Describe copy and paste of objects and nodes (#240)

- Scene editing: new section on Ctrl+C/Ctrl+V, where a paste lands
  and under which parent.
- Behaviors: a point on copying nodes and what the palette filter
  leaves out.
- Keyboard: Ctrl+C/Ctrl+V per tab and the picture import.
- Architecture: clipboard snapshot and paste commands.
- Development: e2e check total 1432.

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

Architecture.md

@@ -141,7 +141,10 @@ src/editor/            App → Editor (layout + ticker), PlaySession (the run),
                        snapshot may be made: only with everything saved, #231),
                        ProjectSettingsDialog + settingsChanges (name, the start-scene switch and the collision
                        layers in one dialog; the pure rule of what Apply has to carry out),
-                       EditorRun (run in editor), state, actions, shortcuts, debugHook (installs `window.__gm`;
+                       EditorRun (run in editor), state, actions, shortcuts, clipboard (#240: copy and paste of
+                       objects and graph pieces — where a paste lands, into which parent, what a graph may take;
+                       the snapshot is `core/model/clipboard`, the paste `core/commands/pasteCommands`),
+                       debugHook (installs `window.__gm`;
                        the hooks are grouped by area in debug/: ui, scene, graph, documents, pixel art, vector art,
                        render — `tools/` sees one flat object as before),
                        textProbe (finding widgets by their text — the ground floor of the test hook, shared with the sign-in screen),

Behaviors.md

@@ -314,6 +314,14 @@ playing use the same two words.
   (types are checked; a data input holds one link and is replaced), drag nodes, right-click a
   node or port to delete/disconnect, `Delete` removes the selection, wheel zooms. Everything is
   undoable.
+- **Copy and paste** (#240) works in every graph (behavior, state machine, shader, particles):
+  `Ctrl+C` or right-click → *Copy* takes the selected nodes, the links between them and the
+  groups and comments selected with them. `Ctrl+V` pastes under the pointer, or one grid step
+  beside the original when the pointer is elsewhere; the palette on empty canvas offers *Paste*
+  at the spot it was opened. A link to a node that was not copied stays behind. A node is pasted
+  only where the palette would offer it: a `State` never lands in a behavior, a behavior node
+  never in a shader, a second `Start`/`End` and a behavior calling itself are left out. What is
+  left out is named in a notice, the rest is pasted as one undo step and selected.
 - **Mouse and selection work as in the scene view.** The **middle button pans** from anywhere,
   a node under the pointer included (shift-drag on empty canvas does too); the left button never
   pans. Dragging on empty canvas pulls a **rubber band** instead, which selects every node it

Development.md

@@ -15,7 +15,7 @@ npm run build        # writes dist/ and regenerates index.html
 php tools/make-user.php <name> <password> [admin|user]        # an account; every tool signs in (see Accounts)
 php tests/php/accounts.test.php                               # the API's account rules, no server needed (CI's gate job)
 php tests/php/snapshots.test.php                              # the snapshot store (#231), the same way
-node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 1423 editor checks, screenshots in /tmp/gm-e2e-*.png
+node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 1432 editor checks, screenshots in /tmp/gm-e2e-*.png
 GM_STEPS=20 node tools/e2e.mjs                                # or 1-12, or 6,20 — a subset while working on one step
 ./e2e.sh start [GM_STEPS]                                     # the same run detached, see below
 ./e2e.sh status                                               # live progress, or the last run's result

Keyboard.md

@@ -1,8 +1,9 @@
 `Ctrl+Z` / `Ctrl+Shift+Z` / `Ctrl+Y` undo/redo (`Cmd` works wherever `Ctrl` does) · `Delete` or
 `Backspace` remove the selection (objects, nodes, frames, keys or a row of the Animation tab, a graph group or comment — the box only, its nodes stay, and a band that caught boxes and nodes together removes both in one step; an asset asks first) · `Ctrl+G` create
 container from the selection · `Ctrl+Enter` play, and pause/resume while playing · `Esc` stop ·
-`Ctrl+V` import an image from
-the clipboard as a texture (ignored while a text field has focus) · Animation tab: `Ctrl+C` copy
+`Ctrl+C` copy the selected objects or graph nodes, `Ctrl+V` paste them
+under the pointer ([Scene editing](Scene-editing), [Behaviors](Behaviors)) · `Ctrl+V` import an image from
+the clipboard as a texture when nothing copied fits the tab (ignored while a text field has focus) · Animation tab: `Ctrl+C` copy
 the picked keys, `Ctrl+V` paste them at the playhead (while keys are copied this takes `Ctrl+V`
 there, so an image is pasted from another tab), `Ctrl`+drag duplicate keys · `Tab` / `Shift+Tab` cycle fields · lists: `↑`/`↓` move,
 `←`/`→` fold, `Enter` activates · number

Scene-editing.md

@@ -155,7 +155,28 @@ so they cannot drift apart. Only *Expand all* / *Collapse all* stay in the panel
 something. Which object the menu is for follows the rule of a press: a selected object under the
 pointer, hidden behind others or not, keeps the selection, and the menu acts on all of it;
 otherwise the topmost object there is selected first. Empty space, an empty tilemap cell
-included, opens no menu. The Container tab does the same for its template.
+included, opens a menu with *Paste* alone. The Container tab does the same for its template.
+
+**Copy and paste (#240).** `Ctrl+C` copies the selected objects, each with everything below it
+(children, colliders, rigidbodies), and `Ctrl+V` pastes them into the scene or container the
+visible tab shows. The object menu offers the same as *Copy* and *Paste*. The copy keeps names,
+overrides and the look (rotation, scale, mirror); the editor offset stays behind. A placed
+container is copied as a placed container and keeps showing its template, content picked out
+of one is pasted as ordinary objects. The clipboard is the editor's own and holds ids of this
+project, so it lives until another project is opened.
+
+- **Where it lands:** under the pointer when the pointer is over the view (the copied group
+  keeps its layout, centred there), else one grid step (100) down and right of the original, and
+  another step for every earlier paste that is still there.
+- **Into which parent:** into the one selected object (from the menu: the one clicked). When that
+  object is an original or an earlier paste, the copy goes beside it instead, under its parent, so
+  pasting again and again never stacks copies inside each other. Without such an object the copy
+  keeps the parent it had, if this scene or container has it, else it goes to the top level. It
+  keeps its look under the new parent, as a re-parent does.
+- **Refused:** a container pasted into its own template (or into anything it ends up inside),
+  with the notice a drop gets. One paste is one undo step and selects what it pasted.
+- While objects are copied, `Ctrl+V` in the Scene and Container tab pastes them; an image from
+  the system clipboard is then pasted from another tab. With nodes copied it goes through there.
 
 **Editor offset (scene view only).** Every scene object additionally carries an
 `editorOffset` — an x/y shift of where it is *drawn, selected and dragged* in the Scene tab,