Local preview — fix ERR_CONNECTION_REFUSED on localhost:3123

GitHub Pages HTML under docs/ and the investor Next.js app both use port 3123 for local preview. Nothing listens until you start a server.

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Option A — static docs (GitHub Pages export)

From repo root:

cd docs
npx --yes serve . -l 3123

Or use the helper script:

.\scripts\preview-pages-3123.ps1

Open:

• http://localhost:3123/technical/SYSTEM_MANIFEST.html
• http://localhost:3123/technical/ARBITRAGE_AND_BAAS.html

If you previously opened http://localhost:3123 with no path and saw ERR_CONNECTION_REFUSED, the fix is simply running one of the commands above first.

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Option B — investor Next.js dev server

cd sites\investor
npm install
npm run dev

package.json sets next dev -p 3123. Use the app's basePath when testing production-like URLs (see sites/investor/DEPLOY.md).

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Option C — full technical HTML sync

After editing docs/technical/*.md:

npm run docs:update

Then serve with Option A.

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Troubleshooting

Symptom	Fix
ERR_CONNECTION_REFUSED	Start serve or npm run dev — port 3123 is not started by PM2
Wrong paths / 404	Use serve from docs/ folder, or investor basePath per DEPLOY.md
Firewall block	Allow Node on private network once