initial release (v0.1.0)

Cross-platform, observe-only global keyboard taps with left/right
modifier fidelity and clean shutdown. macOS, Windows, and Linux (evdev).

Backends:
- macOS: CGEventTap on a dedicated CFRunLoop thread, IOHIDCheckAccess
  permission gate, per-instance user_info so multiple Taps coexist,
  FlagsChanged synthesized into KeyDown/KeyUp via CGEventFlags diff.
  Never calls TSM / UCKeyTranslate — avoids the Sonoma main-thread crash
  class entirely.
- Windows: SetWindowsHookExW(WH_KEYBOARD_LL) on a message-pump thread,
  thread_local routing (no globals), PostThreadMessageW(WM_QUIT) drives
  clean Drop, repeat detection synthesized from a held-set, defensive
  left/right disambiguation via scanCode / LLKHF_EXTENDED.
- Linux: evdev via /dev/input/event*; works on X11 and Wayland. Device
  scan filtered by KEY_A probe, non-blocking fd polling, /dev/input
  rescan for USB/Bluetooth hotplug, typed PermissionDenied / NoDevices.

Optional chord-matcher (default 'chord' feature) built on top: set-based
chord definitions, longest-match resolution with first-registered
tie-break, edge-triggered on KeyRepeat, non-overlapping Start/End
transitions. 10 unit tests covering the state machine.

Scancode tables ported from Narsil/rdev (MIT) for all three platforms.
Linux device-scan pattern adapted from martintrojer/hotkey-listener
(MIT).

Verified: cargo check + clippy clean on aarch64-apple-darwin,
aarch64-unknown-linux-gnu, x86_64-pc-windows-gnu. cargo test --lib:
13/13. macOS pipeline live-tested end-to-end.

Author: jamiepine

.github/workflows/ci.yml

@@ -0,0 +1,77 @@
+name: ci
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch:
+
+env:
+  CARGO_TERM_COLOR: always
+  RUSTFLAGS: -Dwarnings
+
+jobs:
+  test:
+    name: test (${{ matrix.os }})
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: clippy, rustfmt
+
+      - uses: Swatinem/rust-cache@v2
+
+      - name: cargo fmt
+        run: cargo fmt --all -- --check
+
+      - name: cargo clippy
+        run: cargo clippy --all-targets --all-features -- -D warnings
+
+      - name: cargo build
+        run: cargo build --all-targets --all-features
+
+      - name: cargo test
+        run: cargo test --lib --all-features
+
+  cross-check:
+    name: cross-check
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        target:
+          - aarch64-apple-darwin
+          - aarch64-unknown-linux-gnu
+          - x86_64-pc-windows-gnu
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: ${{ matrix.target }}
+
+      - uses: Swatinem/rust-cache@v2
+        with:
+          key: ${{ matrix.target }}
+
+      - name: cargo check
+        run: cargo check --target ${{ matrix.target }} --all-features
+
+  msrv:
+    name: msrv (1.85)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: dtolnay/rust-toolchain@1.85.0
+
+      - uses: Swatinem/rust-cache@v2
+
+      - name: cargo build
+        run: cargo build --all-features

.gitignore

@@ -0,0 +1,2 @@
+/target
+/Cargo.lock

Cargo.toml

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+[package]
+name = "keytap"
+version = "0.1.0"
+edition = "2024"
+rust-version = "1.85"
+license = "MIT OR Apache-2.0"
+description = "Cross-platform, observe-only global keyboard taps with left/right modifier fidelity and clean shutdown"
+repository = "https://github.com/jamiepine/keytap"
+keywords = ["keyboard", "hotkey", "global", "input", "evdev"]
+categories = ["os", "hardware-support", "api-bindings"]
+readme = "README.md"
+
+[features]
+default = ["chord"]
+chord = []
+tracing = ["dep:tracing"]
+serde = ["dep:serde"]
+
+[dependencies]
+crossbeam-channel = "0.5"
+thiserror = "2"
+tracing = { version = "0.1", optional = true }
+serde = { version = "1", optional = true, features = ["derive"] }
+
+[target.'cfg(target_os = "macos")'.dependencies]
+objc2 = "0.6"
+objc2-foundation = { version = "0.3", default-features = false, features = ["std", "NSAutoreleasePool"] }
+objc2-core-foundation = { version = "0.3", default-features = false, features = ["std", "CFRunLoop", "CFMachPort"] }
+objc2-core-graphics = { version = "0.3", default-features = false, features = ["std", "CGEvent", "CGEventTypes"] }
+libc = "0.2"
+
+[target.'cfg(target_os = "windows")'.dependencies.windows-sys]
+version = "0.59"
+features = [
+    "Win32_UI_WindowsAndMessaging",
+    "Win32_UI_Input_KeyboardAndMouse",
+    "Win32_Foundation",
+    "Win32_System_Threading",
+    "Win32_System_LibraryLoader",
+]
+
+[target.'cfg(target_os = "linux")'.dependencies]
+evdev = "0.13"
+nix = { version = "0.29", features = ["poll", "event"] }
+
+[dev-dependencies]
+anyhow = "1"