Add rewatch patterns stats panel

Adds a "Rewatches" section to /stats that displays films you've watched multiple times, grouped by title. For each rewatched film, shows:
- Watch count (e.g., "3×")
- Rating history (e.g., ✦ → ✦✦ → ✦) with accent highlight when ratings drift
- Days between first and last watch

Changes:
- routers/stats.py: Group films by title in _build_stats_payload, compute rewatch details (ratings, days between, rating change flag), add rewatch_patterns key
- templates/stats.html: Add "Rewatches" panel HTML and JS renderer (renderLists)

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

2 files changed, 55 insertions, 1 deletions

diff --git a/routers/stats.py b/routers/stats.py
index 67b5141..2abc493 100644
--- a/routers/stats.py
+++ b/routers/stats.py
@@ -1,4 +1,4 @@
-from collections import Counter
+from collections import Counter, defaultdict
 from calendar import month_name
 from datetime import date, timedelta
 
@@ -67,6 +67,29 @@ def _build_stats_payload(films: list[Film]) -> dict:
     total_watched = len(films)
     rewatched = sum(1 for film in films if film.rewatch or film.rewatch_count > 0)
 
+    title_groups = defaultdict(list)
+    for film in films:
+        title_groups[film.title].append(film)
+
+    rewatch_details = []
+    for title, entries in title_groups.items():
+        if len(entries) < 2:
+            continue
+        sorted_entries = sorted(entries, key=lambda f: f.date_watched or date.min)
+        ratings = [e.stars for e in sorted_entries]
+        first_date = sorted_entries[0].date_watched
+        last_date = sorted_entries[-1].date_watched
+        days_between = (last_date - first_date).days if first_date and last_date else None
+        rewatch_details.append({
+            "title": title,
+            "watches": len(sorted_entries),
+            "ratings": ratings,
+            "days_between": days_between,
+            "rating_changed": len({r for r in ratings if r > 0}) > 1,
+        })
+
+    rewatch_details.sort(key=lambda x: (-x["watches"], x["title"]))
+
     today = date.today()
     start_day = today - timedelta(days=364)
     trailing_days = []
@@ -119,6 +142,7 @@ def _build_stats_payload(films: list[Film]) -> dict:
             "total_watched": total_watched,
             "rate": round(rewatched / total_watched, 4) if total_watched else 0,
         },
+        "rewatch_patterns": rewatch_details,
         "watched_with_breakdown": [
             {"watched_with": watched_with_value, "count": count}
             for watched_with_value, count in sorted(watched_with.items(), key=lambda item: (-item[1], item[0]))
diff --git a/templates/stats.html b/templates/stats.html
index 9b71679..6f271bd 100644
--- a/templates/stats.html
+++ b/templates/stats.html
@@ -98,6 +98,16 @@
       </div>
       <ol id="film-decades" class="stats-list"></ol>
     </section>
+
+    <section class="stats-panel stats-panel-wide">
+      <div class="stats-panel-header">
+        <div>
+          <p class="eyebrow">Films</p>
+          <h2>Rewatches</h2>
+        </div>
+      </div>
+      <div id="rewatch-patterns-list" class="stats-list"></div>
+    </section>
   </section>
 {% endblock %}
 
@@ -164,6 +174,26 @@
         <strong>${rate}%</strong>
         <span>${data.rewatch_rate.rewatched} of ${data.rewatch_rate.total_watched} watched films were rewatches.</span>
       `;
+
+      const rewatchPatterns = document.getElementById("rewatch-patterns-list");
+      if (data.rewatch_patterns && data.rewatch_patterns.length > 0) {
+        rewatchPatterns.innerHTML = data.rewatch_patterns.map((item) => {
+          const stars = (n) => (n > 0 ? "✦".repeat(n) : "—");
+          const ratingHistory = item.ratings.map(stars).join(" → ");
+          const drift = item.rating_changed
+            ? `<span style="color:var(--accent)">${ratingHistory}</span>`
+            : `<span style="color:var(--muted)">${ratingHistory}</span>`;
+          const gap = item.days_between != null
+            ? `<span style="color:var(--subtle);font-size:13px">${item.days_between}d apart</span>`
+            : "";
+          return `<div class="stats-list-row">
+            <span>${item.title}</span>
+            <span style="display:flex;gap:12px;align-items:center">${gap}${drift}<strong>${item.watches}×</strong></span>
+          </div>`;
+        }).join("");
+      } else {
+        rewatchPatterns.innerHTML = "<p style=\"color:var(--muted);font-size:14px;margin:0\">No rewatches yet.</p>";
+      }
     }
 
     function renderHeatmap(days) {