feat(dialect): require version adaptation before using Postgres dialect (#37)

* feat(dialect): require version adaptation before using Postgres dialect

PostgresDialect now defaults to version=None, requiring
introspect_and_adapt() or explicit version before version-dependent
features can be used. This prevents silent SQL errors from incorrect
version assumptions.

- Change PostgresDialect.__init__ default version to None
- Remove hardcoded (9, 6, 0) from backend dialect construction
- Update tests to use explicit version (13, 0, 0)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

* chore: add changelog fragment for PR #37

---------

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

Author: vistart

changelog.d/37.changed.md

@@ -0,0 +1 @@
+Changed PostgresDialect to default to version=None instead of fixed version, requiring introspect_and_adapt() or explicit version before version-dependent features can be used.

src/rhosocial/activerecord/backend/impl/postgres/backend/async_backend.py

@@ -138,8 +138,8 @@ def __init__(self, **kwargs):
         super().__init__(**kwargs)
 
         # Initialize PostgreSQL-specific components
-        # Use default version (9.6.0) - actual version detected via introspect_and_adapt()
-        self._dialect = PostgresDialect((9, 6, 0))
+        # Version is None until introspect_and_adapt() is called
+        self._dialect = PostgresDialect()
 
         # Register PostgreSQL-specific type adapters (same as sync backend)
         # Note: XML adapter is NOT registered by default due to potential conflicts.

src/rhosocial/activerecord/backend/impl/postgres/backend/sync.py

@@ -138,8 +138,8 @@ def __init__(self, **kwargs):
         super().__init__(**kwargs)
 
         # Initialize PostgreSQL-specific components
-        # Use default version (9.6.0) - actual version detected via introspect_and_adapt()
-        self._dialect = PostgresDialect((9, 6, 0))
+        # Version is None until introspect_and_adapt() is called
+        self._dialect = PostgresDialect()
 
         # Register PostgreSQL-specific type adapters (same as async backend)
         # Note: XML adapter is NOT registered by default due to potential conflicts.

src/rhosocial/activerecord/backend/impl/postgres/dialect.py

@@ -427,15 +427,19 @@ class PostgresDialect(
     Use introspect_and_adapt() to detect installed extensions automatically.
     """
 
-    def __init__(self, version: Tuple[int, int, int] = (13, 0, 0)):
+    def __init__(self, version: Optional[Tuple[int, int, int]] = None):
         """
         Initialize PostgreSQL dialect with specific version.
 
         Args:
-            version: PostgreSQL version tuple (major, minor, patch)
+            version: PostgreSQL version tuple (major, minor, patch).
+                If None, the dialect must be adapted via
+                backend.introspect_and_adapt() before version-dependent
+                features can be used.
         """
-        self.version = version
         super().__init__()
+        if version is not None:
+            self.version = version
 
     @staticmethod
     def _validate_data_type(data_type: str) -> bool:

tests/rhosocial/activerecord_postgres_test/feature/backend/test_dialect_function_support.py

@@ -15,21 +15,21 @@ class TestPostgreSQLFunctionSupportBasic:
 
     def test_supports_functions_returns_dict(self):
         """Test that supports_functions returns a dictionary."""
-        dialect = PostgresDialect()
+        dialect = PostgresDialect((13, 0, 0))
         result = dialect.supports_functions()
         assert isinstance(result, dict)
         assert len(result) > 0
 
     def test_supports_functions_all_values_are_support_info(self):
         """Test that all values in the returned dict are FunctionSupportInfo."""
-        dialect = PostgresDialect()
+        dialect = PostgresDialect((13, 0, 0))
         result = dialect.supports_functions()
         for func_name, info in result.items():
             assert isinstance(info, FunctionSupportInfo), f"Value for {func_name} is not FunctionSupportInfo"
 
     def test_core_functions_always_supported(self):
         """Test that core functions are marked as supported."""
-        dialect = PostgresDialect()
+        dialect = PostgresDialect((13, 0, 0))
         result = dialect.supports_functions()
         core_functions = ["count", "sum_", "avg", "min_", "max_", "coalesce", "nullif"]
         for func in core_functions:
@@ -231,7 +231,7 @@ def test_macaddr8_set7bit_requires_pg_10(self):
 
     def test_always_available_functions(self):
         """Test functions that are available in all PostgreSQL versions."""
-        dialect = PostgresDialect()
+        dialect = PostgresDialect((13, 0, 0))
         result = dialect.supports_functions()
 
         always_available = [
@@ -249,7 +249,7 @@ class TestPostgreSQLFunctionSupportPrivateMethod:
 
     def test_unknown_function_returns_true(self):
         """Test that unknown functions return True (no restriction)."""
-        dialect = PostgresDialect()
+        dialect = PostgresDialect((13, 0, 0))
         result = dialect._is_postgres_function_supported("unknown_function_xyz")
         assert result is True
 
@@ -277,7 +277,7 @@ class TestPostgreSQLFunctionSupportIntegration:
 
     def test_function_dict_contains_both_core_and_backend_functions(self):
         """Test that the result contains both core and PostgreSQL-specific functions."""
-        dialect = PostgresDialect()
+        dialect = PostgresDialect((13, 0, 0))
         result = dialect.supports_functions()
 
         assert any(func in result for func in ["count", "sum", "avg"])

tests/rhosocial/activerecord_postgres_test/feature/backend/test_postgres_dialect_security.py

@@ -23,7 +23,7 @@
 @pytest.fixture
 def dialect():
     """Create a PostgreSQL test dialect."""
-    return PostgresDialect()
+    return PostgresDialect((13, 0, 0))
 
 
 def test_postgres_escape_sql_string(dialect):