feat: Add Testnet4 and Signet network support

[Sukuna0007Abhi]

Resolves #356

• Added TESTNET4 network enum value
• Implemented custom network configurations for Signet and Testnet4
• Updated networkData() to return proper network objects for all networks
• Updated networkLabel() to return 'Testnet3' for clarity and added labels for Testnet4, Signet, and Regtest
• Added Testnet4 and Signet support in transactions/utils.ts with custom network definitions
• Updated BlockchainClient to validate and support Testnet4 and Signet networks
• Updated Blockstream provider validation to indicate it doesn't support Testnet4 or Signet
• Added comprehensive tests for all new network types
• Updated BitcoinIcon component to include TESTNET4 type

This change addresses the confusion around Testnet versions and adds support for Testnet4 which is now used by default in Trezor Connect.

Issue Number:

Fixes #356

Snapshots/Videos:

If relevant, did you update the documentation?

probably no need

Checklist

• I have tested my changes thoroughly.
• I have added or updated tests to cover my changes (if applicable).
• I have verified that test coverage meets or exceeds 95% (if applicable).
• I have run the test suite locally, and all tests pass.
• I have written tests for all new changes/features
• I have followed the project's coding style and conventions.
• I have created a changeset to document my changes (npm run changeset)

Pls review @bucko13 @Legend101Zz

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Project	Deployment	Actions	Updated (UTC)
caravan-coordinator	Ready	Preview, Comment	Feb 4, 2026 8:08pm

[Legend101Zz]

Thanks for the PR @Sukuna0007Abhi .... on my first review , I guess the PR is not complete yet . The changes in the packages are necessary but not sufficient. You'll also need coordinator (frontend) changes to fully support Testnet4 and Signet.

listing down the changes you'll need :

• apps/coordinator/src/components/NetworkPicker.jsx
  ( currently only has radio buttons for Mainnet, Testnet (3), and Regtest. You'll need to add Testnet4 and Signet options )

• packages/caravan-bitcoin/src/block_explorer.ts
  (needs updating to handle Testnet4 and Signet , urls )

• apps/coordinator/src/components/ClientPicker/index.jsx
  ( needs to handle port selection for private bitcoind clients on new networks , and also the ClientPicker already checks isRegtest to disable public explorers. You might want to add a check to warn users that Blockstream doesn't support Testnet4 or Signet)

• apps/coordinator/src/selectors/wallet.ts , also I guess has some network specific logic

also one main thing , the wallet config we have currently stores network config as ( when a user downloads there wallet ) :

  "name": "My Multisig Wallet",
  "uuid": "abc123...",
  "addressType": "P2WSH",
  "network": "testnet",  // ← Network is stored here
  "client": {
    "type": "public",
    "provider": "mempool"
  },
  "quorum": {
    "requiredSigners": 2,
    "totalSigners": 3
  },
  "extendedPublicKeys": [...],
  "startingAddressIndex": 0,
  "ledgerPolicyHmacs": []
}

we'd want it to look like

{
  "name": "My Testnet4 Wallet",
  "uuid": "550e8400-e29b-41d4-a716-446655440000",
  "addressType": "P2WSH",
  "network": "testnet4",
  "client": {
    "type": "public",
    "provider": "mempool"
  },
  "quorum": {
    "requiredSigners": 2,
    "totalSigners": 3
  },
  "extendedPublicKeys": [
    {
      "name": "Key 1",
      "bip32Path": "m/48'/1'/0'/2'",
      "xpub": "tpub...",
      "xfp": "aabbccdd",
      "method": "trezor"
    }
  ],
  "startingAddressIndex": 0,
  "ledgerPolicyHmacs": []
}

so you might want to look at apps/coordinator/src/selectors/wallet.ts

this will also let you connect caravan to testnet4 and check if everything works :)

Signet I am not sure if you'd be able to test it ....

PS: @bucko13 does this make sense to you the change in network in wallet config ?

[Legend101Zz]

can we just export both signet and testnet4, so in transactions package we would not need to redefine them ?