gossip_store: add UUID entry at front of the store.

diff --git a/common/gossip_store.h b/common/gossip_store.h
index 013f8003..1545e868 100644
--- a/common/gossip_store.h
+++ b/common/gossip_store.h
@@ -15,7 +15,7 @@ struct gossip_rcvd_filter;
 /* First byte of file is the version.
  *
  * Top three bits mean incompatible change.
- * As of this writing, major == 0, minor == 15.
+ * As of this writing, major == 0, minor == 16.
  */
 #define GOSSIP_STORE_MAJOR_VERSION_MASK 0xE0
 #define GOSSIP_STORE_MINOR_VERSION_MASK 0x1F
diff --git a/connectd/gossip_store.c b/connectd/gossip_store.c
index 60da90f3..92298458 100644
--- a/connectd/gossip_store.c
+++ b/connectd/gossip_store.c
@@ -28,8 +28,9 @@ static size_t reopen_gossip_store(int *gossip_store_fd, const u8 *msg)
 {
 	u64 equivalent_offset;
 	int newfd;
+	u8 uuid[32];
 
-	if (!fromwire_gossip_store_ended(msg, &equivalent_offset))
+	if (!fromwire_gossip_store_ended(msg, &equivalent_offset, uuid))
 		status_failed(STATUS_FAIL_GOSSIP_IO,
 			      "Bad gossipd GOSSIP_STORE_ENDED msg: %s",
 			      tal_hex(tmpctx, msg));
diff --git a/devtools/dump-gossipstore.c b/devtools/dump-gossipstore.c
index 5280da86..c748d76c 100644
--- a/devtools/dump-gossipstore.c
+++ b/devtools/dump-gossipstore.c
@@ -7,13 +7,27 @@
 #include <common/utils.h>
 #include <fcntl.h>
 #include <gossipd/gossip_store_wiregen.h>
+#include <inttypes.h>
 #include <stdio.h>
 #include <unistd.h>
 #include <wire/peer_wire.h>
 
 /* Current versions we support */
 #define GSTORE_MAJOR 0
-#define GSTORE_MINOR 15
+#define GSTORE_MINOR 16
+
+/* Ended marker for <= 15 */
+static bool fromwire_gossip_store_ended_obs(const void *p, u64 *equivalent_offset)
+{
+	const u8 *cursor = p;
+	size_t plen = tal_count(p);
+
+	if (fromwire_u16(&cursor, &plen) != WIRE_GOSSIP_STORE_ENDED)
+		return false;
+ 	*equivalent_offset = fromwire_u64(&cursor, &plen);
+	return cursor != NULL;
+}
+
 
 static bool is_channel_announce(const u8 *msg, struct short_channel_id **scid)
 {
@@ -128,6 +142,8 @@ int main(int argc, char *argv[])
 		u8 *msg, *inner;
 		bool deleted, dying, complete;
 		u32 blockheight;
+		u64 offset;
+		u8 uuid[32];
 
 		deleted = (flags & GOSSIP_STORE_DELETED_BIT);
 		dying = (flags & GOSSIP_STORE_DYING_BIT);
@@ -184,6 +200,14 @@ int main(int argc, char *argv[])
 			printf("dying channel: %s (deadline %u)\n",
 			       fmt_short_channel_id(tmpctx, scid),
 			       blockheight);
+		} else if (fromwire_gossip_store_ended(msg, &offset, uuid)) {
+			printf("gossip store ended: offset %"PRIu64" in uuid %s\n",
+			       offset, tal_hexstr(tmpctx, uuid, sizeof(uuid)));
+		} else if (fromwire_gossip_store_ended_obs(msg, &offset)) {
+			printf("gossip store ended (v <= 15): offset %"PRIu64"\n",
+			       offset);
+		} else if (fromwire_gossip_store_uuid(msg, uuid)) {
+			printf("uuid %s\n", tal_hexstr(tmpctx, uuid, sizeof(uuid)));
 		} else {
 			printf("Unknown message %u: %s\n",
 			       fromwire_peektype(msg), tal_hex(msg, msg));
diff --git a/gossipd/gossip_store.c b/gossipd/gossip_store.c
index 075cb196..32c2ae7a 100644
--- a/gossipd/gossip_store.c
+++ b/gossipd/gossip_store.c
@@ -20,8 +20,8 @@
 #define GOSSIP_STORE_ZOMBIE_BIT_V13 0x1000U
 
 #define GOSSIP_STORE_TEMP_FILENAME "gossip_store.tmp"
-/* We write it as major version 0, minor version 14 */
-#define GOSSIP_STORE_VER ((0 << 5) | 15)
+/* We write it as major version 0, minor version 16 */
+#define GOSSIP_STORE_VER ((0 << 5) | 16)
 
 struct gossip_store {
 	/* Back pointer. */
@@ -85,10 +85,11 @@ static bool append_msg(int fd, const u8 *msg, u32 timestamp, u64 *len,
  * v13 removed private gossip entries
  * v14 removed zombie and spam flags
  * v15 added the complete flag
+ * v16 add uuid field, ended field uuid extension
  */
 static bool can_upgrade(u8 oldversion)
 {
-	return oldversion >= 9 && oldversion <= 14;
+	return oldversion >= 9 && oldversion <= 15;
 }
 
 /* On upgrade, do best effort on private channels: hand them to
@@ -355,7 +356,9 @@ rename_new:
 
 	/* Create end marker now new file exists. */
 	if (old_fd != -1) {
-		append_msg(old_fd, towire_gossip_store_ended(tmpctx, *total_len),
+		/* FIXME: real uuid! */
+		u8 uuid[32] = {0};
+		append_msg(old_fd, towire_gossip_store_ended(tmpctx, *total_len, uuid),
 			   0, &old_len, NULL);
 		close(old_fd);
 	}
diff --git a/gossipd/gossip_store_wire.csv b/gossipd/gossip_store_wire.csv
index b0f81c37..d371f9e8 100644
--- a/gossipd/gossip_store_wire.csv
+++ b/gossipd/gossip_store_wire.csv
@@ -23,7 +23,11 @@ msgdata,gossip_store_delete_chan,scid,short_channel_id,
 
 msgtype,gossip_store_ended,4105
 msgdata,gossip_store_ended,equivalent_offset,u64,
+msgdata,gossip_store_ended,uuid,u8,32
 
 msgtype,gossip_store_chan_dying,4106
 msgdata,gossip_store_chan_dying,scid,short_channel_id,
 msgdata,gossip_store_chan_dying,blockheight,u32,
+
+msgtype,gossip_store_uuid,4107
+msgdata,gossip_store_uuid,uuid,u8,32
diff --git a/tests/test_gossip.py b/tests/test_gossip.py
index d6b03dd0..b29f3b97 100644
--- a/tests/test_gossip.py
+++ b/tests/test_gossip.py
@@ -1207,7 +1207,7 @@ def test_gossip_store_load(node_factory):
 
     l1.start()
     # May preceed the Started msg waited for in 'start'.
-    wait_for(lambda: l1.daemon.is_in_log('Read 1/1/1/0 cannounce/cupdate/nannounce/delete from store in 800 bytes, now 778 bytes'))
+    wait_for(lambda: l1.daemon.is_in_log('Read 1/1/1/0 cannounce/cupdate/nannounce/delete from store in 832 bytes, now 778 bytes'))
     assert not l1.daemon.is_in_log('gossip_store.*truncating')
 
 
diff --git a/tools/lightning-downgrade.c b/tools/lightning-downgrade.c
index 2c76bf73..069ece08 100644
--- a/tools/lightning-downgrade.c
+++ b/tools/lightning-downgrade.c
@@ -168,7 +168,7 @@ static const char *downgrade_askrene_layers(const tal_t *ctx, struct db *db)
 
 static const struct db_version db_versions[] = {
 	{ "v25.09", 276, downgrade_askrene_layers, false },
-	{ "v25.12", 280, NULL, true },
+	{ "v25.12", 280, NULL, false },
 };
 
 static const struct db_version *version_db(const char *version)