feat: make plan mode the default, remove experimental flag

- Remove OPENCODE_EXPERIMENTAL_PLAN_MODE flag from flag.ts
- Update prompt.ts to always use plan mode logic
- Update registry.ts to always include plan tools in CLI
- Remove flag documentation from cli.mdx

packages/opencode/src/flag/flag.ts

@@ -44,7 +44,7 @@ export namespace Flag {
   export const OPENCODE_EXPERIMENTAL_LSP_TY = truthy("OPENCODE_EXPERIMENTAL_LSP_TY")
   export const OPENCODE_EXPERIMENTAL_LSP_TOOL = OPENCODE_EXPERIMENTAL || truthy("OPENCODE_EXPERIMENTAL_LSP_TOOL")
   export const OPENCODE_DISABLE_FILETIME_CHECK = truthy("OPENCODE_DISABLE_FILETIME_CHECK")
-  export const OPENCODE_EXPERIMENTAL_PLAN_MODE = OPENCODE_EXPERIMENTAL || truthy("OPENCODE_EXPERIMENTAL_PLAN_MODE")
+
   export const OPENCODE_EXPERIMENTAL_MARKDOWN = truthy("OPENCODE_EXPERIMENTAL_MARKDOWN")
   export const OPENCODE_MODELS_URL = process.env["OPENCODE_MODELS_URL"]
   export const OPENCODE_MODELS_PATH = process.env["OPENCODE_MODELS_PATH"]

packages/opencode/src/session/prompt.ts

@@ -1232,33 +1232,7 @@ export namespace SessionPrompt {
     const userMessage = input.messages.findLast((msg) => msg.info.role === "user")
     if (!userMessage) return input.messages
 
-    // Original logic when experimental plan mode is disabled
-    if (!Flag.OPENCODE_EXPERIMENTAL_PLAN_MODE) {
-      if (input.agent.name === "plan") {
-        userMessage.parts.push({
-          id: Identifier.ascending("part"),
-          messageID: userMessage.info.id,
-          sessionID: userMessage.info.sessionID,
-          type: "text",
-          text: PROMPT_PLAN,
-          synthetic: true,
-        })
-      }
-      const wasPlan = input.messages.some((msg) => msg.info.role === "assistant" && msg.info.agent === "plan")
-      if (wasPlan && input.agent.name === "build") {
-        userMessage.parts.push({
-          id: Identifier.ascending("part"),
-          messageID: userMessage.info.id,
-          sessionID: userMessage.info.sessionID,
-          type: "text",
-          text: BUILD_SWITCH,
-          synthetic: true,
-        })
-      }
-      return input.messages
-    }
-
-    // New plan mode logic when flag is enabled
+    // Plan mode logic
     const assistantMessage = input.messages.findLast((msg) => msg.info.role === "assistant")
 
     // Switching from plan mode to build mode

packages/opencode/src/tool/registry.ts

@@ -117,7 +117,7 @@ export namespace ToolRegistry {
       ApplyPatchTool,
       ...(Flag.OPENCODE_EXPERIMENTAL_LSP_TOOL ? [LspTool] : []),
       ...(config.experimental?.batch_tool === true ? [BatchTool] : []),
-      ...(Flag.OPENCODE_EXPERIMENTAL_PLAN_MODE && Flag.OPENCODE_CLIENT === "cli" ? [PlanExitTool, PlanEnterTool] : []),
+      ...(Flag.OPENCODE_CLIENT === "cli" ? [PlanExitTool, PlanEnterTool] : []),
       ...custom,
     ]
   }

packages/web/src/content/docs/cli.mdx

@@ -594,4 +594,3 @@ These environment variables enable experimental features that may change or be r
 | `OPENCODE_EXPERIMENTAL_EXA`                     | boolean | Enable experimental Exa features        |
 | `OPENCODE_EXPERIMENTAL_LSP_TY`                  | boolean | Enable experimental LSP type checking   |
 | `OPENCODE_EXPERIMENTAL_MARKDOWN`                | boolean | Enable experimental markdown features   |
-| `OPENCODE_EXPERIMENTAL_PLAN_MODE`               | boolean | Enable plan mode                        |