agntn · oritwoen · Sep 5, 2026 · Sep 5, 2026
@@ -2,7 +2,7 @@
 
 ## OVERVIEW
 
-TypeScript library providing a unified interface for key generation, address derivation, wallet creation, and message signing across 8 blockchains (Bitcoin, Ethereum, Base, Solana, Aptos, Cardano, SUI, TRON). Built entirely on the @noble/@scure audited crypto ecosystem.
+TypeScript library providing a unified interface for key generation, address derivation, wallet creation, and message signing across 9 blockchains (Bitcoin, Litecoin, Ethereum, Base, Solana, Aptos, Cardano, SUI, TRON). Built entirely on the @noble/@scure audited crypto ecosystem.
 
 ## STRUCTURE
 
@@ -30,19 +30,20 @@ keys/
 
 ## WHERE TO LOOK
 
-| Task               | Location                                                                          | Notes                                                      |
-| ------------------ | --------------------------------------------------------------------------------- | ---------------------------------------------------------- |
-| Add new blockchain | `src/blockchains/` + `src/_blockchains.ts`                                        | Extend the appropriate base class, register in lazy loader |
-| Add address format | `src/utils/address.ts`                                                            | Shared across chains (legacy, segwit, hex, base58)         |
-| Add EVM chain      | `src/utils/evm.ts` → `AbstractEVMBlockchain`                                      | Minimal subclass with `name` and `bip44`                   |
-| Fix signing        | `src/utils/signing.ts` (generic) or `evm.ts`/`ed25519-chains.ts` (chain-specific) | EVM uses preamble hash, ed25519 signs raw                  |
-| Change public API  | `src/index.ts`                                                                    | Re-exports only, never add logic here                      |
-| Change agent tools | `src/tool-operations.ts`, `src/mcp.ts`, `packages/pi/extensions/keys.ts`          | Executors are shared; schemas stay aligned                 |
-| Add BIP/derivation | `src/utils/bip32/`, `bip39/`, `bip44/`, `slip10/`                                 | Subdirs with index.ts                                      |
-| Mnemonic to wallet | `src/blockchain.ts` → `deriveHDWallet` + `src/utils/hd.ts`                        | Bitcoin and Sui override it, Cardano throws (CIP-1852)     |
-| Write tests        | `test/` mirroring `src/` path                                                     | Use fixtures from `test/fixtures.ts`                       |
-| Integration test   | `test-integration/`                                                               | Separate pnpm package, manual execution                    |
-| Run demos          | `playground/*.ts`                                                                 | Execute via `pnpm playground <file>`                       |
+| Task               | Location                                                                          | Notes                                                                                |
+| ------------------ | --------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------ |
+| Add new blockchain | `src/blockchains/` + `src/_blockchains.ts`                                        | Extend the appropriate base class, register in lazy loader                           |
+| Add address format | `src/utils/address.ts`                                                            | Shared across chains (legacy, segwit, hex, base58)                                   |
+| Add Bitcoin family | `src/utils/bitcoin.ts` → `AbstractBitcoinBlockchain`                              | Reuse transparent address and HD behavior; keep chain signing rules explicit         |
+| Add EVM chain      | `src/utils/evm.ts` → `AbstractEVMBlockchain`                                      | Minimal subclass with `name` and `bip44`                                             |
+| Fix signing        | `src/utils/signing.ts` (generic) or `evm.ts`/`ed25519-chains.ts` (chain-specific) | EVM uses preamble hash, ed25519 signs raw                                            |
+| Change public API  | `src/index.ts`                                                                    | Re-exports only, never add logic here                                                |
+| Change agent tools | `src/tool-operations.ts`, `src/mcp.ts`, `packages/pi/extensions/keys.ts`          | Executors are shared; schemas stay aligned                                           |
+| Add BIP/derivation | `src/utils/bip32/`, `bip39/`, `bip44/`, `slip10/`                                 | Subdirs with index.ts                                                                |
+| Mnemonic to wallet | `src/blockchain.ts` → `deriveHDWallet` + `src/utils/hd.ts`                        | Bitcoin/Litecoin infer the address type; Sui overrides it, Cardano throws (CIP-1852) |
+| Write tests        | `test/` mirroring `src/` path                                                     | Use fixtures from `test/fixtures.ts`                                                 |
+| Integration test   | `test-integration/`                                                               | Separate pnpm package, manual execution                                              |
+| Run demos          | `playground/*.ts`                                                                 | Execute via `pnpm playground <file>`                                                 |
 
 ## CONVENTIONS
 

@@ -5,7 +5,7 @@
 [![license](https://img.shields.io/github/license/agntn/keys?style=flat&colorA=130f40&colorB=474787)](https://github.com/agntn/keys/blob/main/LICENSE.md)
 [![Ask DeepWiki](https://deepwiki.com/badge.svg)](https://deepwiki.com/agntn/keys)
 
-Typed key generation, address derivation, and message signing across eight blockchains and two curves.
+Typed key generation, address derivation, and message signing across nine blockchains and two curves.
 
 > [!WARNING]
 > **@agntn/keys is experimental.** The package name, public API, provider model, and tool surfaces may change before the first stable release. Pin exact versions if you build on it now.
@@ -68,6 +68,22 @@ const testnet = useBlockchain(await blockchains.bitcoin({ network: "testnet" })(
 testnet.getAddress(publicKey, "segwit"); // tb1q...
 ```
 
+### Litecoin
+
+```ts
+import { blockchains } from "@agntn/keys";
+
+const mnemonic =
+  "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about";
+const ltc = await blockchains.litecoin()();
+const wallet = ltc.deriveHDWallet(mnemonic, "m/84'/2'/0'/0/0");
+const testnet = await blockchains.litecoin({ network: "testnet" })();
+```
+
+Litecoin uses the same five address types as Bitcoin, with `L`/`M`/`ltc1` on mainnet and `m` or `n`/`Q`/`tltc1` on testnet. Old P2SH prefixes (`3` and `2`) are accepted, not generated. Those old addresses overlap with Bitcoin, so validation alone cannot identify the chain. MWEB and regtest are outside this implementation.
+
+Message signing uses the Litecoin Core message digest and returns a compact signature of 64 bytes as hex, not Core's recoverable base64 format. Verify against the public key with `verifyMessage`.
+
 ### Sign and verify messages
 
 ```ts
@@ -124,7 +140,7 @@ const sol = useBlockchain(await blockchains.solana()());
 sol.deriveHDWallet(mnemonic, "m/44'/501'/0'/0'", { passphrase: "TREZOR" }).address;
 ```
 
-secp256k1 chains walk BIP32 and ed25519 chains walk SLIP-10, which accepts hardened segments only. Bitcoin reads the address type off the purpose level (44, 49, 84, 86) unless one is passed. Cardano throws, because CIP-1852 starts from the entropy rather than the BIP39 seed.
+secp256k1 chains walk BIP32 and ed25519 chains walk SLIP-10, which accepts hardened segments only. Bitcoin and Litecoin read the address type off the purpose level (44, 49, 84, 86) unless one is passed. Cardano throws, because CIP-1852 starts from the entropy rather than the BIP39 seed.
 
 ### Recover one missing BIP39 word
 
@@ -173,6 +189,7 @@ The server handles private keys, mnemonics, entropy, messages, and signatures as
 | Chain        | Curve              | Address Formats                      | Testnet |
 | ------------ | ------------------ | ------------------------------------ | ------- |
 | **Bitcoin**  | secp256k1          | legacy, p2sh, segwit, p2wsh, taproot | ✅      |
+| **Litecoin** | secp256k1          | legacy, p2sh, segwit, p2wsh, taproot | ✅      |
 | **Ethereum** | secp256k1          | EIP-55 checksum                      | -       |
 | **Base**     | secp256k1          | EVM-compatible                       | -       |
 | **Solana**   | ed25519            | base58                               | -       |

@@ -15,6 +15,7 @@ export default defineBuildConfig({
         "./src/blockchains/aptos.ts",
         "./src/blockchains/base.ts",
         "./src/blockchains/bitcoin.ts",
+        "./src/blockchains/litecoin.ts",
         "./src/blockchains/cardano.ts",
         "./src/blockchains/ethereum.ts",
         "./src/blockchains/solana.ts",

@@ -51,9 +51,9 @@ export default function keysExtension(pi: ExtensionAPI) {
     promptSnippet:
       "Use to create a new wallet with keys and address for Bitcoin, Ethereum, Solana, etc.",
     promptGuidelines: [
-      "Provide a chain name (bitcoin, ethereum, base, solana, aptos, tron, sui, cardano)",
+      "Provide a chain name (bitcoin, litecoin, ethereum, base, solana, aptos, tron, sui, cardano)",
       "Optionally specify network (mainnet/testnet) and address type",
-      "Bitcoin address types: legacy, p2sh, segwit, p2wsh, taproot",
+      "Bitcoin and Litecoin address types: legacy, p2sh, segwit, p2wsh, taproot",
       "Cardano address types: payment, stake, enterprise",
       "Returns hex private key, hex public key, and address",
     ],
@@ -84,7 +84,7 @@ export default function keysExtension(pi: ExtensionAPI) {
     promptGuidelines: [
       "Provide a chain name and private key as hex",
       "Optionally specify network and address type",
-      "Bitcoin address types: legacy, p2sh, segwit, p2wsh, taproot",
+      "Bitcoin and Litecoin address types: legacy, p2sh, segwit, p2wsh, taproot",
       "For Sui, use ed25519 or secp256k1 as the address type",
     ],
     parameters: Type.Object({
@@ -115,7 +115,7 @@ export default function keysExtension(pi: ExtensionAPI) {
     promptGuidelines: [
       "Provide a chain, an English BIP39 mnemonic, and a full derivation path",
       "Common paths: Bitcoin m/44'/0'/0'/0/0 (legacy), m/49'/0'/0'/0/0 (p2sh), m/84'/0'/0'/0/0 (segwit), m/86'/0'/0'/0/0 (taproot); Ethereum m/44'/60'/0'/0/0; Solana m/44'/501'/0'/0'; Aptos m/44'/637'/0'/0'/0'; Sui m/44'/784'/0'/0'/0'",
-      "Bitcoin picks the address type from the path purpose unless addressType is set",
+      "Bitcoin and Litecoin pick the address type from the path purpose unless addressType is set",
       "Optionally pass a BIP39 passphrase, a network, or an address type",
       "Cardano is not supported because CIP-1852 derives from entropy, not from the BIP39 seed",
       "Use only public or disposable mnemonics because tool arguments are saved in the transcript",
@@ -374,7 +374,7 @@ export default function keysExtension(pi: ExtensionAPI) {
     promptGuidelines: [
       "Provide chain, message text, and private key (hex)",
       "Returns the signature as hex string",
-      "Bitcoin uses its own message preamble format",
+      "Bitcoin and Litecoin each use their own message preamble",
       "Ethereum/Base use EIP-191 prefix",
     ],
     parameters: Type.Object({

@@ -22,6 +22,7 @@ function lazy<T extends AbstractBlockchain>(loader: () => Promise<BlockchainModu
  */
 export const blockchains = {
   bitcoin: lazy(() => import("./blockchains/bitcoin.ts")),
+  litecoin: lazy(() => import("./blockchains/litecoin.ts")),
   solana: lazy(() => import("./blockchains/solana.ts")),
   aptos: lazy(() => import("./blockchains/aptos.ts")),
   tron: lazy(() => import("./blockchains/tron.ts")),

@@ -9,7 +9,8 @@ Lazy-loaded class modules. Each file exports a named concrete class and the same
 | Family               | Chains                 | Signing                                           | Key Derivation                      |
 | -------------------- | ---------------------- | ------------------------------------------------- | ----------------------------------- |
 | **EVM**              | ethereum, base         | `evmSignMessage` (preamble + keccak256)           | secp256k1 via `utils/secp256k1`     |
-| **secp256k1 custom** | bitcoin, tron          | `evmSignMessage` (same signing, custom addresses) | secp256k1 via `utils/secp256k1`     |
+| **Bitcoin family**   | bitcoin, litecoin      | chain-specific message preamble                   | secp256k1 via `utils/secp256k1`     |
+| **secp256k1 custom** | tron                   | `evmSignMessage` (same signing, custom addresses) | secp256k1 via `utils/secp256k1`     |
 | **ed25519**          | solana, aptos, cardano | `ed25519SignMessage` (raw, no prehash)            | ed25519 via `utils/ed25519`         |
 | **dual-curve**       | sui                    | both (selected via `options.scheme`)              | ed25519 default, secp256k1 optional |
 
@@ -24,11 +25,12 @@ Lazy-loaded class modules. Each file exports a named concrete class and the same
 
 ## PATTERNS
 
+- **Bitcoin base class** - `AbstractBitcoinBlockchain` in `utils/bitcoin.ts` shares address generation and HD purpose inference. Litecoin signs its Core digest with noble prehash disabled and accepts both P2SH prefix generations.
 - **EVM base class** - `Ethereum` and `Base` extend `AbstractEVMBlockchain`, which owns their shared key, address, validation, and signing behavior
-- **Network params** - Bitcoin and Cardano keep separate address parameters for each network in `NETWORK_PARAMS`; TRON uses `0x41` and `T` on mainnet, Shasta, and Nile
+- **Network params** - Bitcoin, Litecoin, and Cardano keep separate address parameters for each network in `NETWORK_PARAMS`; TRON uses `0x41` and `T` on mainnet, Shasta, and Nile
 - **BIP44 coin type** - every chain sets `bip44` from `BIP44` enum or SLIP-0044 number
 - **SUI dual-curve** - `getKeyPublic` and `signMessage` check `options.scheme` to pick ed25519 or secp256k1
-- **HD wallets** - `deriveHDWallet` on the base class walks BIP32 or SLIP-10 by curve; Bitcoin infers the address type from the path purpose, Sui takes the curve from the scheme, Cardano throws because CIP-1852 derives differently
+- **HD wallets** - `deriveHDWallet` on the base class walks BIP32 or SLIP-10 by curve; Bitcoin and Litecoin infer the address type from the path purpose, Sui takes the curve from the scheme, Cardano throws because CIP-1852 derives differently
 
 ## COMPLEXITY