diff --git a/AGENTS.md b/AGENTS.md
index 88751a37..c3df645d 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -3,10 +3,12 @@
 ## Build, Lint, and Test
 
 - **Run all tests:** `./run_tests.sh`
-- **Minimal tests:**
+- **Minimal tests:** `./run_tests.sh -t minimal`
   `nvim --headless -u tests/minimal/init.lua -c "lua require('plenary.test_harness').test_directory('./tests/minimal', {minimal_init = './tests/minimal/init.lua', sequential = true})"`
-- **Unit tests:**
+- **Unit tests:** `./run_tests.sh -t unit`
   `nvim --headless -u tests/minimal/init.lua -c "lua require('plenary.test_harness').test_directory('./tests/unit', {minimal_init = './tests/minimal/init.lua'})"`
+- **Replay tests:** `./run_tests.sh -t replay`
+  `nvim --headless -u tests/minimal/init.lua -c "lua require('plenary.test_harness').test_directory('./tests/replay', {minimal_init = './tests/minimal/init.lua'})"`
 - **Run a single test:** Replace the directory in the above command with the test file path, e.g.:
   `nvim --headless -u tests/manual/init.lua -c "lua require('plenary.test_harness').test_directory('./tests/unit/job_spec.lua', {minimal_init = './tests/minimal/init.lua'})"`
 - **Manual/Visual tests:** `./tests/manual/run_replay.sh` - Replay captured event data for visual testing
@@ -27,6 +29,6 @@
 - **Comments:** Only when necessary for clarity. Prefer self-explanatory code.
 - **Functions:** Prefer local functions. Use `M.func` for module exports.
 - **Config:** Centralize in `config.lua`. Use deep merge for user overrides.
-- **Tests:** Place in `tests/minimal/` or `tests/unit/`. Manual/visual tests in `tests/manual/`.
+- **Tests:** Place in `tests/minimal/`, `tests/unit/`, or `tests/replay/`. Manual/visual tests in `tests/manual/`.
 
 _Agentic coding agents must follow these conventions strictly for consistency and reliability._
diff --git a/README.md b/README.md
index 33f366a1..6941e753 100644
--- a/README.md
+++ b/README.md
@@ -110,6 +110,7 @@ require('opencode').setup({
       ['<leader>oq'] = { 'close' }, -- Close UI windows
       ['<leader>os'] = { 'select_session' }, -- Select and load a opencode session
       ['<leader>op'] = { 'configure_provider' }, -- Quick provider and model switch from predefined list
+      ['<leader>oz'] = { 'toggle_zoom' }, -- Zoom in/out on the Opencode windows
       ['<leader>od'] = { 'diff_open' }, -- Opens a diff tab of a modified file since the last opencode prompt
       ['<leader>o]'] = { 'diff_next' }, -- Navigate to next file diff
       ['<leader>o['] = { 'diff_prev' }, -- Navigate to previous file diff
@@ -170,6 +171,7 @@ require('opencode').setup({
     position = 'right', -- 'right' (default) or 'left'. Position of the UI split
     input_position = 'bottom', -- 'bottom' (default) or 'top'. Position of the input window
     window_width = 0.40, -- Width as percentage of editor width
+    zoom_width = 0.8, -- Zoom width as percentage of editor width
     input_height = 0.15, -- Input height as percentage of window height
     display_model = true, -- Display model name on top winbar
     display_context_size = true, -- Display context size in the footer
diff --git a/lua/opencode/api.lua b/lua/opencode/api.lua
index 8268edb3..0e5b3441 100644
--- a/lua/opencode/api.lua
+++ b/lua/opencode/api.lua
@@ -16,6 +16,10 @@ function M.swap_position()
   require('opencode.ui.ui').swap_position()
 end
 
+function M.toggle_zoom()
+  require('opencode.ui.ui').toggle_zoom()
+end
+
 function M.open_input()
   core.open({ new_session = false, focus = 'input', start_insert = true })
 end
@@ -898,6 +902,11 @@ M.commands = {
     fn = M.toggle_pane,
   },
 
+  toggle_zoom = {
+    desc = 'Toggle window zoom',
+    fn = M.toggle_zoom,
+  },
+
   swap = {
     desc = 'Swap pane position left/right',
     fn = M.swap_position,
diff --git a/lua/opencode/config.lua b/lua/opencode/config.lua
index 5694cf4f..4b5c8c8a 100644
--- a/lua/opencode/config.lua
+++ b/lua/opencode/config.lua
@@ -23,6 +23,7 @@ M.defaults = {
       ['<leader>oq'] = { 'close', desc = 'Close Opencode window' },
       ['<leader>os'] = { 'select_session', desc = 'Select session' },
       ['<leader>op'] = { 'configure_provider', desc = 'Configure provider' },
+      ['<leader>oz'] = { 'toggle_zoom', desc = 'Toggle zoom' },
       ['<leader>od'] = { 'diff_open', desc = 'Open diff view' },
       ['<leader>o]'] = { 'diff_next', desc = 'Next diff' },
       ['<leader>o['] = { 'diff_prev', desc = 'Previous diff' },
@@ -86,6 +87,7 @@ M.defaults = {
     position = 'right',
     input_position = 'bottom',
     window_width = 0.40,
+    zoom_width = 0.8,
     input_height = 0.15,
     picker_width = 100,
     display_model = true,
diff --git a/lua/opencode/state.lua b/lua/opencode/state.lua
index 36730b54..2263f5cc 100644
--- a/lua/opencode/state.lua
+++ b/lua/opencode/state.lua
@@ -35,6 +35,7 @@
 ---@field opencode_server OpencodeServer|nil
 ---@field api_client OpencodeApiClient
 ---@field event_manager EventManager|nil
+---@field pre_zoom_width integer|nil
 ---@field required_version string
 ---@field opencode_cli_version string|nil
 ---@field append fun( key:string, value:any)
@@ -60,6 +61,7 @@ local _state = {
   display_route = nil,
   current_mode = nil,
   last_output = 0,
+  pre_zoom_width = nil,
   -- context
   last_sent_context = nil,
   current_context_config = {},
diff --git a/lua/opencode/ui/ui.lua b/lua/opencode/ui/ui.lua
index 29432457..61b1ba96 100644
--- a/lua/opencode/ui/ui.lua
+++ b/lua/opencode/ui/ui.lua
@@ -1,4 +1,3 @@
-local M = {}
 local config = require('opencode.config')
 local state = require('opencode.state')
 local renderer = require('opencode.ui.renderer')
@@ -7,6 +6,8 @@ local input_window = require('opencode.ui.input_window')
 local footer = require('opencode.ui.footer')
 local topbar = require('opencode.ui.topbar')
 
+local M = {}
+
 ---@param windows OpencodeWindowState?
 function M.close_windows(windows)
   if not windows then
@@ -244,4 +245,24 @@ function M.swap_position()
   end)
 end
 
+function M.toggle_zoom()
+  local windows = state.windows
+  if not windows or not state.windows.output_win or not state.windows.input_win then
+    return
+  end
+
+  local width
+
+  if state.pre_zoom_width then
+    width = state.pre_zoom_width
+    state.pre_zoom_width = nil
+  else
+    state.pre_zoom_width = vim.api.nvim_win_get_width(windows.output_win)
+    width = math.floor(config.ui.zoom_width * vim.o.columns)
+  end
+
+  vim.api.nvim_win_set_config(windows.input_win, { width = width })
+  vim.api.nvim_win_set_config(windows.output_win, { width = width })
+end
+
 return M
diff --git a/run_tests.sh b/run_tests.sh
index 6823b999..e9a86902 100755
--- a/run_tests.sh
+++ b/run_tests.sh
@@ -18,13 +18,14 @@ print_usage() {
     echo "Usage: $0 [OPTIONS]"
     echo "Options:"
     echo "  -f, --filter PATTERN    Filter tests by pattern (matches test descriptions)"
-    echo "  -t, --type TYPE         Test type: all, minimal, unit, or specific file path"
+    echo "  -t, --type TYPE         Test type: all, minimal, unit, replay, or specific file path"
     echo "  -h, --help              Show this help message"
     echo ""
     echo "Examples:"
     echo "  $0                                    # Run all tests"
     echo "  $0 -f \"Timer\"                        # Run tests matching 'Timer'"
     echo "  $0 -t unit                           # Run only unit tests"
+    echo "  $0 -t replay                         # Run only replay tests"
     echo "  $0 -t tests/unit/timer_spec.lua      # Run specific test file"
     echo "  $0 -f \"creates a new timer\" -t unit  # Filter unit tests"
 }
@@ -72,8 +73,10 @@ echo "------------------------------------------------"
 # Run tests based on type
 minimal_status=0
 unit_status=0
+replay_status=0
 minimal_output=""
 unit_output=""
+replay_output=""
 
 if [ "$TEST_TYPE" = "all" ] || [ "$TEST_TYPE" = "minimal" ]; then
     # Run minimal tests
@@ -103,8 +106,22 @@ if [ "$TEST_TYPE" = "all" ] || [ "$TEST_TYPE" = "unit" ]; then
     echo "------------------------------------------------"
 fi
 
+if [ "$TEST_TYPE" = "all" ] || [ "$TEST_TYPE" = "replay" ]; then
+    # Run replay tests
+    replay_output=$(nvim --headless -u tests/minimal/init.lua -c "lua require('plenary.test_harness').test_directory('./tests/replay', {minimal_init = './tests/minimal/init.lua'$FILTER_OPTION})" 2>&1)
+    replay_status=$?
+    clean_output "$replay_output"
+
+    if [ $replay_status -eq 0 ]; then
+        echo -e "${GREEN}✓ Replay tests passed${NC}"
+    else
+        echo -e "${RED}✗ Replay tests failed${NC}"
+    fi
+    echo "------------------------------------------------"
+fi
+
 # Handle specific test file
-if [ "$TEST_TYPE" != "all" ] && [ "$TEST_TYPE" != "minimal" ] && [ "$TEST_TYPE" != "unit" ]; then
+if [ "$TEST_TYPE" != "all" ] && [ "$TEST_TYPE" != "minimal" ] && [ "$TEST_TYPE" != "unit" ] && [ "$TEST_TYPE" != "replay" ]; then
     # Assume it's a specific test file path
     if [ -f "$TEST_TYPE" ]; then
         specific_output=$(nvim --headless -u tests/minimal/init.lua -c "lua require('plenary.test_harness').test_directory('./$TEST_TYPE', {minimal_init = './tests/minimal/init.lua'$FILTER_OPTION})" 2>&1)
@@ -129,9 +146,10 @@ fi
 
 # Check for any failures
 all_output="$minimal_output
-$unit_output"
+$unit_output
+$replay_output"
 
-if [ $minimal_status -ne 0 ] || [ $unit_status -ne 0 ] || echo "$all_output" | grep -q "\[31mFail.*||"; then
+if [ $minimal_status -ne 0 ] || [ $unit_status -ne 0 ] || [ $replay_status -ne 0 ] || echo "$all_output" | grep -q "\[31mFail.*||"; then
     echo -e "\n${RED}======== TEST FAILURES SUMMARY ========${NC}"
 
     # Extract and format failures
diff --git a/tests/unit/renderer_spec.lua b/tests/replay/renderer_spec.lua
similarity index 100%
rename from tests/unit/renderer_spec.lua
rename to tests/replay/renderer_spec.lua
diff --git a/tests/unit/api_spec.lua b/tests/unit/api_spec.lua
index e9ad0f92..6a0d55e6 100644
--- a/tests/unit/api_spec.lua
+++ b/tests/unit/api_spec.lua
@@ -518,4 +518,29 @@ describe('opencode.api', function()
       state.current_model = original_model
     end)
   end)
+
+  describe('toggle_zoom', function()
+    it('calls ui.toggle_zoom when toggle_zoom is called', function()
+      stub(ui, 'toggle_zoom')
+
+      api.toggle_zoom()
+
+      assert.stub(ui.toggle_zoom).was_called()
+    end)
+
+    it('is available in the commands table', function()
+      local cmd = api.commands['toggle_zoom']
+      assert.truthy(cmd, 'toggle_zoom command should exist')
+      assert.equal('Toggle window zoom', cmd.desc)
+      assert.is_function(cmd.fn)
+    end)
+
+    it('routes through command interface', function()
+      stub(ui, 'toggle_zoom')
+
+      api.commands.toggle_zoom.fn({})
+
+      assert.stub(ui.toggle_zoom).was_called()
+    end)
+  end)
 end)