Add TMDB poster picker to film detail page

- New movie_images() async function in services/tmdb.py fetches poster
  URLs from TMDB /movie/{id}/images endpoint, filtering for English
  and no-text posters only
- New GET /tmdb/posters endpoint returns list of available posters for
  a TMDB ID
- New POST /films/{film_id}/poster endpoint to save selected poster
  (mirrors the stars endpoint pattern)
- Add "Change Poster" button on detail page (only shown if film has a
  TMDB ID) that opens a 3-column grid of posters
- Selected poster gets accent border, main image updates instantly, no
  page reload needed
- Posters are cached per load to avoid refetching on re-open

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

1 files changed, 96 insertions, 0 deletions

diff --git a/templates/detail.html b/templates/detail.html
index 59779d8..20897b0 100644
--- a/templates/detail.html
+++ b/templates/detail.html
@@ -12,6 +12,23 @@
           <span>{{ film.title[:1] }}</span>
         {% endif %}
       </div>
+
+      {% if film.tmdb_id %}
+      <button
+        type="button"
+        id="change-poster-btn"
+        class="secondary-button"
+        style="width: 100%; margin-top: 12px;"
+        data-tmdb-id="{{ film.tmdb_id }}"
+        data-film-id="{{ film.id }}"
+      >Change Poster</button>
+
+      <div id="poster-picker" style="display: none; margin-top: 12px;">
+        <p id="poster-picker-status" style="color: var(--muted); font-size: 0.86rem; margin: 0 0 10px;">Loading posters…</p>
+        <div id="poster-grid" style="display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px;"></div>
+      </div>
+      {% endif %}
+
       <div class="detail-aside-meta">
         <div>
           <span class="summary-label">Shelf</span>
@@ -122,4 +139,83 @@
       </div>
     </section>
   </article>
+
+{% if film.tmdb_id %}
+<script>
+(function () {
+  const btn = document.getElementById("change-poster-btn");
+  const picker = document.getElementById("poster-picker");
+  const grid = document.getElementById("poster-grid");
+  const status = document.getElementById("poster-picker-status");
+  const filmId = btn.dataset.filmId;
+  const tmdbId = btn.dataset.tmdbId;
+
+  let loaded = false;
+
+  btn.addEventListener("click", async () => {
+    if (picker.style.display === "none") {
+      picker.style.display = "block";
+      btn.textContent = "Close";
+    } else {
+      picker.style.display = "none";
+      btn.textContent = "Change Poster";
+      return;
+    }
+
+    if (loaded) return;
+    status.textContent = "Loading posters…";
+    status.style.display = "block";
+
+    try {
+      const resp = await fetch(`/tmdb/posters?tmdb_id=${tmdbId}`);
+      if (!resp.ok) throw new Error("fetch failed");
+      const data = await resp.json();
+      status.style.display = "none";
+
+      if (!data.posters.length) {
+        status.textContent = "No posters found.";
+        status.style.display = "block";
+        return;
+      }
+
+      grid.innerHTML = data.posters.map((url) => `
+        <button type="button" class="poster-option" data-url="${url}" style="padding: 0; border: 2px solid transparent; border-radius: 6px; overflow: hidden; cursor: pointer; background: none;">
+          <img src="${url}" alt="Poster option" loading="lazy" style="width: 100%; display: block; aspect-ratio: 2/3; object-fit: cover;">
+        </button>
+      `).join("");
+
+      grid.querySelectorAll(".poster-option").forEach((optBtn) => {
+        optBtn.addEventListener("click", async () => {
+          const url = optBtn.dataset.url;
+
+          grid.querySelectorAll(".poster-option").forEach((b) => b.style.borderColor = "transparent");
+          optBtn.style.borderColor = "var(--accent)";
+
+          try {
+            const saveResp = await fetch(`/films/${filmId}/poster`, {
+              method: "POST",
+              headers: { "Content-Type": "application/json" },
+              body: JSON.stringify({ poster_url: url }),
+            });
+            if (!saveResp.ok) return;
+
+            const posterImg = document.querySelector(".poster-large img");
+            if (posterImg) posterImg.src = url;
+            picker.style.display = "none";
+            btn.textContent = "Change Poster";
+          } catch (err) {
+            console.error("Failed to save poster", err);
+          }
+        });
+      });
+
+      loaded = true;
+    } catch (err) {
+      status.textContent = "Failed to load posters.";
+      console.error(err);
+    }
+  });
+})();
+</script>
+{% endif %}
 {% endblock %}