diff --git a/src/specify_cli/workflows/catalog/_domain.py b/src/specify_cli/workflows/catalog/_domain.py
index cc29a0b0ca..18bc0165a6 100644
--- a/src/specify_cli/workflows/catalog/_domain.py
+++ b/src/specify_cli/workflows/catalog/_domain.py
@@ -805,10 +805,11 @@ def _coerce_priority(value: Any) -> int:
                 # existing priority as 0 rather than crashing 'catalog add'.
                 return 0
 
+        # Match the config parser's one-based default for omitted priorities.
         max_priority = max(
             (
-                _coerce_priority(cat.get("priority", 0))
-                for cat in catalogs
+                _coerce_priority(cat.get("priority", idx + 1))
+                for idx, cat in enumerate(catalogs)
                 if isinstance(cat, dict)
             ),
             default=0,
diff --git a/src/specify_cli/workflows/step/catalog/_domain.py b/src/specify_cli/workflows/step/catalog/_domain.py
index 1f0e2503d8..4ed99a140b 100644
--- a/src/specify_cli/workflows/step/catalog/_domain.py
+++ b/src/specify_cli/workflows/step/catalog/_domain.py
@@ -741,10 +741,11 @@ def _coerce_priority(value: Any) -> int:
                 # existing priority as 0 rather than crashing 'catalog add'.
                 return 0
 
+        # Match the config parser's one-based default for omitted priorities.
         max_priority = max(
             (
-                _coerce_priority(cat.get("priority", 0))
-                for cat in catalogs
+                _coerce_priority(cat.get("priority", idx + 1))
+                for idx, cat in enumerate(catalogs)
                 if isinstance(cat, dict)
             ),
             default=0,
diff --git a/tests/specify_cli/workflows/catalog/test_domain.py b/tests/specify_cli/workflows/catalog/test_domain.py
new file mode 100644
index 0000000000..35d81aec1b
--- /dev/null
+++ b/tests/specify_cli/workflows/catalog/test_domain.py
@@ -0,0 +1,43 @@
+"""Regression tests for workflow catalog source ordering."""
+
+import pytest
+import yaml
+
+from specify_cli.workflows.catalog import WorkflowCatalog
+
+
+@pytest.mark.parametrize(
+    ("priorities", "expected_priorities"),
+    [
+        ([None, None, None], [1, 2, 3, 4]),
+        ([1, None, None], [1, 2, 3, 4]),
+        ([10, "20", 30], [10, 20, 30, 31]),
+        ([-3, -2, -1], [-3, -2, -1, 0]),
+    ],
+    ids=["implicit", "mixed", "explicit", "negative"],
+)
+def test_add_catalog_appends_after_effective_priorities(
+    project_dir, monkeypatch, priorities, expected_priorities
+):
+    monkeypatch.delenv("SPECKIT_WORKFLOW_CATALOG_URL", raising=False)
+    config_path = project_dir / ".specify" / "workflow-catalogs.yml"
+    entries = [
+        {"name": name, "url": f"https://{name}.example/catalog.json"}
+        for name in ("first", "second", "third")
+    ]
+    for entry, priority in zip(entries, priorities):
+        if priority is not None:
+            entry["priority"] = priority
+    config_path.write_text(yaml.safe_dump({"catalogs": entries}), encoding="utf-8")
+
+    catalog = WorkflowCatalog(project_dir)
+    assert catalog.add_catalog("https://added.example/catalog.json", "added") == "added"
+
+    configs = WorkflowCatalog(project_dir).get_catalog_configs()
+    assert [config["name"] for config in configs] == [
+        "first", "second", "third", "added"
+    ]
+    assert [config["priority"] for config in configs] == expected_priorities
+    stored = yaml.safe_load(config_path.read_text(encoding="utf-8"))["catalogs"]
+    assert stored[:-1] == entries
+    assert stored[-1]["priority"] == expected_priorities[-1]
diff --git a/tests/specify_cli/workflows/step/catalog/test_domain.py b/tests/specify_cli/workflows/step/catalog/test_domain.py
new file mode 100644
index 0000000000..837e986eca
--- /dev/null
+++ b/tests/specify_cli/workflows/step/catalog/test_domain.py
@@ -0,0 +1,43 @@
+"""Regression tests for workflow step catalog source ordering."""
+
+import pytest
+import yaml
+
+from specify_cli.workflows.step.catalog import StepCatalog
+
+
+@pytest.mark.parametrize(
+    ("priorities", "expected_priorities"),
+    [
+        ([None, None, None], [1, 2, 3, 4]),
+        ([1, None, None], [1, 2, 3, 4]),
+        ([10, "20", 30], [10, 20, 30, 31]),
+        ([-3, -2, -1], [-3, -2, -1, 0]),
+    ],
+    ids=["implicit", "mixed", "explicit", "negative"],
+)
+def test_add_catalog_appends_after_effective_priorities(
+    project_dir, monkeypatch, priorities, expected_priorities
+):
+    monkeypatch.delenv("SPECKIT_STEP_CATALOG_URL", raising=False)
+    config_path = project_dir / ".specify" / "step-catalogs.yml"
+    entries = [
+        {"name": name, "url": f"https://{name}.example/catalog.json"}
+        for name in ("first", "second", "third")
+    ]
+    for entry, priority in zip(entries, priorities):
+        if priority is not None:
+            entry["priority"] = priority
+    config_path.write_text(yaml.safe_dump({"catalogs": entries}), encoding="utf-8")
+
+    catalog = StepCatalog(project_dir)
+    assert catalog.add_catalog("https://added.example/catalog.json", "added") == "added"
+
+    configs = StepCatalog(project_dir).get_catalog_configs()
+    assert [config["name"] for config in configs] == [
+        "first", "second", "third", "added"
+    ]
+    assert [config["priority"] for config in configs] == expected_priorities
+    stored = yaml.safe_load(config_path.read_text(encoding="utf-8"))["catalogs"]
+    assert stored[:-1] == entries
+    assert stored[-1]["priority"] == expected_priorities[-1]