One JAR with Automatic Per-World Matcha Detection — Minecraft 26.2 / 26.3 | Companion 1.4.0

• Replaced four compatibility downloads with one Fabric JAR. Minecraft selects the appropriate internal runtime and bundled JEI version automatically.
• Selects Matcha 1.03, 1.12 or 1.12.5 on Minecraft 26.2, and Matcha 1.12.7-beta on Minecraft 26.3.
• An enabled Matcha world datapack takes priority over an installed Matcha mod. Datapack ZIPs and folders are identified from their metadata, so renaming the file does not affect detection.
• Rechecks when joining/leaving worlds and while a world is open. Catalogues, required assets and optional visual layers switch together; the previous world's selection is cleared on disconnect.
• Supports the official mr_matcha_flavoured mod, including its resource-and-datapack JAR. Its fixed client resource pack is replaced by the Companion's configurable assets; its gameplay data is preserved.
• Remote servers are identified by an unambiguous supported Matcha registry signature. Unknown/unsupported content disables Matcha catalogue/assets rather than selecting a previous world's profile.
• Retains expanded advancements, the existing L shortcut, themed JEI buttons, presets and MezzConfig GUI settings support.

The datapack-priority rule selects Companion compatibility. Minecraft still controls which gameplay packs it loads; the Companion does not remove or rewrite a world's datapacks. Minecraft 26.3 and its Matcha target remain beta compatibility.