[Devvit Web] "height: tall" not respected for inline posts on Reddit mobile app (iOS/Android)

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
45/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Quiet
Tech stack
typescript

Research direction

Start with the Devvit Web inline post handling and the devvit.json post configuration shown in the issue; reproduce the height difference on Reddit iOS or Android and compare it with the old addCustomPostType({ height: 'tall' }) behavior. Done means an inline post configured with height: "tall" renders at 512px on mobile in both the feed and post detail page without regressing desktop behavior.

Written by the indexing model from the issue text.

Description

Summary
Inline webview posts configured with "height": "tall" in devvit.json render at a significantly smaller height than 512px on the Reddit iOS and Android apps. The post appears short/clipped in both the feed and on the post detail page.

Expected behaviour
Post renders at 512px ("tall") height inline, matching the behaviour of the old addCustomPostType({ height: 'tall' }) Blocks API.

Actual behaviour
Post renders at a noticeably smaller height (~350px or less) on mobile. Desktop appears unaffected.

devvit.json config
"post": { "dir": "dist/client", "entrypoints": { "default": { "entry": "index.html", "height": "tall", "inline": true } } }

CSS approaches tried, all fail on mobile

height: 100% on html, body, #root (per official template)
height: 100vh
position: fixed; inset: 0 on body
window.innerHeight read at runtime as explicit px height
Hardcoded height: 512px on all elements
Additional context

Posts created with the old addCustomPostType({ height: 'tall' }) Blocks API render at the correct height — this is a regression specific to the new Devvit Web post type
@devvit/public-api version: 0.12.17
Reproducible on iOS Reddit app

Dominant language
TypeScript
Stars
210
Forks
88
PR merge metrics
No merged PRs in 30d

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