fix(copilot): auto-cleanup worktree after successful --apply

When --apply successfully applies changes from the worktree to the main
project, automatically clean up the worktree with force since the changes
have already been extracted. Also updated hint messages to suggest using
--force with cleanup command.

Author: ThomasRohde

src/klondike_spec_cli/copilot.py

@@ -158,81 +158,60 @@ def build_prompt(
     instructions: str | None = None,
     worktree_info: WorktreeInfo | None = None,
 ) -> str:
-    """Build the prompt for Copilot.
+    """Build a brief prompt for Copilot.
+
+    Behavioral rules and project context come from .github/copilot-instructions.md
+    which Copilot CLI auto-loads. This function only needs to specify the task.
 
     Args:
         focus_feature: Optional feature to focus on
         instructions: Additional instructions
         worktree_info: Worktree information if running in worktree
 
     Returns:
-        The prompt string
+        The prompt string (brief task description)
     """
     prompt_parts: list[str] = []
 
     if worktree_info:
-        # ULTRA-DIRECT PROMPT for worktree mode
-        # Previous attempts: Copilot was doing "startup routine" instead of implementing
-        # This version: Feature implementation is THE ONLY GOAL
+        # Worktree mode - Copilot reads .github/copilot-instructions.md for rules
+        # We only need to specify WHAT to do, not HOW to behave
 
         if focus_feature:
-            # Put the feature FIRST, make it the only thing that matters
-            prompt_parts.append(f"# IMPLEMENT: {focus_feature.id} - {focus_feature.description}")
-            prompt_parts.append("")
-            prompt_parts.append("Your ONLY task is to implement this feature. Nothing else.")
+            # Feature implementation task
+            prompt_parts.append(f"Implement {focus_feature.id}: {focus_feature.description}")
             prompt_parts.append("")
             if focus_feature.acceptance_criteria:
-                prompt_parts.append("## Requirements (implement ALL):")
+                prompt_parts.append("Acceptance criteria:")
                 for ac in focus_feature.acceptance_criteria:
                     prompt_parts.append(f"- {ac}")
                 prompt_parts.append("")
-            prompt_parts.append("## Instructions")
-            prompt_parts.append("1. Read the codebase to understand the project structure")
-            prompt_parts.append("2. Write the code to implement this feature")
             prompt_parts.append(
-                "3. Commit when done: git add -A && git commit -m 'feat(F0XX): description'"
+                "You are in an isolated git worktree. Implement the feature and commit when done."
             )
-            prompt_parts.append("")
-            prompt_parts.append("You are in an isolated git worktree - safe to make changes.")
-            prompt_parts.append("")
-            prompt_parts.append("## What NOT to do")
-            prompt_parts.append(
-                "- Do NOT run `klondike status`, `klondike validate`, or `klondike session start`"
-            )
-            prompt_parts.append("- Do NOT do a 'startup routine' or 'orientation'")
-            prompt_parts.append("- Do NOT ask for permission - just implement")
-            prompt_parts.append("")
-            prompt_parts.append("## What you CAN do")
-            prompt_parts.append("- Read files, run the dev server, run tests/lints")
-            prompt_parts.append(
-                "- Use `klondike feature show` if you need more context on a feature"
-            )
-            prompt_parts.append("- Make commits as you work")
         else:
-            # No feature specified - general worktree session
-            prompt_parts.append("# Worktree Session")
-            prompt_parts.append("")
-            prompt_parts.append("You are in an isolated git worktree.")
+            # No feature specified - let Copilot pick based on klondike status
             prompt_parts.append(
-                "Run `klondike status` to see available features, then implement one."
+                "Run `klondike status` to see the project state and pick a feature to implement."
             )
+            prompt_parts.append("You are in an isolated git worktree.")
     else:
-        # Normal mode - use template
+        # Normal mode - use template for session startup
         template_content = _load_prompt_template("session-start.prompt.md")
         prompt_parts.append(template_content)
 
-        # Add feature implementation instruction if specified
+        # Add feature focus if specified
         if focus_feature:
             prompt_parts.append("")
             prompt_parts.append(
-                f"After completing the session start routine, implement feature {focus_feature.id}: {focus_feature.description}"
+                f"Focus on implementing {focus_feature.id}: {focus_feature.description}"
             )
             if focus_feature.acceptance_criteria:
                 prompt_parts.append("Acceptance criteria:")
                 for ac in focus_feature.acceptance_criteria:
-                    prompt_parts.append(f"  - {ac}")
+                    prompt_parts.append(f"- {ac}")
 
-    # Additional instructions
+    # Additional instructions from CLI
     if instructions:
         prompt_parts.append("")
         prompt_parts.append(instructions)
@@ -460,10 +439,18 @@ def _handle_worktree_cleanup(worktree_info: WorktreeInfo, config: CopilotConfig)
             try:
                 apply_worktree_changes(worktree_info)
                 echo("   ✅ Changes applied successfully")
+
+                # Auto-cleanup after successful apply (changes are now in main project)
+                echo("   🧹 Cleaning up worktree...")
+                try:
+                    cleanup_worktree(worktree_info, force=True)
+                    echo("   ✅ Worktree removed")
+                except WorktreeError as e:
+                    echo(f"   ⚠️  Failed to cleanup: {e}")
+                    echo("   💡 Run: klondike copilot cleanup --force")
             except WorktreeError as e:
                 raise PithException(f"Failed to apply changes: {e}") from e
-
-        if config.cleanup_after:
+        elif config.cleanup_after:
             echo("   🧹 Cleaning up worktree...")
             try:
                 cleanup_worktree(worktree_info, force=True)
@@ -474,7 +461,7 @@ def _handle_worktree_cleanup(worktree_info: WorktreeInfo, config: CopilotConfig)
             echo("")
             echo("💡 Worktree preserved. To manage:")
             echo(f"   cd {worktree_info.worktree_path}")
-            echo("   # Or cleanup with: klondike copilot cleanup")
+            echo("   # Or cleanup with: klondike copilot cleanup --force")
     else:
         echo("   ℹ️  No changes detected")