fix: persist builder deepagent files

agent_builder/builder.py

@@ -16,6 +16,7 @@ class BuilderContext:
     bucket: str
     cp_jwt: str | None = None
     settings: Settings | None = None
+    project_prefix: str | None = None
     # Optional caller-provided LLM creds (when the outer platform Card
     # declares llm_provisioning=caller_provided). Falls back to settings.
     llm_base_url: str | None = None
@@ -128,6 +129,58 @@ def build_agent_builder(ctx: BuilderContext) -> Any:
         api_key=ctx.llm_api_key or settings.litellm_key,
         temperature=0.0,
     )
-    return create_deep_agent(
-        model=model, tools=tools, system_prompt=SYSTEM_PROMPT,
+    kwargs: dict[str, Any] = {
+        "model": model,
+        "tools": tools,
+        "system_prompt": SYSTEM_PROMPT,
+    }
+    backend = _build_project_backend(ctx, settings=settings)
+    if backend is not None:
+        kwargs["backend"] = backend
+    return create_deep_agent(**kwargs)
+
+
+def _build_project_backend(ctx: BuilderContext, *, settings: Settings) -> Any | None:
+    """Persist DeepAgents built-in file tools into this project directory.
+
+    The explicit builder tools remain the preferred path, but this prevents
+    a model-selected DeepAgents ``write_file`` from disappearing into
+    LangGraph state. Scope it to the project prefix, not the whole bucket.
+    """
+    if not ctx.project_prefix:
+        return None
+    prefix = ctx.project_prefix.strip("/")
+    if not prefix:
+        return None
+    try:
+        from a2a_pack import Grant, WorkspaceAccess, WorkspaceMode
+        from a2a_pack.deepagents import WorkspaceBackend
+        from a2a_pack.workspace import MinIOWorkspaceClient
+    except Exception:  # noqa: BLE001
+        return None
+
+    workspace = MinIOWorkspaceClient(
+        bucket=ctx.bucket,
+        endpoint_url=settings.minio_endpoint,
+        access_key_id=settings.minio_access_key,
+        secret_access_key=settings.minio_secret_key,
+        access=WorkspaceAccess.dynamic(
+            max_files=2000,
+            allowed_modes=(WorkspaceMode.READ_ONLY, WorkspaceMode.READ_WRITE_OVERLAY),
+            require_reason=False,
+        ),
+        issuer="agent-builder",
     )
+    workspace.install_grant(
+        Grant(
+            grant_id=f"agent-builder-{prefix.replace('/', '-')}",
+            issuer="agent-builder",
+            audience="agent-builder",
+            bucket=ctx.bucket,
+            mode=WorkspaceMode.READ_WRITE_OVERLAY,
+            allow_patterns=(f"{prefix}/**", "outputs/**"),
+            deny_patterns=(),
+            outputs_prefix=None,
+        )
+    )
+    return WorkspaceBackend(workspace)