prototype: GPUI front-end exploration in src-gpui/#7
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Sibling Rust crate that re-implements the ThoughtTree front end natively in Zed Industries' GPUI framework, kept separate from src-tauri/. Intended as a sketch for comparing GPUI ergonomics against the shipping React + Tauri build, not as a replacement. Includes: pure-Rust port of the graph domain model from src/lib/graph/ (types, mutations, conversation-path topo sort with synthesizer test), plus toolbar / canvas / side-panel views composed via Entity<AppState>. ACP integration is deliberately stubbed with a fake streaming reply so the prototype focuses on UI-framework comparison; src-gpui/README.md captures the trade-offs and the parts most likely to need API fix-ups against current Zed main. GPUI is a git-only dep requiring Metal/Vulkan and is not built in CI; this prototype has not been compiled. The graph/ submodule does compile and its test passes in isolation.
Pins the GPUI dep at zed-industries/zed @ 9155bf4 (HEAD on 2026-05-02)
instead of rev = "main". Walks the API drift the README anticipated.
Source-side cargo check is clean against the pinned rev. cargo run is
still blocked by Apple's Metal Toolchain no longer shipping with Xcode
26 by default; BUILD-NOTES.md captures what the user needs to install
to reach a runnable binary.
Drift fixed:
- theme.rs: rgb() is no longer const fn, replaced with a local
const fn hex(u32) -> Rgba so the color constants stay const.
- main.rs: Application::new() removed; switched to
gpui_platform::application() and added gpui_platform as a dep.
Imported gpui::prelude::* so cx.new(...) resolves AppContext.
- state.rs: Context::spawn now takes AsyncFnOnce(WeakEntity, &mut
AsyncApp); rewrote the simulate_stream closure as async move |...|
instead of |...| async move.
- views/canvas.rs: on_drag requires StatefulInteractiveElement;
added .id(node.id) on the node card to make it stateful, and
loosened render_node's return type to impl IntoElement.
- views/side_panel.rs: overflow_y_scroll requires stateful; added
.id("conversation-path") on the scroll container.
The graph/ submodule is unchanged; its test still passes via cargo
test once the Metal Toolchain blocker is cleared.
Two bugs in canvas.rs caused edges to render disconnected from nodes: 1. canvas() paint runs in window coordinates, but the previous code used raw (s.x, s.y) without adding bounds.origin. Cards live inside a relative-positioned container below the toolbar, so edges drew ~44 px above where the cards rendered. Added bounds.origin.x/y to each path coordinate. 2. Cards used .min_h(NODE_MIN_HEIGHT=80) so content-heavy nodes grew past 80 px, but edges anchored their source-y at pos.y + 80 — i.e. mid-card on tall cards. Switched to fixed .h(NODE_HEIGHT=120) + .overflow_hidden() so all cards are uniform and the source-bottom anchor is always correct. Renamed NODE_MIN_HEIGHT to NODE_HEIGHT to reflect that it is no longer a minimum. Verified against the seeded demo DAG: the two diagonal S-curves from u1 to a1/a2 and the converging curves from a1/a2 into the synth node now meet card edges cleanly.
Lifts gpui/examples/input.rs as src-gpui/src/views/text_input.rs: single-line input with IME, selection, mouse, clipboard. Wired into side_panel.rs as Edit/Save/Cancel button flow seeded from the selected node's content; commits via state.set_content. Bumps the crate to edition 2024 (the lifted code uses let chains) and adds unicode-segmentation for grapheme boundaries. Verified manually on Mac: edit → type → save updates the read-only display and the side-panel content; Send-to-agent stub then sees the edited text in its mock reply. Limits inherited from the example: single line (paste collapses newlines), no undo/redo, Esc not bound. Sufficient for the GPUI viability gate; multiline + word wrap is the next step.
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Summary
Sketch of what ThoughtTree's front end would look like rebuilt natively in
Zed Industries' GPUI
instead of React + Tauri. Lives in a new sibling crate
src-gpui/so theshipping
src-tauri/build is untouched.The point isn't a replacement — it's a concrete reference for comparing
GPUI ergonomics against the web stack.
src-gpui/README.mdcaptures thetrade-offs in detail.
What's in the prototype
src-gpui/src/graph/— pure-Rust port ofsrc/lib/graph/(types,mutations,
conversation_pathtopo sort with the synthesizersame-role-merge rule). Same domain language as
CONTEXT.md. Compilesclean and the synthesizer test passes.
src-gpui/src/state.rs—Entity<AppState>shared across views,filling the role of the Zustand store.
src-gpui/src/views/—ToolbarView,CanvasView(DAG cards +cubic-Bezier edges via
paint_path),SidePanelView(conversation-pathview with branch / send-to-agent actions).
src-gpui/src/state.rs::simulate_stream— fake streaming replyappended char-by-char on a background task, so the streaming render
loop is exercised without spawning ACP.
Deliberately out of scope
ACP integration, persistence, Markdown rendering, inline text editing,
auto-layout, settings, permissions dialog. README explains why each was
trimmed and where the real wiring would slot in.
Caveats
Metal/Vulkan, so it isn't built in this repo's CI and the prototype has
not been compiled. The graph submodule was verified to compile in
isolation (and its test passes).
Cargo.tomlusesrev = "main"for convenience; expect API drift on
cx.observe/cx.listenerclosure signatures,
PathBuilder, drag handlers, andWindowOptionsfields. README enumerates the likely fix-ups.
Initial impressions (full version in README)
GPUI lighter than React+Tauri at: one-language/one-process with no IPC
boundary, streaming updates without Tauri events, no bundler, state
sharing without prop drilling.
React+Tauri lighter than GPUI at: Markdown / rich-text rendering,
distribution (signed installers), API stability, devtools, talent pool.
Wash: raw rendering perf for graphs this size; DAG layout work
(both frameworks hand you a blank canvas for edge curves).
Test plan
src-gpui/Cargo.toml, runcargo run --releasefromsrc-gpui/,and chase whatever GPUI API errors fall out.
node selects it and updates the side panel, "Send to agent (stub)"
streams text into a new assistant node.
cargo teston thegraph/submodule passes (verified inisolation during prototype work).
https://claude.ai/code/session_017SrsAA3L9UitHCffzFmKAk
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