require a2a pack write prefix support

agent_builder/skills/deepagents-implementation-patterns/SKILL.md

@@ -21,12 +21,12 @@ from langchain_core.tools import tool
 from langchain_openai import ChatOpenAI
 from deepagents import create_deep_agent
 
-RUNTIME_SKILLS_ROOT = "/outputs/research-agent/.deepagents/skills/"
+RUNTIME_SKILLS_DIR = "research-agent/.deepagents/skills/"
 
 SYSTEM_PROMPT = """\
 You are a careful research agent. Use project skills for workflow rules and
 use workspace-backed tools for durable files. Prefer /workspace/outputs/ for
-stable output paths.
+stable output paths only when that is one of the grant write prefixes.
 """
 
 
@@ -50,7 +50,7 @@ def build_graph(ctx: Any) -> Any:
         return json.dumps({"ok": not missing, "missing_indexes": missing})
 
     backend = ctx.workspace_backend()
-    skill_sources = seed_runtime_skills(backend)
+    skill_sources = seed_runtime_skills(backend, ctx)
     return create_deep_agent(
         model=model,
         backend=backend,
@@ -71,18 +71,29 @@ def build_graph(ctx: Any) -> Any:
     )
 
 
-def seed_runtime_skills(backend: Any) -> list[str]:
+def runtime_skills_root(ctx: Any) -> str:
+    workspace = getattr(ctx, "_workspace", None)
+    prefixes = tuple(getattr(workspace, "write_prefixes", ()) or ())
+    if not prefixes:
+        outputs_prefix = getattr(workspace, "outputs_prefix", None)
+        prefixes = (outputs_prefix or "outputs/",)
+    prefix = str(prefixes[0]).strip("/")
+    return f"/{prefix}/{RUNTIME_SKILLS_DIR}" if prefix else f"/{RUNTIME_SKILLS_DIR}"
+
+
+def seed_runtime_skills(backend: Any, ctx: Any) -> list[str]:
     root = Path(__file__).parent / "skills"
     if not root.exists():
         return []
+    runtime_root = runtime_skills_root(ctx)
     uploads: list[tuple[str, bytes]] = []
     for path in root.rglob("*"):
         if path.is_file():
             rel = path.relative_to(root).as_posix()
-            uploads.append((RUNTIME_SKILLS_ROOT + rel, path.read_bytes()))
+            uploads.append((runtime_root + rel, path.read_bytes()))
     if uploads:
         backend.upload_files(uploads)
-        return [RUNTIME_SKILLS_ROOT]
+        return [runtime_root]
     return []
 ```