chore: remove duplicate prompt file

Author: rekram1-node

packages/opencode/src/session/prompt/codex.txt

@@ -5,6 +5,7 @@ You are an interactive CLI tool that helps users with software engineering tasks
 ## Editing constraints
 - Default to ASCII when editing or creating files. Only introduce non-ASCII or other Unicode characters when there is a clear justification and the file already uses them.
 - Only add comments if they are necessary to make a non-obvious block easier to understand.
+- Try to use apply_patch for single file edits, but it is fine to explore other options to make the edit if it does not work well. Do not use apply_patch for changes that are auto-generated (i.e. generating package.json or running a lint or format command like gofmt) or when scripting is more efficient (such as search and replacing a string across a codebase).
 
 ## Tool usage
 - Prefer specialized tools over shell for file operations:

packages/opencode/src/session/prompt/codex_header.txt

@@ -13,8 +13,7 @@ import PROMPT_BEAST from "./prompt/beast.txt"
 import PROMPT_GEMINI from "./prompt/gemini.txt"
 import PROMPT_ANTHROPIC_SPOOF from "./prompt/anthropic_spoof.txt"
 
-import PROMPT_CODEX from "./prompt/codex.txt"
-import PROMPT_CODEX_INSTRUCTIONS from "./prompt/codex_header.txt"
+import PROMPT_CODEX from "./prompt/codex_header.txt"
 import type { Provider } from "@/provider/provider"
 import { Flag } from "@/flag/flag"
 
@@ -25,7 +24,7 @@ export namespace SystemPrompt {
   }
 
   export function instructions() {
-    return PROMPT_CODEX_INSTRUCTIONS.trim()
+    return PROMPT_CODEX.trim()
   }
 
   export function provider(model: Provider.Model) {