feat: clearer fatal error messages for missing API keys and images

src/vectrify/main.py

@@ -31,12 +31,20 @@ def determine_provider_and_model(args) -> tuple[str, str]:
         elif os.getenv("GEMINI_API_KEY"):
             provider = "gemini"
         else:
-            print("CRITICAL: No API key found.", file=sys.stderr)
+            print(
+                "Error: no LLM API key found. Set one of OPENAI_API_KEY, "
+                "ANTHROPIC_API_KEY, or GEMINI_API_KEY in your environment.",
+                file=sys.stderr,
+            )
             sys.exit(1)
     else:
         env_var = f"{provider.upper()}_API_KEY"
         if not os.getenv(env_var):
-            print(f"CRITICAL: {env_var} not set.", file=sys.stderr)
+            print(
+                f"Error: --provider {provider} was selected but {env_var} is "
+                f"not set. Export {env_var} or pick a provider whose key is set.",
+                file=sys.stderr,
+            )
             sys.exit(1)
 
     if not model:
@@ -115,8 +123,11 @@ def main():
     except KeyboardInterrupt:
         print("\nSearch interrupted by user. Exiting safely...", file=sys.stderr)
         sys.exit(130)
+    except FileNotFoundError:
+        print(f"Error: input image not found: {args.image}", file=sys.stderr)
+        sys.exit(1)
     except Exception as e:
-        print(f"FATAL: {e}", file=sys.stderr)
+        print(f"Error: {e}", file=sys.stderr)
         sys.exit(1)
 
 

src/vectrify/tests/test_main.py

@@ -0,0 +1,56 @@
+import argparse
+
+import pytest
+
+from vectrify.main import determine_provider_and_model
+
+_KEYS = ("OPENAI_API_KEY", "ANTHROPIC_API_KEY", "GEMINI_API_KEY")
+
+
+@pytest.fixture
+def clear_keys(monkeypatch):
+    for key in _KEYS:
+        monkeypatch.delenv(key, raising=False)
+
+
+def _args(**kwargs):
+    defaults = {"provider": "auto", "model": None}
+    defaults.update(kwargs)
+    return argparse.Namespace(**defaults)
+
+
+@pytest.mark.usefixtures("clear_keys")
+def test_auto_no_key_errors_and_names_env_vars(capsys):
+    with pytest.raises(SystemExit) as exc:
+        determine_provider_and_model(_args())
+    assert exc.value.code == 1
+    err = capsys.readouterr().err
+    assert all(name in err for name in _KEYS)
+    assert err.startswith("Error:")
+
+
+@pytest.mark.usefixtures("clear_keys")
+def test_explicit_provider_missing_key_names_var(capsys):
+    with pytest.raises(SystemExit) as exc:
+        determine_provider_and_model(_args(provider="anthropic"))
+    assert exc.value.code == 1
+    err = capsys.readouterr().err
+    assert "ANTHROPIC_API_KEY" in err
+    assert err.startswith("Error:")
+
+
+@pytest.mark.usefixtures("clear_keys")
+def test_auto_selects_provider_by_priority(monkeypatch):
+    monkeypatch.setenv("ANTHROPIC_API_KEY", "x")
+    monkeypatch.setenv("GEMINI_API_KEY", "y")
+    provider, model = determine_provider_and_model(_args())
+    assert provider == "anthropic"
+    assert model == "claude-4-6-sonnet"
+
+
+@pytest.mark.usefixtures("clear_keys")
+def test_explicit_model_is_preserved(monkeypatch):
+    monkeypatch.setenv("OPENAI_API_KEY", "x")
+    provider, model = determine_provider_and_model(_args(model="custom-model"))
+    assert provider == "openai"
+    assert model == "custom-model"