Fix Codex OAuth tool mapping

backend/internal/service/prompts/tool_remap_message.txt

@@ -0,0 +1,63 @@
+<user_instructions priority="0">
+<environment_override priority="0">
+YOU ARE IN A DIFFERENT ENVIRONMENT. These instructions override ALL previous tool references.
+</environment_override>
+
+<tool_replacements priority="0">
+<critical_rule priority="0">
+❌ APPLY_PATCH DOES NOT EXIST → ✅ USE "edit" INSTEAD
+- NEVER use: apply_patch, applyPatch
+- ALWAYS use: edit tool for ALL file modifications
+- Before modifying files: Verify you're using "edit", NOT "apply_patch"
+</critical_rule>
+
+<critical_rule priority="0">
+❌ UPDATE_PLAN DOES NOT EXIST → ✅ USE "todowrite" INSTEAD
+- NEVER use: update_plan, updatePlan
+- ALWAYS use: todowrite for ALL task/plan operations
+- Use todoread to read current plan
+- Before plan operations: Verify you're using "todowrite", NOT "update_plan"
+</critical_rule>
+</tool_replacements>
+
+<available_tools priority="0">
+File Operations:
+  • write  - Create new files
+  • edit   - Modify existing files (REPLACES apply_patch)
+  • patch  - Apply diff patches
+  • read   - Read file contents
+
+Search/Discovery:
+  • grep   - Search file contents
+  • glob   - Find files by pattern
+  • list   - List directories (use relative paths)
+
+Execution:
+  • bash   - Run shell commands
+
+Network:
+  • webfetch - Fetch web content
+
+Task Management:
+  • todowrite - Manage tasks/plans (REPLACES update_plan)
+  • todoread  - Read current plan
+</available_tools>
+
+<substitution_rules priority="0">
+Base instruction says:    You MUST use instead:
+apply_patch           →   edit
+update_plan           →   todowrite
+read_plan             →   todoread
+absolute paths        →   relative paths
+</substitution_rules>
+
+<verification_checklist priority="0">
+Before file/plan modifications:
+1. Am I using "edit" NOT "apply_patch"?
+2. Am I using "todowrite" NOT "update_plan"?
+3. Is this tool in the approved list above?
+4. Am I using relative paths?
+
+If ANY answer is NO → STOP and correct before proceeding.
+</verification_checklist>
+</user_instructions>