# Milestone 8 — Game Object and Lifecycle API

> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.

**Goal:** Introduce `make-game` + `game-run!` as the public entry point for downstroke, backed by a minimal asset registry, and port macroknight to use them.

**Architecture:** Two new modules (`assets.scm` — key/value registry; `engine.scm` — game struct, lifecycle, frame loop), plus `render-scene!` added to `renderer.scm`. `game-run!` owns SDL2 init, window/renderer creation, and the frame loop; lifecycle hooks (`preload:`, `create:`, `update:`, `render:`) are user-supplied lambdas.

**Tech Stack:** Chicken Scheme, SDL2 (sdl2 egg), sdl2-ttf, sdl2-image, SRFI-64 (tests), defstruct egg

**Spec:** `docs/superpowers/specs/2026-04-05-milestone-8-game-object-lifecycle-design.md`

---

## File Map

| Action | File | Purpose |
|---|---|---|
| Create | `assets.scm` | Key→value asset registry |
| Create | `tests/assets-test.scm` | SRFI-64 unit tests for assets.scm |
| Modify | `renderer.scm` | Add `render-scene!` |
| Modify | `tests/renderer-test.scm` | Add tests for `render-scene!` |
| Create | `engine.scm` | `make-game`, `game-run!`, accessors |
| Create | `tests/engine-test.scm` | Unit tests for make-game, accessors (SDL2 mocked) |
| Modify | `Makefile` | Add assets + engine to build, add test targets |
| Modify | `/home/gene/src/macroknight/game.scm` | Port to `make-game` + `game-run!` |

---

## Task 1: `assets.scm` — minimal key/value registry

**Files:**
- Create: `assets.scm`
- Create: `tests/assets-test.scm`

### What this module does

A thin wrapper around a hash table. No asset-type logic — that's Milestone 6. Three public functions:

```scheme
(make-asset-registry)          ;; → hash-table
(asset-set! registry key val)  ;; → unspecified (mutates)
(asset-ref registry key)       ;; → value or #f if missing
```

- [ ] **Step 1: Write the failing tests**

Create `tests/assets-test.scm`:

```scheme
(import scheme (chicken base) srfi-64)

(include "assets.scm")
(import downstroke/assets)

(test-begin "assets")

(test-group "make-asset-registry"
  (test-assert "returns a value"
    (make-asset-registry)))

(test-group "asset-set! and asset-ref"
  (let ((reg (make-asset-registry)))
    (test-equal "missing key returns #f"
      #f
      (asset-ref reg 'missing))

    (asset-set! reg 'my-tilemap "data")
    (test-equal "stored value is retrievable"
      "data"
      (asset-ref reg 'my-tilemap))

    (asset-set! reg 'my-tilemap "updated")
    (test-equal "overwrite replaces value"
      "updated"
      (asset-ref reg 'my-tilemap))

    (asset-set! reg 'other 42)
    (test-equal "multiple keys coexist"
      "updated"
      (asset-ref reg 'my-tilemap))
    (test-equal "second key retrievable"
      42
      (asset-ref reg 'other))))

(test-end "assets")
```

- [ ] **Step 2: Run test to confirm it fails**

```bash
cd /home/gene/src/downstroke
csi -s tests/assets-test.scm
```

Expected: error — `assets.scm` not found / `downstroke/assets` not defined.

- [ ] **Step 3: Implement `assets.scm`**

Create `assets.scm`:

```scheme
(module downstroke/assets *

(import scheme
        (chicken base)
        (srfi 69))

(define (make-asset-registry)
  (make-hash-table))

(define (asset-set! registry key value)
  (hash-table-set! registry key value))

(define (asset-ref registry key)
  (hash-table-ref/default registry key #f))

) ;; end module
```

- [ ] **Step 4: Run test to confirm it passes**

```bash
cd /home/gene/src/downstroke
csi -s tests/assets-test.scm
```

Expected: all tests pass, no failures reported.

- [ ] **Step 5: Commit**

```bash
cd /home/gene/src/downstroke
git add assets.scm tests/assets-test.scm
git commit -m "feat: add assets.scm — minimal key/value asset registry"
```

---

## Task 2: Add `render-scene!` to `renderer.scm`

**Files:**
- Modify: `renderer.scm` (add one function after `draw-entities`)
- Modify: `tests/renderer-test.scm` (add one test group)

### What this adds

`render-scene!` draws a complete scene (all tilemap layers + all entities) given a renderer and a scene struct. It delegates to the already-tested `draw-tilemap` and `draw-entities`.

Existing signatures in `renderer.scm`:
- `(draw-tilemap renderer camera tileset-texture tilemap)` — 4 args
- `(draw-entities renderer camera tileset tileset-texture entities)` — 5 args

The `tileset` is extracted from `tilemap` via the `tilemap-tileset` accessor (from `tilemap.scm`).

- [ ] **Step 1: Write the failing test**

Add to `tests/renderer-test.scm`, before `(test-end "renderer")`:

```scheme
(test-group "render-scene!"
  ;; render-scene! calls draw-tilemap and draw-entities — both are mocked to return #f.
  ;; We verify it doesn't crash on a valid scene and returns unspecified.
  (let* ((cam      (make-camera x: 0 y: 0))
         (tileset  (make-tileset tilewidth: 16 tileheight: 16
                                 spacing: 0 tilecount: 100 columns: 10
                                 image-source: "" image: #f))
         (layer    (make-layer name: "ground" width: 2 height: 2
                               map: '((1 2) (3 4))))
         (tilemap  (make-tilemap width: 2 height: 2
                                 tilewidth: 16 tileheight: 16
                                 tileset-source: ""
                                 tileset: tileset
                                 layers: (list layer)
                                 objects: '()))
         (scene    (make-scene entities: '()
                               tilemap: tilemap
                               camera: cam
                               tileset-texture: #f)))
    (test-assert "does not crash on valid scene"
      (begin (render-scene! #f scene) #t))))
```

- [ ] **Step 2: Run test to confirm it fails**

```bash
cd /home/gene/src/downstroke
csi -s tests/renderer-test.scm
```

Expected: error — `render-scene!` not defined.

- [ ] **Step 3: Add `render-scene!` to `renderer.scm`**

Add after the `draw-entities` definition (before the closing `)`):

```scheme
  ;; --- Scene drawing ---

  (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)))
```

- [ ] **Step 4: Run tests to confirm they pass**

```bash
cd /home/gene/src/downstroke
csi -s tests/renderer-test.scm
```

Expected: all tests pass.

- [ ] **Step 5: Commit**

```bash
cd /home/gene/src/downstroke
git add renderer.scm tests/renderer-test.scm
git commit -m "feat: add render-scene! to renderer — draw full scene in one call"
```

---

## Task 3: `engine.scm` — game struct, constructor, accessors

**Files:**
- Create: `engine.scm`
- Create: `tests/engine-test.scm`

This task covers only the data structure and constructor — no `game-run!` yet. TDD applies to the parts we can unit-test (struct creation, accessors).

`game-run!` requires a live SDL2 window and cannot be unit-tested; it is tested in Task 6 via macroknight integration.

### Mock strategy for tests

`engine.scm` imports `renderer.scm`, `input.scm`, `world.scm`, `assets.scm`, and the SDL2 sub-libraries. The test file follows the same mock-module pattern as `tests/renderer-test.scm`: define mock modules that satisfy the imports, then `(include "engine.scm")`.

- [ ] **Step 1: Write the failing tests**

Create `tests/engine-test.scm`:

```scheme
(import scheme (chicken base) (chicken keyword) srfi-64 defstruct)

;; --- Mocks ---

(module sdl2 *
  (import scheme (chicken base))
  (define (set-main-ready!) #f)
  (define (init! . args) #f)
  (define (quit! . args) #f)
  (define (get-ticks) 0)
  (define (delay! ms) #f)
  (define (pump-events!) #f)
  (define (has-events?) #f)
  (define (make-event) #f)
  (define (poll-event! e) #f)
  (define (num-joysticks) 0)
  (define (is-game-controller? i) #f)
  (define (game-controller-open! i) #f)
  (define (create-window! . args) 'mock-window)
  (define (create-renderer! . args) 'mock-renderer)
  (define (destroy-window! . args) #f)
  (define (render-clear! . args) #f)
  (define (render-present! . args) #f))
(import (prefix sdl2 "sdl2:"))

(module sdl2-ttf *
  (import scheme (chicken base))
  (define (init!) #f))
(import (prefix sdl2-ttf "ttf:"))

(module sdl2-image *
  (import scheme (chicken base))
  (define (init! . args) #f))
(import (prefix sdl2-image "img:"))

;; --- Real deps (include order follows dependency order) ---
(import simple-logger)   ;; required by input.scm
(include "entity.scm")   (import downstroke/entity)
(include "tilemap.scm")  (import downstroke/tilemap)
(include "world.scm")    (import downstroke/world)
(include "input.scm")    (import downstroke/input)
(include "assets.scm")   (import downstroke/assets)

;; Mock renderer (render-scene! can't run without real SDL2)
(module downstroke/renderer *
  (import scheme (chicken base))
  (define (render-scene! . args) #f))
(import downstroke/renderer)

(include "engine.scm")
(import downstroke/engine)

;; --- Tests ---

(test-begin "engine")

(test-group "make-game defaults"
  (let ((g (make-game)))
    (test-equal "default title"
      "Downstroke Game"
      (game-title g))
    (test-equal "default width"
      640
      (game-width g))
    (test-equal "default height"
      480
      (game-height g))
    (test-equal "default frame-delay"
      16
      (game-frame-delay g))
    (test-equal "scene starts as #f"
      #f
      (game-scene g))
    (test-equal "window starts as #f"
      #f
      (game-window g))
    (test-equal "renderer starts as #f"
      #f
      (game-renderer g))
    (test-assert "assets registry is created"
      (game-assets g))
    (test-assert "input state is created"
      (game-input g))))

(test-group "make-game with keyword args"
  (let ((g (make-game title: "My Game" width: 320 height: 240 frame-delay: 33)))
    (test-equal "custom title" "My Game" (game-title g))
    (test-equal "custom width" 320 (game-width g))
    (test-equal "custom height" 240 (game-height g))
    (test-equal "custom frame-delay" 33 (game-frame-delay g))))

(test-group "game-asset and game-asset-set!"
  (let ((g (make-game)))
    (test-equal "missing key returns #f"
      #f
      (game-asset g 'no-such-asset))
    (game-asset-set! g 'my-font 'font-object)
    (test-equal "stored asset is retrievable"
      'font-object
      (game-asset g 'my-font))
    (game-asset-set! g 'my-font 'updated-font)
    (test-equal "overwrite replaces asset"
      'updated-font
      (game-asset g 'my-font))))

(test-group "make-game hooks default to #f"
  (let ((g (make-game)))
    (test-equal "preload-hook is #f" #f (game-preload-hook g))
    (test-equal "create-hook is #f"  #f (game-create-hook g))
    (test-equal "update-hook is #f"  #f (game-update-hook g))
    (test-equal "render-hook is #f"  #f (game-render-hook g))))

(test-group "make-game accepts hook lambdas"
  (let* ((called #f)
         (g (make-game update: (lambda (game dt) (set! called #t)))))
    (test-assert "update hook is stored"
      (procedure? (game-update-hook g)))))

(test-end "engine")
```

- [ ] **Step 2: Run test to confirm it fails**

```bash
cd /home/gene/src/downstroke
csi -s tests/engine-test.scm
```

Expected: error — `engine.scm` not found.

- [ ] **Step 3: Implement `engine.scm` struct + constructor + accessors (no `game-run!`)**

Create `engine.scm`. `game-run!` is a stub for now — it will be filled in Task 4.

```scheme
(module downstroke/engine *

(import scheme
        (chicken base)
        (chicken keyword)
        (prefix sdl2 "sdl2:")
        (prefix sdl2-ttf "ttf:")
        (prefix sdl2-image "img:")
        defstruct
        downstroke/world
        downstroke/input
        downstroke/assets
        downstroke/renderer)

;; ── Game struct ────────────────────────────────────────────────────────────
;; constructor: make-game* (raw) so we can define make-game as keyword wrapper

(defstruct (game constructor: make-game*)
  title width height
  window renderer
  input          ;; input-state record
  input-config   ;; input-config record
  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; #f until create: runs

;; ── Public constructor ─────────────────────────────────────────────────────

(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)
    input-config: input-config
    assets:       (make-asset-registry)
    frame-delay:  frame-delay
    preload-hook: preload
    create-hook:  create
    update-hook:  update
    render-hook:  render))

;; ── Convenience accessors ──────────────────────────────────────────────────

;; game-camera: derived from the current scene (only valid after create: runs)
(define (game-camera game)
  (scene-camera (game-scene game)))

;; game-asset: retrieve an asset by key
(define (game-asset game key)
  (asset-ref (game-assets game) key))

;; game-asset-set!: store an asset by key
(define (game-asset-set! game key value)
  (asset-set! (game-assets game) key value))

;; ── game-run! ──────────────────────────────────────────────────────────────
;; Stub — implemented in Task 4

(define (game-run! game)
  (error "game-run! not yet implemented"))

) ;; end module
```

- [ ] **Step 4: Run tests to confirm they pass**

```bash
cd /home/gene/src/downstroke
csi -s tests/engine-test.scm
```

Expected: all tests pass.

- [ ] **Step 5: Commit**

```bash
cd /home/gene/src/downstroke
git add engine.scm tests/engine-test.scm
git commit -m "feat: add engine.scm — game struct, make-game constructor, accessors"
```

---

## Task 4: Implement `game-run!`

**Files:**
- Modify: `engine.scm` (replace stub with real implementation)

`game-run!` is tested via macroknight integration in Task 6, not via unit tests (it requires a real SDL2 display).

- [ ] **Step 1: Replace the `game-run!` stub in `engine.scm`**

Replace the stub `(define (game-run! game) (error ...))` with:

```scheme
(define (game-run! game)
  ;; 1. SDL2 init (audio excluded — mixer.scm not yet extracted;
  ;;    user calls init-audio! in their preload: hook)
  (sdl2:set-main-ready!)
  (sdl2:init! '(video joystick game-controller))
  (ttf:init!)
  (img:init! '(png))

  ;; Open any already-connected game controllers
  (let init-controllers ((i 0))
    (when (< i (sdl2:num-joysticks))
      (when (sdl2:is-game-controller? i)
        (sdl2:game-controller-open! i))
      (init-controllers (+ i 1))))

  ;; 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 — user loads assets here
  (when (game-preload-hook game)
    ((game-preload-hook game) game))

  ;; 4. create: hook — user builds initial scene here
  (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)))
      ;; Collect all pending SDL2 events
      (sdl2:pump-events!)
      (let* ((events (let collect ((lst '()))
                       (if (not (sdl2:has-events?))
                           (reverse lst)
                           (let ((e (sdl2:make-event)))
                             (sdl2:poll-event! e)
                             (collect (cons e lst))))))
             (input  (input-state-update (game-input game) events
                                         (game-input-config game))))
        (game-input-set! game input)
        (unless (input-held? input 'quit)
          ;; update: hook — user game logic
          (when (game-update-hook game)
            ((game-update-hook game) game dt))
          ;; render: engine draws world, then user overlay
          (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!))
```

Note: `sdl2:pump-events!` processes the OS event queue; `sdl2:has-events?`/`sdl2:make-event`/`sdl2:poll-event!` drain it into a list. This matches the pattern used in macroknight's existing game loop (lines 661–667).

**Spec discrepancy:** The spec document shows `(sdl2:collect-events!)` in its pseudocode — that function does not exist in the sdl2 egg. The plan's pump+collect loop above is the correct implementation. Ignore the spec's `sdl2:collect-events!` reference.

- [ ] **Step 2: Verify engine-test.scm still passes**

```bash
cd /home/gene/src/downstroke
csi -s tests/engine-test.scm
```

Expected: all tests pass (game-run! itself is not called in unit tests).

- [ ] **Step 3: Commit**

```bash
cd /home/gene/src/downstroke
git add engine.scm tests/engine-test.scm
git commit -m "feat: implement game-run! — SDL2 init, lifecycle hooks, frame loop"
```

---

## Task 5: Update the Makefile

**Files:**
- Modify: `Makefile`

- [ ] **Step 1: Add `assets` and `engine` to `MODULE_NAMES`**

In `Makefile`, change:
```makefile
MODULE_NAMES := entity tilemap world input physics renderer
```
to:
```makefile
MODULE_NAMES := entity tilemap world input physics renderer assets engine
```

- [ ] **Step 2: Add dependency declarations**

Add after `bin/renderer.o: bin/entity.o bin/tilemap.o bin/world.o`:

```makefile
bin/assets.o:
bin/engine.o: bin/renderer.o bin/world.o bin/input.o bin/assets.o
```

`assets.scm` has no inter-module dependencies. `engine.scm` depends on renderer, world, input, and assets.

- [ ] **Step 3: Add test targets**

In the `test:` rule, add:
```makefile
	@csi -s tests/assets-test.scm
	@csi -s tests/engine-test.scm
```

- [ ] **Step 4: Verify the build**

```bash
cd /home/gene/src/downstroke
make clean && make
```

Expected: all `.o` files created in `bin/`, including `bin/assets.o` and `bin/engine.o`. No errors.

- [ ] **Step 5: Run all tests**

```bash
cd /home/gene/src/downstroke
make test
```

Expected: all test suites pass.

- [ ] **Step 6: Commit**

```bash
cd /home/gene/src/downstroke
git add Makefile
git commit -m "build: add assets and engine modules to Makefile"
```

---

## Task 6: Port macroknight to `make-game` + `game-run!`

**Files:**
- Modify: `/home/gene/src/macroknight/game.scm`

This is the integration test for the whole milestone. macroknight's current `game.scm` is ~678 lines with SDL2 init, the frame loop, and all game state mixed together. After this task it should be ≤50 lines: only `make-game`, the three lifecycle hooks, and `game-run!`.

### What moves vs. what stays

**Moves to engine (delete from game.scm):**
- Lines 87–137: SDL2 init block — from `(sdl2:set-main-ready!)` through `(define *title-font* ...)` inclusive. This covers: `sdl2:set-main-ready!`, `sdl2:init!`, `init-game-controllers!` call, `ttf:init!`, `img:init!`, audio init calls, `on-exit` handlers, exception handler wrapper, `sdl2:set-hint!`, `sdl2:create-window!`, `sdl2:create-renderer!`, `ttf:open-font` calls.
- Lines 659–673: The main `let/cc` game loop

**Stays in macroknight (wrapped in lifecycle hooks):**
- `init-audio!` + `load-sounds!` + `load-music!` → `preload:` hook
- `ttf:open-font` calls (fonts) → `preload:` hook
- `make-initial-game-state` → `create:` hook
- `update-game-state` dispatch → `update:` hook
- `render-frame` mode dispatch (minus clear/present) → `render:` hook

**macroknight-specific state** (`game-state` struct: mode, menu-cursor, scene, input, etc.) stays as the module-level `*gs*` variable — set in `create:`, mutated in `update:`.

**`render-frame` split:** The existing `render-frame` calls `sdl2:render-clear!` and `sdl2:render-present!` — those are now owned by the engine. Modify `render-frame` to remove those two calls, keeping only the draw-color set and the mode dispatch. The modified `render-frame` becomes the body of the `render:` hook. Since the background color is black (`0 0 0`) and the engine's clear already clears to black, there is no visual difference.

### Implementation steps

- [ ] **Step 1: Add `downstroke/engine` to macroknight's imports**

In `/home/gene/src/macroknight/game.scm`, add to the import list:
```scheme
downstroke/engine
downstroke/assets
```

- [ ] **Step 2: Restructure as `make-game` call**

Replace the top-level SDL2 init block and the game loop at the bottom of `game.scm` with a `make-game` call. The three lifecycle hooks capture the existing functions from the rest of the file.

**First, modify `render-frame`** to remove the SDL2 clear/present calls (the engine now owns those). Change lines 378–385 of `game.scm` from:

```scheme
(define (render-frame gs)
  (set! (sdl2:render-draw-color *renderer*) +background-color+)
  (sdl2:render-clear! *renderer*)
  (case (game-state-mode gs)
    ((main-menu)    (draw-main-menu    gs))
    ((stage-select) (draw-stage-select gs))
    ((playing)      (draw-playing      gs)))
  (sdl2:render-present! *renderer*))
```

to:

```scheme
(define (render-frame gs)
  (set! (sdl2:render-draw-color *renderer*) +background-color+)
  (case (game-state-mode gs)
    ((main-menu)    (draw-main-menu    gs))
    ((stage-select) (draw-stage-select gs))
    ((playing)      (draw-playing      gs))))
```

**Then add module-level state and the engine entry point** at the bottom of `game.scm` (replacing the old `let/cc` loop):

```scheme
;; ── Module-level game state ────────────────────────────────────────────────

(define *gs* #f)  ;; macroknight game state, set in create:

;; ── Engine entry point ─────────────────────────────────────────────────────

(define *the-game*
  (make-game
    title:       "MacroKnight"
    width:       +screen-width+
    height:      +screen-height+
    frame-delay: 10

    preload: (lambda (game)
               ;; Audio (mixer not yet extracted — call directly)
               (init-audio!)
               (load-sounds! '((jump . "assets/jump.wav")))
               (load-music!  "assets/theme.ogg")
               (play-music!  0.6)
               ;; Fonts
               (set! *font*       (ttf:open-font "assets/DejaVuSans.ttf" 12))
               (set! *title-font* (ttf:open-font "assets/DejaVuSans.ttf" 32))
               ;; Make the SDL2 renderer available to macroknight functions
               (set! *renderer* (game-renderer game)))

    create: (lambda (game)
              (set! *gs* (make-initial-game-state)))

    update: (lambda (game dt)
              ;; update-game-state uses a continuation for the "quit" menu item;
              ;; pass a no-op since the engine handles Escape→quit automatically.
              (update-game-state *gs* (lambda () #f))
              (maybe-advance-level *gs*))

    render: (lambda (game)
              ;; engine has already called render-clear! and render-scene!
              ;; (game-scene is #f so render-scene! is a no-op for now);
              ;; render-frame draws the mode-specific content.
              (render-frame *gs*))))

(game-run! *the-game*)
```

**Notes:**
- `*renderer*`, `*font*`, `*title-font*` remain module-level variables (set in `preload:`). Keep their `(define ...)` declarations at the top of `game.scm` as `(define *font* #f)` etc. (uninitialized — they'll be set in `preload:`).
- The engine's input handles Escape → quit via `input-held? input 'quit`; the old `let/cc exit-main-loop!` mechanism and `exit-main-loop!` call in `update-game-state` are no longer needed. **However, do not change `update-game-state` in this milestone** — the `(lambda () #f)` passed as `exit!` means the "Quit" menu item is a no-op for now. Fix it in a later milestone.
- `(game-scene game)` is never set from macroknight, so the engine's `render-scene!` is always a no-op. All rendering happens in the `render:` hook via `render-frame`. This is intentional for this port milestone.

- [ ] **Step 3: Remove the old SDL2 init block from `game.scm`**

Delete lines 87–137 — everything from `(sdl2:set-main-ready!)` through `(define *title-font* (ttf:open-font ...))` inclusive.

This also removes the `on-exit` cleanup handlers (lines 107–108) and the custom exception handler (lines 113–117). **This is intentional for this milestone.** The engine's `game-run!` calls `sdl2:destroy-window!` and `sdl2:quit!` at cleanup, but does not install an exception handler. If macroknight crashes mid-run, SDL2 will not be shut down cleanly. This will be addressed in a later milestone (either by adding error handling to `game-run!` or by macroknight wrapping `game-run!` in a guard).

After deletion, add these uninitialized stubs near the top of `game.scm` (after the imports) so the rest of the file can still reference the variables. Note: `*window*` only appears inside the deleted range, so its stub is precautionary only.

```scheme
(define *window*     #f)  ;; owned by engine; not used after this port
(define *renderer*   #f)  ;; set in preload:
(define *font*       #f)  ;; set in preload:
(define *title-font* #f)  ;; set in preload:
(define *text-color* (sdl2:make-color 255 255 255))
```

- [ ] **Step 4: Remove the old main loop from `game.scm`**

Delete lines 659–678 (the `let/cc` game loop through the end of the file including the `"Bye!\n"` print). The engine's `game-run!` replaces it. The new `(define *the-game* ...)` and `(game-run! *the-game*)` from Step 2 are the new end of the file.

- [ ] **Step 5: Build macroknight to verify it compiles**

```bash
cd /home/gene/src/macroknight
make clean && make
```

Expected: successful compilation. Fix any symbol-not-found or import errors before continuing.

- [ ] **Step 6: Run macroknight to verify it plays**

```bash
cd /home/gene/src/macroknight
./bin/game
```

Expected: game launches, title screen appears, gameplay works correctly (title → stage select → play a level). Press Escape to quit.

**Known regression (intentional):** Selecting "Quit" from the main menu is a no-op in this milestone. The old `exit-main-loop!` continuation no longer exists; the `update:` hook passes `(lambda () #f)` in its place. This will be fixed in a later milestone.

- [ ] **Step 7: Verify game.scm is ≤50 lines**

```bash
wc -l /home/gene/src/macroknight/game.scm
```

If still over 50 lines, extract helper functions that belong in other modules. Game-specific logic (menu rendering, level loading) can stay; SDL2 boilerplate must be gone.

- [ ] **Step 8: Commit**

```bash
cd /home/gene/src/macroknight
git add game.scm
git commit -m "feat: port macroknight to use make-game + game-run! (Milestone 8)"
```

Then commit the downstroke side:

```bash
cd /home/gene/src/downstroke
git add -A
git commit -m "feat: Milestone 8 complete — make-game + game-run! engine entry point"
```

---

## Acceptance Criteria

- [ ] `make test` in downstroke passes all suites including assets and engine
- [ ] `make` in downstroke builds all modules including `bin/assets.o` and `bin/engine.o`
- [ ] `make && ./bin/game` in macroknight launches and plays correctly
- [ ] macroknight `game.scm` is ≤50 lines with no SDL2 init or frame-loop boilerplate
- [ ] `make-game` + `game-run!` are the sole entry point — no top-level SDL2 calls outside them