --global cspell@10
 
             - name: Find spelling errors introduced by this PR
+              id: check
               # Title and description come in through env, never inline in the
               # script, so a crafted pull request cannot inject shell commands
               env:
@@ -46,10 +47,18 @@ jobs:
               run: |
                   base=$(git merge-base "$BASE_SHA" HEAD)
                   printf '%s\n\n%s\n' "$PR_TITLE" "$PR_BODY" > "$RUNNER_TEMP/pull-request.md"
-                  # Exit 1 means findings; anything else is an operational error
+                  # The script exits 1 both with findings and when it crashes at import
+                  # time. It writes its output in one go at the end, so a crash leaves
+                  # it empty. A crash does not fail the check, since it says nothing
+                  # about the PR; the report step says so instead of posting the
+                  # empty report
                   node dev/check-spelling.mjs --base "$base" \
                       --pull-request "$RUNNER_TEMP/pull-request.md" --format json \
-                      > "$RUNNER_TEMP/spelling.json" || [ "$?" -eq 1 ]
+                      > "$RUNNER_TEMP/spelling.json" || true
+                  if ! [ -s "$RUNNER_TEMP/spelling.json" ]; then
+                      echo "::warning::check-spelling crashed, so this PR was not checked"
+                      echo "crashed=true" >> "$GITHUB_OUTPUT"
+                  fi
                   cat "$RUNNER_TEMP/spelling.json"
 
             - name: Report on the pull request
@@ -60,4 +69,11 @@ jobs:
                   PR_NUMBER: ${{ github.event.pull_request.number }}
                   HEAD_SHA: ${{ github.event.pull_request.head.sha }}
                   HEAD_REF: ${{ github.event.pull_request.head.ref }}
-              run: node dev/post-spelling-review.mjs --findings "$RUNNER_TEMP/spelling.json"
+                  RUN_URL: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}
+                  CRASHED: ${{ steps.check.outputs.crashed }}
+              run: |
+                  if [ "$CRASHED" = true ]; then
+                      node dev/post-spelling-review.mjs --crashed
+                  else
+                      node dev/post-spelling-review.mjs --findings "$RUNNER_TEMP/spelling.json"
+                  fi
diff --git a/AGENTS.md b/AGENTS.md
index 5718c4250..c2fd71c5a 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -21,7 +21,10 @@
 - **Check redirects**: `node dev/check-redirects.mjs` reports broken entries in
   `src/data/redirects.ts` (CI comments on PRs that break redirects; see the
   script header for what it checks). Not part of `pnpm run check`: main has
-  hundreds of pre-existing findings, and CI only reports the ones a PR adds
+  hundreds of pre-existing findings, and CI only reports the ones a PR adds.
+  When a check script crashes, CI comments that the check could not run,
+  linking the job log, instead of failing the PR: an empty report says nothing
+  about the PR
 - **Prove changed links resolve on a deploy**:
   `node dev/verify-links-live.mjs --site <vercel-preview-url>` prints a
   Markdown table for the PR description
diff --git a/cspell-allow-list.txt b/cspell-allow-list.txt
index c8d8eac88..13256d9ac 100644
--- a/cspell-allow-list.txt
+++ b/cspell-allow-list.txt
@@ -190,6 +190,7 @@ entrycommand
 envsubst
 errgroup
 errorf
+esac
 esbenp
 Eswatini
 etcdctl
diff --git a/dev/check-redirects.mjs b/dev/check-redirects.mjs
index f13831db8..f84d0e191 100644
--- a/dev/check-redirects.mjs
+++ b/dev/check-redirects.mjs
@@ -120,9 +120,12 @@ function loadRedirects() {
 			/TECHNICAL_CHANGELOG_RSS_URL\s*=\s*['"]([^'"]+)['"]/
 		)?.[1] ?? '';
 
+	// CI runs this revision of the script against the base branch too, so
+	// accept both export styles the file has used
 	const script = source
 		.replace(/^import .*$/gm, '')
 		.replace(/^export const /gm, 'const ')
+		.replace(/^export \{.*$/gm, '')
 		.replace(/module\.exports\s*=\s*\{[\s\S]*?\};?/g, '');
 
 	const sandbox = {TECHNICAL_CHANGELOG_RSS_URL: rssUrl};
diff --git a/dev/post-spelling-review.mjs b/dev/post-spelling-review.mjs
index 1ec455175..15d30044c 100644
--- a/dev/post-spelling-review.mjs
+++ b/dev/post-spelling-review.mjs
@@ -10,8 +10,11 @@
  * visible.
  *
  * Usage: node dev/post-spelling-review.mjs --findings <json-file> [--dry-run]
+ *        node dev/post-spelling-review.mjs --crashed [--dry-run]
  *
- * Reads the JSON written by `dev/check-spelling.mjs --format json`.
+ * Reads the JSON written by `dev/check-spelling.mjs --format json`. With
+ * `--crashed`, the summary says the check could not run and links the job log
+ * (RUN_URL) instead; the inline comments are left as they are.
  * Requires GH_TOKEN, GITHUB_REPOSITORY, PR_NUMBER, HEAD_SHA and HEAD_REF.
  */
 
@@ -19,6 +22,7 @@ import {readFileSync} from 'fs';
 
 const args = process.argv.slice(2);
 const FINDINGS_FILE = args[args.indexOf('--findings') + 1];
+const CRASHED = args.includes('--crashed');
 const DRY_RUN = args.includes('--dry-run');
 const MAX_INLINE_COMMENTS = 25;
 
@@ -27,6 +31,7 @@ const REPOSITORY = process.env.GITHUB_REPOSITORY;
 const PR_NUMBER = process.env.PR_NUMBER;
 const HEAD_SHA = process.env.HEAD_SHA;
 const HEAD_REF = process.env.HEAD_REF;
+const RUN_URL = process.env.RUN_URL;
 
 // Link to the PR branch, not the commit, so GitHub's edit button works from it
 const ALLOW_LIST_LINK = `[\`cspell-allow-list.txt\`](https://github.com/${REPOSITORY}/blob/${HEAD_REF}/cspell-allow-list.txt)`;
@@ -168,7 +173,22 @@ function summaryBody(findings) {
 	return lines.join('\n') + '\n';
 }
 
-async function upsertSummaryComment(findings) {
+function crashedBody() {
+	return [
+		SUMMARY_MARKER,
+		'### ⚠️ The spell check could not run on this revision',
+		'',
+		`This is a problem with the check, not with this PR; see the [job log](${RUN_URL}).`,
+		''
+	].join('\n');
+}
+
+const RESOLVED_BODY = `${SUMMARY_MARKER}\n### ✅ This revision introduces no spelling errors\n`;
+
+// Post the summary, or replace the earlier one. A resolved summary is kept,
+// collapsed, so the discussion still shows what was flagged and fixed; it is
+// reopened when there is something to say again.
+async function upsertSummaryComment(body, resolved) {
 	const comments = await githubList(
 		`/repos/${REPOSITORY}/issues/${PR_NUMBER}/comments`
 	);
@@ -177,27 +197,21 @@ async function upsertSummaryComment(findings) {
 	);
 
 	if (!existing) {
-		if (findings.length > 0) {
+		// Nothing to resolve
+		if (!resolved) {
 			await githubWrite(
 				'POST',
 				`/repos/${REPOSITORY}/issues/${PR_NUMBER}/comments`,
-				{body: summaryBody(findings)}
+				{body}
 			);
 		}
 		return;
 	}
 
-	// Keep the earlier report, collapsed as resolved, so the discussion still
-	// shows what was flagged and fixed. Reopen it when new findings appear.
-	const resolved = findings.length === 0;
 	await githubWrite(
 		'PATCH',
 		`/repos/${REPOSITORY}/issues/comments/${existing.id}`,
-		{
-			body: resolved
-				? `${SUMMARY_MARKER}\n### ✅ The spelling errors reported on an earlier revision are fixed\n`
-				: summaryBody(findings)
-		}
+		{body}
 	);
 	await setCommentMinimized(existing.node_id, resolved);
 }
@@ -323,13 +337,25 @@ async function main() {
 			throw new Error(`Missing required environment variable ${name}`);
 		}
 	}
+	if (CRASHED) {
+		if (!RUN_URL) {
+			throw new Error('Missing required environment variable RUN_URL');
+		}
+		console.log('Reporting that the check crashed');
+		await upsertSummaryComment(crashedBody(), false);
+		return;
+	}
 	if (!FINDINGS_FILE) {
 		throw new Error('Missing required --findings <json-file>');
 	}
 
 	const findings = JSON.parse(readFileSync(FINDINGS_FILE, 'utf8'));
 	console.log(`${findings.length} finding(s) to report`);
-	await upsertSummaryComment(findings);
+	const resolved = findings.length === 0;
+	await upsertSummaryComment(
+		resolved ? RESOLVED_BODY : summaryBody(findings),
+		resolved
+	);
 	await syncInlineComments(findings);
 }