feat(input_window): add shell command execution support

- enable executing shell commands prefixed with '!' in input window
- display command output in a dedicated output window
- prompt user to append command and output to input context
- handle command execution errors and notify user on failure
- touches(ui): update input window interactions and context management

Author: aweis89

lua/opencode/core.lua

@@ -93,7 +93,6 @@ M.open = Promise.async(function(opts)
     if opts.new_session then
       state.active_session = nil
       state.last_sent_context = nil
-      context.unload_attachments()
 
       state.current_model = nil
       state.current_mode = nil

lua/opencode/ui/completion/context.lua

@@ -114,7 +114,7 @@ local function add_mentioned_files_items(ctx)
           true,
           'Select to remove file ' .. filename,
           icons.get('file'),
-          nil,
+          { file_path = file },
           kind_priority.mentioned_file
         )
       )
@@ -277,8 +277,8 @@ local context_source = {
     state.current_context_config = context_cfg
 
     if type == 'mentioned_file' then
-      context.remove_file(item.data.name)
-      input_win.remove_mention(item.data.name)
+      local file_path = item.data.additional_data and item.data.additional_data.file_path or item.data.name
+      context.remove_file(file_path)
     elseif type == 'subagent' then
       local subagent_name = item.data.name:gsub(' %(agent%)$', '')
       context.remove_subagent(subagent_name)

lua/opencode/ui/input_window.lua

@@ -66,6 +66,11 @@ function M.handle_submit()
     return
   end
 
+  if input_content:match('^!') then
+    M._execute_shell_command(input_content:sub(2))
+    return
+  end
+
   local key = config.get_key_for_function('input_window', 'slash_commands') or '/'
   if input_content:match('^' .. key) then
     M._execute_slash_command(input_content)
@@ -75,6 +80,76 @@ function M.handle_submit()
   require('opencode.core').send_message(input_content)
 end
 
+M._execute_shell_command = function(command)
+  local cmd = command:match('^%s*(.-)%s*$')
+  if cmd == '' then
+    return
+  end
+
+  local shell = vim.o.shell
+  local shell_cmd = { shell, '-c', cmd }
+
+  vim.system(shell_cmd, { text = true }, function(result)
+    vim.schedule(function()
+      if result.code ~= 0 then
+        vim.notify('Command failed with exit code ' .. result.code, vim.log.levels.ERROR)
+      end
+
+      local output = result.stdout or ''
+      if result.stderr and result.stderr ~= '' then
+        output = output .. '\n' .. result.stderr
+      end
+
+      M._prompt_add_to_context(cmd, output, result.code)
+    end)
+  end)
+end
+
+M._prompt_add_to_context = function(cmd, output, exit_code)
+  local output_window = require('opencode.ui.output_window')
+  if not output_window.mounted() then
+    return
+  end
+
+  local formatted_output = string.format('$ %s\n%s', cmd, output)
+  local lines = vim.split(formatted_output, '\n')
+
+  output_window.set_lines(lines)
+
+  vim.ui.select({ 'Yes', 'No' }, {
+    prompt = 'Add command + output to context?',
+  }, function(choice)
+    if choice == 'Yes' then
+      local message = string.format('Command: `%s`\nExit code: %d\nOutput:\n```\n%s```', cmd, exit_code, output)
+      M._append_to_input(message)
+      output_window.clear()
+    end
+    require('opencode.ui.input_window').focus_input()
+  end)
+end
+
+M._append_to_input = function(text)
+  if not M.mounted() then
+    return
+  end
+
+  local current_lines = vim.api.nvim_buf_get_lines(state.windows.input_buf, 0, -1, false)
+  local new_lines = vim.split(text, '\n')
+
+  if #current_lines == 1 and current_lines[1] == '' then
+    vim.api.nvim_buf_set_lines(state.windows.input_buf, 0, -1, false, new_lines)
+  else
+    vim.api.nvim_buf_set_lines(state.windows.input_buf, -1, -1, false, { '', '---', '' })
+    vim.api.nvim_buf_set_lines(state.windows.input_buf, -1, -1, false, new_lines)
+  end
+
+  M.refresh_placeholder(state.windows)
+  require('opencode.ui.mention').highlight_all_mentions(state.windows.input_buf)
+
+  local line_count = vim.api.nvim_buf_line_count(state.windows.input_buf)
+  vim.api.nvim_win_set_cursor(state.windows.input_win, { line_count, 0 })
+end
+
 M._execute_slash_command = function(command)
   local slash_commands = require('opencode.api').get_slash_commands():await()
   local key = config.get_key_for_function('input_window', 'slash_commands') or '/'
@@ -160,6 +235,8 @@ function M.refresh_placeholder(windows, input_lines)
     vim.api.nvim_buf_set_extmark(windows.input_buf, ns_id, 0, 0, {
       virt_text = {
         { 'Type your prompt here... ', 'OpencodeHint' },
+        { '!', 'OpencodeInputLegend' },
+        { ' shell ', 'OpencodeHint' },
         { slash_key or '/', 'OpencodeInputLegend' },
         { ' commands ', 'OpencodeHint' },
         { mention_key or '@', 'OpencodeInputLegend' },

tests/unit/context_completion_spec.lua

@@ -314,19 +314,12 @@ describe('context completion', function()
 
     it('should remove mentioned file when selected', function()
       local remove_file_called = false
-      local remove_mention_called = false
 
       local context_module = require('opencode.context')
-      local input_win_module = require('opencode.ui.input_window')
 
       context_module.remove_file = function(name)
         remove_file_called = true
-        assert.are.equal('test.lua', name)
-      end
-
-      input_win_module.remove_mention = function(name)
-        remove_mention_called = true
-        assert.are.equal('test.lua', name)
+        assert.are.equal('/test/file.lua', name)
       end
 
       local item = {
@@ -335,13 +328,15 @@ describe('context completion', function()
           type = 'mentioned_file',
           name = 'test.lua',
           available = true,
+          additional_data = {
+            file_path = '/test/file.lua',
+          },
         },
       }
 
       source.on_complete(item)
 
       assert.is_true(remove_file_called)
-      assert.is_true(remove_mention_called)
     end)
 
     it('should remove subagent when selected', function()