Fable’s intuition for iOS development is significantly worse than other areas I’ve used it in.
Great at infra, databases, web and more, just easily confused about how mobile apps work for some reason
2:25 PM · Jul 4, 2026 · 57.3K Views
T3 Stack creator Theo Browne says Fable excels at infrastructure but struggles with iOS mobile development
Story Overview
T3 Stack creator Theo Browne tested Anthropic's newly available Fable 5 on varied coding tasks and found reliable strength on infrastructure, databases, and web work while the same model quickly lost coherence on iOS projects.
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Developer Impact
Mobile codebases still trip frontier models
Early users report that opaque Apple frameworks leave less reliable signal for the model to follow, producing faster drift than on web or backend assignments.
Open Question
No public benchmarks yet clarify the gap
Launch materials emphasize long-horizon coding wins but omit mobile-specific evals, leaving builders to discover the iOS shortfall through direct use.
Sentiment
Positive users report strong experiences building iOS apps with Fable or similar models, while negative users criticize struggles with native mobile frameworks and iOS quirks.
Pos
51.6%
Neg
48.4%
31 comments with sentiment.
Cluster Engagement
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Theo - t3.gg@theo
Fwiw, Julius is usually more right than me
Julius@jullerino
The amount of world knowledge in Fable is insane. It’s navigating iOS simulators without any skills way better than codex with the OpenAI plugin 🤯
4hViews 9KLikes 28Bookmarks 6
REPLIES1
kache@yacineMTB
@theo Off the rails
Theo - t3.gg@theo
Fable’s intuition for iOS development is significantly worse than other areas I’ve used it in.
Great at infra, databases, web and more, just easily confused about how mobile apps work for some reason
7hViews 1KLikes 6Bookmarks 0
Luke@ldo_dev
@theo fable's just an android developer, dw about it
8hViews 407Likes 9
Juan Carlos Maggi@TheJuanMaggi
@theo I'm personally starting to hate React Native, feels like anything that is truly interactive should stay the hell out of RN. Going to try Godot and see how that goes.
6hViews 27Bookmarks 1
evie@shakily
@theo this is true. ive tried it on swift ui and it gives me this 😂
8hViews 257Likes 6
Yami C ‣ Software Engineer@debugging_yami
@saaslanee @theo My experience is the exact opposite: several models worked well when doing RN and Expo work. I've had great success with Sonnet 4.6, Opus, GPT-5.3 Codex, and even Gemma 4. I only had issues when trying Haiku for RN work.
RN evals is handy when choosing https://rn-evals.vercel.app/
7hViews 10Bookmarks 1
Martijn van der Wal@martijn_vdwal
@theo I’ve had pretty good luck with it, it’s was able to make a great animation of a custom-ish input field
Just curious, are you using the MCP? I know you don’t like many MCP’s, but this one is really helpful for iOS dev, especially in the new beta
7hViews 301Likes 1
dat1madguy 🇺🇸@dat1madguy
@theo GPT5.5 has been excellent for me for mobile app development
8hViews 162Likes 1
Ab.@Abiodun0x
@theo @Chiebuniem_
8hViews 222
saaslane@saaslanee
@theo all models has been the same for mobile development specially react native and expo apps
8hViews 32
Gabriel de Andrade@GabrielElpidio
Mobile is hard for every model; it feels like it needs quiet. A bit of guidance overall, but I've had great results in cleaning up the code and making architectural decisions. Just needs more guidance
I feel like most of it is just a lack of better tooling; sim-serve goes a long way, but not nearly enough
8hViews 201Likes 2
Eliot Gevers@EliotGevers
@aatxcus @theo uhm, what? show me your projects then
5hViews 17
Krax@Kraxkrokat
@theo I'm actually having *really* good experiences with it. What type of app are you trying to develop?
8hViews 494Likes 1
henry@h14hdotcom
@theo I have yet to find model that can get RN Reanimated & GestureHandler right without heavy steering.
8hViews 414Likes 1
Eloy@GoodieFX
@theo Now who is right?
7hViews 307Likes 1
Erdal@ErdalToprak
@theo yeah overusing geometry reader and lacks coherence on macos apps
8hViews 304Likes 1
Destiny Franks@desphixs
@theo mobile has so many hidden rules that web dev just doesn’t prepare you for
8hViews 261Likes 1
Robertg761@Robertg761_
@theo I've had good success with it for Android app development so far
8hViews 641
Christian Ciabattoni@chrislciaba
@theo It’s weirdly good at gtm stuff though. So much better than opus/5.5
8hViews 520
Irfan@iirfan
@theo 5.5 is really good
8hViews 104Likes 1
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