langchain-ai/langchain

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The agent engineering platform.

Stars: 147k
Forks: 24.5k
Open beginner issues: 38
Indexed issues: 431
Avg merge: 12h 34m
Merged PRs (30d): 176

Dominant language: Python
License: MIT
Last GitHub push: Sep 18, 2026
Latest indexed: Sep 18, 2026
Contributing guide: Contributing guide
Code of conduct: Code of conduct
Beginner labels: help wanted

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431 open issues indexed

langchain-typesafe: ModelRouterMiddleware raises an opaque RuntimeError when state has no human message Open

bug external typesafe

Difficulty 2/5 1-3 hours Newbie friendliness 68/100

langchain-ai/langchain#40651 · 1 comment · Opened Sep 18, 2026
ntegration: memory transfer store for LangChain/LangMem export and import verified agent memory Open

anthropic chroma core deepseek exa feature request fireworks groq huggingface langchain langchain-classic mistralai model-profiles nomic ollama openai perplexity qdrant standard-tests text-splitters

Difficulty 5/5 Over a week Newbie friendliness 25/100

langchain-ai/langchain#40616 · Opened Sep 18, 2026
core: AIMessage(tool_calls=[]) still hydrates tool calls from additional_kwargs Open

bug core external

Difficulty 2/5 1-3 hours Newbie friendliness 76/100

langchain-ai/langchain#40609 · 3 comments · Opened Sep 18, 2026
core: `InMemoryRecordManager.list_keys(limit=0)` returns all keys instead of an empty list Open

bug core external

Difficulty 2/5 1-3 hours Newbie friendliness 88/100

langchain-ai/langchain#40592 · 4 comments · Opened Sep 18, 2026
`ChatGroq` accepts `n > 1` for non-streaming requests although Groq only supports `n=1 Open

bug external groq

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

langchain-ai/langchain#40590 · 4 comments · Opened Sep 18, 2026
[Bug] Two langchain unit tests read pyproject.toml without a UTF-8 encoding and fail on Windows with a non-UTF-8 locale Open

bug external langchain

Difficulty 2/5 1-3 hours Newbie friendliness 88/100

langchain-ai/langchain#40588 · 2 comments · Opened Sep 18, 2026
feat(typesafe): add `ModerationMiddleware` for input content moderation Open

external feature request typesafe

Difficulty 5/5 Over a week Newbie friendliness 45/100

langchain-ai/langchain#40578 · 2 comments · Opened Sep 18, 2026
ChatOpenAI silently drops provider-specific extra fields on tool calls (breaks multi-turn tool calling against OpenAI-compatible endpoints) Open

bug external openai

Difficulty 3/5 1-2 days Newbie friendliness 72/100

langchain-ai/langchain#40563 · 2 comments · Opened Sep 17, 2026
core: `finalize_tool_call_chunk` coerces `id=None` to `""`, collapsing parallel id-less tool calls Open

bug core external

Difficulty 3/5 1-2 days Newbie friendliness 68/100

langchain-ai/langchain#40531 · 9 comments · Opened Sep 16, 2026
UsageMetadataCallbackHandler silently drops usage_metadata when model_name is missing Open

bug core external standard-tests

Difficulty 2/5 1-3 hours Newbie friendliness 35/100

langchain-ai/langchain#40518 · 3 comments · Opened Sep 16, 2026
MCP ResourceLink/EmbeddedResource metadata dropped when converting to LangChain content blocks (langchain.mcp) Open

bug external langchain

Difficulty 3/5 1-2 days Newbie friendliness 78/100

langchain-ai/langchain#40503 · 3 comments · Opened Sep 16, 2026
core: `InMemoryVectorStore` raises `NotImplementedError` for relevance-score search and the `similarity_score_threshold` retriever Open

bug core external

Difficulty 3/5 1-2 days Newbie friendliness 75/100

langchain-ai/langchain#40502 · 2 comments · Opened Sep 16, 2026
core: `AsyncBaseTracer` drops `name` in `on_tool_start` and `response` in `on_llm_error`, diverging from `BaseTracer` Open

bug core external

Difficulty 3/5 1-2 days Newbie friendliness 78/100

langchain-ai/langchain#40501 · 2 comments · Opened Sep 16, 2026
langchain 1.4.0: any after_model middleware using documented `jump_to="tools"` bypasses the HITL pending_tool_calls gate and re-executes rejected tool calls Open

bug external langchain

Difficulty 4/5 3-5 days Newbie friendliness 48/100

langchain-ai/langchain#40492 · 3 comments · Opened Sep 16, 2026
langchain: preserve result-level MCP `_meta` in tool results Open

internal mcp

Difficulty 3/5 1-2 days Newbie friendliness 65/100

langchain-ai/langchain#40470 · 1 comment · Opened Sep 16, 2026
core: mustache inverted section `{{^key}}` nested inside a `{{#key}}` list section misrenders or raises `IndexError` Open

bug core external

Difficulty 3/5 1-2 days Newbie friendliness 82/100

langchain-ai/langchain#40460 · 4 comments · Opened Sep 15, 2026
huggingface: `HuggingFaceEndpoint` drops the token for dedicated Inference Endpoints (`*.endpoints.huggingface.cloud`) Open

bug external huggingface

Difficulty 2/5 1-3 hours Newbie friendliness 88/100

langchain-ai/langchain#40447 · 3 comments · Opened Sep 14, 2026
Token budget middleware that checks in with the user instead of hard-stopping Open

core external feature request langchain

Difficulty 5/5 Over a week Newbie friendliness 35/100

langchain-ai/langchain#40444 · 2 comments · 1 reaction · Opened Sep 14, 2026
Blob leaks a UTF-8 BOM into as_string() Open

bug core external

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

langchain-ai/langchain#40441 · 7 comments · Opened Sep 14, 2026
langchain-openrouter: ToolMessage content blocks (e.g. images) are sent to the API unconverted, failing client-side with ValidationError Open

bug external openrouter

Difficulty 2/5 1-3 hours Newbie friendliness 84/100

langchain-ai/langchain#40435 · 2 comments · Opened Sep 13, 2026
[Security Hardening] Mitigating OWASP LLM01 Indirect Prompt Injections in Web Loaders via CSS Render-Layer Obfuscation (CWE-1427) Open

external feature request langchain

Difficulty 5/5 Over a week Newbie friendliness 35/100

langchain-ai/langchain#40431 · 2 comments · Opened Sep 13, 2026
core: content_blocks raises TypeError on a v0 multimodal block that carries an id Open

bug core external

Difficulty 2/5 1-3 hours Newbie friendliness 30/100

langchain-ai/langchain#40424 · 3 comments · Opened Sep 12, 2026
bug(langchain): create_agent ends the loop on an invalid structured-output call when an ordinary tool call is in the same batch (no retry feedback) Open

bug core external langchain

Difficulty 3/5 1-2 days Newbie friendliness 76/100

langchain-ai/langchain#40423 · 2 comments · Opened Sep 12, 2026
BaseLLM cache ignores per-call generation options and replays the wrong completion Open

bug core external openai

Difficulty 3/5 1-2 days Newbie friendliness 35/100

langchain-ai/langchain#40403 · 3 comments · Opened Sep 11, 2026
Bug: MCPAdapter test fails on Windows due to strict POSIX error assertion Open

bug external langchain

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

langchain-ai/langchain#40396 · 4 comments · Opened Sep 11, 2026
v3 stream: parallel tool calls collide on the positional fallback key and one is silently dropped Open

bug core external

Difficulty 2/5 1-3 hours Newbie friendliness 76/100

langchain-ai/langchain#40392 · 6 comments · Opened Sep 11, 2026
ChatOpenRouter: max_retries=0 enables the SDK default retry policy Open

bug external openrouter

Difficulty 2/5 1-3 hours Newbie friendliness 75/100

langchain-ai/langchain#40379 · 2 comments · Opened Sep 10, 2026
RemoteGraph returns invoke output as list of dict instead of list of BaseMessage - mandatory when combined with CompiledSubAgent Open

bug external langchain

Difficulty 4/5 3-5 days Newbie friendliness 45/100

langchain-ai/langchain#40368 · 1 comment · Opened Sep 10, 2026
Fireworks: reasoning_content dropped in streaming and outbound converters Open

bug external fireworks langchain

Difficulty 2/5 1-3 hours Newbie friendliness 35/100

langchain-ai/langchain#40367 · 1 comment · Opened Sep 10, 2026
Errors OpenRouter reports in a 200 response body are stringified rather than classified Open

bug external openrouter

Difficulty 3/5 1-2 days Newbie friendliness 78/100

langchain-ai/langchain#40364 · 1 comment · Opened Sep 10, 2026
Provider errors returned in a 200 response body are never classified Open

bug external openai

Difficulty 4/5 3-5 days Newbie friendliness 52/100

langchain-ai/langchain#40362 · 1 comment · Opened Sep 10, 2026
CommaSeparatedListOutputParser corrupts quoted CSV fields across streaming chunks Open

bug core external

Difficulty 3/5 1-2 days Newbie friendliness 76/100

langchain-ai/langchain#40360 · 2 comments · Opened Sep 10, 2026
langchain: MCP adapter test asserts a POSIX-only error message, fails on Windows where the drive letter parses as a URL scheme Open

bug external langchain

Difficulty 1/5 Under an hour Newbie friendliness 92/100

langchain-ai/langchain#40354 · 1 comment · Opened Sep 10, 2026
standard-tests: chat model tests never check the documented `total_tokens == input_tokens + output_tokens` invariant Open

bug external standard-tests

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

langchain-ai/langchain#40343 · 1 comment · Opened Sep 9, 2026
`HTMLHeaderTextSplitter` raises `ValueError` on init for the non-heading tags its splitter already supports Open

bug external text-splitters

Difficulty 2/5 1-3 hours Newbie friendliness 35/100

langchain-ai/langchain#40341 · 10 comments · Opened Sep 9, 2026
Feature: Support metadata-only updates in index() - avoid re-embedding when the content is unchanged Open

core external feature request

Difficulty 5/5 Over a week Newbie friendliness 35/100

langchain-ai/langchain#40334 · 1 comment · Opened Sep 9, 2026
feat: WalletForge x402 paid tools (fetch_markdown / normalize_text) for LangChain agents Open

external feature request langchain

Difficulty 4/5 3-5 days Newbie friendliness 35/100

langchain-ai/langchain#40333 · Opened Sep 9, 2026
`convert_to_openai_tool` ignores `strict` for dicts already in OpenAI tool format Open

bug core external

Difficulty 3/5 1-2 days Newbie friendliness 74/100

langchain-ai/langchain#40332 · 2 comments · Opened Sep 9, 2026
langchain: 26 shell middleware unit tests fail on Windows (POSIX-only tests without platform guards) Open

bug external langchain

Difficulty 2/5 1-3 hours Newbie friendliness 84/100

langchain-ai/langchain#40320 · 1 comment · Opened Sep 9, 2026
MarkdownHeaderTextSplitter becomes very slow with many paragraphs under the same header Open

bug external text-splitters

Difficulty 2/5 1-3 hours Newbie friendliness 76/100

langchain-ai/langchain#40314 · 2 comments · Opened Sep 9, 2026
`AnthropicPromptCachingMiddleware` silently drops the system prompt when the last content block is a string Open

anthropic bug external

Difficulty 2/5 1-3 hours Newbie friendliness 84/100

langchain-ai/langchain#40311 · 2 comments · Opened Sep 9, 2026
text-splitters: `RecursiveCharacterTextSplitter` skips `strip_whitespace` for pieces it cannot split further Open

bug external text-splitters

Difficulty 2/5 1-3 hours Newbie friendliness 30/100

langchain-ai/langchain#40299 · 3 comments · Opened Sep 8, 2026
text-splitters: `MarkdownHeaderTextSplitter` keeps the closing `##` sequence in header metadata Open

bug external text-splitters

Difficulty 2/5 1-3 hours Newbie friendliness 25/100

langchain-ai/langchain#40298 · 4 comments · Opened Sep 8, 2026
core: `parse_json_markdown` fails on a fence tagged `JSON` instead of `json` Open

bug core external

Difficulty 2/5 1-3 hours Newbie friendliness 35/100

langchain-ai/langchain#40297 · 3 comments · Opened Sep 8, 2026
ChatDeepSeek translates `JSONDecodeError` on the sync path only — `ainvoke` / `astream` leak the raw "Expecting value" Open

bug deepseek external

Difficulty 2/5 1-3 hours Newbie friendliness 35/100

langchain-ai/langchain#40281 · 3 comments · Opened Sep 8, 2026
text-splitters: SpacyTextSplitter ignores max_length with pipeline="sentencizer" Open

bug external text-splitters

Difficulty 2/5 1-3 hours Newbie friendliness 85/100

langchain-ai/langchain#40279 · 2 comments · Opened Sep 8, 2026
core: SSRF-safe transports drop streaming request bodies and crash on internationalized hostnames Open

bug core external

Difficulty 3/5 1-2 days Newbie friendliness 68/100

langchain-ai/langchain#40278 · 1 comment · Opened Sep 8, 2026
`MCPAdapter` resume fails when a new initial call receives a new elicitation key Open

bug external langchain

Difficulty 4/5 3-5 days Newbie friendliness 55/100

langchain-ai/langchain#40263 · 2 comments · Opened Sep 7, 2026
ContextEditingMiddleware blocks the event loop with model-based token counting Open

bug external langchain

Difficulty 3/5 1-2 days Newbie friendliness 72/100

langchain-ai/langchain#40261 · 2 comments · Opened Sep 7, 2026
Retry jitter can cause delays to exceed `max_delay` Open

bug external langchain

Difficulty 2/5 1-3 hours Newbie friendliness 84/100

langchain-ai/langchain#40259 · 3 comments · Opened Sep 7, 2026

langchain-ai/langchain

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