fix(query): keep pacman.conf repo order for exact name matches (#2987)

Motivation
With separatesources enabled (the default), a package with the exact
searched name that exists in several sync repos can be listed in the
wrong order. For example, if [cachyos-extra-v3] comes before [extra] in
pacman.conf, extra/chromium can still show up as the top pick instead of
cachyos-extra-v3/chromium. pacman prefers the repo listed first.

separateSourceScore returned a flat 50 for every exact match, whatever
its source. As a result, all exact matches got the same metric
(50 + 1.0). The unstable slices.SortFunc then left their relative order
unspecified, so the ordering added for non-exact results did not apply
to exact ones.

Approach
Move the repo-order scoring into a repoOrderScore helper (same logic and
cache as before). For exact matches, add repoOrderScore/separateSourceMax
to the 50: a bonus between 0 and 1. Exact matches still outrank every
non-exact result (which scores at most 45 + a metric below 1). Among
exact matches, repos earlier in pacman.conf now come first. Exact AUR
matches keep 50, so an exact sync-repo match now ranks strictly above an
exact AUR match instead of tying with it. Scoring for non-exact results
is unchanged, and nothing changes when separatesources is disabled.

Validation
- go test -race ./pkg/query/... -count=1: passes.
- New tests TestSourceQueryBuilderExactMatchSortsByRepoOrder (top-down
  and bottom-up) and TestSeparateSourceScore_ExactMatchKeepsRepoOrder
  fail with the previous metric.go and pass with this change.
- golangci-lint run ./pkg/query/...: 0 issues; gofmt clean.
- go test ./... on macOS has failures that also occur on the unchanged
  base: Linux-only syscall fields in pkg/settings/exe, and a
  timezone-dependent test in pkg/text. Not tested against a real
  pacman setup with custom repos.

Report: https://github.com/Jguer/yay/issues/2986

Assisted-by: claude-opus-5-5 (via Claude Code)

Signed-off-by: Pujitha Paladugu <10557236+pujitha24@users.noreply.github.com>
Co-authored-by: Pujitha Paladugu <10557236+pujitha24@users.noreply.github.com>

pkg/query/metric.go

@@ -57,10 +57,21 @@ func (a *abstractResults) separateSourceScore(source string, score float64) floa
 		return 0
 	}
 
+	sourceScore := a.repoOrderScore(source)
+
+	// Exact matches always rank above everything else; among them, keep
+	// pacman.conf repo order by adding a bonus in [0, 1].
 	if score == 1.0 {
-		return 50
+		return 50 + sourceScore/separateSourceMax
 	}
 
+	return sourceScore
+}
+
+// repoOrderScore scores sync repositories based on pacman.conf order (as reflected by dbExecutor.Repos()).
+// First repo gets max, last repo gets min, evenly distributed across the range.
+// AUR and unknown sources get 0.
+func (a *abstractResults) repoOrderScore(source string) float64 {
 	if v, ok := a.separateSourceCache[source]; ok {
 		return v
 	}
@@ -70,8 +81,6 @@ func (a *abstractResults) separateSourceScore(source string, score float64) floa
 		return 0
 	}
 
-	// Score sync repositories based on pacman.conf order (as reflected by dbExecutor.Repos()).
-	// First repo gets max, last repo gets min, evenly distributed across the range.
 	for i, repo := range a.repoOrder {
 		if repo != source {
 			continue

pkg/query/metric_test.go

@@ -43,3 +43,23 @@ func TestSeparateSourceScore_UsesRepoOrderEvenlyDistributed(t *testing.T) {
 		assert.Equal(t, 0.0, a.separateSourceScore("aur", sim))
 	})
 }
+
+func TestSeparateSourceScore_ExactMatchKeepsRepoOrder(t *testing.T) {
+	t.Parallel()
+
+	a := &abstractResults{
+		separateSources:     true,
+		repoOrder:           []string{"cachyos-extra-v3", "core", "extra"},
+		separateSourceCache: map[string]float64{},
+	}
+
+	custom := a.separateSourceScore("cachyos-extra-v3", 1.0)
+	extra := a.separateSourceScore("extra", 1.0)
+	aurScore := a.separateSourceScore("aur", 1.0)
+
+	assert.Greater(t, custom, extra)
+	assert.Greater(t, extra, aurScore)
+	assert.Equal(t, 50.0, aurScore)
+	// Exact matches must still outrank any non-exact match.
+	assert.Greater(t, extra+1.0, a.separateSourceScore("cachyos-extra-v3", 0.99)+0.99)
+}

pkg/query/query_builder_test.go

@@ -445,6 +445,83 @@ func TestSourceQueryBuilderTieSortsByRepoOrder(t *testing.T) {
 	}
 }
 
+func TestSourceQueryBuilderExactMatchSortsByRepoOrder(t *testing.T) {
+	t.Parallel()
+
+	testCases := []struct {
+		desc        string
+		bottomUp    bool
+		repoOrder   []string
+		dbOrder     []string
+		wantSources []string
+	}{
+		{
+			desc:        "topdown custom repo first",
+			repoOrder:   []string{"cachyos-extra-v3", "core", "extra"},
+			dbOrder:     []string{"extra", "cachyos-extra-v3"},
+			wantSources: []string{"cachyos-extra-v3", "extra", "aur"},
+		},
+		{
+			desc:        "topdown extra first",
+			repoOrder:   []string{"core", "extra", "cachyos-extra-v3"},
+			dbOrder:     []string{"cachyos-extra-v3", "extra"},
+			wantSources: []string{"extra", "cachyos-extra-v3", "aur"},
+		},
+		{
+			desc:        "bottomup custom repo first",
+			bottomUp:    true,
+			repoOrder:   []string{"cachyos-extra-v3", "core", "extra"},
+			dbOrder:     []string{"extra", "cachyos-extra-v3"},
+			wantSources: []string{"aur", "extra", "cachyos-extra-v3"},
+		},
+	}
+
+	mockAUR := &mockaur.MockAUR{
+		GetFn: func(ctx context.Context, query *aur.Query) ([]aur.Pkg, error) {
+			return []aur.Pkg{{Name: "chromium", PackageBase: "chromium", Version: "1-1"}}, nil
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.desc, func(t *testing.T) {
+			t.Parallel()
+
+			mockDB := &mock.DBExecutor{
+				ReposFn: func() []string { return tc.repoOrder },
+				SyncPackagesFn: func(pkgs ...string) []mock.IPackage {
+					res := make([]mock.IPackage, 0, len(tc.dbOrder))
+					for _, dbName := range tc.dbOrder {
+						res = append(res, &mock.Package{
+							PBase:         "chromium",
+							PName:         "chromium",
+							PVersion:      "153.0.8010.52-1",
+							PDescription:  "A web browser built for speed, simplicity, and security",
+							PDB:           mock.NewDB(dbName),
+							PArchitecture: "x86_64",
+						})
+					}
+					return res
+				},
+				LocalPackageFn: func(string) mock.IPackage { return nil },
+			}
+
+			queryBuilder := NewSourceQueryBuilder(mockAUR,
+				text.NewLogger(io.Discard, io.Discard, strings.NewReader(""), false, "test"),
+				"", parser.ModeAny, "", tc.bottomUp,
+				false, true)
+
+			queryBuilder.Execute(t.Context(), mockDB, []string{"chromium"})
+
+			gotSources := make([]string, len(queryBuilder.results))
+			for i, result := range queryBuilder.results {
+				gotSources[i] = result.source
+			}
+
+			assert.Equal(t, tc.wantSources, gotSources)
+		})
+	}
+}
+
 func TestSourceQueryBuilderTieDoesNotSeparateSources(t *testing.T) {
 	t.Parallel()