Hermes Update Hangs on Web UI Build | Generated by AI

Home 2026.06

Question: Why does hermes update (Hermes Agent) get stuck at “→ Building web UI…” after installing the repo root + ui-tui and web workspace packages?

Answer:

It’s almost certainly not stuck — it’s silent. The “Building web UI…” step runs the web workspace’s build script, which is:

tsc -b && vite build

The hermes update spinner swallows the subprocess’s stdout until the step finishes, and tsc -b (TypeScript project-references build) emits zero output while type-checking. On a cold cache (fresh node_modules, no .tsbuildinfo), tsc -b over ~2,200+ modules can take several minutes — especially on your 16 GB M2 Air where tsc + npm’s leftover memory pressure can push you into swap. The vite part itself takes ~3s once tsc clears, as shown in a recent identical report on the repo: the same update sequence on macOS shows “added 769 packages in 7s ✓ repo root + ui-tui, web workspaces (desktop skipped) → Building web UI…” sitting on a spinner, then eventually completing with “vite v7.3.2 … ✓ 2257 modules transformed … ✓ built in 2.92s ✓ Web UI built”.

Debug it in 30 seconds instead of guessing:

# 1. Is anything actually working? Look for tsc/vite eating CPU
ps aux | grep -E 'tsc|vite|esbuild' | grep -v grep
# tsc at ~100% CPU = building, not hung

# 2. If you want real output, kill the update and build manually
cd ~/.hermes/hermes-agent/web
npx tsc -b --verbose   # shows per-project progress
npm run build          # full vite output

# 3. Then resume
hermes update

Two things worth fixing while you’re in there:

  1. Node version. The same logs show npm EBADENGINE warnings: @icons-pack/react-simple-icons@13.13.0 requires node >=24 while the system has v22.x. It’s a warning not a failure, but you’re one transitive dep away from a silent runtime break. nvm install 24 && nvm use 24 (or mise use node@24).

  2. Swap check on the Air. If ps shows tsc alive but crawling, check vm_stat | grep -E 'Pageouts|swap'. With 16 GB and a fat npm install just finished, tsc can thrash. Quitting browsers/Electron apps before hermes update genuinely helps here.

If tsc -b errors out (rather than hanging), the spinner UI can also mask the non-zero exit — the manual npm run build in step 2 will surface the actual TypeScript error immediately. If the web frontend never gets built (e.g. npm unavailable or reduced PATH), the documented manual fallback is cd ~/.hermes/hermes-agent/web && npm install && npm run build, then relaunch — the dashboard serves whatever exists in web_dist. Production builds output to hermes_cli/web_dist/, which the FastAPI server serves as a static SPA; hermes update only rebuilds the frontend automatically if npm is available.

One more data point: in the linked issue the real hang was one step later — “→ Building desktop packaged app…” stalls inside electron-builder during packaging. Your run says (desktop skipped), so you’ve dodged that one; yours is just tsc being mute.

References:

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