hide diagnostics in netrw previews

LOG.md

@@ -216,6 +216,7 @@ Record every decision here with a short rationale. Append new entries; do not re
 - 2026-10-28: Automated Phase 14 checks passed for file/directory transitions, manual close and reopen, all four file-open actions, tree expansion and collapse, rapid cursor movement, spaces, Unicode, symlinks, empty and unreadable directories, and the 200-entry cap. A PTY-backed launch on a directory confirmed Neovim 0.12 enters the configured netrw tree, so no special `filetype=directory` handling is required. Separate-tab, deleted-entry, and real SSH checks remain as interactive validation.
 - 2026-10-28: An isolated lifecycle rerun exposed netrw's focus hop into an existing preview window while replacing a directory summary through its native preview function. The extension now explicitly restores the netrw window after that call, preserving tree-focused `j`/`k` navigation. Leave cleanup waits 20 ms before checking the settled current window and ignores callbacks raised while the native preview call is active, then closes only after a real explorer exit. The transient re-entrancy guard is not preview-mode state, and the cleanup timer is released when the netrw buffer is wiped.
 - 2026-10-28: Fixed a reproducible Neovim 0.12 Tree-sitter race during rapid cross-language netrw previews. Native `:pedit` unloads the previous preview buffer while its asynchronous parser may still be running, producing `TSNode:range()` errors. Preview-only file buffers are now kept loaded but unlisted for the rest of the Neovim session, with Tree-sitter highlighting suspended in favor of Vim syntax; avoiding parser detachment is necessary because delayed unloading reproduces the same race. Pre-existing buffer state is preserved, while entering a previewed file for real editing restores listed-buffer behavior and Tree-sitter immediately. An 80-step Markdown/Lua/JSON preview stress test, edit restoration check, retained-buffer check, and pre-existing-buffer check all pass.
+- 2026-10-28: Disabled diagnostic rendering in netrw file preview buffers. The preview metadata records each buffer's prior diagnostic state and restores it when the file is opened for editing, keeping ephemeral previews quiet without overriding buffers where diagnostics were already disabled.
 
 ## Project-Local Configuration
 

MIGRATION_PLAN.md

@@ -667,6 +667,7 @@ file  3.2K     2026-10-27 12:55  telescope.lua
 - [x] Test spaces, Unicode, symlinks, unreadable entries, and large directories
 - [x] Test rapid cursor movement for flicker, stale timers, and excess filesystem work
 - [x] Prevent Tree-sitter parser races during rapid cross-language file preview replacement and restore highlighting on edit
+- [x] Hide diagnostics in file previews and restore their prior per-buffer state on edit
 - [ ] Test the workflow in an actual SSH session
 - [ ] Confirm stock netrw remains understandable when this configuration is unavailable
 

README.md

@@ -113,6 +113,7 @@ entries, and symbolic links are displayed without following them recursively.
 File previews use Vim's syntax highlighting while Tree-sitter is suspended to
 avoid asynchronous parser races during rapid replacement; normal Tree-sitter
 highlighting resumes automatically when a previewed file is opened for editing.
+Diagnostics are hidden in previews and restored to their prior state on edit.
 Preview-only file buffers remain loaded but unlisted until Neovim exits, avoiding
 the parser detachment that triggers this Neovim 0.12 race.
 

lua/netrw-preview.lua

@@ -65,6 +65,7 @@ local function restore_preview_buffer(buf, for_editing)
   vim.bo[buf].bufhidden = metadata.bufhidden
   vim.bo[buf].buflisted = for_editing or metadata.buflisted
   vim.bo[buf].syntax = metadata.syntax
+  vim.diagnostic.enable(metadata.diagnostics_enabled, { bufnr = buf })
   if metadata.treesitter_active then
     pcall(vim.treesitter.start, buf)
   end
@@ -447,6 +448,7 @@ local function show_native_preview(state, entry)
     bufhidden = vim.bo[existing_buf].bufhidden,
     syntax = vim.bo[existing_buf].syntax,
     treesitter_active = vim.treesitter.highlighter.active[existing_buf] ~= nil,
+    diagnostics_enabled = vim.diagnostic.is_enabled({ bufnr = existing_buf }),
   } or nil
 
   local ok, shown = pcall(native_preview, entry)
@@ -466,12 +468,17 @@ local function show_native_preview(state, entry)
             and existing.loaded
             and existing.treesitter_active
           or vim.treesitter.highlighter.active[preview_buf] ~= nil,
+        diagnostics_enabled = existing ~= nil
+            and existing.buf == preview_buf
+            and existing.diagnostics_enabled
+          or vim.diagnostic.is_enabled({ bufnr = preview_buf }),
       }
 
       vim.bo[preview_buf].bufhidden = 'hide'
       vim.bo[preview_buf].buflisted = preview_buffers[preview_buf].buflisted
       vim.b[preview_buf].netrw_live_preview_buffer = true
       pcall(vim.treesitter.stop, preview_buf)
+      vim.diagnostic.enable(false, { bufnr = preview_buf })
 
       local filetype = vim.bo[preview_buf].filetype
       if filetype ~= '' then