UE Knowledge Base — a local semantic knowledge base for UE developers

A local semantic knowledge base for UE development: 86 original documents (81 English, 5 bilingual), indexed with BGE embeddings + ChromaDB. Download the ~100MB model once, then search fully offline on a laptop CPU — no API costs.

Why this exists

Covers: Gameplay Ability System, character movement, animation, AI navigation, networking/replication, UMG/Slate, Niagara, Mass Entity, State Trees, PCG, materials/rendering, module build system, editor tools, and more (full 31-topic list under knowledge/).

Highlights

• 86 original docs (81 English, 5 bilingual), indexed into 1,455 searchable chunks — content distilled from actual project work
• Real query → top-1 at 75.1% similarity (see actual output below)
• No API key, no tokens, no server — pip install and go
• Embedding + retrieval happen locally; code never leaves your machine
• Every command supports --json; patterns for Hermes / Claude Code / OpenCode / any custom pipeline
• China-friendly: GitHub mirror clone + Tsinghua PyPI + automatic hf-mirror fallback — no proxy needed
• ~100MB model, laptop CPU, no GPU; index build ~1 min

Quick start

pip install ue-knowledge-base   # install

ue-kb download-model            # one-time ~100MB model (auto-falls back to hf-mirror)
ue-kb build                     # build the index (~1 min, fully offline from here)
ue-kb query "GAS ability cooldown"
ue-kb query "Niagara particle collision" --json   # JSON output for agents

Real query output

$ ue-kb query "GAS ability cooldown"
🔍 UE 知识库检索：GAS ability cooldown

[1] ue-gameplay-abilities/references/gas-input-integration.md › 问题 (匹配度: 75.1%)
    ## 问题  UE 项目同时使用 GAS (GameplayAbilitySystem) 和 Enhanced Input 时，
    容易陷入两个极端：- **全 GAS** → 所有输入走 GAS，但 WASD 轴输入不适合 GAS 的
    事件模型，且 `CommitAbility` 的 GC 延迟影响跳跃手感 - **全直调** → 绕过 GAS，
    失去标签阻断、冷却、属性驱动的 BUFF/DEBUFF...
[2] ue-animation-system/SKILL.md › GAS Integration — PlayMontageAndWait (匹配度: 74.5%)
    ### GAS Integration — PlayMontageAndWait
    ```cpp // GAS ability task — PlayMontageAndWait (requires GameplayAbilities module)
    UAbilityTask_PlayMontageAndWait* Task = UAbilityTask_PlayMontageAndWai...

Hits include usable C++ patterns, not just related text.

Install in mainland China (zero proxy)

# 1. Get the code (GitHub mirrors, pick either)
git clone --depth 1 https://gh-proxy.com/https://github.com/dong273/ue-knowledge-base.git
#   git clone --depth 1 https://ghfast.top/https://github.com/dong273/ue-knowledge-base.git

# 2. Install dependencies (Tsinghua PyPI mirror)
pip install -e . -i https://pypi.tuna.tsinghua.edu.cn/simple

# 3. Download the model (mirror fallback is automatic)
ue-kb download-model

# 4. Build the index (fully local; offline from here on)
ue-kb build

# 5. Search
ue-kb query "GAS ability cooldown"

CLI reference

Python API

from ue_knowledge.query import query

for hit in query("GAS cooldown", top_k=5):
    print(hit["source"], hit["heading"], hit["score"])   # source, heading, similarity

Agent integration

ue-kb is built for AI agents: fully offline, zero cost per query, --json on every command. Integration examples in docs/agent-integration.md:

• Hermes Agent skill wrapper (expose the search as an agent tool)
• Claude Code slash command
• OpenCode command
• Plain Python snippet for any custom pipeline

Extending the corpus

You can extend the corpus:

1. Add a markdown file under knowledge/<topic>/ (##/### headings — the indexer chunks on heading boundaries);
2. ue-kb build --append — no full rebuild needed;
3. Or index any local .md directory: ue-kb build --source my-docs/.

For indexing Unreal Engine C++ header comments or Epic official docs, see scripts/index_engine_source.py and scripts/crawl_epic_docs.py (they expect local engine/UE paths — extracted index data is generated locally and not redistributed, out of respect for Epic's copyright).

FAQ

• Windows: Cannot open header file when querying? — hnswlib cannot open its index files under non-ASCII paths (Chinese usernames/folders). The CLI rejects such paths up front: use a pure-ASCII index directory, e.g. ue-kb build --db C:/uekb/.chroma_db. The corpus itself may stay anywhere.
• Slow model download in mainland China? — ue-kb download-model automatically retries via hf-mirror.com when the official source fails; no proxy or manual HF_ENDPOINT needed.
• Index ready but queries say the index is missing? — the index directory was moved/deleted, or a chromadb upgrade changed the format. Rebuild with ue-kb build --force (chromadb>=0.5,<1.0 is pinned to avoid the 1.x Rust backend that cannot reload its own HNSW index).
• Telemetry noise on stderr? — chromadb 0.6.x product telemetry is disabled at the settings level (anonymized_telemetry=False), so no posthog lines are printed regardless of the installed posthog version.

License

MIT. The knowledge documents are original writing; no engine source code or verbatim Epic documentation is included.