diff --git a/protobuf_definitions/control.proto b/protobuf_definitions/control.proto
index a9c02ef4..7d312654 100644
--- a/protobuf_definitions/control.proto
+++ b/protobuf_definitions/control.proto
@@ -261,3 +261,13 @@ message SetSotTargetCtrl {
 // Issue a command to clear the single-object tracking (SOT) target (stop tracking).
 message ClearSotTargetCtrl {
 }
+
+// Request to add an annotation to the current dive.
+//
+// Sent by the app when a diver picks a type from the in-dive command palette.
+// The drone stamps the authoritative time, publishes the result as an
+// AnnotationTel to every connected client, and writes it to the dive logfile, so
+// all clients converge on the same set. Fire-and-forget, like LightsCtrl.
+message AnnotationCtrl {
+  Annotation annotation = 1; // The annotation to record. The drone owns the timestamp, not this message.
+}
diff --git a/protobuf_definitions/message_formats.proto b/protobuf_definitions/message_formats.proto
index 76ca9869..130fdf11 100644
--- a/protobuf_definitions/message_formats.proto
+++ b/protobuf_definitions/message_formats.proto
@@ -1621,3 +1621,33 @@ message SotState {
   uint32 image_width = 3; // Width of the source frame in pixels.
   uint32 image_height = 4; // Height of the source frame in pixels.
 }
+
+// Origin of an annotation. Mirrors the AnnotationSource enum in Blueye Cloud.
+enum AnnotationSource {
+  ANNOTATION_SOURCE_UNSPECIFIED = 0; // Origin not specified.
+  ANNOTATION_SOURCE_CLOUD = 1; // Created in Blueye Cloud after the dive.
+  ANNOTATION_SOURCE_APP = 2; // Created in the app during the dive.
+  ANNOTATION_SOURCE_DRONE = 3; // Emitted by the drone itself.
+}
+
+// A single annotation added during a dive, e.g. by a diver tapping a type in the
+// app command palette, or emitted by the drone itself.
+//
+// Self-contained: it carries the type's display fields (name/icon/color) inline,
+// so the drone, any connected client, and the dive logfile can render it without
+// a separate catalog. The app keeps the full catalog locally (synced from
+// Blueye Cloud) to drive its palette, but only complete annotations go over the
+// wire. type_slug lets Blueye Cloud correlate the annotation to its type on import.
+//
+// The drone owns the timestamp: when this is logged the enclosing BinlogRecord
+// carries the time, like any other sample, so there is no time field here.
+message Annotation {
+  string type_slug = 1; // Stable type id for grouping / Cloud correlation. Empty for a free-form annotation.
+  string type_name = 2; // Type display name, e.g. "Hazard". Snapshot of the type at creation time.
+  string type_icon = 3; // Font Awesome solid icon name, kebab-case (e.g. "triangle-exclamation").
+  string type_color = 4; // Type color, RGB hex incl. leading '#', 7 chars (e.g. "#DC2626").
+  string title = 5; // Optional annotation title; Cloud falls back to type_name if empty. Max 200 chars.
+  string body = 6; // Optional free-form note. Unbounded.
+  google.protobuf.Duration duration = 7; // Optional span; omit for a point-in-time marker.
+  AnnotationSource source = 8; // Origin of the annotation; the app sets APP, the drone sets DRONE for its own.
+}
diff --git a/protobuf_definitions/telemetry.proto b/protobuf_definitions/telemetry.proto
index 1ed074e5..117187d3 100644
--- a/protobuf_definitions/telemetry.proto
+++ b/protobuf_definitions/telemetry.proto
@@ -362,3 +362,14 @@ message CameraPanTiltZoomTel {
 message SotStateTel {
   SotState sot_state = 1; // Current SOT state and bounding box.
 }
+
+// An annotation that now exists on the dive.
+//
+// Either added by a client (the drone echoes its AnnotationCtrl here, source APP)
+// or emitted by the drone itself (source DRONE); CLOUD is the post-dive Blueye
+// Cloud path and is not seen here. Published to every connected client and
+// written to the dive logfile. A late-joining client can fetch the most recent
+// one with GetTelemetryReq("AnnotationTel").
+message AnnotationTel {
+  Annotation annotation = 1; // The annotation that was added.
+}