diff --git a/.gitea/workflows/publish-workspace-server-image.yml b/.gitea/workflows/publish-workspace-server-image.yml
index e9ca5ec2..08a65d14 100644
--- a/.gitea/workflows/publish-workspace-server-image.yml
+++ b/.gitea/workflows/publish-workspace-server-image.yml
@@ -32,11 +32,9 @@ on:
       - '.gitea/workflows/publish-workspace-server-image.yml'
   workflow_dispatch:
 
-# Serialize per-branch so two rapid staging pushes don't race the same
-# :staging-latest tag retag. Allow staging and main to run in parallel
-# (different GITHUB_REF → different concurrency group) since they
-# produce different :staging-<sha> tags and last-write-wins on
-# :staging-latest is acceptable across branches.
+# Serialize per-branch so two rapid main pushes don't race the same
+# :staging-latest tag retag. Allow parallel runs as they produce
+# different :staging-<sha> tags and last-write-wins on :staging-latest.
 #
 # cancel-in-progress: false → in-flight builds finish; the next push's
 # build queues. This avoids a partially-pushed image.
diff --git a/workspace/builtin_tools/a2a_tools.py b/workspace/builtin_tools/a2a_tools.py
index acdd15cb..48b813a1 100644
--- a/workspace/builtin_tools/a2a_tools.py
+++ b/workspace/builtin_tools/a2a_tools.py
@@ -77,6 +77,16 @@ async def delegate_task(workspace_id: str, task: str) -> str:
                 return str(result) if isinstance(result, str) else "(no text)"
             elif "error" in data:
                 err = data["error"]
+                # Handle both string-form errors ("error": "some string")
+                # and object-form errors ("error": {"message": "...", "code": ...}).
+                msg = ""
+                if isinstance(err, dict):
+                    msg = err.get("message", "")
+                elif isinstance(err, str):
+                    msg = err
+                else:
+                    msg = str(err)
+                return f"Error: {msg}"
                 msg = ""
                 if isinstance(err, dict):
                     msg = err.get("message", "")