Filtered highlights from #664:

• Cargo: epage’s A Vision for Cargo outlines future direction; Cargo also gained profile-debug support, build-started JSON messages with run_id, more trim-paths work, and resolver fixes.
• Compiler: LLVM 23 brought broad compile-time, runtime, bootstrap-time, and artifact-size improvements. Polonius alpha on nightly currently costs about 3% in performance, with mitigation still under investigation.
• Language: There is a call for testing restrictions on trait implementability and field mutability; cyclic trait solving and the next solver are prominent design topics.
• Systems/embedded: Rust Coreutils was covered as a modern rebuild of Unix foundations; a chip-agnostic bare-metal architecture and a universal hardware-in-the-loop HAL test suite are also highlighted.
• Other useful reads: a Rust rewrite performance reality check, TLS benchmark results across four crypto libraries, and git-cache-proxy, a read-only cache for Git clones over slow networks.

The issue also includes literator as crate of the week and RFC approvals for hints.min-opt-level and extern "custom".

Filtered highlights from This Week in Rust 664:

• Rust is soliciting testing for restricting trait implementability and field mutability; the compiler also enabled Polonius on nightly and landed many solver, workspace, and compile-time improvements. LLVM 23 brought broad performance wins, though Polonius currently regresses performance by about 3%.
• Interesting project updates include fearless_simd 0.7 (64-bit integers, improved generics, SSE2, and a path to 1.0), vairedb 0.1 (a cloud-native distributed analytical database), and kache/kobe updates for debuggable restores, convergence, and cluster-lease hardening.
• Strong systems/security reading: formal verification work for BPF, typed conversations that make illegal agent dialogues unrepresentable, TLS handshake benchmarks across four crypto libraries, and a chip-agnostic bare-metal embedded Rust architecture.
• Other notable items: Rust SIMD on GPUs, a reality check on rewriting software in Rust, a universal hardware-in-the-loop HAL test suite, and Rust Coreutils rebuilding Unix foundations.

I skipped the web/UI and general-opinion links; the issue’s most relevant threads are compiler performance, formal verification, distributed systems, embedded Rust, and agent correctness.