Merge agent and mode into one (#1689)

The concept of mode has been deprecated, there is now only the agent field in the config.

An agent can be cycled through as your primary agent with <tab> or you can spawn a subagent by @ mentioning it. if you include a description of when to use it, the primary agent will try to automatically use it

Full docs here: https://opencode.ai/docs/agents/

packages/opencode/src/cli/cmd/tui.ts

@@ -11,8 +11,8 @@ import { Config } from "../../config/config"
 import { Bus } from "../../bus"
 import { Log } from "../../util/log"
 import { FileWatcher } from "../../file/watch"
-import { Mode } from "../../session/mode"
 import { Ide } from "../../ide"
+import { Agent } from "../../agent/agent"
 
 declare global {
   const OPENCODE_TUI_PATH: string
@@ -115,7 +115,7 @@ export const TuiCommand = cmd({
             CGO_ENABLED: "0",
             OPENCODE_SERVER: server.url.toString(),
             OPENCODE_APP_INFO: JSON.stringify(app),
-            OPENCODE_MODES: JSON.stringify(await Mode.list()),
+            OPENCODE_AGENTS: JSON.stringify(await Agent.list()),
           },
           onExit: () => {
             server.stop()