test: normalize paths in TestDiscoverIntegration for cross-OS matrix

The diagnose-test-failure job uploaded test artifacts and showed the
exact failure on both macOS and Windows is the same:

  macOS:   Root() = "/private/var/folders/.../001"
           want    "/var/folders/.../001"
  Windows: Root() = "C:/Users/runneradmin/AppData/Local/Temp/.../001"
           want    "C:\\Users\\RUNNER~1\\AppData\\Local\\Temp\\...\\001"

`git rev-parse --show-toplevel` (which Discover() returns verbatim):

- Resolves symlinks on macOS — /var → /private/var
- Returns forward slashes on Windows where Go's filepath uses backslash
- Returns the Windows long-path form (runneradmin) where t.TempDir()
  may return the 8.3 short form (RUNNER~1)

These are real OS differences exposed by the new cross-OS test matrix,
not bugs in Discover() itself. Fix the comparison in the test by piping
both sides through filepath.FromSlash + filepath.EvalSymlinks before
the equality check.

Also drop the temporary diagnose-test-failure job — its purpose was to
surface this failure once, and it's no longer needed.

https://claude.ai/code/session_01Sy9fRJ7oL6ghGxJAVvEPLW

Author: claude

.github/workflows/ci.yml

@@ -95,52 +95,6 @@ jobs:
           path: coverage.out
           if-no-files-found: error
 
-  # Temporary diagnostic job: when the test matrix fails, download every test
-  # output artifact and post the tail of each as a PR comment. Actions logs
-  # are gated behind authentication so this is currently the most reliable way
-  # to surface OS-specific failures. Remove once the matrix is consistently
-  # green.
-  diagnose-test-failure:
-    if: failure() && github.event_name == 'pull_request'
-    needs: test
-    runs-on: ubuntu-latest
-    timeout-minutes: 5
-
-    permissions:
-      contents: read
-      pull-requests: write
-
-    steps:
-      - uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4.3.0
-        with:
-          path: ./diag
-          pattern: test-output-*
-
-      - name: Post test output as PR comment
-        env:
-          GH_TOKEN: ${{ github.token }}
-          GH_REPO: ${{ github.repository }}
-          PR_NUMBER: ${{ github.event.pull_request.number }}
-        shell: bash
-        run: |
-          set -euo pipefail
-          {
-            echo "## Test failure diagnostics ($(date -u +%Y-%m-%dT%H:%M:%SZ))"
-            echo
-            echo "Auto-generated from ci run \`${GITHUB_RUN_ID}\` on commit \`${GITHUB_SHA::7}\`."
-            for d in diag/test-output-*; do
-              os="${d#diag/test-output-}"
-              echo
-              echo "<details><summary>$os (last 200 lines)</summary>"
-              echo
-              echo '```'
-              tail -200 "$d/test-output.txt"
-              echo '```'
-              echo "</details>"
-            done
-          } > comment.md
-          gh pr comment "$PR_NUMBER" --body-file comment.md
-
   vuln:
     runs-on: ubuntu-latest
     timeout-minutes: 5

internal/git/git_test.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"os"
 	"os/exec"
+	"path/filepath"
 	"strings"
 	"testing"
 	"time"
@@ -603,8 +604,22 @@ func TestDiscoverIntegration(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Discover() error = %v", err)
 	}
-	if repo.Root() != tempDir {
-		t.Fatalf("Root() = %q, want %q", repo.Root(), tempDir)
+	// `git rev-parse --show-toplevel` returns a path that has been resolved
+	// for symlinks (macOS: /var → /private/var) and that uses forward slashes
+	// regardless of OS (Windows: C:/Users/... vs Go's native C:\Users\...).
+	// Normalize both sides through filepath.FromSlash + EvalSymlinks so the
+	// comparison is OS-agnostic — also resolves Windows 8.3 short names like
+	// RUNNER~1 to their long form.
+	got, err := filepath.EvalSymlinks(filepath.FromSlash(repo.Root()))
+	if err != nil {
+		t.Fatalf("EvalSymlinks(Root()=%q) error = %v", repo.Root(), err)
+	}
+	want, err := filepath.EvalSymlinks(filepath.FromSlash(tempDir))
+	if err != nil {
+		t.Fatalf("EvalSymlinks(tempDir=%q) error = %v", tempDir, err)
+	}
+	if got != want {
+		t.Fatalf("Root() = %q (normalized %q), want %q (normalized %q)", repo.Root(), got, tempDir, want)
 	}
 
 	if err := repo.SetConfigBool("gitreal.enabled", true); err != nil {