feat(services/bsl): add llm_timing — estimate cook times via LLM for missing corpus data (Paid/BYOK)

app/services/meal_plan/llm_timing.py

@@ -0,0 +1,61 @@
+# app/services/meal_plan/llm_timing.py
+# BSL 1.1 — LLM feature
+"""Estimate cook times for recipes missing corpus prep/cook time fields.
+
+Used only when tier allows `meal_plan_llm_timing`. Falls back gracefully
+when LLMRouter is unavailable.
+"""
+from __future__ import annotations
+
+import logging
+
+logger = logging.getLogger(__name__)
+
+_TIMING_PROMPT = """\
+You are a practical cook. Given a recipe name and its ingredients, estimate:
+1. prep_time: minutes of active prep work (chopping, mixing, etc.)
+2. cook_time: minutes of cooking (oven, stovetop, etc.)
+
+Respond with ONLY two integers on separate lines:
+prep_time
+cook_time
+
+If you cannot estimate, respond with:
+0
+0
+"""
+
+
+def estimate_timing(recipe_name: str, ingredients: list[str], router) -> tuple[int | None, int | None]:
+    """Return (prep_minutes, cook_minutes) for a recipe using LLMRouter.
+
+    Returns (None, None) if the router is unavailable or the response is
+    unparseable. Never raises.
+
+    Args:
+        recipe_name: Name of the recipe.
+        ingredients: List of raw ingredient strings from the corpus.
+        router: An LLMRouter instance (from circuitforge_core.llm).
+    """
+    if router is None:
+        return None, None
+
+    ingredient_list = "\n".join(f"- {i}" for i in (ingredients or [])[:15])
+    prompt = f"Recipe: {recipe_name}\n\nIngredients:\n{ingredient_list}"
+
+    try:
+        response = router.complete(
+            system=_TIMING_PROMPT,
+            user=prompt,
+            max_tokens=16,
+            temperature=0.0,
+        )
+        lines = response.strip().splitlines()
+        prep = int(lines[0].strip()) if lines else 0
+        cook = int(lines[1].strip()) if len(lines) > 1 else 0
+        if prep == 0 and cook == 0:
+            return None, None
+        return prep or None, cook or None
+    except Exception as exc:
+        logger.debug("LLM timing estimation failed for %r: %s", recipe_name, exc)
+        return None, None