feat(internal-explorer): confirm before switching explorer hosts

[niran]

Summary

• Internal Explorer chain toggle stays on this origin for same-host chains (Mainnet ↔ Sepolia on prod; any chain when BASE_UI_*_HOST is unset). Other-host toggles open a confirm modal, then window.location.assign to the destination with ?chain= and other query params preserved.
• Default chain when ?chain= is missing follows the request host: zeronet on BASE_UI_ZERONET_HOST, mainnet on the mainnet/sepolia host, mainnet when hosts are unset. Explicit ?chain= is never redirected on load.
• Hosts are runtime env (BASE_UI_ZERONET_HOST, BASE_UI_MAINNET_HOST, BASE_UI_SEPOLIA_HOST), matching protocols/ui#21. Same image on both deploys; no NEXT_PUBLIC_*.

Test plan

• Local npm run dev:internal with hosts unset: /internal-explorer defaults to Mainnet; toggling chains does not prompt
• With Helm hosts set, Host: base-ui.aws-dev.cbhq.net /internal-explorer defaults to Zeronet; Host: base-ui.aws.cbhq.net defaults to Mainnet
• ?chain=mainnet on aws-dev stays on aws-dev (no auto-redirect); audit for that chain is disabled there
• Toggle Mainnet on aws-dev: modal names the prod host; Cancel leaves chain/host unchanged; Continue navigates to prod with ?chain=mainnet
• Check Don't show this again, Continue, then toggle again: navigates immediately
• npx vitest run app/api/internal-explorer/hosts.test.ts

type=routine
risk=low
impact=sev5

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
omni-ui	Ready	Preview	Aug 25, 2026 9:11pm

[cb-heimdall]

🟡 Heimdall Review Status

Requirement	Status	More Info
Reviews	🟡 0/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1