Question regarding the output of rust_sitrep()

Dear package authors,

I created this message since I don't understand the output of `rust_sitrep()`. Why does it say that I should use `stable-x86_64-pc-windows-msvc` while the previous line says that I'm already using that toolchain?

``` r
library(rextendr)
rust_sitrep()
#> Rust infrastructure sitrep:
#> ✔ "rustup": 1.28.2 (e4f3ad6f8 2025-04-28)
#> ✔ "cargo": 1.91.1 (ea2d97820 2025-10-10)
#> ℹ host: x86_64-pc-windows-msvc
#> ℹ toolchain: stable-x86_64-pc-windows-msvc (active, default)
#> ! This toolchain should be default: stable-x86_64-pc-windows-msvc (active, default)
#> ℹ Run e.g. `rustup default stable-x86_64-pc-windows-msvc (active, default)`
```

^{Created on 2025-12-07 with [reprex v2.1.1.9000](https://reprex.tidyverse.org)}

Session info

``` r
sessioninfo::session_info()
#> Warning in system2("quarto", "-V", stdout = TRUE, env = paste0("TMPDIR=", :
#> running command '"quarto"
#> TMPDIR=C:/Users/andre/AppData/Local/Temp/Rtmp8YJvgx/file69bc15bd16b9 -V' had
#> status 1
#> ─ Session info ───────────────────────────────────────────────────────────────
#> setting value
#> version R version 4.4.2 (2024-10-31 ucrt)
#> os Windows 11 x64 (build 26200)
#> system x86_64, mingw32
#> ui RTerm
#> language (EN)
#> collate Italian_Italy.utf8
#> ctype Italian_Italy.utf8
#> tz Europe/Rome
#> date 2025-12-07
#> pandoc 3.2 @ C:/Program Files/RStudio/resources/app/bin/quarto/bin/tools/ (via rmarkdown)
#> quarto NA @ C:\\Users\\andre\\AppData\\Local\\Programs\\Quarto\\bin\\quarto.exe
#>
#> ─ Packages ───────────────────────────────────────────────────────────────────
#> package * version date (UTC) lib source
#> cli 3.6.5 2025-04-23 [1] CRAN (R 4.4.2)
#> digest 0.6.37 2024-08-19 [1] CRAN (R 4.4.2)
#> dplyr 1.1.4 2023-11-17 [1] CRAN (R 4.4.2)
#> evaluate 1.0.3 2025-01-10 [1] CRAN (R 4.4.2)
#> fastmap 1.2.0 2024-05-15 [1] CRAN (R 4.4.2)
#> fs 1.6.5 2024-10-30 [1] CRAN (R 4.4.2)
#> generics 0.1.3 2022-07-05 [1] CRAN (R 4.4.2)
#> glue 1.8.0 2024-09-30 [1] CRAN (R 4.4.2)
#> htmltools 0.5.8.1 2024-04-04 [1] CRAN (R 4.4.2)
#> jsonlite 1.8.9 2024-09-20 [1] CRAN (R 4.4.2)
#> knitr 1.50.4 2025-07-11 [1] https://yihui.r-universe.dev (R 4.4.2)
#> lifecycle 1.0.4 2023-11-07 [1] CRAN (R 4.4.2)
#> magrittr 2.0.3 2022-03-30 [1] CRAN (R 4.4.2)
#> pillar 1.10.2 2025-04-05 [1] CRAN (R 4.4.3)
#> pkgconfig 2.0.3 2019-09-22 [1] CRAN (R 4.4.2)
#> processx 3.8.5 2025-01-08 [1] CRAN (R 4.4.2)
#> ps 1.8.1 2024-10-28 [1] CRAN (R 4.4.2)
#> R6 2.6.1 2025-02-15 [1] CRAN (R 4.4.2)
#> reprex 2.1.1.9000 2025-02-25 [1] Github (tidyverse/reprex@07cd5d7)
#> rextendr * 0.4.2.9000 2025-11-16 [1] https://extendr.r-universe.dev (R 4.4.2)
#> rlang 1.1.6 2025-04-11 [1] CRAN (R 4.4.3)
#> rmarkdown 2.29 2024-11-04 [1] CRAN (R 4.4.2)
#> rstudioapi 0.17.1 2024-10-22 [1] CRAN (R 4.4.2)
#> sessioninfo 1.2.3 2025-02-05 [1] CRAN (R 4.4.2)
#> stringi 1.8.7 2025-03-27 [1] CRAN (R 4.4.2)
#> tibble 3.3.0 2025-06-08 [1] CRAN (R 4.4.2)
#> tidyselect 1.2.1 2024-03-11 [1] CRAN (R 4.4.2)
#> vctrs 0.6.5 2023-12-01 [1] CRAN (R 4.4.2)
#> withr 3.0.2 2024-10-28 [1] CRAN (R 4.4.2)
#> xfun 0.52 2025-04-02 [1] CRAN (R 4.4.2)
#> yaml 2.3.10 2024-07-26 [1] CRAN (R 4.4.2)
#>
#> [1] C:/Users/andre/AppData/Local/R/win-library/4.4
#> [2] C:/Program Files/R/R-4.4.2/library
#> * ── Packages attached to the search path.
#>
#> ──────────────────────────────────────────────────────────────────────────────
```

Start with the `rust_sitrep()` entry point and trace how the active, default toolchain is compared with the recommended toolchain. Reproduce the Windows output shown in the issue; done means the diagnostic no longer recommends the already-active default toolchain, with the matching case covered by a test.

Written by the indexing model from the issue text.