feat(editor-core): wire CodegenState onto EditorState

Add pending_generate + pending_regenerate flags to CodegenState
(mirror of chat.pending_send). Wire codegen: CodegenState as a
field on EditorState immediately after chat, with TDD coverage in
codegen_state_defaults_to_idle_react.

crates/op-editor-core/src/codegen.rs

@@ -123,6 +123,11 @@ pub struct CodegenState {
     pub error: Option<String>,
     /// Frame at which "Copied" was shown, to time the transient label.
     pub copied_at: Option<u64>,
+    /// Set by the Code panel's Generate action; drained by the host codegen
+    /// session (P3). Mirror of `chat.pending_send`.
+    pub pending_generate: bool,
+    /// Set by Regenerate; drained by the host codegen session (P3).
+    pub pending_regenerate: bool,
 }
 
 impl Default for CodegenState {
@@ -137,6 +142,8 @@ impl Default for CodegenState {
             selection_snapshot: Vec::new(),
             error: None,
             copied_at: None,
+            pending_generate: false,
+            pending_regenerate: false,
         }
     }
 }
@@ -166,5 +173,7 @@ mod tests {
         assert!(s.code.is_empty());
         assert!(!s.degraded);
         assert!(s.error.is_none());
+        assert!(!s.pending_generate);
+        assert!(!s.pending_regenerate);
     }
 }

crates/op-editor-core/src/state.rs

@@ -40,6 +40,7 @@
 //! constructor is provided so the type is usable + testable.
 
 use crate::chat::ChatState;
+use crate::codegen::CodegenState;
 use crate::components::ComponentLibrary;
 use crate::editor_ui_state::EditorUiState;
 use crate::history::History;
@@ -81,6 +82,10 @@ pub struct EditorState {
     /// AI chat sub-state — message transcript, input draft, panel
     /// anchor, model catalog. Mirrors shell-core's `Document.chat`.
     pub chat: ChatState,
+    /// Code-generation sub-state — framework selection, phase,
+    /// progress, generated code, and pending-action flags. Read by
+    /// the Code panel painter; drained by the host codegen session.
+    pub codegen: CodegenState,
     /// Component library — reusable design-system subtrees. Mirrors
     /// shell-core's `Document.components`.
     pub components: ComponentLibrary,
@@ -108,6 +113,7 @@ impl EditorState {
             ui: UiDraftState::new(),
             editor_ui: EditorUiState::new(),
             chat: ChatState::default(),
+            codegen: CodegenState::default(),
             components,
             ui_kits: crate::uikit::builtin_kits(),
         }