feat: add Nostr zap support (NIP-57) for splitpayments

config.json

@@ -54,5 +54,14 @@
   ],
   "description_md": "https://raw.githubusercontent.com/lnbits/splitpayments/main/description.md",
   "terms_and_conditions_md": "https://raw.githubusercontent.com/lnbits/splitpayments/main/toc.md",
-  "license": "MIT"
+  "license": "MIT",
+  "nostr_signing": [
+    {
+      "kind": 9734,
+      "kind_label": "Zap Request",
+      "description": "Signs NIP-57 zap requests when splitting payments to LNURL targets that support zaps.",
+      "required": false,
+      "recommended_rate_limit": {"count": 100, "seconds": 86400}
+    }
+  ]
 }

crud.py

@@ -1,6 +1,7 @@
 from lnbits.db import Database
+from lnbits.helpers import decrypt_internal_message, encrypt_internal_message
 
-from .models import Target
+from .models import SplitPaymentSettings, Target
 
 db = Database("ext_splitpayments")
 
@@ -21,3 +22,46 @@ async def set_targets(source_wallet: str, targets: list[Target]):
         )
         for target in targets:
             await conn.insert("splitpayments.targets", target)
+
+
+async def get_splitpayment_settings(
+    wallet_id: str,
+) -> SplitPaymentSettings:
+    settings = await db.fetchone(
+        "SELECT * FROM splitpayments.settings WHERE wallet = :wallet",
+        {"wallet": wallet_id},
+        SplitPaymentSettings,
+    )
+    if settings:
+        decrypted_key = decrypt_internal_message(settings.nostr_private_key)
+        if decrypted_key:
+            # strip PKCS7 padding bytes left by AES decryption
+            settings.nostr_private_key = "".join(
+                c for c in decrypted_key if c >= " "
+            )
+        return settings
+    return SplitPaymentSettings(wallet=wallet_id, nostr_private_key="")
+
+
+async def update_splitpayment_settings(
+    wallet_id: str,
+    settings: SplitPaymentSettings,
+) -> SplitPaymentSettings:
+    encrypted_key = encrypt_internal_message(settings.nostr_private_key)
+    encrypted_settings = SplitPaymentSettings(
+        wallet=wallet_id,
+        nostr_private_key=encrypted_key or "",
+    )
+    await db.execute(
+        "DELETE FROM splitpayments.settings WHERE wallet = :wallet",
+        {"wallet": wallet_id},
+    )
+    await db.insert("splitpayments.settings", encrypted_settings)
+    return settings
+
+
+async def delete_splitpayment_settings(wallet_id: str) -> None:
+    await db.execute(
+        "DELETE FROM splitpayments.settings WHERE wallet = :wallet",
+        {"wallet": wallet_id},
+    )

helpers.py

@@ -0,0 +1,8 @@
+from pynostr.key import PrivateKey
+
+
+def parse_nostr_private_key(key: str) -> PrivateKey:
+    if key.startswith("nsec"):
+        return PrivateKey.from_nsec(key)
+    else:
+        return PrivateKey(bytes.fromhex(key))

migrations.py

@@ -102,7 +102,7 @@ async def m003_add_id_and_tag(db: Connection):
                 "wallet": row["wallet"],
                 "source": row["source"],
                 "percent": row["percent"],
-                "tag": row["tag"],
+                "tag": "",
                 "alias": row["alias"],
             },
         )
@@ -134,3 +134,64 @@ async def m004_remove_tag(db: Connection):
     )
     await db.execute(f"INSERT INTO {new_db} ({keys}) SELECT {keys} FROM {old_db}")
     await db.execute(f"DROP TABLE {old_db}")
+
+
+async def m005_add_settings(db: Connection):
+    """
+    Add extension settings table for Nostr zap support.
+    """
+    await db.execute(
+        """
+        CREATE TABLE splitpayments.settings (
+            nostr_private_key TEXT NOT NULL
+        );
+        """
+    )
+
+
+async def m006_add_wallet_to_settings(db: Connection):
+    """
+    Add wallet column to settings table for per-wallet Nostr key support.
+    """
+    # Check if wallet column already exists (idempotent)
+    result = await db.execute(
+        """
+        SELECT column_name FROM information_schema.columns
+        WHERE table_schema = 'splitpayments'
+          AND table_name = 'settings'
+          AND column_name = 'wallet'
+        """
+    )
+    rows = result.mappings().all()
+    if rows:
+        return  # already migrated
+
+    await db.execute(
+        "ALTER TABLE splitpayments.settings ADD COLUMN wallet TEXT NOT NULL DEFAULT ''"
+    )
+    await db.execute(
+        """
+        ALTER TABLE splitpayments.settings
+        DROP CONSTRAINT IF EXISTS settings_pkey
+        """
+    )
+    # Recreate the table with wallet as primary key
+    await db.execute(
+        "ALTER TABLE splitpayments.settings RENAME TO settings_m005"
+    )
+    await db.execute(
+        """
+        CREATE TABLE splitpayments.settings (
+            wallet TEXT PRIMARY KEY,
+            nostr_private_key TEXT NOT NULL
+        );
+        """
+    )
+    await db.execute(
+        """
+        INSERT INTO splitpayments.settings (wallet, nostr_private_key)
+        SELECT wallet, nostr_private_key FROM splitpayments.settings_m005
+        WHERE wallet != ''
+        """
+    )
+    await db.execute("DROP TABLE splitpayments.settings_m005")

models.py

@@ -2,6 +2,9 @@
 
 from fastapi import Query
 from pydantic import BaseModel
+from pynostr.key import PrivateKey
+
+from .helpers import parse_nostr_private_key
 
 
 class Target(BaseModel):
@@ -20,3 +23,16 @@ class TargetPut(BaseModel):
 
 class TargetPutList(BaseModel):
     targets: list[TargetPut]
+
+
+class SplitPaymentSettings(BaseModel):
+    wallet: str = ""
+    nostr_private_key: str = ""
+
+    @property
+    def private_key(self) -> PrivateKey:
+        return parse_nostr_private_key(self.nostr_private_key)
+
+    @property
+    def public_key(self) -> str:
+        return self.private_key.public_key.hex()

static/js/index.js

@@ -6,11 +6,7 @@ function hashTargets(targets) {
 }
 
 function isTargetComplete(target) {
-  return (
-    target.wallet &&
-    target.wallet.trim() !== '' &&
-    (target.percent > 0 || target.tag != '')
-  )
+  return target.wallet && target.wallet.trim() !== '' && target.percent > 0
 }
 
 window.app = Vue.createApp({
@@ -25,12 +21,22 @@ window.app = Vue.createApp({
     return {
       selectedWallet: null,
       currentHash: '', // a string that must match if the edit data is unchanged
-      targets: []
+      targets: [],
+      settingsOptions: [
+        {
+          type: 'str',
+          description: 'Nostr private key used to sign zap requests (hex or nsec)',
+          name: 'nostr_private_key'
+        }
+      ]
     }
   },
   computed: {
     isDirty() {
       return hashTargets(this.targets) !== this.currentHash
+    },
+    settingsEndpoint() {
+      return '/splitpayments/api/v1/settings'
     }
   },
   methods: {
@@ -53,6 +59,7 @@ window.app = Vue.createApp({
         )
         .then(response => {
           this.targets = response.data
+          this.currentHash = hashTargets(this.targets)
         })
         .catch(err => {
           LNbits.utils.notifyApiError(err)
@@ -63,7 +70,7 @@ window.app = Vue.createApp({
       this.getTargets()
     },
     addTarget() {
-      this.targets.push({source: this.selectedWallet})
+      this.targets.push({wallet: '', percent: 0, alias: ''})
     },
     saveTargets() {
       LNbits.api
@@ -76,6 +83,7 @@ window.app = Vue.createApp({
           }
         )
         .then(response => {
+          this.currentHash = hashTargets(this.targets)
           Quasar.Notify.create({
             message: 'Split payments targets set.',
             timeout: 700