feat: add meta muse system prompt (#36122)

packages/opencode/test/session/system.test.ts

@@ -1,10 +1,11 @@
-import { describe, expect } from "bun:test"
+import { describe, expect, test } from "bun:test"
 import { LayerNode } from "@opencode-ai/core/effect/layer-node"
 import { Effect, Layer } from "effect"
 import type { Agent } from "../../src/agent/agent"
 import { NamedError } from "@opencode-ai/core/util/error"
 import { Skill } from "../../src/skill"
 import { Permission } from "../../src/permission"
+import type { Provider } from "../../src/provider/provider"
 import { SystemPrompt } from "../../src/session/system"
 import { MCP } from "../../src/mcp"
 import { testEffect } from "../lib/effect"
@@ -83,6 +84,12 @@ const it = testEffect(
 )
 
 describe("session.system", () => {
+  test("selects the Meta prompt for Muse Spark model IDs", () => {
+    expect(SystemPrompt.provider({ api: { id: "meta/muse-spark-preview" } } as Provider.Model)[0]).toContain(
+      "Meta Muse Spark",
+    )
+  })
+
   it.effect("skills output is sorted by name and stable across calls", () =>
     Effect.gen(function* () {
       const prompt = yield* SystemPrompt.Service