fix(auth): show subscription setup errors

Preserve subscription-auth failures instead of rewriting them as missing API keys, and point Claude/Codex subscription users at the correct login and provider commands.

Fixes #254

src/openharness/ui/runtime.py

@@ -198,13 +198,8 @@ def _resolve_api_client_from_settings(settings) -> SupportsStreamingMessages:
     def _safe_resolve_auth():
         try:
             return settings.resolve_auth()
-        except (ValueError, Exception):
-            print(
-                "Error: No API key configured.\n"
-                "  Run `oh auth login` to set up authentication, or set the\n"
-                "  ANTHROPIC_API_KEY (or OPENAI_API_KEY) environment variable.",
-                file=sys.stderr,
-            )
+        except Exception as exc:
+            _print_auth_resolution_error(settings, exc)
             raise SystemExit(1)
 
     if settings.api_format == "copilot":
@@ -243,6 +238,39 @@ def _resolve_api_client_from_settings(settings) -> SupportsStreamingMessages:
     )
 
 
+def _print_auth_resolution_error(settings, exc: Exception) -> None:
+    """Render auth failures without collapsing subscription errors into API-key advice."""
+    try:
+        profile_name, profile = settings.resolve_profile()
+        auth_source = (getattr(profile, "auth_source", "") or "").strip()
+    except Exception:
+        profile_name = ""
+        auth_source = ""
+
+    message = str(exc).strip() or exc.__class__.__name__
+    if auth_source in {"claude_subscription", "codex_subscription"}:
+        login_command = "claude-login" if auth_source == "claude_subscription" else "codex-login"
+        provider_name = profile_name or (
+            "claude-subscription" if auth_source == "claude_subscription" else "codex"
+        )
+        print(
+            f"Error: {message}\n"
+            f"  This profile uses subscription auth, not an API key.\n"
+            f"  Run `oh auth {login_command}` to bind the local CLI session, then\n"
+            f"  run `oh provider use {provider_name}` to activate it.",
+            file=sys.stderr,
+        )
+        return
+
+    print(
+        "Error: No API key configured.\n"
+        f"  {message}\n"
+        "  Run `oh auth login` to set up authentication, or set the\n"
+        "  ANTHROPIC_API_KEY (or OPENAI_API_KEY) environment variable.",
+        file=sys.stderr,
+    )
+
+
 async def build_runtime(
     *,
     prompt: str | None = None,

tests/test_ui/test_runtime_api_key.py

@@ -31,3 +31,19 @@ async def test_build_runtime_exits_cleanly_for_openai_format(monkeypatch):
 
     with pytest.raises(SystemExit, match="1"):
         await build_runtime(active_profile="openai-compatible", api_format="openai")
+
+
+@pytest.mark.asyncio
+async def test_build_runtime_reports_subscription_auth_setup(monkeypatch, tmp_path, capsys):
+    """Subscription profiles should not be reported as missing API keys."""
+    monkeypatch.setenv("OPENHARNESS_CONFIG_DIR", str(tmp_path / "config"))
+    monkeypatch.delenv("ANTHROPIC_AUTH_TOKEN", raising=False)
+
+    with pytest.raises(SystemExit, match="1"):
+        await build_runtime(active_profile="claude-subscription")
+
+    captured = capsys.readouterr()
+    assert "subscription auth, not an API key" in captured.err
+    assert "oh auth claude-login" in captured.err
+    assert "oh provider use claude-subscription" in captured.err
+    assert "No API key configured" not in captured.err