fix: Re-export DEFAULT_SKILL_SYSTEM_INSTRUCTION to skills and skill/prompt.py to avoid breaking current users

Co-authored-by: Kathy Wu <wukathy@google.com>
PiperOrigin-RevId: 875407169

Author: wukath

src/google/adk/skills/__init__.py

@@ -14,16 +14,38 @@
 
 """Agent Development Kit - Skills."""
 
+from typing import Any
+import warnings
+
 from ._utils import _load_skill_from_dir as load_skill_from_dir
 from .models import Frontmatter
 from .models import Resources
 from .models import Script
 from .models import Skill
 
 __all__ = [
+    "DEFAULT_SKILL_SYSTEM_INSTRUCTION",
     "Frontmatter",
     "Resources",
     "Script",
     "Skill",
     "load_skill_from_dir",
 ]
+
+
+def __getattr__(name: str) -> Any:
+  if name == "DEFAULT_SKILL_SYSTEM_INSTRUCTION":
+
+    from ..tools import skill_toolset
+
+    warnings.warn(
+        (
+            "Importing DEFAULT_SKILL_SYSTEM_INSTRUCTION from"
+            " google.adk.skills is deprecated."
+            " Please import it from google.adk.tools.skill_toolset instead."
+        ),
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    return skill_toolset.DEFAULT_SKILL_SYSTEM_INSTRUCTION
+  raise AttributeError(f"module {__name__} has no attribute {name}")

src/google/adk/skills/prompt.py

@@ -17,8 +17,10 @@
 from __future__ import annotations
 
 import html
+from typing import Any
 from typing import List
 from typing import Union
+import warnings
 
 from . import models
 
@@ -54,3 +56,21 @@ def format_skills_as_xml(
   lines.append("</available_skills>")
 
   return "\n".join(lines)
+
+
+def __getattr__(name: str) -> Any:
+  if name == "DEFAULT_SKILL_SYSTEM_INSTRUCTION":
+
+    from ..tools import skill_toolset
+
+    warnings.warn(
+        (
+            "Importing DEFAULT_SKILL_SYSTEM_INSTRUCTION from"
+            " google.adk.skills.prompt is deprecated."
+            " Please import it from google.adk.tools.skill_toolset instead."
+        ),
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    return skill_toolset.DEFAULT_SKILL_SYSTEM_INSTRUCTION
+  raise AttributeError(f"module {__name__} has no attribute {name}")