ci: fix NuGet push arguments and stop rebuilding in the publish job

dotnet nuget push is not an MSBuild command and has no --verbosity
option - DotNet.exec's Verbosity setting appended one and the first
9.0.0 publish attempt died on argument parsing before any upload.
Drop it, add --skip-duplicate so re-runs of a failed release are
idempotent, and report the exit code on failure (stderr was empty).

The publish job also re-ran the entire FAKE chain (restore, build,
121 tests x 3 TFMs, pack). It now downloads the nupkg the build job
already produced and tested in the same run and only pushes it
(--single-target skips the dependency chain), so we ship the exact
verified bits.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: mishamyte

.github/workflows/ci.yaml

@@ -102,15 +102,21 @@ jobs:
     timeout-minutes: 15
     steps:
       - uses: actions/checkout@v6
-        with:
-          fetch-depth: 0
 
       - name: Setup .NET
         uses: actions/setup-dotnet@v5.3.0
         with:
           dotnet-version: 10.x
 
-      - name: Pack & Push
-        run: dotnet fsi build.fsx -- --target Push
+      # Push the exact bits the build job produced and tested in this run —
+      # no rebuild, no re-test (--single-target skips the FAKE dependency chain).
+      - name: Download packed artifact
+        uses: actions/download-artifact@v8
+        with:
+          name: nuget-ubuntu-latest
+          path: artifacts
+
+      - name: Push
+        run: dotnet fsi build.fsx -- --target Push --single-target
         env:
           NUGET_API_KEY: ${{ secrets.NUGET_API_KEY }}

build.fsx

@@ -112,17 +112,16 @@ Target.create "Push" (fun _ ->
 
     !! $"{Artifacts}/*.nupkg"
     |> Seq.iter (fun pkg ->
-        let result =
-            DotNet.exec
-                (fun o ->
-                    { o with
-                        Verbosity = Some DotNet.Verbosity.Minimal
-                    })
-                "nuget"
-                $"push \"{pkg}\" -s https://api.nuget.org/v3/index.json -k {key}"
+        // No DotNet.exec Verbosity here: `dotnet nuget push` is not an MSBuild command and
+        // has no --verbosity option — passing one fails argument parsing before any upload.
+        // --skip-duplicate makes re-runs of a (partially) failed release idempotent.
+        let args =
+            $"push \"{pkg}\" -s https://api.nuget.org/v3/index.json -k {key} --skip-duplicate"
+
+        let result = DotNet.exec id "nuget" args
 
         if not result.OK then
-            failwithf $"nuget push failed: %A{result.Errors}"))
+            failwithf $"nuget push failed for %s{pkg} with exit code %d{result.ExitCode}"))
 
 // Run the BenchmarkDotNet suites (V9 + V8 + YetAnother). Standalone — deliberately NOT in
 // the Default chain (slow, and pulls the V8 NuGet closure). Cross-platform via dotnet fsi: