From 22d9688bb1e00acf8818b2e55ce1bab9a7c2b239 Mon Sep 17 00:00:00 2001
From: danbusse <81775558+danbusse@users.noreply.github.com>
Date: Mon, 22 Jun 2026 22:29:08 -0600
Subject: [PATCH] fix: strengthen JSON structure requirements in system prompt

---
 backend/app/services/ai/prompts.py | 25 +++++++++++--------------
 1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/backend/app/services/ai/prompts.py b/backend/app/services/ai/prompts.py
index 5716a65..a4ec59a 100644
--- a/backend/app/services/ai/prompts.py
+++ b/backend/app/services/ai/prompts.py
@@ -27,16 +27,13 @@ SYSTEM_PROMPT = (
     "preamble, no commentary outside the JSON. Your card names must exactly match "
     "official Magic card names (English). Every card must be legal in Commander "
     "and within the commander's colour identity.\n\n"
-    "CRITICAL: Your response must use EXACTLY this JSON structure:\n"
-    "{\n"
-    '  "deck_name": "string",\n'
-    '  "strategy_summary": "string",\n'
-    '  "cards": [\n'
-    '    {"name": "Card Name", "slot": "creature|instant|sorcery|enchantment|artifact|planeswalker|land|battle", "quantity": 1, "reasoning": "..."}\n'
-    "  ],\n"
-    '  "cuts": []\n'
-    "}\n"
-    "Do NOT use any other key names. The cards array must contain exactly the non-commander cards."
+    "CRITICAL JSON REQUIREMENTS:\n"
+    "1. Use EXACTLY these top-level keys: \"deck_name\", \"strategy_summary\", \"cards\", \"cuts\"\n"
+    "2. Do NOT use \"commander\", \"decklist\", \"deck\", or any other key names\n"
+    "3. The \"cards\" array must contain ALL 99 non-commander cards\n"
+    "4. Do NOT include a separate commander entry — it is tracked separately\n"
+    "5. Card names with apostrophes must be properly escaped in JSON strings\n"
+    "6. Every card object must have: \"name\", \"slot\", \"quantity\", \"reasoning\""
 )
 
 
@@ -59,7 +56,7 @@ def generate_prompt(
         f"CONSTRAINTS:\n{constraint_text}\n"
         f"{owned_list_text}\n"
         f"DECK REQUIREMENTS:\n"
-        f"- Exactly 99 cards (not counting the commander)\n"
+        f"- Exactly 99 cards in the \"cards\" array (not counting the commander)\n"
         f"- All cards must be legal in Commander and within {commander}'s colour identity\n"
         f"- Include a balanced mana base (35-40 lands for most strategies)\n"
         f"- Include ramp (8-12 pieces), card draw (8-10 pieces), removal (8-10 pieces), "
@@ -67,7 +64,7 @@ def generate_prompt(
         f"- Slot values: creature, instant, sorcery, enchantment, artifact, planeswalker, land, battle\n"
         f"- Quantity for basic lands may be >1; all other cards quantity = 1\n"
         f"- The 'reasoning' field must explain why the card fits THIS specific deck\n\n"
-        f"Respond with the JSON object only."
+        f"Respond with the JSON object only. Use exactly these keys: deck_name, strategy_summary, cards, cuts."
     )
     return SYSTEM_PROMPT, user_message
 
@@ -109,7 +106,7 @@ def complete_prompt(
         f"- Analyse existing cards to infer strategy and fill gaps (ramp, draw, removal, win-cons)\n"
         f"- The 'cards' array contains ONLY the new cards you are recommending\n"
         f"- strategy_summary should describe how the completed deck plays\n\n"
-        f"Respond with the JSON object only."
+        f"Respond with the JSON object only. Use exactly these keys: deck_name, strategy_summary, cards, cuts."
     )
     return SYSTEM_PROMPT, user_message
 
@@ -155,6 +152,6 @@ def cull_prompt(
         f"- The 'cards' array contains all {target_count} REMAINING cards after cuts\n"
         f"- Provide specific reasoning for each cut explaining why it's weaker than what stays\n"
         f"- strategy_summary describes the refined deck after cuts\n\n"
-        f"Respond with the JSON object only."
+        f"Respond with the JSON object only. Use exactly these keys: deck_name, strategy_summary, cards, cuts."
     )
     return SYSTEM_PROMPT, user_message