Agent skill · software engineering · jeremylongshore
langchain-data-handling
Load and chunk documents for LangChain 1.0 RAG pipelines correctly \u2014\
Why this skill is useful
Provides specific commands and strategies for handling document loading and chunking in LangChain that are not widely known.
What it needs
Requires beautifulsoup4, datasketch, pymupdf, python, requests, unstructured installed locally. About 8k tokens when loaded. Last updated 2026-08-07. 2,604 stars on the source repository.
What this skill does
LangChain Data Handling — Loaders and Splitters (Python) Overview You have a RAG system over a Python docs site. A user asks "what does trimmessages do?" and the retriever returns this chunk: ...and that's it. The chunk ends there. The code example showing the function body — the actual thing the user wanted — is in a different chunk, retrieved with a lower similarity score and dropped before the LLM sees it. The model then hallucinates the function's behavior from the signature alone. This is pain-catalog entry P13. RecursiveCharacterTextSplitter's default separators are ["\n\n", "\n", " ", ""]. It splits on any blank line — including inside triple-backtick code fences in Markdown. The fix is a one-line swap to RecursiveCharacterTextSplitter.fromlanguage(Language.MARKDOWN), which treats the fence as an atomic unit, but you have to know the bug exists. The sibling failures this skill prevents: P49 — PyPDFLoader splits by page. A 5-row financial table that spans a page break gets torn in half; rows 1-3 go in one chunk, rows 4-5 in another with no header. A RAG answer sourced from the second chunk misquotes the numbers because the column meanings are in the first chunk. Fix: use PyMuPDFLoader or UnstructuredPDFLoader, which detect tables and emit them as distinct structured elements. P50 — WebBaseLoader's default User-Agent is python-requests/2.x. Cloudflare-protected sites flag this as a bot and return a 403 interstitial HTML page ("Checking your browser...") instead of real content. The crawler indexes the challenge page. You notice weeks later when every retrieval from that source returns the same Cloudflare text. Fix: set a realistic headertemplate={"User-Agent": "Mozilla/5.0 ..."}, respect robots.txt, and rate-limit per-host to 1 req/sec. Pinned versions: langchain-core 1.0.x, langchain-community 1.0.x, langchain-text-splitters 1.0.x, pymupdf, unstructured. Pain-catalog anchors: P13, P49, P50, P15. …
How to use it
Reference it in AdaL, Claude Code, Cursor or any coding agent — nothing to install:
@skills jeremylongshore/langchain-data-handling--54e969