docs: add AGENTS.md and CLAUDE.md for Copilot code review (#50)

Adds AGENTS.md (and a CLAUDE.md pointer) so that GitHub Copilot code
review has the repo context it needs to give useful feedback: driver
crate anatomy, WDF patterns, lint configuration, and build/test
commands. Also useful for other AI coding assistants that read these
files.

Author: wmmc88

AGENTS.md

@@ -0,0 +1,182 @@
+# Copilot Instructions
+
+Rust ports of Windows driver samples from the official [Windows Driver Samples](https://github.com/microsoft/Windows-driver-samples), using crates from [windows-drivers-rs](https://github.com/microsoft/windows-drivers-rs). All driver crates target `#![no_std]` and compile as `cdylib` for the Windows kernel.
+
+## Build Commands
+
+Requires EWDK build environment, Clang (LLVM), and `cargo-make`.
+
+```shell
+# Build all workspace members
+cargo build --locked
+
+# Build and package drivers (stamps INF, creates CAT file in Package/)
+cargo make
+
+# Build a specific driver sample
+cargo make --cwd general/echo/kmdf/driver/DriverSync
+
+# Run the echo test app
+cargo run --bin echoapp
+cargo run --bin echoapp -- -Async
+```
+
+## Lint and Formatting
+
+CI enforces all of these — run before submitting PRs:
+
+```shell
+# Clippy (treats warnings as errors)
+cargo clippy --locked --all-targets -- -D warnings
+
+# Clippy with nightly features
+cargo +nightly clippy --locked --all-targets --features nightly -- -D warnings
+
+# Rust formatting (requires nightly due to unstable rustfmt options)
+cargo +nightly fmt --all -- --check
+
+# TOML formatting
+taplo fmt --check --diff
+
+# Unused dependency detection
+cargo machete
+
+# Security audit
+cargo audit --deny warnings
+
+# Documentation build (warnings are errors via RUSTDOCFLAGS=-D warnings in CI)
+cargo doc --locked
+```
+
+## Architecture
+
+### Workspace Layout
+
+- **`general/`** — Functional driver samples (e.g., `echo/kmdf/driver/DriverSync` is a KMDF echo driver)
+- **`tools/`** — Diagnostic/verification drivers (e.g., `dv/kmdf/fail_driver_pool_leak` intentionally leaks memory for Driver Verifier testing)
+- **`general/echo/kmdf/exe`** — User-mode test app (`echoapp`) for the echo driver
+
+### Driver Crate Anatomy
+
+Each driver crate follows this file structure:
+
+- **`lib.rs`** — Crate root with `#![no_std]`, clippy lints, module declarations, context structs, `WDF_*_SIZE` constants, and `wdf_declare_context_type!` macro invocations
+- **`driver.rs`** — `DriverEntry` (exported as `#[export_name = "DriverEntry"]`, `extern "system"`) and `EvtDriverDeviceAdd` callback
+- **`device.rs`** — Device creation, PnP/power callbacks
+- **`queue.rs`** — I/O queue initialization and request handling callbacks
+- **`build.rs`** — Calls `wdk_build::configure_wdk_binary_build()`
+- **`*.inx`** — INF template file for driver installation
+
+### Key Crate Dependencies (from windows-drivers-rs)
+
+| Crate | Purpose |
+|-------|---------|
+| `wdk` | Safe Rust wrappers and macros (`println!`, `paged_code!`, `nt_success`, `wdf::Timer`, `wdf::SpinLock`) |
+| `wdk-sys` | Raw FFI bindings to WDK. Use via `call_unsafe_wdf_function_binding!` macro |
+| `wdk-alloc` | `WdkAllocator` — kernel-compatible global allocator |
+| `wdk-panic` | Kernel-compatible panic handler |
+| `wdk-build` | Build-time configuration for driver compilation and `cargo-make` integration |
+
+## Key Conventions
+
+### Driver Entry Points
+
+- `DriverEntry` must use `#[export_name = "DriverEntry"]` and `extern "system"` calling convention
+- Place init code in `#[link_section = "INIT"]`; place pageable code in `#[link_section = "PAGE"]` and invoke `paged_code!()` at function entry
+- WDF callbacks use `extern "C"` calling convention
+
+### WDF Function Calls
+
+All WDF framework function calls go through the `call_unsafe_wdf_function_binding!` macro from `wdk-sys`. These are always `unsafe` blocks:
+
+```rust
+unsafe {
+    call_unsafe_wdf_function_binding!(
+        WdfDriverCreate,
+        driver as PDRIVER_OBJECT,
+        registry_path,
+        WDF_NO_OBJECT_ATTRIBUTES,
+        &raw mut driver_config,
+        driver_handle_output,
+    )
+}
+```
+
+### WDF Structure Sizes
+
+WDF structs require their `Size` field to be set. Use const-evaluated `WDF_*_SIZE` constants with compile-time truncation assertions:
+
+```rust
+#[allow(
+    clippy::cast_possible_truncation,
+    reason = "size_of::<WDF_DRIVER_CONFIG>() is known to fit in ULONG due to below const assert"
+)]
+const WDF_DRIVER_CONFIG_SIZE: ULONG = {
+    const S: usize = core::mem::size_of::<WDF_DRIVER_CONFIG>();
+    const { assert!(S <= ULONG::MAX as usize) };
+    S as ULONG
+};
+```
+
+### WDF Object Contexts
+
+Context types are registered using macros from `wdf_object_context.rs`:
+
+- `wdf_declare_context_type!(MyContext)` — generates `wdf_object_get_my_context` accessor
+- `wdf_declare_context_type_with_name!(MyContext, custom_getter_name)` — generates a named accessor
+- `wdf_get_context_type_info!(MyContext)` — retrieves the type info pointer for `WDF_OBJECT_ATTRIBUTES.ContextTypeInfo`
+
+### Kernel Allocator and Panic Handler
+
+Every driver crate must include both, gated behind `#[cfg(not(test))]`:
+
+```rust
+#[cfg(not(test))]
+extern crate wdk_panic;
+
+#[cfg(not(test))]
+use wdk_alloc::WdkAllocator;
+
+#[cfg(not(test))]
+#[global_allocator]
+static GLOBAL_ALLOCATOR: WdkAllocator = WdkAllocator;
+```
+
+### Clippy Configuration
+
+All driver crates enable strict clippy lints:
+
+```rust
+#![deny(clippy::all)]
+#![warn(clippy::pedantic)]
+#![warn(clippy::nursery)]
+#![warn(clippy::cargo)]
+#![allow(clippy::missing_safety_doc)]
+```
+
+### Nightly Feature Gating
+
+Crates expose an optional `nightly` feature for unstable Rust capabilities. The feature cascades through `wdk` and `wdk-sys`:
+
+```toml
+[features]
+nightly = ["wdk/nightly", "wdk-sys/nightly"]
+```
+
+### Formatting
+
+- Rust: Uses nightly `rustfmt` with unstable options (see `rustfmt.toml`): `imports_granularity = "Crate"`, `group_imports = "StdExternalCrate"`, `hex_literal_case = "Upper"`, among others
+- TOML: Uses `taplo` with CRLF line endings (`taplo.toml`)
+
+### Rust Flags
+
+`-C target-feature=+crt-static` is set in `.cargo/config.toml` and must also be in CI `RUSTFLAGS`. CI also sets `-D warnings` to deny all warnings.
+
+### Copyright Headers
+
+Every `.rs` file starts with:
+
+```rust
+// Copyright (c) Microsoft Corporation.
+// License: MIT OR Apache-2.0
+```

CLAUDE.md

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+@AGENTS.md