diff --git a/mobile/src/transport/rpc-operation-compile-fence.ts b/mobile/src/transport/rpc-operation-compile-fence.ts
index ac14b326fd2..c57c4950a01 100644
--- a/mobile/src/transport/rpc-operation-compile-fence.ts
+++ b/mobile/src/transport/rpc-operation-compile-fence.ts
@@ -9,6 +9,7 @@ import {
 } from './rpc-operation'
 import { rpcResultVariants } from './rpc-operation-result-reader'
 import {
+  pushTestWithoutParams,
   workspaceListAtBarrier,
   workspaceListOrNull,
   workspaceRowsReader,
@@ -146,6 +147,17 @@ export async function fenceBarrierAndParams(): Promise<void> {
   )
 }
 
+// A method the catalog declares params-less keeps every shape a shipped sender may use. An
+// explicit `null` is the one that matters: `params: null` is not the frame that omits the key,
+// so narrowing this to omission would rewrite bytes main already puts on the wire.
+export async function fenceParamlessSend(): Promise<void> {
+  await runRpcOperation(client, pushTestWithoutParams, null)
+  await runRpcOperation(client, pushTestWithoutParams, undefined)
+  await runRpcOperation(client, pushTestWithoutParams)
+  // @ts-expect-error a method that declares no params accepts none
+  await runRpcOperation(client, pushTestWithoutParams, { path: 'main.js' })
+}
+
 export async function fenceVerdictTypes(): Promise<void> {
   // @ts-expect-error the probe's policy yields a boolean, not the other family's rows
   const rows: WorkspaceRows = await runRpcOperation(client, worktreePsProbe, {})
diff --git a/mobile/src/transport/rpc-operation-test-families.ts b/mobile/src/transport/rpc-operation-test-families.ts
index 73554b7a4f8..a93c0ba1abf 100644
--- a/mobile/src/transport/rpc-operation-test-families.ts
+++ b/mobile/src/transport/rpc-operation-test-families.ts
@@ -54,6 +54,14 @@ export const worktreePsProbe = defineRpcOperation({
   barrier: 'on-settle'
 })
 
+/** A method the catalog declares with no params at all, so `RpcSendParams` reads `void`. */
+export const pushTestWithoutParams = defineRpcOperation({
+  name: 'test.pushTestWithoutParams',
+  method: 'notifications.testPush',
+  acceptance: 'method-not-found-refusal',
+  barrier: 'on-settle'
+})
+
 export const terminalStreamOpener = defineRpcOperation({
   name: 'test.terminalStreamOpener',
   method: 'terminal.subscribe',
diff --git a/mobile/src/transport/rpc-operation.ts b/mobile/src/transport/rpc-operation.ts
index a836dc429fb..620f1516a12 100644
--- a/mobile/src/transport/rpc-operation.ts
+++ b/mobile/src/transport/rpc-operation.ts
@@ -173,10 +173,12 @@ export async function runRpcOperation<
 >(
   client: UnvalidatedRpcRequestPort,
   operation: RpcOperation<Method, Acceptance, Variant, Value, 'on-settle'>,
-  params: RpcSendParams<Method>,
-  options?: SendRequestOptions
+  // Shares the deferred sender's tuple so the two cannot disagree about what a params-less
+  // method may be called with: the catalog types those `void`, and an explicit `null` is the
+  // frame several shipped senders already put on the wire.
+  ...args: RpcSendArguments<Method>
 ): Promise<RpcVerdict<Acceptance, Value>> {
-  const outcome = await request(client, operation, params, options)
+  const outcome = await request(client, operation, args[0], args[1])
   // oxlint-disable-next-line typescript/consistent-type-assertions -- SAFETY: Preserve the established response shape at this boundary.
   return interpretRpcOutcome(operation, outcome) as RpcVerdict<Acceptance, Value>
 }