diff --git a/crates/fidc-core/src/factor_events.rs b/crates/fidc-core/src/factor_events.rs
index 5844c0a..d841eb6 100644
--- a/crates/fidc-core/src/factor_events.rs
+++ b/crates/fidc-core/src/factor_events.rs
@@ -178,11 +178,11 @@ pub fn catalog() -> Value {
     let indicators: Vec<Value> = abstract_api::funcs().map(|f| json!({
         "name":f.name, "group":format!("{:?}",f.group), "description":f.hint,
         "inputs":f.inputs.iter().map(|p|json!({"name":p.param_name,"kind":format!("{:?}",p.kind),"flags":p.flags.0})).collect::<Vec<_>>(),
-        "parameters":f.opt_inputs.iter().map(|p|json!({"name":p.param_name,"label":p.display_name,"description":p.hint,"domain":format!("{:?}",p.kind)})).collect::<Vec<_>>(),
+        "parameters":f.opt_inputs.iter().map(|p|json!({"name":p.param_name,"label":p.display_name,"description":p.hint,"domain":parameter_domain(p.kind)})).collect::<Vec<_>>(),
         "outputs":f.outputs.iter().enumerate().map(|(i,p)|json!({"index":i,"name":p.param_name,"kind":format!("{:?}",p.kind)})).collect::<Vec<_>>(),
         "unstable_period":format!("{:?}",f.unst_id), "production_eligible":false,
     })).collect();
-    json!({"contract":CONTRACT,"expression_kernel_sha256":implementation_sha256,"library":{"name":"TA-Lib native Rust","revision":TA_REV,"license":"BSD-3-Clause"},
+    json!({"contract":CONTRACT,"parameter_domain_contract":"fidc.indicator-parameter-domain/v1","expression_kernel_sha256":implementation_sha256,"library":{"name":"TA-Lib native Rust","revision":TA_REV,"license":"BSD-3-Clause"},
         "execution_context_contract":crate::pattern_context::CONTRACT,
         "execution_context_fields":crate::pattern_context::CONTEXT_FIELDS,
         "market_event_context_contract":crate::market_event_context::CONTRACT,
@@ -196,6 +196,26 @@ pub fn catalog() -> Value {
         "minute_execution":"strictly_after_completed_bar","cross_section":"requires_separate_complete_universe_contract"}})
 }
 
+fn parameter_domain(kind: OptInputType) -> Value {
+    match kind {
+        OptInputType::IntegerRange { min, max, default, .. } => json!({
+            "value_type":"integer", "minimum":min, "maximum":max, "default":default,
+        }),
+        OptInputType::RealRange { min, max, default, precision, .. } => json!({
+            "value_type":"number", "minimum":min, "maximum":max,
+            "default":default, "display_precision":precision,
+        }),
+        OptInputType::IntegerList { values, default } => json!({
+            "value_type":"integer", "default":default,
+            "choices":values.iter().map(|(value,label)|json!({"value":value,"label":label})).collect::<Vec<_>>(),
+        }),
+        OptInputType::RealList { values, default } => json!({
+            "value_type":"number", "default":default,
+            "choices":values.iter().map(|(value,label)|json!({"value":value,"label":label})).collect::<Vec<_>>(),
+        }),
+    }
+}
+
 impl Frame {
     pub fn validate(&self) -> Result<(), String> {
         let n = self.timestamps.len();
@@ -960,6 +980,46 @@ fn operator(
 #[cfg(test)]
 mod tests {
     use super::*;
+
+    #[test]
+    fn every_parameter_domain_is_structured_and_matches_native_defaults() {
+        for function in abstract_api::funcs() {
+            let handle = abstract_api::get_func_handle(function.name).unwrap();
+            let core = Core::new();
+            let mut call = handle.new_call(&core);
+            for (index, parameter) in function.opt_inputs.iter().enumerate() {
+                let domain = parameter_domain(parameter.kind);
+                let default = domain["default"].as_f64().unwrap();
+                assert!(default.is_finite(), "{} {}", function.name, parameter.param_name);
+                if let Some(choices) = domain.get("choices") {
+                    assert!(choices.as_array().unwrap().iter().any(|v| v["value"].as_f64() == Some(default)));
+                } else {
+                    assert!(default >= domain["minimum"].as_f64().unwrap());
+                    assert!(default <= domain["maximum"].as_f64().unwrap());
+                }
+                if domain["value_type"] == "integer" {
+                    assert_eq!(default.fract(), 0.0);
+                    call.set_opt(index, default as i32).unwrap();
+                } else {
+                    call.set_opt(index, default).unwrap();
+                }
+            }
+            assert!(call.lookback().is_ok(), "{}", function.name);
+        }
+    }
+
+    #[test]
+    fn parameter_domains_keep_enumeration_labels_without_debug_string_parsing() {
+        let catalog = catalog();
+        assert_eq!(catalog["parameter_domain_contract"], "fidc.indicator-parameter-domain/v1");
+        let indicators = catalog["indicators"].as_array().unwrap();
+        let rsi = indicators.iter().find(|v| v["name"] == "RSI").unwrap();
+        assert_eq!(rsi["parameters"][0]["domain"]["minimum"], 2);
+        let stoch = indicators.iter().find(|v| v["name"] == "STOCH").unwrap();
+        let ma_type = stoch["parameters"].as_array().unwrap().iter().find(|p| p["name"] == "optInSlowK_MAType").unwrap();
+        assert!(ma_type["domain"]["choices"].as_array().unwrap().iter().any(|v| v["label"] == "EMA" && v["value"] == 1));
+    }
+
     fn frame(values: Vec<Option<f64>>) -> Frame {
         let start = DateTime::parse_from_rfc3339("2026-09-01T15:30:00+08:00").unwrap();
         let times = (0..values.len())