fix: apply agent-specific defaults to new sessions

lua/opencode/protocols/v1/types.lua

@@ -14,7 +14,7 @@
 ---@field list_sessions_project OpencodeV1LocationTableOperation
 ---@field list_session_status OpencodeV1LocationTableOperation
 ---@field list_sessions_global fun(connection: OpencodeV1Connection, reverse_path_map?: OpencodeV1PathMap): Promise<table[]>
----@field create_session fun(connection: OpencodeV1Connection, location: OpencodeLocation, input?: table, path_map?: OpencodeV1PathMap, reverse_path_map?: OpencodeV1PathMap): Promise<table>
+---@field create_session fun(connection: OpencodeV1Connection, location: OpencodeLocation, input?: table, path_map?: OpencodeV1PathMap, reverse_path_map?: OpencodeV1PathMap, selected?: OpencodeSessionSelection): Promise<table>
 ---@field delete_session fun(connection: OpencodeV1Connection, session_id: string, location: OpencodeLocation, path_map?: OpencodeV1PathMap): Promise<boolean>
 ---@field rename_session fun(connection: OpencodeV1Connection, session_id: string, location: OpencodeLocation, title: string, path_map?: OpencodeV1PathMap, reverse_path_map?: OpencodeV1PathMap): Promise<boolean>
 ---@field get_session fun(connection: OpencodeV1Connection, session_id: string, location: OpencodeLocation, path_map?: OpencodeV1PathMap, reverse_path_map?: OpencodeV1PathMap): Promise<table>

lua/opencode/protocols/v2/operations.lua

@@ -109,14 +109,21 @@ function M.get_current_project(connection, location, path_map, reverse_path_map)
   end)
 end
 
----@param connection OpencodeV2Connection
-function M.get_config(connection, location, path_map, reverse_path_map)
-  return json_request(connection, 'V2 get_config', 'GET', '/api/config', {
-    location = { directory = location_directory(location, path_map) },
-  }):and_then(function(value)
-    return map_paths(require_table('V2 get_config', value), reverse_path_map)
-  end)
-end
+---@type fun(connection: OpencodeV2Connection, location: OpencodeLocation, path_map?: OpencodeV2PathMap, reverse_path_map?: OpencodeV2PathMap): Promise<{model?: string, agent: table<string, {model?: string}>}>
+M.get_config = Promise.async(function(connection, location, path_map, reverse_path_map)
+  local model = M.get_default_model(connection, location, path_map, reverse_path_map):await()
+  local agents = M.list_agents(connection, location, path_map, reverse_path_map):await()
+  local config = { agent = {} }
+  if model then
+    config.model = model.providerID .. '/' .. model.id
+  end
+  for _, agent in ipairs(agents) do
+    config.agent[agent.id] = {
+      model = agent.model and (agent.model.providerID .. '/' .. agent.model.id),
+    }
+  end
+  return config
+end)
 
 ---@param connection OpencodeV2Connection
 function M.list_providers(connection, location, path_map, reverse_path_map)
@@ -224,8 +231,21 @@ function M.list_inbox(connection, session_id, reverse_path_map)
 end
 
 ---@param connection OpencodeV2Connection
-function M.create_session(connection, location, input, path_map, reverse_path_map)
+---@param selected? OpencodeSessionSelection
+function M.create_session(connection, location, input, path_map, reverse_path_map, selected)
   local body = map_paths(type(input) == 'table' and vim.deepcopy(input) or {}, path_map)
+  if selected then
+    if body.agent == nil then
+      body.agent = selected.mode
+    end
+    if body.model == nil and body.agent == selected.mode and selected.model then
+      local provider, model = selected.model:match('^(.-)/(.+)$')
+      if not provider or not model then
+        error('V2 create_session model must use provider/model format')
+      end
+      body.model = { providerID = provider, id = model, variant = selected.variant }
+    end
+  end
   body.location = { directory = location_directory(location, path_map) }
   return json_request(connection, 'V2 create_session', 'POST', '/api/session', nil, body):and_then(function(value)
     local session = unwrap_data('V2 create_session', value, reverse_path_map)
@@ -650,6 +670,9 @@ function M.get_default_model(connection, location, path_map, reverse_path_map)
   return json_request(connection, 'V2 get_default_model', 'GET', '/api/model/default', {
     location = { directory = location_directory(location, path_map) },
   }):and_then(function(value)
+    if value.data == vim.NIL then
+      return nil
+    end
     return unwrap_data('V2 get_default_model', value, reverse_path_map)
   end)
 end
@@ -843,7 +866,6 @@ end
 M.contract = {
   { 'GET', '/api/agent' },
   { 'GET', '/api/command' },
-  { 'GET', '/api/config' },
   { 'GET', '/api/form' },
   { 'GET', '/api/fs/find' },
   { 'GET', '/api/location' },

lua/opencode/protocols/v2/types.lua

@@ -48,14 +48,14 @@
 
 ---@class OpencodeV2Operations
 ---@field get_current_project fun(connection: OpencodeV2Connection, location: OpencodeLocation, path_map?: OpencodeV2PathMap, reverse_path_map?: OpencodeV2PathMap): Promise<table>
----@field get_config fun(connection: OpencodeV2Connection, location: OpencodeLocation, path_map?: OpencodeV2PathMap, reverse_path_map?: OpencodeV2PathMap): Promise<table>
+---@field get_config fun(connection: OpencodeV2Connection, location: OpencodeLocation, path_map?: OpencodeV2PathMap, reverse_path_map?: OpencodeV2PathMap): Promise<{model?: string, agent: table<string, {model?: string}>}>
 ---@field list_providers fun(connection: OpencodeV2Connection, location: OpencodeLocation, path_map?: OpencodeV2PathMap, reverse_path_map?: OpencodeV2PathMap): Promise<{location: OpencodeLocation, data: table[]}>
 ---@field list_sessions fun(connection: OpencodeV2Connection, location?: OpencodeLocation, cursor?: string, limit?: integer, path_map?: OpencodeV2PathMap, reverse_path_map?: OpencodeV2PathMap): Promise<OpencodeV2Page<table>>
 ---@field list_sessions_project fun(connection: OpencodeV2Connection, location: OpencodeLocation, path_map?: OpencodeV2PathMap, reverse_path_map?: OpencodeV2PathMap): Promise<table[]>
 ---@field list_sessions_global fun(connection: OpencodeV2Connection, reverse_path_map?: OpencodeV2PathMap): Promise<table[]>
 ---@field list_active_sessions fun(connection: OpencodeV2Connection): Promise<table<string, {type: 'running'}>>
 ---@field list_inbox fun(connection: OpencodeV2Connection, session_id: string, reverse_path_map?: OpencodeV2PathMap): Promise<table[]>
----@field create_session fun(connection: OpencodeV2Connection, location: OpencodeLocation, input?: table, path_map?: OpencodeV2PathMap, reverse_path_map?: OpencodeV2PathMap): Promise<table>
+---@field create_session fun(connection: OpencodeV2Connection, location: OpencodeLocation, input?: table, path_map?: OpencodeV2PathMap, reverse_path_map?: OpencodeV2PathMap, selected?: OpencodeSessionSelection): Promise<table>
 ---@field get_session fun(connection: OpencodeV2Connection, session_id: string, location?: OpencodeLocation, path_map?: OpencodeV2PathMap, reverse_path_map?: OpencodeV2PathMap): Promise<table>
 ---@field delete_session fun(connection: OpencodeV2Connection, session_id: string): Promise<boolean>
 ---@field rename_session fun(connection: OpencodeV2Connection, session_id: string, location: OpencodeLocation?, title: string): Promise<boolean>
@@ -81,7 +81,7 @@
 ---@field cancel_question fun(connection: OpencodeV2Connection, session_id: string, request_id: string): Promise<boolean>
 ---@field list_agents OpencodeV2LocationListOperation
 ---@field list_models OpencodeV2LocationListOperation
----@field get_default_model fun(connection: OpencodeV2Connection, location: OpencodeLocation, path_map?: OpencodeV2PathMap, reverse_path_map?: OpencodeV2PathMap): Promise<table>
+---@field get_default_model fun(connection: OpencodeV2Connection, location: OpencodeLocation, path_map?: OpencodeV2PathMap, reverse_path_map?: OpencodeV2PathMap): Promise<OpencodeV2ModelReference|nil>
 ---@field get_model_catalog fun(connection: OpencodeV2Connection, location: OpencodeLocation, path_map?: OpencodeV2PathMap, reverse_path_map?: OpencodeV2PathMap): Promise<table>
 ---@field list_primary_agents fun(connection: OpencodeV2Connection, location: OpencodeLocation, path_map?: OpencodeV2PathMap, reverse_path_map?: OpencodeV2PathMap): Promise<string[]>
 ---@field list_subagents fun(connection: OpencodeV2Connection, location: OpencodeLocation, path_map?: OpencodeV2PathMap, reverse_path_map?: OpencodeV2PathMap): Promise<string[]>

lua/opencode/services/agent_model.lua

@@ -231,7 +231,10 @@ M.initialize_current_model = Promise.async(function(opts)
   if not is_current() then
     return
   end
-  if cfg and cfg.model and cfg.model ~= '' then
+  local mode_config = cfg and cfg.agent and cfg.agent[state.current_mode]
+  if mode_config and mode_config.model and mode_config.model ~= '' then
+    state.model.set_model(mode_config.model)
+  elseif cfg and cfg.model and cfg.model ~= '' then
     state.model.set_model(cfg.model)
   else
     local catalog = config_file.get_opencode_providers():await()
@@ -249,6 +252,17 @@ M.initialize_current_model = Promise.async(function(opts)
   return state.current_model
 end)
 
+---Resolve current choices and missing defaults for a new interactive session.
+---Rejects when no primary agent is available or a lookup propagates an error.
+---@type fun(): Promise<OpencodeSessionSelection>
+M.resolve_session_selection = Promise.async(function()
+  if not M.ensure_current_mode():await() then
+    error('Cannot resolve session agent')
+  end
+  M.initialize_current_model():await()
+  return { mode = state.current_mode, model = state.current_model, variant = state.current_variant }
+end)
+
 ---Apply a server-side model selection ({id or modelID, providerID, variant?})
 ---to local state; same-value calls are no-ops.
 ---@param model? table

lua/opencode/services/session_runtime.lua

@@ -435,7 +435,8 @@ M.open = Promise.async(function(opts)
   return Promise.new():resolve('ok')
 end)
 
-local create_session = Promise.async(function(connection, location, title_or_opts)
+---@param selected? OpencodeSessionSelection
+local create_session = Promise.async(function(connection, location, title_or_opts, selected)
   local session_request = {}
 
   if type(title_or_opts) == 'string' then
@@ -445,7 +446,7 @@ local create_session = Promise.async(function(connection, location, title_or_opt
   end
 
   local session_response = connection.operations
-    .create_session(connection, location, session_request, util.apply_path_map, util.apply_reverse_path_map)
+    .create_session(connection, location, session_request, util.apply_path_map, util.apply_reverse_path_map, selected)
     :catch(function(err)
       vim.notify('Error creating new session: ' .. vim.inspect(err), vim.log.levels.ERROR)
     end)
@@ -460,7 +461,8 @@ end)
 ---@return Promise<OpencodeSession|nil>
 M.create_new_session = Promise.async(function(title_or_opts)
   local connection = server_job.ensure_server():await()
-  return create_session(connection, current_location(), title_or_opts):await()
+  local selected = agent_model.resolve_session_selection():await()
+  return create_session(connection, current_location(), title_or_opts, selected):await()
 end)
 
 ---@class OpencodeDetachedSession

lua/opencode/types.lua

@@ -10,6 +10,11 @@
 ---@field code? string|number
 ---@field user_data? any
 
+---@class OpencodeSessionSelection
+---@field mode? string
+---@field model? string
+---@field variant? string
+
 ---@class OpencodeConfigFile
 ---@field theme string
 ---@field autoshare boolean

tests/unit/protocol_v1_operations_spec.lua

@@ -85,7 +85,13 @@ describe('V1 protocol operations', function()
         return operations.list_sessions_global(connection, to_host):wait()
       end,
       create_session = function()
-        return operations.create_session(connection, location, { title = 'New' }, to_server, to_host):wait()
+        return operations
+          .create_session(connection, location, { title = 'New' }, to_server, to_host, {
+            mode = 'build',
+            model = 'provider/model',
+            variant = 'high',
+          })
+          :wait()
       end,
       get_session = function()
         return operations.get_session(connection, 'ses-1', location, to_server, to_host):wait()

tests/unit/protocol_v2_operations_spec.lua

@@ -219,7 +219,6 @@ describe('V2 protocol operations', function()
 
   it('uses direct, location/data, and page response contracts from the V2 fixtures', function()
     local bodies = {
-      ['/api/config'] = fixture('config.json'),
       ['/api/location'] = fixture('location.json'),
       ['/api/provider'] = fixture('provider.json'),
       ['/api/session'] = fixture('session.json'),
@@ -238,23 +237,20 @@ describe('V2 protocol operations', function()
       return path:gsub('^/Users/oujinsai', '/host')
     end
 
-    local config = operations.get_config(connection, location, to_server, to_host):wait()
     local project = operations.get_current_project(connection, location, to_server, to_host):wait()
     local providers = operations.list_providers(connection, location, to_server, to_host):wait()
     local sessions = operations.list_sessions(connection, location, nil, 25, to_server, to_host):wait()
     local provider_fixture = vim.json.decode(bodies['/api/provider'])
     local session_fixture = vim.json.decode(bodies['/api/session'])
 
-    assert.equals('/host/.claude', config[1].path)
     assert.equals('/host/Projects/nvim-plugins/opencode.nvim', project.directory)
     assert.same(provider_fixture.location, providers.location)
     assert.same(provider_fixture.data, providers.data)
     assert.equals(to_host(session_fixture.data[1].location.directory), sessions.data[1].location.directory)
     assert.truthy(sessions.cursor.next)
     assert.equals('location%5Bdirectory%5D=%2Fserver%2Fworkspace', calls[1].request.query)
     assert.equals('location%5Bdirectory%5D=%2Fserver%2Fworkspace', calls[2].request.query)
-    assert.equals('location%5Bdirectory%5D=%2Fserver%2Fworkspace', calls[3].request.query)
-    assert.equals('directory=%2Fserver%2Fworkspace&limit=25', calls[4].request.query)
+    assert.equals('directory=%2Fserver%2Fworkspace&limit=25', calls[3].request.query)
   end)
 
   it('extracts the project object from the location envelope without unwrapping its data field', function()
@@ -275,21 +271,64 @@ describe('V2 protocol operations', function()
     assert.equals('/host/project', result.directory)
   end)
 
-  it('does not unwrap a data field from a direct array response', function()
-    transport.request = function()
-      return Promise.new():resolve({
-        status = 200,
-        body = '[{"data":{"belongs":"to-source"},"path":"/server/config.json"}]',
-      })
+  it('resolves effective model defaults rather than treating config sources as config', function()
+    local calls = {}
+    transport.request = function(_, request)
+      calls[#calls + 1] = request
+      local bodies = {
+        ['/api/model/default'] = '{"data":{"providerID":"opencode-go","id":"glm-5.3-flash"}}',
+        ['/api/agent'] = '{"data":[{"id":"orchestrator","model":{"providerID":"custom","id":"agent-model"}},{"id":"build"}]}',
+      }
+      return Promise.new():resolve({ status = 200, body = assert(bodies[request.path]) })
     end
     local result = operations
-      .get_config(ready_connection(), { directory = '/server/project' }, nil, function(path)
-        return path:gsub('^/server', '/host')
+      .get_config(ready_connection(), { directory = '/host/project' }, function(path)
+        return path:gsub('^/host', '/server')
       end)
       :wait()
 
-    assert.same({ belongs = 'to-source' }, result[1].data)
-    assert.equals('/host/config.json', result[1].path)
+    assert.equals('opencode-go/glm-5.3-flash', result.model)
+    assert.equals('custom/agent-model', result.agent.orchestrator.model)
+    assert.same({}, result.agent.build)
+    for _, call in ipairs(calls) do
+      assert.equals('location%5Bdirectory%5D=%2Fserver%2Fproject', call.query)
+    end
+  end)
+
+  it('encodes neutral session selections without overriding explicit creation options', function()
+    local bodies = {}
+    transport.request = function(_, request)
+      bodies[#bodies + 1] = vim.json.decode(request.body)
+      return Promise.new():resolve({ status = 200, body = '{"data":{"id":"new-session"}}' })
+    end
+    local connection = ready_connection()
+    local location = { directory = '/project' }
+    local selected = { mode = 'orchestrator', model = 'opencode-go/glm-5.3-flash', variant = 'high' }
+    operations.create_session(connection, location, { title = 'Default' }, nil, nil, selected):wait()
+    assert.same({
+      title = 'Default',
+      location = location,
+      agent = 'orchestrator',
+      model = { providerID = 'opencode-go', id = 'glm-5.3-flash', variant = 'high' },
+    }, bodies[1])
+
+    local explicit = { agent = 'other', model = { providerID = 'custom', id = 'chosen' } }
+    operations.create_session(connection, location, explicit, nil, nil, selected):wait()
+    assert.same({ agent = 'other', model = explicit.model, location = location }, bodies[2])
+    assert.is_nil(explicit.location)
+
+    operations.create_session(connection, location, { agent = 'other' }, nil, nil, selected):wait()
+    assert.same({ agent = 'other', location = location }, bodies[3])
+  end)
+
+  it('allows effective configuration without a default model', function()
+    transport.request = function(_, request)
+      return Promise.new():resolve({
+        status = 200,
+        body = request.path == '/api/model/default' and '{"data":null}' or '{"data":[]}',
+      })
+    end
+    assert.same({ agent = {} }, operations.get_config(ready_connection(), { directory = '/project' }):wait())
   end)
 
   it('maps business data without changing a provider envelope location', function()

tests/unit/services_agent_model_spec.lua

@@ -185,6 +185,19 @@ describe('opencode.services.agent_model', function()
     config_file.get_opencode_providers:revert()
   end)
 
+  it('initializes the current agent model before the global default', function()
+    state.model.clear()
+    state.model.set_mode('orchestrator')
+    stub(config_file, 'get_opencode_config').returns(Promise.new():resolve({
+      model = 'opencode/gemini-4-argon',
+      agent = { orchestrator = { model = 'opencode-go/glm-5.3-flash' } },
+    }))
+
+    assert.equal('opencode-go/glm-5.3-flash', agent_model.initialize_current_model():wait())
+
+    config_file.get_opencode_config:revert()
+  end)
+
   it('restores the latest session model and mode when explicitly requested', function()
     state.model.set_model('openai/gpt-4.1')
     state.model.set_mode('plan')
@@ -207,6 +220,30 @@ describe('opencode.services.agent_model', function()
     config_file.get_opencode_agents:revert()
   end)
 
+  it('resolves a neutral session selection while preserving explicit choices', function()
+    state.model.set_mode('plan')
+    state.model.set_model('custom/chosen')
+    state.model.set_variant('high')
+    stub(config_file, 'get_opencode_agents').returns(Promise.new():resolve({ 'plan' }))
+
+    local selected = agent_model.resolve_session_selection():wait()
+
+    assert.same({ mode = 'plan', model = 'custom/chosen', variant = 'high' }, selected)
+    config_file.get_opencode_agents:revert()
+  end)
+
+  it('rejects session selection when no primary agent is available', function()
+    stub(config_file, 'get_opencode_agents').returns(Promise.new():resolve({}))
+
+    local ok, err = pcall(function()
+      agent_model.resolve_session_selection():wait()
+    end)
+
+    config_file.get_opencode_agents:revert()
+    assert.is_false(ok)
+    assert.matches('Cannot resolve session agent', tostring(err))
+  end)
+
   it('restores hidden mode from messages for child sessions', function()
     state.model.set_model('openai/gpt-4.1')
     state.model.set_mode('build')