Surface toolset: icons and planned commands (#808)

Icons for the surface toolset, and its planned commands registered and disabled with the issue that tracks each one.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/engine/src/cmd/mod.rs

@@ -9,6 +9,17 @@ macro_rules! created_doc {
     };
 }
 
+/// A command that is designed and registered (id, toolbar place, icon, params doc) but not built
+/// yet. It is disabled with the reason, so the toolbar greys it and says why, and its `run`
+/// refuses too, however it is reached. `$issue` is the GitHub issue that tracks building it.
+macro_rules! planned {
+    ($id:literal, $label:literal, $issue:literal) => {
+        CommandSpec::new($id, $label, |_, _| Err(crate::EngineError::Other(concat!("not supported yet: ", $label, " (issue #", $issue, ")").into())))
+            .enabled(|_| Err(concat!("not supported yet (issue #", $issue, ")").into()))
+            .planned($issue)
+    };
+}
+
 mod browser;
 mod clipboard;
 mod component;
@@ -89,6 +100,8 @@ pub struct CommandSpec {
     /// Reads the evaluated model (the default). A command that reads only the document and the
     /// session's history runs on a model left stale by a live gesture without evaluating it first.
     pub reads_model: bool,
+    /// Registered but not built yet (see `planned!`): the GitHub issue number that tracks it.
+    pub planned: Option<&'static str>,
 }
 
 impl CommandSpec {
@@ -106,8 +119,14 @@ impl CommandSpec {
             undoable: true,
             live: None,
             reads_model: true,
+            planned: None,
         }
     }
+    /// Not built yet; `issue` tracks building it.
+    pub const fn planned(mut self, issue: &'static str) -> Self {
+        self.planned = Some(issue);
+        self
+    }
     /// Takes `live: true`, run by `run`.
     pub const fn live(mut self, run: LiveRun) -> Self {
         self.live = Some(run);
@@ -161,6 +180,7 @@ impl CommandSpec {
             params: self.params,
             enabled: e.is_ok(),
             disabled_reason: e.err(),
+            planned: self.planned,
         }
     }
 }
@@ -176,6 +196,8 @@ pub struct CommandInfo {
     pub params: &'static str,
     pub enabled: bool,
     pub disabled_reason: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub planned: Option<&'static str>,
 }
 
 pub fn always(_: &Session) -> std::result::Result<(), String> {