fix: prevent duplicate windows by implementing buffer-to-window binding

This should fix #144

Author: sudo-tee

lua/opencode/ui/autocmds.lua

@@ -81,15 +81,12 @@ function M.setup_resize_handler(windows)
   vim.api.nvim_create_autocmd('VimResized', {
     group = resize_group,
     callback = function()
-      require('opencode.ui.ui').reconcile_windows(windows, 'input')
-      require('opencode.ui.ui').reconcile_windows(windows, 'output')
       require('opencode.ui.topbar').render()
       require('opencode.ui.footer').update_window(windows)
       input_window.update_dimensions(windows)
       output_window.update_dimensions(windows)
     end,
   })
-
   vim.api.nvim_create_autocmd('WinResized', {
     group = resize_group,
     callback = function(args)

lua/opencode/ui/buf_fix_win.lua

@@ -0,0 +1,67 @@
+--- Prevents a buffer from appearing in multiple windows (opposite of 'winfixbuf')
+---
+--- This module solves the problem where buffers can appear in multiple windows
+--- despite having 'winfixbuf' set. The 'winfixbuf' option prevents a window from
+--- changing buffers, but doesn't prevent a buffer from appearing in multiple windows.
+---
+local M = {}
+local buff_to_win_map = {}
+local global_autocmd_setup = false
+
+local function close_duplicates(buf, get_win)
+  local intended = get_win()
+  if not intended or not vim.api.nvim_win_is_valid(intended) then
+    return
+  end
+
+  local wins = vim.fn.win_findbuf(buf)
+  if #wins <= 1 then
+    return
+  end
+
+  for _, win in ipairs(wins) do
+    if win ~= intended and vim.api.nvim_win_is_valid(win) then
+      vim.schedule(function()
+        pcall(vim.api.nvim_win_close, win, true)
+      end)
+    end
+  end
+end
+
+local check_all_buffers = vim.schedule_wrap(function()
+  for buf, get_win in pairs(buff_to_win_map) do
+    if vim.api.nvim_buf_is_valid(buf) then
+      close_duplicates(buf, get_win)
+    else
+      buff_to_win_map[buf] = nil
+    end
+  end
+end)
+
+local function setup()
+  if global_autocmd_setup then
+    return
+  end
+  global_autocmd_setup = true
+
+  vim.api.nvim_create_autocmd({ 'WinNew', 'VimResized' }, {
+    callback = check_all_buffers,
+  })
+end
+
+--- Protect a buffer from appearing in multiple windows
+---@param buf integer Buffer number
+---@param get_intended_window fun(): integer? Function returning intended window ID
+function M.fix_to_win(buf, get_intended_window)
+  setup()
+
+  buff_to_win_map[buf] = get_intended_window
+  vim.api.nvim_create_autocmd('BufWinEnter', {
+    buffer = buf,
+    callback = function()
+      close_duplicates(buf, get_intended_window)
+    end,
+  })
+end
+
+return M

lua/opencode/ui/input_window.lua

@@ -62,6 +62,13 @@ end
 function M.create_buf()
   local input_buf = vim.api.nvim_create_buf(false, true)
   vim.api.nvim_set_option_value('filetype', 'opencode', { buf = input_buf })
+
+  local buffixwin = require('opencode.ui.buf_fix_win')
+  buffixwin.fix_to_win(input_buf, function()
+    local state = require('opencode.state')
+    return state.windows and state.windows.input_win
+  end)
+
   return input_buf
 end
 
@@ -261,6 +268,8 @@ function M.setup(windows)
   set_win_option('number', false, windows)
   set_win_option('relativenumber', false, windows)
   set_buf_option('buftype', 'nofile', windows)
+  set_buf_option('bufhidden', 'hide', windows)
+  set_buf_option('buflisted', false, windows)
   set_buf_option('swapfile', false, windows)
 
   if config.ui.position ~= 'current' then

lua/opencode/ui/output_window.lua

@@ -8,6 +8,13 @@ M.viewport_at_bottom = true
 function M.create_buf()
   local output_buf = vim.api.nvim_create_buf(false, true)
   vim.api.nvim_set_option_value('filetype', 'opencode_output', { buf = output_buf })
+
+  local buffixwin = require('opencode.ui.buf_fix_win')
+  buffixwin.fix_to_win(output_buf, function()
+    local state = require('opencode.state')
+    return state.windows and state.windows.output_win
+  end)
+
   return output_buf
 end
 
@@ -97,7 +104,10 @@ function M.setup(windows)
   set_win_option('relativenumber', false, windows.output_win)
   set_buf_option('modifiable', false, windows.output_buf)
   set_buf_option('buftype', 'nofile', windows.output_buf)
+  set_buf_option('bufhidden', 'hide', windows.output_buf)
+  set_buf_option('buflisted', false, windows.output_buf)
   set_buf_option('swapfile', false, windows.output_buf)
+
   if config.ui.position ~= 'current' then
     set_win_option('winfixbuf', true, windows.output_win)
   end

lua/opencode/ui/ui.lua

@@ -296,48 +296,4 @@ function M.toggle_zoom()
   end
 end
 
----Reconcile window state when duplicate windows may have been created
----This can happen when external commands like 'tabdo' manipulate window layouts
----@param windows OpencodeWindowState?
----@param key string
-function M.reconcile_windows(windows, key)
-  local buf_key = key .. '_buf'
-  if not windows or not windows[buf_key] then
-    return
-  end
-
-  local wins = vim.fn.win_findbuf(windows[buf_key])
-  if type(wins) ~= 'table' or #wins == 0 then
-    return
-  end
-
-  local valid_wins = {}
-  for _, win in ipairs(wins) do
-    if vim.api.nvim_win_is_valid(win) then
-      table.insert(valid_wins, win)
-    end
-  end
-  if #valid_wins == 0 then
-    return
-  end
-
-  local current_tab = vim.api.nvim_get_current_tabpage()
-  local preferred = nil
-  for _, win in ipairs(valid_wins) do
-    if vim.api.nvim_win_get_tabpage(win) == current_tab then
-      preferred = win
-      break
-    end
-  end
-  preferred = preferred or valid_wins[1]
-
-  windows[key .. '_win'] = preferred
-
-  for _, win in ipairs(valid_wins) do
-    if win ~= preferred and vim.api.nvim_win_get_tabpage(win) == current_tab then
-      pcall(vim.api.nvim_win_close, win, false)
-    end
-  end
-end
-
 return M