diff --git a/Cargo.toml b/Cargo.toml
index 68dfa8f..210454e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -2,10 +2,12 @@
 name = "wl-webrtc"
 version = "0.1.0"
 edition = "2021"
-# Matches README's "Rust toolchain (1.70+)". Pinning rust-version prevents
-# building on toolchains older than we've actually tested, and gives cargo
-# a useful error message instead of a parse/error cascade.
-rust-version = "1.70"
+# MSRV pinned to 1.87 to match the actual API floor — the codebase uses
+# u32::is_multiple_of (1.87) and Option::is_none_or (1.82) introduced by
+# clippy autofixes. README's Prerequisites section mirrors this. Bumping
+# this floor requires checking clippy::incompatible_msrv against the new
+# value.
+rust-version = "1.87"
 description = "Wayland screen capture and encoding tool"
 
 [dependencies]
diff --git a/README.md b/README.md
index ad7ff81..91d87d1 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,7 @@ Wayland screen capture and encoding tool.
 
 ## Prerequisites
 
-- **Rust toolchain** (1.70+): `rustup default stable`
+- **Rust toolchain** (1.87+; MSRV pinned to match `u32::is_multiple_of` / `Option::is_none_or` usage): `rustup default stable`
 - **FFmpeg 6.0+** dev libraries with VAAPI support:
   - Arch: `pacman -S ffmpeg`
   - Ubuntu/Debian: `apt install libavcodec-dev libavformat-dev libavutil-dev libswscale-dev libva-dev`
diff --git a/src/state_portal.rs b/src/state_portal.rs
index a2678b5..9c6f1ec 100644
--- a/src/state_portal.rs
+++ b/src/state_portal.rs
@@ -1,4 +1,7 @@
 // 采集门户状态模块 —— 通过 PipeWire/DMA-BUF 进行屏幕采集并编码
+// AsRawFd is required by frame.fd.as_raw_fd() in build_drm_descriptor below
+// but rustc emits a false "unused_imports" warning because OwnedFd also has
+// an inherent as_raw_fd — same quirk as avhw.rs. E0599 if removed → keep it.
 use std::os::fd::AsRawFd;
 use std::path::PathBuf;
 use std::sync::atomic::{AtomicBool, Ordering};
diff --git a/src/transform.rs b/src/transform.rs
index c800715..afd3774 100644
--- a/src/transform.rs
+++ b/src/transform.rs
@@ -1,11 +1,11 @@
-/// Coordinate transformation module for Wayland output transforms.
-//
-// Historically exposed a family of `Rect`/`screen_to_frame`/`fit_inside_bounds`
-// helpers for ROI-based capture clipping. Those were never wired into the
-// capture pipeline (we capture full frames and let FFmpeg's filter graph handle
-// any scaling/rotation); they have been removed. Only `Transform` and the
-// `transpose_if_transform_transposed` helper remain — both are actively used by
-// `state.rs` and `avhw.rs`.
+//! Coordinate transformation module for Wayland output transforms.
+//!
+//! Historically exposed a family of `Rect`/`screen_to_frame`/`fit_inside_bounds`
+//! helpers for ROI-based capture clipping. Those were never wired into the
+//! capture pipeline (we capture full frames and let FFmpeg's filter graph handle
+//! any scaling/rotation); they have been removed. Only `Transform` and the
+//! `transpose_if_transform_transposed` helper remain — both are actively used by
+//! `state.rs` and `avhw.rs`.
 
 /// Wayland output transform enum, matching `wl_output::Transform`.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]