fix(opencode): fallback to sh for curl upgrade (#30499)

Co-authored-by: Shoubhit Dash <shoubhit2005@gmail.com>

packages/opencode/src/installation/index.ts

@@ -149,13 +149,20 @@ export const layer: Layer.Layer<Service, never, HttpClient.HttpClient | AppProce
       return `Upgrade failed for ${method}.`
     }
 
+    const upgradeScriptShell = Effect.fnUntraced(function* () {
+      const bashVersion = yield* text(["bash", "--version"])
+      if (bashVersion) return "bash"
+      return "sh"
+    })
+
     const upgradeCurl = Effect.fnUntraced(
       function* (target: string) {
         const response = yield* httpOk.execute(HttpClientRequest.get("https://opencode.ai/install"))
         const body = yield* response.text
         const bodyBytes = new TextEncoder().encode(body)
+        const shell = yield* upgradeScriptShell()
         const result = yield* appProcess.run(
-          ChildProcess.make("bash", [], {
+          ChildProcess.make(shell, [], {
             stdin: Stream.make(bodyBytes),
             env: { VERSION: target },
             extendEnv: true,