refactor(prompts): hoist Kilo model-specific prompt checks to the front (#9815)

* refactor(cli): hoist Kilo model-specific prompt checks to the front

Extract the Kilo metadata-driven prompt selection into a dedicated
kiloPrompt() helper and invoke it with an early return at the top of
provider(). This ensures Kilo-specific prompt routing takes priority
over upstream heuristics and leaves the upstream if-chain untouched,
reducing future merge conflicts when opencode adjusts its own
model-specific prompt branching.

No behavior change.

* fix(cli): preserve Ling prompt fallback precedence

* fix(cli): keep prompt annotations scoped

---------

Co-authored-by: kiloconnect[bot] <240665456+kiloconnect[bot]@users.noreply.github.com>
Co-authored-by: marius-kilocode <marius@kilocode.ai>

packages/opencode/src/session/system.ts

@@ -37,24 +37,30 @@ export function soul() {
 
 export function provider(model: Provider.Model) {
   // kilocode_change start
-  switch (model.prompt) {
-    case "anthropic":
-      return [PROMPT_ANTHROPIC]
-    case "anthropic_without_todo":
-      return [PROMPT_DEFAULT]
-    case "beast":
-      return [PROMPT_BEAST]
-    case "codex":
-      return [PROMPT_CODEX]
-    case "gemini":
-      return [PROMPT_GEMINI]
-    case "gpt55":
-      return [PROMPT_GPT55]
-    case "ling":
-      return [PROMPT_LING]
-    case "trinity":
-      return [PROMPT_TRINITY]
+  function prompt() {
+    switch (model.prompt) {
+      case "anthropic":
+        return [PROMPT_ANTHROPIC]
+      case "anthropic_without_todo":
+        return [PROMPT_DEFAULT]
+      case "beast":
+        return [PROMPT_BEAST]
+      case "codex":
+        return [PROMPT_CODEX]
+      case "gemini":
+        return [PROMPT_GEMINI]
+      case "gpt55":
+        return [PROMPT_GPT55]
+      case "ling":
+        return [PROMPT_LING]
+      case "trinity":
+        return [PROMPT_TRINITY]
+    }
+    return undefined
   }
+
+  const kilo = prompt()
+  if (kilo) return kilo
   // kilocode_change end
 
   if (model.api.id.includes("gpt-4") || model.api.id.includes("o1") || model.api.id.includes("o3"))

packages/opencode/test/kilocode/system-prompt.test.ts

@@ -9,6 +9,7 @@ import PROMPT_CODEX from "../../src/session/prompt/codex.txt"
 import PROMPT_GEMINI from "../../src/session/prompt/gemini.txt"
 import PROMPT_GPT from "../../src/session/prompt/gpt.txt"
 import PROMPT_GPT55 from "../../src/session/prompt/kilocode-gpt-5.5.txt"
+import PROMPT_LING from "../../src/session/prompt/ling.txt"
 import PROMPT_TRINITY from "../../src/session/prompt/trinity.txt"
 
 describe("SystemPrompt.provider", () => {
@@ -78,6 +79,24 @@ describe("SystemPrompt.provider", () => {
       expect(result).toEqual([PROMPT_ANTHROPIC])
     })
 
+    test("Ling fallback runs after upstream model id heuristics", () => {
+      const model = ProviderTest.model({
+        prompt: undefined,
+        api: { id: "gpt-5-ling", url: "https://example.com", npm: "@ai-sdk/openai" },
+      })
+      const result = SystemPrompt.provider(model)
+      expect(result).toEqual([PROMPT_GPT])
+    })
+
+    test("Ling fallback is selected after upstream heuristics miss", () => {
+      const model = ProviderTest.model({
+        prompt: undefined,
+        api: { id: "ling-2", url: "https://example.com", npm: "@ai-sdk/openai" },
+      })
+      const result = SystemPrompt.provider(model)
+      expect(result).toEqual([PROMPT_LING])
+    })
+
     test("GPT-5.5 model ids are not prompt-special without metadata", () => {
       const model = ProviderTest.model({
         prompt: undefined,