stay-fresh-lsp-proxy

stay-fresh-lsp-proxy

Stop stale LSP diagnostics from derailing your Claude Code sessions.

Note: This is a temporary workaround for issues with how Claude Code handles LSP diagnostics. Once the underlying problems are fixed upstream, this plugin will no longer be necessary. Relevant issues:

• LSP output displays stale diagnostics after file changes (#17979)
• pyright-lsp plugin promotes hint-level DiagnosticTag.Unnecessary into conversation context (#26634)
• TypeScript LSP plugin scans file paths in user prompt text, injecting unwanted diagnostics (#28562)

The Problem

Claude Code's LSP plugins fire textDocument/publishDiagnostics after every edit. The diagnostics arrive from the previous state of the file — not the current one. Claude sees these stale errors, thinks the code is broken, and tries to "fix" problems that don't exist. This leads to:

• Unnecessary reverts — Claude undoes correct work because a stale diagnostic says there's an error
• Fix loops — Claude chases phantom type errors that would resolve on their own after the next save
• Wasted turns — every edit triggers a round of outdated warnings that Claude has to reason about

The root cause is a timing issue: diagnostics lag behind edits, so Claude is always reacting to the previous state of your code.

How It Works

stay-fresh-lsp-proxy sits between Claude Code and your LSP server. It forwards everything normally (go-to-definition, hover, references, completions) but intercepts textDocument/publishDiagnostics notifications and filters them before they reach Claude. No stale diagnostics, no confused AI.

Quick Install

npx stay-fresh-lsp-proxy setup --typescript --python --rust

Pick only the languages you need:

npx stay-fresh-lsp-proxy setup --typescript              # Just TypeScript/JS
npx stay-fresh-lsp-proxy setup --typescript --python     # TypeScript + Python
npx stay-fresh-lsp-proxy setup --rust                    # Just Rust

This will:

1. Register the plugin marketplace with Claude Code
2. Install per-language plugins and disable conflicting official LSP plugins
3. Enable the LSP tool in Claude Code settings

Supported Languages

Language	LSP Server	Install the server
TypeScript/JS	typescript-language-server	npm i -g typescript-language-server typescript
Python	pyright-langserver	npm i -g pyright
Rust	rust-analyzer	rustup component add rust-analyzer

The setup script will warn you if the required LSP server binary is not found in your PATH.

Configuration

Control filtering behavior with environment variables. Set them in ~/.claude/settings.json under env:

{
  "env": {
    "STAY_FRESH_DROP_DIAGNOSTICS": "true",
    "STAY_FRESH_MIN_SEVERITY": "1",
    "STAY_FRESH_LOG": "false"
  }
}

Configuration Reference

Variable	Default	Description
STAY_FRESH_DROP_DIAGNOSTICS	true	Drop all diagnostics. Set to false to use severity filtering instead.
STAY_FRESH_MIN_SEVERITY	1	When not dropping all, the maximum severity level to keep. 1 = only errors, 2 = errors + warnings, 3 = errors + warnings + info, 4 = everything (same as no filter).
STAY_FRESH_LOG	false	Enable debug logging to $TMPDIR/stay-fresh-lsp-proxy/.

Recipes

Drop everything (default) — The nuclear option. Eliminates all stale diagnostics completely. Claude keeps full LSP intelligence (go-to-definition, hover, etc.) but never gets misleading error reports mid-edit.

{
  "env": {
    "STAY_FRESH_DROP_DIAGNOSTICS": "true"
  }
}

Errors only — Let genuine errors through (type mismatches, missing imports, syntax errors) but suppress warnings, hints, and info. Good if you want Claude to catch real breakage while ignoring the noise.

{
  "env": {
    "STAY_FRESH_DROP_DIAGNOSTICS": "false",
    "STAY_FRESH_MIN_SEVERITY": "1"
  }
}

Errors + Warnings — Also keep warnings (unused variables, deprecated APIs) but drop hints and info. You'll still get some stale notifications, but you're trading that off against Claude occasionally catching real issues it wouldn't otherwise notice.

{
  "env": {
    "STAY_FRESH_DROP_DIAGNOSTICS": "false",
    "STAY_FRESH_MIN_SEVERITY": "2"
  }
}

Everything except hints — Only drop hint-level diagnostics (like pyright's "unnecessary" markers that prompted #26634). Closest to stock behavior with the worst offenders removed.

{
  "env": {
    "STAY_FRESH_DROP_DIAGNOSTICS": "false",
    "STAY_FRESH_MIN_SEVERITY": "3"
  }
}