looprpc: add scriptable autoloop RPC fields

Add new fields to LiquidityParameters for scriptable autoloop:

- scriptable_autoloop (bool): Enable scriptable autoloop mode
- scriptable_script (string): The Starlark script content
- scriptable_tick_interval_sec (uint64): Custom tick interval

These fields allow clients to configure scriptable autoloop via the
SetLiquidityParams RPC. The script is validated on the server side
before being accepted.

Author: sputn1ck

looprpc/client.pb.go

@@ -1287,6 +1287,32 @@ message LiquidityParameters {
     considered for easy autoloop swaps.
     */
     repeated bytes easy_autoloop_excluded_peers = 27;
+
+    /*
+    Set to true to enable scriptable autoloop using Starlark scripts. If set,
+    all channel/peer rules and easy autoloop will be overridden and the client
+    will evaluate the configured Starlark script on each tick to determine
+    swaps. This mode is mutually exclusive with easy_autoloop and threshold
+    rules. Starlark is a Python-like language that supports variables,
+    functions, loops, and sorting - making it much more readable and powerful
+    than simple expressions.
+    */
+    bool scriptable_autoloop = 28;
+
+    /*
+    The Starlark script to evaluate on each autoloop tick. Required if
+    scriptable_autoloop is true. The script must set a 'decisions' variable
+    to a list of swap decisions using the loop_out() and loop_in() helper
+    functions. See documentation for available context variables (channels,
+    peers, total_local, restrictions, etc.) and helper functions.
+    */
+    string scriptable_script = 29;
+
+    /*
+    Optional custom tick interval in seconds for scriptable autoloop mode.
+    If 0 or not set, uses the default 20-minute interval.
+    */
+    uint64 scriptable_tick_interval_sec = 30;
 }
 
 message EasyAssetAutoloopParams {

looprpc/client.proto

@@ -1796,6 +1796,19 @@
             "format": "byte"
           },
           "description": "A list of peers (their public keys) that should be excluded from the easy\nautoloop run. If set, channels connected to these peers won't be\nconsidered for easy autoloop swaps."
+        },
+        "scriptable_autoloop": {
+          "type": "boolean",
+          "description": "Set to true to enable scriptable autoloop using Starlark scripts. If set,\nall channel/peer rules and easy autoloop will be overridden and the client\nwill evaluate the configured Starlark script on each tick to determine\nswaps. This mode is mutually exclusive with easy_autoloop and threshold\nrules. Starlark is a Python-like language that supports variables,\nfunctions, loops, and sorting - making it much more readable and powerful\nthan simple expressions."
+        },
+        "scriptable_script": {
+          "type": "string",
+          "description": "The Starlark script to evaluate on each autoloop tick. Required if\nscriptable_autoloop is true. The script must set a 'decisions' variable\nto a list of swap decisions using the loop_out() and loop_in() helper\nfunctions. See documentation for available context variables (channels,\npeers, total_local, restrictions, etc.) and helper functions."
+        },
+        "scriptable_tick_interval_sec": {
+          "type": "string",
+          "format": "uint64",
+          "description": "Optional custom tick interval in seconds for scriptable autoloop mode.\nIf 0 or not set, uses the default 20-minute interval."
         }
       }
     },