feat(opencode): add model variant support and cycle command

Add per-model variant support and UI/commands to select and cycle variants.
- Add lua/opencode/model_state.lua to persist favorites, recent and selected variants
- Add lua/opencode/variant_picker.lua and expose configure_variant / cycle_variant
- Thread variant through API/client, core send flow, config, types, utils and UI footer
- Update model picker, keymaps, highlights and state to load/save the current variant

Enable selecting, remembering, and cycling model variants for the active model.

Author: sudo-tee

README.md

@@ -127,6 +127,7 @@ require('opencode').setup({
       ['<leader>os'] = { 'select_session' }, -- Select and load a opencode session
       ['<leader>oR'] = { 'rename_session' }, -- Rename current session
       ['<leader>op'] = { 'configure_provider' }, -- Quick provider and model switch from predefined list
+      ['<leader>oV'] = { 'configure_variant' }, -- Switch model variant for the current model
       ['<leader>oz'] = { 'toggle_zoom' }, -- Zoom in/out on the Opencode windows
       ['<leader>ov'] = { 'paste_image'}, -- Paste image from clipboard into current session
       ['<leader>od'] = { 'diff_open' }, -- Opens a diff tab of a modified file since the last opencode prompt
@@ -161,6 +162,7 @@ require('opencode').setup({
       ['<up>'] = { 'prev_prompt_history', mode = { 'n', 'i' } }, -- Navigate to previous prompt in history
       ['<down>'] = { 'next_prompt_history', mode = { 'n', 'i' } }, -- Navigate to next prompt in history
       ['<M-m>'] = { 'switch_mode' }, -- Switch between modes (build/plan)
+      ['<M-r>'] = { 'cycle_variant', mode = { 'n', 'i' } }, -- Cycle through available model variants
     },
     output_window = {
       ['<esc>'] = { 'close' }, -- Close UI windows
@@ -169,6 +171,7 @@ require('opencode').setup({
       ['[['] = { 'prev_message' }, -- Navigate to previous message in the conversation
       ['<tab>'] = { 'toggle_pane', mode = { 'n', 'i' } }, -- Toggle between input and output panes
       ['i'] = { 'focus_input', 'n' }, -- Focus on input window and enter insert mode at the end of the input from the output window
+      ['<M-r>'] = { 'cycle_variant', mode = { 'n' } }, -- Cycle through available model variants
       ['<leader>oS'] = { 'select_child_session' }, -- Select and load a child session
       ['<leader>oD'] = { 'debug_message' }, -- Open raw message in new buffer for debugging
       ['<leader>oO'] = { 'debug_output' }, -- Open raw output in new buffer for debugging
@@ -377,6 +380,18 @@ In the model picker, press **`<C-f>`** to toggle the currently selected model as
 
 No configuration is needed - the plugin respects and updates the OpenCode CLI format automatically.
 
+### Model Variants
+
+Some models support multiple variants (e.g., different context window sizes or optimization modes). The plugin provides convenient ways to switch between available variants for the currently active model.
+
+#### Switching Variants
+
+- **Via picker**: Press `<leader>oV` to open the variant picker showing all available variants for the current model
+- **Via cycling**: Press `<M-r>` (Alt+R) in the input or output window to cycle through available variants
+- **Via slash command**: Type `/variant` in the input window
+
+When you switch variants, the plugin remembers your selection per model, so the next time you use that model, it will automatically use the last selected variant.
+
 ### UI icons (disable emojis or customize)
 
 By default, opencode.nvim uses emojis for icons in the UI. If you prefer a plain, emoji-free interface, you can switch to the `text` preset or override icons individually.
@@ -552,6 +567,8 @@ The plugin provides the following actions that can be triggered via keymaps, com
 | Open timeline picker (navigate/undo/redo/fork to message)   | `<leader>oT`                          | `:Opencode timeline`                        | `require('opencode.api').timeline()`                                   |
 | Browse code references from conversation                    | `gr` (window)                         | `:Opencode references` / `/references`      | `require('opencode.api').references()`                                 |
 | Configure provider and model                                | `<leader>op`                          | `:Opencode configure provider`              | `require('opencode.api').configure_provider()`                         |
+| Configure model variant                                     | `<leader>oV`                          | `:Opencode variant` / `/variant`            | `require('opencode.api').configure_variant()`                          |
+| Cycle through model variants                                | `<M-r>` (window)                      | -                                           | `require('opencode.api').cycle_variant()`                              |
 | Open diff view of changes                                   | `<leader>od`                          | `:Opencode diff open`                       | `require('opencode.api').diff_open()`                                  |
 | Navigate to next file diff                                  | `<leader>o]`                          | `:Opencode diff next`                       | `require('opencode.api').diff_next()`                                  |
 | Navigate to previous file diff                              | `<leader>o[`                          | `:Opencode diff prev`                       | `require('opencode.api').diff_prev()`                                  |
@@ -720,6 +737,7 @@ You can run predefined user commands and built-in slash commands from the input
 - `/help` — Show help
 - `/mcp` — Show MCP servers
 - `/models` — Switch provider/model
+- `/variant` — Switch model variant
 - `/sessions` — Switch session
 - `/child-sessions` — Switch to a child session
 - `/agent` — Switch agent/mode

lua/opencode/api.lua

@@ -83,6 +83,14 @@ function M.configure_provider()
   core.configure_provider()
 end
 
+function M.configure_variant()
+  core.configure_variant()
+end
+
+function M.cycle_variant()
+  core.cycle_variant()
+end
+
 function M.cancel()
   core.cancel()
 end
@@ -1205,6 +1213,11 @@ M.commands = {
     fn = M.configure_provider,
   },
 
+  variant = {
+    desc = 'Switch model variant',
+    fn = M.configure_variant,
+  },
+
   run = {
     desc = 'Run prompt in current session',
     fn = function(args)
@@ -1334,6 +1347,7 @@ M.slash_commands_map = {
   ['/history'] = { fn = M.select_history, desc = 'Select from history' },
   ['/mcp'] = { fn = M.mcp, desc = 'Show MCP server configuration' },
   ['/models'] = { fn = M.configure_provider, desc = 'Switch provider/model' },
+  ['/variant'] = { fn = M.configure_variant, desc = 'Switch model variant' },
   ['/new'] = { fn = M.open_input_new_session, desc = 'Create new session' },
   ['/redo'] = { fn = M.redo, desc = 'Redo last action' },
   ['/sessions'] = { fn = M.select_session, desc = 'Select session' },
@@ -1365,6 +1379,7 @@ M.legacy_command_map = {
   OpencodeSelectChildSession = 'session child',
   OpencodeTogglePane = 'toggle_pane',
   OpencodeConfigureProvider = 'models',
+  OpencodeConfigureVariant = 'variant',
   OpencodeRun = 'run',
   OpencodeRunNewSession = 'run_new',
   OpencodeDiff = 'diff open',

lua/opencode/api_client.lua

@@ -235,7 +235,7 @@ end
 
 --- Create and send a new message to a session
 --- @param id string Session ID (required)
---- @param message_data {messageID?: string, model?: {providerID: string, modelID: string}, agent?: string, system?: string, tools?: table<string, boolean>, parts: OpencodeMessagePart[]} Message creation data
+--- @param message_data {messageID?: string, model?: {providerID: string, modelID: string}, agent?: string, variant?: string, system?: string, tools?: table<string, boolean>, parts: OpencodeMessagePart[]} Message creation data
 --- @param directory string|nil Directory path
 --- @return Promise<{info: MessageInfo, parts: OpencodeMessagePart[]}>
 function OpencodeApiClient:create_message(id, message_data, directory)

lua/opencode/config.lua

@@ -26,6 +26,7 @@ M.defaults = {
       ['<leader>os'] = { 'select_session', desc = 'Select session' },
       ['<leader>oR'] = { 'rename_session', desc = 'Rename session' },
       ['<leader>op'] = { 'configure_provider', desc = 'Configure provider' },
+      ['<leader>oV'] = { 'configure_variant', desc = 'Configure model variant' },
       ['<leader>oz'] = { 'toggle_zoom', desc = 'Toggle zoom' },
       ['<leader>ov'] = { 'paste_image', desc = 'Paste image from clipboard' },
       ['<leader>od'] = { 'diff_open', desc = 'Open diff view' },
@@ -55,6 +56,7 @@ M.defaults = {
       ['i'] = { 'focus_input' },
       ['gr'] = { 'references', desc = 'Browse code references' },
       ['<M-i>'] = { 'toggle_input', mode = { 'n' }, desc = 'Toggle input window' },
+      ['<M-r>'] = { 'cycle_variant', mode = { 'n' } },
       ['<leader>oS'] = { 'select_child_session' },
       ['<leader>oD'] = { 'debug_message' },
       ['<leader>oO'] = { 'debug_output' },
@@ -73,6 +75,7 @@ M.defaults = {
       ['<up>'] = { 'prev_prompt_history', mode = { 'n', 'i' } },
       ['<down>'] = { 'next_prompt_history', mode = { 'n', 'i' } },
       ['<M-m>'] = { 'switch_mode', mode = { 'n', 'i' } },
+      ['<M-r>'] = { 'cycle_variant', mode = { 'n', 'i' } },
       ['<M-i>'] = { 'toggle_input', mode = { 'n', 'i' }, desc = 'Toggle input window' },
       ['gr'] = { 'references', desc = 'Browse code references' },
       ['<leader>oS'] = { 'select_child_session' },

lua/opencode/config_file.lua

@@ -63,6 +63,10 @@ function M.get_opencode_providers()
   end)
 end
 
+--- Get model information for a specific provider and model
+--- @param provider string Provider ID
+--- @param model string Model ID
+--- @return OpencodeModel|nil Model information with variants
 M.get_model_info = function(provider, model)
   local providers_response = M.get_opencode_providers():peek()
 

lua/opencode/core.lua

@@ -154,13 +154,18 @@ M.send_message = Promise.async(function(prompt, opts)
   context.load()
   opts.model = opts.model or M.initialize_current_model():await()
   opts.agent = opts.agent or state.current_mode or config.default_mode
-
+  opts.variant = opts.variant or state.current_variant
   local params = {}
 
   if opts.model then
     local provider, model = opts.model:match('^(.-)/(.+)$')
     params.model = { providerID = provider, modelID = model }
     state.current_model = opts.model
+
+    if opts.variant then
+      params.variant = opts.variant
+      state.current_variant = opts.variant
+    end
   end
 
   if opts.agent then
@@ -255,7 +260,7 @@ function M.before_run(opts)
 end
 
 function M.configure_provider()
-  require('opencode.provider').select(function(selection)
+  require('opencode.model_picker').select(function(selection)
     if not selection then
       if state.windows then
         ui.focus_input()
@@ -268,11 +273,101 @@ function M.configure_provider()
     if state.windows then
       ui.focus_input()
     else
-      vim.notify('Changed provider to ' .. selection.display, vim.log.levels.INFO)
+      vim.notify('Changed provider to ' .. model_str, vim.log.levels.INFO)
+    end
+  end)
+end
+
+function M.configure_variant()
+  require('opencode.variant_picker').select(function(selection)
+    if not selection then
+      if state.windows then
+        ui.focus_input()
+      end
+      return
+    end
+
+    state.current_variant = selection.name
+
+    -- Save variant to model state
+    if state.current_model then
+      local provider, model = state.current_model:match('^(.-)/(.+)$')
+      if provider and model then
+        local model_state = require('opencode.model_state')
+        model_state.set_variant(provider, model, selection.name)
+      end
+    end
+
+    if state.windows then
+      ui.focus_input()
+    else
+      vim.notify('Changed variant to ' .. selection.name, vim.log.levels.INFO)
     end
   end)
 end
 
+M.cycle_variant = Promise.async(function()
+  if not state.current_model then
+    vim.notify('No model selected', vim.log.levels.WARN)
+    return
+  end
+
+  local provider, model = state.current_model:match('^(.-)/(.+)$')
+  if not provider or not model then
+    return
+  end
+
+  local config_file = require('opencode.config_file')
+  local model_info = config_file.get_model_info(provider, model)
+
+  if not model_info or not model_info.variants then
+    vim.notify('Current model does not support variants', vim.log.levels.WARN)
+    return
+  end
+
+  local variants = {}
+  for variant_name, _ in pairs(model_info.variants) do
+    table.insert(variants, variant_name)
+  end
+
+  table.sort(variants, function(a, b)
+    local priority = { low = 1, medium = 2, high = 3 }
+    local a_priority = priority[a] or 99
+    local b_priority = priority[b] or 99
+    if a_priority ~= b_priority then
+      return a_priority < b_priority
+    end
+    return a < b
+  end)
+
+  if #variants == 0 then
+    return
+  end
+
+  local total_count = #variants + 1
+
+  local current_index
+  if state.current_variant == nil then
+    current_index = total_count
+  else
+    current_index = util.index_of(variants, state.current_variant) or 0
+  end
+
+  local next_index = (current_index % total_count) + 1
+
+  local next_variant
+  if next_index > #variants then
+    next_variant = nil
+  else
+    next_variant = variants[next_index]
+  end
+
+  state.current_variant = next_variant
+
+  local model_state = require('opencode.model_state')
+  model_state.set_variant(provider, model, next_variant)
+end)
+
 M.cancel = Promise.async(function()
   if state.windows and state.active_session then
     if state.is_running() then
@@ -461,6 +556,23 @@ function M.setup()
   state.subscribe('opencode_server', on_opencode_server)
   state.subscribe('user_message_count', M._on_user_message_count_change)
   state.subscribe('pending_permissions', M._on_current_permission_change)
+  state.subscribe('current_model', function(key, new_val, old_val)
+    if new_val ~= old_val then
+      state.current_variant = nil
+
+      -- Load saved variant for the new model
+      if new_val then
+        local provider, model = new_val:match('^(.-)/(.+)$')
+        if provider and model then
+          local model_state = require('opencode.model_state')
+          local saved_variant = model_state.get_variant(provider, model)
+          if saved_variant then
+            state.current_variant = saved_variant
+          end
+        end
+      end
+    end
+  end)
 
   vim.schedule(function()
     M.opencode_ok()