feat(map-editor): v0.2.0c.1 — drag-paint strokes

LMB-hold strokes a line of paints (Auto-Tile: each hovered vertex;
Direct: each hovered cell as an override). RMB-hold strokes a line
of erases (clear_vertex / clear_override). On mouse-press inside the
UI (toolbar / palette / side-panel) the drag never enters paint-mode
so toolbar interaction stays unaffected.

State machine:
 - press(button) outside UI -> drag_paint = "paint"|"erase"
 - while drag_paint and corresponding button still down -> dispatch
   paint at current snap_vertex / mouse_cell each frame
 - button release -> drag_paint = nil

Idempotency: maps.set_vertex / set_override / clear_* are no-op when
the target state is unchanged, so the per-frame repaint is cheap and
doesn't grow the JSON on save.

init.lua

@@ -1,4 +1,4 @@
--- sporel-module-map-editor v0.2.0c
+-- sporel-module-map-editor v0.2.0c.1
 -- Interactive map editor — Rev 4 UX architecture (see design paper
 -- 2026-05-28-autotile-blob-styles-design.md §11 + plan stub
 -- 2026-05-28-map-editor-blob-v2.md). 0.2.0b adds the bottom palette
@@ -12,6 +12,9 @@
 -- {slot, rot, flip} on a material-bound terrain layer. Single
 -- `flip` flag (0/1) combined with rot (0..3) covers all 8 D4
 -- orientations; H+V buttons are redundant so we ship just one.
+-- 0.2.0c.1 adds drag-paint: LMB-hold strokes a line of paints, RMB-hold
+-- a line of erases (both in Auto-Tile and Direct mode). UI clicks on
+-- toolbar / palette / side-panel never enter drag-mode.
 -- Decal/Entity sub-selectors + Material-Properties modal land in 0.2.0d.
 --
 -- All editor logic in this single file: engine sandbox only allows
@@ -59,6 +62,7 @@ local state = (function()
         cheatsheet_open = false,            -- 0.2.0a: ?-modal toggled?
         mouse_cell      = nil,              -- {x, y} or nil if mouse off-map
         snap_vertex     = nil,              -- 0.2.0b: {vx, vy} or nil (auto-tile mode snap target)
+        drag_paint      = nil,              -- 0.2.0c.1: nil | "paint" | "erase" (active drag-stroke mode)
     }
 
     -- =====================================================================
@@ -147,6 +151,9 @@ local state = (function()
     end
     function M.get_snap_vertex()       return state.snap_vertex end
 
+    function M.set_drag_paint(mode)    state.drag_paint = mode end       -- 0.2.0c.1
+    function M.get_drag_paint()        return state.drag_paint end
+
     -- Used by tests to reset between asserts
     function M.reset()
         state.map_id = nil
@@ -162,6 +169,7 @@ local state = (function()
         state.cheatsheet_open = false
         state.mouse_cell = nil
         state.snap_vertex = nil
+        state.drag_paint = nil
         for name in pairs(state.layer_visible) do
             state.layer_visible[name] = true
         end
@@ -400,9 +408,10 @@ local ui = (function()
         { key="H",     action="Toggle tile flip 0<->1 (Direct-mode override)" },
         { key="0",     action="Reset transform (rot=0, flip=0)" },
         { key="Esc",   action="Quit editor" },
-        { key="LMB on canvas (Auto-Tile)", action="Paint vertex on active layer (any-corner fill)" },
+        { key="LMB-drag canvas (Auto-Tile)", action="Stroke-paint vertices (any-corner fill)" },
-        { key="RMB on canvas (Auto-Tile)", action="Clear vertex on active layer" },
+        { key="RMB-drag canvas (Auto-Tile)", action="Stroke-clear vertices" },
-        { key="LMB on canvas (Direct)",    action="Paint cell with active slot + rotation" },
+        { key="LMB-drag canvas (Direct)",    action="Stroke-paint cells (override with slot+rot+flip)" },
+        { key="RMB-drag canvas (Direct)",    action="Stroke-clear overrides" },
         { key="LMB on palette swatch",     action="Select slot (1-14) as active tile" },
         { key="RMB on Layer row",          action="Toggle layer visibility" },
         { key="LMB on Layer row",          action="Set as active layer" },
@@ -817,7 +826,7 @@ input.bind("toggle_cheatsheet", { "i" })     -- 0.2.0a — `i` for Info/help (no
 input.bind("flip",              { "h" })     -- 0.2.0c
 input.bind("reset_transform",   { "0" })     -- 0.2.0c
 
-engine.print("map-editor v0.2.0c: ready. Tab=mode, I=help, S=save, E=erase, R=rotate, H=flip, 0=reset, ESC=quit")
+engine.print("map-editor v0.2.0c.1: ready. Tab=mode, I=help, S=save, E=erase, R=rotate, H=flip, 0=reset, ESC=quit")
 
 -- =====================================================================
 -- Frame hooks
@@ -897,34 +906,52 @@ function update(ctx, dt)
         actions.reset_transform()
     end
 
-    -- Mouse clicks: hit-test UI first, then map area
+    -- Mouse clicks + drag: hit-test UI on press; if consumed we never
+    -- enter drag-mode for this stroke. Otherwise the press initiates a
+    -- drag-stroke whose paint/erase action repeats for every subsequent
+    -- snap_vertex (or cell) while the button stays down. set_vertex /
+    -- set_override are idempotent + no-op when state is unchanged so
+    -- repeating per-frame is cheap.
     if engine.input.was_mouse_pressed(engine.input.MOUSE_LEFT) then
         local consumed = ui.handle_click(mx, my, "left")
         if not consumed then
-            if state.get_mode() == "auto-tile" then
+            state.set_drag_paint("paint")
-                local snap = state.get_snap_vertex()
-                if snap then actions.paint_vertex_at(snap.vx, snap.vy, true) end
-            elseif state.get_mouse_cell() then
-                -- 0.2.0c: Direct-mode on a material-bound terrain layer
-                -- writes an override per cell, honouring active rot+flip.
-                local cell = state.get_mouse_cell()
-                actions.paint_override_at(cell.x, cell.y)
-            end
         end
     end
     if engine.input.was_mouse_pressed(engine.input.MOUSE_RIGHT) then
         local consumed = ui.handle_click(mx, my, "right")
         if not consumed then
+            state.set_drag_paint("erase")
+        end
+    end
+
+    -- Per-frame drag-paint dispatch (Auto-Tile uses snap_vertex; Direct
+    -- uses mouse_cell). Stops as soon as the originating button releases.
+    local dp = state.get_drag_paint()
+    if dp then
+        local lmb_down = engine.input.is_mouse_down(engine.input.MOUSE_LEFT)
+        local rmb_down = engine.input.is_mouse_down(engine.input.MOUSE_RIGHT)
+        local active = (dp == "paint" and lmb_down) or (dp == "erase" and rmb_down)
+        if not active then
+            state.set_drag_paint(nil)
+        else
             if state.get_mode() == "auto-tile" then
                 local snap = state.get_snap_vertex()
-                if snap then actions.paint_vertex_at(snap.vx, snap.vy, false) end
+                if snap then
-            elseif state.get_mouse_cell() then
+                    actions.paint_vertex_at(snap.vx, snap.vy, dp == "paint")
-                -- 0.2.0c: Direct + RMB on canvas clears the override.
+                end
+            else
                 local cell = state.get_mouse_cell()
+                if cell then
+                    if dp == "paint" then
+                        actions.paint_override_at(cell.x, cell.y)
+                    else
                         actions.erase_override_at(cell.x, cell.y)
                     end
                 end
             end
+        end
+    end
 
     camera.update(dt)
 end

manifest.module

@@ -1,6 +1,6 @@
 {
     "id": "map-editor",
-    "version": "0.2.0c",
+    "version": "0.2.0c.1",
     "kind": "module",
     "api": "^0.1",
     "ci_frames": 30,