Restructure into full project layout

backend/app/services/ai/prompts.py

@@ -0,0 +1,150 @@
+"""
+Prompt templates for the three deck modes.
+
+Output contract — Claude returns a single JSON object:
+{
+  "deck_name": "string",
+  "strategy_summary": "string",
+  "cards": [
+    {
+      "name": "Card Name",          // append [UNOWNED] when prefer_owned=True
+      "slot": "creature|instant|sorcery|enchantment|artifact|planeswalker|land|battle",
+      "quantity": 1,
+      "reasoning": "1-2 sentences"
+    }
+  ],
+  "cuts": [                         // CULL mode only
+    { "name": "Card Name", "reasoning": "..." }
+  ]
+}
+"""
+
+SYSTEM_PROMPT = (
+    "You are an expert Magic: The Gathering deck builder specialising in the Commander "
+    "(EDH) format. You have deep knowledge of card synergies, mana curves, colour "
+    "identity rules, staples, budget alternatives, and current metagame trends.\n\n"
+    "You always respond with a single valid JSON object — no markdown fences, no "
+    "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."
+)
+
+
+def generate_prompt(
+    commander: str,
+    playstyle: str | None,
+    constraint_text: str,
+    owned_list_text: str,
+) -> tuple[str, str]:
+    playstyle_line = (
+        f"Playstyle preference: {playstyle}"
+        if playstyle
+        else "Playstyle preference: not specified — choose the strongest strategy for this commander."
+    )
+
+    user_message = (
+        f"Build a complete Commander deck for the following commander.\n\n"
+        f"COMMANDER: {commander}\n"
+        f"{playstyle_line}\n\n"
+        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"- 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), "
+        f"and win conditions appropriate to the playstyle\n"
+        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."
+    )
+    return SYSTEM_PROMPT, user_message
+
+
+def complete_prompt(
+    commander: str,
+    playstyle: str | None,
+    existing_cards: list[dict],
+    constraint_text: str,
+    owned_list_text: str,
+) -> tuple[str, str]:
+    existing_count = sum(c.get("quantity", 1) for c in existing_cards)
+    slots_needed = 99 - existing_count
+
+    playstyle_line = (
+        f"Playstyle preference: {playstyle}"
+        if playstyle
+        else "Playstyle preference: infer from existing cards."
+    )
+
+    existing_formatted = "\n".join(
+        f"- {c['card_name']} ({c.get('slot', 'unknown')})"
+        + (f" x{c['quantity']}" if c.get('quantity', 1) > 1 else "")
+        for c in existing_cards
+    )
+
+    user_message = (
+        f"The user has a partial Commander deck and needs suggestions to complete it.\n\n"
+        f"COMMANDER: {commander}\n"
+        f"{playstyle_line}\n"
+        f"SLOTS NEEDED: {slots_needed} more cards to reach 99\n\n"
+        f"EXISTING CARDS ({existing_count} cards):\n{existing_formatted}\n\n"
+        f"CONSTRAINTS:\n{constraint_text}\n"
+        f"{owned_list_text}\n"
+        f"INSTRUCTIONS:\n"
+        f"- Suggest exactly {slots_needed} new cards to fill remaining slots\n"
+        f"- Do not repeat any card already in the existing list\n"
+        f"- All cards must be legal in Commander and within {commander}'s colour identity\n"
+        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."
+    )
+    return SYSTEM_PROMPT, user_message
+
+
+def cull_prompt(
+    commander: str,
+    existing_cards: list[dict],
+    target_count: int,
+    constraint_text: str,
+    owned_list_text: str,
+    prefer_owned: bool,
+) -> tuple[str, str]:
+    current_count = sum(c.get("quantity", 1) for c in existing_cards)
+    cuts_needed = current_count - target_count
+
+    existing_formatted = "\n".join(
+        f"- {c['card_name']} ({c.get('slot', 'unknown')})"
+        + (" [OWNED]" if c.get("is_owned") else "")
+        for c in existing_cards
+    )
+
+    ownership_note = (
+        "\n- IMPORTANT: Prioritise cutting cards NOT marked [OWNED] first — "
+        "this saves the user money on cards they would have to buy."
+        if prefer_owned
+        else ""
+    )
+
+    user_message = (
+        f"The user's Commander deck is oversized and needs to be culled.\n\n"
+        f"COMMANDER: {commander}\n"
+        f"CURRENT SIZE: {current_count} cards\n"
+        f"TARGET SIZE: {target_count} cards\n"
+        f"CUTS NEEDED: {cuts_needed} cards\n\n"
+        f"CURRENT DECKLIST:\n{existing_formatted}\n\n"
+        f"CONSTRAINTS:\n{constraint_text}\n"
+        f"{owned_list_text}\n"
+        f"INSTRUCTIONS:\n"
+        f"- Recommend exactly {cuts_needed} cards to cut\n"
+        f"- Identify redundancy, weak synergy, overcosted cards, and cards that "
+        f"don't advance the primary strategy\n"
+        f"- Order the 'cuts' array from most-recommended to least-recommended cut{ownership_note}\n"
+        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."
+    )
+    return SYSTEM_PROMPT, user_message