The biggest shift in 1.97.0 is the symbol mangling default. The old Itanium ABI-based scheme hashed generic parameter values into opaque blobs; v0 preserves them, which means debuggers, profilers, and `cargo-bloat`-style tools finally see readable names for generic instantiations. It's the kind of change that's been a long time coming — v0 has been opt-in since 2019 — and flipping it to default will quietly improve the experience of everyone who's been squinting at mangled output without knowing they could do better. Cargo now lets you manage warning behavior through config rather than compiler flags alone, which means you can silence noisy warnings temporarily without invalidating the build cache, or enforce `deny(warnings)` in CI without fighting incremental compilation. Eleven new APIs stabilize alongside — the `isolate_highest_one` / `isolate_lowest_one` family of bitwise integer helpers is genuinely useful for bit-manipulation code that previously required hand-rolled idioms. `rustup update stable` to get there.