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Minecraft Java Edition datapacks can raise world height to Y = 2032 (used heavily by BuildTheEarth 1:1 alpine servers, mountain resorts, and megabuild projects), while Bedrock Edition clients hard-cap the Overworld at [-64, 320) ([-64, 512) with Geyser's extended height option). Above that ceiling, Bedrock players hit invisible air while Java players keep climbing.

Hauteur is a Geyser extension (dropped straight into Geyser's extensions/ folder—zero client mods or Bedrock add-ons required) that dynamically shifts a 16-block-aligned vertical window O per Bedrock player. Every Y coordinate sent to the Bedrock client is translated on the wire as Y - O, and every packet sent back is restored as Y + O, so a Java peak at Y = 1950 renders solidly in front of a Bedrock player.

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How Hauteur Works Under the Hood

	Mechanism
	Per-Player 16-Aligned Height Window (Y ± O) Maintains an independent subchunk-aligned offset O per Bedrock session (window-step: 128, margin-top: 96, margin-bottom: 96). As a player climbs, descends, or teleports, Hauteur shifts O automatically and keeps an action-bar readout (Real Y: 1952 (window +1664)) visible whenever O ≠ 0.
	Live Chunk Cache & Subchunk Re-Slicing Caches full-height Java chunks (-2032 .. 2031) alongside single-block, section, explosion, and piston updates—then re-slices and streams only the subchunks overlapping the player's new Bedrock window upon rebasing, prioritized radially from the player outward.
	400 ms Rebase Freeze & Packet Replay Briefly holds entity-motion deltas during a window transition (freeze-millis: 400) and replays them seamlessly at the new offset once the center chunks arrive, preventing Bedrock clients from falling into unloaded air mid-shift.
	Absolute-Y Teleport Command Rewriting Leaves absolute commands (/tp x 1950 z) untouched while translating relative ~ Y coordinates from the Bedrock client's shifted frame back to real Java world coordinates (tp, tppos, teleport).

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Diagnostic Commands

Aliases: /hauteur, /skywindow, /sw, /bho

Command	Description
/hauteur · /hauteur info [player]	Inspect current window offset O, real Java Y, Bedrock client Y, and cached chunk count
/hauteur watch [player]	Stream live window transitions for a player as they happen
/hauteur recent	Display the 10 most recent window shifts across the proxy/server
/hauteur doctor	Self-check reflection hooks, dimension ceilings, and config sanity
/hauteur stats	View cumulative shifts, chunk resends, and rebase timings since startup

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Installation & Honest Scope

1. Run Java 21+ and Geyser (2.9.x+ / 2.11.2-SNAPSHOT on Standalone, Paper/Purpur/Folia, Fabric, Velocity, or BungeeCord).
2. Enable extended-world-height: true in Geyser's config.yml for the widest [-64, 512) (576-block) Bedrock window.
3. Place Hauteur-<version>.jar into Geyser's extensions/ folder (never plugins/ or mods/) and restart (migrates legacy SkyWindow/ configs automatically).

Experimental Status & Known Protocol Limits

• Experimental: Built against Geyser's internal translator hooks—verify after updating Geyser with /hauteur doctor.
• 576-block vertical sightline: At any given instant, a Bedrock client sees the 576 vertical blocks inside its current window; terrain outside that slice appears as sky/void until the player moves toward it.
• Fast elytra climbs: Diving or rocketing across hundreds of Y levels per second triggers rapid ~400 ms rebase holds; tune cooldown-ticks and margin-top if your server is flight-heavy.

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Links & Support

• Source Code, Full Config Reference & Issues: GitHub — MaxLananas/Hauteur
• Community & Support: Join our Discord

_{Licensed under MIT}