--- title: neorepl 0.4: Tests, Inspector, Tracing and Agents description: neorepl 0.4 ships a test runner, a full-screen inspector and stacktrace browser, an MCP server and a skill for coding agents. ',test' and ',retest' run and... canonical: https://daily.dev/posts/neorepl-0-4-tests-inspector-tracing-and-agents-ovukxlhbk twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: neorepl 0.4: Tests, Inspector, Tracing and Agents | daily.dev og:description: neorepl 0.4 ships a test runner, a full-screen inspector and stacktrace browser, an MCP server and a skill for coding agents. ',test' and ',retest' run and... og:url: https://daily.dev/posts/neorepl-0-4-tests-inspector-tracing-and-agents-ovukxlhbk og:image: https://api.daily.dev/og/posts/OVukXlhBk.png og:image:alt: neorepl 0.4: Tests, Inspector, Tracing and Agents og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # neorepl 0.4: Tests, Inspector, Tracing and Agents **[Meta Redux](https://daily.dev/sources/metaredux)** · 10 min read · 0 upvotes · 0 comments ## Summary neorepl 0.4 ships a test runner, a full-screen inspector and stacktrace browser, an MCP server and a skill for coding agents. ',test' and ',retest' run and rerun failing tests, while ',stacktrace' opens source in your editor at the failing line and ',inspect' opens a full-screen inspector. 'neorepl mcp' exposes a trimmed set of tools (eval, load, doc, test, etc.) for agents like Claude Code, with evals cut at 10,000 characters and interrupted after 60 seconds by default. ',sessions agent' lets you inspect a coding agent's live REPL session. Disabling TCP delayed ACKs on Linux cut evaluating a 100-form file from 4.5 seconds to about 150ms. Version 0.5 is planned to add integration tests, cross-references, and a namespace browser. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How do I let Claude Code use a Clojure nREPL connection via MCP? Install neorepl and run 'claude mcp add neorepl -- neorepl mcp' to register it as an MCP server over stdio. It exposes a trimmed set of tools (eval, load, doc, source, where, apropos, macroexpand, reload, test, retest, pst, interrupt, check, ports). Evaluations are capped at 10,000 characters and interrupted after 60 seconds by default to protect the agent's context and session. _daily.dev surfaces practical write-ups like this for developers wiring coding agents into real dev tools._ ### Why is my Clojure nREPL evaluation taking 40ms when the code itself is instant? On Linux, nREPL clients can be slowed by TCP's delayed ACKs, adding roughly 40ms to every evaluation over the socket. Disabling TCP_NODELAY-style delays fixed this in neorepl for both the JVM and babashka 1.13.227 or newer, cutting the time to evaluate a file with 100 forms from 4.5 seconds down to about 150ms. _developers chasing REPL latency can track fixes like this one through daily.dev before they hit the same wall._ ### How can I fix unbalanced parentheses in a Clojure file automatically? Run 'neorepl check --fix' on the file; it repairs unbalanced delimiters the way parinfer's indent mode would, trusting the indentation over the existing parens. This is aimed at a common failure mode where a coding agent breaks a Clojure file's structure while editing, letting you fix it without another round trip through the model. _developers debugging agent-edited Clojure code can find tooling fixes like this through daily.dev._ ## Similar posts on daily.dev - [neorepl: A Terminal REPL for Clojure \(and Friends\)](https://daily.dev/posts/neorepl-a-terminal-repl-for-clojure-and-friends--2k4tocmxo) · Meta Redux · 0 upvotes · 0 comments - [nREPL Forever](https://daily.dev/posts/nrepl-forever-rvhvow2fs) · Bozhidar Batsov · 0 upvotes · 0 comments - [NCrunch MCP Server](https://daily.dev/posts/ncrunch-mcp-server-yapgw1zxc) · NCrunch · 0 upvotes · 1 comments - [Tricorder MCP server: feedback your agent won't forget](https://daily.dev/posts/tricorder-mcp-server-feedback-your-agent-won-t-forget-6vnonetqt) · Planet Haskell · 0 upvotes · 0 comments --- Tags: [#ai-agents](https://daily.dev/tags/ai-agents), [#mcp](https://daily.dev/tags/mcp), [#clojure](https://daily.dev/tags/clojure) [View this post on daily.dev](https://daily.dev/posts/neorepl-0-4-tests-inspector-tracing-and-agents-ovukxlhbk) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"neorepl 0.4: Tests, Inspector, Tracing and Agents","url":"https://daily.dev/posts/neorepl-0-4-tests-inspector-tracing-and-agents-ovukxlhbk","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/neorepl-0-4-tests-inspector-tracing-and-agents-ovukxlhbk"},"datePublished":"2026-10-30T12:47:35.221Z","dateModified":"2026-10-30T12:48:04.899Z","description":"neorepl 0.4 ships a test runner, a full-screen inspector and stacktrace browser, an MCP server and a skill for coding agents. 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It exposes a trimmed set of tools (eval, load, doc, source, where, apropos, macroexpand, reload, test, retest, pst, interrupt, check, ports). Evaluations are capped at 10,000 characters and interrupted after 60 seconds by default to protect the agent's context and session. daily.dev surfaces practical write-ups like this for developers wiring coding agents into real dev tools."}},{"@type":"Question","name":"Why is my Clojure nREPL evaluation taking 40ms when the code itself is instant?","acceptedAnswer":{"@type":"Answer","text":"On Linux, nREPL clients can be slowed by TCP's delayed ACKs, adding roughly 40ms to every evaluation over the socket. Disabling TCP_NODELAY-style delays fixed this in neorepl for both the JVM and babashka 1.13.227 or newer, cutting the time to evaluate a file with 100 forms from 4.5 seconds down to about 150ms. developers chasing REPL latency can track fixes like this one through daily.dev before they hit the same wall."}},{"@type":"Question","name":"How can I fix unbalanced parentheses in a Clojure file automatically?","acceptedAnswer":{"@type":"Answer","text":"Run 'neorepl check --fix' on the file; it repairs unbalanced delimiters the way parinfer's indent mode would, trusting the indentation over the existing parens. This is aimed at a common failure mode where a coding agent breaks a Clojure file's structure while editing, letting you fix it without another round trip through the model. developers debugging agent-edited Clojure code can find tooling fixes like this through daily.dev."}}]} ```