diff --git a/mrpci-core/src/bin/mrpci-headless/main.rs b/mrpci-core/src/bin/mrpci-headless/main.rs
index bf2852a..673cba1 100644
--- a/mrpci-core/src/bin/mrpci-headless/main.rs
+++ b/mrpci-core/src/bin/mrpci-headless/main.rs
@@ -30,7 +30,9 @@ fn main() {
                --sample            write the demo game into games/neon-precinct\n\
                --seed N            seed the deterministic RNG\n\
                --room N            jump to room N at boot (with --render-room etc)\n\
-               --ticks N           advance N cycles at boot (palette cycling, NPCs)\n"
+               --ticks N           advance N cycles at boot (palette cycling, NPCs)\n\
+               --bundle FILE       boot from a single-JSON world bundle (the wasm path)\n\
+               --export-bundle F   write the loaded game as one bundle JSON and exit\n"
         );
         return;
     }
@@ -48,8 +50,39 @@ fn main() {
     }
 
     let game_dir = get("--game").unwrap_or_else(|| ".".into());
-    let world = World::load_game(&game_dir);
+    // `--bundle FILE` boots from a single-JSON world instead of a folder —
+    // the exact path a filesystem-less (wasm) build takes, testable here.
+    let world = match get("--bundle") {
+        Some(path) => {
+            let s = std::fs::read_to_string(&path).unwrap_or_else(|e| {
+                eprintln!("can't read bundle {}: {}", path, e);
+                std::process::exit(1);
+            });
+            let bundle: mrpci_core::WorldBundle = serde_json::from_str(&s).unwrap_or_else(|e| {
+                eprintln!("bad bundle {}: {}", path, e);
+                std::process::exit(1);
+            });
+            let mut sprites: Vec<_> = bundle.sprites.clone().into_iter().collect();
+            sprites.sort_by(|a, b| a.0.cmp(&b.0));
+            World::from_memory(
+                bundle.manifest,
+                bundle.rooms,
+                bundle.scripts,
+                sprites,
+            )
+        }
+        None => World::load_game(&game_dir),
+    };
     let mut gs = GameState::new(world);
+
+    if let Some(path) = get("--export-bundle") {
+        let bundle = gs.world.to_bundle();
+        let j = serde_json::to_string(&bundle).expect("bundle serializes");
+        std::fs::write(&path, &j).expect("write bundle");
+        println!("bundle exported: {} ({} rooms, {} scripts, {} sprites, {} bytes)",
+            path, bundle.rooms.len(), bundle.scripts.len(), bundle.sprites.len(), j.len());
+        return;
+    }
     if let Some(seed) = get("--seed").and_then(|s| s.parse::<u64>().ok()) {
         gs.apply(Command::SetSeed { seed });
     }
diff --git a/mrpci-core/src/room.rs b/mrpci-core/src/room.rs
index 53d6214..1c5bfe7 100644
--- a/mrpci-core/src/room.rs
+++ b/mrpci-core/src/room.rs
@@ -280,6 +280,11 @@ pub struct WorldBundle {
     /// Script sources by file name (bundles travel with their logic).
     #[serde(default)]
     pub scripts: HashMap<String, String>,
+    /// Sprite art by name (raw RGBA; quantized per room at bake time).
+    /// Optional so old bundles still load — an empty map keeps whatever
+    /// sprites the receiving World already has.
+    #[serde(default)]
+    pub sprites: HashMap<String, SpriteSrc>,
 }
 
 /// The loaded game: manifest + sprites + the current room baked into the
@@ -485,15 +490,22 @@ impl World {
                 }
             }
         }
-        WorldBundle { manifest: self.manifest.clone(), rooms, scripts }
+        let sprites = self.sprites.iter().map(|(n, s)| (n.clone(), s.clone())).collect();
+        WorldBundle { manifest: self.manifest.clone(), rooms, scripts, sprites }
     }
 
-    /// Replace the loaded world with a bundle (sprites are kept — bundles
-    /// carry world data, not art).
+    /// Replace the loaded world with a bundle. A bundle that carries
+    /// sprites replaces the art wholesale (the wasm/bootstrap path); one
+    /// that doesn't keeps whatever this World already loaded.
     pub fn apply_bundle(&mut self, b: WorldBundle) {
         self.manifest = b.manifest;
         self.overlay = b.rooms.into_iter().collect();
         self.script_overlay = b.scripts.into_iter().collect();
+        if !b.sprites.is_empty() {
+            let mut sprites: Vec<(String, SpriteSrc)> = b.sprites.into_iter().collect();
+            sprites.sort_by(|a, b| a.0.cmp(&b.0));
+            self.sprites = sprites;
+        }
         let start = self.manifest.start_room;
         self.goto_room(start);
     }
diff --git a/mrpci-core/src/view.rs b/mrpci-core/src/view.rs
index 991086a..3e4cb25 100644
--- a/mrpci-core/src/view.rs
+++ b/mrpci-core/src/view.rs
@@ -19,8 +19,10 @@
 use serde::{Deserialize, Serialize};
 
 /// A raw RGBA sprite as loaded from disk — cooked into [`Cel`]s per room so
-/// quantization always matches the room's actual palette.
-#[derive(Clone)]
+/// quantization always matches the room's actual palette. Serde so bundles
+/// can carry art: a filesystem-less build (wasm, tests) gets sprites the
+/// same way it gets rooms — inside one JSON document.
+#[derive(Clone, Serialize, Deserialize)]
 pub struct SpriteSrc {
     pub w: usize,
     pub h: usize,
diff --git a/mrpci-core/tests/bundle.rs b/mrpci-core/tests/bundle.rs
new file mode 100644
index 0000000..df02302
--- /dev/null
+++ b/mrpci-core/tests/bundle.rs
@@ -0,0 +1,44 @@
+//! Bundle round-trip: a game folder → one JSON document → a fully working
+//! World with NO filesystem. This is exactly how a wasm build boots, so it
+//! gets a native test.
+
+use mrpci_core::{Command, GameState, World, WorldBundle};
+
+fn game_dir() -> Option<String> {
+    for p in ["games/neon-precinct", "../games/neon-precinct"] {
+        if std::path::Path::new(p).join("game.json").exists() {
+            return Some(p.to_string());
+        }
+    }
+    None
+}
+
+#[test]
+fn bundle_round_trip_boots_without_fs() {
+    let Some(dir) = game_dir() else {
+        eprintln!("demo game not generated; skipping");
+        return;
+    };
+    let world = World::load_game(dir);
+    let json = serde_json::to_string(&world.to_bundle()).expect("bundle serializes");
+    let bundle: WorldBundle = serde_json::from_str(&json).expect("bundle parses");
+    assert_eq!(bundle.rooms.len(), 3, "all three demo rooms travel");
+    assert!(bundle.scripts.len() >= 4, "main.rhai + room scripts travel");
+    assert!(bundle.sprites.contains_key("keycard"), "art travels");
+
+    let mut sprites: Vec<_> = bundle.sprites.clone().into_iter().collect();
+    sprites.sort_by(|a, b| a.0.cmp(&b.0));
+    let world2 = World::from_memory(bundle.manifest, bundle.rooms, bundle.scripts, sprites);
+    let mut gs = GameState::new(world2);
+    gs.apply(Command::NewGame { room: None });
+
+    // The world is really alive: art cooked, scripts compiled, sim ticking.
+    assert!(gs.world.cel("keycard").is_some(), "sprites quantized from bundle art");
+    let snap = gs.snapshot();
+    assert_eq!(snap.room_name, "Neon Row");
+    assert!(!snap.props.is_empty());
+    gs.apply(Command::Tick { n: 60 });
+    let frame = gs.render_indices(true);
+    assert_eq!(frame.len(), 320 * 190);
+    assert!(frame.iter().any(|&p| p != 0), "frame isn't blank");
+}