LSP server sends no per-file diagnostics to clients without pull diagnostics support

[christianvuerings]

Problem

The LSP server only serves per-file diagnostics through pull diagnostics (textDocument/diagnostic); push (textDocument/publishDiagnostics) is only used for config file errors. Clients that do not implement pull diagnostics never receive file diagnostics at all: no errors appear on open, change, or close.

Affected clients include eglot before Dec 2025, Nova, Claude Code, and other lighter LSP clients. Prior discussion in the typescript-go repo: microsoft/typescript-go#2362. Client-side tracking for Claude Code: anthropics/claude-code#40282.

Proposal

When a client advertises textDocument.publishDiagnostics but not textDocument.diagnostic, push per-file diagnostics for open files: publish on open, debounced republish on change, clear on close. Triggers that would send workspace/diagnostic/refresh (watched file changes, config changes, ATA updates) recompute server-side instead, since push-only clients cannot re-pull. Pull-capable clients are unaffected, and the existing disablePushDiagnostics initialization option also disables the new path.

Implemented in #63921 (carried over from microsoft/typescript-go#4297 after the repository move).

[el-pendeloco]

I think this might affect the helix editor (25.07.1) as well. I tested the configuration with tsc's lsp this week and couldn't make the diagnostics work. I could clearly see the interaction between the editor and the lsp in the logs, but the only diagnostics I saw coming in were the tsconfig ones (no errors).

[KiYugadgeter]

It also affect to vim-lsp too.

[stefnotch]

vim-lsp supports pull diagnostics now
prabirshrestha/vim-lsp#1674

Helix seems to also support pull diagnostics helix-editor/helix#11315
However, no new version of Helix has officially been released for quite a while now.