fix(clipboard): carry block definitions across drawings on paste

Copying an INSERT and pasting it into another drawing rendered nothing:
the clipboard snapshotted referenced layers/linetypes/styles but not the
block definition itself, so the pasted reference pointed at a block the
target drawing didn't have.

Capture every block an copied INSERT references — walking nested INSERTs
transitively, skipping model/paper space and xref blocks — and store the
definition's base point plus its owned entities. On paste, recreate any
of those blocks the target drawing lacks via a new define_block_raw
(entities kept in block-local coordinates), before adding the pasted
references. Same-document pastes are unaffected since the blocks already
exist.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

src/app/cmd_result.rs

@@ -600,6 +600,9 @@ impl OpenCADStudio {
                     // Recreate any layer / linetype / style the copied entities
                     // need but this drawing lacks (cross-drawing paste). (#129)
                     self.merge_clipboard_deps(i);
+                    // …and any block definition the pasted INSERTs reference,
+                    // else a block reference renders empty. (#135)
+                    self.merge_clipboard_blocks(i);
                     let count = self.clipboard.len();
                     let new_handles: Vec<Handle> = self
                         .clipboard
@@ -1768,6 +1771,25 @@ impl OpenCADStudio {
         }
     }
 
+    /// Recreate any block definition the pasted INSERTs reference but tab
+    /// `i`'s document lacks (cross-drawing paste), so the block reference
+    /// renders its geometry instead of nothing. No-op for same-document
+    /// pastes. (#135)
+    pub(super) fn merge_clipboard_blocks(&mut self, i: usize) {
+        if self.clipboard_deps.blocks.is_empty() {
+            return;
+        }
+        let blocks = self.clipboard_deps.blocks.clone();
+        for def in blocks {
+            if self.tabs[i].scene.document.block_records.get(&def.name).is_some() {
+                continue;
+            }
+            self.tabs[i]
+                .scene
+                .define_block_raw(&def.name, def.base_point, def.entities);
+        }
+    }
+
     fn restore_pre_cmd_tangent(&mut self) {
         if let Some(was_on) = self.pre_cmd_tangent.take() {
             if !was_on {

src/app/mod.rs

@@ -651,6 +651,21 @@ pub struct ClipboardDeps {
     pub linetypes: Vec<acadrust::tables::LineType>,
     pub text_styles: Vec<acadrust::tables::TextStyle>,
     pub dim_styles: Vec<acadrust::tables::DimStyle>,
+    /// Block definitions the copied INSERTs reference (transitively),
+    /// snapshotted from the source drawing. Recreated on paste so a block
+    /// reference doesn't render empty in a drawing that lacks the
+    /// definition. (#135)
+    pub blocks: Vec<BlockDef>,
+}
+
+/// A captured block definition: its base point and the entities it owns
+/// (in block-local coordinates), minus the structural Block/BlockEnd
+/// markers which are rebuilt on paste.
+#[derive(Clone)]
+pub struct BlockDef {
+    pub name: String,
+    pub base_point: acadrust::types::Vector3,
+    pub entities: Vec<acadrust::EntityType>,
 }
 
 impl ClipboardDeps {
@@ -704,14 +719,70 @@ impl ClipboardDeps {
             linetypes: ltypes.iter().filter_map(|n| doc.line_types.get(n).cloned()).collect(),
             text_styles: tstyles.iter().filter_map(|n| doc.text_styles.get(n).cloned()).collect(),
             dim_styles: dstyles.iter().filter_map(|n| doc.dim_styles.get(n).cloned()).collect(),
+            blocks: Self::capture_blocks(doc, entities),
         }
     }
 
+    /// Snapshot every block definition the `entities` reference through an
+    /// INSERT, walking nested INSERTs transitively. Model/paper space and
+    /// xref blocks are skipped — those aren't portable definitions.
+    fn capture_blocks(doc: &acadrust::CadDocument, entities: &[acadrust::EntityType]) -> Vec<BlockDef> {
+        use acadrust::EntityType;
+        use rustc_hash::FxHashSet;
+        let mut seen: FxHashSet<String> = FxHashSet::default();
+        let mut queue: Vec<String> = Vec::new();
+        for e in entities {
+            if let EntityType::Insert(ins) = e {
+                if seen.insert(ins.block_name.clone()) {
+                    queue.push(ins.block_name.clone());
+                }
+            }
+        }
+        let mut defs = Vec::new();
+        while let Some(name) = queue.pop() {
+            let Some(br) = doc.block_records.get(&name) else {
+                continue;
+            };
+            if name.starts_with("*Model_Space")
+                || name.starts_with("*Paper_Space")
+                || br.flags.is_xref
+            {
+                continue;
+            }
+            let base_point = match doc.get_entity(br.block_entity_handle) {
+                Some(EntityType::Block(b)) => b.base_point,
+                _ => acadrust::types::Vector3::ZERO,
+            };
+            let mut owned = Vec::new();
+            for &eh in &br.entity_handles {
+                let Some(e) = doc.get_entity(eh) else {
+                    continue;
+                };
+                if matches!(e, EntityType::Block(_) | EntityType::BlockEnd(_)) {
+                    continue;
+                }
+                if let EntityType::Insert(ins) = e {
+                    if seen.insert(ins.block_name.clone()) {
+                        queue.push(ins.block_name.clone());
+                    }
+                }
+                owned.push(e.clone());
+            }
+            defs.push(BlockDef {
+                name,
+                base_point,
+                entities: owned,
+            });
+        }
+        defs
+    }
+
     pub fn is_empty(&self) -> bool {
         self.layers.is_empty()
             && self.linetypes.is_empty()
             && self.text_styles.is_empty()
             && self.dim_styles.is_empty()
+            && self.blocks.is_empty()
     }
 }
 

src/scene/mod.rs

@@ -3820,6 +3820,51 @@ impl Scene {
         Ok(())
     }
 
+    /// Recreate a block definition verbatim — the entities are already in
+    /// block-local coordinates (unlike `define_block_from_owned_entities`,
+    /// which folds in a base offset). No-op if the block already exists.
+    /// Used when pasting an INSERT whose block this drawing lacks. (#135)
+    pub fn define_block_raw(
+        &mut self,
+        name: &str,
+        base_point: acadrust::types::Vector3,
+        entities: Vec<EntityType>,
+    ) {
+        if name.is_empty() || self.document.block_records.get(name).is_some() {
+            return;
+        }
+        let next = self.document.next_handle();
+        let br_handle = Handle::new(next);
+        let block_handle = Handle::new(next + 1);
+        let end_handle = Handle::new(next + 2);
+
+        let mut block_record = acadrust::tables::BlockRecord::new(name);
+        block_record.handle = br_handle;
+        block_record.block_entity_handle = block_handle;
+        block_record.block_end_handle = end_handle;
+        if self.document.block_records.add(block_record).is_err() {
+            return;
+        }
+
+        let mut block = Block::new(name, base_point);
+        block.common.handle = block_handle;
+        block.common.owner_handle = br_handle;
+        let _ = self.document.add_entity(EntityType::Block(block));
+
+        let mut block_end = BlockEnd::new();
+        block_end.common.handle = end_handle;
+        block_end.common.owner_handle = br_handle;
+        let _ = self.document.add_entity(EntityType::BlockEnd(block_end));
+
+        for mut entity in entities {
+            Self::reset_clone_subhandles(&mut self.document, &mut entity);
+            entity.common_mut().handle = Handle::NULL;
+            entity.common_mut().owner_handle = br_handle;
+            let _ = self.document.add_entity(entity);
+        }
+        self.bump_geometry();
+    }
+
     fn synced_hatch_models(&self) -> Vec<HatchModel> {
         let layout_block = self.current_layout_block_handle();
         let hatch_offset = if self.current_layout == "Model" {