Respect user set default_mode and improve agent management

lua/opencode/api.lua

@@ -357,11 +357,11 @@ function M.initialize()
 end
 
 function M.agent_plan()
-  state.current_mode = 'plan'
+  require('opencode.core').switch_to_mode('plan')
 end
 
 function M.agent_build()
-  state.current_mode = 'build'
+  require('opencode.core').switch_to_mode('build')
 end
 
 function M.select_agent()
@@ -373,7 +373,7 @@ function M.select_agent()
       return
     end
 
-    state.current_mode = selection
+    require('opencode.core').switch_to_mode(selection)
   end)
 end
 
@@ -389,7 +389,7 @@ function M.switch_mode()
   -- Calculate next index, wrapping around if necessary
   local next_index = (current_index % #modes) + 1
 
-  state.current_mode = modes[next_index]
+  require('opencode.core').switch_to_mode(modes[next_index])
 end
 
 function M.with_header(lines, show_welcome)

lua/opencode/config_file.lua

@@ -77,13 +77,23 @@ function M.get_opencode_agents()
   end
   local agents = {}
   for agent, opts in pairs(cfg.agent or {}) do
-    if opts.mode == 'primary' or opts.mode == 'all' then
+    -- Only include agents that are enabled and have the right mode
+    if opts.disable ~= true and (opts.mode == 'primary' or opts.mode == 'all') then
       table.insert(agents, agent)
     end
   end
-  for _, mode in ipairs({ 'build', 'plan' }) do
+
+  -- Sort the agents before prepending the default agents
+  table.sort(agents)
+
+  -- Only add build/plan as fallbacks if they're not explicitly disabled in config
+  for _, mode in ipairs({ 'plan', 'build' }) do
     if not vim.tbl_contains(agents, mode) then
-      table.insert(agents, mode)
+      local mode_config = cfg.agent and cfg.agent[mode]
+      -- Only add if not explicitly disabled or if no config exists (default behavior)
+      if mode_config == nil or (mode_config.disable ~= true) then
+        table.insert(agents, 1, mode)
+      end
     end
   end
   return agents

lua/opencode/core.lua

@@ -45,6 +45,8 @@ function M.open(opts)
     state.opencode_server = server_job.ensure_server() --[[@as OpencodeServer]]
   end
 
+  M.ensure_current_mode()
+
   local are_windows_closed = state.windows == nil
 
   if are_windows_closed then
@@ -254,6 +256,56 @@ local function on_opencode_server()
   state.current_permission = nil
 end
 
+--- Switches the current mode to the specified agent.
+--- @param mode string The agent/mode to switch to
+--- @return boolean success Returns true if the mode was switched successfully, false otherwise
+function M.switch_to_mode(mode)
+  if not mode or mode == '' then
+    vim.notify('Mode cannot be empty', vim.log.levels.ERROR)
+    return false
+  end
+
+  local config_file = require('opencode.config_file')
+  local available_agents = config_file.get_opencode_agents()
+
+  if not vim.tbl_contains(available_agents, mode) then
+    vim.notify(
+      string.format('Invalid mode "%s". Available modes: %s', mode, table.concat(available_agents, ', ')),
+      vim.log.levels.ERROR
+    )
+    return false
+  end
+
+  state.current_mode = mode
+  ui.render_output()
+  return true
+end
+
+--- Ensure the current_mode is set using the config.default_mode or falling back to the first available agent.
+--- @return boolean success Returns true if current_mode is set
+function M.ensure_current_mode()
+  if state.current_mode == nil then
+    local config_file = require('opencode.config_file')
+    local available_agents = config_file.get_opencode_agents()
+
+    if not available_agents or #available_agents == 0 then
+      vim.notify('No available agents found', vim.log.levels.ERROR)
+      return false
+    end
+
+    local default_mode = config.default_mode
+
+    -- Try to use the configured default mode if it's available
+    if default_mode and vim.tbl_contains(available_agents, default_mode) then
+      state.current_mode = default_mode
+    else
+      -- Fallback to first available agent
+      state.current_mode = available_agents[1]
+    end
+  end
+  return true
+end
+
 function M.setup()
   state.subscribe('opencode_server', on_opencode_server)
 

lua/opencode/state.lua

@@ -53,7 +53,7 @@ local _state = {
   last_output_window_position = nil,
   last_code_win_before_opencode = nil,
   display_route = nil,
-  current_mode = config.default_mode,
+  current_mode = nil,
   last_output = 0,
   -- context
   last_sent_context = nil,

lua/opencode/ui/topbar.lua

@@ -26,11 +26,11 @@ local function format_model_info()
 end
 
 local function format_mode_info()
-  return ' ' .. state.current_mode:upper() .. ' '
+  return ' ' .. (state.current_mode or ''):upper() .. ' '
 end
 
 local function get_mode_highlight()
-  local mode = state.current_mode:lower()
+  local mode = (state.current_mode or ''):lower()
   if mode == 'build' then
     return '%#OpencodeAgentBuild#'
   elseif mode == 'plan' then

tests/helpers.lua

@@ -20,6 +20,7 @@ function M.replay_setup()
     return nil
   end
 
+  state.current_mode = 'build' -- default mode for tests
   state.windows = ui.create_windows()
 
   -- we use the event manager to dispatch events

tests/unit/config_file_spec.lua

@@ -64,6 +64,21 @@ describe('config_file.setup', function()
     assert.True(vim.tbl_contains(agents, 'plan'))
   end)
 
+  it('get_opencode_agents respects disabled defaults', function()
+    state.api_client = {
+      get_config = function()
+        return Promise.new():resolve({ agent = { ['custom'] = { mode = 'primary' }, ['build'] = { disable = true }, ['plan'] = { disable = false } } })
+      end,
+      get_current_project = function()
+        return Promise.new():resolve({ id = 'p1' })
+      end,
+    }
+    local agents = config_file.get_opencode_agents()
+    assert.True(vim.tbl_contains(agents, 'custom'))
+    assert.False(vim.tbl_contains(agents, 'build'))
+    assert.True(vim.tbl_contains(agents, 'plan'))
+  end)
+
   it('get_opencode_project returns project', function()
     local project = { id = 'p1', name = 'X' }
     state.api_client = {

tests/unit/core_spec.lua

@@ -21,6 +21,9 @@ local function mock_api_client()
     get_current_project = function()
       return Promise.new():resolve({ id = 'test-project-id' })
     end,
+    get_config = function()
+      return Promise.new():resolve({ model = 'gpt-4' })
+    end,
   }
 end