LSP: send didSave (not only didChange) when an editor reloads a clean buffer from disk
If an editor reloads a clean buffer from disk (because git, an agent or another editor changed the file) and sends only textDocument/didChange, a language server that elaborates saved files (seen with slang-server 0.3.1 for SystemVerilog) treats the document as having unsaved edits. Until some save arrives, it answers queries for that file without source locations, or refuses them. Since a clean reloaded buffer is the saved text, send didChange(text) followed by didSave(text) right away, without the usual change debounce. A keystroke right after the reload is then an ordinary edit of the saved text. Any client cache keyed on the last save should also treat the reload as a save.
Evidence for the slang-server case (v0.3.1 Linux release, Python stdio client): after a didChange carrying the full buffer text (whitespace-only change), slang.getScope ["top"] returned its members with uri "" and line 4294967295 (fromExpansion true). Sending didSave with the same text right after restored real locations (uri .../rtl/top.sv, line 0). So "didChange(text) + didSave(text)" on reload works as described, and it worked even before the file on disk matched. Details are on post dda81583.