[FEATURE] Decouple LSP diagnostic auto-push from the LSP tool (keep navigation, drop publishDiagnostics)

Summary

Request a way to disable automatic diagnostic reporting from an LSP plugin
while keeping the on-demand LSP tool (goToDefinition, findReferences,
hover, documentSymbol, callHierarchy, etc.).

Motivation

Today the two are bundled: registering an LSP server via a plugin
(lspServers: { command, args, extensionToLanguage }) enables both:

1. on-demand navigation via the LSP tool, and
2. automatic publishDiagnostics pushed into the agent's context after edits.

The LSP tool itself has no diagnostics operation — so diagnostics arrive
only through the automatic push. There is no config field to keep (1) without
(2). The only lever is disabling the whole plugin, which also loses navigation.

The auto-push can flood the context window (and, in large workspaces, is often
stale — see companion issue), while the navigation tools remain valuable.

Requested

A toggle to suppress automatic diagnostic injection while keeping the LSP server

• navigation tools, e.g. one of:

• lspServers.<name>.diagnostics: false, or
• a settings.json key (diagnosticsEnabled: false / lsp.diagnostics: "off"),

or

• an env var.

Granularity (off / errors-only / on-demand-only) would be a bonus.

Not a duplicate of prior (declined) requests

This is deliberately narrower than what was closed before:

• #15101 (CLOSED / not planned) asked to disable LSP entirely — this keeps

the LSP server and all navigation tools, only dropping the diagnostic push.

• #26634 (CLOSED / not planned) asked to filter diagnostics by severity —

this is orthogonal; the ask is to decouple the push channel, not tune it.

• #55019 (OPEN) shows the only current lever is --disallowedTools LSP, which

removes the LSP tool wholesale — the opposite of what's wanted here.

The distinguishing motivation is context-window cost: the auto-push consumes
tokens every edit, while navigation (goToDefinition/findReferences/hover/etc.)
remains valuable and cheap (pull-based, on demand).

Environment

• Plugin: typescript-lsp@claude-plugins-official v1.0.0.