[nvdorman]

Summary

• encode toolset membership as [] instead of null for dynamic/ungrouped tools such as MCP tools
• defensively normalize nullable toolsets payloads in the Tools page for compatibility with older servers and cached responses
• add backend JSON and frontend normalization regression tests

Root cause

ToolsetsFor returned a nil Go slice for tools not present in named presets. JSON encoded that as null, while the UI assumed string[] and called item.toolsets.slice(...), causing:

Cannot read properties of null (reading 'slice')

Verification

• make check
• 6 web tests, 0 failures
• TypeScript + Vite production build
• Brave smoke test, 15/15 routes
• installed live bundle contains Array.isArray(toolsets) ? toolsets : []
• live daemon health is 200 after restart