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diff --git a/docs/superpowers/specs/2026-04-05-demos-design.md b/docs/superpowers/specs/2026-04-05-demos-design.md
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-# Downstroke Demo Games Design
-
-**Date:** 2026-04-05
-**Status:** Approved
-**Scope:** `demo/` folder, 5 demo games, Makefile `make demos` target, CLAUDE.md update
-
----
-
-## Goal
-
-Provide 5 small self-contained demo games in `demo/` that collectively exercise every engine system. Each demo compiles to its own executable (`bin/demo-*`). They replace the macroknight integration test for Milestone 8 and serve as living documentation of the engine API.
-
----
-
-## File Layout
-
-```
-demo/
-  assets/                        ← copied from macroknight/assets (not symlinked)
-    monochrome-transparent.png   ← tileset spritesheet
-    monochrome_transparent.tsx   ← tileset metadata (TSX)
-    level-0.tmx                  ← level used by platformer, topdown, sandbox
-    DejaVuSans.ttf               ← font for audio demo text
-    jump.wav                     ← sound effect (platformer jump, shmup shoot)
-    theme.ogg                    ← music (audio demo)
-  platformer.scm
-  shmup.scm
-  topdown.scm
-  audio.scm
-  sandbox.scm
-```
-
-**Omitted from copy:** `prefabs.scm`, `macroknight.tiled-project`, `macroknight.tiled-session` — macroknight-specific files not needed by any demo.
-
----
-
-## Build
-
-### Makefile additions
-
-```makefile
-DEMO_NAMES := platformer shmup topdown audio sandbox
-DEMO_BINS  := $(patsubst %,bin/demo-%,$(DEMO_NAMES))
-
-demos: engine $(DEMO_BINS)
-
-bin/demo-%: demo/%.scm $(OBJECT_FILES) | bin
-	csc demo/$*.scm $(OBJECT_FILES) -o bin/demo-$* -I bin
-```
-
-- `make` — builds engine modules only (unchanged)
-- `make demos` — builds all 5 demo executables; depends on engine being built first
-- Demos are compiled as programs (not units), linked against all engine `.o` files
-
-### CLAUDE.md update
-
-Add to the Build & Test section:
-
-> `make demos` must always succeed. A demo that fails to compile is a build failure. Run `make && make demos` to verify both engine and demos build cleanly.
-
----
-
-## Demo Code Pattern
-
-Every demo follows this ~30-line structure:
-
-```scheme
-(import (prefix sdl2 "sdl2:")
-        (prefix sdl2-ttf "ttf:")
-        (prefix sdl2-image "img:")
-        downstroke/engine
-        downstroke/world
-        downstroke/tilemap
-        downstroke/renderer
-        downstroke/input
-        downstroke/physics
-        downstroke/assets)
-
-(define *game*
-  (make-game
-    title: "Demo: <Name>" width: 600 height: 400
-    preload: (lambda (game) ...)   ;; load tilemap, tileset texture, sounds
-    create:  (lambda (game) ...)   ;; build scene, place entities
-    update:  (lambda (game dt) ...)  ;; input dispatch, physics calls
-    render:  (lambda (game) ...)))   ;; HUD overlay (optional)
-
-(game-run! *game*)
-```
-
-Tile IDs in entity plists are placeholder values — to be adjusted visually after first run.
-
----
-
-## The 5 Demos
-
-### 1. `demo/platformer.scm` — Platformer
-
-**Systems exercised:** `input`, `physics` (gravity + tile collision), `renderer` (tilemap + entities), `world`/scene, camera follow, audio (sound effect)
-
-**Mechanics:**
-- Player entity with gravity, left/right movement, jump
-- Tile collision via `apply-physics` from `physics.scm`
-- Camera follows player horizontally
-- Jump sound via macroknight's `sound.scm` (or direct SDL_mixer call)
-- Level: `demo/assets/level-0.tmx`
-- Tile IDs: placeholder (user adjusts)
-
-**Key entity plist:**
-```scheme
-(list #:type 'player
-      #:x 100 #:y 50
-      #:width 16 #:height 16
-      #:vx 0 #:vy 0
-      #:gravity? #t
-      #:on-ground? #f
-      #:tile-id 1)
-```
-
-**Update logic:** read input → set `#:vx` from left/right → jump sets `#:vy` → call physics step → update camera x to follow player x.
-
----
-
-### 2. `demo/shmup.scm` — Shoot-em-up
-
-**Systems exercised:** `entity` (spawning/removal), entity-entity collision via `physics.scm`, `input`, `renderer`, `world`/scene (no tilemap)
-
-**Mechanics:**
-- Player ship at bottom, moves left/right
-- Space bar fires bullet upward (new entity added to scene)
-- Enemies spawn from top at random x positions every N frames, move downward
-- Bullet-enemy collision: both entities removed from scene
-- No tilemap — plain background (black/SDL clear)
-- No gravity on any entity
-- `jump.wav` plays on shoot
-
-**Key entity plists:**
-```scheme
-;; player
-(list #:type 'player #:x 280 #:y 360 #:width 16 #:height 16 #:vx 0 #:vy 0 #:tile-id 2)
-;; bullet
-(list #:type 'bullet #:x px #:y 340 #:width 4 #:height 8 #:vx 0 #:vy -5 #:tile-id 3)
-;; enemy
-(list #:type 'enemy  #:x rx #:y 0   #:width 16 #:height 16 #:vx 0 #:vy 2 #:tile-id 4)
-```
-
-**Update logic:** move entities by vx/vy each frame → AABB collision check between bullets and enemies → filter dead entities from scene → spawn new enemy every 60 frames → read input for player movement and shoot.
-
----
-
-### 3. `demo/topdown.scm` — Top-down explorer
-
-**Systems exercised:** `input` (8-directional), `renderer` (tilemap + entity), `world`/scene, camera follow (both axes), `physics` (no gravity)
-
-**Mechanics:**
-- Player entity moves in 8 directions (WASD or arrows)
-- No gravity (`#:gravity? #f`)
-- Camera follows player on both x and y axes
-- Level: `demo/assets/level-0.tmx` (same tilemap, different movement feel)
-- No audio
-
-**Update logic:** read input → set `#:vx` and `#:vy` from direction keys → apply tile collision (no gravity component) → update camera to center on player.
-
----
-
-### 4. `demo/audio.scm` — Audio showcase
-
-**Systems exercised:** audio (sound effects + music), `renderer` (text via `draw-ui-text`), `input`, `assets`
-
-**Mechanics:**
-- Static screen with text instructions rendered via `draw-ui-text`
-- Press **J** → play `jump.wav`
-- Press **M** → toggle `theme.ogg` music on/off
-- Press **Escape** → quit
-- No tilemap, no physics, no moving entities
-- Uses `DejaVuSans.ttf` for text
-- Audio calls via macroknight's `sound.scm` functions (`load-sounds!`, `play-sound!`, `load-music!`, `play-music!`, `stop-music!`) — or direct SDL_mixer FFI if sound.scm is not available
-
-**Display:** colored rectangle background + text labels for each key binding.
-
----
-
-### 5. `demo/sandbox.scm` — Physics sandbox
-
-**Systems exercised:** `physics` (gravity + tile collision + entity-entity collision), `renderer`, `world`/scene, no player input
-
-**Mechanics:**
-- 10 entities spawned at random x positions near the top of the screen
-- All have `#:gravity? #t`
-- Physics step runs each frame (gravity accelerates, tile collision stops them)
-- Entities rest on floor tiles or bounce (depending on physics.scm behavior)
-- No player — pure observation of physics pipeline
-- Level: `demo/assets/level-0.tmx`
-- After all entities settle (or after 10 seconds), loop: despawn all, respawn at new random positions
-
----
-
-## Systems Coverage Matrix
-
-| System / Module | platformer | shmup | topdown | audio | sandbox |
-|---|---|---|---|---|---|
-| `engine` (make-game, game-run!) | ✓ | ✓ | ✓ | ✓ | ✓ |
-| `input` | ✓ | ✓ | ✓ | ✓ | — |
-| `physics` (gravity) | ✓ | — | — | — | ✓ |
-| `physics` (tile collision) | ✓ | — | ✓ | — | ✓ |
-| `physics` (entity collision) | — | ✓ | — | — | ✓ |
-| `renderer` (tilemap) | ✓ | — | ✓ | — | ✓ |
-| `renderer` (entities) | ✓ | ✓ | ✓ | — | ✓ |
-| `renderer` (text) | — | — | — | ✓ | — |
-| `world` / scene | ✓ | ✓ | ✓ | — | ✓ |
-| `assets` registry | ✓ | ✓ | ✓ | ✓ | ✓ |
-| audio (sound) | ✓ | ✓ | — | ✓ | — |
-| audio (music) | — | — | — | ✓ | — |
-| camera follow | ✓ (x) | — | ✓ (xy) | — | — |
-
----
-
-## Out of Scope
-
-- Animation state machine (`animation.scm`) — not yet extracted to downstroke
-- AI (`ai.scm`) — not yet extracted
-- Prefab system — not yet extracted
-- Scene transitions — Milestone 9
-- Asset-type-specific load helpers (`game-load-tilemap!` etc.) — Milestone 6
diff --git a/docs/superpowers/specs/2026-04-05-milestone-8-game-object-lifecycle-design.md b/docs/superpowers/specs/2026-04-05-milestone-8-game-object-lifecycle-design.md
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-# Milestone 8 — The Game Object and Lifecycle API
-
-**Date:** 2026-04-05
-**Status:** Approved
-**Scope:** `engine.scm`, `assets.scm`, macroknight port
-**Milestone numbering:** Follows `downstroke.org` / `TODO-engine.org` (Milestone 8). CLAUDE.md refers to the same work as "Milestone 7".
-
----
-
-## Goal
-
-Introduce `make-game` and `game-run!` as the public entry point for downstroke. A minimal game becomes ~20 lines of Scheme. This is the "Phaser moment" — the API stabilises around a game struct with lifecycle hooks.
-
----
-
-## Architecture
-
-Two new files:
-
-- **`engine.scm`** — `make-game` struct, `game-run!`, the frame loop, and all public accessors.
-- **`assets.scm`** — minimal key→value asset registry. No asset-type-specific logic; that is Milestone 6's domain.
-
-`engine.scm` imports: `renderer.scm`, `input.scm`, `world.scm`, `assets.scm`, the sdl2 egg (prefix `sdl2:`), `sdl2-ttf` (prefix `ttf:`), and `sdl2-image` (prefix `img:`).
-
-**Audio / mixer is not initialised by the engine in this milestone.** `mixer.scm` and `sound.scm` remain in macroknight and are not yet extracted. macroknight's `preload:` hook calls `init-audio!` directly from `sound.scm` until those modules are extracted.
-
-`physics.scm` is **not** imported by the engine. Physics is a library; the user requires it if needed and calls physics functions from their `update:` hook.
-
-### New function in `renderer.scm`
-
-`render-scene!` does not yet exist. It must be added to `renderer.scm` as part of this milestone. The module uses `export *` so no explicit export update is needed.
-
-Existing signatures in `renderer.scm` that `render-scene!` calls:
-- `(draw-tilemap renderer camera tileset-texture tilemap)` — 4 args
-- `(draw-entities renderer camera tileset tileset-texture entities)` — 5 args
-- `tilemap-tileset` is a field accessor on the `tilemap` struct (defined in `tilemap.scm`)
-
-```scheme
-(define (render-scene! renderer scene)
-  (let ((camera          (scene-camera scene))
-        (tilemap         (scene-tilemap scene))
-        (tileset-texture (scene-tileset-texture scene))
-        (tileset         (tilemap-tileset (scene-tilemap scene)))
-        (entities        (scene-entities scene)))
-    (draw-tilemap renderer camera tileset-texture tilemap)
-    (draw-entities renderer camera tileset tileset-texture entities)))
-```
-
-### Build order (Makefile)
-
-Only modules that currently exist in downstroke are listed. Modules still in macroknight (`animation`, `ai`, `prefabs`, `mixer`, `sound`) are not prerequisites for this milestone.
-
-```
-entity → tilemap → world → input → renderer → assets → engine
-```
-
-`physics` is not a link dependency of `engine` and is omitted from this chain. It is a separate build target.
-
----
-
-## Data Structures
-
-### `game` struct (`engine.scm`)
-
-`defstruct` is called with `constructor: make-game*` so the generated raw constructor does not collide with the public keyword constructor `make-game`.
-
-```scheme
-(defstruct (game constructor: make-game*)
-  title width height
-  window renderer
-  input                ;; input-state record (accessor: game-input)
-  input-config         ;; input-config record (accessor: game-input-config)
-  assets               ;; asset registry hash table (from assets.scm)
-  frame-delay
-  preload-hook         ;; (lambda (game) ...)
-  create-hook          ;; (lambda (game) ...)
-  update-hook          ;; (lambda (game dt) ...)
-  render-hook          ;; (lambda (game) ...) — post-render overlay
-  scene)               ;; current scene struct (accessor: game-scene)
-```
-
-**Note:** There is no separate `camera` field. The camera lives inside the scene (`scene-camera`). `game-camera` is a convenience accessor (see Accessors section).
-
-### `make-game` keyword constructor
-
-```scheme
-(define (make-game #!key
-    (title "Downstroke Game")
-    (width 640) (height 480)
-    (frame-delay 16)
-    (input-config *default-input-config*)
-    (preload #f) (create #f) (update #f) (render #f))
-  (make-game*
-    title: title width: width height: height
-    window: #f renderer: #f scene: #f
-    input: (create-input-state input-config)  ;; create-input-state takes one arg: config
-    input-config: input-config
-    assets: (make-asset-registry)
-    frame-delay: frame-delay
-    preload-hook: preload
-    create-hook: create
-    update-hook: update
-    render-hook: render))
-```
-
-### Asset registry (`assets.scm`)
-
-```scheme
-(define (make-asset-registry)    (make-hash-table))
-(define (asset-set! reg key val) (hash-table-set! reg key val))
-(define (asset-ref reg key)      (hash-table-ref reg key (lambda () #f)))
-```
-
----
-
-## Lifecycle: `game-run!`
-
-```scheme
-(define (game-run! game)
-  ;; 1. SDL2 init (no audio — mixer not yet extracted, user calls init-audio! in preload:)
-  (sdl2:init! '(video joystick game-controller))
-  (ttf:init!)
-  (img:init! '(png))
-
-  ;; 2. Create window + renderer
-  (game-window-set! game
-    (sdl2:create-window! (game-title game) 'centered 'centered
-                         (game-width game) (game-height game) '()))
-  (game-renderer-set! game
-    (sdl2:create-renderer! (game-window game) -1 '(accelerated vsync)))
-
-  ;; 3. preload hook
-  (when (game-preload-hook game) ((game-preload-hook game) game))
-
-  ;; 4. create hook
-  (when (game-create-hook game) ((game-create-hook game) game))
-
-  ;; 5. Frame loop
-  (let loop ((last-ticks (sdl2:get-ticks)))
-    (let* ((now    (sdl2:get-ticks))
-           (dt     (- now last-ticks))
-           (events (sdl2:collect-events!))
-           (input  (input-state-update (game-input game) events (game-input-config game))))
-      (game-input-set! game input)
-      (unless (input-held? input 'quit)
-        (when (game-update-hook game) ((game-update-hook game) game dt))
-        (sdl2:render-clear! (game-renderer game))
-        (when (game-scene game)
-          (render-scene! (game-renderer game) (game-scene game)))
-        (when (game-render-hook game) ((game-render-hook game) game))
-        (sdl2:render-present! (game-renderer game))
-        (sdl2:delay! (game-frame-delay game))
-        (loop now))))
-
-  ;; 6. Cleanup
-  (sdl2:destroy-window! (game-window game))
-  (sdl2:quit!))
-```
-
-**Notes:**
-- `sdl2:collect-events!` pumps the SDL2 event queue and returns a list of events (from the sdl2 egg).
-- `input-state-update` is the existing function in `input.scm`: `(input-state-update state events config)`. It is purely functional — it returns a new `input-state` record and does not mutate the existing one.
-- `create-input-state` in `input.scm` takes one argument: `(create-input-state config)` — it initialises all actions to `#f`.
-- Quit is detected via `(input-held? input 'quit)` — the `'quit` action is in `*default-input-config*` mapped to `escape` key: `(escape . quit)` in `keyboard-map`.
-- `sdl2:render-clear!` and `sdl2:render-present!` are called directly from the sdl2 egg (no wrapper needed).
-- The loop exits when `input-held?` returns true for `'quit`. No user-settable `game-running?` flag in this milestone.
-
----
-
-## `render:` Hook Semantics
-
-Following Phaser 2.x: the engine draws the full scene first via `render-scene!` (tilemap layers + entities), then calls the user's `render:` hook. The hook is for post-render overlays only — debug info, HUD elements, custom visuals. It does not replace or suppress the engine's render pass.
-
----
-
-## Physics
-
-Physics (`physics.scm`) is a library, not a pipeline. `game-run!` does not call any physics function automatically. Users who want physics `(require-extension downstroke/physics)` and call functions from their `update:` hook.
-
----
-
-## Public Accessors
-
-All `game-*` readers and `game-*-set!` mutators are generated by `defstruct` and exported. Additional convenience accessors:
-
-| Accessor | Description |
-|---|---|
-| `game-renderer` | SDL2 renderer — available from `preload:` onward |
-| `game-window` | SDL2 window |
-| `game-scene` / `game-scene-set!` | Current scene struct; user sets this in `create:` |
-| `game-camera` | Convenience: `(scene-camera (game-scene game))` — derived, not a struct field. Only valid after `create:` sets a scene; calling before that is an error. |
-| `game-assets` | Full asset registry hash table |
-| `game-input` | Current `input-state` record |
-| `game-input-config` | Current `input-config` record |
-| `(game-asset game key)` | Convenience: `(asset-ref (game-assets game) key)` |
-| `(game-asset-set! game key val)` | Convenience: `(asset-set! (game-assets game) key val)` |
-
-`game-camera` is not a struct field — it is a derived accessor:
-```scheme
-(define (game-camera game)
-  (scene-camera (game-scene game)))
-```
-
----
-
-## Scene-Level Preloading
-
-Out of scope for this milestone. A `preload:` slot will be reserved in the scene struct when `scene-loader.scm` is implemented (Milestone 7), and the two-level asset registry (global + per-scene) will be designed then.
-
----
-
-## macroknight Port
-
-macroknight's `game.scm` must be ported to use `make-game` + `game-run!` as part of this milestone. It is the primary integration test.
-
-**What moves to the engine:** SDL2 init block (lines 87–137), the main loop (line 659+), and all frame-level rendering.
-
-**What stays in macroknight `game.scm`:** Only the three lifecycle hooks and `game-run!`:
-- `preload:` — load fonts, sounds, tilemaps (currently scattered across lines 87–137)
-- `create:` — build initial scene (currently `make-initial-game-state`, line 196)
-- `update:` — game logic, input dispatch, physics calls (currently the per-frame update functions)
-
-**Acceptance criterion:** macroknight compiles (`make` succeeds), the game runs and plays correctly (title screen → stage select → gameplay), and `game.scm` is ≤50 lines with no SDL2 init or frame-loop boilerplate.
-
----
-
-## Out of Scope
-
-- Scene-level preloading (Milestone 7)
-- Asset-type-specific load functions (`game-load-tilemap!`, `game-load-font!`, etc.) — Milestone 6
-- `game-running?` quit flag
-- Scene state machine (Milestone 9)
-- AI tag lookup (Milestone 10)
-- Extraction of `animation`, `ai`, `prefabs`, `mixer`, `sound` modules into downstroke