M0: engine command registry, file formats, view math and CPU renderer

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

crates/engine/src/cmd/mod.rs

@@ -0,0 +1,116 @@
+//! The command registry. Ids follow Fusion's command ids where Fusion has the command; the
+//! toolbar placement (`tab`, `panel`) follows Fusion's Design workspace so the registry doubles
+//! as the parity metric (`cargo xtask parity`).
+
+mod edit;
+mod features;
+mod file;
+mod inspect;
+mod sketch;
+
+use serde::Serialize;
+use serde_json::Value;
+
+use crate::{Result, Session};
+
+pub type Run = fn(&mut Session, &Value) -> Result<Value>;
+pub type Enabled = fn(&Session) -> std::result::Result<(), String>;
+
+pub struct CommandSpec {
+    pub id: &'static str,
+    pub label: &'static str,
+    /// Toolbar tab (`SOLID`, `SKETCH`…); empty = not on the toolbar.
+    pub tab: &'static str,
+    /// Toolbar panel (`CREATE`, `MODIFY`…).
+    pub panel: &'static str,
+    /// Icon name for the UI (drawn in code).
+    pub icon: &'static str,
+    pub shortcut: Option<&'static str>,
+    /// One-line parameter documentation.
+    pub params: &'static str,
+    pub enabled: Enabled,
+    pub run: Run,
+    pub undoable: bool,
+}
+
+impl CommandSpec {
+    pub const fn new(id: &'static str, label: &'static str, run: Run) -> Self {
+        CommandSpec { id, label, tab: "", panel: "", icon: "", shortcut: None, params: "", enabled: always, run, undoable: true }
+    }
+    pub const fn at(mut self, tab: &'static str, panel: &'static str) -> Self {
+        self.tab = tab;
+        self.panel = panel;
+        self
+    }
+    pub const fn icon(mut self, i: &'static str) -> Self {
+        self.icon = i;
+        self
+    }
+    pub const fn key(mut self, k: &'static str) -> Self {
+        self.shortcut = Some(k);
+        self
+    }
+    pub const fn params(mut self, p: &'static str) -> Self {
+        self.params = p;
+        self
+    }
+    pub const fn enabled(mut self, e: Enabled) -> Self {
+        self.enabled = e;
+        self
+    }
+    pub const fn noundo(mut self) -> Self {
+        self.undoable = false;
+        self
+    }
+    pub fn info(&self, s: &Session) -> CommandInfo {
+        let e = (self.enabled)(s);
+        CommandInfo {
+            id: self.id,
+            label: self.label,
+            tab: self.tab,
+            panel: self.panel,
+            icon: self.icon,
+            shortcut: self.shortcut,
+            params: self.params,
+            enabled: e.is_ok(),
+            disabled_reason: e.err(),
+        }
+    }
+}
+
+#[derive(Clone, Debug, Serialize)]
+pub struct CommandInfo {
+    pub id: &'static str,
+    pub label: &'static str,
+    pub tab: &'static str,
+    pub panel: &'static str,
+    pub icon: &'static str,
+    pub shortcut: Option<&'static str>,
+    pub params: &'static str,
+    pub enabled: bool,
+    pub disabled_reason: Option<String>,
+}
+
+pub fn always(_: &Session) -> std::result::Result<(), String> {
+    Ok(())
+}
+
+pub fn in_sketch(s: &Session) -> std::result::Result<(), String> {
+    if s.active_sketch.is_some() { Ok(()) } else { Err("no sketch is being edited (Create Sketch or Edit Sketch first)".into()) }
+}
+
+/// Every command, in toolbar order.
+pub fn command_specs() -> Vec<&'static CommandSpec> {
+    let mut v: Vec<&'static CommandSpec> = Vec::new();
+    v.extend(sketch::COMMANDS.iter());
+    v.extend(features::COMMANDS.iter());
+    v.extend(edit::COMMANDS.iter());
+    v.extend(file::COMMANDS.iter());
+    v.extend(inspect::COMMANDS.iter());
+    v
+}
+
+pub fn find_command(id: &str) -> Option<&'static CommandSpec> {
+    let all = command_specs();
+    all.iter().find(|c| c.id == id).or_else(|| all.iter().find(|c| c.id.eq_ignore_ascii_case(id))).copied()
+}