feat(gpui): gpui render backend and the macos-app target with native text layout

.github/workflows/macos.yml

@@ -0,0 +1,111 @@
+name: macOS gpui backend
+
+# The first macOS lane in CI: the gpui backend (engine/backends/gpui) and
+# the macos-app host (hosts/macos) are standalone crates excluded from the
+# ubuntu release workspace, so this is the only place they build. The lane
+# also runs the TS surfaces its path filter watches (contract drift, the
+# platform/note/font-bake tests, and a real macos-app plan+bundle build of
+# the note). gpui needs a window server for anything more; runtime behavior
+# is pinned by the note --proof acceptance run (docs/BACKENDS.md).
+
+on:
+  pull_request:
+    paths:
+      - ".github/workflows/macos.yml"
+      - "contracts/spec/**"
+      - "engine/core/**"
+      - "engine/crates/pocket-ui-surface/**"
+      - "engine/backends/gpui/**"
+      - "hosts/macos/**"
+      - "tools/macos.ts"
+      - "apps/note/**"
+      - "framework/compiler/**"
+      - "assets/fonts/**"
+      - "tests/platform-contracts.test.ts"
+      - "tests/note.test.ts"
+      - "tests/font-bake.test.ts"
+      - "tests/npm-package.test.ts"
+      - "package.json"
+  push:
+    branches: [main]
+    paths:
+      - ".github/workflows/macos.yml"
+      - "contracts/spec/**"
+      - "engine/core/**"
+      - "engine/crates/pocket-ui-surface/**"
+      - "engine/backends/gpui/**"
+      - "hosts/macos/**"
+      - "tools/macos.ts"
+      - "apps/note/**"
+      - "framework/compiler/**"
+      - "assets/fonts/**"
+      - "tests/platform-contracts.test.ts"
+      - "tests/note.test.ts"
+      - "tests/font-bake.test.ts"
+      - "tests/npm-package.test.ts"
+      - "package.json"
+  workflow_dispatch: {}
+
+permissions:
+  contents: read
+
+jobs:
+  rust:
+    name: gpui backend + host
+    runs-on: macos-latest
+    timeout-minutes: 30
+    steps:
+      - uses: actions/checkout@v7
+
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: clippy, rustfmt
+          # note.test.ts boots the sim host, which builds the wasm core.
+          targets: wasm32-unknown-unknown
+
+      - uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: |
+            engine/backends/gpui
+            hosts/macos
+            engine/wasm
+
+      - uses: oven-sh/setup-bun@v2
+
+      - name: Install JS dependencies
+        run: bun install --frozen-lockfile
+
+      - name: Contract + note + platform + npm package tests
+        run: bun test tests/platform-contracts.test.ts tests/note.test.ts tests/font-bake.test.ts tests/npm-package.test.ts && bun tests/contract.ts
+
+      - name: Compile the note against macos-app (plan + bundle + pak)
+        run: |
+          bun -e '
+          import { validateAndResolveBuildPlan } from "./framework/src/manifest/resolve.ts";
+          import { mkdirSync } from "node:fs";
+          const m = await Bun.file("apps/note/pocket.json").json();
+          const r = validateAndResolveBuildPlan(m, { target: "macos-app" });
+          if (!r.ok) throw new Error(JSON.stringify(r.diagnostics));
+          mkdirSync(".pocket/macos-app", { recursive: true });
+          await Bun.write(".pocket/macos-app/note-main.plan.json", JSON.stringify(r.plan, null, 2) + "\n");'
+          bun tools/build.ts --plan=.pocket/macos-app/note-main.plan.json
+
+      - name: Test core (TEXT_RUN + native measure gates)
+        run: cargo test --locked --manifest-path engine/core/Cargo.toml
+
+      - name: Test ui surface (svcOpen deny-by-default, string ops)
+        run: cargo test --locked --manifest-path engine/Cargo.toml -p pocket-ui-surface
+
+      - name: rustfmt
+        run: |
+          cargo fmt --check --manifest-path engine/backends/gpui/Cargo.toml
+          cargo fmt --check --manifest-path hosts/macos/Cargo.toml
+
+      - name: Clippy gpui backend
+        run: cargo clippy --locked --manifest-path engine/backends/gpui/Cargo.toml -- -D warnings
+
+      - name: Clippy macos-app host
+        run: cargo clippy --locked --manifest-path hosts/macos/Cargo.toml -- -D warnings
+
+      - name: Build macos-app host
+        run: cargo build --locked --manifest-path hosts/macos/Cargo.toml

.gitignore

@@ -39,3 +39,6 @@ hosts/apple/ns-shell/platforms/
 hosts/apple/ns-shell/hooks/
 hosts/apple/ns-shell/src/assets/pocket/
 hosts/apple/ns-shell/package-lock.json
+
+# tauri codegen (regenerated by tauri-build at compile time)
+tools/bench-desktop/tauri/src-tauri/gen/