Teach builder to author DeepAgents skills

tests/test_builder_prompt.py

@@ -2,7 +2,13 @@ from __future__ import annotations
 
 import unittest
 
-from agent_builder.builder import SYSTEM_PROMPT
+from agent_builder.builder import (
+    BUILDER_SKILL_SOURCE,
+    SYSTEM_PROMPT,
+    _builder_skill_files,
+    _with_builder_skills,
+)
+from deepagents.backends import StateBackend
 
 
 class BuilderPromptTests(unittest.TestCase):
@@ -17,3 +23,33 @@ class BuilderPromptTests(unittest.TestCase):
         self.assertIn("class GeneratedDeck(Slide)", SYSTEM_PROMPT)
         self.assertIn("manim-slides render --CE -ql", SYSTEM_PROMPT)
         self.assertIn("render: bool = False", SYSTEM_PROMPT)
+
+    def test_prompt_and_backend_load_packaged_builder_skills(self) -> None:
+        expected = {
+            "deepagent-agent-design",
+            "a2apack-agent-authoring",
+            "deepagents-implementation-patterns",
+            "workspace-artifact-safety",
+            "agent-quality-review",
+        }
+        for skill_name in expected:
+            self.assertIn(skill_name, SYSTEM_PROMPT)
+        self.assertIn("deepagent-agent-design", SYSTEM_PROMPT)
+        self.assertIn("write_agent_skill", SYSTEM_PROMPT)
+        self.assertIn("workspace_access = WorkspaceAccess.dynamic", SYSTEM_PROMPT)
+
+        files = _builder_skill_files()
+        self.assertTrue(
+            {path.split("/", 1)[0] for path in files}.issuperset(expected)
+        )
+        self.assertIn("skills=[RUNTIME_SKILLS_ROOT]", files["deepagent-agent-design/SKILL.md"])
+        self.assertIn("from a2a_pack import", files["a2apack-agent-authoring/SKILL.md"])
+        self.assertIn("create_deep_agent", files["deepagents-implementation-patterns/SKILL.md"])
+        self.assertIn("ctx.write_artifact", files["workspace-artifact-safety/SKILL.md"])
+        self.assertIn("live_skills[].input_schema", files["agent-quality-review/SKILL.md"])
+
+        backend = _with_builder_skills(StateBackend())
+        listing = backend.ls(BUILDER_SKILL_SOURCE)
+        paths = [entry["path"] for entry in (listing.entries or [])]
+        for skill_name in expected:
+            self.assertIn(f"{BUILDER_SKILL_SOURCE}{skill_name}/", paths)