The append-only AST trick that makes Flutter AI chat actually smooth
A new technique has been developed to enhance the performance of Flutter AI chat applications. This method utilizes an append-only Abstract Syntax Tree (AST) to prevent UI glitches during streamed responses. The solution has been packaged as 'streamdown', which significantly improves rendering speed and stability.
- ▪The append-only AST trick allows for smoother rendering in Flutter AI chat applications.
- ▪The solution addresses issues like code blocks flashing and scroll position breaking during streamed responses.
- ▪The 'streamdown' package is a drop-in replacement that is 188 times faster on chunked input.
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| Original publisher | DEV.to (Top) |
| Canonical URL | https://dev.to/jay_limbani_5de2aceb239f0/the-append-only-ast-trick-that-makes-flutter-ai-chat-actually-smooth-1c00 |
| Publication time | Sat, 23 May 2026 06:27:44 +0000 |
| Retrieval time | 2026-05-23T06:37:24.939Z |
| Last seen | 2026-05-23T06:37:24.939Z |
| Headline source | Publisher (no WeSearch rewrite) |
| Excerpt source | publisher body |
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| Summary | WeSearch · cerebras-chat (WeSearch summarizer) |
| Summary source text | contentText |
| Citation coverage | Summary is a WeSearch-generated derivative; primary citation is the original publisher URL. |
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| AI summary | May WeSearch generate its own short summary of the article? | Limited |
| Retrieval / RAG | May the content be exposed for third-party retrieval-augmented generation? | Not asserted |
| Model training | May the content be used to train AI models? | Not asserted |
| Commercial reuse | May the content be reused commercially? | Not permitted |
Basis: Derived from the published RSS/Atom feed. Contact: [email protected]. Reviewed: 2026-07-24.
Opening excerpt (first ~120 words) tap to expand
try { if(localStorage) { let currentUser = localStorage.getItem('current_user'); if (currentUser) { currentUser = JSON.parse(currentUser); if (currentUser.id === 3947184) { document.getElementById('article-show-container').classList.add('current-user-is-article-author'); } } } } catch (e) { console.error(e); } jay limbani Posted on May 23 • Originally published at github.com The append-only AST trick that makes Flutter AI chat actually smooth #flutter #dart #ai #opensource — flutter_markdown re-parses the entire response string on every streamed token. The fix is an append-only AST with monotonic node IDs used as Flutter widget keys. I packaged it as streamdown — a drop-in replacement that's 188× faster on chunked input and produces zero visible flicker. Live on pub.dev today.
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