fetchPnpmDeps,pnpmConfigHook: remove dead fetcherVersion < 3 infrastructure

With fetcherVersion = 1 and 2 removed, the minimum supported version is 3,
so every store is a reproducible tarball with consistent permissions. Drop
the now-unreachable `fetcherVersion < 3` branches:

- always bundle the store into pnpm-store.tar.zst (drop the direct-to-$out path)
- always write $out/.fetcher-version (drop the `> 1` guard)
- always normalise permissions (drop the `>= 2` guard)
- always extract the tarball in pnpmConfigHook and serve.nix (drop the cp
  fallback and the `|| echo 1` default)

The `>= 4` SQLite-dump guard is kept, since v3 and v4 still differ. Output
for existing v3/v4 derivations is byte-identical, so no hashes change.

Assisted-by: claude-code with claude-opus-4-7[1m]-xhigh

pkgs/build-support/node/fetch-pnpm-deps/default.nix

@@ -111,15 +111,10 @@ in
               exit 1
             fi
 
-            # For fetcherVersion < 3, the pnpm store files are placed directly into $out.
-            # For fetcherVersion >= 3, it is bundled into a compressed tarball within $out,
+            # The pnpm store is bundled into a compressed tarball within $out,
             # without distributing the uncompressed store files.
-            if [[ ${toString fetcherVersion} -ge 3 ]]; then
-              mkdir $out
-              storePath=$(mktemp -d)
-            else
-              storePath=$out
-            fi
+            mkdir $out
+            storePath=$(mktemp -d)
 
             pushd "$HOME"
             pnpmVersion=$(pnpm --version)
@@ -158,10 +153,8 @@ in
                 --registry="$NIX_NPM_REGISTRY" \
                 --frozen-lockfile
 
-            # Store newer fetcherVersion in case pnpmConfigHook also needs it
-            if [[ ${toString fetcherVersion} -gt 1 ]]; then
-              echo ${toString fetcherVersion} > $out/.fetcher-version
-            fi
+            # Record the fetcherVersion in the output for introspection.
+            echo ${toString fetcherVersion} > $out/.fetcher-version
 
             runHook postInstall
           '';
@@ -201,24 +194,20 @@ in
             # * All folders have 555.
             # See https://github.com/NixOS/nixpkgs/pull/350063
             # See https://github.com/NixOS/nixpkgs/issues/422889
-            if [[ ${toString fetcherVersion} -ge 2 ]]; then
-              find $storePath -type f -name "*-exec" -print0 | xargs --no-run-if-empty -0 chmod 555
-              find $storePath -type f -not -name "*-exec" -print0 | xargs --no-run-if-empty -0 chmod 444
-              find $storePath -type d -print0 | xargs --no-run-if-empty -0 chmod 555
-            fi
+            find $storePath -type f -name "*-exec" -print0 | xargs --no-run-if-empty -0 chmod 555
+            find $storePath -type f -not -name "*-exec" -print0 | xargs --no-run-if-empty -0 chmod 444
+            find $storePath -type d -print0 | xargs --no-run-if-empty -0 chmod 555
 
-            if [[ ${toString fetcherVersion} -ge 3 ]]; then
-              (
-                cd $storePath
+            (
+              cd $storePath
 
-                # Build a reproducible tarball, per instructions at https://reproducible-builds.org/docs/archives/
-                tar --sort=name \
-                  --mtime="@$SOURCE_DATE_EPOCH" \
-                  --owner=0 --group=0 --numeric-owner \
-                  --pax-option=exthdr.name=%d/PaxHeaders/%f,delete=atime,delete=ctime \
-                  --zstd -cf $out/pnpm-store.tar.zst .
-              )
-            fi
+              # Build a reproducible tarball, per instructions at https://reproducible-builds.org/docs/archives/
+              tar --sort=name \
+                --mtime="@$SOURCE_DATE_EPOCH" \
+                --owner=0 --group=0 --numeric-owner \
+                --pax-option=exthdr.name=%d/PaxHeaders/%f,delete=atime,delete=ctime \
+                --zstd -cf $out/pnpm-store.tar.zst .
+            )
 
             runHook postFixup
           '';

pkgs/build-support/node/fetch-pnpm-deps/pnpm-config-hook.sh

@@ -40,7 +40,7 @@ pnpmConfigHook() {
 
     echo "Found 'pnpm' with version '$pnpmVersion'"
 
-    fetcherVersion=$(cat "${pnpmDeps}/.fetcher-version" || echo 1)
+    fetcherVersion=$(cat "${pnpmDeps}/.fetcher-version")
 
     echo "Using fetcherVersion: $fetcherVersion"
 
@@ -52,11 +52,7 @@ pnpmConfigHook() {
     export npm_config_platform="@npmPlatform@"
     export pnpm_config_platform="@npmPlatform@"
 
-    if [[ $fetcherVersion -ge 3 ]]; then
-      tar --zstd -xf "$pnpmDeps/pnpm-store.tar.zst" -C "$STORE_PATH"
-    else
-      cp -Tr "$pnpmDeps" "$STORE_PATH"
-    fi
+    tar --zstd -xf "$pnpmDeps/pnpm-store.tar.zst" -C "$STORE_PATH"
 
     chmod -R +w "$STORE_PATH"
 

pkgs/build-support/node/fetch-pnpm-deps/serve.nix

@@ -17,8 +17,6 @@ writeShellApplication {
   text = ''
     storePath=$(mktemp -d)
 
-    fetcherVersion=$(cat "${pnpmDeps}/.fetcher-version" || echo 1)
-
     clean() {
       echo "Cleaning up temporary store at '$storePath'..."
 
@@ -27,11 +25,7 @@ writeShellApplication {
 
     echo "Copying pnpm store '${pnpmDeps}' to temporary store..."
 
-    if [[ $fetcherVersion -ge 3 ]]; then
-      tar --zstd -xf "${pnpmDeps}/pnpm-store.tar.zst" -C "$storePath"
-    else
-      cp -Tr "${pnpmDeps}" "$storePath"
-    fi
+    tar --zstd -xf "${pnpmDeps}/pnpm-store.tar.zst" -C "$storePath"
 
     chmod -R +w "$storePath"