Support Matrix en

Support Matrix

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简体中文: Support-Matrix · English

Hassium covers Minecraft 1.20.1–1.21.11, adapted as 9 version segments × loaders. One segment per version; intra-segment versions are represented by an anchor compile.

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MC version × loader

Minecraft	Fabric	Forge	NeoForge
1.20.1	✅	✅	✅
1.20.2	✅	—	✅
1.20.3	✅	—	✅
1.20.4	✅	—	✅
1.20.5	✅	—	✅
1.20.6	✅	✅	✅
1.21.1	✅	✅	✅
1.21.2	✅	—	✅
1.21.3	✅	✅	✅
1.21.4	✅	✅	✅
1.21.5	✅	✅	✅
1.21.6	✅	✅	✅
1.21.7	✅	✅	✅
1.21.8	✅	✅	✅
1.21.9	✅	✅	✅
1.21.10	✅	✅	✅
1.21.11	✅	—	✅

• Forge is available on 1.20.1 / 1.20.6 / 1.21.1 / 1.21.3–1.21.10; 1.21.2 is skipped upstream (no official Forge userdev), 1.21.11 is sunset — use NeoForge for 1.21.x
• Forge support on 1.20.1 is provided by the neoforge subproject (loom.platform=forge); the standalone forge subproject builds only 1.20.6 / 1.21.x
• Forge 1.20.6 keeps a one-off Forge Config API Port bridge because it shares ModConfigSpec with NeoForge

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Nine-segment anchors (compile matrix)

Each segment is represented by one anchor that participates in compile and self-checks:

Segment	Anchor	Other versions in segment	Key change (summary)
A	1.20.1	—	Baseline: legacy networking + all legacy APIs
B	1.20.2	1.20.3	CustomPayload plumbing; NeoForge package rename
C	1.20.5	1.20.6	StreamCodec; Packet.write etc. removed
D	1.21.1	—	DisconnectionDetails; RL constructor privatized
E	1.21.2	1.21.3, 1.21.4	SerializableChunkData, lookupOrThrow
F	1.21.5	—	CompoundTag API; ProtocolInfo Unbound split; client cache not cross-MC-version compatible
G	1.21.6	1.21.7, 1.21.8	serverLevel()→level(); Connection.send listener; NeoForge EBS bus removed
H	1.21.9	1.21.10	LevelChunkSection; getServer() removed; setLevel one-arg
I	1.21.11	—	ResourceLocation → Identifier

Each anchor participates in compile and self-checks; the rest of the segment ships as releases, segmented via Manifold #if MC_VER in a single source tree.

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Client cache cross-version policy

From segment F (1.21.5) onward, the client chunk cache is not guaranteed to be cross-MC-version compatible:

• Within the same MC version (incl. Fabric ↔ NeoForge) hits and overwrites work normally
• After a version bump, the old cover is lazily overwritten (MISS → refetch → persist); no full invalidate on start
• No cross-version migration / format negotiation is implemented

See Compatibility.

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Repo and build

• Repo: https://github.com/limuqy/Hassium
• Build system: Architectury Loom + Manifold; versionProperties/<ver>.properties controls per-version dependencies
• Anchor compile (developer): ./gradlew compileAnchors
• Version boundary scan: ./gradlew scanVersionBoundaries

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