fix(core): route Muse models to Meta prompt (#42036)

Co-authored-by: Aiden Cline <rekram1-node@users.noreply.github.com>

packages/core/src/plugin/system-prompt.ts

@@ -23,7 +23,11 @@ export const GooglePlugin = make("google", (id) => (id.includes("gemini-") ? PRO
 export const AnthropicPlugin = make("anthropic", (id) => (id.includes("claude") ? PROMPT_ANTHROPIC : undefined))
 export const KimiPlugin = make("kimi", (id) => (id.includes("kimi") ? PROMPT_KIMI : undefined))
 export const ArceePlugin = make("arcee", (id) => (id.includes("trinity") ? PROMPT_TRINITY : undefined))
-export const MetaPlugin = make("meta", (id) => (id.includes("muse-spark") ? PROMPT_META : undefined))
+export const MetaPlugin = make("meta", (id) => {
+  if (!id.includes("muse")) return
+  const name = id.includes("muse-glimmer") ? "Muse Glimmer" : "Muse Spark"
+  return PROMPT_META.replaceAll("{{MODEL_NAME}}", name)
+})
 
 export const Plugins = [OpenAIPlugin, GooglePlugin, AnthropicPlugin, KimiPlugin, ArceePlugin, MetaPlugin] as const
 

packages/core/src/plugin/system-prompt/meta.txt

@@ -1,4 +1,4 @@
-You are OpenCode, a coding agent that helps users with software engineering tasks. You are powered by Muse Spark, a large language model trained by Meta MSL.
+You are OpenCode, a coding agent that helps users with software engineering tasks. You are powered by {{MODEL_NAME}}, a large language model trained by Meta MSL.
 
 Use the instructions below and the tools available to assist the user.
 
@@ -55,5 +55,5 @@ Use the instructions below and the tools available to assist the user.
 - NEVER use comments as a place for long-winded chain-of-thought. Long thinking texts must be generated as private reasoning. Comments in code must be appropriately concise.
 
 # User Help & Feedback
-- Users can give feedback or report issues at https://github.com/anomalyco/opencode and mention that they are using Meta Muse Spark.
+- Users can give feedback or report issues at https://github.com/anomalyco/opencode and mention that they are using Meta {{MODEL_NAME}}.
 - When users ask directly about OpenCode (eg. "can OpenCode do...", "are you able to do...") or its features (eg. implement a hook, write a slash command, or install an MCP server), use the `webfetch` tool to gather information to answer the question from the V2 OpenCode docs at https://opencode.ai/v2/docs/.

packages/core/test/plugin/system-prompt.test.ts

@@ -90,6 +90,36 @@ describe("SystemPromptPlugin", () => {
     }),
   )
 
+  it.effect("selects the Meta prompt for Muse family model IDs", () =>
+    Effect.gen(function* () {
+      const hooks = yield* PluginHooks.Service
+      const pluginHost = yield* makeHost
+      yield* SystemPromptPlugin.MetaPlugin.effect(pluginHost)
+
+      yield* Effect.forEach(
+        [
+          ["meta/muse-spark-preview", "Muse Spark"],
+          ["muse-spark-1.2", "Muse Spark"],
+          ["meta/muse-glimmer-30b", "Muse Glimmer"],
+          ["muse-glimmer-30b", "Muse Glimmer"],
+        ] as const,
+        ([id, name]) => {
+          const event = context(id)
+          return hooks.trigger("session", "context", event).pipe(
+            Effect.tap(() =>
+              Effect.sync(() => {
+                expect(event.system[0]?.text).toContain(`powered by ${name},`)
+                expect(event.system[0]?.text).toContain(`using Meta ${name}.`)
+                expect(event.system[0]?.text).not.toContain("{{MODEL_NAME}}")
+              }),
+            ),
+          )
+        },
+        { discard: true },
+      )
+    }),
+  )
+
   it.effect("preserves an explicit agent system prompt", () =>
     Effect.gen(function* () {
       const agents = yield* Agent.Service