Replace is held G instead of Ctrl (Ctrl+W/Ctrl+D were hit while flying)

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

docs/DESIGN.md

@@ -81,7 +81,7 @@ Details and numbers live in the code and in `docs/systems/`.
     leave one open block below and a belt under that carries them off. F is optional upkeep: it
     cleans the trough, chips off slag and rakes the furnace grate. Short stubs stay for the next
     firing.
-  - Build actions: drag for lines, Shift-drag for rectangles, Ctrl to replace, hold C / X and
+  - Build actions: drag for lines, Shift-drag for rectangles, hold G to replace, hold C / X and
     drag to copy / cut, V to paste, Ctrl+Z to undo, middle mouse to pick,
     Shift+Q/E to switch build tabs.
 - **Economy:**
@@ -123,7 +123,7 @@ above, including:
 - **Copy and cut** are held keys, not a tool. Hold C or X and drag a box; it acts on release.
   Copy and cut look different. Cut is destructive, but it can be pasted back or undone.
 - **Ctrl+Z undoes building** (up to 80 steps). The bot building ghosts is never a step of its own.
-- **Holding Ctrl** while placing replaces what is built there.
+- **Holding Ctrl** while placing replaces what is built there (moved to G on 2026-10-23).
 - **Fans melt like copper (1085°C).** Put the fan outside the furnace, blowing in through a grate.
   The game warns when a fan gets close to melting.
 - **The vacuum takes only ticked materials** when anything is ticked, even if the drag starts on
@@ -144,7 +144,7 @@ above, including:
   the load above it stands still and the belt slips underneath; the top no longer slides over
   a stuck bottom. Filters still let their chosen materials drop through.
 - **Pick** (middle mouse) selects the piece under the cursor with its direction,
-  wall material and filter settings. G is unbound, as the owner requested.
+  wall material and filter settings. G no longer picks, as the owner requested (it is now Replace).
 - **The build menu** is a bar of tabs and icon tiles along the bottom: Structure, Moving,
   Liquids, Machines, Molds. Hover a tile for its full description, cost and placement help;
   gamepad players see the selected tile’s popup. The top-left card is hidden while building,
@@ -165,6 +165,8 @@ above, including:
   players will do it only when they need more ore rather than more money.
 - The project moved from a claude.ai artifact to local development with coding agents. It is
   built from small files, with `NOTES.md` as the owner's to-do inbox.
+- **Replace is held G, not Ctrl.** The owner hit the browser's Ctrl+W (close tab) and Ctrl+D
+  (bookmark) while replacing and flying with WASD, and the game ignored WASD while Ctrl was held.
 
 ## Ideas not built yet
 

docs/PROJECT_MAP.md

@@ -406,7 +406,7 @@ The selected tool and piece: R / Q / E, drill width, filter picker, the selectio
 Discovery cards, hover info (I) and the cursor label.
 - functions: showCard, howText, discoveryCard, reactionsOf, hoverInfo, renderInfo, drawCursorLabel
 
-### src/ui/input.js (75 lines)
+### src/ui/input.js (79 lines)
 Keyboard and mouse listeners.
 - functions: isTyping
 - variables: canvas

docs/agent-log.md

@@ -4,6 +4,21 @@ What agents have done, newest first. Add an entry for every piece of work: the d
 note or request it was for, what changed, the files touched, the tests run, and anything left
 open or not verified. Keep each entry short; the git history has the details.
 
+## 2026-10-23: Replace is held G, not Ctrl (Claude Code, with Codex)
+
+Note: "i see the issue was ctrl+w closing the tab… it happens for the bookmark hotkey too. maybe
+change the replace key?" The owner chose holding G.
+
+- `src/ui/input.js`: `GAME.ctrl` became `GAME.replace`, set while G is held. Ctrl no longer
+  does anything on its own, so WASD works while replacing. Ctrl+S, Ctrl+Z, Ctrl+wheel and the
+  leave-page prompt are unchanged.
+- Flag users and text: `previews.js`, `actions.js` ("Hold G to replace it."), `build-menu.js`
+  (Replace · G chip, key hints), `loop.js`, `state.js`, `notebook.js` controls, `docs/DESIGN.md`.
+- `test/play.py`: the replace checks hold G; a new check flies right with D while G is held
+  (121 checks pass). All 11 headless suites pass. `t_smooth.py`'s half-resolution check failed
+  on the slow fallback again (known, flaky under load).
+- Open: nothing.
+
 ## 2026-10-23: Ctrl+W no longer closes the game without asking (Claude Code)
 
 Note: "crash: hoplding crtl and pressing W crashes the whole browser."