askrene: add optional layers to reservations.

We have the issue of aliases: xpay uses scids like 0x0x0 for
routehints and blinded paths, and then can apply reservations to them.  But
generally, reservations are *global*, so we need to differentiate.

Changelog-Added: Plugins: `askrene-reserve` and `askrene-unreserve` can take an optional `layer` inside `path` elements.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Author: rustyrussell

.msggen.json

@@ -752,6 +752,7 @@
         "Askrene-reservePath": {
             "AskRene-Reserve.path[].amount_msat": 3,
             "AskRene-Reserve.path[].direction": 2,
+            "AskRene-Reserve.path[].layer": 5,
             "AskRene-Reserve.path[].short_channel_id": 1,
             "AskRene-Reserve.path[].short_channel_id_dir": 4
         },
@@ -761,6 +762,7 @@
         "Askrene-unreservePath": {
             "AskRene-Unreserve.path[].amount_msat": 3,
             "AskRene-Unreserve.path[].direction": 2,
+            "AskRene-Unreserve.path[].layer": 5,
             "AskRene-Unreserve.path[].short_channel_id": 1,
             "AskRene-Unreserve.path[].short_channel_id_dir": 4
         },
@@ -4412,6 +4414,10 @@
             "added": "v24.08",
             "deprecated": null
         },
+        "AskRene-Reserve.path[].layer": {
+            "added": "v25.12",
+            "deprecated": null
+        },
         "AskRene-Reserve.path[].short_channel_id": {
             "added": "v24.08",
             "deprecated": null
@@ -4436,6 +4442,10 @@
             "added": "v24.08",
             "deprecated": null
         },
+        "AskRene-Unreserve.path[].layer": {
+            "added": "v25.12",
+            "deprecated": null
+        },
         "AskRene-Unreserve.path[].short_channel_id": {
             "added": "v24.08",
             "deprecated": null

cln-grpc/proto/node.proto

@@ -873,7 +873,7 @@
           "layer": {
             "type": "string",
             "description": [
-              "The name of the layer to apply this change to."
+              "The name of the layer to apply this change to.  Also causes us to consider any reservations which are local to that layer (which is useful for fake channels where `layer` is set in an `askrene-reserve` `path` object)."
             ]
           },
           "short_channel_id_dir": {
@@ -1553,6 +1553,13 @@
                   "description": [
                     "The amount to send into this hop."
                   ]
+                },
+                "layer": {
+                  "added": "v25.12",
+                  "type": "string",
+                  "description": [
+                    "The layer to restrict this reservation to.  This is only useful for fake channels which are not uniquely identified by `short_channel_id_dir`, which would otherwise confuse multiple unrelated callers."
+                  ]
                 }
               }
             }
@@ -1654,6 +1661,13 @@
                   "description": [
                     "The amount to send into this hop."
                   ]
+                },
+                "layer": {
+                  "added": "v25.12",
+                  "type": "string",
+                  "description": [
+                    "The layer to restrict this reservation to (useful for fake channels)."
+                  ]
                 }
               }
             }

cln-grpc/src/convert.rs

@@ -5,7 +5,7 @@
 
 from pyln.grpc import node_pb2 as node__pb2
 
-GRPC_GENERATED_VERSION = '1.69.0'
+GRPC_GENERATED_VERSION = '1.75.1'
 GRPC_VERSION = grpc.__version__
 _version_not_supported = False
 

cln-rpc/src/model.rs

@@ -19,7 +19,7 @@
       "layer": {
         "type": "string",
         "description": [
-          "The name of the layer to apply this change to."
+          "The name of the layer to apply this change to.  Also causes us to consider any reservations which are local to that layer (which is useful for fake channels where `layer` is set in an `askrene-reserve` `path` object)."
         ]
       },
       "short_channel_id_dir": {

contrib/msggen/msggen/schema.json

@@ -36,6 +36,13 @@
               "description": [
                 "The amount to send into this hop."
               ]
+            },
+            "layer": {
+              "added": "v25.12",
+              "type": "string",
+              "description": [
+                "The layer to restrict this reservation to.  This is only useful for fake channels which are not uniquely identified by `short_channel_id_dir`, which would otherwise confuse multiple unrelated callers."
+              ]
             }
           }
         }

contrib/pyln-grpc-proto/pyln/grpc/node_pb2.py

@@ -36,6 +36,13 @@
               "description": [
                 "The amount to send into this hop."
               ]
+            },
+            "layer": {
+              "added": "v25.12",
+              "type": "string",
+              "description": [
+                "The layer to restrict this reservation to (useful for fake channels)."
+              ]
             }
           }
         }