Phase 6.5 Day 2: query_id linkage (B1)

recommendations.py:
- Generate query_id (UUID) once per GET /api/recommendations request
- Thread query_id through all 4 tiers: trending, Tier 1 (multi-interest),
Tier 2 (EWMA), Tier 3 (Qdrant recommend)
- Pass query_id kwarg to _multi_interest_recommend()
- Embed query_id + position (0-based index) in every paper dict

search.py:
- Generate query_id once per GET /search request
- Add query_id + position to each paper in results

action_buttons.html:
- Add query_id + position to ALL three hx-vals JSON blobs (save, remove, not-interested)
- Position was previously missing from not-interested buttons

This enables Phase 7 per-feed CTR analysis via:
SELECT query_id, COUNT(DISTINCT paper_id) AS shown,
COUNT(*) FILTER (WHERE event_type='save') AS saved
FROM interactions GROUP BY query_id

Tests: 203 passed, 0 failures

app/routers/recommendations.py

@@ -59,6 +59,9 @@ async def get_recommendations(
     user_id = user_id or str(uuid.uuid4())
     state = await us.ensure_loaded(user_id)
 
+    # Phase 6.5 B1: one query_id per feed request for per-feed CTR analysis
+    query_id = str(uuid.uuid4())
+
     def _empty_resp():
         r = templates.TemplateResponse(
             request,
@@ -79,12 +82,14 @@ async def get_recommendations(
             )
             if trending:
                 papers = []
-                for paper in trending:
+                for idx, paper in enumerate(trending):
                     paper["saved"] = False
                     paper["dismissed"] = False
                     paper["ranker_version"] = _RANKER_VERSION
                     paper["candidate_source"] = "trending_category_fallback"
                     paper["cluster_id"] = ""
+                    paper["query_id"] = query_id
+                    paper["position"] = idx
                     papers.append(paper)
 
                 r = templates.TemplateResponse(
@@ -106,7 +111,7 @@ async def get_recommendations(
 
     # ── Tier 1: Multi-interest clustering + quota fusion (≥5 saves) ──────
     rec_arxiv_ids, paper_tags = await _multi_interest_recommend(
-        user_id, state, seen, REC_LIMIT,
+        user_id, state, seen, REC_LIMIT, query_id=query_id,
     )
 
     # ── Tier 2: EWMA single-vector search (≥3 saves) ──────────────────────
@@ -117,6 +122,7 @@ async def get_recommendations(
                 "ranker_version": _RANKER_VERSION,
                 "candidate_source": "ewma_longterm",
                 "cluster_id": "",
+                "query_id": query_id,
             }
 
     # ── Tier 3: Qdrant Recommend API (≥1 save fallback) ───────────────────
@@ -132,6 +138,7 @@ async def get_recommendations(
                 "ranker_version": _RANKER_VERSION,
                 "candidate_source": "qdrant_recommend",
                 "cluster_id": "",
+                "query_id": query_id,
             }
 
     if not rec_arxiv_ids:
@@ -151,7 +158,7 @@ async def get_recommendations(
     await db.cache_turso_metadata_batch(list(meta.values()))
 
     papers = []
-    for aid in rec_arxiv_ids:
+    for idx, aid in enumerate(rec_arxiv_ids):
         if aid not in meta:
             continue
         tags = paper_tags.get(aid, {})
@@ -163,6 +170,9 @@ async def get_recommendations(
             "ranker_version": tags.get("ranker_version", _RANKER_VERSION),
             "candidate_source": tags.get("candidate_source", ""),
             "cluster_id": tags.get("cluster_id", ""),
+            # Phase 6.5 B1: query_id + position for per-feed CTR
+            "query_id": tags.get("query_id", query_id),
+            "position": idx,
         })
 
     resp = templates.TemplateResponse(
@@ -177,7 +187,8 @@ async def get_recommendations(
 # ── Tier 1: Multi-interest clustering + quota fusion ─────────────────────────
 
 async def _multi_interest_recommend(
-    user_id: str, state, seen: set[str], limit: int
+    user_id: str, state, seen: set[str], limit: int,
+    *, query_id: str = "",
 ) -> tuple[list[str], dict[str, dict]]:
     """
     Full recommendation pipeline (Phase 2b + Phase 4 corrections):
@@ -458,6 +469,7 @@ async def _multi_interest_recommend(
                 "ranker_version": _RANKER_VERSION,
                 "candidate_source": source,
                 "cluster_id": str(cluster_idx) if cluster_idx is not None and cluster_idx >= 0 else "",
+                "query_id": query_id,
             }
 
         return final, paper_tags

app/routers/search.py

@@ -68,13 +68,17 @@ async def search(
                 papers = []
 
     user_id = user_id or str(uuid.uuid4())
+    # Phase 6.5 B1: one query_id per search request for per-feed CTR
+    query_id = str(uuid.uuid4())
     state = await us.ensure_loaded(user_id)
     saved_ids = set(state.positive_list)
     dismissed_ids = set(state.negative_list)
 
-    for p in papers:
+    for idx, p in enumerate(papers):
         p["saved"] = p["arxiv_id"] in saved_ids
         p["dismissed"] = p["arxiv_id"] in dismissed_ids
+        p["query_id"] = query_id
+        p["position"] = idx
 
     if request.headers.get("HX-Request"):
         resp = templates.TemplateResponse(

app/templates/partials/action_buttons.html

@@ -3,6 +3,7 @@
   Expects: paper_id (or paper.arxiv_id), saved (bool), dismissed (bool)
   Optional: source ("search" | "recommendation" | "saved"), position (int)
   Phase 4.5: ranker_version, candidate_source, cluster_id (set by recommendations.py)
+  Phase 6.5: query_id (per-request UUID for feed-level CTR)
   These are returned directly by the /api/papers/{id}/save endpoint
   so they also work as a standalone partial.
 #}
@@ -12,6 +13,8 @@
 {% set _ranker_version = paper.ranker_version | default("") if paper is defined else "" %}
 {% set _candidate_source = paper.candidate_source | default("") if paper is defined else "" %}
 {% set _cluster_id = paper.cluster_id | default("") if paper is defined else "" %}
+{% set _query_id = paper.query_id | default("") if paper is defined else "" %}
+{% set _position = paper.position | default(0) if paper is defined else 0 %}
 
 {% if is_saved %}
   <!-- Already saved — show saved state, allow unsave via not-interested -->
@@ -23,7 +26,7 @@
             hx-post="/api/papers/{{ pid }}/not-interested"
             hx-target="#paper-{{ pid }}"
             hx-swap="outerHTML swap:200ms"
-            hx-vals='{"source": "{{ _source }}", "ranker_version": "{{ _ranker_version }}", "candidate_source": "{{ _candidate_source }}", "cluster_id": "{{ _cluster_id }}"}'>
+            hx-vals='{"source": "{{ _source }}", "position": "{{ _position }}", "ranker_version": "{{ _ranker_version }}", "candidate_source": "{{ _candidate_source }}", "cluster_id": "{{ _cluster_id }}", "query_id": "{{ _query_id }}"}'>
       Remove
     </button>
   </div>
@@ -34,7 +37,7 @@
             hx-post="/api/papers/{{ pid }}/save"
             hx-target="[id='actions-{{ pid }}']"
             hx-swap="innerHTML"
-            hx-vals='{"source": "{{ _source }}", "position": "{{ position | default(0) }}", "ranker_version": "{{ _ranker_version }}", "candidate_source": "{{ _candidate_source }}", "cluster_id": "{{ _cluster_id }}"}'>
+            hx-vals='{"source": "{{ _source }}", "position": "{{ _position }}", "ranker_version": "{{ _ranker_version }}", "candidate_source": "{{ _candidate_source }}", "cluster_id": "{{ _cluster_id }}", "query_id": "{{ _query_id }}"}'>
       ⭐ Save
     </button>
     <!-- Not interested (removes the whole card) -->
@@ -42,9 +45,8 @@
             hx-post="/api/papers/{{ pid }}/not-interested"
             hx-target="#paper-{{ pid }}"
             hx-swap="outerHTML swap:200ms"
-            hx-vals='{"source": "{{ _source }}", "ranker_version": "{{ _ranker_version }}", "candidate_source": "{{ _candidate_source }}", "cluster_id": "{{ _cluster_id }}"}'>
+            hx-vals='{"source": "{{ _source }}", "position": "{{ _position }}", "ranker_version": "{{ _ranker_version }}", "candidate_source": "{{ _candidate_source }}", "cluster_id": "{{ _cluster_id }}", "query_id": "{{ _query_id }}"}'>
       ✕ Not interested
     </button>
   </div>
 {% endif %}
-