From 6b7dea887dfbf1b3b787108ac733a12306c32493 Mon Sep 17 00:00:00 2001
From: Carlos Alcaraz <193642530+calcarazgre646@users.noreply.github.com>
Date: Thu, 18 Jun 2026 21:56:55 -0300
Subject: [PATCH] fix(runtime): guard dotlottie v1 seek against zero duration

The dotlottie-web v1 seek branch computed (time / duration) * 100 with
duration = anim.duration ?? 1. Nullish coalescing does not replace 0, so
a player reporting duration 0 (not yet loaded, the bootstrap-time
discover->seek window) produced (time / 0) * 100 = NaN, and seek(NaN)
blanked the first frame at composition time 0. The v2 branch right above
already guards with if (totalFrames > 0).

Mirror that guard: default duration to 0 and seek only when it is
positive, with the percentage clamped to [0, 100].
---
 .../core/src/runtime/adapters/lottie.test.ts  | 21 +++++++++++++++++++
 packages/core/src/runtime/adapters/lottie.ts  | 14 +++++++++----
 2 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/packages/core/src/runtime/adapters/lottie.test.ts b/packages/core/src/runtime/adapters/lottie.test.ts
index a8e5eb4a53..b3f5402149 100644
--- a/packages/core/src/runtime/adapters/lottie.test.ts
+++ b/packages/core/src/runtime/adapters/lottie.test.ts
@@ -121,6 +121,27 @@ describe("lottie adapter", () => {
       adapter.seek({ time: -5 });
       expect(anim.goToAndStop).toHaveBeenCalledWith(0, false);
     });
+
+    it("seeks a v1 dotlottie player by percentage when duration is known", () => {
+      // v1 player: has seek() but no setCurrentRawFrameValue.
+      const seek = vi.fn();
+      const player = { play: vi.fn(), pause: vi.fn(), duration: 4, seek };
+      lottieWindow.__hfLottie = [player];
+      const adapter = createLottieAdapter();
+      adapter.seek({ time: 1 }); // 1 / 4 * 100 = 25
+      expect(seek).toHaveBeenCalledWith(25);
+    });
+
+    it("does not seek a v1 dotlottie player whose duration is 0 (not yet loaded)", () => {
+      // duration 0 before load: an unguarded (time / 0) * 100 = NaN used to
+      // reach seek() and blank the first frame at composition time 0.
+      const seek = vi.fn();
+      const player = { play: vi.fn(), pause: vi.fn(), duration: 0, seek };
+      lottieWindow.__hfLottie = [player];
+      const adapter = createLottieAdapter();
+      adapter.seek({ time: 0 });
+      expect(seek).not.toHaveBeenCalled();
+    });
   });
 
   describe("pause", () => {
diff --git a/packages/core/src/runtime/adapters/lottie.ts b/packages/core/src/runtime/adapters/lottie.ts
index e304f61f76..5a303dc74e 100644
--- a/packages/core/src/runtime/adapters/lottie.ts
+++ b/packages/core/src/runtime/adapters/lottie.ts
@@ -102,10 +102,16 @@ export function createLottieAdapter(): RuntimeDeterministicAdapter {
                 anim.setCurrentRawFrameValue(Math.min(frame, totalFrames - 1));
               }
             } else if (typeof anim.seek === "function") {
-              // dotlottie-web v1: seek(percentage 0-100)
-              const duration = anim.duration ?? 1;
-              const percentage = Math.min(100, (time / duration) * 100);
-              anim.seek(percentage);
+              // dotlottie-web v1: seek(percentage 0-100). Mirror the v2 guard
+              // above: a not-yet-loaded player reports duration 0, and `0 ?? 1`
+              // stays 0 (nullish coalescing does not replace 0), so an unguarded
+              // (time / 0) * 100 = NaN reached seek() and blanked the first frame
+              // at composition time 0.
+              const duration = anim.duration ?? 0;
+              if (duration > 0) {
+                const percentage = Math.max(0, Math.min(100, (time / duration) * 100));
+                anim.seek(percentage);
+              }
             }
           }
         } catch (err) {