update

LOG.md

@@ -185,6 +185,7 @@ Record every decision here with a short rationale. Append new entries; do not re
 - 2026-10-27: Live validation confirmed Intelephense attaches in `WORKSPACE_TEST` and receives the trusted external `includePaths`. Conform reports prettier, phpcbf, and stylua available; nvim-lint resolves eslint_d, phpcs, and markdownlint.
 - 2026-10-27: Updated `AGENTS.md` status and LSP architecture notes to reflect completed colorscheme work and the current Phase 12 implementation.
 - 2026-10-27: Added Conform's built-in `ruff_format` for Python. Ruff was already Mason-managed for diagnostics; this closes a gap where documentation claimed Python formatting but format-on-save had no Python formatter and disabled LSP fallback.
+- 2026-10-27: Fixed `<C-6>` in netrw when no previous real-file buffer has been recorded. Buffer classification now rejects `nil`, non-numeric, and non-positive buffer identifiers before calling Neovim's buffer API, allowing the mapping to fall back safely.
 
 ## Project-Local Configuration
 

MIGRATION_PLAN.md

@@ -484,6 +484,7 @@ Source of truth for the step-by-step rebuild. Keep this concise and up to date.
 - [ ] Validate Oil.nvim file operations
 - [x] Fix working directory behavior (disabled autochdir, locked Telescope to project root)
 - [x] Make alternate-buffer jumps skip netrw explorer buffers when returning to the last real file
+- [x] Guard alternate-buffer tracking against unset or invalid buffer numbers
 
 ## Phase 12.5 — Language tooling validation
 - [ ] Validate HTML/PHP/JS/Markdown tooling

lua/netrw-config.lua

@@ -2,8 +2,12 @@ local map = vim.keymap.set
 local last_file_buf
 local previous_file_buf
 
+local function is_valid_buffer(buf)
+  return type(buf) == 'number' and buf > 0 and vim.api.nvim_buf_is_valid(buf)
+end
+
 local function is_real_file_buffer(buf)
-  return vim.api.nvim_buf_is_valid(buf)
+  return is_valid_buffer(buf)
     and vim.bo[buf].buflisted
     and vim.bo[buf].buftype == ''
     and vim.bo[buf].filetype ~= 'netrw'
@@ -11,7 +15,7 @@ local function is_real_file_buffer(buf)
 end
 
 local function is_netrw_buffer(buf)
-  if not vim.api.nvim_buf_is_valid(buf) then
+  if not is_valid_buffer(buf) then
     return false
   end