diff --git a/moli-renderer-v8/src/abort_signal_route.rs b/moli-renderer-v8/src/abort_signal_route.rs
index f9e463590b..64976c071e 100644
--- a/moli-renderer-v8/src/abort_signal_route.rs
+++ b/moli-renderer-v8/src/abort_signal_route.rs
@@ -8,7 +8,7 @@
 //! registration back to the owning store.
 
 use crate::context_bootstrap::context_host_ptr_from_global_bridge;
-use crate::util::{throw_type_error, v8str};
+use crate::webidl;
 
 #[derive(Clone, Copy)]
 enum AbortSignalOwner {
@@ -136,39 +136,30 @@ impl<'s> ResolvedAbortSignal<'s> {
     }
 }
 
-/// Parses the `signal` member of `AddEventListenerOptions`.
-///
-/// The outer `Option` distinguishes abrupt conversion from an absent member;
-/// the inner `Option` distinguishes no signal from a validated Window/worker
-/// signal capability.
+/// Converts the final AddEventListenerOptions member after capture/once/passive.
+/// A dictionary uses Get, not HasProperty: Proxy traps and inherited getters
+/// must run exactly once, and their original exceptions must escape unchanged.
 pub(crate) fn event_listener_signal_from_options_value<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     value: v8::Local<'s, v8::Value>,
-) -> Option<Option<ResolvedAbortSignal<'s>>> {
-    if value.is_null_or_undefined() || !value.is_object() {
-        return Some(None);
-    }
+) -> Result<Option<ResolvedAbortSignal<'s>>, webidl::WebIdlError> {
     let Ok(options) = v8::Local::<v8::Object>::try_from(value) else {
-        return Some(None);
+        return Ok(None);
+    };
+    let context = webidl::Context::member("AddEventListenerOptions", "signal");
+    let Some(signal_value) = webidl::property_result(scope, options, "signal", context)? else {
+        return Ok(None);
     };
-    let signal_key = v8str(scope, "signal");
-    let signal_value = options.get(scope, signal_key.into())?;
     if signal_value.is_undefined() {
-        return Some(None);
+        return Ok(None);
     }
-    let Ok(signal) = v8::Local::<v8::Object>::try_from(signal_value) else {
-        throw_type_error(
-            scope,
-            "Failed to execute 'addEventListener': options.signal must be an AbortSignal.",
-        );
-        return None;
-    };
-    let Some(signal) = ResolvedAbortSignal::resolve(scope, signal) else {
-        throw_type_error(
-            scope,
-            "Failed to execute 'addEventListener': options.signal must be an AbortSignal.",
-        );
-        return None;
-    };
-    Some(Some(signal))
+    let signal = v8::Local::<v8::Object>::try_from(signal_value)
+        .ok()
+        .and_then(|signal| ResolvedAbortSignal::resolve(scope, signal))
+        .ok_or_else(|| {
+            webidl::WebIdlError::custom_message(
+                "Failed to execute 'addEventListener': options.signal must be an AbortSignal.",
+            )
+        })?;
+    Ok(Some(signal))
 }
diff --git a/moli-renderer-v8/src/event_listener_args.rs b/moli-renderer-v8/src/event_listener_args.rs
index e0ad3375eb..5a801a4ee4 100644
--- a/moli-renderer-v8/src/event_listener_args.rs
+++ b/moli-renderer-v8/src/event_listener_args.rs
@@ -41,7 +41,7 @@ pub(crate) struct RemoveEventListenerArgs {
     pub(crate) event_type: String,
     #[webidl(required, converter = "callback_interface", nullable)]
     pub(crate) listener: Option<webidl::WebIdlCallbackInterface>,
-    #[webidl(with = remove_event_listener_options)]
+    #[webidl(with = webidl::event_listener_options)]
     pub(crate) options: webidl::EventListenerOptions,
 }
 
@@ -59,35 +59,6 @@ fn add_event_listener_options<'s>(
     // lexical order. Finish conversion even when the callback is null.
     let value = args.get(index);
     let options = webidl::add_event_listener_options_value(scope, value)?;
-    let signal = event_listener_signal_from_options_value(scope, value).ok_or_else(|| {
-        webidl::WebIdlError::pending_exception(webidl::Context::member(
-            "AddEventListenerOptions",
-            "signal",
-        ))
-    })?;
+    let signal = event_listener_signal_from_options_value(scope, value)?;
     Ok(AddEventListenerOptions { options, signal })
 }
-
-#[derive(webidl::WebIdlDictionary)]
-#[webidl(prefix = "EventListenerOptions")]
-struct RemoveEventListenerOptions {
-    #[webidl(default = false)]
-    capture: bool,
-}
-
-fn remove_event_listener_options<'s>(
-    scope: &mut v8::PinScope<'s, '_>,
-    args: &v8::FunctionCallbackArguments<'s>,
-    index: i32,
-) -> Result<webidl::EventListenerOptions, webidl::WebIdlError> {
-    let value = args.get(index);
-    let capture = if let Ok(object) = v8::Local::<v8::Object>::try_from(value) {
-        webidl::parse_dictionary_object::<RemoveEventListenerOptions>(scope, object)?.capture
-    } else {
-        value.boolean_value(scope)
-    };
-    Ok(webidl::EventListenerOptions {
-        capture,
-        ..webidl::EventListenerOptions::default()
-    })
-}
diff --git a/moli-renderer-v8/src/script_vm/tests/browser_api/event_listener_options.rs b/moli-renderer-v8/src/script_vm/tests/browser_api/event_listener_options.rs
new file mode 100644
index 0000000000..c51086d9ab
--- /dev/null
+++ b/moli-renderer-v8/src/script_vm/tests/browser_api/event_listener_options.rs
@@ -0,0 +1,254 @@
+use super::service_worker_drain::drain_service_worker_test_turn;
+use super::*;
+
+const OPTIONS_PROBE: &str = r#"function checkOptions(targets) {
+ const rows=[];let serial=0;
+ for(const [targetName,create] of targets) for(const method of ['addEventListener','removeEventListener'])
+ for(const callbackKind of ['function','null','primitive']) for(const fail of ['none','capture','once','passive','signal']) {
+  const [target,eventType,cleanup]=create(++serial);
+  const trace=[],marker={};let count=0,error=null;
+  const listener=()=>count++;
+  const callback=callbackKind==='function'?listener:callbackKind==='null'?null:42;
+  if(method==='removeEventListener')target.addEventListener(eventType,listener);
+  const type={toString(){trace.push('type');return eventType;}};
+  const options=new Proxy({}, {
+   has(_,name){trace.push('has:'+name);return true;},
+   get(_,name){trace.push(String(name));if(name===fail)throw marker;return name==='signal'?undefined:false;}
+  });
+  try{target[method](type,callback,options);}catch(e){error=e===marker?'marker':e.name;}
+  target.dispatchEvent(new Event(eventType));
+  target.removeEventListener(eventType,listener);
+  rows.push({target:targetName,method,callback:callbackKind,fail,trace,error,count});
+  if(cleanup)cleanup();
+ }
+ return rows;
+}
+"#;
+
+const PORT_PROBE: &str = r#"async function checkPortOptions() {
+ const targets=[['MessagePort',()=>{const channel=new MessageChannel();return [channel.port1,'message',()=>{channel.port1.close();channel.port2.close();},()=>channel.port2.postMessage('probe')];}]];
+ const rows=[];let serial=0;
+ for(const [targetName,create] of targets) for(const method of ['addEventListener','removeEventListener'])
+ for(const callbackKind of ['function','null','primitive']) for(const fail of ['none','capture','once','passive','signal']) {
+  const [target,eventType,cleanup,send]=create(++serial);
+  const trace=[],marker={};let count=0,error=null;
+  const listener=()=>count++;
+  const callback=callbackKind==='function'?listener:callbackKind==='null'?null:42;
+  if(method==='removeEventListener')target.addEventListener(eventType,listener);
+  const type={toString(){trace.push('type');return eventType;}};
+  const options=new Proxy({}, {
+   has(_,name){trace.push('has:'+name);return true;},
+   get(_,name){trace.push(String(name));if(name===fail)throw marker;return name==='signal'?undefined:false;}
+  });
+  try{target[method](type,callback,options);}catch(e){error=e===marker?'marker':e.name;}
+  await new Promise(resolve=>{target.onmessage=resolve;target.start();send();});
+  target.removeEventListener(eventType,listener);
+  rows.push({target:targetName,method,callback:callbackKind,fail,trace,error,count});
+  if(cleanup)cleanup();
+ }
+ return rows;
+}
+"#;
+
+const PAGE_PROBE: &str = r#"(() => {
+ const frame=document.body.appendChild(document.createElement('iframe'));
+ const rows=checkOptions([
+ ['Window',n=>[window,'options-'+n]],
+ ['child Window',n=>[frame.contentWindow,'options-'+n]],
+ ['Document',n=>[document,'options-'+n]],
+ ['Element',n=>[document.createElement('div'),'options-'+n]],
+ ['EventTarget',n=>[new EventTarget(),'options-'+n]],
+ ['FileReader',n=>[new FileReader(),'options-'+n]],
+ ['AbortSignal',()=>[new AbortController().signal,'abort']]
+ ]);frame.remove();return rows;
+})()"#;
+
+const WORKER_TARGETS: &str = r#"checkOptions([
+ ['WorkerGlobalScope',n=>[self,'options-'+n]],
+ ['EventTarget',n=>[new EventTarget(),'options-'+n]],
+ ['FileReader',n=>[new FileReader(),'options-'+n]],
+ ['AbortSignal',()=>[new AbortController().signal,'abort']]
+])"#;
+
+const SIGNAL_PROBE: &str = r#"(() => {
+ const frame=document.body.appendChild(document.createElement('iframe'));
+ const child=frame.contentWindow;
+ const channel=new MessageChannel();
+ const targets=[window,child,document,document.createElement('div'),new EventTarget(),new FileReader(),new AbortController().signal,channel.port1];
+ const localSignal=new AbortController().signal,childSignal=new child.AbortController().signal;
+ const revoked=Proxy.revocable(localSignal,{});revoked.revoke();
+ const signals=[['undefined',undefined],['null',null],['number',1],['object',{}],['forged',Object.create(AbortSignal.prototype)],['proxy',new Proxy(localSignal,{})],['revoked',revoked.proxy],['local',localSignal],['child',childSignal]];
+ const rows=[];
+ for(let index=0;index<targets.length;index++)for(const method of ['addEventListener','removeEventListener'])for(const [kind,signal]of signals){
+  const trace=[];let error=null,realm=null;
+  const options=new Proxy({}, {get(_,key){trace.push(String(key));return key==='signal'?signal:false;},has(){throw new Error('must not call HasProperty');}});
+  try{targets[index][method]('probe',null,options);}catch(e){error=e.name;realm=e instanceof (index===1?child:window).TypeError;}
+  rows.push({index,method,kind,trace,error,realm});
+ }
+ channel.port1.close();channel.port2.close();frame.remove();return rows;
+})()"#;
+
+fn assert_option_rows(value: &serde_json::Value, expected_rows: usize) {
+    let rows = value.as_array().expect("options probe must return rows");
+    assert_eq!(rows.len(), expected_rows);
+    for row in rows {
+        let add = row["method"] == "addEventListener";
+        let primitive = row["callback"] == "primitive";
+        let callable = row["callback"] == "function";
+        let fail = row["fail"].as_str().unwrap();
+        let members: &[&str] = if add {
+            &["capture", "once", "passive", "signal"]
+        } else {
+            &["capture"]
+        };
+        let mut trace = vec!["type"];
+        let mut error = None;
+        if primitive {
+            error = Some("TypeError");
+        } else {
+            for member in members {
+                trace.push(member);
+                if *member == fail {
+                    error = Some("marker");
+                    break;
+                }
+            }
+        }
+        let count = if add {
+            usize::from(callable && error.is_none())
+        } else {
+            usize::from(!callable || error.is_some())
+        };
+        assert_eq!(row["trace"], serde_json::json!(trace), "{row}");
+        assert_eq!(row["error"], serde_json::json!(error), "{row}");
+        assert_eq!(row["count"], serde_json::json!(count), "{row}");
+    }
+}
+
+#[test]
+fn event_listener_options_convert_in_order_and_stop_before_mutation() {
+    let mut vm = new_parsed_test_vm(
+        "https://event-listener-options.test/",
+        "<!doctype html><html><body></body></html>",
+    );
+    let value = vm
+        .eval(&format!("{OPTIONS_PROBE}\nJSON.stringify({PAGE_PROBE})"))
+        .unwrap();
+    assert_option_rows(&serde_json::from_str(&value).unwrap(), 210);
+}
+
+#[test]
+fn event_listener_options_validate_signal_even_for_null_callbacks() {
+    let mut vm = new_parsed_test_vm(
+        "https://event-listener-signal-conversion.test/",
+        "<!doctype html><html><body></body></html>",
+    );
+    let value = vm.eval(&format!("JSON.stringify({SIGNAL_PROBE})")).unwrap();
+    let rows: serde_json::Value = serde_json::from_str(&value).unwrap();
+    let rows = rows.as_array().unwrap();
+    assert_eq!(rows.len(), 144);
+    for row in rows {
+        let add = row["method"] == "addEventListener";
+        let valid = matches!(
+            row["kind"].as_str().unwrap(),
+            "undefined" | "local" | "child"
+        );
+        let expected = if add && !valid {
+            serde_json::json!("TypeError")
+        } else {
+            serde_json::Value::Null
+        };
+        assert_eq!(row["error"], expected, "{row}");
+        assert_eq!(
+            row["realm"],
+            if expected.is_null() {
+                serde_json::Value::Null
+            } else {
+                serde_json::json!(true)
+            },
+            "{row}"
+        );
+        assert_eq!(
+            row["trace"],
+            if add {
+                serde_json::json!(["capture", "once", "passive", "signal"])
+            } else {
+                serde_json::json!(["capture"])
+            },
+            "{row}"
+        );
+    }
+}
+
+#[tokio::test]
+async fn worker_event_listener_options_share_conversion_and_exception_semantics() {
+    for shared in [false, true] {
+        let loader = ResourceRequestClient::new(&moli_fetch::FetchConfig::default()).unwrap();
+        let (mut vm, browser_context_runtime) =
+            new_service_worker_page_test_vm_with_loader_and_browser_context_runtime(
+                "https://worker-listener-options.test/",
+                &loader,
+            );
+        let worker_source = if shared {
+            format!(
+                "{OPTIONS_PROBE}\n{PORT_PROBE}\nonconnect=async e=>e.ports[0].postMessage({{options:{WORKER_TARGETS},ports:await checkPortOptions()}});"
+            )
+        } else {
+            format!(
+                "{OPTIONS_PROBE}\n{PORT_PROBE}\n(async()=>postMessage({{options:{WORKER_TARGETS},ports:await checkPortOptions()}}))();"
+            )
+        };
+        let worker_source = serde_json::to_string(&worker_source).unwrap();
+        let constructor = if shared { "SharedWorker" } else { "Worker" };
+        let port = if shared { "worker.port" } else { "worker" };
+        let cleanup = if shared {
+            "port.close()"
+        } else {
+            "worker.terminate()"
+        };
+        vm.eval(&format!(r#"
+            const url=URL.createObjectURL(new Blob([{worker_source}],{{type:'text/javascript'}}));
+            const worker=new {constructor}(url),port={port};
+            port.onmessage=e=>{{globalThis.optionsResult=e.data;{cleanup};URL.revokeObjectURL(url);}};
+            worker.onerror=e=>{{globalThis.optionsResult=String(e.message);}};
+        "#)).unwrap();
+        tokio::time::timeout(std::time::Duration::from_secs(10), async {
+            while vm.eval("globalThis.optionsResult !== undefined").unwrap() != "true" {
+                browser_context_runtime.drain_shared_worker_service_lane();
+                drain_service_worker_test_turn(&mut vm, &browser_context_runtime, &loader).await;
+            }
+        })
+        .await
+        .expect("worker options probe should settle");
+        let value = vm.eval("JSON.stringify(globalThis.optionsResult)").unwrap();
+        let value: serde_json::Value = serde_json::from_str(&value).unwrap();
+        assert_option_rows(&value["options"], 120);
+        assert_option_rows(&value["ports"], 30);
+    }
+}
+
+#[tokio::test]
+async fn message_port_options_errors_preserve_actual_message_listeners() {
+    let loader = ResourceRequestClient::new(&moli_fetch::FetchConfig::default()).unwrap();
+    let (mut vm, browser_context_runtime) =
+        new_service_worker_page_test_vm_with_loader_and_browser_context_runtime(
+            "https://message-port-options.test/",
+            &loader,
+        );
+    vm.eval(&format!("{PORT_PROBE}\ncheckPortOptions().then(value=>globalThis.portOptionsResult=value,error=>globalThis.portOptionsResult=String(error));")).unwrap();
+    tokio::time::timeout(std::time::Duration::from_secs(10), async {
+        while vm
+            .eval("globalThis.portOptionsResult !== undefined")
+            .unwrap()
+            != "true"
+        {
+            drain_service_worker_test_turn(&mut vm, &browser_context_runtime, &loader).await;
+        }
+    })
+    .await
+    .expect("message port options probe should settle");
+    let value = vm
+        .eval("JSON.stringify(globalThis.portOptionsResult)")
+        .unwrap();
+    assert_option_rows(&serde_json::from_str(&value).unwrap(), 30);
+}
diff --git a/moli-renderer-v8/src/script_vm/tests/browser_api/mod.rs b/moli-renderer-v8/src/script_vm/tests/browser_api/mod.rs
index 2c00056252..2850a8e67e 100644
--- a/moli-renderer-v8/src/script_vm/tests/browser_api/mod.rs
+++ b/moli-renderer-v8/src/script_vm/tests/browser_api/mod.rs
@@ -16,6 +16,7 @@ mod crypto_subtle_x25519;
 mod date_locale;
 mod details;
 mod event_handlers;
+mod event_listener_options;
 mod events_selection_storage;
 mod gamepad;
 mod ice_candidate;
diff --git a/moli-renderer-v8/src/window_host.rs b/moli-renderer-v8/src/window_host.rs
index 5eee87e6f7..0d37e74043 100644
--- a/moli-renderer-v8/src/window_host.rs
+++ b/moli-renderer-v8/src/window_host.rs
@@ -39,7 +39,7 @@ use super::{
     },
     script_provenance::CompiledStringProvenance,
     util::{
-        callback_arg_string, context_host_from_global_bridge, context_host_ptr_from_global_bridge,
+        context_host_from_global_bridge, context_host_ptr_from_global_bridge,
         context_host_ptr_from_window_object, define_non_enumerable_static_bool_property,
         get_private_value, object_bool_property, object_number_property,
         script_base_url_from_continuation_data, script_base_url_from_host_defined_options,
@@ -47,6 +47,9 @@ use super::{
     },
     webidl,
 };
+use crate::event_listener_args::{
+    AddEventListenerArgs, RemoveEventListenerArgs, parse_listener_args,
+};
 use crate::web_api_interfaces;
 use moli_webapi_declare::{WebApiFunctionTemplate, WebApiObject};
 use std::time::{Duration, SystemTime, UNIX_EPOCH};
@@ -142,124 +145,6 @@ struct IdleDeadlinePrototypeDeclaration {
     time_remaining: (),
 }
 
-#[derive(webidl::WebIdlArgs)]
-#[webidl(prefix = "EventTarget.addEventListener")]
-struct WindowAddEventListenerArgs<'s> {
-    #[webidl(with = window_add_event_listener_call)]
-    call: webidl::ParseOutcome<WindowAddEventListenerCall<'s>>,
-}
-
-#[derive(webidl::WebIdlArgs)]
-#[webidl(prefix = "EventTarget.removeEventListener")]
-struct WindowRemoveEventListenerArgs<'s> {
-    #[webidl(with = window_remove_event_listener_call)]
-    call: webidl::ParseOutcome<WindowRemoveEventListenerCall<'s>>,
-}
-
-struct WindowAddEventListenerCall<'s> {
-    event_type: String,
-    callback: v8::Local<'s, v8::Object>,
-    callback_relevant_context: v8::Local<'s, v8::Context>,
-    incumbent_context: v8::Local<'s, v8::Context>,
-    options: webidl::EventListenerOptions,
-    signal: Option<v8::Local<'s, v8::Object>>,
-}
-
-struct WindowRemoveEventListenerCall<'s> {
-    event_type: String,
-    callback: v8::Local<'s, v8::Object>,
-    options: webidl::EventListenerOptions,
-}
-
-fn window_add_event_listener_call<'s>(
-    scope: &mut v8::PinScope<'s, '_>,
-    args: &v8::FunctionCallbackArguments<'s>,
-    _index: i32,
-) -> Result<webidl::ParseOutcome<WindowAddEventListenerCall<'s>>, webidl::WebIdlError> {
-    let Some(event_type) = callback_arg_string(scope, args, 0) else {
-        return Ok(webidl::ParseOutcome::Skip);
-    };
-    let options = webidl::event_listener_options(scope, args, 2, true);
-    let listener_arg = args.get(1);
-    let current_context = scope.get_current_context();
-    let callback = if let Ok(function) = v8::Local::<v8::Function>::try_from(listener_arg) {
-        let callback = v8::Local::<v8::Object>::from(function);
-        let callback_relevant_context = callback
-            .get_creation_context(scope)
-            .unwrap_or(current_context);
-        Some((callback, callback_relevant_context))
-    } else if listener_arg.is_object() && !listener_arg.is_null_or_undefined() {
-        let Ok(object) = v8::Local::<v8::Object>::try_from(listener_arg) else {
-            return Ok(webidl::ParseOutcome::Skip);
-        };
-        let callback_relevant_context = object
-            .get_creation_context(scope)
-            .unwrap_or(current_context);
-        Some((object, callback_relevant_context))
-    } else {
-        None
-    };
-    let Some((callback, callback_relevant_context)) = callback else {
-        return Ok(webidl::ParseOutcome::Skip);
-    };
-    let incumbent_context = scope.get_incumbent_context().unwrap_or(current_context);
-    Ok(webidl::ParseOutcome::Parsed(WindowAddEventListenerCall {
-        event_type,
-        callback,
-        callback_relevant_context,
-        incumbent_context,
-        signal: signal_from_options_value(scope, args.get(2)),
-        options,
-    }))
-}
-
-fn window_remove_event_listener_call<'s>(
-    scope: &mut v8::PinScope<'s, '_>,
-    args: &v8::FunctionCallbackArguments<'s>,
-    _index: i32,
-) -> Result<webidl::ParseOutcome<WindowRemoveEventListenerCall<'s>>, webidl::WebIdlError> {
-    let Some(event_type) = callback_arg_string(scope, args, 0) else {
-        return Ok(webidl::ParseOutcome::Skip);
-    };
-    let options = webidl::event_listener_options(scope, args, 2, true);
-    let listener_arg = args.get(1);
-    let callback = if let Ok(function) = v8::Local::<v8::Function>::try_from(listener_arg) {
-        Some(v8::Local::<v8::Object>::from(function))
-    } else if listener_arg.is_object() && !listener_arg.is_null_or_undefined() {
-        v8::Local::<v8::Object>::try_from(listener_arg).ok()
-    } else {
-        None
-    };
-    let Some(callback) = callback else {
-        return Ok(webidl::ParseOutcome::Skip);
-    };
-    Ok(webidl::ParseOutcome::Parsed(
-        WindowRemoveEventListenerCall {
-            event_type,
-            callback,
-            options,
-        },
-    ))
-}
-
-fn signal_from_options_value<'s>(
-    scope: &mut v8::PinScope<'s, '_>,
-    value: v8::Local<'s, v8::Value>,
-) -> Option<v8::Local<'s, v8::Object>> {
-    let Ok(options) = v8::Local::<v8::Object>::try_from(value) else {
-        return None;
-    };
-    options
-        .get(scope, v8str(scope, "signal").into())
-        .and_then(|value| {
-            if value.is_null_or_undefined() {
-                None
-            } else {
-                v8::Local::<v8::Object>::try_from(value).ok()
-            }
-        })
-}
-
 pub(super) fn event_target_add_event_listener_callback<'s>(
     scope: &mut v8::PinScope<'s, '_>,
     args: v8::FunctionCallbackArguments<'s>,
@@ -273,16 +158,17 @@ pub(super) fn event_target_add_event_listener_callback<'s>(
         return;
     };
     let host = unsafe { &mut *host_ptr };
-    let parsed = webidl::parse_args::<WindowAddEventListenerArgs>(scope, &args);
-    let Some(parsed) = parsed else {
+    let parsed = parse_listener_args::<AddEventListenerArgs>(scope, &args, "addEventListener");
+    let Some(call) = parsed else {
         return;
     };
-    let webidl::ParseOutcome::Parsed(call) = parsed.call else {
+    let Some(listener) = call.listener else {
         return;
     };
-    let capture = call.options.capture;
-    let once = call.options.once;
-    let signal = call.signal;
+    let options = call.options.options;
+    let capture = options.capture;
+    let once = options.once;
+    let signal = call.options.signal.map(|signal| signal.value());
     if let Some(signal) = signal
         && host.abort_signal_aborted(scope, signal)
     {
@@ -303,17 +189,20 @@ pub(super) fn event_target_add_event_listener_callback<'s>(
         throw_type_error(scope, "Illegal invocation");
         return;
     };
-    let passive = call
-        .options
+    let passive = options
         .passive
         .unwrap_or_else(|| default_passive_value(host, target, &call.event_type));
+    let callback = v8::Local::<v8::Object>::try_from(listener.value(scope))
+        .expect("converted EventListener must remain an object");
+    let callback_relevant_context = listener.relevant_context(scope);
+    let incumbent_context = listener.incumbent_context(scope);
     let Some(callback_id) = host.register_target_event_listener(
         scope,
         target,
         &call.event_type,
-        call.callback,
-        call.callback_relevant_context,
-        call.incumbent_context,
+        callback,
+        callback_relevant_context,
+        incumbent_context,
         capture,
         once,
         passive,
@@ -391,10 +280,12 @@ pub(super) fn event_target_remove_event_listener_callback<'s>(
         return;
     };
     let host = unsafe { &mut *host_ptr };
-    let Some(parsed) = webidl::parse_args::<WindowRemoveEventListenerArgs>(scope, &args) else {
+    let Some(call) =
+        parse_listener_args::<RemoveEventListenerArgs>(scope, &args, "removeEventListener")
+    else {
         return;
     };
-    let webidl::ParseOutcome::Parsed(call) = parsed.call else {
+    let Some(listener) = call.listener else {
         return;
     };
     let capture = call.options.capture;
@@ -411,7 +302,9 @@ pub(super) fn event_target_remove_event_listener_callback<'s>(
         throw_type_error(scope, "Illegal invocation");
         return;
     };
-    host.remove_registered_event_listener(scope, target, &call.event_type, call.callback, capture);
+    let callback = v8::Local::<v8::Object>::try_from(listener.value(scope))
+        .expect("converted EventListener must remain an object");
+    host.remove_registered_event_listener(scope, target, &call.event_type, callback, capture);
 }
 
 pub(super) fn event_target_dispatch_event_callback<'s>(
diff --git a/moli-webidl/src/helpers.rs b/moli-webidl/src/helpers.rs
index c77f4f05f1..834ed28d29 100644
--- a/moli-webidl/src/helpers.rs
+++ b/moli-webidl/src/helpers.rs
@@ -1,4 +1,4 @@
-use crate::types::EventListenerOptionsMembers;
+use crate::types::{AddEventListenerOptionsMembers, EventListenerOptionsMembers};
 use crate::{
     Context, DomString, EventListenerOptions, UnrestrictedDouble, WebIdlError,
     legacy_optional_member, parse_dictionary_object,
@@ -170,69 +170,6 @@ pub fn optional_number_property<'s>(
         .map(Into::into)
 }
 
-/// Parses the third argument shape used by event listener registration.
-///
-/// Boolean values use the legacy capture-only path. Object values are parsed as
-/// `AddEventListenerOptions`. When `observe_passive` is true, the `passive`
-/// member is read even if the resulting value is not otherwise needed, matching
-/// sites that observe getter side effects.
-pub fn event_listener_options<'s>(
-    scope: &mut v8::PinScope<'s, '_>,
-    args: &v8::FunctionCallbackArguments<'s>,
-    index: i32,
-    observe_passive: bool,
-) -> EventListenerOptions {
-    if args.length() <= index {
-        return EventListenerOptions::default();
-    }
-    event_listener_options_value(scope, args.get(index), observe_passive)
-}
-
-pub fn event_listener_options_value<'s>(
-    scope: &mut v8::PinScope<'s, '_>,
-    value: v8::Local<'s, v8::Value>,
-    observe_passive: bool,
-) -> EventListenerOptions {
-    if is_nullish(value) {
-        return EventListenerOptions::default();
-    }
-    if !value.is_object() || value.is_boolean() {
-        return EventListenerOptions {
-            capture: value.boolean_value(scope),
-            once: false,
-            passive: None,
-        };
-    }
-    let Ok(object) = v8::Local::<v8::Object>::try_from(value) else {
-        return EventListenerOptions::default();
-    };
-    if observe_passive {
-        let _ = property(scope, object, "passive");
-    }
-    parse_dictionary_object::<EventListenerOptionsMembers>(scope, object)
-        .map(|parsed| EventListenerOptions {
-            capture: parsed.capture,
-            once: parsed.once,
-            passive: parsed.passive,
-        })
-        .unwrap_or_default()
-}
-
-pub fn event_listener_once_value<'s>(
-    scope: &mut v8::PinScope<'s, '_>,
-    value: v8::Local<'s, v8::Value>,
-) -> bool {
-    event_listener_options_value(scope, value, false).once
-}
-
-pub fn event_listener_once_option<'s>(
-    scope: &mut v8::PinScope<'s, '_>,
-    args: &v8::FunctionCallbackArguments<'s>,
-    index: i32,
-) -> bool {
-    event_listener_options(scope, args, index, false).once
-}
-
 /// Converts `(AddEventListenerOptions or boolean)` through `passive`.
 ///
 /// The caller must convert the platform-specific `signal` member next, before
@@ -247,10 +184,35 @@ pub fn add_event_listener_options_value<'s>(
             ..EventListenerOptions::default()
         });
     };
-    let parsed = parse_dictionary_object::<EventListenerOptionsMembers>(scope, object)?;
+    let parsed = parse_dictionary_object::<AddEventListenerOptionsMembers>(scope, object)?;
     Ok(EventListenerOptions {
         capture: parsed.capture,
         once: parsed.once,
         passive: parsed.passive,
     })
 }
+
+/// Converts removeEventListener's `(EventListenerOptions or boolean)` argument.
+/// Only `capture` belongs to this dictionary; no registration-only getters run.
+pub fn event_listener_options<'s>(
+    scope: &mut v8::PinScope<'s, '_>,
+    args: &v8::FunctionCallbackArguments<'s>,
+    index: i32,
+) -> Result<EventListenerOptions, WebIdlError> {
+    event_listener_options_value(scope, args.get(index))
+}
+
+pub fn event_listener_options_value<'s>(
+    scope: &mut v8::PinScope<'s, '_>,
+    value: v8::Local<'s, v8::Value>,
+) -> Result<EventListenerOptions, WebIdlError> {
+    let capture = if let Ok(object) = v8::Local::<v8::Object>::try_from(value) {
+        parse_dictionary_object::<EventListenerOptionsMembers>(scope, object)?.capture
+    } else {
+        value.boolean_value(scope)
+    };
+    Ok(EventListenerOptions {
+        capture,
+        ..EventListenerOptions::default()
+    })
+}
diff --git a/moli-webidl/src/lib.rs b/moli-webidl/src/lib.rs
index 092bea0471..b3848b5fdd 100644
--- a/moli-webidl/src/lib.rs
+++ b/moli-webidl/src/lib.rs
@@ -49,11 +49,11 @@ pub use convert::{
 };
 pub use error::{Context, WebIdlError, WebIdlErrorKind};
 pub use helpers::{
-    add_event_listener_options_value, dictionary_arg, dictionary_value, event_listener_once_option,
-    event_listener_once_value, event_listener_options, event_listener_options_value, is_nullish,
-    optional_number_property, optional_object_arg, optional_string_property, property,
-    property_non_nullish, property_non_undefined, property_result, symbol_property_result,
-    throw_dom_exception, throw_error, throw_index_size_error, throw_type_error, v8_string,
+    add_event_listener_options_value, dictionary_arg, dictionary_value, event_listener_options,
+    event_listener_options_value, is_nullish, optional_number_property, optional_object_arg,
+    optional_string_property, property, property_non_nullish, property_non_undefined,
+    property_result, symbol_property_result, throw_dom_exception, throw_error,
+    throw_index_size_error, throw_type_error, v8_string,
 };
 pub use moli_webidl_callback::{
     PreparedWebIdlCallbackFunction, PreparedWebIdlCallbackInterface, WebIdlCallbackFunction,
diff --git a/moli-webidl/src/types.rs b/moli-webidl/src/types.rs
index 7edf3e7cbf..c3f318e5b4 100644
--- a/moli-webidl/src/types.rs
+++ b/moli-webidl/src/types.rs
@@ -143,10 +143,17 @@ pub struct EventListenerOptions {
 }
 
 #[derive(WebIdlDictionary)]
-#[webidl(prefix = "AddEventListenerOptions")]
+#[webidl(prefix = "EventListenerOptions")]
 pub(crate) struct EventListenerOptionsMembers {
     #[webidl(default = false)]
     pub(crate) capture: bool,
+}
+
+#[derive(WebIdlDictionary)]
+#[webidl(prefix = "AddEventListenerOptions")]
+pub(crate) struct AddEventListenerOptionsMembers {
+    #[webidl(default = false)]
+    pub(crate) capture: bool,
     #[webidl(default = false)]
     pub(crate) once: bool,
     pub(crate) passive: Option<bool>,