Vitest Storybook Browser Mode CI Disk Space Failures

Random `Failed to fetch dynamically imported module`, iframe disconnects, or browser connection closes can be real test bugs, but they can also be a disk-pressure symptom when Chromium, Vite, or the CI runner fills temporary storage mid-run.

Useful symptoms

• Different stories fail on different runs.
• The same suite passes locally but fails on GitHub Actions or Azure DevOps.
• CI logs include `No space left on device` or disk warnings near the failure.
• Firefox passes slowly while Chromium fails or hangs.
• Sharding reduces failures because each runner handles less browser state.

Capture evidence before changing config

Add this around the browser-mode test step so each failure has disk, temp, and deleted-open-file evidence.

echo "== before =="
df -h
du -sh /tmp "$RUNNER_TEMP" "$GITHUB_WORKSPACE" 2>/dev/null || true

pnpm test:sb
status=$?

echo "== after =="
df -h
du -sh /tmp "$RUNNER_TEMP" "$GITHUB_WORKSPACE" 2>/dev/null || true

echo "== deleted open Chromium temp files =="
for fd in /proc/[0-9]*/fd/*; do
  target=$(readlink "$fd" 2>/dev/null) || continue
  case "$target" in
    *"(deleted)"*)
      size=$(stat -Lc '%s' "$fd" 2>/dev/null || echo 0)
      pid=${fd#/proc/}; pid=${pid%%/*}
      cmd=$(tr '\0' ' ' < "/proc/$pid/cmdline" 2>/dev/null)
      printf '%12s  pid=%-7s  %s  -> %s\n' "$size" "$pid" "$cmd" "$target"
      ;;
  esac
done | grep -Ei 'chrome|chromium|playwright|vite|vitest' | sort -nr | head -80 || true

exit "$status"

Separate three failure classes

1. Vite dependency optimization reload: look for `optimized dependencies changed. reloading` and add the named packages to `optimizeDeps.include`.
2. Chromium temp pressure: look for many deleted-open `/tmp/.org.chromium.*` files and test Playwright launch flags, sharding, or lower browser concurrency.
3. Runner storage exhaustion: check if workspace, artifacts, pnpm cache, Playwright browsers, or browser results consume the limited runner disk.

Safer fixes to try first

• Cache Vite optimized dependencies or explicitly include packages that optimize mid-run.
• Shard large Storybook suites before deleting cache folders blindly.
• Keep a disk snapshot in CI logs so future failures are measurable.
• Review Playwright/Chromium temp behavior before switching all tests to Firefox only.