Merge milestone/v1.16-nova-simplification — v1.16 complete (Nova Simplification: 20-phase NFR sweep + final; tag v1.15.26)

scripts/migrate_ssm_paths.py

@@ -110,8 +110,18 @@ def copy_one_param(client, source_name: str, dest_name: str, force: bool = False
             return "skipped-equal"
         if not force:
             return "skipped-mismatch"
-    except Exception:  # ParameterNotFound → proceed to put
-        pass
+    except client.exceptions.ParameterNotFound:
+        pass  # target doesn't exist yet → proceed to put
+    except Exception as e:
+        # P4 (REQ-168): narrow the broad swallow — only ParameterNotFound
+        # is an expected "proceed to put" condition. Any other AWS error
+        # (auth, throttling, service) must surface, not be swallowed.
+        import sys
+        sys.stderr.write(
+            f"migrate_ssm_paths: get_parameter({dest_name}) failed: "
+            f"{type(e).__name__}: {e}\n"
+        )
+        raise
 
     put_kwargs = {
         "Name": dest_name,