feat(Day 49): /v1/doctrines/classify endpoint for topic-dossier UX

New POST endpoint that takes a free-text query and returns top-k
matching doctrines with metadata (name_he, anchor_case, anchor_year,
statute, domain, score, pending_lawyer_review flag).

Powers the frontend topic-dossier panel that appears inline with
lawyer-ask results — user sees related doctrines without navigating
away. Uses the existing classify_doctrines() + load_doctrine_catalog()
internals; no new business logic.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tau_rag/api/fastapi_app.py

@@ -22537,6 +22537,54 @@ def admin_funnel(request: Request, hours: int = 24):  # type: ignore
 # `anchor_case`, `n_leading_cases` — not the full schema (elements,
 # exceptions, keywords stay internal).
 # ──────────────────────────────────────────────────────────────────────
+class _DoctrineClassifyRequest(BaseModel):  # type: ignore
+    text: str
+    k: int = 3
+    min_score: float = 1.0
+
+
+@app.post("/v1/doctrines/classify")
+def doctrines_classify(body: _DoctrineClassifyRequest):  # type: ignore
+    """Day 49 — classify a free-text query against the doctrine catalog.
+
+    Returns the top-k matching doctrines with their metadata so the
+    frontend can render a "related doctrines" panel inline with the
+    lawyer-ask result (topic-dossier UX).
+    """
+    if not (body.text or "").strip():
+        return {"ok": True, "matches": [], "n_total": 0}
+    try:
+        from ..intelligence.doctrine_classifier import (
+            classify_doctrines, load_doctrine_catalog,
+        )
+        cat = load_doctrine_catalog()
+        idx = {d["id"]: d for d in cat.get("doctrines", [])}
+        matches = classify_doctrines(body.text, k=body.k,
+                                      min_score=body.min_score)
+        out = []
+        for m in matches:
+            doc = idx.get(m.doctrine_id, {})
+            leading = (doc.get("leading_cases") or [])[:1]
+            anchor_case = leading[0].get("citation") if leading else None
+            anchor_year = leading[0].get("year") if leading else None
+            out.append({
+                "id":          m.doctrine_id,
+                "name_he":     m.name_he,
+                "domain":      m.domain,
+                "score":       round(m.score, 2),
+                "anchor_case": anchor_case,
+                "anchor_year": anchor_year,
+                "statute":     ((doc.get("statute_refs") or [{}])[0]
+                                .get("law") if doc.get("statute_refs") else None),
+                "pending_review": bool(doc.get("_pending_lawyer_review")),
+            })
+        return {"ok": True, "matches": out, "n_total": len(out)}
+    except Exception as e:
+        return JSONResponse(status_code=500, content={
+            "ok": False, "error": f"{type(e).__name__}: {e}"
+        })
+
+
 @app.get("/v1/doctrines/catalog")
 def doctrines_catalog_public():  # type: ignore
     """Public read-only summary of the curated doctrine catalog."""