diff --git a/.gitea/workflows/publish-workspace-server-image.yml b/.gitea/workflows/publish-workspace-server-image.yml
index 96a03b7e..08a65d14 100644
--- a/.gitea/workflows/publish-workspace-server-image.yml
+++ b/.gitea/workflows/publish-workspace-server-image.yml
@@ -23,7 +23,7 @@ name: publish-workspace-server-image
 
 on:
   push:
-    branches: [staging, main]
+    branches: [main]
     paths:
       - 'workspace-server/**'
       - 'canvas/**'
@@ -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/.github/workflows/publish-workspace-server-image.yml b/.github/workflows/publish-workspace-server-image.yml
index be88f2cc..2a1b8b17 100644
--- a/.github/workflows/publish-workspace-server-image.yml
+++ b/.github/workflows/publish-workspace-server-image.yml
@@ -32,7 +32,7 @@ name: publish-workspace-server-image
 
 on:
   push:
-    branches: [staging, main]
+    branches: [main]
     paths:
       - 'workspace-server/**'
       - 'canvas/**'
diff --git a/workspace/builtin_tools/a2a_tools.py b/workspace/builtin_tools/a2a_tools.py
index df4f9d78..d9c48598 100644
--- a/workspace/builtin_tools/a2a_tools.py
+++ b/workspace/builtin_tools/a2a_tools.py
@@ -66,10 +66,23 @@ async def delegate_task(workspace_id: str, task: str) -> str:
             )
             data = a2a_resp.json()
             if "result" in data:
-                parts = data["result"].get("parts", [])
-                return parts[0].get("text", "(no text)") if parts else str(data["result"])
+                result = data["result"]
+                parts = result.get("parts", []) if isinstance(result, dict) else []
+                if parts and isinstance(parts[0], dict):
+                    return parts[0].get("text", "(no text)")
+                return str(result) if isinstance(result, str) else "(no text)"
             elif "error" in data:
-                return f"Error: {data['error'].get('message', str(data['error']))}"
+                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}"
             return str(data)
         except Exception as e:
             return f"Error sending A2A message: {e}"