fix: preserve tool failures under noisy output

agent_platform/gateway/provider.py

@@ -19,6 +19,7 @@ from docker.errors import ImageNotFound, NotFound
 import docker
 from agent_platform.config import Settings
 from agent_platform.gateway.schemas import ToolResult, WorkspaceListing, WorkspaceStatus
+from agent_platform.text import truncate_middle
 
 
 def normalize_workspace_path(raw_path: str) -> PurePosixPath:
@@ -208,7 +209,7 @@ class DockerExecutionProvider:
             output = ((stdout or b"") + (stderr or b"")).decode("utf-8", errors="replace")
             truncated = len(output) > max_output
             if truncated:
-                output = output[:max_output] + "\n… output truncated …"
+                output = truncate_middle(output, max_output, "\n… output truncated; middle omitted …\n")
             return ToolResult(
                 ok=result.exit_code == 0,
                 output=output,