LSP plugins spawn eagerly regardless of file types in project

Summary

All enabled LSP plugins spawn immediately at session start, ignoring extensionToLanguage mappings in plugin configs. LSPs should start lazily when a matching file is first read or edited.

Environment

• Claude Code version: 2.1.29
• OS: Arch Linux 6.18.3

Steps to Reproduce

# 1. Create empty directory
cd $(mktemp -d)

# 2. Start Claude session
claude -p "hello"

# 3. Check running LSPs
pgrep -a "clangd|rust-analyzer|gopls|pyright"

Expected: No LSPs spawn (no matching source files)
Actual: All enabled LSPs spawn immediately

Test Results

Started session in directory with zero source files:

$ pgrep -a "clangd|rust-analyzer|gopls|pyright"
clangd --background-index
rust-analyzer
gopls
pyright-langserver --stdio

Behaviors Tested

| Scenario | Expected | Actual |
|----------|----------|--------|
| Session in empty dir | No LSPs spawn | All enabled LSPs spawn |
| Session in JS-only project | Only TS LSP spawns | All enabled LSPs spawn |
| Read a .rs file | rust-analyzer starts | Already running |
| Plugin disabled in settings | LSP doesn't spawn | ✓ Works correctly |

Temp Directory Pollution

LSPs create temp directories even when never used:

| LSP | Temp Dirs Created | Disk Usage |
|-----|-------------------|------------|
| pyright | 16 | 0 (empty) |
| proc-macro-srv (rust-analyzer) | 9 | 0 |
| intelephense (PHP) | 1 | 6.9MB |
| lua-language-server | 1 | 4.5MB |

Proposed Solution

Start LSPs lazily based on extensionToLanguage mappings:

• When a file with a mapped extension is first read/edited, start the corresponding LSP
• Respect the plugin config's extension mappings

Workaround

Disable unused LSP plugins in ~/.claude/settings.json:

{
  "permissions": {
    "plugins": {
      "lua-lsp@claude-plugins-official": false,
      "rust-analyzer@claude-plugins-official": false
    }
  }
}

---

Resource Impact

| LSP | Memory | Temp Disk | CPU at Idle |
|-----|--------|-----------|-------------|
| rust-analyzer | ~150MB | 0 | ~2% |
| clangd | ~100MB | 0 | ~1% |
| pyright | ~80MB | 0 | ~1% |
| gopls | ~60MB | 0 | ~1% |
| lua-language-server | ~50MB | 4.5MB | ~1% |
| intelephense | ~40MB | 6.9MB | ~1% |
| Total (all enabled) | ~480MB | ~11MB | ~7% |

Per-Session Overhead

• Working directory tested: ~/.claude (config files, no source code)
• Expected LSPs: 0 (no matching extensions)
• Actual LSPs: 6 (all enabled plugins)
• Wasted resources: ~480MB RAM + 6 idle processes per session

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Related Issues

• #22344 - Subagent system prompt bloat
• #22345 - Plugin skills lack granular control
• #13605 - Custom plugin subagents cannot access MCP tools