feat: apply contract defaults to sources

src/sqlbuild/compiler/compile/_helpers/attachment/sources.py

@@ -61,6 +61,7 @@ def build_source_inputs(
     source_inputs: list[CompileSourceInput] = []
     sql_validation_enabled: bool = effective_settings.sql_analysis and not no_sql_validation
     resolver: DeclarationScopeResolver | None = declaration_expansion.resolver
+    default_contract: str | None = discovered_inputs.project_config.defaults.contract
     reuse_file_scope: bool = (
         resolver is not None
         and not any(
@@ -76,6 +77,12 @@ def build_source_inputs(
     for source_file in discovered_inputs.source_files:
         source_entry: SourceEntry
         for raw_source_entry in source_file.source_entries:
+            effective_source_entry: SourceEntry = raw_source_entry
+            if raw_source_entry.contract is None and default_contract is not None:
+                effective_source_entry = replace(
+                    raw_source_entry,
+                    contract=default_contract,
+                )
             source_resource: ResourceIdentity = ResourceIdentity(
                 ResourceKind.SOURCE, raw_source_entry.name
             )
@@ -95,7 +102,7 @@ def build_source_inputs(
                 if reuse_file_scope:
                     declarations_by_file[source_file.file_path] = scoped_declarations
             source_entry, usages = expand_source_entry_templates(
-                source_entry=raw_source_entry,
+                source_entry=effective_source_entry,
                 file_path=source_file.file_path,
                 effective_vars=effective_vars,
                 loaded_macros=loaded_macros,

tests/integration/src/sqlbuild/cli/commands/main/test_rules.py

@@ -270,14 +270,14 @@ def test_given_contract_rules_when_compiling_then_contract_is_enforced_typed_and
 ) -> None:
     (tmp_path / "sqlbuild_project.toml").write_text(
         'name = "orders"\nadapter = "duckdb"\n\n[rules]\n'
-        'select = ["SQBRCONTRACT101", "SQBRCONTRACT105", "SQBRCONTRACT106"]\n',
+        'select = ["SQBRCONTRACT101", "SQBRCONTRACT105", "SQBRCONTRACT106"]\n\n'
+        '[defaults]\ncontract = "enforced"\n',
         encoding="utf-8",
     )
     model: Path = tmp_path / "models" / "orders.sql"
     model.parent.mkdir()
     model.write_text(
         "MODEL (\n"
-        "  contract enforced,\n"
         f"  columns ({test_case.columns_sql}),\n"
         ");\n\n"
         "SELECT CAST(1 AS INTEGER) AS order_id, CAST('ready' AS VARCHAR) AS status\n",

tests/integration/src/sqlbuild/compiler/pipeline/_test_types.py

@@ -49,6 +49,15 @@ class SemanticBindingIntegrationTestCase:
     expected_exit_code: int
 
 
+@dataclass(frozen=True)
+class SourceContractDefaultIntegrationTestCase:
+    description: str
+    source_contract_yaml: str
+    expected_exit_code: int
+    expected_output_fragment: str
+    expected_absent_output_fragment: str
+
+
 @dataclass(frozen=True)
 class ExpectedModelEntry:
     description: str

tests/integration/src/sqlbuild/compiler/pipeline/test_semantic_binding.py

@@ -12,6 +12,7 @@
 from tests.integration.src.sqlbuild.compiler.pipeline._test_types import (
     SemanticBindingClauseIntegrationTestCase,
     SemanticBindingIntegrationTestCase,
+    SourceContractDefaultIntegrationTestCase,
 )
 from tests.integration.src.sqlbuild.compiler.pipeline.helpers import write_semantic_binding_project
 
@@ -198,47 +199,59 @@ def test_given_partial_upstream_when_column_absence_is_unproven_then_compile_suc
 @pytest.mark.parametrize(
     "test_case",
     [
-        SemanticBindingIntegrationTestCase(
-            description="given enforced source contract when column is missing then compile fails",
+        SourceContractDefaultIntegrationTestCase(
+            description="given default enforced source contract when column is missing then compile fails",
+            source_contract_yaml="",
             expected_exit_code=1,
-        )
+            expected_output_fragment="error[B002]: Unknown column 'missing' in table 'raw_orders'",
+            expected_absent_output_fragment="0 errors, 0 warnings",
+        ),
+        SourceContractDefaultIntegrationTestCase(
+            description="given explicit open source contract when default is enforced then compile succeeds",
+            source_contract_yaml="    contract: none\n",
+            expected_exit_code=0,
+            expected_output_fragment="0 errors, 0 warnings",
+            expected_absent_output_fragment="error[B002]",
+        ),
     ],
     ids=lambda case: case.description,
 )
-def test_given_enforced_source_contract_when_column_is_missing_then_compile_fails(
-    test_case: SemanticBindingIntegrationTestCase,
+def test_given_source_contract_default_when_compiling_then_effective_policy_controls_authority(
+    test_case: SourceContractDefaultIntegrationTestCase,
     tmp_path: Path,
     capsys: pytest.CaptureFixture[str],
 ) -> None:
     _ = (tmp_path / "sqlbuild_project.toml").write_text(
-        'name = "semantic_binding"\nadapter = "duckdb"\n', encoding="utf-8"
+        'name = "semantic_binding"\nadapter = "duckdb"\n\n[defaults]\ncontract = "enforced"\n',
+        encoding="utf-8",
     )
     sources_dir: Path = tmp_path / "sources"
     models_dir: Path = tmp_path / "models"
     sources_dir.mkdir()
     models_dir.mkdir()
     _ = (sources_dir / "raw.yml").write_text(
-        """sources:
+        f"""sources:
   - name: raw_orders
     schema: raw
     table: orders
-    contract: enforced
-    columns:
+{test_case.source_contract_yaml}    columns:
       - name: id
         type: INTEGER
 """,
         encoding="utf-8",
     )
     _ = (models_dir / "downstream.sql").write_text(
-        'MODEL (materialized view);\nSELECT missing FROM __source("raw_orders")\n',
+        "MODEL (materialized view, columns (missing (type INTEGER)));\n"
+        'SELECT CAST(missing AS INTEGER) AS missing FROM __source("raw_orders")\n',
         encoding="utf-8",
     )
 
     exit_code: int = main(["--no-color", "--project-dir", str(tmp_path), "compile", "--no-cache"])
 
     output: str = capsys.readouterr().out
     assert exit_code == test_case.expected_exit_code
-    assert "error[B002]: Unknown column 'missing' in table 'raw_orders'" in output
+    assert test_case.expected_output_fragment in output
+    assert test_case.expected_absent_output_fragment not in output
 
 
 @pytest.mark.parametrize(