fix(ui): preserve zoom state on redraw

lua/opencode/ui/input_window.lua

@@ -50,7 +50,8 @@ local function apply_dimensions(windows, height)
   end
 
   local total_width = vim.api.nvim_get_option_value('columns', {})
-  local width = math.floor(total_width * config.ui.window_width)
+  local width_ratio = state.pre_zoom_width and config.ui.zoom_width or config.ui.window_width
+  local width = math.floor(total_width * width_ratio)
 
   vim.api.nvim_win_set_config(windows.input_win, { width = width, height = height })
 end

lua/opencode/ui/output_window.lua

@@ -115,7 +115,8 @@ function M.update_dimensions(windows)
     return
   end
   local total_width = vim.api.nvim_get_option_value('columns', {})
-  local width = math.floor(total_width * config.ui.window_width)
+  local width_ratio = state.pre_zoom_width and config.ui.zoom_width or config.ui.window_width
+  local width = math.floor(total_width * width_ratio)
 
   vim.api.nvim_win_set_config(windows.output_win, { width = width })
 end

tests/unit/zoom_spec.lua

@@ -0,0 +1,197 @@
+local state = require('opencode.state')
+local config = require('opencode.config')
+local input_window = require('opencode.ui.input_window')
+local output_window = require('opencode.ui.output_window')
+local ui = require('opencode.ui.ui')
+
+describe('ui zoom state', function()
+  local windows
+  local original_columns
+
+  before_each(function()
+    original_columns = vim.o.columns
+    vim.o.columns = 200
+
+    config.setup({
+      ui = {
+        window_width = 0.4,
+        zoom_width = 0.8,
+        position = 'right',
+      },
+    })
+
+    local input_buf = vim.api.nvim_create_buf(false, true)
+    local output_buf = vim.api.nvim_create_buf(false, true)
+    local input_win = vim.api.nvim_open_win(input_buf, true, {
+      relative = 'editor',
+      width = 80,
+      height = 10,
+      row = 0,
+      col = 0,
+    })
+    local output_win = vim.api.nvim_open_win(output_buf, false, {
+      relative = 'editor',
+      width = 80,
+      height = 20,
+      row = 11,
+      col = 0,
+    })
+
+    windows = {
+      input_buf = input_buf,
+      input_win = input_win,
+      output_buf = output_buf,
+      output_win = output_win,
+    }
+    state.windows = windows
+    state.pre_zoom_width = nil
+  end)
+
+  after_each(function()
+    vim.o.columns = original_columns
+    state.pre_zoom_width = nil
+
+    if windows then
+      pcall(vim.api.nvim_win_close, windows.input_win, true)
+      pcall(vim.api.nvim_win_close, windows.output_win, true)
+      pcall(vim.api.nvim_buf_delete, windows.input_buf, { force = true })
+      pcall(vim.api.nvim_buf_delete, windows.output_buf, { force = true })
+    end
+    state.windows = nil
+  end)
+
+  describe('toggle_zoom', function()
+    it('sets zoom width when not zoomed', function()
+      local initial_width = vim.api.nvim_win_get_width(windows.output_win)
+
+      ui.toggle_zoom()
+
+      local expected_zoom_width = math.floor(config.ui.zoom_width * vim.o.columns)
+      local actual_width = vim.api.nvim_win_get_width(windows.output_win)
+
+      assert.is_not_nil(state.pre_zoom_width)
+      assert.equals(initial_width, state.pre_zoom_width)
+      assert.equals(expected_zoom_width, actual_width)
+    end)
+
+    it('restores original width when zoomed', function()
+      local initial_width = vim.api.nvim_win_get_width(windows.output_win)
+
+      ui.toggle_zoom()
+      ui.toggle_zoom()
+
+      local actual_width = vim.api.nvim_win_get_width(windows.output_win)
+
+      assert.is_nil(state.pre_zoom_width)
+      assert.equals(initial_width, actual_width)
+    end)
+
+    it('sets zoom width for both input and output windows', function()
+      ui.toggle_zoom()
+
+      local expected_zoom_width = math.floor(config.ui.zoom_width * vim.o.columns)
+      local input_width = vim.api.nvim_win_get_width(windows.input_win)
+      local output_width = vim.api.nvim_win_get_width(windows.output_win)
+
+      assert.equals(expected_zoom_width, input_width)
+      assert.equals(expected_zoom_width, output_width)
+    end)
+  end)
+
+  describe('input_window.update_dimensions', function()
+    it('uses default window_width when not zoomed', function()
+      input_window.update_dimensions(windows)
+
+      local expected_width = math.floor(config.ui.window_width * vim.o.columns)
+      local actual_width = vim.api.nvim_win_get_width(windows.input_win)
+
+      assert.equals(expected_width, actual_width)
+    end)
+
+    it('uses zoom_width when zoomed', function()
+      state.pre_zoom_width = 80
+
+      input_window.update_dimensions(windows)
+
+      local expected_width = math.floor(config.ui.zoom_width * vim.o.columns)
+      local actual_width = vim.api.nvim_win_get_width(windows.input_win)
+
+      assert.equals(expected_width, actual_width)
+    end)
+
+    it('preserves zoom state after update_dimensions', function()
+      state.pre_zoom_width = 80
+
+      input_window.update_dimensions(windows)
+
+      assert.equals(80, state.pre_zoom_width)
+    end)
+  end)
+
+  describe('output_window.update_dimensions', function()
+    it('uses default window_width when not zoomed', function()
+      output_window.update_dimensions(windows)
+
+      local expected_width = math.floor(config.ui.window_width * vim.o.columns)
+      local actual_width = vim.api.nvim_win_get_width(windows.output_win)
+
+      assert.equals(expected_width, actual_width)
+    end)
+
+    it('uses zoom_width when zoomed', function()
+      state.pre_zoom_width = 80
+
+      output_window.update_dimensions(windows)
+
+      local expected_width = math.floor(config.ui.zoom_width * vim.o.columns)
+      local actual_width = vim.api.nvim_win_get_width(windows.output_win)
+
+      assert.equals(expected_width, actual_width)
+    end)
+
+    it('preserves zoom state after update_dimensions', function()
+      state.pre_zoom_width = 80
+
+      output_window.update_dimensions(windows)
+
+      assert.equals(80, state.pre_zoom_width)
+    end)
+  end)
+
+  describe('zoom state persistence', function()
+    it('maintains zoom width after input window show/hide cycle', function()
+      ui.toggle_zoom()
+
+      local expected_zoom_width = math.floor(config.ui.zoom_width * vim.o.columns)
+
+      input_window.update_dimensions(windows)
+
+      local actual_width = vim.api.nvim_win_get_width(windows.input_win)
+      assert.equals(expected_zoom_width, actual_width)
+      assert.is_not_nil(state.pre_zoom_width)
+    end)
+
+    it('maintains zoom width after output window update_dimensions', function()
+      ui.toggle_zoom()
+
+      local expected_zoom_width = math.floor(config.ui.zoom_width * vim.o.columns)
+
+      output_window.update_dimensions(windows)
+
+      local actual_width = vim.api.nvim_win_get_width(windows.output_win)
+      assert.equals(expected_zoom_width, actual_width)
+      assert.is_not_nil(state.pre_zoom_width)
+    end)
+
+    it('correctly un-zooms after multiple update_dimensions calls', function()
+      ui.toggle_zoom()
+
+      input_window.update_dimensions(windows)
+      output_window.update_dimensions(windows)
+
+      ui.toggle_zoom()
+
+      assert.is_nil(state.pre_zoom_width)
+    end)
+  end)
+end)