From 7e1d0a998cb7f90e4e2aa65daae5c1d9ffeeaac9 Mon Sep 17 00:00:00 2001
From: Jinwoo-H <jinwoo0825@gmail.com>
Date: Fri, 11 Sep 2026 01:27:53 -0400
Subject: [PATCH] fix(mobile): require a reader for RPC result variants

---
 mobile/src/transport/rpc-operation-compile-fence.ts | 4 ++++
 mobile/src/transport/rpc-operation-result-reader.ts | 5 ++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/mobile/src/transport/rpc-operation-compile-fence.ts b/mobile/src/transport/rpc-operation-compile-fence.ts
index 2e4449da73c..a8af3807257 100644
--- a/mobile/src/transport/rpc-operation-compile-fence.ts
+++ b/mobile/src/transport/rpc-operation-compile-fence.ts
@@ -1,6 +1,7 @@
 import type { RpcClient } from './rpc-client'
 import type { RpcMethodName } from './rpc-params-contract'
 import { defineRpcOperation, runRpcOperation, startRpcOperation } from './rpc-operation'
+import { rpcResultVariants } from './rpc-operation-result-reader'
 import {
   workspaceListAtBarrier,
   workspaceListOrNull,
@@ -24,6 +25,9 @@ import type {
 
 declare const client: RpcClient
 
+// @ts-expect-error a variant reader combinator must have at least one reader
+const _fenceEmptyVariantReaders = rpcResultVariants([])
+
 // FENCE: probe-cannot-take-a-reader
 export const fenceProbeWithReader: CapabilityProbeRpcDefinition<'worktree.ps', 'on-settle'> = {
   name: 'fence.probeWithReader',
diff --git a/mobile/src/transport/rpc-operation-result-reader.ts b/mobile/src/transport/rpc-operation-result-reader.ts
index 0b7e3bef376..b9341e0e8bc 100644
--- a/mobile/src/transport/rpc-operation-result-reader.ts
+++ b/mobile/src/transport/rpc-operation-result-reader.ts
@@ -39,7 +39,10 @@ export function rpcResultVariant<Variant extends string, Schema extends z.ZodTyp
 
 /** Tries each variant in declared order and takes the first that reads. */
 export function rpcResultVariants<Variant extends string, Value>(
-  readers: readonly NamedRpcResultReader<Variant, Value>[]
+  readers: readonly [
+    NamedRpcResultReader<Variant, Value>,
+    ...NamedRpcResultReader<Variant, Value>[]
+  ]
 ): RpcCompatibleReader<unknown, Variant, Value> {
   return (raw) => {
     const issues: RpcDecodeIssue[] = []