diff --git a/registry/components/caption-editorial-emphasis/caption-editorial-emphasis.html b/registry/components/caption-editorial-emphasis/caption-editorial-emphasis.html
index 50b41a1220..2622b09a80 100644
--- a/registry/components/caption-editorial-emphasis/caption-editorial-emphasis.html
+++ b/registry/components/caption-editorial-emphasis/caption-editorial-emphasis.html
@@ -80,7 +80,7 @@
 
       .word {
         display: inline-block;
-        color: #f5f0d0;
+        color: var(--hf-caption-primary, #f5f0d0);
         text-shadow:
           0 2px 12px rgba(0, 0, 0, 0.6),
           0 4px 24px rgba(0, 0, 0, 0.35);
@@ -95,20 +95,13 @@
         font-style: normal;
       }
 
-      .word--italic {
-        font-family: "Inter", sans-serif;
-        font-size: 86px;
-        font-weight: 400;
-        font-style: italic;
-      }
-
       .word--emphasis {
         font-family: "Playfair Display", serif;
         font-size: 180px;
         font-weight: 800;
         font-style: italic;
         line-height: 0.9;
-        color: #f5f0d0;
+        color: var(--hf-caption-primary, #f5f0d0);
       }
     </style>
   </head>
@@ -129,268 +122,507 @@
     </div>
 
     <script>
-      var DURATION = 8;
-      var SAFE_WIDTH = 1800;
-      var ENTRY_DUR = 0.1;
-      var SLIDE_DUR = 0.2;
-
-      var _fitCanvas = document.createElement("canvas");
-      var _fitCtx = _fitCanvas.getContext("2d");
-      function fitFontSize(text, baseFontSize, fontWeight, fontFamily, maxWidth) {
-        var size = baseFontSize;
-        var minSize = Math.floor(baseFontSize * 0.45);
-        while (size > minSize) {
-          _fitCtx.font = fontWeight + " " + size + "px " + fontFamily;
-          if (_fitCtx.measureText(text).width <= maxWidth) return size;
-          size -= 2;
+      // IIFE: keep every template's runtime private to itself so two caption
+      // components pasted into one composition document can't clobber each
+      // other's hfAttach/hfBuild via shared script-scope names (boot is async,
+      // so collisions surface AFTER all scripts have executed).
+      (function () {
+        var HF_COMPOSITION_ID = "caption-editorial-emphasis";
+        var HF_ROOT_ID = "editorial-emphasis";
+        var HF_GROUP_SELECTOR = ".caption-block";
+
+        var HF_DEMO_DATA = {
+          version: 1,
+          segments: [
+            {
+              start: 0,
+              text: "Every great video starts with a single frame. HyperFrames lets you write HTML and render professional video. No timeline. No drag and drop. Just code that becomes cinema.",
+              words: [
+                { text: "Every", start: 0.0, end: 0.3 },
+                { text: "great", start: 0.3, end: 0.55 },
+                { text: "video", start: 0.55, end: 0.85 },
+                { text: "starts", start: 0.85, end: 1.1 },
+                { text: "with", start: 1.1, end: 1.25 },
+                { text: "a", start: 1.25, end: 1.35 },
+                { text: "single", start: 1.35, end: 1.65 },
+                { text: "frame.", start: 1.65, end: 2.0 },
+                { text: "HyperFrames", start: 2.1, end: 2.65 },
+                { text: "lets", start: 2.65, end: 2.85 },
+                { text: "you", start: 2.85, end: 2.95 },
+                { text: "write", start: 2.95, end: 3.15 },
+                { text: "HTML", start: 3.15, end: 3.55 },
+                { text: "and", start: 3.55, end: 3.65 },
+                { text: "render", start: 3.65, end: 3.95 },
+                { text: "professional", start: 3.95, end: 4.45 },
+                { text: "video.", start: 4.45, end: 4.8 },
+                { text: "No", start: 4.9, end: 5.05 },
+                { text: "timeline.", start: 5.05, end: 5.45 },
+                { text: "No", start: 5.5, end: 5.65 },
+                { text: "drag", start: 5.65, end: 5.85 },
+                { text: "and", start: 5.85, end: 5.95 },
+                { text: "drop.", start: 5.95, end: 6.25 },
+                { text: "Just", start: 6.35, end: 6.55 },
+                { text: "code", start: 6.55, end: 6.8 },
+                { text: "that", start: 6.8, end: 6.95 },
+                { text: "becomes", start: 6.95, end: 7.3 },
+                { text: "cinema.", start: 7.3, end: 7.7 },
+              ],
+            },
+          ],
+        };
+
+        /* ── HyperFrames caption-data runtime (shared across caption templates) ── */
+        var HF_CONTRACT_VERSION = 1;
+        var HF_DEFAULT_RESOLUTION = { width: 1920, height: 1080 };
+
+        function hfFlattenSegments(segments) {
+          var out = [];
+          (segments || []).forEach(function (seg) {
+            ((seg && seg.words) || []).forEach(function (w) {
+              var start = Math.max(0, Number(w.start) || 0);
+              out.push({
+                text: String(w.word || w.text || "").trim(),
+                start: start,
+                end: Math.max(start, Number(w.end) || 0),
+              });
+            });
+          });
+          out.sort(function (a, b) {
+            return a.start - b.start;
+          });
+          return out.filter(function (w) {
+            return w.text.length > 0;
+          });
         }
-        return minSize;
-      }
 
-      // Generic transcript words
-      var W = [
-        { text: "Every", start: 0.0, end: 0.3 },
-        { text: "great", start: 0.3, end: 0.55 },
-        { text: "video", start: 0.55, end: 0.85 },
-        { text: "starts", start: 0.85, end: 1.1 },
-        { text: "with", start: 1.1, end: 1.25 },
-        { text: "a", start: 1.25, end: 1.35 },
-        { text: "single", start: 1.35, end: 1.65 },
-        { text: "frame.", start: 1.65, end: 2.0 },
-        { text: "HyperFrames", start: 2.1, end: 2.65 },
-        { text: "lets", start: 2.65, end: 2.85 },
-        { text: "you", start: 2.85, end: 2.95 },
-        { text: "write", start: 2.95, end: 3.15 },
-        { text: "HTML", start: 3.15, end: 3.55 },
-        { text: "and", start: 3.55, end: 3.65 },
-        { text: "render", start: 3.65, end: 3.95 },
-        { text: "professional", start: 3.95, end: 4.45 },
-        { text: "video.", start: 4.45, end: 4.8 },
-        { text: "No", start: 4.9, end: 5.05 },
-        { text: "timeline.", start: 5.05, end: 5.45 },
-        { text: "No", start: 5.5, end: 5.65 },
-        { text: "drag", start: 5.65, end: 5.85 },
-        { text: "and", start: 5.85, end: 5.95 },
-        { text: "drop.", start: 5.95, end: 6.25 },
-        { text: "Just", start: 6.35, end: 6.55 },
-        { text: "code", start: 6.55, end: 6.8 },
-        { text: "that", start: 6.8, end: 6.95 },
-        { text: "becomes", start: 6.95, end: 7.3 },
-        { text: "cinema.", start: 7.3, end: 7.7 },
-      ];
-
-      // Block layout: [wordIndex, type] — n=normal, i=italic, e=emphasis(large)
-      // Emphasis words: HyperFrames(8), HTML(12), professional(15), code(24), cinema.(27)
-      var BLOCKS = [
-        {
-          line1: [
-            [0, "n"],
-            [1, "n"],
-            [2, "n"],
-          ],
-          line2: [
-            [3, "n"],
-            [4, "n"],
-          ],
-        },
-        {
-          line1: [
-            [5, "n"],
-            [6, "n"],
-          ],
-          line2: [[7, "e"]],
-        },
-        { line1: [[8, "e"]], line2: null },
-        {
-          line1: [
-            [9, "n"],
-            [10, "n"],
-            [11, "n"],
-          ],
-          line2: [[12, "e"]],
-        },
-        {
-          line1: [
-            [13, "n"],
-            [14, "n"],
-          ],
-          line2: [[15, "e"]],
-        },
-        {
-          line1: [
-            [16, "n"],
-            [17, "n"],
-          ],
-          line2: null,
-        },
-        {
-          line1: [[18, "n"]],
-          line2: [
-            [19, "n"],
-            [20, "n"],
-          ],
-        },
-        {
-          line1: [
-            [21, "n"],
-            [22, "n"],
-          ],
-          line2: null,
-        },
-        {
-          line1: [
-            [23, "i"],
-            [24, "e"],
-          ],
-          line2: null,
-        },
-        {
-          line1: [
-            [25, "n"],
-            [26, "n"],
-          ],
-          line2: [[27, "e"]],
-        },
-      ];
-
-      var CLASS_MAP = { n: "word word--normal", i: "word word--italic", e: "word word--emphasis" };
-
-      function computeLineSize(linePairs) {
-        var hasEmphasis = linePairs.some(function (p) {
-          return p[1] === "e";
-        });
-        if (hasEmphasis) {
-          var lineText = linePairs
-            .map(function (p) {
-              return W[p[0]].text;
-            })
-            .join(" ");
-          return fitFontSize(lineText, 180, "800", "Playfair Display", SAFE_WIDTH);
+        function hfDeriveDuration(words) {
+          var end = 0;
+          words.forEach(function (w) {
+            if (w.end > end) end = w.end;
+          });
+          return end;
         }
-        var lineText = linePairs
-          .map(function (p) {
-            return W[p[0]].text;
-          })
-          .join(" ");
-        return fitFontSize(lineText, 86, "400", "Inter", SAFE_WIDTH);
-      }
 
-      function buildBlocks() {
-        var stage = document.getElementById("caption-stage");
-        BLOCKS.forEach(function (block, bi) {
-          var el = document.createElement("div");
-          el.className = "caption-block";
-          el.id = "b" + bi;
-
-          var l1Size = computeLineSize(block.line1);
-          var l1 = document.createElement("div");
-          l1.className = "caption-line";
-          l1.id = "b" + bi + "L1";
-          block.line1.forEach(function (pair, wi) {
-            var span = document.createElement("span");
-            span.className = CLASS_MAP[pair[1]];
-            span.id = "b" + bi + "L1w" + wi;
-            span.textContent = W[pair[0]].text;
-            if (pair[1] === "e") {
-              span.style.fontSize = l1Size + "px";
-            } else {
-              span.style.fontSize = l1Size + "px";
+        function hfValidate(data) {
+          if (!data || typeof data !== "object") return { ok: false, reason: "not-an-object" };
+          if (data.version != null) {
+            // Number("v2") is NaN and NaN > x is always false — an explicit
+            // finite check keeps malformed versions from slipping past the gate.
+            var hfVersion = Number(data.version);
+            if (!Number.isFinite(hfVersion) || Math.floor(hfVersion) > HF_CONTRACT_VERSION) {
+              return { ok: false, reason: "unsupported-version" };
             }
-            l1.appendChild(span);
+          }
+          if (!Array.isArray(data.segments) || data.segments.length === 0) {
+            return { ok: false, reason: "no-segments" };
+          }
+          if (data.displayMode != null && data.displayMode !== "full") {
+            return { ok: false, reason: "unsupported-displayMode" };
+          }
+          var words = hfFlattenSegments(data.segments);
+          if (words.length === 0) return { ok: false, reason: "no-words" };
+          return { ok: true, words: words, durationS: hfDeriveDuration(words) };
+        }
+
+        function hfApplyStageConfig(data, durationS) {
+          var res = (data && data.resolution) || HF_DEFAULT_RESOLUTION;
+          // Mirror the published validator's <=8192 bound defensively — the
+          // validator is an optional pre-flight, and an unbounded stage size
+          // would OOM render workers.
+          var W = Math.min(
+            8192,
+            Math.max(1, Math.round(Number(res.width) || HF_DEFAULT_RESOLUTION.width)),
+          );
+          var H = Math.min(
+            8192,
+            Math.max(1, Math.round(Number(res.height) || HF_DEFAULT_RESOLUTION.height)),
+          );
+          var root = document.getElementById(HF_ROOT_ID);
+          [document.documentElement, document.body, root].forEach(function (el) {
+            el.style.width = W + "px";
+            el.style.height = H + "px";
           });
-          el.appendChild(l1);
-
-          if (block.line2) {
-            var l2Size = computeLineSize(block.line2);
-            var l2 = document.createElement("div");
-            l2.className = "caption-line";
-            l2.id = "b" + bi + "L2";
-            block.line2.forEach(function (pair, wi) {
-              var span = document.createElement("span");
-              span.className = CLASS_MAP[pair[1]];
-              span.id = "b" + bi + "L2w" + wi;
-              span.textContent = W[pair[0]].text;
-              if (pair[1] === "e") {
-                span.style.fontSize = l2Size + "px";
-              } else {
-                span.style.fontSize = l2Size + "px";
-              }
-              l2.appendChild(span);
+          root.setAttribute("data-width", String(W));
+          root.setAttribute("data-height", String(H));
+          root.setAttribute("data-duration", String(durationS));
+          var brand = (data && data.brand) || {};
+          if (typeof brand.primaryColor === "string" && brand.primaryColor) {
+            root.style.setProperty("--hf-caption-primary", brand.primaryColor);
+          } else {
+            root.style.removeProperty("--hf-caption-primary");
+          }
+          if (typeof brand.accentColor === "string" && brand.accentColor) {
+            root.style.setProperty("--hf-caption-accent", brand.accentColor);
+          } else {
+            root.style.removeProperty("--hf-caption-accent");
+          }
+          return {
+            W: W,
+            H: H,
+            scaleX: W / 1920,
+            scaleY: H / 1080,
+            fontScale: Math.min(W, H) / 1080,
+          };
+        }
+
+        function hfPublishStatus(status) {
+          window.__HF_CAPTION_STATUS = status;
+          document
+            .getElementById(HF_ROOT_ID)
+            .setAttribute("data-caption-status", status.ok ? "ok" : "failed");
+        }
+
+        function hfRunGate(words, durationS, failReason) {
+          if (failReason) {
+            hfPublishStatus({
+              ok: false,
+              present: false,
+              contained: false,
+              reason: failReason,
+              version: HF_CONTRACT_VERSION,
+              durationS: durationS || 0,
             });
-            el.appendChild(l2);
+            return;
           }
+          var root = document.getElementById(HF_ROOT_ID);
+          var rootRect = root.getBoundingClientRect();
+          var groups = root.querySelectorAll(HF_GROUP_SELECTOR);
+          var present = false;
+          var contained = true;
+          var tokens = [];
+          words.forEach(function (w) {
+            var t = w.text.toLowerCase().replace(/[^a-z0-9]/g, "");
+            if (t) tokens.push(t);
+          });
+          groups.forEach(function (el) {
+            var prevOpacity = el.style.opacity;
+            var prevVisibility = el.style.visibility;
+            el.style.opacity = "1";
+            el.style.visibility = "visible";
+            var r = el.getBoundingClientRect();
+            if (r.width > 0 && r.height > 0) {
+              var text = (el.textContent || "").toLowerCase();
+              for (var i = 0; i < tokens.length; i++) {
+                if (text.indexOf(tokens[i]) !== -1) {
+                  present = true;
+                  break;
+                }
+              }
+              if (
+                r.left < rootRect.left - 1 ||
+                r.right > rootRect.right + 1 ||
+                r.top < rootRect.top - 1 ||
+                r.bottom > rootRect.bottom + 1
+              ) {
+                contained = false;
+              }
+            }
+            el.style.opacity = prevOpacity;
+            el.style.visibility = prevVisibility;
+          });
+          hfPublishStatus({
+            ok: present && contained,
+            present: present,
+            contained: contained,
+            version: HF_CONTRACT_VERSION,
+            durationS: durationS,
+          });
+        }
 
-          stage.appendChild(el);
-        });
-      }
+        var HF_STOPWORDS = new Set([
+          "the",
+          "a",
+          "an",
+          "and",
+          "or",
+          "but",
+          "is",
+          "are",
+          "was",
+          "were",
+          "to",
+          "of",
+          "in",
+          "on",
+          "at",
+          "for",
+          "with",
+          "by",
+          "from",
+          "as",
+          "it",
+          "its",
+          "this",
+          "that",
+          "these",
+          "those",
+          "be",
+          "been",
+          "have",
+          "has",
+          "had",
+          "do",
+          "does",
+          "did",
+          "will",
+          "would",
+          "could",
+          "should",
+          "may",
+          "might",
+          "must",
+          "can",
+          "if",
+          "then",
+          "so",
+          "just",
+          "not",
+          "no",
+          "yes",
+          "up",
+          "out",
+          "about",
+          "into",
+          "over",
+          "after",
+          "before",
+          "your",
+          "you",
+          "our",
+          "we",
+          "they",
+          "them",
+          "their",
+          "there",
+          "here",
+          "when",
+          "what",
+          "which",
+          "who",
+          "how",
+          "all",
+          "any",
+          "some",
+          "more",
+          "most",
+          "other",
+          "than",
+          "too",
+          "very",
+          "also",
+          "because",
+        ]);
+
+        function hfIsEmphasisWord(text) {
+          var clean = String(text)
+            .toLowerCase()
+            .replace(/[^a-z]/g, "");
+          return clean.length >= 5 && !HF_STOPWORDS.has(clean);
+        }
 
-      buildBlocks();
-
-      // Scale blocks that exceed safe width
-      (function fitBlocks() {
-        BLOCKS.forEach(function (block, bi) {
-          var el = document.getElementById("b" + bi);
-          el.style.opacity = "1";
-          el.style.position = "relative";
-          var lines = el.querySelectorAll(".caption-line");
-          var maxW = 0;
-          lines.forEach(function (line) {
-            if (line.scrollWidth > maxW) maxW = line.scrollWidth;
+        var DURATION, SAFE_WIDTH;
+        var ENTRY_DUR = 0.1;
+        var SLIDE_DUR = 0.2;
+
+        var _fitCanvas = document.createElement("canvas");
+        var _fitCtx = _fitCanvas.getContext("2d");
+        function fitFontSize(text, baseFontSize, fontWeight, fontFamily, maxWidth) {
+          var size = baseFontSize;
+          var minSize = Math.floor(baseFontSize * 0.45);
+          // minSize is a hard floor returned unverified below — self-heal
+          // accepts residual overflow at the floor (clipped by the stage)
+          // rather than shrinking below legibility.
+          while (size > minSize) {
+            _fitCtx.font = fontWeight + " " + size + "px " + fontFamily;
+            if (_fitCtx.measureText(text).width <= maxWidth) return size;
+            size -= 2;
+          }
+          return minSize;
+        }
+
+        var CLASS_MAP = { n: "word word--normal", e: "word word--emphasis" };
+
+        var W = [];
+        var BLOCKS = [];
+
+        var MAX_WORDS_PER_BLOCK = 5;
+        var PAUSE_THRESHOLD = 0.1;
+
+        function hfMakeBlocks(words) {
+          var blocks = [];
+          var current = [];
+          words.forEach(function (w, i) {
+            current.push(i);
+            var isEmph = hfIsEmphasisWord(w.text);
+            var punctuation = /[,.:!?]$/.test(w.text);
+            var next = words[i + 1];
+            var pause = next ? next.start - w.end : Infinity;
+            if (
+              isEmph ||
+              punctuation ||
+              pause >= PAUSE_THRESHOLD ||
+              current.length >= MAX_WORDS_PER_BLOCK ||
+              !next
+            ) {
+              if (isEmph && current.length > 1) {
+                blocks.push({
+                  line1: current.slice(0, -1).map(function (ix) {
+                    return [ix, "n"];
+                  }),
+                  line2: [[current[current.length - 1], "e"]],
+                });
+              } else if (isEmph) {
+                blocks.push({ line1: [[current[0], "e"]], line2: null });
+              } else if (current.length > 3) {
+                var split = Math.ceil(current.length / 2);
+                blocks.push({
+                  line1: current.slice(0, split).map(function (ix) {
+                    return [ix, "n"];
+                  }),
+                  line2: current.slice(split).map(function (ix) {
+                    return [ix, "n"];
+                  }),
+                });
+              } else {
+                blocks.push({
+                  line1: current.map(function (ix) {
+                    return [ix, "n"];
+                  }),
+                  line2: null,
+                });
+              }
+              current = [];
+            }
           });
-          if (maxW > SAFE_WIDTH) {
-            var s = SAFE_WIDTH / maxW;
-            el.style.transform = "scale(" + s + ")";
+          return blocks;
+        }
+
+        function hfTeardown() {
+          document.getElementById("caption-stage").innerHTML = "";
+        }
+
+        function hfBuild(words, layout, durationS) {
+          DURATION = durationS;
+          var stage = document.getElementById("caption-stage");
+          var fontNormal = Math.round(86 * layout.fontScale);
+          var fontEmphasis = Math.round(180 * layout.fontScale);
+          var marginX = Math.round(60 * layout.scaleX);
+          var blockH = Math.round(430 * layout.fontScale);
+          SAFE_WIDTH = layout.W - marginX * 2;
+          stage.style.left = marginX + "px";
+          stage.style.width = SAFE_WIDTH + "px";
+          stage.style.height = blockH + "px";
+          stage.style.top = Math.max(0, layout.H - blockH - Math.round(70 * layout.scaleY)) + "px";
+
+          W = words;
+          BLOCKS = hfMakeBlocks(words);
+
+          function computeLineSize(linePairs) {
+            var hasEmphasis = linePairs.some(function (p) {
+              return p[1] === "e";
+            });
+            var lineText = linePairs
+              .map(function (p) {
+                return W[p[0]].text;
+              })
+              .join(" ");
+            if (hasEmphasis) {
+              return fitFontSize(lineText, fontEmphasis, "800", "Playfair Display", SAFE_WIDTH);
+            }
+            return fitFontSize(lineText, fontNormal, "400", "Inter", SAFE_WIDTH);
           }
-          el.style.opacity = "0";
-          el.style.position = "";
-        });
-      })();
 
-      window.__timelines = window.__timelines || {};
-      var tl = gsap.timeline({ paused: true });
+          function buildBlocks() {
+            BLOCKS.forEach(function (block, bi) {
+              var el = document.createElement("div");
+              el.className = "caption-block";
+              el.id = "b" + bi;
+
+              var l1Size = computeLineSize(block.line1);
+              var l1 = document.createElement("div");
+              l1.className = "caption-line";
+              l1.id = "b" + bi + "L1";
+              block.line1.forEach(function (pair, wi) {
+                var span = document.createElement("span");
+                span.className = CLASS_MAP[pair[1]];
+                span.id = "b" + bi + "L1w" + wi;
+                span.textContent = W[pair[0]].text;
+                span.style.fontSize = l1Size + "px";
+                l1.appendChild(span);
+              });
+              el.appendChild(l1);
+
+              if (block.line2) {
+                var l2Size = computeLineSize(block.line2);
+                var l2 = document.createElement("div");
+                l2.className = "caption-line";
+                l2.id = "b" + bi + "L2";
+                block.line2.forEach(function (pair, wi) {
+                  var span = document.createElement("span");
+                  span.className = CLASS_MAP[pair[1]];
+                  span.id = "b" + bi + "L2w" + wi;
+                  span.textContent = W[pair[0]].text;
+                  span.style.fontSize = l2Size + "px";
+                  l2.appendChild(span);
+                });
+                el.appendChild(l2);
+              }
 
-      var allEls = BLOCKS.map(function (_, i) {
-        return document.getElementById("b" + i);
-      });
+              stage.appendChild(el);
+            });
+          }
 
-      function blockStart(bi) {
-        return W[BLOCKS[bi].line1[0][0]].start;
-      }
+          buildBlocks();
+
+          // Scale blocks that exceed safe width
+          function fitBlocks() {
+            BLOCKS.forEach(function (block, bi) {
+              var el = document.getElementById("b" + bi);
+              el.style.opacity = "1";
+              el.style.position = "relative";
+              var lines = el.querySelectorAll(".caption-line");
+              var maxW = 0;
+              lines.forEach(function (line) {
+                if (line.scrollWidth > maxW) maxW = line.scrollWidth;
+              });
+              if (maxW > SAFE_WIDTH) {
+                var s = SAFE_WIDTH / maxW;
+                el.style.transform = "scale(" + s + ")";
+              }
+              el.style.opacity = "0";
+              el.style.position = "";
+            });
+          }
 
-      BLOCKS.forEach(function (block, bi) {
-        var el = allEls[bi];
-        var start = blockStart(bi);
-        var nextStart = bi < BLOCKS.length - 1 ? blockStart(bi + 1) : DURATION;
-
-        allEls.forEach(function (other, oi) {
-          if (oi !== bi) tl.set(other, { opacity: 0 }, start);
-        });
-        tl.set(el, { opacity: 1 }, start);
-
-        block.line1.forEach(function (pair, wi) {
-          var wordEl = document.getElementById("b" + bi + "L1w" + wi);
-          var wordStart = W[pair[0]].start;
-          tl.set(wordEl, { opacity: 0, scale: 1.12, transformOrigin: "0% 100%" }, start);
-          tl.to(
-            wordEl,
-            { opacity: 1, scale: 1, duration: ENTRY_DUR, ease: "power2.out" },
-            wordStart,
-          );
-        });
+          fitBlocks();
+
+          var tl = gsap.timeline({ paused: true });
 
-        if (block.line2) {
-          var hasEmphasis = block.line2.some(function (p) {
-            return p[1] === "e";
+          var allEls = BLOCKS.map(function (_, i) {
+            return document.getElementById("b" + i);
           });
-          var l2El = document.getElementById("b" + bi + "L2");
-          if (hasEmphasis) {
-            var l2Start = W[block.line2[0][0]].start;
-            tl.set(l2El, { opacity: 0, x: -1920 }, start);
-            tl.to(l2El, { opacity: 1, x: 0, duration: SLIDE_DUR, ease: "power2.out" }, l2Start);
-          } else {
-            tl.set(l2El, { opacity: 1 }, start);
-            block.line2.forEach(function (pair, wi) {
-              var wordEl = document.getElementById("b" + bi + "L2w" + wi);
+
+          function blockStart(bi) {
+            return W[BLOCKS[bi].line1[0][0]].start;
+          }
+
+          BLOCKS.forEach(function (block, bi) {
+            var el = allEls[bi];
+            var start = blockStart(bi);
+            var nextStart = bi < BLOCKS.length - 1 ? blockStart(bi + 1) : DURATION;
+
+            // Each block already owns its full opacity lifecycle (set 1 at its
+            // own start, then set back to 0 at its own nextStart below), and
+            // blocks occupy non-overlapping windows, so explicitly hiding every
+            // OTHER block here was redundant and made timeline construction
+            // O(blocks^2) — this collapsed under dense stress transcripts (many
+            // single-word emphasis blocks). Removed; behavior is unchanged
+            // (verified against templates.test.ts).
+
+            tl.set(el, { opacity: 1 }, start);
+
+            block.line1.forEach(function (pair, wi) {
+              var wordEl = document.getElementById("b" + bi + "L1w" + wi);
               var wordStart = W[pair[0]].start;
               tl.set(wordEl, { opacity: 0, scale: 1.12, transformOrigin: "0% 100%" }, start);
               tl.to(
@@ -399,14 +631,94 @@
                 wordStart,
               );
             });
-          }
+
+            if (block.line2) {
+              var hasEmphasis = block.line2.some(function (p) {
+                return p[1] === "e";
+              });
+              var l2El = document.getElementById("b" + bi + "L2");
+              if (hasEmphasis) {
+                var l2Start = W[block.line2[0][0]].start;
+                tl.set(l2El, { opacity: 0, x: -layout.W }, start);
+                tl.to(l2El, { opacity: 1, x: 0, duration: SLIDE_DUR, ease: "power2.out" }, l2Start);
+              } else {
+                tl.set(l2El, { opacity: 1 }, start);
+                block.line2.forEach(function (pair, wi) {
+                  var wordEl = document.getElementById("b" + bi + "L2w" + wi);
+                  var wordStart = W[pair[0]].start;
+                  tl.set(wordEl, { opacity: 0, scale: 1.12, transformOrigin: "0% 100%" }, start);
+                  tl.to(
+                    wordEl,
+                    { opacity: 1, scale: 1, duration: ENTRY_DUR, ease: "power2.out" },
+                    wordStart,
+                  );
+                });
+              }
+            }
+
+            tl.set(el, { opacity: 0 }, nextStart);
+          });
+
+          tl.to({}, { duration: DURATION }, 0);
+          return tl;
         }
 
-        tl.set(el, { opacity: 0 }, nextStart);
-      });
+        var hfCurrentTimeline = null;
 
-      tl.to({}, { duration: DURATION }, 0);
-      window.__timelines["caption-editorial-emphasis"] = tl;
+        function hfAttach(data) {
+          var v = hfValidate(data);
+          if (!v.ok) {
+            hfRunGate([], 0, v.reason);
+            return;
+          }
+          if (hfCurrentTimeline) {
+            hfCurrentTimeline.kill();
+            hfCurrentTimeline = null;
+          }
+          hfTeardown();
+          var layout = hfApplyStageConfig(data, v.durationS);
+          var tl = hfBuild(v.words, layout, v.durationS);
+          tl.set({}, {}, v.durationS); // pin timeline length to the data-derived duration
+          // GSAP quirk (confirmed 3.14.2): a fresh timeline already reports position 0,
+          // so seek(0) is treated as a no-op and skips rendering .set() calls scheduled
+          // at t=0 — the first frame would show pre-timeline CSS defaults (usually
+          // hidden). render(time, suppressEvents, force) with force=true bypasses that.
+          tl.render(0, true, true);
+          hfCurrentTimeline = tl;
+          window.__timelines = window.__timelines || {};
+          window.__timelines[HF_COMPOSITION_ID] = tl;
+          hfRunGate(v.words, v.durationS, null);
+        }
+        window.__HF_CAPTION_ATTACH__ = hfAttach;
+
+        (function hfBoot() {
+          function start(data) {
+            var ready =
+              document.fonts && document.fonts.ready ? document.fonts.ready : Promise.resolve();
+            ready.then(function () {
+              // A manual window.__HF_CAPTION_ATTACH__ call that lands while the
+              // sibling fetch / fonts.ready are still pending must win — never
+              // clobber it with the late-arriving boot payload.
+              if (hfCurrentTimeline) return;
+              hfAttach(data);
+            });
+          }
+          if (window.__HF_CAPTION__) {
+            start(window.__HF_CAPTION__);
+            return;
+          }
+          fetch("./caption-data.json")
+            .then(function (r) {
+              return r.ok ? r.json() : null;
+            })
+            .catch(function () {
+              return null;
+            })
+            .then(function (json) {
+              start(json || HF_DEMO_DATA);
+            });
+        })();
+      })();
     </script>
   </body>
 </html>
diff --git a/registry/components/caption-emoji-pop/caption-emoji-pop.html b/registry/components/caption-emoji-pop/caption-emoji-pop.html
index f8a863d2e8..11d7c77f86 100644
--- a/registry/components/caption-emoji-pop/caption-emoji-pop.html
+++ b/registry/components/caption-emoji-pop/caption-emoji-pop.html
@@ -125,343 +125,705 @@
     </div>
 
     <script>
-      var DURATION = 8;
-      var SAFE_ZONE_WIDTH = 1400;
-      var CAPTION_FONT_SIZE = 72;
-      var MAX_WORDS_PER_GROUP = 3;
-      var WORD_SPACING = 14;
-      var PAUSE_THRESHOLD = 0.1;
-      var ENTRY_FRAMES = 4;
-      var EXIT_FRAMES = 3;
-      var FPS = 30;
-      var ENTRY_DURATION = ENTRY_FRAMES / FPS;
-      var EXIT_DURATION = EXIT_FRAMES / FPS;
-      var FONT_WIDTH_SAFETY = 1.14;
-      var PRIMARY_COLOR = "#FFFFFF";
-      var ACCENT_COLORS = ["#FF76FF", "#FF0002", "#B2F7FF"];
-      var KEYWORDS = new Set(["hyperframes", "html", "professional", "code", "cinema"]);
-      var TRANSITION_WORDS = new Set([
-        "the",
-        "a",
-        "an",
-        "and",
-        "or",
-        "but",
-        "is",
-        "are",
-        "was",
-        "were",
-        "to",
-        "of",
-        "in",
-        "on",
-        "at",
-        "for",
-        "with",
-        "by",
-        "from",
-        "as",
-        "it",
-        "its",
-        "this",
-        "that",
-        "these",
-        "those",
-        "be",
-        "been",
-        "have",
-        "has",
-        "had",
-        "do",
-        "does",
-        "did",
-        "will",
-        "would",
-        "could",
-        "should",
-        "may",
-        "might",
-        "must",
-        "can",
-        "if",
-        "then",
-        "so",
-        "just",
-        "not",
-        "no",
-        "yes",
-        "up",
-        "out",
-        "about",
-      ]);
-
-      // Emoji map for key words
-      var WORD_EMOJI = {
-        hyperframes: "🎬",
-        html: "💻",
-        professional: "✨",
-        code: "⌨️",
-        cinema: "🎥",
-        video: "📹",
-        frame: "🖼️",
-      };
-
-      var TRANSCRIPT = [
-        { text: "Every", start: 0.0, end: 0.3 },
-        { text: "great", start: 0.3, end: 0.55 },
-        { text: "video", start: 0.55, end: 0.85 },
-        { text: "starts", start: 0.85, end: 1.1 },
-        { text: "with", start: 1.1, end: 1.25 },
-        { text: "a", start: 1.25, end: 1.35 },
-        { text: "single", start: 1.35, end: 1.65 },
-        { text: "frame.", start: 1.65, end: 2.0 },
-        { text: "HyperFrames", start: 2.1, end: 2.65 },
-        { text: "lets", start: 2.65, end: 2.85 },
-        { text: "you", start: 2.85, end: 2.95 },
-        { text: "write", start: 2.95, end: 3.15 },
-        { text: "HTML", start: 3.15, end: 3.55 },
-        { text: "and", start: 3.55, end: 3.65 },
-        { text: "render", start: 3.65, end: 3.95 },
-        { text: "professional", start: 3.95, end: 4.45 },
-        { text: "video.", start: 4.45, end: 4.8 },
-        { text: "No", start: 4.9, end: 5.05 },
-        { text: "timeline.", start: 5.05, end: 5.45 },
-        { text: "No", start: 5.5, end: 5.65 },
-        { text: "drag", start: 5.65, end: 5.85 },
-        { text: "and", start: 5.85, end: 5.95 },
-        { text: "drop.", start: 5.95, end: 6.25 },
-        { text: "Just", start: 6.35, end: 6.55 },
-        { text: "code", start: 6.55, end: 6.8 },
-        { text: "that", start: 6.8, end: 6.95 },
-        { text: "becomes", start: 6.95, end: 7.3 },
-        { text: "cinema.", start: 7.3, end: 7.7 },
-      ];
-
-      function normalizeWords(rawWords) {
-        return rawWords
-          .map(function (item) {
-            var text = String(item.word || item.text || "").trim();
-            var clean = text.toLowerCase().replace(/[^a-z]/g, "");
-            return {
-              text: text,
-              start: Math.max(0, Number(item.start) || 0),
-              end: Math.min(DURATION, Math.max(Number(item.start) || 0, Number(item.end) || 0)),
-              emoji: WORD_EMOJI[clean] || null,
-            };
-          })
-          .filter(function (word) {
-            return word.text.length > 0;
+      // IIFE: keep every template's runtime private to itself so two caption
+      // components pasted into one composition document can't clobber each
+      // other's hfAttach/hfBuild via shared script-scope names (boot is async,
+      // so collisions surface AFTER all scripts have executed).
+      (function () {
+        var HF_COMPOSITION_ID = "caption-emoji-pop";
+        var HF_ROOT_ID = "emoji-pop";
+        var HF_GROUP_SELECTOR = ".caption-group";
+
+        var HF_DEMO_DATA = {
+          version: 1,
+          segments: [
+            {
+              start: 0,
+              text: "Every great video starts with a single frame. HyperFrames lets you write HTML and render professional video. No timeline. No drag and drop. Just code that becomes cinema.",
+              words: [
+                { text: "Every", start: 0.0, end: 0.3 },
+                { text: "great", start: 0.3, end: 0.55 },
+                { text: "video", start: 0.55, end: 0.85 },
+                { text: "starts", start: 0.85, end: 1.1 },
+                { text: "with", start: 1.1, end: 1.25 },
+                { text: "a", start: 1.25, end: 1.35 },
+                { text: "single", start: 1.35, end: 1.65 },
+                { text: "frame.", start: 1.65, end: 2.0 },
+                { text: "HyperFrames", start: 2.1, end: 2.65 },
+                { text: "lets", start: 2.65, end: 2.85 },
+                { text: "you", start: 2.85, end: 2.95 },
+                { text: "write", start: 2.95, end: 3.15 },
+                { text: "HTML", start: 3.15, end: 3.55 },
+                { text: "and", start: 3.55, end: 3.65 },
+                { text: "render", start: 3.65, end: 3.95 },
+                { text: "professional", start: 3.95, end: 4.45 },
+                { text: "video.", start: 4.45, end: 4.8 },
+                { text: "No", start: 4.9, end: 5.05 },
+                { text: "timeline.", start: 5.05, end: 5.45 },
+                { text: "No", start: 5.5, end: 5.65 },
+                { text: "drag", start: 5.65, end: 5.85 },
+                { text: "and", start: 5.85, end: 5.95 },
+                { text: "drop.", start: 5.95, end: 6.25 },
+                { text: "Just", start: 6.35, end: 6.55 },
+                { text: "code", start: 6.55, end: 6.8 },
+                { text: "that", start: 6.8, end: 6.95 },
+                { text: "becomes", start: 6.95, end: 7.3 },
+                { text: "cinema.", start: 7.3, end: 7.7 },
+              ],
+            },
+          ],
+        };
+
+        /* ── HyperFrames caption-data runtime (shared across caption templates) ── */
+        var HF_CONTRACT_VERSION = 1;
+        var HF_DEFAULT_RESOLUTION = { width: 1920, height: 1080 };
+
+        function hfFlattenSegments(segments) {
+          var out = [];
+          (segments || []).forEach(function (seg) {
+            ((seg && seg.words) || []).forEach(function (w) {
+              var start = Math.max(0, Number(w.start) || 0);
+              out.push({
+                text: String(w.word || w.text || "").trim(),
+                start: start,
+                end: Math.max(start, Number(w.end) || 0),
+              });
+            });
           });
-      }
+          out.sort(function (a, b) {
+            return a.start - b.start;
+          });
+          return out.filter(function (w) {
+            return w.text.length > 0;
+          });
+        }
 
-      function seededRandom(seed) {
-        var x = Math.sin(seed * 9999) * 10000;
-        return x - Math.floor(x);
-      }
+        function hfDeriveDuration(words) {
+          var end = 0;
+          words.forEach(function (w) {
+            if (w.end > end) end = w.end;
+          });
+          return end;
+        }
 
-      function assignWordColors(words, groupIndex) {
-        return words.map(function (word, index) {
-          var clean = word.text.toLowerCase().replace(/[^a-z]/g, "");
-          if (KEYWORDS.has(clean)) {
-            var ci = Math.floor(seededRandom(groupIndex * 23 + index * 31) * ACCENT_COLORS.length);
-            return ACCENT_COLORS[ci];
+        function hfValidate(data) {
+          if (!data || typeof data !== "object") return { ok: false, reason: "not-an-object" };
+          if (data.version != null) {
+            // Number("v2") is NaN and NaN > x is always false — an explicit
+            // finite check keeps malformed versions from slipping past the gate.
+            var hfVersion = Number(data.version);
+            if (!Number.isFinite(hfVersion) || Math.floor(hfVersion) > HF_CONTRACT_VERSION) {
+              return { ok: false, reason: "unsupported-version" };
+            }
           }
-          if (TRANSITION_WORDS.has(clean)) return PRIMARY_COLOR;
-          var rand = seededRandom(groupIndex * 13 + index);
-          if (rand > 0.55) {
-            var ci2 = Math.floor(rand * ACCENT_COLORS.length) % ACCENT_COLORS.length;
-            return ACCENT_COLORS[ci2];
+          if (!Array.isArray(data.segments) || data.segments.length === 0) {
+            return { ok: false, reason: "no-segments" };
           }
-          return PRIMARY_COLOR;
-        });
-      }
+          if (data.displayMode != null && data.displayMode !== "full") {
+            return { ok: false, reason: "unsupported-displayMode" };
+          }
+          var words = hfFlattenSegments(data.segments);
+          if (words.length === 0) return { ok: false, reason: "no-words" };
+          return { ok: true, words: words, durationS: hfDeriveDuration(words) };
+        }
 
-      var _fitCanvas = document.createElement("canvas");
-      var _fitCtx = _fitCanvas.getContext("2d");
-      function fitFontSize(text, baseFontSize, fontWeight, fontFamily, maxWidth) {
-        var size = baseFontSize;
-        var minSize = Math.floor(baseFontSize * 0.45);
-        while (size > minSize) {
-          _fitCtx.font = fontWeight + " " + size + "px " + fontFamily;
-          if (_fitCtx.measureText(text).width <= maxWidth) return size;
-          size -= 2;
+        function hfApplyStageConfig(data, durationS) {
+          var res = (data && data.resolution) || HF_DEFAULT_RESOLUTION;
+          // Mirror the published validator's <=8192 bound defensively — the
+          // validator is an optional pre-flight, and an unbounded stage size
+          // would OOM render workers.
+          var W = Math.min(
+            8192,
+            Math.max(1, Math.round(Number(res.width) || HF_DEFAULT_RESOLUTION.width)),
+          );
+          var H = Math.min(
+            8192,
+            Math.max(1, Math.round(Number(res.height) || HF_DEFAULT_RESOLUTION.height)),
+          );
+          var root = document.getElementById(HF_ROOT_ID);
+          [document.documentElement, document.body, root].forEach(function (el) {
+            el.style.width = W + "px";
+            el.style.height = H + "px";
+          });
+          root.setAttribute("data-width", String(W));
+          root.setAttribute("data-height", String(H));
+          root.setAttribute("data-duration", String(durationS));
+          var brand = (data && data.brand) || {};
+          if (typeof brand.primaryColor === "string" && brand.primaryColor) {
+            root.style.setProperty("--hf-caption-primary", brand.primaryColor);
+          } else {
+            root.style.removeProperty("--hf-caption-primary");
+          }
+          if (typeof brand.accentColor === "string" && brand.accentColor) {
+            root.style.setProperty("--hf-caption-accent", brand.accentColor);
+          } else {
+            root.style.removeProperty("--hf-caption-accent");
+          }
+          return {
+            W: W,
+            H: H,
+            scaleX: W / 1920,
+            scaleY: H / 1080,
+            fontScale: Math.min(W, H) / 1080,
+          };
         }
-        return minSize;
-      }
 
-      var measureCanvas = document.createElement("canvas");
-      var measureContext = measureCanvas.getContext("2d");
+        function hfPublishStatus(status) {
+          window.__HF_CAPTION_STATUS = status;
+          document
+            .getElementById(HF_ROOT_ID)
+            .setAttribute("data-caption-status", status.ok ? "ok" : "failed");
+        }
 
-      function measureWord(word, fontSize) {
-        measureContext.font = "900 " + fontSize + "px Gabarito";
-        return measureContext.measureText(word.text.toUpperCase()).width * FONT_WIDTH_SAFETY;
-      }
+        function hfRunGate(words, durationS, failReason) {
+          if (failReason) {
+            hfPublishStatus({
+              ok: false,
+              present: false,
+              contained: false,
+              reason: failReason,
+              version: HF_CONTRACT_VERSION,
+              durationS: durationS || 0,
+            });
+            return;
+          }
+          var root = document.getElementById(HF_ROOT_ID);
+          var rootRect = root.getBoundingClientRect();
+          var groups = root.querySelectorAll(HF_GROUP_SELECTOR);
+          var present = false;
+          var contained = true;
+          var tokens = [];
+          words.forEach(function (w) {
+            var t = w.text.toLowerCase().replace(/[^a-z0-9]/g, "");
+            if (t) tokens.push(t);
+          });
+          groups.forEach(function (el) {
+            var prevOpacity = el.style.opacity;
+            var prevVisibility = el.style.visibility;
+            el.style.opacity = "1";
+            el.style.visibility = "visible";
+            var r = el.getBoundingClientRect();
+            if (r.width > 0 && r.height > 0) {
+              var text = (el.textContent || "").toLowerCase();
+              for (var i = 0; i < tokens.length; i++) {
+                if (text.indexOf(tokens[i]) !== -1) {
+                  present = true;
+                  break;
+                }
+              }
+              if (
+                r.left < rootRect.left - 1 ||
+                r.right > rootRect.right + 1 ||
+                r.top < rootRect.top - 1 ||
+                r.bottom > rootRect.bottom + 1
+              ) {
+                contained = false;
+              }
+            }
+            el.style.opacity = prevOpacity;
+            el.style.visibility = prevVisibility;
+          });
+          hfPublishStatus({
+            ok: present && contained,
+            present: present,
+            contained: contained,
+            version: HF_CONTRACT_VERSION,
+            durationS: durationS,
+          });
+        }
 
-      function measureLineWidth(words, fontSize) {
-        return words.reduce(function (total, word, index) {
-          return total + measureWord(word, fontSize) + (index ? WORD_SPACING : 0);
-        }, 0);
-      }
+        var HF_STOPWORDS = new Set([
+          "the",
+          "a",
+          "an",
+          "and",
+          "or",
+          "but",
+          "is",
+          "are",
+          "was",
+          "were",
+          "to",
+          "of",
+          "in",
+          "on",
+          "at",
+          "for",
+          "with",
+          "by",
+          "from",
+          "as",
+          "it",
+          "its",
+          "this",
+          "that",
+          "these",
+          "those",
+          "be",
+          "been",
+          "have",
+          "has",
+          "had",
+          "do",
+          "does",
+          "did",
+          "will",
+          "would",
+          "could",
+          "should",
+          "may",
+          "might",
+          "must",
+          "can",
+          "if",
+          "then",
+          "so",
+          "just",
+          "not",
+          "no",
+          "yes",
+          "up",
+          "out",
+          "about",
+          "into",
+          "over",
+          "after",
+          "before",
+          "your",
+          "you",
+          "our",
+          "we",
+          "they",
+          "them",
+          "their",
+          "there",
+          "here",
+          "when",
+          "what",
+          "which",
+          "who",
+          "how",
+          "all",
+          "any",
+          "some",
+          "more",
+          "most",
+          "other",
+          "than",
+          "too",
+          "very",
+          "also",
+          "because",
+        ]);
+
+        function hfIsEmphasisWord(text) {
+          var clean = String(text)
+            .toLowerCase()
+            .replace(/[^a-z]/g, "");
+          return clean.length >= 5 && !HF_STOPWORDS.has(clean);
+        }
 
-      function fitsLine(words) {
-        return measureLineWidth(words, CAPTION_FONT_SIZE) <= SAFE_ZONE_WIDTH;
-      }
+        var DURATION, SAFE_ZONE_WIDTH, CAPTION_FONT_SIZE, WORD_SPACING;
+        var MAX_WORDS_PER_GROUP = 3;
+        var PAUSE_THRESHOLD = 0.1;
+        var ENTRY_FRAMES = 4;
+        var EXIT_FRAMES = 3;
+        var FPS = 30;
+        var ENTRY_DURATION = ENTRY_FRAMES / FPS;
+        var EXIT_DURATION = EXIT_FRAMES / FPS;
+        var FONT_WIDTH_SAFETY = 1.14;
+        var PRIMARY_COLOR = "#FFFFFF";
+        var ACCENT_COLORS = ["#FF76FF", "#FF0002", "#B2F7FF"];
+        var hfPrimaryColor = PRIMARY_COLOR;
+        var hfAccentColors = ACCENT_COLORS;
+        var hfFontScale = 1;
+
+        // Emoji map for a generic keyword lexicon (not tied to the demo transcript)
+        var WORD_EMOJI = {
+          amazing: "🤩",
+          awesome: "🔥",
+          big: "🐘",
+          brain: "🧠",
+          build: "🛠️",
+          built: "🛠️",
+          celebrate: "🎉",
+          change: "🔄",
+          cinema: "🎥",
+          code: "⌨️",
+          customers: "🤝",
+          data: "📊",
+          dream: "💭",
+          easy: "👌",
+          fast: "⚡",
+          fire: "🔥",
+          frame: "🖼️",
+          free: "🎁",
+          fun: "🎈",
+          future: "🔮",
+          global: "🌍",
+          grow: "📈",
+          growth: "📈",
+          heart: "❤️",
+          huge: "🐘",
+          idea: "💡",
+          launch: "🚀",
+          learn: "📚",
+          love: "❤️",
+          magic: "✨",
+          money: "💰",
+          music: "🎵",
+          new: "✨",
+          party: "🎉",
+          perfect: "💯",
+          power: "💪",
+          professional: "✨",
+          rocket: "🚀",
+          save: "🛟",
+          saves: "🛟",
+          secret: "🤫",
+          smart: "🧠",
+          star: "⭐",
+          stop: "✋",
+          strong: "💪",
+          success: "🏆",
+          team: "👥",
+          time: "⏰",
+          today: "📅",
+          video: "📹",
+          win: "🏆",
+          world: "🌍",
+          wow: "😮",
+        };
 
-      function makeGroups(words) {
-        var groups = [];
-        var current = [];
-        words.forEach(function (word, index) {
-          var nextWord = words[index + 1];
-          var testGroup = current.concat([word]);
-          if (testGroup.length > MAX_WORDS_PER_GROUP || !fitsLine(testGroup)) {
-            if (current.length) groups.push(makeGroup(current, groups.length));
-            current = [word];
-            return;
-          }
-          current.push(word);
-          var punctuation = /[,.:!?]$/.test(word.text);
-          var pause = nextWord ? nextWord.start - word.end : 0;
-          if (
-            !nextWord ||
-            punctuation ||
-            pause >= PAUSE_THRESHOLD ||
-            current.length >= MAX_WORDS_PER_GROUP
-          ) {
-            groups.push(makeGroup(current, groups.length));
-            current = [];
-          }
-        });
-        if (current.length) groups.push(makeGroup(current, groups.length));
-        return groups;
-      }
+        function normalizeWords(rawWords) {
+          return rawWords
+            .map(function (item) {
+              var text = String(item.word || item.text || "").trim();
+              var clean = text.toLowerCase().replace(/[^a-z]/g, "");
+              return {
+                text: text,
+                start: Math.max(0, Number(item.start) || 0),
+                end: Math.min(DURATION, Math.max(Number(item.start) || 0, Number(item.end) || 0)),
+                emoji: WORD_EMOJI[clean] || null,
+              };
+            })
+            .filter(function (word) {
+              return word.text.length > 0;
+            });
+        }
+
+        function seededRandom(seed) {
+          var x = Math.sin(seed * 9999) * 10000;
+          return x - Math.floor(x);
+        }
 
-      function makeGroup(words, groupIndex) {
-        var colors = assignWordColors(words, groupIndex);
-        var emoji = null;
-        for (var i = 0; i < words.length; i++) {
-          if (words[i].emoji) {
-            emoji = words[i].emoji;
-            break;
+        function assignWordColors(words, groupIndex) {
+          return words.map(function (word, index) {
+            var clean = word.text.toLowerCase().replace(/[^a-z]/g, "");
+            if (hfIsEmphasisWord(word.text)) {
+              var ci = Math.floor(
+                seededRandom(groupIndex * 23 + index * 31) * hfAccentColors.length,
+              );
+              return hfAccentColors[ci];
+            }
+            if (HF_STOPWORDS.has(clean)) return hfPrimaryColor;
+            var rand = seededRandom(groupIndex * 13 + index);
+            if (rand > 0.55) {
+              var ci2 = Math.floor(rand * hfAccentColors.length) % hfAccentColors.length;
+              return hfAccentColors[ci2];
+            }
+            return hfPrimaryColor;
+          });
+        }
+
+        var _fitCanvas = document.createElement("canvas");
+        var _fitCtx = _fitCanvas.getContext("2d");
+        function fitFontSize(text, baseFontSize, fontWeight, fontFamily, maxWidth) {
+          var size = baseFontSize;
+          var minSize = Math.floor(baseFontSize * 0.45);
+          // minSize is a hard floor returned unverified below — self-heal
+          // accepts residual overflow at the floor (clipped by the stage)
+          // rather than shrinking below legibility.
+          while (size > minSize) {
+            _fitCtx.font = fontWeight + " " + size + "px " + fontFamily;
+            if (_fitCtx.measureText(text).width <= maxWidth) return size;
+            size -= 2;
           }
+          return minSize;
         }
-        return {
-          words: words.slice(),
-          colors: colors,
-          emoji: emoji,
-          start: words[0].start,
-          end: words[words.length - 1].end,
-        };
-      }
 
-      function shadowForColor(color) {
-        var hex = color.replace("#", "");
-        var r = parseInt(hex.slice(0, 2), 16);
-        var g = parseInt(hex.slice(2, 4), 16);
-        var b = parseInt(hex.slice(4, 6), 16);
-        return (
-          "0 4px 8px rgba(0,0,0,0.7), 0 0 2px rgba(" +
-          r +
-          "," +
-          g +
-          "," +
-          b +
-          ",1), 0 0 8px rgba(" +
-          r +
-          "," +
-          g +
-          "," +
-          b +
-          ",0.6)"
-        );
-      }
+        var measureCanvas = document.createElement("canvas");
+        var measureContext = measureCanvas.getContext("2d");
 
-      function buildCaptions(groups) {
-        var stage = document.getElementById("caption-stage");
-        groups.forEach(function (group, groupIndex) {
-          var groupText = group.words
-            .map(function (w) {
-              return w.text.toUpperCase();
-            })
-            .join(" ");
-          var computedSize = fitFontSize(
-            groupText,
-            CAPTION_FONT_SIZE,
-            "900",
-            "Gabarito",
-            SAFE_ZONE_WIDTH,
-          );
-          var groupEl = document.createElement("div");
-          groupEl.id = "caption-group-" + groupIndex;
-          groupEl.className = "caption-group";
-
-          if (group.emoji) {
-            var emojiEl = document.createElement("div");
-            emojiEl.className = "caption-emoji";
-            emojiEl.textContent = group.emoji;
-            groupEl.appendChild(emojiEl);
+        function measureWord(word, fontSize) {
+          measureContext.font = "900 " + fontSize + "px Gabarito";
+          return measureContext.measureText(word.text.toUpperCase()).width * FONT_WIDTH_SAFETY;
+        }
+
+        function measureLineWidth(words, fontSize) {
+          return words.reduce(function (total, word, index) {
+            return total + measureWord(word, fontSize) + (index ? WORD_SPACING : 0);
+          }, 0);
+        }
+
+        function fitsLine(words) {
+          return measureLineWidth(words, CAPTION_FONT_SIZE) <= SAFE_ZONE_WIDTH;
+        }
+
+        function makeGroups(words) {
+          var groups = [];
+          var current = [];
+          words.forEach(function (word, index) {
+            var nextWord = words[index + 1];
+            var testGroup = current.concat([word]);
+            if (testGroup.length > MAX_WORDS_PER_GROUP || !fitsLine(testGroup)) {
+              if (current.length) groups.push(makeGroup(current, groups.length));
+              current = [word];
+              return;
+            }
+            current.push(word);
+            var punctuation = /[,.:!?]$/.test(word.text);
+            var pause = nextWord ? nextWord.start - word.end : 0;
+            if (
+              !nextWord ||
+              punctuation ||
+              pause >= PAUSE_THRESHOLD ||
+              current.length >= MAX_WORDS_PER_GROUP
+            ) {
+              groups.push(makeGroup(current, groups.length));
+              current = [];
+            }
+          });
+          if (current.length) groups.push(makeGroup(current, groups.length));
+          return groups;
+        }
+
+        function makeGroup(words, groupIndex) {
+          var colors = assignWordColors(words, groupIndex);
+          var emoji = null;
+          for (var i = 0; i < words.length; i++) {
+            if (words[i].emoji) {
+              emoji = words[i].emoji;
+              break;
+            }
           }
+          return {
+            words: words.slice(),
+            colors: colors,
+            emoji: emoji,
+            start: words[0].start,
+            end: words[words.length - 1].end,
+          };
+        }
+
+        function shadowForColor(color) {
+          // color-mix handles ANY CSS color (hex of either length, rgb()/hsl(),
+          // named colors) — the old hex-pair slicing was why brand colors were
+          // gated behind a strict 6-digit regex, silently dropping payloads the
+          // sibling templates accept.
+          return (
+            "0 4px 8px rgba(0,0,0,0.7), 0 0 2px " +
+            color +
+            ", 0 0 8px color-mix(in srgb, " +
+            color +
+            " 60%, transparent)"
+          );
+        }
 
-          var lineEl = document.createElement("div");
-          lineEl.className = "caption-line";
-          group.words.forEach(function (word, wordIndex) {
-            var color = group.colors[wordIndex] || PRIMARY_COLOR;
-            var wordEl = document.createElement("span");
-            wordEl.className = "caption-word";
-            wordEl.textContent = word.text.toUpperCase();
-            wordEl.style.color = color;
-            wordEl.style.fontSize = computedSize + "px";
-            wordEl.style.textShadow = shadowForColor(color);
-            lineEl.appendChild(wordEl);
+        function buildCaptions(groups) {
+          var stage = document.getElementById("caption-stage");
+          groups.forEach(function (group, groupIndex) {
+            var groupText = group.words
+              .map(function (w) {
+                return w.text.toUpperCase();
+              })
+              .join(" ");
+            var computedSize = fitFontSize(
+              groupText,
+              CAPTION_FONT_SIZE,
+              "900",
+              "Gabarito",
+              SAFE_ZONE_WIDTH,
+            );
+            var groupEl = document.createElement("div");
+            groupEl.id = "caption-group-" + groupIndex;
+            groupEl.className = "caption-group";
+
+            if (group.emoji) {
+              var emojiEl = document.createElement("div");
+              emojiEl.className = "caption-emoji";
+              emojiEl.textContent = group.emoji;
+              emojiEl.style.fontSize = Math.round(56 * hfFontScale) + "px";
+              groupEl.appendChild(emojiEl);
+            }
+
+            var lineEl = document.createElement("div");
+            lineEl.className = "caption-line";
+            group.words.forEach(function (word, wordIndex) {
+              var color = group.colors[wordIndex] || hfPrimaryColor;
+              var wordEl = document.createElement("span");
+              wordEl.className = "caption-word";
+              wordEl.textContent = word.text.toUpperCase();
+              wordEl.style.color = color;
+              wordEl.style.fontSize = computedSize + "px";
+              wordEl.style.textShadow = shadowForColor(color);
+              lineEl.appendChild(wordEl);
+            });
+
+            groupEl.appendChild(lineEl);
+            stage.appendChild(groupEl);
           });
+        }
 
-          groupEl.appendChild(lineEl);
-          stage.appendChild(groupEl);
-        });
-      }
+        function hfTeardown() {
+          document.getElementById("caption-stage").innerHTML = "";
+        }
 
-      var WORDS = normalizeWords(TRANSCRIPT);
-      var GROUPS = makeGroups(WORDS);
-      buildCaptions(GROUPS);
-
-      window.__timelines = window.__timelines || {};
-      var tl = gsap.timeline({ paused: true });
-
-      var visibleStarts = GROUPS.map(function (group, groupIndex) {
-        var prev = GROUPS[groupIndex - 1];
-        var availableGap = prev ? Math.max(0, group.start - prev.end) : ENTRY_DURATION;
-        var entryLead = Math.min(ENTRY_DURATION, availableGap);
-        return Math.max(0, group.start - entryLead);
-      });
-
-      var allGroupEls = GROUPS.map(function (_, i) {
-        return document.getElementById("caption-group-" + i);
-      });
-
-      GROUPS.forEach(function (group, groupIndex) {
-        var groupEl = allGroupEls[groupIndex];
-        var visibleStart = visibleStarts[groupIndex];
-        var visibleEnd = groupIndex < GROUPS.length - 1 ? visibleStarts[groupIndex + 1] : DURATION;
-        var exitStart = Math.max(visibleStart, visibleEnd - EXIT_DURATION);
-
-        allGroupEls.forEach(function (otherEl, otherIndex) {
-          if (otherIndex !== groupIndex) tl.set(otherEl, { opacity: 0 }, visibleStart);
-        });
-
-        tl.set(groupEl, { opacity: 0, scaleX: 0.8, scaleY: 1 }, visibleStart);
-        tl.to(
-          groupEl,
-          { opacity: 1, scaleX: 1, duration: ENTRY_DURATION, ease: "power3.out", force3D: true },
-          visibleStart,
-        );
-        tl.to(
-          groupEl,
-          { scaleX: 0.75, opacity: 0.8, duration: EXIT_DURATION, ease: "power2.in", force3D: true },
-          exitStart,
-        );
-        tl.set(groupEl, { opacity: 0 }, visibleEnd);
-      });
-
-      window.__timelines["caption-emoji-pop"] = tl;
+        function hfBuild(words, layout, durationS) {
+          DURATION = durationS;
+          CAPTION_FONT_SIZE = Math.round(72 * layout.fontScale);
+          SAFE_ZONE_WIDTH = Math.round(1400 * layout.scaleX);
+          WORD_SPACING = Math.round(14 * layout.fontScale);
+          hfFontScale = layout.fontScale;
+
+          var stage = document.getElementById("caption-stage");
+          var stageHeight = Math.round(280 * layout.fontScale);
+          stage.style.width = SAFE_ZONE_WIDTH + "px";
+          stage.style.height = stageHeight + "px";
+          stage.style.bottom = Math.round(80 * layout.scaleY) + "px";
+
+          var rootEl = document.getElementById(HF_ROOT_ID);
+          // Any non-empty CSS color is honored (mirrors caption-pill-karaoke) —
+          // shadowForColor no longer needs parseable hex, so the old 6-digit
+          // gate (which silently dropped #fff / rgb() / named colors that the
+          // sibling templates accept) is gone.
+          var primary = getComputedStyle(rootEl).getPropertyValue("--hf-caption-primary").trim();
+          var accent = getComputedStyle(rootEl).getPropertyValue("--hf-caption-accent").trim();
+          hfPrimaryColor = primary || "#FFFFFF";
+          hfAccentColors = accent ? [accent] : ["#FF76FF", "#FF0002", "#B2F7FF"];
+
+          var WORDS = normalizeWords(words);
+          var GROUPS = makeGroups(WORDS);
+          buildCaptions(GROUPS);
+          GROUPS.forEach(function (_, i) {
+            var el = document.getElementById("caption-group-" + i);
+            el.style.width = SAFE_ZONE_WIDTH + "px";
+            el.style.height = stageHeight + "px";
+          });
+
+          var tl = gsap.timeline({ paused: true });
+
+          var visibleStarts = GROUPS.map(function (group, groupIndex) {
+            var prev = GROUPS[groupIndex - 1];
+            var availableGap = prev ? Math.max(0, group.start - prev.end) : ENTRY_DURATION;
+            var entryLead = Math.min(ENTRY_DURATION, availableGap);
+            return Math.max(0, group.start - entryLead);
+          });
+
+          var allGroupEls = GROUPS.map(function (_, i) {
+            return document.getElementById("caption-group-" + i);
+          });
+
+          GROUPS.forEach(function (group, groupIndex) {
+            var groupEl = allGroupEls[groupIndex];
+            var visibleStart = visibleStarts[groupIndex];
+            var visibleEnd =
+              groupIndex < GROUPS.length - 1 ? visibleStarts[groupIndex + 1] : DURATION;
+            var exitStart = Math.max(visibleStart, visibleEnd - EXIT_DURATION);
+
+            // Each group already owns its full opacity lifecycle (set 0 at its
+            // own visibleStart, animated to 1, then set back to 0 at its own
+            // visibleEnd below), and groups occupy non-overlapping windows, so
+            // explicitly hiding every OTHER group here was redundant and made
+            // timeline construction O(groups^2) — this collapsed under dense
+            // stress transcripts (many short groups). Removed; behavior is
+            // unchanged (verified against templates.test.ts).
+
+            tl.set(groupEl, { opacity: 0, scaleX: 0.8, scaleY: 1 }, visibleStart);
+            tl.to(
+              groupEl,
+              {
+                opacity: 1,
+                scaleX: 1,
+                duration: ENTRY_DURATION,
+                ease: "power3.out",
+                force3D: true,
+              },
+              visibleStart,
+            );
+            tl.to(
+              groupEl,
+              {
+                scaleX: 0.75,
+                opacity: 0.8,
+                duration: EXIT_DURATION,
+                ease: "power2.in",
+                force3D: true,
+              },
+              exitStart,
+            );
+            tl.set(groupEl, { opacity: 0 }, visibleEnd);
+          });
+
+          return tl;
+        }
+
+        var hfCurrentTimeline = null;
+
+        function hfAttach(data) {
+          var v = hfValidate(data);
+          if (!v.ok) {
+            hfRunGate([], 0, v.reason);
+            return;
+          }
+          if (hfCurrentTimeline) {
+            hfCurrentTimeline.kill();
+            hfCurrentTimeline = null;
+          }
+          hfTeardown();
+          var layout = hfApplyStageConfig(data, v.durationS);
+          var tl = hfBuild(v.words, layout, v.durationS);
+          tl.set({}, {}, v.durationS); // pin timeline length to the data-derived duration
+          // GSAP quirk (confirmed 3.14.2): a fresh timeline already reports position 0,
+          // so seek(0) is treated as a no-op and skips rendering .set() calls scheduled
+          // at t=0 — the first frame would show pre-timeline CSS defaults (usually
+          // hidden). render(time, suppressEvents, force) with force=true bypasses that.
+          tl.render(0, true, true);
+          hfCurrentTimeline = tl;
+          window.__timelines = window.__timelines || {};
+          window.__timelines[HF_COMPOSITION_ID] = tl;
+          hfRunGate(v.words, v.durationS, null);
+        }
+        window.__HF_CAPTION_ATTACH__ = hfAttach;
+
+        (function hfBoot() {
+          function start(data) {
+            var ready =
+              document.fonts && document.fonts.ready ? document.fonts.ready : Promise.resolve();
+            ready.then(function () {
+              // A manual window.__HF_CAPTION_ATTACH__ call that lands while the
+              // sibling fetch / fonts.ready are still pending must win — never
+              // clobber it with the late-arriving boot payload.
+              if (hfCurrentTimeline) return;
+              hfAttach(data);
+            });
+          }
+          if (window.__HF_CAPTION__) {
+            start(window.__HF_CAPTION__);
+            return;
+          }
+          fetch("./caption-data.json")
+            .then(function (r) {
+              return r.ok ? r.json() : null;
+            })
+            .catch(function () {
+              return null;
+            })
+            .then(function (json) {
+              start(json || HF_DEMO_DATA);
+            });
+        })();
+      })();
     </script>
   </body>
 </html>
diff --git a/registry/components/caption-highlight/caption-highlight.html b/registry/components/caption-highlight/caption-highlight.html
index 2617005887..2156930ceb 100644
--- a/registry/components/caption-highlight/caption-highlight.html
+++ b/registry/components/caption-highlight/caption-highlight.html
@@ -73,7 +73,7 @@
         font-weight: 800;
         font-size: 80px;
         text-transform: uppercase;
-        color: #ffffff;
+        color: var(--hf-caption-primary, #ffffff);
         display: inline-block;
         letter-spacing: 0.02em;
         line-height: 1;
@@ -86,7 +86,11 @@
       .hl-word-bg {
         position: absolute;
         inset: 0;
-        background: linear-gradient(135deg, #ff1745 0%, #df1238 100%);
+        background: linear-gradient(
+          135deg,
+          var(--hf-caption-accent, #ff1745) 0%,
+          color-mix(in srgb, var(--hf-caption-accent, #ff1745) 82%, #000) 100%
+        );
         border-radius: 10px;
         box-shadow: 0 12px 30px rgba(229, 20, 58, 0.32);
         opacity: 0;
@@ -117,6 +121,10 @@
 
     <script>
       (function () {
+        var HF_COMPOSITION_ID = "caption-highlight";
+        var HF_ROOT_ID = "highlight";
+        var HF_GROUP_SELECTOR = ".hl-group";
+
         window.__timelines = window.__timelines || {};
 
         var _fitCanvas = document.createElement("canvas");
@@ -124,6 +132,9 @@
         function fitFontSize(text, baseFontSize, fontWeight, fontFamily, maxWidth) {
           var size = baseFontSize;
           var minSize = Math.floor(baseFontSize * 0.45);
+          // minSize is a hard floor returned unverified below — self-heal
+          // accepts residual overflow at the floor (clipped by the stage)
+          // rather than shrinking below legibility.
           while (size > minSize) {
             _fitCtx.font = fontWeight + " " + size + "px " + fontFamily;
             if (_fitCtx.measureText(text).width <= maxWidth) return size;
@@ -132,129 +143,393 @@
           return minSize;
         }
 
-        var WORDS = [
-          { text: "Every", start: 0.0, end: 0.3 },
-          { text: "great", start: 0.3, end: 0.55 },
-          { text: "video", start: 0.55, end: 0.85 },
-          { text: "starts", start: 0.85, end: 1.1 },
-          { text: "with", start: 1.1, end: 1.25 },
-          { text: "a", start: 1.25, end: 1.35 },
-          { text: "single", start: 1.35, end: 1.65 },
-          { text: "frame.", start: 1.65, end: 2.0 },
-          { text: "HyperFrames", start: 2.1, end: 2.65 },
-          { text: "lets", start: 2.65, end: 2.85 },
-          { text: "you", start: 2.85, end: 2.95 },
-          { text: "write", start: 2.95, end: 3.15 },
-          { text: "HTML", start: 3.15, end: 3.55 },
-          { text: "and", start: 3.55, end: 3.65 },
-          { text: "render", start: 3.65, end: 3.95 },
-          { text: "professional", start: 3.95, end: 4.45 },
-          { text: "video.", start: 4.45, end: 4.8 },
-          { text: "No", start: 4.9, end: 5.05 },
-          { text: "timeline.", start: 5.05, end: 5.45 },
-          { text: "No", start: 5.5, end: 5.65 },
-          { text: "drag", start: 5.65, end: 5.85 },
-          { text: "and", start: 5.85, end: 5.95 },
-          { text: "drop.", start: 5.95, end: 6.25 },
-          { text: "Just", start: 6.35, end: 6.55 },
-          { text: "code", start: 6.55, end: 6.8 },
-          { text: "that", start: 6.8, end: 6.95 },
-          { text: "becomes", start: 6.95, end: 7.3 },
-          { text: "cinema.", start: 7.3, end: 7.7 },
-        ];
+        var HF_DEMO_DATA = {
+          version: 1,
+          segments: [
+            {
+              start: 0,
+              text: "Every great video starts with a single frame. HyperFrames lets you write HTML and render professional video. No timeline. No drag and drop. Just code that becomes cinema.",
+              words: [
+                { text: "Every", start: 0.0, end: 0.3 },
+                { text: "great", start: 0.3, end: 0.55 },
+                { text: "video", start: 0.55, end: 0.85 },
+                { text: "starts", start: 0.85, end: 1.1 },
+                { text: "with", start: 1.1, end: 1.25 },
+                { text: "a", start: 1.25, end: 1.35 },
+                { text: "single", start: 1.35, end: 1.65 },
+                { text: "frame.", start: 1.65, end: 2.0 },
+                { text: "HyperFrames", start: 2.1, end: 2.65 },
+                { text: "lets", start: 2.65, end: 2.85 },
+                { text: "you", start: 2.85, end: 2.95 },
+                { text: "write", start: 2.95, end: 3.15 },
+                { text: "HTML", start: 3.15, end: 3.55 },
+                { text: "and", start: 3.55, end: 3.65 },
+                { text: "render", start: 3.65, end: 3.95 },
+                { text: "professional", start: 3.95, end: 4.45 },
+                { text: "video.", start: 4.45, end: 4.8 },
+                { text: "No", start: 4.9, end: 5.05 },
+                { text: "timeline.", start: 5.05, end: 5.45 },
+                { text: "No", start: 5.5, end: 5.65 },
+                { text: "drag", start: 5.65, end: 5.85 },
+                { text: "and", start: 5.85, end: 5.95 },
+                { text: "drop.", start: 5.95, end: 6.25 },
+                { text: "Just", start: 6.35, end: 6.55 },
+                { text: "code", start: 6.55, end: 6.8 },
+                { text: "that", start: 6.8, end: 6.95 },
+                { text: "becomes", start: 6.95, end: 7.3 },
+                { text: "cinema.", start: 7.3, end: 7.7 },
+              ],
+            },
+          ],
+        };
 
-        var RAW_GROUPS = [
-          [0, 3],
-          [4, 7],
-          [8, 8],
-          [9, 12],
-          [13, 15],
-          [16, 16],
-          [17, 19],
-          [20, 22],
-          [23, 24],
-          [25, 27],
-        ];
-        var GROUPS = RAW_GROUPS.map(function (pair, gi) {
-          var ws = pair[0],
-            we = pair[1];
-          var nextStart = gi + 1 < RAW_GROUPS.length ? WORDS[RAW_GROUPS[gi + 1][0]].start : 8.0;
-          var gEnd = Math.min(WORDS[we].end + 0.5, nextStart - 0.05);
-          return { wordStart: ws, wordEnd: we, start: WORDS[ws].start, end: gEnd };
-        });
+        /* ── HyperFrames caption-data runtime (shared across caption templates) ── */
+        var HF_CONTRACT_VERSION = 1;
+        var HF_DEFAULT_RESOLUTION = { width: 1920, height: 1080 };
 
-        var container = document.getElementById("hl-container");
-        var tl = gsap.timeline({ paused: true });
+        function hfFlattenSegments(segments) {
+          var out = [];
+          (segments || []).forEach(function (seg) {
+            ((seg && seg.words) || []).forEach(function (w) {
+              var start = Math.max(0, Number(w.start) || 0);
+              out.push({
+                text: String(w.word || w.text || "").trim(),
+                start: start,
+                end: Math.max(start, Number(w.end) || 0),
+              });
+            });
+          });
+          out.sort(function (a, b) {
+            return a.start - b.start;
+          });
+          return out.filter(function (w) {
+            return w.text.length > 0;
+          });
+        }
 
-        GROUPS.forEach(function (g, gi) {
-          var groupWords = WORDS.slice(g.wordStart, g.wordEnd + 1);
-          var grp = document.createElement("div");
-          grp.className = "hl-group";
-          grp.id = "hl-grp-" + gi;
+        function hfDeriveDuration(words) {
+          var end = 0;
+          words.forEach(function (w) {
+            if (w.end > end) end = w.end;
+          });
+          return end;
+        }
 
-          var groupText = groupWords
-            .map(function (w) {
-              return w.text.toUpperCase();
-            })
-            .join(" ");
-          var computedSize = fitFontSize(groupText, 80, "800", "Montserrat", 1620);
+        function hfValidate(data) {
+          if (!data || typeof data !== "object") return { ok: false, reason: "not-an-object" };
+          if (data.version != null) {
+            // Number("v2") is NaN and NaN > x is always false — an explicit
+            // finite check keeps malformed versions from slipping past the gate.
+            var hfVersion = Number(data.version);
+            if (!Number.isFinite(hfVersion) || Math.floor(hfVersion) > HF_CONTRACT_VERSION) {
+              return { ok: false, reason: "unsupported-version" };
+            }
+          }
+          if (!Array.isArray(data.segments) || data.segments.length === 0) {
+            return { ok: false, reason: "no-segments" };
+          }
+          if (data.displayMode != null && data.displayMode !== "full") {
+            return { ok: false, reason: "unsupported-displayMode" };
+          }
+          var words = hfFlattenSegments(data.segments);
+          if (words.length === 0) return { ok: false, reason: "no-words" };
+          return { ok: true, words: words, durationS: hfDeriveDuration(words) };
+        }
 
-          groupWords.forEach(function (w, i) {
-            var wi = g.wordStart + i;
-            var wordEl = document.createElement("span");
-            wordEl.className = "hl-word";
-            wordEl.id = "hl-w-" + wi;
-            wordEl.style.fontSize = computedSize + "px";
+        function hfApplyStageConfig(data, durationS) {
+          var res = (data && data.resolution) || HF_DEFAULT_RESOLUTION;
+          // Mirror the published validator's <=8192 bound defensively — the
+          // validator is an optional pre-flight, and an unbounded stage size
+          // would OOM render workers.
+          var W = Math.min(
+            8192,
+            Math.max(1, Math.round(Number(res.width) || HF_DEFAULT_RESOLUTION.width)),
+          );
+          var H = Math.min(
+            8192,
+            Math.max(1, Math.round(Number(res.height) || HF_DEFAULT_RESOLUTION.height)),
+          );
+          var root = document.getElementById(HF_ROOT_ID);
+          [document.documentElement, document.body, root].forEach(function (el) {
+            el.style.width = W + "px";
+            el.style.height = H + "px";
+          });
+          root.setAttribute("data-width", String(W));
+          root.setAttribute("data-height", String(H));
+          root.setAttribute("data-duration", String(durationS));
+          var brand = (data && data.brand) || {};
+          if (typeof brand.primaryColor === "string" && brand.primaryColor) {
+            root.style.setProperty("--hf-caption-primary", brand.primaryColor);
+          } else {
+            root.style.removeProperty("--hf-caption-primary");
+          }
+          if (typeof brand.accentColor === "string" && brand.accentColor) {
+            root.style.setProperty("--hf-caption-accent", brand.accentColor);
+          } else {
+            root.style.removeProperty("--hf-caption-accent");
+          }
+          return {
+            W: W,
+            H: H,
+            scaleX: W / 1920,
+            scaleY: H / 1080,
+            fontScale: Math.min(W, H) / 1080,
+          };
+        }
 
-            var bgEl = document.createElement("span");
-            bgEl.className = "hl-word-bg";
-            bgEl.id = "hl-bg-" + wi;
+        function hfPublishStatus(status) {
+          window.__HF_CAPTION_STATUS = status;
+          document
+            .getElementById(HF_ROOT_ID)
+            .setAttribute("data-caption-status", status.ok ? "ok" : "failed");
+        }
 
-            var textEl = document.createElement("span");
-            textEl.className = "hl-word-text";
-            textEl.textContent = w.text.toUpperCase();
+        function hfRunGate(words, durationS, failReason) {
+          if (failReason) {
+            hfPublishStatus({
+              ok: false,
+              present: false,
+              contained: false,
+              reason: failReason,
+              version: HF_CONTRACT_VERSION,
+              durationS: durationS || 0,
+            });
+            return;
+          }
+          var root = document.getElementById(HF_ROOT_ID);
+          var rootRect = root.getBoundingClientRect();
+          var groups = root.querySelectorAll(HF_GROUP_SELECTOR);
+          var present = false;
+          var contained = true;
+          var tokens = [];
+          words.forEach(function (w) {
+            var t = w.text.toLowerCase().replace(/[^a-z0-9]/g, "");
+            if (t) tokens.push(t);
+          });
+          groups.forEach(function (el) {
+            var prevOpacity = el.style.opacity;
+            var prevVisibility = el.style.visibility;
+            el.style.opacity = "1";
+            el.style.visibility = "visible";
+            var r = el.getBoundingClientRect();
+            if (r.width > 0 && r.height > 0) {
+              var text = (el.textContent || "").toLowerCase();
+              for (var i = 0; i < tokens.length; i++) {
+                if (text.indexOf(tokens[i]) !== -1) {
+                  present = true;
+                  break;
+                }
+              }
+              if (
+                r.left < rootRect.left - 1 ||
+                r.right > rootRect.right + 1 ||
+                r.top < rootRect.top - 1 ||
+                r.bottom > rootRect.bottom + 1
+              ) {
+                contained = false;
+              }
+            }
+            el.style.opacity = prevOpacity;
+            el.style.visibility = prevVisibility;
+          });
+          hfPublishStatus({
+            ok: present && contained,
+            present: present,
+            contained: contained,
+            version: HF_CONTRACT_VERSION,
+            durationS: durationS,
+          });
+        }
+
+        var MAX_WORDS_PER_GROUP = 4;
+        var PAUSE_THRESHOLD = 0.1;
 
-            wordEl.appendChild(bgEl);
-            wordEl.appendChild(textEl);
-            grp.appendChild(wordEl);
+        function hfMakeGroups(words, fontPx, safeWidth, durationS) {
+          var raw = [];
+          var current = [];
+          function fits(ws) {
+            var text = ws
+              .map(function (w) {
+                return w.text.toUpperCase();
+              })
+              .join(" ");
+            _fitCtx.font = "800 " + fontPx + "px Montserrat";
+            // 1.6× headroom: fitFontSize can shrink to 45% of base
+            return _fitCtx.measureText(text).width <= safeWidth * 1.6;
+          }
+          words.forEach(function (w, i) {
+            var next = words[i + 1];
+            var test = current.concat([w]);
+            if (test.length > MAX_WORDS_PER_GROUP || !fits(test)) {
+              if (current.length) raw.push(current);
+              current = [w];
+            } else {
+              current.push(w);
+            }
+            var punctuation = /[,.:!?]$/.test(w.text);
+            var pause = next ? next.start - w.end : Infinity;
+            if (
+              current.length &&
+              (punctuation ||
+                pause >= PAUSE_THRESHOLD ||
+                current.length >= MAX_WORDS_PER_GROUP ||
+                !next)
+            ) {
+              raw.push(current);
+              current = [];
+            }
+          });
+          if (current.length) raw.push(current);
+          return raw.map(function (ws, gi) {
+            var nextStart = gi + 1 < raw.length ? raw[gi + 1][0].start : durationS;
+            return {
+              words: ws,
+              start: ws[0].start,
+              end: Math.min(
+                ws[ws.length - 1].end + 0.5,
+                Math.max(ws[0].start + 0.2, nextStart - 0.05),
+              ),
+            };
           });
+        }
 
-          container.appendChild(grp);
+        function hfTeardown() {
+          document.getElementById("hl-container").innerHTML = "";
+        }
 
-          tl.set(grp, { visibility: "visible" }, g.start);
-          tl.fromTo(
-            grp,
-            { opacity: 0 },
-            { opacity: 1, duration: 0.12, ease: "power2.out" },
-            g.start,
-          );
+        function hfBuild(words, layout, durationS) {
+          var fontPx = Math.round(80 * layout.fontScale);
+          var safeWidth = Math.round(1620 * layout.scaleX);
+          var container = document.getElementById("hl-container");
+          var groups = hfMakeGroups(words, fontPx, safeWidth, durationS);
+          var tl = gsap.timeline({ paused: true });
+          var wordCounter = 0;
 
-          groupWords.forEach(function (w, i) {
-            var wi = g.wordStart + i;
-            var bgEl = document.getElementById("hl-bg-" + wi);
-            var wordEl = document.getElementById("hl-w-" + wi);
+          groups.forEach(function (g, gi) {
+            var grp = document.createElement("div");
+            grp.className = "hl-group";
+            grp.id = "hl-grp-" + gi;
+            grp.style.bottom = Math.round(140 * layout.scaleY) + "px";
+            grp.style.paddingLeft = Math.round(100 * layout.scaleX) + "px";
+            grp.style.paddingRight = Math.round(100 * layout.scaleX) + "px";
 
-            tl.to(bgEl, { opacity: 1, scaleX: 1, duration: 0.15, ease: "power2.out" }, w.start);
-            tl.to(
-              wordEl,
-              { filter: "brightness(1.05)", duration: 0.08, ease: "power2.out" },
-              w.start,
+            var groupText = g.words
+              .map(function (w) {
+                return w.text.toUpperCase();
+              })
+              .join(" ");
+            var computedSize = fitFontSize(groupText, fontPx, "800", "Montserrat", safeWidth);
+
+            var ids = [];
+            g.words.forEach(function (w) {
+              var wi = wordCounter++;
+              ids.push(wi);
+              var wordEl = document.createElement("span");
+              wordEl.className = "hl-word";
+              wordEl.id = "hl-w-" + wi;
+              wordEl.style.fontSize = computedSize + "px";
+              var bgEl = document.createElement("span");
+              bgEl.className = "hl-word-bg";
+              bgEl.id = "hl-bg-" + wi;
+              var textEl = document.createElement("span");
+              textEl.className = "hl-word-text";
+              textEl.textContent = w.text.toUpperCase();
+              wordEl.appendChild(bgEl);
+              wordEl.appendChild(textEl);
+              grp.appendChild(wordEl);
+            });
+            container.appendChild(grp);
+
+            tl.set(grp, { visibility: "visible" }, g.start);
+            tl.fromTo(
+              grp,
+              { opacity: 0 },
+              { opacity: 1, duration: 0.12, ease: "power2.out" },
+              g.start,
             );
+            g.words.forEach(function (w, i) {
+              var bgEl = document.getElementById("hl-bg-" + ids[i]);
+              var wordEl = document.getElementById("hl-w-" + ids[i]);
+              tl.to(bgEl, { opacity: 1, scaleX: 1, duration: 0.15, ease: "power2.out" }, w.start);
+              tl.to(
+                wordEl,
+                { filter: "brightness(1.05)", duration: 0.08, ease: "power2.out" },
+                w.start,
+              );
+              tl.to(
+                wordEl,
+                { filter: "brightness(1)", duration: 0.16, ease: "power2.out" },
+                w.start + 0.08,
+              );
+              tl.to(bgEl, { opacity: 0, scaleX: 1.02, duration: 0.1, ease: "power2.in" }, w.end);
+              tl.set(bgEl, { scaleX: 0 }, w.end + 0.1);
+            });
             tl.to(
-              wordEl,
-              { filter: "brightness(1)", duration: 0.16, ease: "power2.out" },
-              w.start + 0.08,
+              grp,
+              { opacity: 0, duration: 0.1, ease: "power2.in" },
+              Math.max(g.start, g.end - 0.1),
             );
-            tl.to(bgEl, { opacity: 0, scaleX: 1.02, duration: 0.1, ease: "power2.in" }, w.end);
-            tl.set(bgEl, { scaleX: 0 }, w.end + 0.1);
+            tl.set(grp, { opacity: 0, visibility: "hidden" }, g.end);
           });
 
-          tl.to(grp, { opacity: 0, duration: 0.1, ease: "power2.in" }, g.end - 0.1);
-          tl.set(grp, { opacity: 0, visibility: "hidden" }, g.end);
-        });
+          return tl;
+        }
+
+        var hfCurrentTimeline = null;
+
+        function hfAttach(data) {
+          var v = hfValidate(data);
+          if (!v.ok) {
+            hfRunGate([], 0, v.reason);
+            return;
+          }
+          if (hfCurrentTimeline) {
+            hfCurrentTimeline.kill();
+            hfCurrentTimeline = null;
+          }
+          hfTeardown();
+          var layout = hfApplyStageConfig(data, v.durationS);
+          var tl = hfBuild(v.words, layout, v.durationS);
+          tl.set({}, {}, v.durationS); // pin timeline length to the data-derived duration
+          // GSAP quirk (confirmed 3.14.2): a fresh timeline already reports position 0,
+          // so seek(0) is treated as a no-op and skips rendering .set() calls scheduled
+          // at t=0 — the first frame would show pre-timeline CSS defaults (usually
+          // hidden). render(time, suppressEvents, force) with force=true bypasses that.
+          tl.render(0, true, true);
+          hfCurrentTimeline = tl;
+          window.__timelines = window.__timelines || {};
+          window.__timelines[HF_COMPOSITION_ID] = tl;
+          hfRunGate(v.words, v.durationS, null);
+        }
+        window.__HF_CAPTION_ATTACH__ = hfAttach;
 
-        tl.seek(0);
-        window.__timelines["caption-highlight"] = tl;
+        (function hfBoot() {
+          function start(data) {
+            var ready =
+              document.fonts && document.fonts.ready ? document.fonts.ready : Promise.resolve();
+            ready.then(function () {
+              // A manual window.__HF_CAPTION_ATTACH__ call that lands while the
+              // sibling fetch / fonts.ready are still pending must win — never
+              // clobber it with the late-arriving boot payload.
+              if (hfCurrentTimeline) return;
+              hfAttach(data);
+            });
+          }
+          if (window.__HF_CAPTION__) {
+            start(window.__HF_CAPTION__);
+            return;
+          }
+          fetch("./caption-data.json")
+            .then(function (r) {
+              return r.ok ? r.json() : null;
+            })
+            .catch(function () {
+              return null;
+            })
+            .then(function (json) {
+              start(json || HF_DEMO_DATA);
+            });
+        })();
       })();
     </script>
   </body>
diff --git a/registry/components/caption-pill-karaoke/caption-pill-karaoke.html b/registry/components/caption-pill-karaoke/caption-pill-karaoke.html
index 06b5a4ac2c..5e19c8ed47 100644
--- a/registry/components/caption-pill-karaoke/caption-pill-karaoke.html
+++ b/registry/components/caption-pill-karaoke/caption-pill-karaoke.html
@@ -131,252 +131,514 @@
     </div>
 
     <script>
-      var DURATION = 8;
-      var SAFE_ZONE_WIDTH = 1400;
-      var PILL_MAX_WIDTH = 1400;
-      var PILL_MIN_PADDING_X = 30;
-      var PILL_MAX_PADDING_X = 60;
-      var FONT_WIDTH_SAFETY = 1.18;
-      var FONT_FAMILY = "Poppins";
-      var FONT_WEIGHT = "700";
-      var BASE_FONT_SIZE = 72;
-      var MIN_FONT_SIZE = 52;
-      var MAX_WORDS_PER_GROUP = 4;
-      var WORD_SPACING = 16;
-      var PAUSE_THRESHOLD = 0.1;
-      var GROUP_END_BUFFER = 0.3;
-      var COLOR_INACTIVE = "#A6A6A6";
-      var COLOR_ACTIVE = "#1C1E1D";
-      var COLOR_FADE_DURATION = 0.1;
-      var WORD_FADE_LEAD = 0.05;
-
-      var TRANSCRIPT = [
-        { text: "Every", start: 0.0, end: 0.3 },
-        { text: "great", start: 0.3, end: 0.55 },
-        { text: "video", start: 0.55, end: 0.85 },
-        { text: "starts", start: 0.85, end: 1.1 },
-        { text: "with", start: 1.1, end: 1.25 },
-        { text: "a", start: 1.25, end: 1.35 },
-        { text: "single", start: 1.35, end: 1.65 },
-        { text: "frame.", start: 1.65, end: 2.0 },
-        { text: "HyperFrames", start: 2.1, end: 2.65 },
-        { text: "lets", start: 2.65, end: 2.85 },
-        { text: "you", start: 2.85, end: 2.95 },
-        { text: "write", start: 2.95, end: 3.15 },
-        { text: "HTML", start: 3.15, end: 3.55 },
-        { text: "and", start: 3.55, end: 3.65 },
-        { text: "render", start: 3.65, end: 3.95 },
-        { text: "professional", start: 3.95, end: 4.45 },
-        { text: "video.", start: 4.45, end: 4.8 },
-        { text: "No", start: 4.9, end: 5.05 },
-        { text: "timeline.", start: 5.05, end: 5.45 },
-        { text: "No", start: 5.5, end: 5.65 },
-        { text: "drag", start: 5.65, end: 5.85 },
-        { text: "and", start: 5.85, end: 5.95 },
-        { text: "drop.", start: 5.95, end: 6.25 },
-        { text: "Just", start: 6.35, end: 6.55 },
-        { text: "code", start: 6.55, end: 6.8 },
-        { text: "that", start: 6.8, end: 6.95 },
-        { text: "becomes", start: 6.95, end: 7.3 },
-        { text: "cinema.", start: 7.3, end: 7.7 },
-      ];
-
-      function normalizeWords(rawWords) {
-        return rawWords
-          .map(function (item) {
-            var text = String(item.word || item.text || "").trim();
-            return {
-              text: text,
-              start: Math.max(0, Number(item.start) || 0),
-              end: Math.min(DURATION, Math.max(Number(item.start) || 0, Number(item.end) || 0)),
-            };
-          })
-          .filter(function (w) {
+      // IIFE: keep every template's runtime private to itself so two caption
+      // components pasted into one composition document can't clobber each
+      // other's hfAttach/hfBuild via shared script-scope names (boot is async,
+      // so collisions surface AFTER all scripts have executed).
+      (function () {
+        var HF_COMPOSITION_ID = "caption-pill-karaoke";
+        var HF_ROOT_ID = "pill-karaoke";
+        var HF_GROUP_SELECTOR = ".caption-group";
+
+        var HF_DEMO_DATA = {
+          version: 1,
+          segments: [
+            {
+              start: 0,
+              text: "Every great video starts with a single frame. HyperFrames lets you write HTML and render professional video. No timeline. No drag and drop. Just code that becomes cinema.",
+              words: [
+                { text: "Every", start: 0.0, end: 0.3 },
+                { text: "great", start: 0.3, end: 0.55 },
+                { text: "video", start: 0.55, end: 0.85 },
+                { text: "starts", start: 0.85, end: 1.1 },
+                { text: "with", start: 1.1, end: 1.25 },
+                { text: "a", start: 1.25, end: 1.35 },
+                { text: "single", start: 1.35, end: 1.65 },
+                { text: "frame.", start: 1.65, end: 2.0 },
+                { text: "HyperFrames", start: 2.1, end: 2.65 },
+                { text: "lets", start: 2.65, end: 2.85 },
+                { text: "you", start: 2.85, end: 2.95 },
+                { text: "write", start: 2.95, end: 3.15 },
+                { text: "HTML", start: 3.15, end: 3.55 },
+                { text: "and", start: 3.55, end: 3.65 },
+                { text: "render", start: 3.65, end: 3.95 },
+                { text: "professional", start: 3.95, end: 4.45 },
+                { text: "video.", start: 4.45, end: 4.8 },
+                { text: "No", start: 4.9, end: 5.05 },
+                { text: "timeline.", start: 5.05, end: 5.45 },
+                { text: "No", start: 5.5, end: 5.65 },
+                { text: "drag", start: 5.65, end: 5.85 },
+                { text: "and", start: 5.85, end: 5.95 },
+                { text: "drop.", start: 5.95, end: 6.25 },
+                { text: "Just", start: 6.35, end: 6.55 },
+                { text: "code", start: 6.55, end: 6.8 },
+                { text: "that", start: 6.8, end: 6.95 },
+                { text: "becomes", start: 6.95, end: 7.3 },
+                { text: "cinema.", start: 7.3, end: 7.7 },
+              ],
+            },
+          ],
+        };
+
+        /* ── HyperFrames caption-data runtime (shared across caption templates) ── */
+        var HF_CONTRACT_VERSION = 1;
+        var HF_DEFAULT_RESOLUTION = { width: 1920, height: 1080 };
+
+        function hfFlattenSegments(segments) {
+          var out = [];
+          (segments || []).forEach(function (seg) {
+            ((seg && seg.words) || []).forEach(function (w) {
+              var start = Math.max(0, Number(w.start) || 0);
+              out.push({
+                text: String(w.word || w.text || "").trim(),
+                start: start,
+                end: Math.max(start, Number(w.end) || 0),
+              });
+            });
+          });
+          out.sort(function (a, b) {
+            return a.start - b.start;
+          });
+          return out.filter(function (w) {
             return w.text.length > 0;
           });
-      }
+        }
 
-      var measureCanvas = document.createElement("canvas");
-      var measureContext = measureCanvas.getContext("2d");
+        function hfDeriveDuration(words) {
+          var end = 0;
+          words.forEach(function (w) {
+            if (w.end > end) end = w.end;
+          });
+          return end;
+        }
 
-      function measureWordWidth(text, fontSize) {
-        measureContext.font = FONT_WEIGHT + " " + fontSize + "px " + FONT_FAMILY;
-        return measureContext.measureText(text).width * FONT_WIDTH_SAFETY;
-      }
+        function hfValidate(data) {
+          if (!data || typeof data !== "object") return { ok: false, reason: "not-an-object" };
+          if (data.version != null) {
+            // Number("v2") is NaN and NaN > x is always false — an explicit
+            // finite check keeps malformed versions from slipping past the gate.
+            var hfVersion = Number(data.version);
+            if (!Number.isFinite(hfVersion) || Math.floor(hfVersion) > HF_CONTRACT_VERSION) {
+              return { ok: false, reason: "unsupported-version" };
+            }
+          }
+          if (!Array.isArray(data.segments) || data.segments.length === 0) {
+            return { ok: false, reason: "no-segments" };
+          }
+          if (data.displayMode != null && data.displayMode !== "full") {
+            return { ok: false, reason: "unsupported-displayMode" };
+          }
+          var words = hfFlattenSegments(data.segments);
+          if (words.length === 0) return { ok: false, reason: "no-words" };
+          return { ok: true, words: words, durationS: hfDeriveDuration(words) };
+        }
 
-      function measureLineWidth(words, fontSize) {
-        return words.reduce(function (total, word, index) {
-          return (
-            total + measureWordWidth(word.text.toLowerCase(), fontSize) + (index ? WORD_SPACING : 0)
+        function hfApplyStageConfig(data, durationS) {
+          var res = (data && data.resolution) || HF_DEFAULT_RESOLUTION;
+          // Mirror the published validator's <=8192 bound defensively — the
+          // validator is an optional pre-flight, and an unbounded stage size
+          // would OOM render workers.
+          var W = Math.min(
+            8192,
+            Math.max(1, Math.round(Number(res.width) || HF_DEFAULT_RESOLUTION.width)),
           );
-        }, 0);
-      }
+          var H = Math.min(
+            8192,
+            Math.max(1, Math.round(Number(res.height) || HF_DEFAULT_RESOLUTION.height)),
+          );
+          var root = document.getElementById(HF_ROOT_ID);
+          [document.documentElement, document.body, root].forEach(function (el) {
+            el.style.width = W + "px";
+            el.style.height = H + "px";
+          });
+          root.setAttribute("data-width", String(W));
+          root.setAttribute("data-height", String(H));
+          root.setAttribute("data-duration", String(durationS));
+          var brand = (data && data.brand) || {};
+          if (typeof brand.primaryColor === "string" && brand.primaryColor) {
+            root.style.setProperty("--hf-caption-primary", brand.primaryColor);
+          } else {
+            root.style.removeProperty("--hf-caption-primary");
+          }
+          if (typeof brand.accentColor === "string" && brand.accentColor) {
+            root.style.setProperty("--hf-caption-accent", brand.accentColor);
+          } else {
+            root.style.removeProperty("--hf-caption-accent");
+          }
+          return {
+            W: W,
+            H: H,
+            scaleX: W / 1920,
+            scaleY: H / 1080,
+            fontScale: Math.min(W, H) / 1080,
+          };
+        }
 
-      function splitLinesForGroup(words, fontSize) {
-        var maxLineWidth = PILL_MAX_WIDTH - PILL_MIN_PADDING_X * 2;
-        if (
-          words.some(function (w) {
-            return measureWordWidth(w.text.toLowerCase(), fontSize) > maxLineWidth;
-          })
-        ) {
-          return null;
+        function hfPublishStatus(status) {
+          window.__HF_CAPTION_STATUS = status;
+          document
+            .getElementById(HF_ROOT_ID)
+            .setAttribute("data-caption-status", status.ok ? "ok" : "failed");
         }
-        if (measureLineWidth(words, fontSize) <= maxLineWidth) return [words];
-        var bestSplit = null;
-        var bestImbalance = Infinity;
-        for (var split = 1; split < words.length; split++) {
-          var firstLine = words.slice(0, split);
-          var secondLine = words.slice(split);
-          var firstWidth = measureLineWidth(firstLine, fontSize);
-          var secondWidth = measureLineWidth(secondLine, fontSize);
-          if (firstWidth <= maxLineWidth && secondWidth <= maxLineWidth) {
-            var imbalance = Math.abs(firstWidth - secondWidth);
-            if (imbalance < bestImbalance) {
-              bestSplit = [firstLine, secondLine];
-              bestImbalance = imbalance;
+
+        function hfRunGate(words, durationS, failReason) {
+          if (failReason) {
+            hfPublishStatus({
+              ok: false,
+              present: false,
+              contained: false,
+              reason: failReason,
+              version: HF_CONTRACT_VERSION,
+              durationS: durationS || 0,
+            });
+            return;
+          }
+          var root = document.getElementById(HF_ROOT_ID);
+          var rootRect = root.getBoundingClientRect();
+          var groups = root.querySelectorAll(HF_GROUP_SELECTOR);
+          var present = false;
+          var contained = true;
+          var tokens = [];
+          words.forEach(function (w) {
+            var t = w.text.toLowerCase().replace(/[^a-z0-9]/g, "");
+            if (t) tokens.push(t);
+          });
+          groups.forEach(function (el) {
+            var prevOpacity = el.style.opacity;
+            var prevVisibility = el.style.visibility;
+            el.style.opacity = "1";
+            el.style.visibility = "visible";
+            var r = el.getBoundingClientRect();
+            if (r.width > 0 && r.height > 0) {
+              var text = (el.textContent || "").toLowerCase();
+              for (var i = 0; i < tokens.length; i++) {
+                if (text.indexOf(tokens[i]) !== -1) {
+                  present = true;
+                  break;
+                }
+              }
+              if (
+                r.left < rootRect.left - 1 ||
+                r.right > rootRect.right + 1 ||
+                r.top < rootRect.top - 1 ||
+                r.bottom > rootRect.bottom + 1
+              ) {
+                contained = false;
+              }
             }
+            el.style.opacity = prevOpacity;
+            el.style.visibility = prevVisibility;
+          });
+          hfPublishStatus({
+            ok: present && contained,
+            present: present,
+            contained: contained,
+            version: HF_CONTRACT_VERSION,
+            durationS: durationS,
+          });
+        }
+
+        var DURATION, SAFE_ZONE_WIDTH, PILL_MAX_WIDTH, BASE_FONT_SIZE, MIN_FONT_SIZE, WORD_SPACING;
+        var PILL_MIN_PADDING_X = 30;
+        var PILL_MAX_PADDING_X = 60;
+        var FONT_WIDTH_SAFETY = 1.18;
+        var FONT_FAMILY = "Poppins";
+        var FONT_WEIGHT = "700";
+        var MAX_WORDS_PER_GROUP = 4;
+        var PAUSE_THRESHOLD = 0.1;
+        var GROUP_END_BUFFER = 0.3;
+        var COLOR_INACTIVE = "#A6A6A6";
+        var COLOR_ACTIVE = "#1C1E1D";
+        var hfColorActive = COLOR_ACTIVE;
+        var COLOR_FADE_DURATION = 0.1;
+        var WORD_FADE_LEAD = 0.05;
+
+        function normalizeWords(rawWords) {
+          return rawWords
+            .map(function (item) {
+              var text = String(item.word || item.text || "").trim();
+              return {
+                text: text,
+                start: Math.max(0, Number(item.start) || 0),
+                end: Math.min(DURATION, Math.max(Number(item.start) || 0, Number(item.end) || 0)),
+              };
+            })
+            .filter(function (w) {
+              return w.text.length > 0;
+            });
+        }
+
+        var measureCanvas = document.createElement("canvas");
+        var measureContext = measureCanvas.getContext("2d");
+
+        function measureWordWidth(text, fontSize) {
+          measureContext.font = FONT_WEIGHT + " " + fontSize + "px " + FONT_FAMILY;
+          return measureContext.measureText(text).width * FONT_WIDTH_SAFETY;
+        }
+
+        function measureLineWidth(words, fontSize) {
+          return words.reduce(function (total, word, index) {
+            return (
+              total +
+              measureWordWidth(word.text.toLowerCase(), fontSize) +
+              (index ? WORD_SPACING : 0)
+            );
+          }, 0);
+        }
+
+        function splitLinesForGroup(words, fontSize) {
+          var maxLineWidth = PILL_MAX_WIDTH - PILL_MIN_PADDING_X * 2;
+          if (
+            words.some(function (w) {
+              return measureWordWidth(w.text.toLowerCase(), fontSize) > maxLineWidth;
+            })
+          ) {
+            return null;
           }
+          if (measureLineWidth(words, fontSize) <= maxLineWidth) return [words];
+          var bestSplit = null;
+          var bestImbalance = Infinity;
+          for (var split = 1; split < words.length; split++) {
+            var firstLine = words.slice(0, split);
+            var secondLine = words.slice(split);
+            var firstWidth = measureLineWidth(firstLine, fontSize);
+            var secondWidth = measureLineWidth(secondLine, fontSize);
+            if (firstWidth <= maxLineWidth && secondWidth <= maxLineWidth) {
+              var imbalance = Math.abs(firstWidth - secondWidth);
+              if (imbalance < bestImbalance) {
+                bestSplit = [firstLine, secondLine];
+                bestImbalance = imbalance;
+              }
+            }
+          }
+          return bestSplit;
         }
-        return bestSplit;
-      }
 
-      function fitsInTwoLinesAtSize(words, fontSize) {
-        return splitLinesForGroup(words, fontSize) !== null;
-      }
+        function fitsInTwoLinesAtSize(words, fontSize) {
+          return splitLinesForGroup(words, fontSize) !== null;
+        }
 
-      function planPillLayout(words, fontSize) {
-        var lines = splitLinesForGroup(words, fontSize) || [words];
-        var widestLine = lines.reduce(function (max, lineWords) {
-          return Math.max(max, measureLineWidth(lineWords, fontSize));
-        }, 0);
-        var availablePadding = Math.floor((PILL_MAX_WIDTH - widestLine) / 2);
-        var padX = Math.max(PILL_MIN_PADDING_X, Math.min(PILL_MAX_PADDING_X, availablePadding));
-        var pillWidth = Math.min(PILL_MAX_WIDTH, Math.ceil(widestLine + padX * 2));
-        return { lines: lines, padX: padX, pillWidth: pillWidth };
-      }
+        function planPillLayout(words, fontSize) {
+          var lines = splitLinesForGroup(words, fontSize) || [words];
+          var widestLine = lines.reduce(function (max, lineWords) {
+            return Math.max(max, measureLineWidth(lineWords, fontSize));
+          }, 0);
+          var availablePadding = Math.floor((PILL_MAX_WIDTH - widestLine) / 2);
+          var padX = Math.max(PILL_MIN_PADDING_X, Math.min(PILL_MAX_PADDING_X, availablePadding));
+          var pillWidth = Math.min(PILL_MAX_WIDTH, Math.ceil(widestLine + padX * 2));
+          return { lines: lines, padX: padX, pillWidth: pillWidth };
+        }
 
-      function makeGroups(words) {
-        var groups = [];
-        var current = [];
-        words.forEach(function (word, index) {
-          var testGroup = current.concat([word]);
-          var nextWord = words[index + 1];
-          var wouldExceedMaxWords = testGroup.length > MAX_WORDS_PER_GROUP;
-          var wouldExceedTwoLines = !fitsInTwoLinesAtSize(testGroup, BASE_FONT_SIZE);
-          if (wouldExceedMaxWords || wouldExceedTwoLines) {
-            if (current.length) {
+        function makeGroups(words) {
+          var groups = [];
+          var current = [];
+          words.forEach(function (word, index) {
+            var testGroup = current.concat([word]);
+            var nextWord = words[index + 1];
+            var wouldExceedMaxWords = testGroup.length > MAX_WORDS_PER_GROUP;
+            var wouldExceedTwoLines = !fitsInTwoLinesAtSize(testGroup, BASE_FONT_SIZE);
+            if (wouldExceedMaxWords || wouldExceedTwoLines) {
+              if (current.length) {
+                groups.push({
+                  words: current.slice(),
+                  start: current[0].start,
+                  end: current[current.length - 1].end,
+                });
+              }
+              current = [word];
+              return;
+            }
+            current.push(word);
+            var hasPunctuation = /[,.:!?]$/.test(word.text);
+            var pauseDuration = nextWord ? nextWord.start - word.end : 0;
+            var hasNaturalPause = pauseDuration >= PAUSE_THRESHOLD;
+            var maxWordsReached = current.length >= MAX_WORDS_PER_GROUP;
+            if (maxWordsReached || !nextWord || hasPunctuation || hasNaturalPause) {
               groups.push({
                 words: current.slice(),
                 start: current[0].start,
                 end: current[current.length - 1].end,
               });
+              current = [];
             }
-            current = [word];
-            return;
-          }
-          current.push(word);
-          var hasPunctuation = /[,.:!?]$/.test(word.text);
-          var pauseDuration = nextWord ? nextWord.start - word.end : 0;
-          var hasNaturalPause = pauseDuration >= PAUSE_THRESHOLD;
-          var maxWordsReached = current.length >= MAX_WORDS_PER_GROUP;
-          if (maxWordsReached || !nextWord || hasPunctuation || hasNaturalPause) {
+          });
+          if (current.length)
             groups.push({
               words: current.slice(),
               start: current[0].start,
               end: current[current.length - 1].end,
             });
-            current = [];
+          return groups;
+        }
+
+        function fontSizeForGroup(words) {
+          var size = BASE_FONT_SIZE;
+          // MIN_FONT_SIZE is a hard floor returned unverified below — self-heal
+          // accepts residual overflow at the floor (clipped by the stage)
+          // rather than shrinking below legibility.
+          while (size > MIN_FONT_SIZE && !fitsInTwoLinesAtSize(words, size)) {
+            size -= 2;
           }
-        });
-        if (current.length)
-          groups.push({
-            words: current.slice(),
-            start: current[0].start,
-            end: current[current.length - 1].end,
+          return size;
+        }
+
+        function buildCaptions(groups) {
+          var stage = document.getElementById("caption-stage");
+          groups.forEach(function (group, groupIndex) {
+            var groupEl = document.createElement("div");
+            var pillEl = document.createElement("div");
+            var copyEl = document.createElement("div");
+            var fontSize = fontSizeForGroup(group.words);
+            groupEl.id = "caption-group-" + groupIndex;
+            groupEl.className = "caption-group";
+            pillEl.className = "caption-pill";
+            copyEl.className = "caption-copy";
+            copyEl.style.fontSize = fontSize + "px";
+            var indexedWords = group.words.map(function (word, wordIndex) {
+              return { text: word.text, start: word.start, end: word.end, wordIndex: wordIndex };
+            });
+            var layout = planPillLayout(indexedWords, fontSize);
+            pillEl.style.width = layout.pillWidth + "px";
+            pillEl.style.maxWidth = PILL_MAX_WIDTH + "px";
+            pillEl.style.paddingLeft = layout.padX + "px";
+            pillEl.style.paddingRight = layout.padX + "px";
+            layout.lines.slice(0, 2).forEach(function (lineWords) {
+              var lineEl = document.createElement("div");
+              lineEl.className = "caption-line";
+              lineWords.forEach(function (word) {
+                var wordEl = document.createElement("span");
+                wordEl.id = "caption-word-" + groupIndex + "-" + word.wordIndex;
+                wordEl.className = "caption-word";
+                wordEl.textContent = word.text.toLowerCase();
+                lineEl.appendChild(wordEl);
+              });
+              copyEl.appendChild(lineEl);
+            });
+            pillEl.appendChild(copyEl);
+            groupEl.appendChild(pillEl);
+            stage.appendChild(groupEl);
           });
-        return groups;
-      }
+        }
 
-      function fontSizeForGroup(words) {
-        var size = BASE_FONT_SIZE;
-        while (size > MIN_FONT_SIZE && !fitsInTwoLinesAtSize(words, size)) {
-          size -= 2;
+        function hfTeardown() {
+          document.getElementById("caption-stage").innerHTML = "";
         }
-        return size;
-      }
 
-      function buildCaptions(groups) {
-        var stage = document.getElementById("caption-stage");
-        groups.forEach(function (group, groupIndex) {
-          var groupEl = document.createElement("div");
-          var pillEl = document.createElement("div");
-          var copyEl = document.createElement("div");
-          var fontSize = fontSizeForGroup(group.words);
-          groupEl.id = "caption-group-" + groupIndex;
-          groupEl.className = "caption-group";
-          pillEl.className = "caption-pill";
-          copyEl.className = "caption-copy";
-          copyEl.style.fontSize = fontSize + "px";
-          var indexedWords = group.words.map(function (word, wordIndex) {
-            return { text: word.text, start: word.start, end: word.end, wordIndex: wordIndex };
+        function hfBuild(words, layout, durationS) {
+          DURATION = durationS;
+          BASE_FONT_SIZE = Math.round(72 * layout.fontScale);
+          MIN_FONT_SIZE = Math.round(52 * layout.fontScale);
+          SAFE_ZONE_WIDTH = Math.round(1600 * layout.scaleX);
+          PILL_MAX_WIDTH = SAFE_ZONE_WIDTH;
+          WORD_SPACING = Math.round(16 * layout.fontScale);
+
+          var stage = document.getElementById("caption-stage");
+          var stageHeight = Math.round(220 * layout.fontScale);
+          stage.style.width = SAFE_ZONE_WIDTH + "px";
+          stage.style.height = stageHeight + "px";
+          stage.style.bottom = Math.round(90 * layout.scaleY) + "px";
+
+          var rootEl = document.getElementById(HF_ROOT_ID);
+          var accent = getComputedStyle(rootEl).getPropertyValue("--hf-caption-accent").trim();
+          hfColorActive = accent || COLOR_ACTIVE;
+
+          var WORDS = normalizeWords(words);
+          var GROUPS = makeGroups(WORDS);
+          buildCaptions(GROUPS);
+          GROUPS.forEach(function (_, i) {
+            var el = document.getElementById("caption-group-" + i);
+            el.style.width = SAFE_ZONE_WIDTH + "px";
+            el.style.height = stageHeight + "px";
           });
-          var layout = planPillLayout(indexedWords, fontSize);
-          pillEl.style.width = layout.pillWidth + "px";
-          pillEl.style.paddingLeft = layout.padX + "px";
-          pillEl.style.paddingRight = layout.padX + "px";
-          layout.lines.slice(0, 2).forEach(function (lineWords) {
-            var lineEl = document.createElement("div");
-            lineEl.className = "caption-line";
-            lineWords.forEach(function (word) {
-              var wordEl = document.createElement("span");
-              wordEl.id = "caption-word-" + groupIndex + "-" + word.wordIndex;
-              wordEl.className = "caption-word";
-              wordEl.textContent = word.text.toLowerCase();
-              lineEl.appendChild(wordEl);
+
+          var tl = gsap.timeline({ paused: true });
+
+          GROUPS.forEach(function (group, groupIndex) {
+            var groupEl = document.getElementById("caption-group-" + groupIndex);
+            var nextGroup = GROUPS[groupIndex + 1];
+            var isLastGroup = groupIndex === GROUPS.length - 1;
+            var effectiveEnd = isLastGroup
+              ? DURATION
+              : Math.min(nextGroup.start, group.end + GROUP_END_BUFFER);
+            var visibleStart = Math.max(0, group.start);
+            var visibleEnd = Math.max(visibleStart + 0.01, effectiveEnd);
+
+            tl.set(groupEl, { opacity: 1 }, visibleStart);
+            tl.set(groupEl, { opacity: 0 }, visibleEnd);
+
+            group.words.forEach(function (word, wordIndex) {
+              var wordEl = document.getElementById("caption-word-" + groupIndex + "-" + wordIndex);
+              var isFirstWord = wordIndex === 0;
+              var wordStart = Math.max(visibleStart, word.start - WORD_FADE_LEAD);
+              tl.set(wordEl, { color: isFirstWord ? hfColorActive : COLOR_INACTIVE }, visibleStart);
+              if (isFirstWord) return;
+              tl.to(
+                wordEl,
+                { color: hfColorActive, duration: COLOR_FADE_DURATION, ease: "none" },
+                wordStart,
+              );
             });
-            copyEl.appendChild(lineEl);
           });
-          pillEl.appendChild(copyEl);
-          groupEl.appendChild(pillEl);
-          stage.appendChild(groupEl);
-        });
-      }
 
-      var WORDS = normalizeWords(TRANSCRIPT);
-      var GROUPS = makeGroups(WORDS);
-      buildCaptions(GROUPS);
-
-      window.__timelines = window.__timelines || {};
-      var tl = gsap.timeline({ paused: true });
-
-      GROUPS.forEach(function (group, groupIndex) {
-        var groupEl = document.getElementById("caption-group-" + groupIndex);
-        var nextGroup = GROUPS[groupIndex + 1];
-        var isLastGroup = groupIndex === GROUPS.length - 1;
-        var effectiveEnd = isLastGroup
-          ? DURATION
-          : Math.min(nextGroup.start, group.end + GROUP_END_BUFFER);
-        var visibleStart = Math.max(0, group.start);
-        var visibleEnd = Math.max(visibleStart + 0.01, effectiveEnd);
-
-        tl.set(groupEl, { opacity: 1 }, visibleStart);
-        tl.set(groupEl, { opacity: 0 }, visibleEnd);
-
-        group.words.forEach(function (word, wordIndex) {
-          var wordEl = document.getElementById("caption-word-" + groupIndex + "-" + wordIndex);
-          var isFirstWord = wordIndex === 0;
-          var wordStart = Math.max(visibleStart, word.start - WORD_FADE_LEAD);
-          tl.set(wordEl, { color: isFirstWord ? COLOR_ACTIVE : COLOR_INACTIVE }, visibleStart);
-          if (isFirstWord) return;
-          tl.to(
-            wordEl,
-            { color: COLOR_ACTIVE, duration: COLOR_FADE_DURATION, ease: "none" },
-            wordStart,
-          );
-        });
-      });
+          return tl;
+        }
+
+        var hfCurrentTimeline = null;
 
-      window.__timelines["caption-pill-karaoke"] = tl;
+        function hfAttach(data) {
+          var v = hfValidate(data);
+          if (!v.ok) {
+            hfRunGate([], 0, v.reason);
+            return;
+          }
+          if (hfCurrentTimeline) {
+            hfCurrentTimeline.kill();
+            hfCurrentTimeline = null;
+          }
+          hfTeardown();
+          var layout = hfApplyStageConfig(data, v.durationS);
+          var tl = hfBuild(v.words, layout, v.durationS);
+          tl.set({}, {}, v.durationS); // pin timeline length to the data-derived duration
+          // GSAP quirk (confirmed 3.14.2): a fresh timeline already reports position 0,
+          // so seek(0) is treated as a no-op and skips rendering .set() calls scheduled
+          // at t=0 — the first frame would show pre-timeline CSS defaults (usually
+          // hidden). render(time, suppressEvents, force) with force=true bypasses that.
+          tl.render(0, true, true);
+          hfCurrentTimeline = tl;
+          window.__timelines = window.__timelines || {};
+          window.__timelines[HF_COMPOSITION_ID] = tl;
+          hfRunGate(v.words, v.durationS, null);
+        }
+        window.__HF_CAPTION_ATTACH__ = hfAttach;
+
+        (function hfBoot() {
+          function start(data) {
+            var ready =
+              document.fonts && document.fonts.ready ? document.fonts.ready : Promise.resolve();
+            ready.then(function () {
+              // A manual window.__HF_CAPTION_ATTACH__ call that lands while the
+              // sibling fetch / fonts.ready are still pending must win — never
+              // clobber it with the late-arriving boot payload.
+              if (hfCurrentTimeline) return;
+              hfAttach(data);
+            });
+          }
+          if (window.__HF_CAPTION__) {
+            start(window.__HF_CAPTION__);
+            return;
+          }
+          fetch("./caption-data.json")
+            .then(function (r) {
+              return r.ok ? r.json() : null;
+            })
+            .catch(function () {
+              return null;
+            })
+            .then(function (json) {
+              start(json || HF_DEMO_DATA);
+            });
+        })();
+      })();
     </script>
   </body>
 </html>
diff --git a/registry/components/caption-weight-shift/caption-weight-shift.html b/registry/components/caption-weight-shift/caption-weight-shift.html
index a6f37fe0b7..b42c4e59ae 100644
--- a/registry/components/caption-weight-shift/caption-weight-shift.html
+++ b/registry/components/caption-weight-shift/caption-weight-shift.html
@@ -90,7 +90,7 @@
         max-width: 1400px;
         line-height: 1.1;
         white-space: nowrap;
-        color: #ffffff;
+        color: var(--hf-caption-primary, #ffffff);
         font-family: "Montserrat", Arial, sans-serif;
         font-weight: 300;
         font-size: 72px;
@@ -117,281 +117,568 @@
     </div>
 
     <script>
-      var DURATION = 8;
-      var SAFE_ZONE_WIDTH = 1400;
-      var MAX_LINE_WIDTH = SAFE_ZONE_WIDTH - 40;
-      var CAPTION_FONT_SIZE = 72;
-      var MAX_WORDS_PER_GROUP = 4;
-      var WORD_SPACING = 12;
-      var PAUSE_THRESHOLD = 0.1;
-      var ENTRY_DURATION = 100 / 1000;
-      var WEIGHT_TRANSITION = 100 / 1000;
-      var FONT_WIDTH_SAFETY = 1.14;
-      var FONT_WEIGHT_LIGHT = 300;
-      var FONT_WEIGHT_BOLD = 700;
-
-      var TRANSCRIPT = [
-        { text: "Every", start: 0.0, end: 0.3 },
-        { text: "great", start: 0.3, end: 0.55 },
-        { text: "video", start: 0.55, end: 0.85 },
-        { text: "starts", start: 0.85, end: 1.1 },
-        { text: "with", start: 1.1, end: 1.25 },
-        { text: "a", start: 1.25, end: 1.35 },
-        { text: "single", start: 1.35, end: 1.65 },
-        { text: "frame.", start: 1.65, end: 2.0 },
-        { text: "HyperFrames", start: 2.1, end: 2.65 },
-        { text: "lets", start: 2.65, end: 2.85 },
-        { text: "you", start: 2.85, end: 2.95 },
-        { text: "write", start: 2.95, end: 3.15 },
-        { text: "HTML", start: 3.15, end: 3.55 },
-        { text: "and", start: 3.55, end: 3.65 },
-        { text: "render", start: 3.65, end: 3.95 },
-        { text: "professional", start: 3.95, end: 4.45 },
-        { text: "video.", start: 4.45, end: 4.8 },
-        { text: "No", start: 4.9, end: 5.05 },
-        { text: "timeline.", start: 5.05, end: 5.45 },
-        { text: "No", start: 5.5, end: 5.65 },
-        { text: "drag", start: 5.65, end: 5.85 },
-        { text: "and", start: 5.85, end: 5.95 },
-        { text: "drop.", start: 5.95, end: 6.25 },
-        { text: "Just", start: 6.35, end: 6.55 },
-        { text: "code", start: 6.55, end: 6.8 },
-        { text: "that", start: 6.8, end: 6.95 },
-        { text: "becomes", start: 6.95, end: 7.3 },
-        { text: "cinema.", start: 7.3, end: 7.7 },
-      ];
-
-      function normalizeWords(rawWords) {
-        return rawWords
-          .map(function (item) {
-            return {
-              text: String(item.word || item.text || "").trim(),
-              start: Math.max(0, Number(item.start) || 0),
-              end: Math.min(DURATION, Math.max(Number(item.start) || 0, Number(item.end) || 0)),
-            };
-          })
-          .filter(function (word) {
-            return word.text.length > 0;
+      // IIFE: keep every template's runtime private to itself so two caption
+      // components pasted into one composition document can't clobber each
+      // other's hfAttach/hfBuild via shared script-scope names (boot is async,
+      // so collisions surface AFTER all scripts have executed).
+      (function () {
+        var HF_COMPOSITION_ID = "caption-weight-shift";
+        var HF_ROOT_ID = "weight-shift";
+        var HF_GROUP_SELECTOR = ".caption-group";
+
+        var HF_DEMO_DATA = {
+          version: 1,
+          segments: [
+            {
+              start: 0,
+              text: "Every great video starts with a single frame. HyperFrames lets you write HTML and render professional video. No timeline. No drag and drop. Just code that becomes cinema.",
+              words: [
+                { text: "Every", start: 0.0, end: 0.3 },
+                { text: "great", start: 0.3, end: 0.55 },
+                { text: "video", start: 0.55, end: 0.85 },
+                { text: "starts", start: 0.85, end: 1.1 },
+                { text: "with", start: 1.1, end: 1.25 },
+                { text: "a", start: 1.25, end: 1.35 },
+                { text: "single", start: 1.35, end: 1.65 },
+                { text: "frame.", start: 1.65, end: 2.0 },
+                { text: "HyperFrames", start: 2.1, end: 2.65 },
+                { text: "lets", start: 2.65, end: 2.85 },
+                { text: "you", start: 2.85, end: 2.95 },
+                { text: "write", start: 2.95, end: 3.15 },
+                { text: "HTML", start: 3.15, end: 3.55 },
+                { text: "and", start: 3.55, end: 3.65 },
+                { text: "render", start: 3.65, end: 3.95 },
+                { text: "professional", start: 3.95, end: 4.45 },
+                { text: "video.", start: 4.45, end: 4.8 },
+                { text: "No", start: 4.9, end: 5.05 },
+                { text: "timeline.", start: 5.05, end: 5.45 },
+                { text: "No", start: 5.5, end: 5.65 },
+                { text: "drag", start: 5.65, end: 5.85 },
+                { text: "and", start: 5.85, end: 5.95 },
+                { text: "drop.", start: 5.95, end: 6.25 },
+                { text: "Just", start: 6.35, end: 6.55 },
+                { text: "code", start: 6.55, end: 6.8 },
+                { text: "that", start: 6.8, end: 6.95 },
+                { text: "becomes", start: 6.95, end: 7.3 },
+                { text: "cinema.", start: 7.3, end: 7.7 },
+              ],
+            },
+          ],
+        };
+
+        /* ── HyperFrames caption-data runtime (shared across caption templates) ── */
+        var HF_CONTRACT_VERSION = 1;
+        var HF_DEFAULT_RESOLUTION = { width: 1920, height: 1080 };
+
+        function hfFlattenSegments(segments) {
+          var out = [];
+          (segments || []).forEach(function (seg) {
+            ((seg && seg.words) || []).forEach(function (w) {
+              var start = Math.max(0, Number(w.start) || 0);
+              out.push({
+                text: String(w.word || w.text || "").trim(),
+                start: start,
+                end: Math.max(start, Number(w.end) || 0),
+              });
+            });
           });
-      }
+          out.sort(function (a, b) {
+            return a.start - b.start;
+          });
+          return out.filter(function (w) {
+            return w.text.length > 0;
+          });
+        }
 
-      var _fitCanvas = document.createElement("canvas");
-      var _fitCtx = _fitCanvas.getContext("2d");
-      function fitFontSize(text, baseFontSize, fontWeight, fontFamily, maxWidth) {
-        var size = baseFontSize;
-        var minSize = Math.floor(baseFontSize * 0.45);
-        while (size > minSize) {
-          _fitCtx.font = fontWeight + " " + size + "px " + fontFamily;
-          if (_fitCtx.measureText(text).width <= maxWidth) return size;
-          size -= 2;
+        function hfDeriveDuration(words) {
+          var end = 0;
+          words.forEach(function (w) {
+            if (w.end > end) end = w.end;
+          });
+          return end;
         }
-        return minSize;
-      }
 
-      var measureCanvas = document.createElement("canvas");
-      var measureContext = measureCanvas.getContext("2d");
-      measureContext.font = "700 " + CAPTION_FONT_SIZE + "px Montserrat";
+        function hfValidate(data) {
+          if (!data || typeof data !== "object") return { ok: false, reason: "not-an-object" };
+          if (data.version != null) {
+            // Number("v2") is NaN and NaN > x is always false — an explicit
+            // finite check keeps malformed versions from slipping past the gate.
+            var hfVersion = Number(data.version);
+            if (!Number.isFinite(hfVersion) || Math.floor(hfVersion) > HF_CONTRACT_VERSION) {
+              return { ok: false, reason: "unsupported-version" };
+            }
+          }
+          if (!Array.isArray(data.segments) || data.segments.length === 0) {
+            return { ok: false, reason: "no-segments" };
+          }
+          if (data.displayMode != null && data.displayMode !== "full") {
+            return { ok: false, reason: "unsupported-displayMode" };
+          }
+          var words = hfFlattenSegments(data.segments);
+          if (words.length === 0) return { ok: false, reason: "no-words" };
+          return { ok: true, words: words, durationS: hfDeriveDuration(words) };
+        }
 
-      function measureWord(word) {
-        return measureContext.measureText(word.text.toLowerCase()).width * FONT_WIDTH_SAFETY;
-      }
+        function hfApplyStageConfig(data, durationS) {
+          var res = (data && data.resolution) || HF_DEFAULT_RESOLUTION;
+          // Mirror the published validator's <=8192 bound defensively — the
+          // validator is an optional pre-flight, and an unbounded stage size
+          // would OOM render workers.
+          var W = Math.min(
+            8192,
+            Math.max(1, Math.round(Number(res.width) || HF_DEFAULT_RESOLUTION.width)),
+          );
+          var H = Math.min(
+            8192,
+            Math.max(1, Math.round(Number(res.height) || HF_DEFAULT_RESOLUTION.height)),
+          );
+          var root = document.getElementById(HF_ROOT_ID);
+          [document.documentElement, document.body, root].forEach(function (el) {
+            el.style.width = W + "px";
+            el.style.height = H + "px";
+          });
+          root.setAttribute("data-width", String(W));
+          root.setAttribute("data-height", String(H));
+          root.setAttribute("data-duration", String(durationS));
+          var brand = (data && data.brand) || {};
+          if (typeof brand.primaryColor === "string" && brand.primaryColor) {
+            root.style.setProperty("--hf-caption-primary", brand.primaryColor);
+          } else {
+            root.style.removeProperty("--hf-caption-primary");
+          }
+          if (typeof brand.accentColor === "string" && brand.accentColor) {
+            root.style.setProperty("--hf-caption-accent", brand.accentColor);
+          } else {
+            root.style.removeProperty("--hf-caption-accent");
+          }
+          return {
+            W: W,
+            H: H,
+            scaleX: W / 1920,
+            scaleY: H / 1080,
+            fontScale: Math.min(W, H) / 1080,
+          };
+        }
 
-      function measureLineWidth(words) {
-        return words.reduce(function (total, word, index) {
-          return total + measureWord(word) + (index ? WORD_SPACING : 0);
-        }, 0);
-      }
+        function hfPublishStatus(status) {
+          window.__HF_CAPTION_STATUS = status;
+          document
+            .getElementById(HF_ROOT_ID)
+            .setAttribute("data-caption-status", status.ok ? "ok" : "failed");
+        }
 
-      function fitsInTwoLines(words) {
-        return measureLineWidth(words) <= MAX_LINE_WIDTH * 1.8;
-      }
+        function hfRunGate(words, durationS, failReason) {
+          if (failReason) {
+            hfPublishStatus({
+              ok: false,
+              present: false,
+              contained: false,
+              reason: failReason,
+              version: HF_CONTRACT_VERSION,
+              durationS: durationS || 0,
+            });
+            return;
+          }
+          var root = document.getElementById(HF_ROOT_ID);
+          var rootRect = root.getBoundingClientRect();
+          var groups = root.querySelectorAll(HF_GROUP_SELECTOR);
+          var present = false;
+          var contained = true;
+          var tokens = [];
+          words.forEach(function (w) {
+            var t = w.text.toLowerCase().replace(/[^a-z0-9]/g, "");
+            if (t) tokens.push(t);
+          });
+          groups.forEach(function (el) {
+            var prevOpacity = el.style.opacity;
+            var prevVisibility = el.style.visibility;
+            el.style.opacity = "1";
+            el.style.visibility = "visible";
+            var r = el.getBoundingClientRect();
+            if (r.width > 0 && r.height > 0) {
+              var text = (el.textContent || "").toLowerCase();
+              for (var i = 0; i < tokens.length; i++) {
+                if (text.indexOf(tokens[i]) !== -1) {
+                  present = true;
+                  break;
+                }
+              }
+              if (
+                r.left < rootRect.left - 1 ||
+                r.right > rootRect.right + 1 ||
+                r.top < rootRect.top - 1 ||
+                r.bottom > rootRect.bottom + 1
+              ) {
+                contained = false;
+              }
+            }
+            el.style.opacity = prevOpacity;
+            el.style.visibility = prevVisibility;
+          });
+          hfPublishStatus({
+            ok: present && contained,
+            present: present,
+            contained: contained,
+            version: HF_CONTRACT_VERSION,
+            durationS: durationS,
+          });
+        }
 
-      function splitLines(words) {
-        if (words.length < 2) {
-          return [{ words: words, startIndex: 0 }];
+        var SAFE_ZONE_WIDTH, MAX_LINE_WIDTH, CAPTION_FONT_SIZE, DURATION;
+        var MAX_WORDS_PER_GROUP = 4;
+        var WORD_SPACING_DESIGN = 12;
+        var WORD_SPACING;
+        var PAUSE_THRESHOLD = 0.1;
+        var ENTRY_DURATION = 100 / 1000;
+        var WEIGHT_TRANSITION = 100 / 1000;
+        var FONT_WIDTH_SAFETY = 1.14;
+        var FONT_WEIGHT_LIGHT = 300;
+        var FONT_WEIGHT_BOLD = 700;
+
+        function normalizeWords(rawWords) {
+          return rawWords
+            .map(function (item) {
+              return {
+                text: String(item.word || item.text || "").trim(),
+                start: Math.max(0, Number(item.start) || 0),
+                end: Math.min(DURATION, Math.max(Number(item.start) || 0, Number(item.end) || 0)),
+              };
+            })
+            .filter(function (word) {
+              return word.text.length > 0;
+            });
         }
-        var bestSplit = Math.ceil(words.length / 2);
-        var bestDiff = Infinity;
-        for (var s = 1; s < words.length; s++) {
-          var w1 = measureLineWidth(words.slice(0, s));
-          var w2 = measureLineWidth(words.slice(s));
-          if (w1 <= MAX_LINE_WIDTH && w2 <= MAX_LINE_WIDTH) {
-            var diff = Math.abs(w1 - w2);
-            if (diff < bestDiff) {
-              bestDiff = diff;
-              bestSplit = s;
-            }
+
+        var _fitCanvas = document.createElement("canvas");
+        var _fitCtx = _fitCanvas.getContext("2d");
+        function fitFontSize(text, baseFontSize, fontWeight, fontFamily, maxWidth) {
+          var size = baseFontSize;
+          var minSize = Math.floor(baseFontSize * 0.45);
+          // minSize is a hard floor returned unverified below — self-heal
+          // accepts residual overflow at the floor (clipped by the stage)
+          // rather than shrinking below legibility.
+          while (size > minSize) {
+            _fitCtx.font = fontWeight + " " + size + "px " + fontFamily;
+            if (_fitCtx.measureText(text).width <= maxWidth) return size;
+            size -= 2;
           }
+          return minSize;
         }
-        var result = [];
-        var line1 = words.slice(0, bestSplit);
-        var line2 = words.slice(bestSplit);
-        if (line1.length) result.push({ words: line1, startIndex: 0 });
-        if (line2.length) result.push({ words: line2, startIndex: line1.length });
-        return result;
-      }
 
-      function avoidSingleWordGroups(groups) {
-        var out = [];
-        groups.forEach(function (group) {
-          if (
-            group.words.length === 1 &&
-            out.length > 0 &&
-            out[out.length - 1].words.length < MAX_WORDS_PER_GROUP
-          ) {
-            out[out.length - 1] = makeGroup(out[out.length - 1].words.concat(group.words));
-          } else {
-            out.push(group);
+        var measureCanvas = document.createElement("canvas");
+        var measureContext = measureCanvas.getContext("2d");
+
+        function measureWord(word) {
+          return measureContext.measureText(word.text.toLowerCase()).width * FONT_WIDTH_SAFETY;
+        }
+
+        function measureLineWidth(words) {
+          return words.reduce(function (total, word, index) {
+            return total + measureWord(word) + (index ? WORD_SPACING : 0);
+          }, 0);
+        }
+
+        function fitsInTwoLines(words) {
+          return measureLineWidth(words) <= MAX_LINE_WIDTH * 1.8;
+        }
+
+        function splitLines(words) {
+          if (words.length < 2) {
+            return [{ words: words, startIndex: 0 }];
           }
-        });
-
-        for (var i = 0; i < out.length; i++) {
-          if (out[i].words.length !== 1) continue;
-          if (i + 1 < out.length && out[i + 1].words.length < MAX_WORDS_PER_GROUP) {
-            out[i] = makeGroup(out[i].words.concat(out[i + 1].words));
-            out.splice(i + 1, 1);
-          } else if (i > 0 && out[i - 1].words.length < MAX_WORDS_PER_GROUP) {
-            out[i - 1] = makeGroup(out[i - 1].words.concat(out[i].words));
-            out.splice(i, 1);
-            i--;
+          var bestSplit = Math.ceil(words.length / 2);
+          var bestDiff = Infinity;
+          for (var s = 1; s < words.length; s++) {
+            var w1 = measureLineWidth(words.slice(0, s));
+            var w2 = measureLineWidth(words.slice(s));
+            if (w1 <= MAX_LINE_WIDTH && w2 <= MAX_LINE_WIDTH) {
+              var diff = Math.abs(w1 - w2);
+              if (diff < bestDiff) {
+                bestDiff = diff;
+                bestSplit = s;
+              }
+            }
           }
+          var result = [];
+          var line1 = words.slice(0, bestSplit);
+          var line2 = words.slice(bestSplit);
+          if (line1.length) result.push({ words: line1, startIndex: 0 });
+          if (line2.length) result.push({ words: line2, startIndex: line1.length });
+          return result;
         }
 
-        return out;
-      }
+        function avoidSingleWordGroups(groups) {
+          var out = [];
+          groups.forEach(function (group) {
+            if (
+              group.words.length === 1 &&
+              out.length > 0 &&
+              out[out.length - 1].words.length < MAX_WORDS_PER_GROUP &&
+              // makeGroups guards every addition with fitsInTwoLines; this
+              // second-pass merge must too, or it can produce a group that
+              // splitLines cannot fit within MAX_LINE_WIDTH.
+              fitsInTwoLines(out[out.length - 1].words.concat(group.words))
+            ) {
+              out[out.length - 1] = makeGroup(out[out.length - 1].words.concat(group.words));
+            } else {
+              out.push(group);
+            }
+          });
 
-      function makeGroups(words) {
-        var groups = [];
-        var current = [];
-        words.forEach(function (word, index) {
-          var nextWord = words[index + 1];
-          var testGroup = current.concat([word]);
-          if (testGroup.length > MAX_WORDS_PER_GROUP || !fitsInTwoLines(testGroup)) {
-            if (current.length) groups.push(makeGroup(current));
-            current = [word];
-            return;
-          }
-          current.push(word);
-          var punctuation = /[,.:!?]$/.test(word.text);
-          var pause = nextWord ? nextWord.start - word.end : 0;
-          if (
-            !nextWord ||
-            punctuation ||
-            pause >= PAUSE_THRESHOLD ||
-            current.length >= MAX_WORDS_PER_GROUP
-          ) {
-            groups.push(makeGroup(current));
-            current = [];
+          for (var i = 0; i < out.length; i++) {
+            if (out[i].words.length !== 1) continue;
+            if (
+              i + 1 < out.length &&
+              out[i + 1].words.length < MAX_WORDS_PER_GROUP &&
+              fitsInTwoLines(out[i].words.concat(out[i + 1].words))
+            ) {
+              out[i] = makeGroup(out[i].words.concat(out[i + 1].words));
+              out.splice(i + 1, 1);
+            } else if (
+              i > 0 &&
+              out[i - 1].words.length < MAX_WORDS_PER_GROUP &&
+              fitsInTwoLines(out[i - 1].words.concat(out[i].words))
+            ) {
+              out[i - 1] = makeGroup(out[i - 1].words.concat(out[i].words));
+              out.splice(i, 1);
+              i--;
+            }
           }
-        });
-        if (current.length) groups.push(makeGroup(current));
-        return avoidSingleWordGroups(groups);
-      }
 
-      function makeGroup(words) {
-        return {
-          words: words.slice(),
-          lines: splitLines(words),
-          start: words[0].start,
-          end: words[words.length - 1].end,
-        };
-      }
+          return out;
+        }
 
-      function buildCaptions(groups) {
-        var stage = document.getElementById("caption-stage");
-        groups.forEach(function (group, groupIndex) {
-          var groupText = group.words
-            .map(function (w) {
-              return w.text.toLowerCase();
-            })
-            .join(" ");
-          var computedSize = fitFontSize(
-            groupText,
-            CAPTION_FONT_SIZE,
-            "700",
-            "Montserrat",
-            MAX_LINE_WIDTH,
-          );
-          var groupEl = document.createElement("div");
-          var copyEl = document.createElement("div");
-          groupEl.id = "caption-group-" + groupIndex;
-          groupEl.className = "caption-group";
-          copyEl.className = "caption-copy";
-          group.lines.forEach(function (line, lineIndex) {
-            var lineEl = document.createElement("div");
-            lineEl.className = "caption-line";
-            lineEl.id = "caption-group-" + groupIndex + "-line-" + lineIndex;
-            lineEl.style.fontWeight = lineIndex === 0 ? FONT_WEIGHT_BOLD : FONT_WEIGHT_LIGHT;
-            lineEl.style.fontSize = computedSize + "px";
-            line.words.forEach(function (word, wordIndex) {
-              var wordEl = document.createElement("span");
-              wordEl.textContent = word.text.toLowerCase();
-              wordEl.style.display = "inline-block";
-              lineEl.appendChild(wordEl);
+        function makeGroups(words) {
+          var groups = [];
+          var current = [];
+          words.forEach(function (word, index) {
+            var nextWord = words[index + 1];
+            var testGroup = current.concat([word]);
+            if (testGroup.length > MAX_WORDS_PER_GROUP || !fitsInTwoLines(testGroup)) {
+              if (current.length) groups.push(makeGroup(current));
+              current = [word];
+              return;
+            }
+            current.push(word);
+            var punctuation = /[,.:!?]$/.test(word.text);
+            var pause = nextWord ? nextWord.start - word.end : 0;
+            if (
+              !nextWord ||
+              punctuation ||
+              pause >= PAUSE_THRESHOLD ||
+              current.length >= MAX_WORDS_PER_GROUP
+            ) {
+              groups.push(makeGroup(current));
+              current = [];
+            }
+          });
+          if (current.length) groups.push(makeGroup(current));
+          return avoidSingleWordGroups(groups);
+        }
+
+        function makeGroup(words) {
+          return {
+            words: words.slice(),
+            lines: splitLines(words),
+            start: words[0].start,
+            end: words[words.length - 1].end,
+          };
+        }
+
+        function buildCaptions(groups) {
+          var stage = document.getElementById("caption-stage");
+          groups.forEach(function (group, groupIndex) {
+            // Fit the WIDEST split line, not the joined group text: the group
+            // renders across up to two lines, so sizing against the joined
+            // string shrank two-line groups that already fit at full size.
+            var widestLineText = "";
+            var widestLineWidth = -1;
+            group.lines.forEach(function (line) {
+              var lineWidth = measureLineWidth(line.words);
+              if (lineWidth > widestLineWidth) {
+                widestLineWidth = lineWidth;
+                widestLineText = line.words
+                  .map(function (w) {
+                    return w.text.toLowerCase();
+                  })
+                  .join(" ");
+              }
+            });
+            var computedSize = fitFontSize(
+              widestLineText,
+              CAPTION_FONT_SIZE,
+              "700",
+              "Montserrat",
+              MAX_LINE_WIDTH,
+            );
+            var groupEl = document.createElement("div");
+            var copyEl = document.createElement("div");
+            groupEl.id = "caption-group-" + groupIndex;
+            groupEl.className = "caption-group";
+            copyEl.className = "caption-copy";
+            group.lines.forEach(function (line, lineIndex) {
+              var lineEl = document.createElement("div");
+              lineEl.className = "caption-line";
+              lineEl.id = "caption-group-" + groupIndex + "-line-" + lineIndex;
+              lineEl.style.fontWeight = lineIndex === 0 ? FONT_WEIGHT_BOLD : FONT_WEIGHT_LIGHT;
+              lineEl.style.fontSize = computedSize + "px";
+              lineEl.style.maxWidth = SAFE_ZONE_WIDTH + "px";
+              line.words.forEach(function (word, wordIndex) {
+                var wordEl = document.createElement("span");
+                wordEl.textContent = word.text.toLowerCase();
+                wordEl.style.display = "inline-block";
+                lineEl.appendChild(wordEl);
+              });
+              copyEl.appendChild(lineEl);
             });
-            copyEl.appendChild(lineEl);
+            groupEl.appendChild(copyEl);
+            stage.appendChild(groupEl);
           });
-          groupEl.appendChild(copyEl);
-          stage.appendChild(groupEl);
-        });
-      }
+        }
 
-      var WORDS = normalizeWords(TRANSCRIPT);
-      var GROUPS = makeGroups(WORDS);
-      buildCaptions(GROUPS);
-
-      window.__timelines = window.__timelines || {};
-      var tl = gsap.timeline({ paused: true });
-
-      var visibleStarts = GROUPS.map(function (group, groupIndex) {
-        var prev = GROUPS[groupIndex - 1];
-        var availableGap = prev ? Math.max(0, group.start - prev.end) : ENTRY_DURATION;
-        var entryLead = Math.min(ENTRY_DURATION, availableGap);
-        return Math.max(0, group.start - entryLead);
-      });
-
-      var allGroupEls = GROUPS.map(function (_, i) {
-        return document.getElementById("caption-group-" + i);
-      });
-
-      GROUPS.forEach(function (group, groupIndex) {
-        var groupEl = allGroupEls[groupIndex];
-        var visibleStart = visibleStarts[groupIndex];
-        var visibleEnd = groupIndex < GROUPS.length - 1 ? visibleStarts[groupIndex + 1] : DURATION;
-
-        allGroupEls.forEach(function (otherEl, otherIndex) {
-          if (otherIndex !== groupIndex) tl.set(otherEl, { opacity: 0 }, visibleStart);
-        });
-
-        tl.set(groupEl, { opacity: 0, scale: 0.85 }, visibleStart);
-        tl.to(
-          groupEl,
-          { opacity: 1, scale: 1, duration: ENTRY_DURATION, ease: "power3.out", force3D: true },
-          visibleStart,
-        );
-
-        if (group.lines.length === 2) {
-          var line1El = document.getElementById("caption-group-" + groupIndex + "-line-0");
-          var line2El = document.getElementById("caption-group-" + groupIndex + "-line-1");
-          var line2FirstWord = group.lines[1].words[0];
-          var switchTime = line2FirstWord.start;
-
-          tl.to(
-            line1El,
-            { fontWeight: FONT_WEIGHT_LIGHT, duration: WEIGHT_TRANSITION, ease: "power2.out" },
-            switchTime,
-          );
-          tl.to(
-            line2El,
-            { fontWeight: FONT_WEIGHT_BOLD, duration: WEIGHT_TRANSITION, ease: "power2.out" },
-            switchTime,
-          );
+        function hfTeardown() {
+          document.getElementById("caption-stage").innerHTML = "";
         }
 
-        tl.set(groupEl, { opacity: 0 }, visibleEnd);
-      });
+        function hfBuild(words, layout, durationS) {
+          DURATION = durationS;
+          CAPTION_FONT_SIZE = Math.round(72 * layout.fontScale);
+          SAFE_ZONE_WIDTH = Math.round(1400 * layout.scaleX);
+          MAX_LINE_WIDTH = SAFE_ZONE_WIDTH - Math.round(40 * layout.scaleX);
+          WORD_SPACING = Math.round(WORD_SPACING_DESIGN * layout.fontScale);
+
+          var stage = document.getElementById("caption-stage");
+          var stageHeight = Math.round(278 * layout.fontScale);
+          stage.style.width = SAFE_ZONE_WIDTH + "px";
+          stage.style.height = stageHeight + "px";
+          stage.style.bottom = Math.round(100 * layout.scaleY) + "px";
+
+          measureContext.font = "700 " + CAPTION_FONT_SIZE + "px Montserrat";
+
+          var WORDS = normalizeWords(words);
+          var GROUPS = makeGroups(WORDS);
+          buildCaptions(GROUPS);
+          // set per-group sizing to match the runtime stage
+          GROUPS.forEach(function (_, i) {
+            var el = document.getElementById("caption-group-" + i);
+            el.style.width = SAFE_ZONE_WIDTH + "px";
+            el.style.height = stageHeight + "px";
+          });
+
+          var tl = gsap.timeline({ paused: true });
+
+          var visibleStarts = GROUPS.map(function (group, groupIndex) {
+            var prev = GROUPS[groupIndex - 1];
+            var availableGap = prev ? Math.max(0, group.start - prev.end) : ENTRY_DURATION;
+            var entryLead = Math.min(ENTRY_DURATION, availableGap);
+            return Math.max(0, group.start - entryLead);
+          });
+
+          var allGroupEls = GROUPS.map(function (_, i) {
+            return document.getElementById("caption-group-" + i);
+          });
+
+          GROUPS.forEach(function (group, groupIndex) {
+            var groupEl = allGroupEls[groupIndex];
+            var visibleStart = visibleStarts[groupIndex];
+            var visibleEnd =
+              groupIndex < GROUPS.length - 1 ? visibleStarts[groupIndex + 1] : DURATION;
+
+            // Each group already owns its full opacity lifecycle (set 0 at its
+            // own visibleStart, animated to 1, then set back to 0 at its own
+            // visibleEnd below), and groups occupy non-overlapping windows, so
+            // explicitly hiding every OTHER group here was redundant and made
+            // timeline construction O(groups^2) — this collapsed under dense
+            // stress transcripts (many short groups). Removed; behavior is
+            // unchanged (verified against templates.test.ts).
+
+            tl.set(groupEl, { opacity: 0, scale: 0.85 }, visibleStart);
+            tl.to(
+              groupEl,
+              { opacity: 1, scale: 1, duration: ENTRY_DURATION, ease: "power3.out", force3D: true },
+              visibleStart,
+            );
+
+            if (group.lines.length === 2) {
+              var line1El = document.getElementById("caption-group-" + groupIndex + "-line-0");
+              var line2El = document.getElementById("caption-group-" + groupIndex + "-line-1");
+              var line2FirstWord = group.lines[1].words[0];
+              var switchTime = line2FirstWord.start;
+
+              tl.to(
+                line1El,
+                { fontWeight: FONT_WEIGHT_LIGHT, duration: WEIGHT_TRANSITION, ease: "power2.out" },
+                switchTime,
+              );
+              tl.to(
+                line2El,
+                { fontWeight: FONT_WEIGHT_BOLD, duration: WEIGHT_TRANSITION, ease: "power2.out" },
+                switchTime,
+              );
+            }
+
+            tl.set(groupEl, { opacity: 0 }, visibleEnd);
+          });
+
+          return tl;
+        }
 
-      window.__timelines["caption-weight-shift"] = tl;
+        var hfCurrentTimeline = null;
+
+        function hfAttach(data) {
+          var v = hfValidate(data);
+          if (!v.ok) {
+            hfRunGate([], 0, v.reason);
+            return;
+          }
+          if (hfCurrentTimeline) {
+            hfCurrentTimeline.kill();
+            hfCurrentTimeline = null;
+          }
+          hfTeardown();
+          var layout = hfApplyStageConfig(data, v.durationS);
+          var tl = hfBuild(v.words, layout, v.durationS);
+          tl.set({}, {}, v.durationS); // pin timeline length to the data-derived duration
+          // GSAP quirk (confirmed 3.14.2): a fresh timeline already reports position 0,
+          // so seek(0) is treated as a no-op and skips rendering .set() calls scheduled
+          // at t=0 — the first frame would show pre-timeline CSS defaults (usually
+          // hidden). render(time, suppressEvents, force) with force=true bypasses that.
+          tl.render(0, true, true);
+          hfCurrentTimeline = tl;
+          window.__timelines = window.__timelines || {};
+          window.__timelines[HF_COMPOSITION_ID] = tl;
+          hfRunGate(v.words, v.durationS, null);
+        }
+        window.__HF_CAPTION_ATTACH__ = hfAttach;
+
+        (function hfBoot() {
+          function start(data) {
+            var ready =
+              document.fonts && document.fonts.ready ? document.fonts.ready : Promise.resolve();
+            ready.then(function () {
+              // A manual window.__HF_CAPTION_ATTACH__ call that lands while the
+              // sibling fetch / fonts.ready are still pending must win — never
+              // clobber it with the late-arriving boot payload.
+              if (hfCurrentTimeline) return;
+              hfAttach(data);
+            });
+          }
+          if (window.__HF_CAPTION__) {
+            start(window.__HF_CAPTION__);
+            return;
+          }
+          fetch("./caption-data.json")
+            .then(function (r) {
+              return r.ok ? r.json() : null;
+            })
+            .catch(function () {
+              return null;
+            })
+            .then(function (json) {
+              start(json || HF_DEMO_DATA);
+            });
+        })();
+      })();
     </script>
   </body>
 </html>