feat(ui): refactor renderer and scrolling

- dialog: add support to extend vertical border to trailing blank via config.extend_border_to_trailing_blank
- renderer: wrap full-session rendering in bulk flush (begin/end) and delegate scroll-to-bottom to scroll module
- output_window: simplify visible-bottom-line calculation to use vim.fn.line('w$')
- ui: guard treesitter language registration with pcall to avoid errors in minimal builds

Author: sudo-tee

lua/opencode/ui/dialog.lua

@@ -261,7 +261,11 @@ function Dialog:format_dialog(output, config)
   local end_line = output:get_line_count()
 
   if config.border_hl then
-    formatter.add_vertical_border(output, start_line + 1, end_line, config.border_hl, -2)
+    local border_end = end_line
+    if config.extend_border_to_trailing_blank then
+      border_end = border_end + 1
+    end
+    formatter.add_vertical_border(output, start_line + 1, border_end, config.border_hl, -2)
   end
 
   output:add_line('')

lua/opencode/ui/output_window.lua

@@ -117,37 +117,8 @@ function M.get_visible_bottom_line(win)
   if not win or not vim.api.nvim_win_is_valid(win) then
     return nil
   end
-
-  local buf = vim.api.nvim_win_get_buf(win)
-  if not buf or not vim.api.nvim_buf_is_valid(buf) then
-    return nil
-  end
-
-  local line_count = vim.api.nvim_buf_line_count(buf)
-  if line_count == 0 then
-    return nil
-  end
-
-  local ok_view, view = pcall(vim.api.nvim_win_call, win, vim.fn.winsaveview)
-  if not ok_view or type(view) ~= 'table' then
-    return nil
-  end
-
-  local topline = math.max(1, view.topline or 1)
-  local remaining_height = vim.api.nvim_win_get_height(win)
-  for line = topline, line_count do
-    local ok_height, result = pcall(vim.api.nvim_win_text_height, win, {
-      start_row = line - 1,
-      end_row = line - 1,
-    })
-    local line_height = ok_height and result and result.all or 1
-    remaining_height = remaining_height - line_height
-    if remaining_height <= 0 then
-      return line
-    end
-  end
-
-  return line_count
+  local ok, line = pcall(vim.fn.line, 'w$', win)
+  return (ok and line and line > 0) and line or nil
 end
 
 ---@param win? integer

lua/opencode/ui/renderer.lua

@@ -6,6 +6,7 @@ local Promise = require('opencode.promise')
 local ctx = require('opencode.ui.renderer.ctx')
 local events = require('opencode.ui.renderer.events')
 local flush = require('opencode.ui.renderer.flush')
+local scroll = require('opencode.ui.renderer.scroll')
 
 local M = {}
 
@@ -123,6 +124,8 @@ function M._render_full_session_data(session_data)
   local revert_index = nil
   local set_mode_from_messages = not state.current_model
 
+  flush.begin_bulk_mode()
+
   for i, msg in ipairs(session_data) do
     if state.active_session.revert and state.active_session.revert.messageID == msg.info.id then
       revert_index = i
@@ -159,6 +162,7 @@ function M._render_full_session_data(session_data)
   end
 
   flush.flush()
+  flush.end_bulk_mode()
 
   if set_mode_from_messages then
     set_model_and_mode_from_messages()
@@ -216,28 +220,8 @@ function M.scroll_to_bottom(force)
     return
   end
 
-  local ok, line_count = pcall(vim.api.nvim_buf_line_count, output_buf)
-  if not ok or line_count == 0 then
-    return
-  end
-
-  local prev_line_count = ctx.prev_line_count
-  ctx.prev_line_count = line_count
-
-  local ok_cursor, cursor = pcall(vim.api.nvim_win_get_cursor, output_win)
-
-  local should_scroll = force
-    or prev_line_count == 0
-    or config.ui.output.always_scroll_to_bottom
-    or (ok_cursor and cursor and cursor[1] >= prev_line_count)
-    or output_window.is_at_bottom(output_win)
-
-  if should_scroll then
-    local last_line = vim.api.nvim_buf_get_lines(output_buf, line_count - 1, line_count, false)[1] or ''
-    vim.api.nvim_win_set_cursor(output_win, { line_count, #last_line })
-    vim.api.nvim_win_call(output_win, function()
-      vim.cmd('normal! zb')
-    end)
+  if force or config.ui.output.always_scroll_to_bottom or output_window.is_at_bottom(output_win) then
+    scroll.scroll_win_to_bottom(output_win, output_buf)
   end
 end
 

lua/opencode/ui/ui.lua

@@ -335,8 +335,14 @@ end
 
 function M.create_windows()
   if config.ui.enable_treesitter_markdown then
-    vim.treesitter.language.register('markdown', 'opencode_output')
-    vim.treesitter.language.register('markdown', 'opencode')
+    local ok, treesitter = pcall(function()
+      return vim.treesitter
+    end)
+
+    if ok and treesitter and treesitter.language and treesitter.language.register then
+      treesitter.language.register('markdown', 'opencode_output')
+      treesitter.language.register('markdown', 'opencode')
+    end
   end
 
   local autocmds = require('opencode.ui.autocmds')