plumb: Skill for Claude Code

Adding an LSP adapter to plumb

An adapter embeds *base.Adapter (internal/lsp/adapters/base), which supplies all 23 lsp.Client methods, and shadows only what its server does differently. rust is the minimal worked example (46 lines); full guide in docs/adding-an-lsp.md.

The 5 steps

1. Create internal/lsp/adapters/<name>/ with a doc.go stating the adapter's validation status (Experimental or Validated — see the promotion rule below).
2. Write adapter.go: type Adapter struct{ *base.Adapter }, var _ lsp.Client = (*Adapter)(nil), func New(conn jsonrpc.Caller) *Adapter { return &Adapter{Adapter: base.New(conn, "<binary-name>")} }, and DefaultInitParams — the one genuinely per-server function. Do NOT hand-write the 23 methods.
3. Shadow only the methods your server does differently, calling through with a.Adapter.X(ctx, params). Escape hatches are package-level FUNCTIONS — base.Call[T], base.CallPtr[T], base.CallRaw, base.Notify, base.Wrap. Never add an exported method to base.Adapter: Go promotes it into all nine adapters and internal/cli resolves optional capabilities structurally, so one stray method silently opts every server into a capability it does not have. An adapter-only capability (e.g. pull diagnostics) is declared in the adapter's own package.
4. base.New installs BOTH transport handlers (notification fan-out + server-request handler); dispatch and handleServerRequest are unexported, so there is nothing to register and nothing to forget. Server-specific work left to you: init options, workspace model, and — for a server that answers only for open documents — a base.OpenTracker held as a NAMED field (never embedded) with an Ensure call in each affected method and a Refresh in DidChangeWatchedFiles. The set of methods needing it differs per server; do not copy another adapter's.
5. Test: unit tests with internal/lsp/jsonrpc/mock.go covering what this adapter adds (not the inherited base); conformance.RunConformance for the protocol contract; and conformance.RunErrorContract for the "<server> <label>: <cause>" strings. Lazy-open adapters also call conformance.RunLazyOpenErrorContract.