Fix alert threshold double_value with terraform engine (#4615)

## Summary
- The TF schema codegen maps `cty.Number` to Go `int` by default. The
alert `double_value` field was not in the `float64` allowlist, so
fractional values like `1.3` were dropped during normalization, causing
terraform to fail with `"evaluation.threshold is provided but doesn't
contain any value"`.
- Add alert `double_value` paths to the float64 allowlist and update the
generated schema types from `int` to `float64`.

## Test plan
- [x] Unit test `TestConvertAlertWithThresholdDoubleValue` verifies
fractional `double_value` survives normalization
- [x] Updated existing `acceptance/bundle/resources/alerts/basic`
acceptance test to use fractional `double_value: 1.3` instead of integer
`2`

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: shreyas-goenka

acceptance/bundle/resources/alerts/basic/databricks.yml.tmpl

@@ -21,7 +21,7 @@ resources:
           name: "1"
         threshold:
           value:
-            double_value: 2
+            double_value: 1.3
       query_text: "select 2"
       schedule:
         pause_status: "UNPAUSED"

acceptance/bundle/resources/alerts/basic/output.txt

@@ -23,7 +23,7 @@ Deployment complete!
     },
     "threshold": {
       "value": {
-        "double_value": 2
+        "double_value": 1.3
       }
     }
   },

bundle/deploy/terraform/tfdyn/convert_alert_test.go

@@ -68,3 +68,41 @@ func TestConvertAlert(t *testing.T) {
 		},
 	}, out.Permissions["alert_test_alert"])
 }
+
+func TestConvertAlertWithThresholdDoubleValue(t *testing.T) {
+	src := resources.Alert{
+		AlertV2: sql.AlertV2{
+			DisplayName: "test_alert",
+			QueryText:   "SELECT 1",
+			WarehouseId: "test_warehouse_id",
+			Evaluation: sql.AlertV2Evaluation{
+				ComparisonOperator: "EQUAL",
+				Source: sql.AlertV2OperandColumn{
+					Name: "1",
+				},
+				Threshold: &sql.AlertV2Operand{
+					Value: &sql.AlertV2OperandValue{
+						DoubleValue: 1.3,
+					},
+				},
+			},
+		},
+	}
+
+	vin, err := convert.FromTyped(src, dyn.NilValue)
+	require.NoError(t, err)
+
+	ctx := context.Background()
+	out := schema.NewResources()
+	err = alertConverter{}.Convert(ctx, "test_alert", vin, out)
+	require.NoError(t, err)
+
+	alert := out.AlertV2["test_alert"]
+	alertMap := alert.(map[string]any)
+	evaluation := alertMap["evaluation"].(map[string]any)
+	threshold := evaluation["threshold"].(map[string]any)
+	value := threshold["value"].(map[string]any)
+
+	// Assert the fractional double_value is preserved after normalization.
+	assert.InDelta(t, 1.3, value["double_value"], 0.0001)
+}

bundle/internal/tf/codegen/generator/walker.go

@@ -33,6 +33,9 @@ type walker struct {
 // that should be mapped to float64 instead of int for cty.Number types.
 // Generated from Terraform provider schema based on databricks-sdk-go types.
 var floatAttributePaths = map[string]bool{
+	// Alert thresholds - double_value fields hold fractional values (e.g., 1.3)
+	"databricks_alert_v2.evaluation.threshold.value.double_value": true,
+
 	// Postgres Service - autoscaling compute units support fractional values (e.g., 0.5 CU)
 	"databricks_postgres_endpoint.spec.autoscaling_limit_max_cu":                                      true,
 	"databricks_postgres_endpoint.spec.autoscaling_limit_min_cu":                                      true,