diff --git a/packages/app/src/components/settings-general.tsx b/packages/app/src/components/settings-general.tsx
index 8060ae94d9..535bd72064 100644
--- a/packages/app/src/components/settings-general.tsx
+++ b/packages/app/src/components/settings-general.tsx
@@ -329,6 +329,7 @@ export const SettingsGeneral: Component = () => {
             label={(o) => o.label}
             onSelect={(option) => {
               if (!option) return
+              if (option.value === currentShell()) return
               globalSync.updateConfig({ shell: option.value })
             }}
             variant="secondary"
diff --git a/packages/opencode/src/config/config.ts b/packages/opencode/src/config/config.ts
index 817f8c3e38..c79e950e90 100644
--- a/packages/opencode/src/config/config.ts
+++ b/packages/opencode/src/config/config.ts
@@ -759,18 +759,23 @@ export const layer = Layer.effect(
       const patch = writableGlobal(config)
 
       let next: Info
+      let changed: boolean
       if (!file.endsWith(".jsonc")) {
         const existing = ConfigParse.effectSchema(Info, ConfigParse.jsonc(before, file), file)
         const merged = mergeDeep(writable(existing), patch)
-        yield* fs.writeFileString(file, JSON.stringify(merged, null, 2)).pipe(Effect.orDie)
+        const serialized = JSON.stringify(merged, null, 2)
+        changed = serialized !== before
+        if (changed) yield* fs.writeFileString(file, serialized).pipe(Effect.orDie)
         next = merged
       } else {
         const updated = patchJsonc(before, patch)
         next = ConfigParse.effectSchema(Info, ConfigParse.jsonc(updated, file), file)
-        yield* fs.writeFileString(file, updated).pipe(Effect.orDie)
+        changed = updated !== before
+        if (changed) yield* fs.writeFileString(file, updated).pipe(Effect.orDie)
       }
 
-      yield* invalidate()
+      // Only tear down running instances if the config actually changed.
+      if (changed) yield* invalidate()
       return next
     })