diff --git a/pkgs/by-name/bu/buck2/hashes.json b/pkgs/by-name/bu/buck2/hashes.json
index cbf18a92f293..eeb3a0fadcef 100644
--- a/pkgs/by-name/bu/buck2/hashes.json
+++ b/pkgs/by-name/bu/buck2/hashes.json
@@ -1,17 +1,20 @@
 {
   "aarch64-darwin": {
-    "buck2": "sha256-CIysxyxAD6Q4vkBSw2eC9Wsq+GKHqt8T7OXpdy1yRVw=",
-    "rust-project": "sha256-o5m58wQ9zKkpa5GzgLpcLUV9LpA+n+MxVa/9hH9Tr40="
+    "buck2": "sha256-zol0Uh3MnXg5KUO0+QvBpBYN0t8ylHFl64lRVtgwPxc=",
+    "rust-project": "sha256-3x0wqA5K/30ITQO3Xl3NZW5HnQG9yOBFQr0xI0UGbJo=",
+    "starlark_fmt": "sha256-guJ2EGyaP6WLNSaW9fUPYNM5xU3Ge2AzAM3xAGvrdGI="
   },
   "aarch64-linux": {
-    "buck2": "sha256-4jm/cvQKeYfbkCTrbV4yVkL2SWxYnexr5UwQCNJhihk=",
-    "rust-project": "sha256-vGSOwVETwYqwBhkxlSTDJlVcMfbAIzYwDhEKbqz+6ok="
+    "buck2": "sha256-g/HrVfXV3zt7BstOfoZAB9ZArhbxqGq1HpvQKmubck8=",
+    "rust-project": "sha256-vOt/uCO3S5hbXhdq0S7uvKNiszSiTkWMh/hM5CkcOwI=",
+    "starlark_fmt": "sha256-GKsyygMfsGWdBLGv46pyRBeCq3CKqjL5Vi6F+sR1GAY="
   },
   "x86_64-linux": {
-    "buck2": "sha256-7MPYB90LD+/xpCNoi9WYJjuDOdIj5oVXiocZZFbBnZU=",
-    "rust-project": "sha256-de0SbH6cbjdDhcPpDTjxBo5HgQ8yS1eokQYjQrHKIDY="
+    "buck2": "sha256-qjBNRxp59pIzsJdn1Lqa3XaQSbejf3ijpxpymDNy9RE=",
+    "rust-project": "sha256-Nr0agbScDlppNlUrJ+YVxTbXBmRlLdzC2f9AYUR2pEs=",
+    "starlark_fmt": "sha256-W7LjUgUhCTlMtiFz9ExmtkWw0hSOUzZKwAF3np9+Qu4="
   },
-  "version": "2026-07-15",
-  "preludeGit": "caed0b8c0ee137c4e5e1f800a5054df151f490c2",
-  "preludeFod": "sha256-nMHnBf4vQJIxPgarmLPY38b15DFW2FlAQxDCzJgB+w8="
+  "version": "2026-08-01",
+  "preludeGit": "be471f9dd31a45b6c9c1610b1d996455b413b1f6",
+  "preludeFod": "sha256-EqbOUT67jJDx51euhGFWOrLTrZ416Y/ODILsKr5omxE="
 }
diff --git a/pkgs/by-name/bu/buck2/package.nix b/pkgs/by-name/bu/buck2/package.nix
index 15f8fe17c24e..b0b2f8d12e15 100644
--- a/pkgs/by-name/bu/buck2/package.nix
+++ b/pkgs/by-name/bu/buck2/package.nix
@@ -52,25 +52,27 @@ let
       aarch64-linux = "aarch64-unknown-linux-gnu";
     }
     .${stdenv.hostPlatform.system};
+
+  binaries = [
+    # the main Buck2 binary
+    "buck2"
+    # provides IDE integration for Buck2 Rust projects
+    "rust-project"
+    # opinionated formatter for Starlark/BUCK files
+    "starlark_fmt"
+  ];
 in
 stdenv.mkDerivation (finalAttrs: {
   pname = "buck2";
   version = buildHashes.version;
 
-  srcs = [
-    # the platform-specific binary — which is also
-    # zstd-compressed
-    (fetchurl {
-      url = "https://github.com/facebook/buck2/releases/download/${finalAttrs.version}/buck2-${platform-suffix}.zst";
-      hash = archHashes.buck2;
-    })
-    # rust-project, which is used to provide IDE integration Buck2 Rust projects,
-    # is part of the official distribution
-    (fetchurl {
-      url = "https://github.com/facebook/buck2/releases/download/${finalAttrs.version}/rust-project-${platform-suffix}.zst";
-      hash = archHashes.rust-project;
-    })
-  ];
+  srcs = map (
+    binary:
+    fetchurl {
+      url = "https://github.com/facebook/buck2/releases/download/${finalAttrs.version}/${binary}-${platform-suffix}.zst";
+      hash = archHashes.${binary};
+    }
+  ) binaries;
 
   unpackCmd = "unzstd $curSrc -o $(stripHash $curSrc)";
   sourceRoot = ".";
@@ -85,15 +87,14 @@ stdenv.mkDerivation (finalAttrs: {
   ];
 
   buildInputs = [
-    #225963
+    # https://github.com/NixOS/nixpkgs/issues/225963
     stdenv.cc.cc.libgcc or null
   ];
 
   installPhase = ''
     runHook preInstall
 
-    install -D buck2* "$out/bin/buck2"
-    install -D rust-project* "$out/bin/rust-project"
+    ${lib.concatMapStringsSep "\n" (binary: "install -D ${binary}* $out/bin/${binary}") binaries}
 
     runHook postInstall
   '';
diff --git a/pkgs/by-name/bu/buck2/update.nu b/pkgs/by-name/bu/buck2/update.nu
index 57188e797bee..69993a127019 100755
--- a/pkgs/by-name/bu/buck2/update.nu
+++ b/pkgs/by-name/bu/buck2/update.nu
@@ -8,6 +8,7 @@ const ARCHES = [
   { name: "aarch64-linux", target: "aarch64-unknown-linux-gnu" },
   { name: "aarch64-darwin", target: "aarch64-apple-darwin" },
 ];
+const BINARIES = ["buck2", "rust-project", "starlark_fmt"]
 
 const MANIFEST = "pkgs/by-name/bu/buck2/hashes.json"
 
@@ -19,30 +20,31 @@ def main [] {
     | get name
 
   let preludeHash = http get $"https://github.com/facebook/buck2/releases/download/($version)/prelude_hash" | decode | str trim
-  let preludeFod = run-external "nix" "--extra-experimental-features" "nix-command" "store" "prefetch-file" "--json" $"https://github.com/facebook/buck2-prelude/archive/($preludeHash).tar.gz" | from json | get hash
+  let preludeFod = prefetch-hash $"https://github.com/facebook/buck2-prelude/archive/($preludeHash).tar.gz"
 
   print $"Newest version: ($version)"
   print $"Newest prelude hash: ($preludeHash)"
 
-  let hashes = $ARCHES | par-each {
-    |arch|
-
-    {
-      $arch.name: {
-        "buck2": (run-external "nix" "--extra-experimental-features" "nix-command" "store" "prefetch-file" "--json" $"https://github.com/facebook/buck2/releases/download/($version)/buck2-($arch.target).zst" | from json | get hash),
-        "rust-project": (run-external "nix" "--extra-experimental-features" "nix-command" "store" "prefetch-file" "--json" $"https://github.com/facebook/buck2/releases/download/($version)/rust-project-($arch.target).zst" | from json | get hash),
+  let json = $ARCHES
+    | par-each { |arch|
+      {
+        $arch.name: (
+          $BINARIES | each { |binary|
+            { $binary: (prefetch-hash $"https://github.com/facebook/buck2/releases/download/($version)/($binary)-($arch.target).zst") }
+          } | into record
+        )
       }
     }
-  } | reduce { |val, accum| $accum | merge $val }
-
-  let new_manifest = $hashes
+    | into record
+    | sort # keep diffs minimal
     | insert "version" $version
     | insert "preludeGit" $preludeHash
     | insert "preludeFod" $preludeFod
+    | to json
 
-  $new_manifest
-  | to json
-  | append "\n"
-  | str join
-  | save -f $MANIFEST
+  $json + "\n" | save -f $MANIFEST
+}
+
+def prefetch-hash [url: string]: nothing -> string {
+  nix --extra-experimental-features nix-command store prefetch-file --json $url | from json | get hash
 }