fix: add checkpoints at task start, attempt_completion, and mode switch

- Add checkpoint creation at task start to allow reverting to the beginning
- Add checkpoint creation when attempt_completion is called to mark task completion
- Add checkpoint creation before mode switches to preserve state before mode change
- All checkpoints use suppressMessage flag to keep timeline clean

Fixes #8458

Author: roomote

src/core/task/Task.ts

@@ -1219,6 +1219,11 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 
 		// Task starting
 
+		// Create a checkpoint at task start to allow reverting to the beginning
+		// Use allowEmpty=true to ensure checkpoint is created even with no file changes
+		// Suppress the checkpoint_saved chat row to keep the timeline clean
+		await this.checkpointSave(true, true)
+
 		await this.initiateTaskLoop([
 			{
 				type: "text",

src/core/tools/attemptCompletionTool.ts

@@ -89,6 +89,11 @@ export async function attemptCompletionTool(
 
 			cline.consecutiveMistakeCount = 0
 
+			// Create a checkpoint when task is completed
+			// Use allowEmpty=true to ensure checkpoint is created even with no file changes
+			// Suppress the checkpoint_saved chat row to keep the timeline clean
+			await cline.checkpointSave(true, true)
+
 			// Command execution is permanently disabled in attempt_completion
 			// Users must use execute_command tool separately before attempt_completion
 			await cline.say("completion_result", result, undefined, false)

src/core/tools/switchModeTool.ts

@@ -61,6 +61,11 @@ export async function switchModeTool(
 				return
 			}
 
+			// Create a checkpoint before switching modes
+			// Use allowEmpty=true to ensure checkpoint is created even with no file changes
+			// Suppress the checkpoint_saved chat row to keep the timeline clean
+			await cline.checkpointSave(true, true)
+
 			// Switch the mode using shared handler
 			await cline.providerRef.deref()?.handleModeSwitch(mode_slug)