Ctrl+hover underline ignores LocationLink.originSelectionRange for TextMate-backed file types (whole document underlined)

LSP4IJ version: 0.20.1 (current latest)
IDE: IntelliJ Platform 2024.3 baseline (IntelliJ IDEA CE)
Client plugin setup: a thin LSP client plugin that registers a plain FileType (no com.intellij.lang.Language), TextMate-based highlighting, and maps documents to the server via <fileTypeMapping fileType="..." serverId="..." languageId="..."/>.

What happens

Ctrl/Cmd+hover over an identifier underlines the entire document instead of the identifier. Ctrl/Cmd+click navigation itself lands on the correct target — only the underlined span is wrong.

What the server sends

The client advertises textDocument.definition.linkSupport, and the server answers LocationLink with a precise originSelectionRange (the span the spec designates as "the underlined span for mouse interaction"). Trace from the LSP4IJ console:

[Trace] Sending request 'textDocument/definition - (498)'.
Params: { "textDocument": { "uri": "file:///.../check.pma" },
          "position": { "line": 11, "character": 18 } }

[Trace] Received response 'textDocument/definition - (498)' in 0ms.
Result: [
  {
    "originSelectionRange": { "start": { "line": 11, "character": 16 },
                              "end":   { "line": 11, "character": 20 } },
    "targetUri": "file:///.../check.pma",
    "targetRange":          { "start": { "line": 0, "character": 6 },
                              "end":   { "line": 0, "character": 10 } },
    "targetSelectionRange": { "start": { "line": 0, "character": 6 },
                              "end":   { "line": 0, "character": 10 } }
  }
]

The origin range covers exactly the 4-character identifier under the mouse.

Expected

The Ctrl+hover underline covers originSelectionRange (11:16–11:20 here), not the whole file. For contrast, VS Code's client renders the identical response with a word-precise underline.

Likely mechanism

For a file type backed only by TextMate (no registered Language), the PSI is a single plain-text element, so any element-range fallback degrades to the whole document. Since the LSP response already carries the correct span in originSelectionRange, using it for the underline would fix TextMate/plaintext-backed servers without any client-side lexing.

The server here is pmt lsp from https://github.com/mellonis/machine-toolchains — happy to provide more traces or test builds.

Start at the Ctrl/Cmd-hover definition-navigation path for LocationLink handling, then inspect how originSelectionRange is chosen for plain FileType/TextMate documents. Reproduce with the pmt lsp setup and verify that the underline uses the four-character range in the supplied trace rather than the whole document.