🗺️ RFC: Migrating OpenROM's UI from CustomTkinter to Flutter (v2.5 Roadmap)

[ClausValcaTD]

🗺️ RFC: Migrating OpenROM's UI from CustomTkinter to Flutter (v2.5 Roadmap)

Category: Ideas / Architecture

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Hey everyone 👋

I want to be transparent about a architectural direction we're planning for OpenROM v2.5, and I'd love to hear your thoughts before we commit to it.

What's changing — and what's NOT

What's staying:

• The entire core/ Python engine (converter, detector, validator) — untouched
• The CLI interface (coming in v2.2) — this becomes the backbone
• GPL v3 + Commons Clause license

What's changing:

• The UI layer only — replacing CustomTkinter with a Flutter frontend

That's it. The Python core isn't going anywhere.

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Why Flutter for the UI?

The current CustomTkinter interface works, but it has real limitations:

• It carries the full Tkinter/Tcl stack as a dependency — adds weight to the binary
• Rendering isn't native on any OS — it looks "off" especially on macOS
• No real animations or smooth transitions
• Hard to scale or maintain long-term

Flutter on desktop gives us:

• A single codebase that looks and feels consistent on Windows, macOS, and Linux
• Its own rendering engine — not dependent on OS widgets
• A much lighter distribution footprint when paired with a standalone CLI
• A clean separation between UI and logic

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The architecture after v2.5

┌─────────────────┐
│   Flutter UI    │  ← handles display, user input, drag & drop
└────────┬────────┘
         │ calls
┌────────▼────────┐
│  OpenROM CLI    │  ← openrom --input game.iso --format CHD
│  (Python)       │
└────────┬────────┘
         │ uses
┌────────▼────────┐
│  core/ engine   │  ← converter, detector, validator (unchanged)
│  (Python)       │
└─────────────────┘

The Flutter UI talks to the CLI — not to the Python core directly. This means:

• The CLI works fully standalone (automation, servers, scripts)
• The UI is replaceable — don't like Flutter? Build your own UI on top of the CLI
• The core stays stable and independent

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Roadmap leading to v2.5

Version	Focus
v2.1 ✅	Bug fixes, Commons Clause, per-job remove button
v2.2 🔜	CLI mode (openrom command), progress per-job, CHD info panel
v2.3 🔜	Conversion history, file rename before convert, estimated output size
v2.5 🎯	Flutter UI replaces CustomTkinter, talks to CLI

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What I want to hear from you

• Anyone with Flutter desktop experience — what are the real gotchas?
• Is there a better IPC approach between Flutter and the Python CLI? (stdout parsing, named pipes, local socket?)
• Would you prefer a different UI framework? (Tauri? Dear PyGui?)
• Any concerns about the split architecture?

This is an RFC — nothing is set in stone yet. If you have strong opinions, now is the time. 👇