diff --git a/crates/ui-egui/src/comments_tests.rs b/crates/ui-egui/src/comments_tests.rs
index 696ff322..eea2278e 100644
--- a/crates/ui-egui/src/comments_tests.rs
+++ b/crates/ui-egui/src/comments_tests.rs
@@ -7,7 +7,7 @@ use egui::{Event, Key, Modifiers, Pos2, pos2, vec2};
 use figcraft_engine::Session;
 use serde_json::{Value, json};
 
-use crate::comments::{cluster, insert_mention, mention_matches, mention_query};
+use crate::comments::{cluster, insert_mention, mention_matches, mention_query, start_draft};
 use crate::present_tests::{Ui, id};
 
 fn add(s: &mut Session, x: f64, y: f64, text: &str, author: &str) -> u64 {
@@ -41,6 +41,35 @@ fn comments(u: &Ui) -> Value {
     u.app.inspect()["comments"].clone()
 }
 
+#[test]
+fn switching_from_comment_to_move_closes_the_unposted_composer() {
+    let mut u = Ui::new(Session::new());
+    u.app.run("tool.set", json!({"tool": "comment"}));
+    start_draft(&mut u.app, 100.0, 80.0);
+    assert!(comments(&u)["draft"].is_array());
+
+    u.app.run("tool.set", json!({"tool": "move"}));
+    u.frame(vec![]);
+    assert!(comments(&u)["draft"].is_null());
+}
+
+#[test]
+fn control_channel_tool_switch_closes_the_unposted_composer() {
+    let mut u = Ui::new(Session::new());
+    u.app.run("tool.set", json!({"tool": "comment"}));
+    start_draft(&mut u.app, 100.0, 80.0);
+    assert!(comments(&u)["draft"].is_array());
+
+    let invalid = json!({"command": "tool.set", "params": {"tool": "not-a-tool"}});
+    assert!(crate::control::handle(&mut u.app, &egui::Context::default(), "engine.execute", &invalid).is_err());
+    assert!(comments(&u)["draft"].is_array());
+
+    crate::control::handle(&mut u.app, &egui::Context::default(), "engine.execute", &json!({"command": "tool.set", "params": {"tool": "move"}}))
+        .unwrap();
+    u.frame(vec![]);
+    assert!(comments(&u)["draft"].is_null());
+}
+
 #[test]
 fn mention_helpers() {
     // The `@query` before the cursor.
diff --git a/crates/ui-egui/src/control.rs b/crates/ui-egui/src/control.rs
index a4a8dd15..2d35609a 100644
--- a/crates/ui-egui/src/control.rs
+++ b/crates/ui-egui/src/control.rs
@@ -239,6 +239,7 @@ pub fn handle(app: &mut FigApp, ctx: &Context, method: &str, p: &Value) -> Resul
             let cmd = p.get("command").and_then(Value::as_str).ok_or("`command` required")?;
             let params = p.get("params").cloned().unwrap_or(json!({}));
             let r = app.session.execute(cmd, &params).map_err(|e| e.to_string());
+            app.clear_comment_draft_after_tool_set(cmd, r.is_ok());
             // Programmatic calls never open dialogs.
             app.session.ui_requests.retain(|u| !u.kind.starts_with("dialog."));
             app.handle_ui_requests();
diff --git a/crates/ui-egui/src/lib.rs b/crates/ui-egui/src/lib.rs
index 072aec62..d728dc27 100644
--- a/crates/ui-egui/src/lib.rs
+++ b/crates/ui-egui/src/lib.rs
@@ -831,9 +831,17 @@ impl FigApp {
         }
     }
 
+    /// Dismiss the composer after a successful switch away from the Comment tool.
+    pub(crate) fn clear_comment_draft_after_tool_set(&mut self, id: &str, succeeded: bool) {
+        if id == "tool.set" && succeeded && self.session.tool.tool != figcraft_engine::tools::ToolId::Comment {
+            self.ui.comments.draft = None;
+        }
+    }
+
     /// Run a command, surfacing errors as a toast. Returns the result.
     pub fn run(&mut self, id: &str, params: Value) -> Option<Value> {
         let r = self.session.execute(id, &params);
+        self.clear_comment_draft_after_tool_set(id, r.is_ok());
         self.handle_ui_requests();
         r.map_err(|e| self.failed(id, &e)).ok()
     }