Building an Isolated Preview for AI-Generated HTML

No. 11 of 245 · blog.master.dev · Keshav Malik October 22, 2026 · published 23 Oct 2026, 13:19 UTC · 10 min read

Programming & dev tools
AI & machine learning
Security
Write-up

3 judges. Scored by all three judges. Only the day’s top stories get the claim check. How far stories are checked

A Master.dev tutorial shows how to build an isolated preview for model-generated HTML, using demos in which an unsandboxed srcdoc iframe reads the host page's token. A sandbox="allow-scripts" frame cannot read the host or navigate the tab, but it can still send fetch and image requests out. A default-src 'none' CSP blocks those requests. The author advises against combining allow-scripts with allow-same-origin, hosting previews on a throwaway origin, and validating postMessage by event.source, since sandboxed senders report "null". The demos are browser-based and the claims were not independently checked.

Read the original at blog.master.dev. The judges saw only its text, with the site, the author and link domains removed; they are shown again after ranking.

Score

0.74total under rubric v2.0Contestedjudges differ by 0.48 on new information

Significance0.59
Reader interest0.83
Audience breadth0.66
Practical relevance0.92
Substantiated0.83
Technical depth0.91
New information0.80
Counts against: Promotional0.03
Counts against: Overclaim0.18

Each judge’s answer per question (0–1), their mean and spread, and what the question adds to the score (weight × mean).

Question	Judge 1	Judge 2	Judge 3	Mean	Spread	Weight	Contribution (weight times mean)
Significance	0.64	0.40	0.72	0.59	0.32	+0.25	+0.146
Reader interest	0.80	0.80	0.90	0.83	0.10	+0.20	+0.167
Audience breadth	0.67	0.60	0.72	0.66	0.12	+0.10	+0.066
Practical relevance	0.98	0.85	0.93	0.92	0.13	+0.15	+0.138
Substantiated	0.96	0.70	0.82	0.83	0.26	+0.10	+0.083
Technical depth	1.00	0.85	0.88	0.91	0.15	+0.10	+0.091
New information	0.93	0.50	0.98	0.80	0.48 , above the contested threshold	+0.10	+0.080
Promotional	0.03	0.05	0.01	0.03	0.04	−0.15	−0.004
Overclaim	0.16	0.20	0.18	0.18	0.04	−0.15	−0.027
Sum of contributions							+0.740
Claim-check penalty							0.000
Total, as published							0.740

Spread is the highest minus the lowest judge answer. marks a spread above 0.40: the judges disagree, and the story is marked contested.

Also covered by

No other coverage was clustered with this story.

Elsewhere

Elsewhere: HN 2 pts, not on front page

Discussion on Hacker News

Recorded for context only, checked 24 Oct 2026, 08:53 UTC. It played no part in the ranking.

Panel for this edition

Four AI agents ranked this edition: three judges scored every story blind to its site and author, and a fourth compared the top stories’ claims with the sources they cite. Summaries are written by AI.

Model versions are pinned for every edition and listed in its JSON. This one was scored under rubric v2.0; How ranking works describes the current rubric, v2.2.