diff --git a/meshexplorer/proto/meshexplorer/v1/chat.proto b/meshexplorer/proto/meshexplorer/v1/chat.proto
index 08aeb9f..3b6be7f 100644
--- a/meshexplorer/proto/meshexplorer/v1/chat.proto
+++ b/meshexplorer/proto/meshexplorer/v1/chat.proto
@@ -3,6 +3,7 @@ syntax = "proto3";
 package meshexplorer.v1;
 
 import "buf/validate/validate.proto";
+import "meshexplorer/v1/rules.proto";
 
 // One (origin, origin_pubkey, path, broker, topic) reception tuple.
 message OriginPathInfo {
@@ -41,12 +42,25 @@ message GetChatRequest {
     gte: 1
     lte: 1000
   }];
-  optional string before = 2;
-  optional string after = 3;
-  optional string channel_id = 4 [(buf.validate.field).string.pattern = "^[0-9A-Fa-f]+$"];
-  optional string region = 5;
+  // ClickHouse DateTime64 cursor, e.g. "2026-05-29 08:39:22.328".
+  optional string before = 2 [(buf.validate.field).string.(meshexplorer.v1.datetime64) = true];
+  optional string after = 3 [(buf.validate.field).string.(meshexplorer.v1.datetime64) = true];
+  optional string channel_id = 4 [(buf.validate.field).string = {
+    max_len: 2
+    pattern: "^[0-9A-Fa-f]+$"
+  }];
+  optional string region = 5 [(buf.validate.field).string.(meshexplorer.v1.region) = true];
   bool decrypt = 6;
-  repeated string private_keys = 7;
+  repeated string private_keys = 7 [(buf.validate.field).repeated = {
+    max_items: 50
+    items: {
+      string: {
+        min_len: 1
+        max_len: 64
+        pattern: "^[A-Za-z0-9+/=]+$"
+      }
+    }
+  }];
 }
 
 message GetChatResponse {
@@ -54,10 +68,22 @@ message GetChatResponse {
 }
 
 message StreamChatRequest {
-  optional string channel_id = 1 [(buf.validate.field).string.pattern = "^[0-9A-Fa-f]+$"];
-  optional string region = 2;
+  optional string channel_id = 1 [(buf.validate.field).string = {
+    max_len: 2
+    pattern: "^[0-9A-Fa-f]+$"
+  }];
+  optional string region = 2 [(buf.validate.field).string.(meshexplorer.v1.region) = true];
   bool decrypt = 3;
-  repeated string private_keys = 4;
+  repeated string private_keys = 4 [(buf.validate.field).repeated = {
+    max_items: 50
+    items: {
+      string: {
+        min_len: 1
+        max_len: 64
+        pattern: "^[A-Za-z0-9+/=]+$"
+      }
+    }
+  }];
   // Poll interval in ms (clamped 100..10000, default 1000).
   optional int32 poll_interval = 5 [(buf.validate.field).int32 = {
     gte: 100
diff --git a/meshexplorer/proto/meshexplorer/v1/map.proto b/meshexplorer/proto/meshexplorer/v1/map.proto
index 39a24a2..d57a7af 100644
--- a/meshexplorer/proto/meshexplorer/v1/map.proto
+++ b/meshexplorer/proto/meshexplorer/v1/map.proto
@@ -4,6 +4,7 @@ package meshexplorer.v1;
 
 import "buf/validate/validate.proto";
 import "meshexplorer/v1/common.proto";
+import "meshexplorer/v1/rules.proto";
 
 // Latest known position of a node. Mirrors unified_latest_nodeinfo rows
 // returned by getNodePositions().
@@ -19,6 +20,17 @@ message NodePosition {
 }
 
 message GetMapRequest {
+  option (buf.validate.message).cel = {
+    id: "bbox.lat_order"
+    message: "min_lat must be <= max_lat"
+    expression: "!has(this.min_lat) || !has(this.max_lat) || this.min_lat <= this.max_lat"
+  };
+  option (buf.validate.message).cel = {
+    id: "bbox.lng_order"
+    message: "min_lng must be <= max_lng"
+    expression: "!has(this.min_lng) || !has(this.max_lng) || this.min_lng <= this.max_lng"
+  };
+
   // Bounding box (decimal degrees). Unset fields mean "unbounded" on that edge.
   optional double min_lat = 1 [(buf.validate.field).double = {
     gte: -90
@@ -36,10 +48,18 @@ message GetMapRequest {
     gte: -180
     lte: 180
   }];
-  repeated string node_types = 5;
+  repeated string node_types = 5 [(buf.validate.field).repeated = {
+    max_items: 20
+    items: {
+      string: {
+        min_len: 1
+        max_len: 64
+      }
+    }
+  }];
   // Only include nodes seen within this many seconds.
   optional int32 last_seen = 6 [(buf.validate.field).int32.gte = 0];
-  optional string region = 7;
+  optional string region = 7 [(buf.validate.field).string.(meshexplorer.v1.region) = true];
   // When true, also compute and return the neighbor edge graph.
   bool include_neighbors = 8;
 }
diff --git a/meshexplorer/proto/meshexplorer/v1/neighbors.proto b/meshexplorer/proto/meshexplorer/v1/neighbors.proto
index fb6e189..72acc28 100644
--- a/meshexplorer/proto/meshexplorer/v1/neighbors.proto
+++ b/meshexplorer/proto/meshexplorer/v1/neighbors.proto
@@ -4,8 +4,20 @@ package meshexplorer.v1;
 
 import "buf/validate/validate.proto";
 import "meshexplorer/v1/common.proto";
+import "meshexplorer/v1/rules.proto";
 
 message GetAllNeighborsRequest {
+  option (buf.validate.message).cel = {
+    id: "bbox.lat_order"
+    message: "min_lat must be <= max_lat"
+    expression: "!has(this.min_lat) || !has(this.max_lat) || this.min_lat <= this.max_lat"
+  };
+  option (buf.validate.message).cel = {
+    id: "bbox.lng_order"
+    message: "min_lng must be <= max_lng"
+    expression: "!has(this.min_lng) || !has(this.max_lng) || this.min_lng <= this.max_lng"
+  };
+
   optional double min_lat = 1 [(buf.validate.field).double = {
     gte: -90
     lte: 90
@@ -22,9 +34,17 @@ message GetAllNeighborsRequest {
     gte: -180
     lte: 180
   }];
-  repeated string node_types = 5;
+  repeated string node_types = 5 [(buf.validate.field).repeated = {
+    max_items: 20
+    items: {
+      string: {
+        min_len: 1
+        max_len: 64
+      }
+    }
+  }];
   optional int32 last_seen = 6 [(buf.validate.field).int32.gte = 0];
-  optional string region = 7;
+  optional string region = 7 [(buf.validate.field).string.(meshexplorer.v1.region) = true];
 }
 
 message GetAllNeighborsResponse {
diff --git a/meshexplorer/proto/meshexplorer/v1/node.proto b/meshexplorer/proto/meshexplorer/v1/node.proto
index 8b85e94..888fd20 100644
--- a/meshexplorer/proto/meshexplorer/v1/node.proto
+++ b/meshexplorer/proto/meshexplorer/v1/node.proto
@@ -3,6 +3,7 @@ syntax = "proto3";
 package meshexplorer.v1;
 
 import "buf/validate/validate.proto";
+import "meshexplorer/v1/rules.proto";
 
 // Basic node identity/capabilities from the latest advert (getMeshcoreNodeInfo).
 message NodeInfo {
@@ -65,7 +66,7 @@ message MqttInfo {
 }
 
 message GetNodeRequest {
-  string public_key = 1 [(buf.validate.field).string.min_len = 10];
+  string public_key = 1 [(buf.validate.field).string.(meshexplorer.v1.hex64) = true];
   // Max number of recent adverts to return (default 50).
   optional int32 limit = 2 [(buf.validate.field).int32 = {
     gte: 1
@@ -96,7 +97,7 @@ message Neighbor {
 }
 
 message GetNodeNeighborsRequest {
-  string public_key = 1 [(buf.validate.field).string.min_len = 10];
+  string public_key = 1 [(buf.validate.field).string.(meshexplorer.v1.hex64) = true];
   optional int32 last_seen = 2 [(buf.validate.field).int32.gte = 0];
 }
 
@@ -107,7 +108,7 @@ message GetNodeNeighborsResponse {
 // One search request within a (possibly batched) SearchNodes call.
 message SearchQuery {
   optional string query = 1 [(buf.validate.field).string.max_len = 100];
-  optional string region = 2;
+  optional string region = 2 [(buf.validate.field).string.(meshexplorer.v1.region) = true];
   optional int32 last_seen = 3 [(buf.validate.field).int32.gte = 0];
   optional int32 limit = 4 [(buf.validate.field).int32 = {
     gte: 1
@@ -139,7 +140,10 @@ message SearchResultList {
 }
 
 message SearchNodesRequest {
-  repeated SearchQuery queries = 1 [(buf.validate.field).repeated.max_items = 500];
+  repeated SearchQuery queries = 1 [(buf.validate.field).repeated = {
+    min_items: 1
+    max_items: 500
+  }];
 }
 
 message SearchNodesResponse {
diff --git a/meshexplorer/proto/meshexplorer/v1/packets.proto b/meshexplorer/proto/meshexplorer/v1/packets.proto
index 407642e..4e0c0c3 100644
--- a/meshexplorer/proto/meshexplorer/v1/packets.proto
+++ b/meshexplorer/proto/meshexplorer/v1/packets.proto
@@ -3,6 +3,7 @@ syntax = "proto3";
 package meshexplorer.v1;
 
 import "buf/validate/validate.proto";
+import "meshexplorer/v1/rules.proto";
 
 // A raw mesh packet (meshcore_packets), hex fields kept as hex strings.
 message Packet {
@@ -21,7 +22,7 @@ message Packet {
 }
 
 message StreamPacketsRequest {
-  optional string region = 1;
+  optional string region = 1 [(buf.validate.field).string.(meshexplorer.v1.region) = true];
   // Payload type filter (0..15).
   optional int32 payload_type = 2 [(buf.validate.field).int32 = {
     gte: 0
@@ -32,7 +33,7 @@ message StreamPacketsRequest {
     gte: 0
     lte: 3
   }];
-  optional string origin_pubkey = 4 [(buf.validate.field).string.pattern = "^[0-9A-Fa-f]+$"];
+  optional string origin_pubkey = 4 [(buf.validate.field).string.(meshexplorer.v1.hex64) = true];
   // Poll interval in ms (clamped 100..10000, default 500).
   optional int32 poll_interval = 5 [(buf.validate.field).int32 = {
     gte: 100
diff --git a/meshexplorer/proto/meshexplorer/v1/rules.proto b/meshexplorer/proto/meshexplorer/v1/rules.proto
new file mode 100644
index 0000000..de3c06b
--- /dev/null
+++ b/meshexplorer/proto/meshexplorer/v1/rules.proto
@@ -0,0 +1,39 @@
+// proto2 syntax is required to extend protovalidate's rule messages (proto3
+// only permits extending options messages). protovalidate's own validate.proto
+// is proto2 for the same reason.
+syntax = "proto2";
+
+package meshexplorer.v1;
+
+import "buf/validate/validate.proto";
+
+// Reusable protovalidate string-rule "types" for this schema, so the same regex
+// isn't duplicated on every field. Apply with, e.g.,
+//   string public_key = 1 [(buf.validate.field).string.(meshexplorer.v1.hex64) = true];
+extend buf.validate.StringRules {
+  // A 32-byte meshcore key rendered as 64 hexadecimal characters
+  // (case-insensitive). Used for public keys / origin pubkeys, which are matched
+  // exactly in ClickHouse.
+  optional bool hex64 = 1001 [(buf.validate.predefined).cel = {
+    id: "string.hex64"
+    message: "must be 64 hexadecimal characters"
+    expression: "!rule || this.matches('^[0-9A-Fa-f]{64}$')"
+  }];
+
+  // A ClickHouse DateTime64 literal, e.g. "2026-05-29 08:39:22.328".
+  optional bool datetime64 = 1002 [(buf.validate.predefined).cel = {
+    id: "string.datetime64"
+    message: "must be a DateTime64 timestamp like \"YYYY-MM-DD HH:MM:SS[.fff]\""
+    expression: "!rule || this.matches('^[0-9]{4}-[0-9]{2}-[0-9]{2}[ T][0-9]{2}:[0-9]{2}:[0-9]{2}([.][0-9]+)?$')"
+  }];
+
+  // A region identifier (a config slug like "seattle", resolved server-side).
+  // Kept permissive on purpose — regions are config/lookup-driven, so this only
+  // bounds length and charset rather than enumerating values. Empty is allowed
+  // and means "no region filter".
+  optional bool region = 1003 [(buf.validate.predefined).cel = {
+    id: "string.region"
+    message: "must be a region identifier of at most 64 characters"
+    expression: "!rule || (size(this) <= 64 && this.matches('^[A-Za-z0-9._/-]*$'))"
+  }];
+}
diff --git a/meshexplorer/proto/meshexplorer/v1/stats.proto b/meshexplorer/proto/meshexplorer/v1/stats.proto
index abe7096..5a1848e 100644
--- a/meshexplorer/proto/meshexplorer/v1/stats.proto
+++ b/meshexplorer/proto/meshexplorer/v1/stats.proto
@@ -2,20 +2,23 @@ syntax = "proto3";
 
 package meshexplorer.v1;
 
+import "buf/validate/validate.proto";
+import "meshexplorer/v1/rules.proto";
+
 message GetTotalNodesRequest {
-  optional string region = 1;
+  optional string region = 1 [(buf.validate.field).string.(meshexplorer.v1.region) = true];
 }
 
 message GetNodesOverTimeRequest {
-  optional string region = 1;
+  optional string region = 1 [(buf.validate.field).string.(meshexplorer.v1.region) = true];
 }
 
 message GetPopularChannelsRequest {
-  optional string region = 1;
+  optional string region = 1 [(buf.validate.field).string.(meshexplorer.v1.region) = true];
 }
 
 message GetRepeaterPrefixesRequest {
-  optional string region = 1;
+  optional string region = 1 [(buf.validate.field).string.(meshexplorer.v1.region) = true];
 }
 
 message GetTotalNodesResponse {
diff --git a/meshexplorer/src/server/connect/validation.ts b/meshexplorer/src/server/connect/validation.ts
index ce98097..a5c77d5 100644
--- a/meshexplorer/src/server/connect/validation.ts
+++ b/meshexplorer/src/server/connect/validation.ts
@@ -1,10 +1,16 @@
 import type { DescMessage, MessageShape } from "@bufbuild/protobuf";
+import { createRegistry } from "@bufbuild/protobuf";
 import { createValidator } from "@bufbuild/protovalidate";
 import { Code, ConnectError, type Interceptor } from "@connectrpc/connect";
+import { file_meshexplorer_v1_rules } from "@/gen/meshexplorer/v1/rules_pb";
 
 // A single validator instance compiles and caches CEL programs per message
-// type, so reuse it across all requests.
-const validator = createValidator();
+// type, so reuse it across all requests. The registry carries our predefined
+// rule extensions (hex64, datetime64 in rules.proto); without it the validator
+// rejects those custom rules as unknown extensions.
+const validator = createValidator({
+  registry: createRegistry(file_meshexplorer_v1_rules),
+});
 
 function assertValid<Desc extends DescMessage>(schema: Desc, message: MessageShape<Desc>): void {
   const result = validator.validate(schema, message);