{"categories":[{"label":"Artificial Intelligence","url":"https://skillfed.io/packages/category/scientific-engineering-artificial-intelligence/7"}],"enrichment":{"capability":"Adds a persistent, sandboxed JavaScript REPL tool to deepagents agents, letting the model write orchestrated JavaScript code instead of issuing serial tool calls.","skillfed_tags":["agent-middleware","javascript-sandbox","orchestration"],"use_cases":["Loop over a list and call tools per item without round-tripping to the model between iterations.","Run multiple independent tool calls concurrently using Promise.all and orchestrate filtering or aggregation in one eval.","Dispatch multiple subagents in parallel, filter results, and synthesize them in JavaScript before returning to the parent.","Compute intermediate state between tool calls (aggregate, dedupe, format) without leaving the REPL.","Reuse state across several turns by persisting variables and functions in thread mode."],"what_it_does":"langchain-quickjs is a middleware for deepagents that injects a persistent, sandboxed JavaScript REPL into an agent's tool set. Instead of the model issuing N serial tool calls, it can write one JavaScript block that orchestrates work in-loop\u2014variables and functions persist across calls, Promise.all runs concurrent work, and configured subagents are dispatchable as await task({...}). The REPL runs in a QuickJS context with no ambient capabilities (no filesystem, network, or real clock), but can explicitly call into the agent's own tools via programmatic tool calling (PTC).\n\nThe middleware registers an eval tool, appends a system-prompt snippet explaining sandbox semantics, and gives each LangGraph thread_id its own QuickJS Runtime so conversations remain isolated. Persistence modes control how far state reaches: thread (default, survives across turns), turn (within a turn only), or call (fresh per eval). Each call has a wall-clock timeout (default 5 s) and the runtime has a shared memory limit (default 64 MiB); PTC calls are budgeted at 256 per eval by default. Results and console output are independently truncated before returning to the model.","worth_installing":"Yes, if you are building deepagents-based agents and need to reduce model round-trips for orchestrated tool use. The low install friction, active maintenance, and permissive MIT license make it a straightforward addition. The 16-day-old release and alpha status mean expect occasional breaking changes; verify that the default timeouts and memory limits suit your workload before production use."},"id":"langchain-quickjs","links":{"html":"https://skillfed.io/packages/langchain-quickjs","md":"https://skillfed.io/packages/langchain-quickjs.md","pypi":"https://pypi.org/project/langchain-quickjs/"},"maintenance":{"status":"active"},"meta":{"latest_release":"2026-07-29","license_spdx":null,"license_treatment":"permissive","name":"langchain-quickjs","python_support":"supports_current","summary":"JavaScript REPL middleware for deepagents"},"popularity":{"monthly_downloads":198124,"position":9739,"tier":"top_15000"},"security":{"n_vulnerabilities":0},"version":"0.3.5"}