feat(fc3b): platforms.py — GS-6 registry (single source of truth)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_platforms_registry.py

@@ -0,0 +1,50 @@
+import re
+
+import pytest
+
+from backend.app.services.platforms import (
+    PLATFORMS,
+    PlatformInfo,
+    auth_type_for,
+    known_platform_keys,
+    to_dict,
+)
+
+
+def test_known_platform_keys_is_gs_six():
+    assert known_platform_keys() == frozenset({
+        "patreon", "subscribestar", "hentaifoundry",
+        "discord", "pixiv", "deviantart",
+    })
+
+
+def test_fanbox_not_in_registry():
+    # Sanity check — FC-3a added 'fanbox' by mistake; it's not a GS platform.
+    assert "fanbox" not in PLATFORMS
+
+
+def test_auth_type_for_known_and_unknown():
+    assert auth_type_for("patreon") == "cookies"
+    assert auth_type_for("discord") == "token"
+    assert auth_type_for("nope") is None
+
+
+def test_each_platform_has_required_fields():
+    for key, info in PLATFORMS.items():
+        assert isinstance(info, PlatformInfo)
+        assert info.key == key
+        assert info.name
+        assert info.description
+        assert info.auth_type in ("cookies", "token")
+        assert isinstance(info.requires_auth, bool)
+        re.compile(info.url_pattern)  # valid regex
+        assert info.url_examples
+        assert isinstance(info.default_config, dict)
+
+
+def test_to_dict_round_trip():
+    d = to_dict(PLATFORMS["patreon"])
+    assert d["key"] == "patreon"
+    assert d["auth_type"] == "cookies"
+    assert d["default_config"]["sleep"] == 3.0
+    assert "url_examples" in d