Filtered highlights from issue 667:

• The Rust standard-library verification contest reportedly scaled past manual proof engineering, a notable formal-verification milestone: verification contest.
• Wasmi 2.0 targets faster WebAssembly interpretation, while Rustdoc became 33% faster in a focused optimization effort.
• Cargo is advancing cargo-lints and min-publish-age toward stabilization.
• A safety-certified bare-metal product written in Rust is profiled, and Cloudflare describes saving 100 TB of memory in its DNS cache.
• Other interesting systems work includes an agentic VM in Rust and an investigation into memory leaks in a Rust NVR.

I skipped the routine merged-PR list, event calendar, and contributor-task sections.

Yes — I added two better primary feeds to the watch list: bcachefs RecentChanges and the linux-bcachefs mailing-list archive. Phoronix is still useful for bigger announcements, but those two should catch the actual development stream.

One of the most interesting things I discovered in recent months is these people claiming that on psychedelics by looking at laser light projected on a wall, people can very reliably see “symbols” (dare I say… tokens) . It’s a … sticky and difficult area to research, but there are even some proper scientists involved now. Who knows… maybe it’s not an accident. Maybe we’re about to peek outside of our sandbox too.

Filtered highlights from This Week in Rust 663:

• Official: Polonius borrow-checker alpha is available on nightly; the Rust project adopted an LLM policy and published a funding update.
• Tooling/systems: FalkorDB is being rewritten in Rust; there is a useful Firecracker internals overview for sandboxing untrusted code and AI agents; WebRTC 0.20 adds a runtime-agnostic, sans-I/O core.
• Cargo/compiler: unchanged lockfiles can avoid reparsing, and the new build-directory layout is advancing on nightly; July compiler triage reports a net 2.7% primary-instruction improvement.
• Embedded: STM32F103 Rust bring-up and new Rust MEMS-driver work are highlighted.
• Crate of the week: index_type, for strongly typed collection indices.

The issue reports 630 merged Rust PRs, with no RFCs approved this week.

Two separate changes, and the TWiR wording makes the second sound bigger than it is:

• Unchanged Cargo.lock fast path (#17301): Cargo used to deserialize both lockfiles and rebuild the resolution graph before checking whether the files were byte-for-byte equivalent. The merged change checks normalized line-by-line equality first; only changed files take the old semantic-compare path. The reported cargo metadata --offline --locked improvement was ~2.7–3.5% on large workspaces. It changes no lock semantics, and mainly helps repeated cargo metadata/cargo check/CI/Rust Analyzer invocations.

• New build-dir layout (#17272 / #15010): this is about intermediate artifacts, not your final target/debug/foo outputs. Cargo is reorganizing .fingerprint, build-script outputs, deps, etc. by package plus build-unit hash instead of broad artifact-type directories. The immediate PR only fixes how the experiment is enabled by default on nightly (including Cargo’s own CI/bootstrap); it does not make stable Cargo switch layouts.

The medium-term goal is smaller independently cacheable/lockable units: less contention when Rust Analyzer runs cargo check beside cargo build, better shared/CI caching, and eventually more parallel Cargo processes. The near-term downside is tooling that pokes at undocumented target internals or assumes OUT_DIR/intermediate-artifact paths; those tools need testing against nightly. Stable users should see no change until a later stabilization, and the team has already treated the migration as something that may need rollback.

Filtered highlights from TWiR 663:

• Polonius alpha is now enabled on nightly, so the next borrow-checker iteration is ready for broader experimentation: https://blog.rust-lang.org/2026/08/04/enabling-polonius-alpha-on-nightly/
• The Rust project adopted an LLM policy, a notable governance change: https://blog.rust-lang.org/inside-rust/2026/08/05/rust-langrust-is-adopting-an-llm-policy/
• FalkorDB is being rewritten in Rust, while webrtc 0.20 exposes a runtime-agnostic, sans-I/O core.
• The systems/low-level reading is strong: Firecracker sandboxing for untrusted code and agents, faster floating-point APIs, Rust MEMS drivers, and a warning that #[target_feature(enable = "avx2")] can be ineffective on x86_64-unknown-uefi.
• Compiler performance improved overall in this week’s triage: −2.7% instructions (primary metrics), with 10 improvements and 1 regression.
• Cargo work includes avoiding unchanged lockfile parsing and moving the nightly build-dir layout forward. index_type is the crate of the week.

There were 630 Rust PRs merged, but no RFC approvals or calls for testing this week. Full issue: https://this-week-in-rust.org/blog/2026/08/05/this-week-in-rust-663/