Add README and MIT LICENSE

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: Zanges

LICENSE

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+MIT License
+
+Copyright (c) 2026 Zanges
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# Early Input Guard
+
+A small client-side NeoForge mod that stops a class of startup crash in large modpacks: a mouse
+click or key press (or an automatic per-tick event) being dispatched to another mod's input/tick
+listener **before that mod has registered its keybinds** — so the listener dereferences a `null`
+`KeyMapping` and the game hard-crashes.
+
+- **Minecraft:** 1.21.1
+- **Loader:** NeoForge (21.1.x)
+- **Side:** client only
+
+## The problem
+
+In heavily-modded packs the client renders frames and polls input while the loading screen is still
+up, and FML may finish loading in a degraded state. Two things can leave a mod's keybind fields
+`null` when its listeners run:
+
+1. **During the loading screen** — input is polled before every mod's `RegisterKeyMappingsEvent`
+   handler has run.
+2. **In a broken mod state** — if any mod fails to construct, FML "cowardly refuses" to fire the
+   client registration events (including `RegisterKeyMappingsEvent`) for the rest of the session, so
+   keybinds are *never* assigned, yet NeoForge keeps dispatching input and per-tick events.
+
+A single click in either situation reaches a listener like Quark's `HotbarChangerModule` or Arknights
+Endfield's `KeyInputHandler` and crashes with:
+
+```
+java.lang.NullPointerException: Cannot invoke "net.minecraft.client.KeyMapping.isDown()"
+because "...changeHotbarKey" is null
+```
+
+## What it does
+
+It mixes into NeoForge's `ClientHooks` and short-circuits the relevant dispatch hooks while it is
+unsafe to deliver events to mod listeners:
+
+| Hook | Guarded |
+| --- | --- |
+| `onMouseButtonPre` / `onMouseButtonPost` | mouse clicks |
+| `onMouseScroll` | scroll |
+| `onKeyInput` | key presses |
+| `fireClientTickPre` / `fireClientTickPost` | per-tick mod events |
+
+**Suppression conditions:**
+
+- **Input** is dropped when mod loading has errored (`ModLoader.hasErrors()`) **or** a `LoadingOverlay`
+  is active.
+- **Ticks** are dropped when mod loading has errored. Suppressing ticks during a *healthy* loading
+  screen is opt-in via config (see below), since some mods legitimately tick during loading.
+
+This does **not** hide problems: NeoForge's loading-error screen still renders and its buttons still
+work (they dispatch through `Screen.mouseClicked`, a different path), so you can read the errors and
+quit cleanly instead of being thrown into a crash report. It also has no effect on a healthy,
+fully-loaded game — by then nothing is suppressed.
+
+## Config
+
+`config/earlyinputguard-client.toml`:
+
+| Option | Default | Effect |
+| --- | --- | --- |
+| `suppress_ticks_during_loading_screen` | `false` | Also suppress client tick dispatch while a loading screen is active, not just in a broken mod state. |
+
+## Building
+
+Requires JDK 21.
+
+```bash
+./gradlew build
+```
+
+The mod jar is written to `build/libs/`.
+
+## License
+
+MIT