Install LSPs

Enable the lsp tool for a language by installing its language server — and,
when the server install needs it, the underlying toolchain.

Rules

• Everything here is consent-gated: only act on the user's explicit go-ahead,
  and confirm each toolchain install separately — those are system-level
  changes, not part of whatever task prompted this.
• If the user declines, stop. If they ask not to be offered again, call
  lsp_enable with {"language": "<language>", "action": "dismiss"}.
• Prefer the lsp_enable tool over bash whenever the toolchain already
  exists; reach for bash only for the prerequisites lsp_enable refuses to
  install itself.

Per language

Work the ladder for each language the user wants:

1. Check what is missing. Server binaries: gopls,
   typescript-language-server, pyright-langserver (or
   basedpyright-langserver), rust-analyzer — also look in ~/go/bin and
   ~/.cargo/bin, which the lsp tool searches even when they are off PATH.
   Toolchains: go, npm, rustup.
2. Toolchain present → call lsp_enable with
   {"language": "<go|typescript|python|rust>"} and you are done; it runs the
   right server install and verifies the binary resolves.
3. Toolchain missing → show the user the command you intend to run, get
   their confirmation, run it in bash, then return to step 2.
4. Verify with a real lsp query (documentSymbol on an actual source
   file). The first query per workspace can take up to a minute while the
   server indexes; that is normal.

Toolchain installs (step 3 reference)

Go (for gopls):

brew install go            # macOS
sudo apt-get install -y golang-go   # Debian/Ubuntu; or dnf install golang

Or the official downloads at https://go.dev/dl for anything else.

Node/npm (for typescript-language-server and pyright):

brew install node          # macOS
sudo apt-get install -y nodejs npm  # Debian/Ubuntu

Or nvm (https://github.com/nvm-sh/nvm) when the user prefers per-user installs.

rustup (for rust-analyzer):

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

This is the official rust installer; show the user the command before running
it and follow its printed PATH instructions afterwards.

Notes

• go install drops gopls in ~/go/bin and rustup drops rust-analyzer in
  ~/.cargo/bin. The lsp tool finds both without PATH changes; other tools
  may still want a PATH entry.
• All of this can also happen at install time:
  npx @weave-os/router --pi --lsp go,typescript,python,rust.