wait-for-lsp

wait-for-lsp

LSP proxy that filters stale textDocument/publishDiagnostics between Claude Code and any LSP server, preventing fix loops caused by outdated diagnostics.

How it works

Claude Code  ←→  wait-for-lsp  ←→  rust-analyzer (or any LSP server)

The proxy sits between Claude Code and the LSP server, forwarding all messages transparently except publishDiagnostics. Diagnostics are filtered through three layers:

1. Diagnostic Drop (STAY_FRESH_DROP_DIAGNOSTICS=true) — drops all diagnostics (default for safety)
2. Severity Filter (STAY_FRESH_MIN_SEVERITY=1) — keeps only diagnostics at or below the threshold
3. Version Tracking (STAY_FRESH_STALE_FILTER=true) — tracks didOpen/didChange versions per URI; drops publishDiagnostics older than the tracked version
4. Dedup Queue — buffers per-URI; only the latest diagnostic per URI per read cycle reaches the client

Stable-filter mode (recommended)

Set these env vars to pass all diagnostics but drop stale ones:

STAY_FRESH_DROP_DIAGNOSTICS=false
STAY_FRESH_MIN_SEVERITY=4
STAY_FRESH_STALE_FILTER=true   # default

This means: if you edit a file and rust-analyzer starts re-analyzing, intermediate/incremental diagnostics from the previous state are dropped. You only see the final, correct diagnostic state after re-analysis completes.

Installation

Pre-built binary (recommended)

Download the latest binary from GitHub Releases. Extract and place wait-for-lsp somewhere on your $PATH.

From source

cargo install --git https://github.com/TonyWu20/wait-for-lsp

Plugin

Install the plugin from the my-claude-marketplace to register wait-for-lsp as the LSP proxy for Rust, Python, and Fortran. Then disable the official language server plugins to avoid conflicts:

claude plugin disable rust-analyzer-lsp@claude-plugins-official --scope user
claude plugin disable pyright-lsp@claude-plugins-official --scope user

Env vars

Variable	Default	Description
STAY_FRESH_DROP_DIAGNOSTICS	true	Drop all diagnostics (kill switch)
STAY_FRESH_MIN_SEVERITY	1	Max severity to keep (1=Error..4=Hint)
STAY_FRESH_STALE_FILTER	true	Version-based stale detection
STAY_FRESH_LOG	false	Debug logging to stderr