Implementation Notes

This document records the web wallet implementation direction chosen for adding the Photon regtest backend without breaking the current working wallet.

Design

Keep the current public backend as the default behavior.
Add a second backend profile: Photon Dev Regtest.
Route Bitcoin HTTP API calls through a profile-aware resolver instead of hardcoded public URLs.
Only use Photon dev HTTP endpoints for regtest when that profile is selected.
Keep mainnet/testnet behavior on the existing public APIs unless the user explicitly changes it later.

Implemented Scope

Added backend profile support to the web wallet settings flow.
Added profile-aware Bitcoin API base resolution.
Updated fee, address-history, UTXO, activity, and broadcast helpers to use that resolver.
Updated RGB occupied UTXO fetching to reuse the configured Bitcoin backend instead of a hardcoded explorer URL.

Profiles

legacy-public: preserves the current public mempool/blockstream behavior.
photon-dev-regtest: uses Photon dev endpoints only for regtest.

Photon Regtest Defaults

Electrum: ssl://dev-index.photonbolt.xyz:50002
RGB proxy: https://dev-proxy.photonbolt.xyz/json-rpc
Bitcoin adapter base: https://dev-api.photonbolt.xyz/api

Remaining Requirement

The web wallet routing is now prepared for the Photon regtest adapter, but the adapter service itself still needs to exist at dev-api.photonbolt.xyz for regtest requests to succeed under that profile.