LangChain

Recently shipped Fleet agent file deletion, OAuth completion for MCP servers, and deprecated legacy feedback formulas. Also added annotation queue item endpoints and refreshed model profiles.

Fleet agents gained a file delete tool — Agents can now remove files from their memory and skills, including files in linked workspace skills. Core agent files and read-only system skills stay protected.

OAuth flow completed for MCP servers with client-secret auth — Connecting these servers no longer fails after the consent step.

New annotation queue item endpoints — Added endpoints for adding, listing, updating, deleting, counting, positioning, and reviewing run/thread queue items. Legacy endpoints were marked deprecated with a sunset date of January 31, 2027.

Observability and evaluations

• Legacy feedback formula endpoints deprecated — POST/GET /feedback/formulas and related endpoints are replaced by composite evaluators (code evaluator plus run rule), with removal scheduled for 2026-08-20.
• Experiment table chips now lay out from real measurements — Model, prompt, and tool chips show accurate truncation, and the +N overflow badge is a clickable dropdown with filter, group by, open in playground, and details actions.
• Code evaluator upload accepts PEP 604 union return types — Entrypoints like -> dict | None are now supported. Repetition run tree expansion also works reliably when a repetition root has a project ID but no session ID.
• Evaluator score corrections now update immediately — Dataset experiment tables can also sort by feedback score with SmithDB queries enabled.

Gateway and security fixes

• LangSmith Gateway environment config added to JS chat models — OpenAI, Anthropic, and Fireworks chat models now support it, matching the earlier Python fallback to LANGSMITH_API_KEY.
• langchain-openai 1.4.2 handles ContextWindowExceededError and redacts MCP authorization.
• SDK security patches — Fixed URL path injection in the Python Sandbox client, sanitized git remote credentials, and escaped insights report HTML.

Checkpointing updates — langgraph-checkpoint 4.2.0 adds opt-in omit_expired to skip expired rows on read; checkpoint-postgres 3.1.2 fixes finding plain-value seeds when walking delta history.