feat(context): add inline visual selection insertion

Adds a new command and API to insert the current visual selection as a
formatted code block directly into the input buffer. This includes a new
`add_visual_selection_inline` function, a corresponding keymap, and a
helper to build the formatted text. Unit tests are provided to ensure
correct formatting and error handling for edge cases.

Author: jugarpeupv

lua/opencode/api.lua

@@ -1085,6 +1085,29 @@ M.add_visual_selection = Promise.async(
   end
 )
 
+M.add_visual_selection_inline = Promise.async(
+  ---@param opts? {open_input?: boolean}
+  ---@param range OpencodeSelectionRange
+  function(opts, range)
+    opts = vim.tbl_extend('force', { open_input = true }, opts or {})
+    local context = require('opencode.context')
+    local text = context.build_inline_selection_text(range)
+
+    if not text then
+      return
+    end
+
+    M.open_input():await()
+    local input_window = require('opencode.ui.input_window')
+    input_window._append_to_input(text)
+    vim.schedule(function()
+      if vim.fn.mode() ~= 'n' then
+        vim.api.nvim_feedkeys(vim.api.nvim_replace_termcodes('<Esc>', true, false, true), 'n', false)
+      end
+    end)
+  end
+)
+
 ---@type table<string, OpencodeUICommand>
 M.commands = {
   open = {
@@ -1453,6 +1476,11 @@ M.commands = {
     desc = 'Add current visual selection to context',
     fn = M.add_visual_selection,
   },
+
+  add_visual_selection_inline = {
+    desc = 'Insert visual selection as inline code block in the input buffer',
+    fn = M.add_visual_selection_inline,
+  },
 }
 
 M.slash_commands_map = {

lua/opencode/config.lua

@@ -40,6 +40,7 @@ M.defaults = {
       ['<leader>op'] =  { 'configure_provider',                                desc = 'Configure provider' },
       ['<leader>oV'] =  { 'configure_variant',                                 desc = 'Configure model variant' },
       ['<leader>oy'] =  { 'add_visual_selection',         mode = { 'v' },      desc = 'Add visual selection to context' },
+      ['<leader>oY'] =  { 'add_visual_selection_inline',  mode = { 'v' },      desc = 'Insert visual selection inline into input' },
       ['<leader>oz'] =  { 'toggle_zoom',                                       desc = 'Toggle zoom' },
       ['<leader>ov'] =  { 'paste_image',                                       desc = 'Paste image from clipboard' },
       ['<leader>od'] =  { 'diff_open',                                         desc = 'Open diff view' },

lua/opencode/context.lua

@@ -165,6 +165,48 @@ function M.add_visual_selection(range)
   return true
 end
 
+--- Captures the current visual selection and returns the text to be inserted inline
+--- into the opencode input buffer, in the form:
+---
+---   Here is some code from <file-path>:
+---
+---   ```<filetype>
+---   <selected text>
+---   ```
+---
+---@param range? OpencodeSelectionRange
+---@return string|nil text The formatted text to insert, or nil on failure
+function M.build_inline_selection_text(range)
+  local buf = vim.api.nvim_get_current_buf()
+
+  if not util.is_buf_a_file(buf) then
+    vim.notify('Cannot add selection: not a file buffer', vim.log.levels.WARN)
+    return nil
+  end
+
+  local current_selection = BaseContext.get_current_selection(nil, range)
+  if not current_selection then
+    vim.notify('No visual selection found', vim.log.levels.WARN)
+    return nil
+  end
+
+  local file = BaseContext.get_current_file_for_selection(buf)
+  if not file then
+    vim.notify('Cannot determine file for selection', vim.log.levels.WARN)
+    return nil
+  end
+
+  local filetype = vim.bo[buf].filetype or ''
+  local text = string.format(
+    'Here is some code from %s:\n\n```%s\n%s\n```',
+    file.path,
+    filetype,
+    current_selection.text
+  )
+
+  return text
+end
+
 function M.add_file(file)
   local is_file = vim.fn.filereadable(file) == 1
   local is_dir = vim.fn.isdirectory(file) == 1

tests/unit/context_spec.lua

@@ -1140,3 +1140,158 @@ describe('add_visual_selection API', function()
     vim.notify = original_notify
   end)
 end)
+
+describe('build_inline_selection_text', function()
+  local context
+  local BaseContext
+  local util
+
+  before_each(function()
+    context = require('opencode.context')
+    BaseContext = require('opencode.context.base_context')
+    util = require('opencode.util')
+  end)
+
+  it('should return formatted inline text for a visual selection', function()
+    local original_is_buf_a_file = util.is_buf_a_file
+    local original_get_current_selection = BaseContext.get_current_selection
+    local original_get_current_file_for_selection = BaseContext.get_current_file_for_selection
+    local original_get_current_buf = vim.api.nvim_get_current_buf
+
+    util.is_buf_a_file = function()
+      return true
+    end
+    BaseContext.get_current_selection = function()
+      return { text = 'function foo()\n  return 42\nend', lines = '10, 12' }
+    end
+    BaseContext.get_current_file_for_selection = function()
+      return { path = '/tmp/test.lua', name = 'test.lua', extension = 'lua' }
+    end
+    vim.api.nvim_get_current_buf = function()
+      return 5
+    end
+
+    -- Mock vim.bo to return a filetype
+    local original_bo = vim.bo
+    vim.bo = setmetatable({}, {
+      __index = function(_, buf)
+        return { filetype = 'lua' }
+      end,
+    })
+
+    local text = context.build_inline_selection_text()
+
+    assert.is_not_nil(text)
+    assert.is_not_nil(text:match('Here is some code from /tmp/test%.lua:'))
+    assert.is_not_nil(text:match('```lua'))
+    assert.is_not_nil(text:match('function foo%(%)'))
+    assert.is_not_nil(text:match('```$'))
+
+    util.is_buf_a_file = original_is_buf_a_file
+    BaseContext.get_current_selection = original_get_current_selection
+    BaseContext.get_current_file_for_selection = original_get_current_file_for_selection
+    vim.api.nvim_get_current_buf = original_get_current_buf
+    vim.bo = original_bo
+  end)
+
+  it('should return nil and notify when not a file buffer', function()
+    local original_is_buf_a_file = util.is_buf_a_file
+    local original_get_current_buf = vim.api.nvim_get_current_buf
+
+    util.is_buf_a_file = function()
+      return false
+    end
+    vim.api.nvim_get_current_buf = function()
+      return 10
+    end
+
+    local original_notify = vim.notify
+    local notifications = {}
+    vim.notify = function(msg, level)
+      table.insert(notifications, { msg = msg, level = level })
+    end
+
+    local text = context.build_inline_selection_text()
+
+    assert.is_nil(text)
+    assert.equal(1, #notifications)
+    assert.equal('Cannot add selection: not a file buffer', notifications[1].msg)
+    assert.equal(vim.log.levels.WARN, notifications[1].level)
+
+    util.is_buf_a_file = original_is_buf_a_file
+    vim.api.nvim_get_current_buf = original_get_current_buf
+    vim.notify = original_notify
+  end)
+
+  it('should return nil and notify when no visual selection found', function()
+    local original_is_buf_a_file = util.is_buf_a_file
+    local original_get_current_selection = BaseContext.get_current_selection
+    local original_get_current_buf = vim.api.nvim_get_current_buf
+
+    util.is_buf_a_file = function()
+      return true
+    end
+    BaseContext.get_current_selection = function()
+      return nil
+    end
+    vim.api.nvim_get_current_buf = function()
+      return 11
+    end
+
+    local original_notify = vim.notify
+    local notifications = {}
+    vim.notify = function(msg, level)
+      table.insert(notifications, { msg = msg, level = level })
+    end
+
+    local text = context.build_inline_selection_text()
+
+    assert.is_nil(text)
+    assert.equal(1, #notifications)
+    assert.equal('No visual selection found', notifications[1].msg)
+    assert.equal(vim.log.levels.WARN, notifications[1].level)
+
+    util.is_buf_a_file = original_is_buf_a_file
+    BaseContext.get_current_selection = original_get_current_selection
+    vim.api.nvim_get_current_buf = original_get_current_buf
+    vim.notify = original_notify
+  end)
+
+  it('should include the filetype in the code fence', function()
+    local original_is_buf_a_file = util.is_buf_a_file
+    local original_get_current_selection = BaseContext.get_current_selection
+    local original_get_current_file_for_selection = BaseContext.get_current_file_for_selection
+    local original_get_current_buf = vim.api.nvim_get_current_buf
+
+    util.is_buf_a_file = function()
+      return true
+    end
+    BaseContext.get_current_selection = function()
+      return { text = 'const x = 1', lines = '1, 1' }
+    end
+    BaseContext.get_current_file_for_selection = function()
+      return { path = '/tmp/app.ts', name = 'app.ts', extension = 'ts' }
+    end
+    vim.api.nvim_get_current_buf = function()
+      return 6
+    end
+
+    local original_bo = vim.bo
+    vim.bo = setmetatable({}, {
+      __index = function(_, buf)
+        return { filetype = 'typescript' }
+      end,
+    })
+
+    local text = context.build_inline_selection_text()
+
+    assert.is_not_nil(text)
+    assert.is_not_nil(text:match('```typescript'))
+
+    util.is_buf_a_file = original_is_buf_a_file
+    BaseContext.get_current_selection = original_get_current_selection
+    BaseContext.get_current_file_for_selection = original_get_current_file_for_selection
+    vim.api.nvim_get_current_buf = original_get_current_buf
+    vim.bo = original_bo
+  end)
+end)