Animated loader · mercury-3

Output generated Cost / run $0.0311 Runtime 89.4s

Prompt for this run

Build a looping loading animation using the provided GSAP library. Use HTML, CSS, and JavaScript as needed. Write it to `index.html` in the current working directory using your file tools. Inline your own CSS and JavaScript. Do not use external assets, CDNs, or network requests. Use the provided `gsap.min.js` (global `gsap`) through a plain local script tag; the runner will inline it into the final artifact. Required behavior: - On a dark background, show a group of rounded geometric shapes that smoothly change scale, position, and corner radius, plus a row of five dots with staggered motion or opacity. - Coordinate both elements using a GSAP timeline with smooth easing. The full sequence lasts 3 to 6 seconds and repeats without an abrupt jump or a growing number of animation instances. - Provide Pause/Resume and Restart controls. Pause freezes the current timeline position; Resume continues from it; Restart returns to the beginning. - Center the composition and keep it visible at the supplied viewport. Use HTML/CSS or inline SVG; no external assets or paid GSAP plugins are available. - Choose the palette and detailed choreography freely. No backend loading operation is required. Verify: Sample the timeline at several moments to inspect shape changes, staggered dot motion, and smooth transitions. Pause and resume to check that animation continues from the paused state, then use Restart and check the starting composition.

⛨ sandboxed Open in new tab ↗

TAKE IT TO CODE

A single self-contained HTML file — copy it and open in any browser, or reuse the prompt with your own pi-agent run.

RUN

modelmercury-3

vendorInception

harnesspi 0.87.1 · browser iteration

generated2026-10-23

METRICS

runtime89.4s

tokens in1594k

tokens out21k

cached1509k

cost / run$0.0311

Transcript · 105 messages

system

user

assistant

→ bash {"command":"ls -la /tmp/job-CBitBa/"}

toolResult

total 84 drwx------ 3 node node 4096 Oct 23 09:53 . drwxrwxrwt 8 root root 4096 Oct 23 09:53 .. drwxr-xr-x 3 node node 4096 Oct 23 09:53 .home -rw-r--r-- 1 node node 72214 Oct 23 09:53 gsap.min.js

assistant

→ bash

{"command":"head -c 500 /tmp/job-CBitBa/gsap.min.js; echo; grep -o 'version:\"[^\"]*\"' /tmp/job-CBitBa/gsap.min.js | head -5"}

toolResult

/*! * GSAP 3.12.5 * https://gsap.com * * @license Copyright 2024, GreenSock. All rights reserved. * Subject to the terms at https://gsap.com/standard-license or for Club GSAP members, the agreement issued with that membership. * @author: Jack Doyle, jack@greensock.com */ !function(t,e){"object"==typeof exports&&"undefined"!=typeof module?e(exports):"function"==typeof define&&define.amd?define(["exports"],e):e((t=t||self).window=t.window||{})}(this,function(e){"use strict";function _inhe

assistant

→ write /tmp/job-CBitBa/index.html (7059 bytes)

toolResult

Successfully wrote to /tmp/job-CBitBa/index.html

assistant

→ browser {"action":"reload"}

toolResult

{"console":[],"dom":"Pause\nResume\nRestart","images":"model does not support images"}

assistant

→ browser {"action":"inspect"}

toolResult

{"console":[],"dom":"Pause\nResume\nRestart","images":"model does not support images"}

assistant

→ browser {"action":"screenshot"}

toolResult

{"console":[],"dom":"Pause\nResume\nRestart","images":"model does not support images"}

assistant

→ bash

{"command":"cd /tmp/job-CBitBa && node --version 2>/dev/null; python3 --version 2>/dev/null; ls node_modules 2>/dev/null | head; which npm"}

toolResult

v24.18.0 /usr/local/bin/npm

assistant

I'll add a temporary on-screen diagnostic readout to sample the timeline state (since screenshot images aren't viewable in this session), then remove it after verification.

→ edit

{"path":"/tmp/job-CBitBa/index.html","edits":[{"oldText":"      // Initial state: running.\n      setActive(btnResume, true);","newText":"

toolResult

Successfully replaced 1 block(s) in /tmp/job-CBitBa/index.html.

assistant

→ browser {"action":"reload"}

toolResult

{"console":[],"dom":"Pause\nResume\nRestart\nt=0.10 p=0.021 paused=false\n0: matrix(1.0012, 0, 0, 1.0012, 0.1238, -0.0991) r=26px\n1: none r=20px\n2: none r=24px\nDOTS:\nnone o=0.25\nnone o=0.25\nnone o=0.25\nnone o=0.25\nnone o=0.25","images":"model does not support images"}

assistant

→ bash {"command":"sleep 1.2"}

toolResult

(no output)

assistant

→ browser {"action":"inspect"}

toolResult

{"console":[],"dom":"Pause\nResume\nRestart\nt=4.11 p=0.894 paused=false\n0: matrix(1.016, 0, 0, 1.016, -2.1331, 1.2799) r=28px\n1: matrix(1.0304, 0, 0, 1.0304, 6.6959, -5.4785) r=25px\n2: matrix(1.1147, 0, 0, 1.1147, -6.12, 15.3) r=36px\nDOTS:\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25","images":"model does not support images"}

assistant

→ bash {"command":"sleep 3.0"}

toolResult

(no output)

assistant

→ browser {"action":"inspect"}

toolResult

{"console":[],"dom":"Pause\nResume\nRestart\nt=0.03 p=0.006 paused=false\n0: matrix(1, 0, 0, 1, 0.0031, -0.0025) r=26px\n1: matrix(1, 0, 0, 1, 0, 0) r=20px\n2: matrix(1, 0, 0, 1, 0, 0) r=24px\nDOTS:\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25","images":"model does not support images"}

assistant

→ bash {"command":"sleep 0.5"}

toolResult

(no output)

assistant

→ browser {"action":"inspect"}

toolResult

{"console":[],"dom":"Pause\nResume\nRestart\nt=2.16 p=0.470 paused=false\n0: matrix(0.8588, 0, 0, 0.8588, -12.24, 13.77) r=17px\n1: matrix(0.861, 0, 0, 0.861, 16.679, -12.9725) r=13px\n2: matrix(0.9002, 0, 0, 0.9002, 23.9574, 9.9823) r=16px\nDOTS:\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25","images":"model does not support images"}

assistant

→ edit

{"path":"/tmp/job-CBitBa/index.html","edits":[{"oldText":"      tl.eventCallback(\"onUpdate\", function () {\n        diag.textContent = \"t

toolResult

Successfully replaced 1 block(s) in /tmp/job-CBitBa/index.html.

assistant

→ browser {"action":"reload"}

toolResult

{"console":[],"dom":"Pause\nResume\nRestart\nt=0.09 p=0.019 paused=false\n0: matrix(1.0009, 0, 0, 1.0009, 0.0922, -0.0737) r=26px\n1: none r=20px\n2: none r=24px\nDOTS:\nnone o=0.25\nnone o=0.25\nnone o=0.25\nnone o=0.25\nnone o=0.25","images":"model does not support images"}

assistant

→ bash {"command":"sleep 0.3"}

toolResult

(no output)

assistant

→ browser {"action":"inspect"}

toolResult

{"console":[],"dom":"Pause\nResume\nRestart\nAUTOSAMPLES\nt=0\n0: matrix(1, 0, 0, 1, 0, 0) r=26px\n1: none r=20px\n2: none r=24px\nDOTS:\nnone o=0.25\nnone o=0.25\nnone o=0.25\nnone o=0.25\nnone o=0.25\n---\nt=0.3\n0: matrix(1.0378, 0, 0, 1.0378, 3.779, -3.0232) r=30px\n1: matrix(1.0046, 0, 0, 1.0046, -0.5185, 0.4444) r=21px\n2: matrix(1, 0, 0, 1, 0, 0) r=24px\nDOTS:\nmatrix(1, 0, 0, 1, 0, -1.7188) o=0.3216\nmatrix(1, 0, 0, 1, 0, -0.071) o=0.253\nnone o=0.25\nnone o=0.25\nnone o=0.25\n---\nt=0.65\n0: matrix(1.2622, 0, 0, 1.2622, 26.221, -20.9768) r=54px\n1: matrix(1.1622, 0, 0, 1.1622, -18.1674, 15.572) r=39px\n2: matrix(1.0471, 0, 0, 1.0471, -3.2936, -5.1756) r=29px\nDOTS:\nmatrix(1, 0, 0, 1, 0, -17.5595) o=0.9816\nmatrix(1, 0, 0, 1, 0, -15.1609) o=0.8817\nmatrix(1, 0, 0, 1, 0, -11.2382) o=0.7183\nmatrix(1, 0, 0, 1, 0, -6.7618) o=0.5317\nmatrix(1, 0, 0, 1, 0, -2.8391) o=0.3683\n---\nt=1.25\n0: matrix(1.2259, 0, 0, 1.2259, 23.1852, -17.7778) r=51px\n1: matrix(1.2324, 0, 0, 1.2324, -25.9808, 22.332) r=48px\n2: matrix(1.1998, 0, 0, 1.1998, -13.9739, -21.9781) r=46px\nDOTS:\nmatrix(1, 0, 0, 1, 0, -14.2901) o=0.8454\nmatrix(1, 0, 0, 1, 0, -17.1434) o=0.9643\nmatrix(1, 0, 0, 1, 0, -18) o=1\nmatrix(1, 0, 0, 1, 0, -18) o=1\nmatrix(1, 0, 0, 1, 0, -18) o=1\n---\nt=1.55\n0: matrix(0.8741, 0, 0, 0.8741, -9.1852, 11.7778) r=21px\n1: matrix(0.9905, 0, 0, 0.9905, 1.8464, -0.6557) r=25px\n2: matrix(1.1294, 0, 0, 1.1294, -5.0604, -14.4719) r=39px\nDOTS:\nmatrix(1, 0, 0, 1, 0, -0.4405) o=0.2684\nmatrix(1, 0, 0, 1, 0, -2.8391) o=0.3683\nmatrix(1, 0, 0, 1, 0, -6.7618) o=0.5317\nmatrix(1, 0, 0, 1, 0, -11.2382) o=0.7183\nmatrix(1, 0, 0, 1, 0, -15.1609) o=0.8817\n---\nt=2.35\n0: matrix(0.9973, 0, 0, 0.9973, -3.375, 3.7969) r=23px\n1: matrix(0.925, 0, 0, 0.925, 9, -7) r=16px\n2: matrix(0.9122, 0, 0, 0.9122, 21.0703, 8.7793) r=17px\nDOTS:\nmatrix(1, 0, 0, 1, 0, 3) o=0.3875\nmatrix(1, 0, 0, 1, 0, 0.7023) o=0.2822\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\n---\nt=2.75\n0: matrix(1.0505, 0, 0, 1.0505, -0.1097, 0.0658) r=26px\n1: matrix(1, 0, 0, 1, 0, 0) r=20px\n2: matrix(0.9974, 0, 0, 0.9974, 0.6328, 0.2637) r=24px\nDOTS:\nmatrix(1, 0, 0, 1, 0, 12) o=0.8\nmatrix(1, 0, 0, 1, 0, 12) o=0.8\nmatrix(1, 0, 0, 1, 0, 11.4813) o=0.7762\nmatrix(1, 0, 0, 1, 0, 9.3552) o=0.6788\nmatrix(1, 0, 0, 1, 0, 6.2094) o=0.5346\n---\nt=3.45\n0: matrix(1.1495, 0, 0, 1.1495, -19.8903, 11.9342) r=44px\n1: matrix(1.0956, 0, 0, 1.0956, 21.0343, -17.2099) r=37px\n2: matrix(1.1147, 0, 0, 1.1147, -6.118, 15.2949) r=36px\nDOTS:\nmatrix(1, 0, 0, 1, 0, 0.3618) o=0.2666\nmatrix(1, 0, 0, 1, 0, 2.306) o=0.3557\nmatrix(1, 0, 0, 1, 0, 5.3728) o=0.4963\nmatrix(1, 0, 0, 1, 0, 8.6302) o=0.6456\nmatrix(1, 0, 0, 1, 0, 11.0883) o=0.7582\n---\nt=4.45\n0: matrix(1, 0, 0, 1, 0, 0) r=26px\n1: matrix(1, 0, 0, 1, 0, 0) r=20px\n2: matrix(1.004, 0, 0, 1.004, -0.2109, 0.5273) r=24px\nDOTS:\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25","images":"model does not support images"}

assistant

→ browser {"action":"click","x":545,"y":650}

toolResult

assistant

→ browser {"action":"click","x":490,"y":587}

toolResult

assistant

→ edit

{"path":"/tmp/job-CBitBa/index.html","edits":[{"oldText":"        [0, 0.3, 0.65, 1.25, 1.55, 2.35, 2.75, 3.45, 4.45].forEach(sampleAt);\n

toolResult

Successfully replaced 1 block(s) in /tmp/job-CBitBa/index.html.

assistant

→ browser {"action":"reload"}

toolResult

{"console":[],"dom":"Pause\nResume\nRestart\nAUTOSAMPLES\nBTN btn-pause: x=462 y=593 w=77 h=36\n---\nBTN btn-resume: x=552 y=593 w=90 h=36\n---\nBTN btn-restart: x=653 y=593 w=84 h=36\n---\nt=0\n0: matrix(1, 0, 0, 1, 0, 0) r=26px\n1: none r=20px\n2: none r=24px\nDOTS:\nnone o=0.25\nnone o=0.25\nnone o=0.25\nnone o=0.25\nnone o=0.25\n---\nt=0.3\n0: matrix(1.0378, 0, 0, 1.0378, 3.779, -3.0232) r=30px\n1: matrix(1.0046, 0, 0, 1.0046, -0.5185, 0.4444) r=21px\n2: matrix(1, 0, 0, 1, 0, 0) r=24px\nDOTS:\nmatrix(1, 0, 0, 1, 0, -1.7188) o=0.3216\nmatrix(1, 0, 0, 1, 0, -0.071) o=0.253\nnone o=0.25\nnone o=0.25\nnone o=0.25\n---\nt=0.65\n0: matrix(1.2622, 0, 0, 1.2622, 26.221, -20.9768) r=54px\n1: matrix(1.1622, 0, 0, 1.1622, -18.1674, 15.572) r=39px\n2: matrix(1.0471, 0, 0, 1.0471, -3.2936, -5.1756) r=29px\nDOTS:\nmatrix(1, 0, 0, 1, 0, -17.5595) o=0.9816\nmatrix(1, 0, 0, 1, 0, -15.1609) o=0.8817\nmatrix(1, 0, 0, 1, 0, -11.2382) o=0.7183\nmatrix(1, 0, 0, 1, 0, -6.7618) o=0.5317\nmatrix(1, 0, 0, 1, 0, -2.8391) o=0.3683\n---\nt=1.25\n0: matrix(1.2259, 0, 0, 1.2259, 23.1852, -17.7778) r=51px\n1: matrix(1.2324, 0, 0, 1.2324, -25.9808, 22.332) r=48px\n2: matrix(1.1998, 0, 0, 1.1998, -13.9739, -21.9781) r=46px\nDOTS:\nmatrix(1, 0, 0, 1, 0, -14.2901) o=0.8454\nmatrix(1, 0, 0, 1, 0, -17.1434) o=0.9643\nmatrix(1, 0, 0, 1, 0, -18) o=1\nmatrix(1, 0, 0, 1, 0, -18) o=1\nmatrix(1, 0, 0, 1, 0, -18) o=1\n---\nt=1.55\n0: matrix(0.8741, 0, 0, 0.8741, -9.1852, 11.7778) r=21px\n1: matrix(0.9905, 0, 0, 0.9905, 1.8464, -0.6557) r=25px\n2: matrix(1.1294, 0, 0, 1.1294, -5.0604, -14.4719) r=39px\nDOTS:\nmatrix(1, 0, 0, 1, 0, -0.4405) o=0.2684\nmatrix(1, 0, 0, 1, 0, -2.8391) o=0.3683\nmatrix(1, 0, 0, 1, 0, -6.7618) o=0.5317\nmatrix(1, 0, 0, 1, 0, -11.2382) o=0.7183\nmatrix(1, 0, 0, 1, 0, -15.1609) o=0.8817\n---\nt=2.35\n0: matrix(0.9973, 0, 0, 0.9973, -3.375, 3.7969) r=23px\n1: matrix(0.925, 0, 0, 0.925, 9, -7) r=16px\n2: matrix(0.9122, 0, 0, 0.9122, 21.0703, 8.7793) r=17px\nDOTS:\nmatrix(1, 0, 0, 1, 0, 3) o=0.3875\nmatrix(1, 0, 0, 1, 0, 0.7023) o=0.2822\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\n---\nt=2.75\n0: matrix(1.0505, 0, 0, 1.0505, -0.1097, 0.0658) r=26px\n1: matrix(1, 0, 0, 1, 0, 0) r=20px\n2: matrix(0.9974, 0, 0, 0.9974, 0.6328, 0.2637) r=24px\nDOTS:\nmatrix(1, 0, 0, 1, 0, 12) o=0.8\nmatrix(1, 0, 0, 1, 0, 12) o=0.8\nmatrix(1, 0, 0, 1, 0, 11.4813) o=0.7762\nmatrix(1, 0, 0, 1, 0, 9.3552) o=0.6788\nmatrix(1, 0, 0, 1, 0, 6.2094) o=0.5346\n---\nt=3.45\n0: matrix(1.1495, 0, 0, 1.1495, -19.8903, 11.9342) r=44px\n1: matrix(1.0956, 0, 0, 1.0956, 21.0343, -17.2099) r=37px\n2: matrix(1.1147, 0, 0, 1.1147, -6.118, 15.2949) r=36px\nDOTS:\nmatrix(1, 0, 0, 1, 0, 0.3618) o=0.2666\nmatrix(1, 0, 0, 1, 0, 2.306) o=0.3557\nmatrix(1, 0, 0, 1, 0, 5.3728) o=0.4963\nmatrix(1, 0, 0, 1, 0, 8.6302) o=0.6456\nmatrix(1, 0, 0, 1, 0, 11.0883) o=0.7582\n---\nt=4.45\n0: matrix(1, 0, 0, 1, 0, 0) r=26px\n1: matrix(1, 0, 0, 1, 0, 0) r=20px\n2: matrix(1.004, 0, 0, 1.004, -0.2109, 0.5273) r=24px\nDOTS:\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25\nmatrix(1, 0, 0, 1, 0, 0) o=0.25","images":"model does not support images"}

assistant

→ browser {"action":"click","x":500,"y":611}

toolResult

assistant

→ bash {"command":"sleep 0.25"}

toolResult

(no output)

assistant

→ browser {"action":"inspect"}

toolResult

assistant

→ edit

{"path":"/tmp/job-CBitBa/index.html","edits":[{"oldText":"      function logCtrl(msg) {\n        ctl.textContent = msg + \"\\nt=\" + tl.time

toolResult

Successfully replaced 1 block(s) in /tmp/job-CBitBa/index.html.

assistant

→ browser {"action":"reload"}

toolResult

assistant

→ bash {"command":"sleep 0.3"}

toolResult

(no output)

assistant

→ browser {"action":"inspect"}

toolResult

assistant

→ browser {"action":"click","x":500,"y":611}

toolResult

assistant

→ bash {"command":"sleep 0.6"}

toolResult

(no output)

assistant

→ browser {"action":"inspect"}

toolResult

assistant

→ bash {"command":"sleep 1.0"}

toolResult

(no output)

assistant

→ browser {"action":"inspect"}

toolResult

assistant

→ browser {"action":"click","x":597,"y":611}

toolResult

assistant

→ bash {"command":"sleep 0.5"}

toolResult

(no output)

assistant

→ browser {"action":"inspect"}

toolResult

assistant

→ browser {"action":"click","x":500,"y":611}

toolResult

assistant

→ bash {"command":"sleep 0.6"}

toolResult

(no output)

assistant

→ browser {"action":"inspect"}

toolResult

assistant

→ browser {"action":"click","x":597,"y":611}

toolResult

assistant

→ bash {"command":"sleep 0.3"}

toolResult

(no output)

assistant

→ browser {"action":"inspect"}

toolResult

assistant

→ browser {"action":"click","x":695,"y":611}

toolResult

assistant

→ bash {"command":"sleep 0.4"}

toolResult

(no output)

assistant

→ browser {"action":"inspect"}

toolResult

assistant

All controls are verified. Now I'll remove the temporary diagnostics and write the final clean file.

→ write /tmp/job-CBitBa/index.html (7059 bytes)

toolResult

Successfully wrote to /tmp/job-CBitBa/index.html

assistant

→ browser {"action":"reload"}

toolResult

{"console":[],"dom":"Pause\nResume\nRestart","images":"model does not support images"}

assistant

→ bash

{"command":"cd /tmp/job-CBitBa && ls -la index.html && grep -c \"http\" index.html; grep -n \"gsap.min.js\" index.html; node --check <(sed -

toolResult

-rw-r--r-- 1 node node 7065 Oct 23 09:55 index.html 0 151: <script src="gsap.min.js"></script> node:fs:441 return binding.readFileUtf8(path, stringToFlags(options.flag)); ^ Error: ENOENT: no such file or directory, open '/proc/441/fd/pipe:[2777]' at Object.readFileSync (node:fs:441:20) at node:internal/main/check_syntax:36:21 { errno: -2, code: 'ENOENT', syscall: 'open', path: '/proc/441/fd/pipe:[2777]' } Node.js v24.18.0 Command exited with code 1

assistant

→ bash

{"command":"cd /tmp/job-CBitBa && sed -n '/<script>/,/<\\/script>/p' index.html | sed '1d;$d' > /tmp/check.js && node --check /tmp/check.js

toolResult

JS syntax OK 0

assistant

Done. Final artifact: `/tmp/job-CBitBa/index.html` (single self-contained file, inline CSS/JS, loads the provided `gsap.min.js` via a plain local `<script>` tag; zero external URLs). ## What I built - **Dark radial-gradient background**, composition centered via flexbox (shapes cluster, five-dot row, controls). - **GSAP timeline** (`repeat: -1`, single timeline — no dynamically growing instance count): - 3 rounded shapes (red/teal/yellow) morph **scale, x/y position, and border-radius** across 5 segments each, always returning to the exact starting state. - 5 dots pulse with `stagger: 0.08` waves (y-offset + opacity). - Total loop ≈ 4.6s, power2.inOut / sine.inOut easing. - **Controls**: Pause (`tl.pause()`), Resume (`tl.resume()`), Restart (`tl.restart()`), with active-button styling. ## What I verified (browser runs, via computed-style sampling) - **No console errors** on load; animation runs from base composition at t=0. - **Timeline sampling at 9 moments** (0, .3, .65, 1.25, 1.55, 2.35, 2.75, 3.45, 4.45s): shapes show distinct, smoothly interpolated scale/position/corner-radius values; dots show clear staggered motion (e.g. at t=0.65: dot Y offsets −17.6/−15.2/−11.2/−6.8/−2.8px with opacities 0.98/0.88/0.72/0.53/0.37). - **Seamless loop**: sample at 4.45s ≈ sample at 0s (identical starting composition) — no jump. - **Pause** froze the current position (t stayed constant while wall-clock advanced); **Resume** continued from that same position (t advanced from the frozen value, not a reset); **Restart** returned to near t=0 and kept looping. ## Unverified - Visual rendering (this model cannot view screenshots — `"model does not support images"`), so I sampled computed CSS values instead of pixels. - Cross-browser behavior beyond the harness browser; very-long-uptime memory growth (beyond several loop iterations) wasn't measured.