xpay: add xkeysend support.

diff --git a/contrib/msggen/msggen/schema.json b/contrib/msggen/msggen/schema.json
index 03f31c53..e2db77cd 100644
--- a/contrib/msggen/msggen/schema.json
+++ b/contrib/msggen/msggen/schema.json
@@ -38678,6 +38678,142 @@
         }
       ]
     },
+    "xkeysend.json": {
+      "$schema": "../rpc-schema-draft.json",
+      "type": "object",
+      "rpc": "xkeysend",
+      "title": "Send funds to a node without an invoice",
+      "added": "v26.06",
+      "description": [
+        "The **xkeysend** RPC command attempts to find a route to the given destination, and send the specified amount to it. Unlike the `xpay` RPC command the `xkeysend` command does not require an invoice, instead it uses the `destination` node ID, and `amount` to find a route to the specified node.",
+        "",
+        "In order for the destination to be able to claim the payment, the `payment_key` is randomly generated by the sender and included in the encrypted payload for the destination. As a consequence there is not proof-of-payment, like there is with an invoice where the `payment_key` is generated on the destination, and the only way sender could have it is by sending a payment. Please ensure that this matches your use-case when using `xkeysend`.",
+        "",
+        "This replaces the older `keysend` command."
+      ],
+      "request": {
+        "required": [
+          "destination",
+          "amount_msat"
+        ],
+        "additionalProperties": false,
+        "properties": {
+          "destination": {
+            "type": "pubkey",
+            "description": [
+              "The 33 byte, hex-encoded, node ID of the node that the payment should go to."
+            ]
+          },
+          "amount_msat": {
+            "type": "msat",
+            "description": [
+              "A whole number, or a whole number with suffix `msat` or `sat`, or a three decimal point number with suffix `sat`, or an 1 to 11 decimal point number suffixed by `btc`."
+            ]
+          },
+          "label": {
+            "type": "string",
+            "description": [
+              "Attach a label to the payment for which is returned in `listpays` and `listsendpays`.  This is for your own use: it is not visible to the recipient."
+            ]
+          },
+          "maxfee": {
+            "type": "msat",
+            "description": [
+              "*maxfee* creates an absolute limit on what fee we will pay."
+            ]
+          },
+          "layers": {
+            "type": "array",
+            "description": [
+              "These are askrene layers to apply: these can alter the topology or provide additional information on the lightning network.  See askrene-create-layer."
+            ],
+            "items": {
+              "type": "string",
+              "description": [
+                "name of an existing layer"
+              ]
+            }
+          },
+          "retry_for": {
+            "type": "u32",
+            "description": [
+              "Until *retry_for* seconds passes, the command will keep finding routes and retrying the payment. However, a payment may be delayed for up to `maxdelay` blocks by another node; clients should be prepared for this worst case."
+            ],
+            "default": "60 seconds"
+          },
+          "maxdelay": {
+            "type": "u32",
+            "description": [
+              "Number of blocks the payment may be delayed."
+            ]
+          },
+          "extratlvs": {
+            "type": "object",
+            "additionalProperties": true,
+            "required": [],
+            "description": [
+              "Dictionary of additional fields to insert into the final tlv. The format is 'fieldnumber': 'hexstring'."
+            ]
+          }
+        }
+      },
+      "response": {
+        "required": [
+          "payment_preimage",
+          "failed_parts",
+          "successful_parts",
+          "amount_msat",
+          "amount_sent_msat"
+        ],
+        "properties": {
+          "payment_preimage": {
+            "type": "secret",
+            "description": [
+              "The proof of payment: SHA256 of this **payment_hash**."
+            ]
+          },
+          "failed_parts": {
+            "type": "u64",
+            "description": [
+              "How many separate payment parts failed."
+            ]
+          },
+          "successful_parts": {
+            "type": "u64",
+            "description": [
+              "How many separate payment parts succeeded (or are anticipated to succeed).  This will be at least one."
+            ]
+          },
+          "amount_msat": {
+            "type": "msat",
+            "description": [
+              "Amount the recipient received."
+            ]
+          },
+          "amount_sent_msat": {
+            "type": "msat",
+            "description": [
+              "Total amount we sent (including fees)."
+            ]
+          }
+        },
+        "post_return_value_notes": [
+          "Note that the return is the same as it is for `xpay`."
+        ]
+      },
+      "author": [
+        "Rusty Russell [rusty@rustcorp.com.au](mailto:rusty@rustcorp.com.au) is mainly responsible."
+      ],
+      "see_also": [
+        "lightning-listpays(7)",
+        "lightning-askrene-create-layer(7)",
+        "lightning-askrene-create-channel(7)",
+        "lightning-askrene-update-channel(7)"
+      ],
+      "resources": [
+        "Main web site: [https://github.com/ElementsProject/lightning](https://github.com/ElementsProject/lightning)"
+      ]
+    },
     "xpay.json": {
       "$schema": "../rpc-schema-draft.json",
       "type": "object",
diff --git a/doc/Makefile b/doc/Makefile
index 81e3fc47..39e6929d 100644
--- a/doc/Makefile
+++ b/doc/Makefile
@@ -159,6 +159,7 @@ MARKDOWNPAGES := doc/addgossip.7 \
 	doc/wait.7 \
 	doc/waitsendpay.7 \
 	doc/withdraw.7 \
+	doc/xkeysend.7 \
 	doc/xpay.7
 
 NOTIFICATION_SCHEMAS := $(wildcard doc/schemas/notification/*.json)
diff --git a/doc/index.rst b/doc/index.rst
index 96c3443e..26d38b63 100644
--- a/doc/index.rst
+++ b/doc/index.rst
@@ -215,5 +215,6 @@ Core Lightning Documentation
    waitinvoice <waitinvoice.7.md>
    waitsendpay <waitsendpay.7.md>
    withdraw <withdraw.7.md>
+   xkeysend <xkeysend.7.md>
    xpay <xpay.7.md>
 .. block_end manpages
diff --git a/doc/schemas/xkeysend.json b/doc/schemas/xkeysend.json
new file mode 100644
index 00000000..e45983ba
--- /dev/null
+++ b/doc/schemas/xkeysend.json
@@ -0,0 +1,136 @@
+{
+  "$schema": "../rpc-schema-draft.json",
+  "type": "object",
+  "rpc": "xkeysend",
+  "title": "Send funds to a node without an invoice",
+  "added": "v26.06",
+  "description": [
+    "The **xkeysend** RPC command attempts to find a route to the given destination, and send the specified amount to it. Unlike the `xpay` RPC command the `xkeysend` command does not require an invoice, instead it uses the `destination` node ID, and `amount` to find a route to the specified node.",
+    "",
+    "In order for the destination to be able to claim the payment, the `payment_key` is randomly generated by the sender and included in the encrypted payload for the destination. As a consequence there is not proof-of-payment, like there is with an invoice where the `payment_key` is generated on the destination, and the only way sender could have it is by sending a payment. Please ensure that this matches your use-case when using `xkeysend`.",
+    "",
+    "This replaces the older `keysend` command."
+  ],
+  "request": {
+    "required": [
+      "destination",
+      "amount_msat"
+    ],
+    "additionalProperties": false,
+    "properties": {
+      "destination": {
+        "type": "pubkey",
+        "description": [
+          "The 33 byte, hex-encoded, node ID of the node that the payment should go to."
+        ]
+      },
+      "amount_msat": {
+        "type": "msat",
+        "description": [
+          "A whole number, or a whole number with suffix `msat` or `sat`, or a three decimal point number with suffix `sat`, or an 1 to 11 decimal point number suffixed by `btc`."
+        ]
+      },
+      "label": {
+        "type": "string",
+        "description": [
+          "Attach a label to the payment for which is returned in `listpays` and `listsendpays`.  This is for your own use: it is not visible to the recipient."
+        ]
+      },
+      "maxfee": {
+        "type": "msat",
+        "description": [
+          "*maxfee* creates an absolute limit on what fee we will pay."
+        ]
+      },
+      "layers": {
+        "type": "array",
+        "description": [
+          "These are askrene layers to apply: these can alter the topology or provide additional information on the lightning network.  See askrene-create-layer."
+        ],
+        "items": {
+          "type": "string",
+          "description": [
+            "name of an existing layer"
+          ]
+        }
+      },
+      "retry_for": {
+        "type": "u32",
+        "description": [
+          "Until *retry_for* seconds passes, the command will keep finding routes and retrying the payment. However, a payment may be delayed for up to `maxdelay` blocks by another node; clients should be prepared for this worst case."
+        ],
+        "default": "60 seconds"
+      },
+      "maxdelay": {
+        "type": "u32",
+        "description": [
+          "Number of blocks the payment may be delayed."
+        ]
+      },
+      "extratlvs": {
+        "type": "object",
+        "additionalProperties": true,
+        "required": [],
+        "description": [
+          "Dictionary of additional fields to insert into the final tlv. The format is 'fieldnumber': 'hexstring'."
+        ]
+      }
+    }
+  },
+  "response": {
+    "required": [
+      "payment_preimage",
+      "failed_parts",
+      "successful_parts",
+      "amount_msat",
+      "amount_sent_msat"
+    ],
+    "properties": {
+      "payment_preimage": {
+        "type": "secret",
+        "description": [
+          "The proof of payment: SHA256 of this **payment_hash**."
+        ]
+      },
+      "failed_parts": {
+        "type": "u64",
+        "description": [
+          "How many separate payment parts failed."
+        ]
+      },
+      "successful_parts": {
+        "type": "u64",
+        "description": [
+          "How many separate payment parts succeeded (or are anticipated to succeed).  This will be at least one."
+        ]
+      },
+      "amount_msat": {
+        "type": "msat",
+        "description": [
+          "Amount the recipient received."
+        ]
+      },
+      "amount_sent_msat": {
+        "type": "msat",
+        "description": [
+          "Total amount we sent (including fees)."
+        ]
+      }
+    },
+    "post_return_value_notes": [
+      "Note that the return is the same as it is for `xpay`."
+    ]
+  },
+  "author": [
+    "Rusty Russell [rusty@rustcorp.com.au](mailto:rusty@rustcorp.com.au) is mainly responsible."
+  ],
+  "see_also": [
+    "lightning-listpays(7)",
+    "lightning-askrene-create-layer(7)",
+    "lightning-askrene-create-channel(7)",
+    "lightning-askrene-update-channel(7)"
+  ],
+  "resources": [
+    "Main web site: [https://github.com/ElementsProject/lightning](https://github.com/ElementsProject/lightning)"
+  ]
+}
diff --git a/plugins/xpay/xpay.c b/plugins/xpay/xpay.c
index aa7b4efd..e6bda299 100644
--- a/plugins/xpay/xpay.c
+++ b/plugins/xpay/xpay.c
@@ -19,6 +19,7 @@
 #include <common/onion_encode.h>
 #include <common/onionreply.h>
 #include <common/pseudorand.h>
+#include <common/randbytes.h>
 #include <common/route.h>
 #include <common/wireaddr.h>
 #include <errno.h>
@@ -26,6 +27,8 @@
 #include <plugins/libplugin.h>
 #include <stdarg.h>
 
+#define PREIMAGE_TLV_TYPE 5482373484
+
 /* For the whole plugin */
 struct xpay {
 	struct pubkey local_id;
@@ -69,7 +72,7 @@ struct payment {
 	struct command *cmd;
 	/* Unique id */
 	u64 unique_id;
-	/* For logging, and for sendpays */
+	/* For logging, and for sendpays: NULL for xkeysend! */
 	const char *invstring;
 	/* Explicit layers they told us to include */
 	const char **layers;
@@ -978,6 +981,16 @@ static void update_knowledge_from_error(struct command *aux_cmd,
 	 */
 	if (from_final) {
 		switch (failcode) {
+		/* This is possible if we're keysending */
+		case WIRE_INVALID_ONION_PAYLOAD:
+			if (!attempt->payment->invstring) {
+				payment_give_up(aux_cmd, attempt->payment,
+						PAY_DESTINATION_PERM_FAIL,
+						"Destination reported %s (likely doesn't support keysend)",
+						errmsg);
+				return;
+			}
+			/* Fall thru */
 		/* These two are deprecated */
 		case WIRE_FINAL_INCORRECT_CLTV_EXPIRY:
 		case WIRE_FINAL_INCORRECT_HTLC_AMOUNT:
@@ -986,7 +999,6 @@ static void update_knowledge_from_error(struct command *aux_cmd,
 		case WIRE_INVALID_ONION_VERSION:
 		case WIRE_INVALID_ONION_HMAC:
 		case WIRE_INVALID_ONION_KEY:
-		case WIRE_INVALID_ONION_PAYLOAD:
 
 		/* These should not be sent by final node */
 		case WIRE_TEMPORARY_CHANNEL_FAILURE:
@@ -1412,7 +1424,11 @@ static struct command_result *do_inject(struct command *aux_cmd,
 	json_add_u32(req->js, "cltv_expiry", initial_cltv_delta(attempt) + effective_bheight);
 	json_add_u64(req->js, "partid", attempt->partid);
 	json_add_u64(req->js, "groupid", attempt->payment->group_id);
-	json_add_string(req->js, "invstring", attempt->payment->invstring);
+	/* Use invstring for payments, destination directly for keysend */
+	if (attempt->payment->invstring)
+		json_add_string(req->js, "invstring", attempt->payment->invstring);
+	else
+		json_add_pubkey(req->js, "destination", &attempt->payment->destination);
 	json_add_amount_msat(req->js, "destination_msat", attempt->delivers);
 	if (attempt->payment->localinvreqid)
 		json_add_sha256(req->js, "localinvreqid", attempt->payment->localinvreqid);
@@ -2324,7 +2340,7 @@ static struct payment *new_payment(const tal_t *ctx,
 	payment->deadline = timemono_add(time_mono(), time_from_sec(retryfor));
 	payment->start_blockheight = xpay->blockheight;
 	payment->cmd = cmd;
-	payment->invstring = tal_strdup(payment, invstring);
+	payment->invstring = tal_strdup_or_null(payment, invstring);
 	payment->localinvreqid = tal_dup_or_null(payment, struct sha256, localinvreqid);
 	if (label)
 		payment->label = json_escape_dup(payment, label);
@@ -2687,6 +2703,118 @@ static struct command_result *xpay_layer_created(struct command *aux_cmd,
 	return aux_command_done(aux_cmd);
 }
 
+static struct command_result *
+preapprovekeysend_succeed(struct command *cmd,
+			  const char *method,
+			  const char *buf,
+			  const jsmntok_t *result,
+			  struct payment *payment)
+{
+	/* Now we can conclude `check` command */
+	if (command_check_only(cmd)) {
+		return command_check_done(cmd);
+	}
+
+	/* Actually we don't need a private layer, but unification is easy. */
+	return populate_private_layer(cmd, payment);
+}
+
+static struct command_result *json_xkeysend(struct command *cmd,
+					    const char *buf,
+					    const jsmntok_t *params)
+{
+	struct xpay *xpay = xpay_of(cmd->plugin);
+	struct amount_msat *msat, *maxfee;
+	struct pubkey *dst;
+	u32 *maxdelay;
+	unsigned int *retryfor;
+	struct payment *payment;
+	struct json_escape *label;
+	const char *err;
+	struct preimage preimage;
+	struct sha256 payment_hash;
+	const char **layers;
+	struct tlv_field *extra_fields;
+	u8 *tlvs;
+	struct out_req *req;
+
+	if (!param_check(cmd, buf, params,
+			 p_req("destination", param_pubkey, &dst),
+			 p_req("amount_msat", param_msat, &msat),
+			 p_opt("label", param_label, &label),
+			 p_opt("maxfee", param_msat, &maxfee),
+			 p_opt("layers", param_string_array, &layers),
+			 p_opt_def("retry_for", param_number, &retryfor, 60),
+			 p_opt_def("maxdelay", param_number, &maxdelay, 2016),
+			 p_opt("extratlvs", param_extra_tlvs, &extra_fields),
+			 NULL))
+		return command_param_failed();
+
+	randbytes(&preimage, sizeof(preimage));
+	sha256(&payment_hash, &preimage, sizeof(preimage));
+
+	/* We explicitly prohibit self-keysends */
+	if (pubkey_eq(&xpay->local_id, dst)) {
+		return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+				    "We are the destination. Keysend cannot be used to send funds to yourself");
+	}
+
+	payment = new_payment(cmd, cmd,
+			      *retryfor,
+			      *maxdelay,
+			      layers,
+			      NULL, /* NULL invstring is the marker of a keysend vs pay */
+			      dst,
+			      &payment_hash,
+			      *msat,
+			      NULL,
+			      maxfee,
+			      NULL, NULL,
+			      // 22 is the Rust-Lightning default and the
+			      // highest minimum CLTV we know of.
+			      22,
+			      label,
+			      NULL,
+			      false,
+			      &err);
+	if (!payment)
+		return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+				    "%s", err);
+
+	if (!extra_fields)
+		extra_fields = tal_arr(cmd, struct tlv_field, 0);
+	tlvstream_set_raw(&extra_fields, PREIMAGE_TLV_TYPE,
+			  &preimage, sizeof(struct preimage));
+
+	/* Keysend only supports a single part, usually (we support multi!) */
+	payment->maxparts = 1;
+
+	/* Single payments should always use shadow routes */
+	payment->use_shadow = true;
+
+	/* Convert tlvs into their array representation for appending (assumes
+	 * they're greater than any TLV we set!) */
+	tlvs = tal_arr(payment, u8, 0);
+	towire_tlvstream_raw(&tlvs, extra_fields);
+	payment->extra_tlvs = tlvs;
+
+	/* We do pre-approval immediately (note: even if command_check_only!) */
+	if (command_check_only(cmd)) {
+		req = jsonrpc_request_start(cmd, "check",
+					    preapprovekeysend_succeed,
+					    forward_error, payment);
+		json_add_string(req->js, "command_to_check", "preapprovekeysend");
+	} else {
+		req = jsonrpc_request_start(cmd, "preapprovekeysend",
+					    preapprovekeysend_succeed,
+					    forward_error, payment);
+	}
+	json_add_pubkey(req->js, "destination", &payment->destination);
+	json_add_sha256(req->js, "payment_hash", &payment->payment_hash);
+	json_add_amount_msat(req->js, "amount_msat", payment->amount);
+	return send_outreq(req);
+}
+
 static const char *init(struct command *init_cmd,
 			const char *buf UNUSED, const jsmntok_t *config UNUSED)
 {
@@ -2739,6 +2867,10 @@ static const struct plugin_command commands[] = {
 		"xpay-as-pay",
 		json_xpay_as_pay,
 	},
+	{
+		"xkeysend",
+		json_xkeysend,
+	},
 };
 
 static struct command_result *handle_block_added(struct command *cmd,