Expand voxel gameplay, lighting, full-height streaming and world imports

Add shared Rust/WASM physics, worker meshing and diagnostics, 64-chunk full-height streaming, atlas texture support, and baseline world import. Document the current implementation and include the supplied in-game lobby screenshot.

README.md

@@ -8,6 +8,12 @@ An independent, open-source voxel engine written in Rust. The local MVP includes
 
 Minecraft is mentioned to identify compatibility targets and data sources. Minecraft names, brands, and assets remain the property of their respective owners. See the [Minecraft Usage Guidelines](https://www.minecraft.net/en-us/usage-guidelines).
 
+## In-game demonstration
+
+![An imported minigames lobby at night, with block lighting and another player visible in the Shacraft browser client](docs/images/minigames-lobby-night.png)
+
+An imported minigames lobby running in Shacraft, with multiplayer avatars and block lighting. This development screenshot uses original Minecraft textures for a local compatibility test; the world and texture pack are not bundled with the repository. Render distance supports up to 64 chunks (1,024 blocks), with progressive loading across the full world height, Y=−64 through 319.
+
 ## Quick start
 
 You need Rust 1.96+, a C compiler for bundled SQLite, and a browser with WebGL2. Java and Node.js are not required to play. The first run downloads Cargo dependencies and builds the release binaries; subsequent runs use the existing binaries.
@@ -18,9 +24,10 @@ cd shacraft-core
 bash scripts/run.sh --data data --listen 127.0.0.1:4000
 ```
 
-Open **http://127.0.0.1:4000**. The server creates a lobby, a block gallery, and two Spleef arenas automatically. The MVP client currently uses Russian interface text.
+Open **http://127.0.0.1:4000**. The server creates a lobby, a block gallery, two Spleef arenas and a procedural Overworld automatically. Open `http://localhost:4000/?world=overworld` for the large world. The MVP client currently uses Russian interface text.
 
 - **WASD** to move, **Space** to jump, and the mouse to look around. Drag to look if pointer lock is unavailable.
+- **Ctrl** to sprint, **Shift** to crouch, **double-Space / F** to toggle permitted creative flight; Space/Shift ascend/descend.
 - **Left/right click** to remove/place a block; **E** for the material library, **T** for chat, and **F3** for diagnostics.
 - Select a world in the upper-left corner. To play Spleef, two players join the same arena and start a match from the menu.
 
@@ -29,7 +36,8 @@ World data is stored under `--data`. Stop the server with Ctrl+C. Acknowledged b
 ## What's included
 
 - **`shacraft-core`** — compact 16³ sections, a bounded shared cache, SQLite with WAL and FULL synchronization, immutable snapshots, independent world edits, revisions, idempotent operations, undo, and reset. No graphics or networking dependencies.
-- **`shacraft-server`** — authoritative movement, collision shapes and interactions, WebSocket/HTTP, persistent entities and settings, and a complete Spleef match cycle.
+- **`shacraft-server`** — authoritative movement, collision shapes and interactions, WebSocket/HTTP, persistent entities and settings, and a complete Spleef match cycle. The seeded Overworld spans 384 vertical layers and nearly ±30 million horizontal blocks, with bounded CPU generation and section streaming.
+- **`shacraft-physics`** — shared 20 Hz Rust/WASM player movement, client prediction and reconciliation, tested against measured Java 26.2 movement kernels, collision cases and block callbacks. See [physics and its limits](docs/PHYSICS.md).
 - **`client/`** — a custom renderer, material library, players and entities, chat, world switching, reconnection, and verified package downloads.
 - **`shacraft-mcp`** — a separate stdio MCP server with 17 tools, resources, and a prompt; build plans, reads, undo, entities, arenas, metrics, and PNG previews.
 - **`shacraft-content`** — **1,196 blocks, 32,366 states, and 158 entity types from Java 26.2**, DataVersion 4903. Source identifiers, measured collision shapes, and independently authored rendering templates. An additional trampoline block demonstrates extensions.
@@ -38,9 +46,9 @@ World data is stored under `--data`. Stop the server with Ctrl+C. Acknowledged b
 
 ## Compatibility and scope
 
-This MVP does not implement full vanilla AI, redstone, inventories, or fluid simulation. Context-dependent shapes are marked separately. After edits, the converter uses an explicit `best-effort` mode; an unchanged original can be returned byte for byte. Full Minecraft gameplay or NeoForge mod compatibility is not claimed. Minecraft source code, binaries, and original visual/audio assets are not distributed.
+This MVP does not implement full vanilla AI, redstone, inventories, or fluid simulation. Context-dependent shapes are marked separately. After edits, the converter uses an explicit `best-effort` mode; an unchanged original can be returned byte for byte. Full Minecraft gameplay or NeoForge mod compatibility is not claimed. Minecraft source code, binaries, texture packs, and audio files are not bundled.
 
-The release benchmark measured a maximum of **59.65 MiB RSS/VmHWM with 10 moving clients** and **50.50 MiB RSS with 100 idle world forks**. These are results from a short local workload, not a comparison with Paper or a production capacity guarantee. See [verification and limits](docs/VERIFICATION.md).
+The earlier MVP release benchmark measured a maximum of **59.65 MiB RSS/VmHWM with 10 moving clients** and **50.50 MiB RSS with 100 idle world forks**. These measurements predate the shared movement solver and are results from a short local workload, not a comparison with Paper or a production capacity guarantee. See [verification and limits](docs/VERIFICATION.md).
 
 ## MCP and world conversion
 
@@ -61,13 +69,14 @@ The Control API token is created at `data/control.token` with mode 0600 on Unix
 
 ```bash
 # Rust checks, crash recovery, JavaScript tests, and real HTTP/WebSocket clients:
+rustup target add wasm32-unknown-unknown
 bash scripts/verify.sh
 # Release benchmark with budgets set before the run:
 cargo build --release --workspace --locked
 node scripts/benchmark_server.mjs --output artifacts/server-benchmark.json
 ```
 
-Node.js 22+ is required for network and JavaScript checks; Python 3 is required for the storage crash test. The independent MCP SDK and Java/NBT verification procedures are documented in [VERIFICATION](docs/VERIFICATION.md). Recorded checks include 84 Rust tests, 6 JavaScript tests, and 14 HTTP/WebSocket scenario groups.
+Node.js 22+ is required for network and JavaScript checks; Python 3 is required for the storage crash test. Verification rebuilds the physics WebAssembly with the Rust `wasm32-unknown-unknown` target; playing uses the included artifact. The independent MCP SDK and Java/NBT verification procedures are documented in [VERIFICATION](docs/VERIFICATION.md).
 
 ## Documentation
 
@@ -75,6 +84,8 @@ Node.js 22+ is required for network and JavaScript checks; Python 3 is required
 - [Requirements](docs/REQUIREMENTS.md), [implementation plan](docs/PLAN.md), and [design decisions](docs/DECISIONS.md)
 - [Core contracts](docs/CONTRACT.md), [memory and storage](docs/MEMORY_AND_STORAGE.md), and [development tools](docs/DEVELOPMENT.md)
 - [Server](docs/SERVER.md), [client](docs/CLIENT.md), and [MCP](docs/MCP.md)
+- [Player physics, reference measurements and prediction](docs/PHYSICS.md)
+- [Procedural worlds, streaming and movement diagnostics](docs/WORLD_STREAMING.md)
 - [Content catalog](docs/CONTENT.md), [compatibility](docs/COMPATIBILITY.md), [world interchange](docs/interop.md), and [packages](docs/PACKAGES.md)
 - [Acceptance criteria](docs/ACCEPTANCE.md) and [verification evidence](docs/VERIFICATION.md)