feat(conflict): Add Tango request and signature intersection

submitqueue/extension/conflict/tango/BUILD.bazel

@@ -4,25 +4,34 @@ go_library(
     name = "go_default_library",
     srcs = [
         "cache.go",
+        "intersect.go",
+        "mock_request.go",
         "mock_store.go",
+        "request.go",
         "signature.go",
         "store.go",
         "target_label.go",
         "target_signature.go",
     ],
     importpath = "github.com/uber/submitqueue/submitqueue/extension/conflict/tango",
     visibility = ["//visibility:public"],
-    deps = ["@org_uber_go_mock//gomock:go_default_library"],
+    deps = [
+        "//platform/base/change:go_default_library",
+        "@org_uber_go_mock//gomock:go_default_library",
+    ],
 )
 
 go_test(
     name = "go_default_test",
     srcs = [
         "cache_test.go",
+        "intersect_test.go",
+        "request_test.go",
         "signature_test.go",
     ],
     embed = [":go_default_library"],
     deps = [
+        "//platform/base/change:go_default_library",
         "@com_github_stretchr_testify//assert:go_default_library",
         "@com_github_stretchr_testify//require:go_default_library",
     ],

submitqueue/extension/conflict/tango/intersect.go

@@ -0,0 +1,32 @@
+// Copyright (c) 2026 Uber Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package tango
+
+// sharesTarget reports whether two signatures have a target ID in common. Both
+// must be sorted ascending by ID, so the check is one pass over each.
+func sharesTarget(a, b []SignatureTarget) bool {
+	i, j := 0, 0
+	for i < len(a) && j < len(b) {
+		switch {
+		case a[i].ID < b[j].ID:
+			i++
+		case a[i].ID > b[j].ID:
+			j++
+		default:
+			return true
+		}
+	}
+	return false
+}

submitqueue/extension/conflict/tango/intersect_test.go

@@ -0,0 +1,61 @@
+// Copyright (c) 2026 Uber Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package tango
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func targetsWithIDs(ids ...uint64) []SignatureTarget {
+	targets := make([]SignatureTarget, len(ids))
+	for i, id := range ids {
+		targets[i] = SignatureTarget{ID: id}
+	}
+	return targets
+}
+
+func TestSharesTarget(t *testing.T) {
+	const highBit = uint64(1) << 63
+
+	tests := []struct {
+		name string
+		a, b []SignatureTarget
+		want bool
+	}{
+		{name: "both empty"},
+		{name: "one empty", a: targetsWithIDs(1, 2)},
+		{name: "disjoint", a: targetsWithIDs(1, 3, 5), b: targetsWithIDs(2, 4, 6)},
+		{name: "same first ID", a: targetsWithIDs(1, 3), b: targetsWithIDs(1, 9), want: true},
+		{name: "same last ID", a: targetsWithIDs(1, 7), b: targetsWithIDs(2, 7), want: true},
+		{name: "same middle ID", a: targetsWithIDs(1, 4, 9), b: targetsWithIDs(2, 4, 8), want: true},
+		{name: "different lengths", a: targetsWithIDs(5), b: targetsWithIDs(1, 2, 3, 4, 5, 6), want: true},
+		{name: "IDs above the signed range order as unsigned", a: targetsWithIDs(1, highBit), b: targetsWithIDs(2, highBit+1)},
+		{name: "same ID above the signed range", a: targetsWithIDs(1, highBit), b: targetsWithIDs(highBit), want: true},
+		{
+			name: "distance does not affect the result",
+			a:    []SignatureTarget{{ID: 4, Distance: 0}},
+			b:    []SignatureTarget{{ID: 4, Distance: 9}},
+			want: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.want, sharesTarget(tt.a, tt.b))
+			assert.Equal(t, tt.want, sharesTarget(tt.b, tt.a))
+		})
+	}
+}

submitqueue/extension/conflict/tango/request.go

@@ -0,0 +1,53 @@
+// Copyright (c) 2026 Uber Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package tango
+
+//go:generate mockgen -source=request.go -destination=mock_request.go -package=tango
+
+import (
+	"context"
+
+	"github.com/uber/submitqueue/platform/base/change"
+)
+
+// ChangedTargetsRequest asks which targets change when ChangeURIs are applied
+// on top of a base revision.
+type ChangedTargetsRequest struct {
+	// BaseRevision is the full commit SHA the changes are applied on top of.
+	BaseRevision string
+
+	// ChangeURIs lists every change to apply, in batch order.
+	ChangeURIs []string
+}
+
+// ChangedTargetsClient returns the targets a request affects. An adapter owns
+// the Tango client and its stream, collects the response, and resolves each
+// target's label; any failure to produce a complete answer is an error. It also
+// owns the Tango repository remote and computation strategy, which the request
+// does not carry. ChangeURIs are passed through as given, so a URI scheme Tango
+// does not support is an error.
+type ChangedTargetsClient interface {
+	// ChangedTargets returns the affected targets in no particular order, and a
+	// label may repeat. An empty result is valid and means nothing is affected.
+	ChangedTargets(ctx context.Context, request ChangedTargetsRequest) ([]LabelDistance, error)
+}
+
+func changedTargetsRequestFor(baseRevision string, changes []change.Change) ChangedTargetsRequest {
+	var uris []string
+	for _, c := range changes {
+		uris = append(uris, c.URIs...)
+	}
+	return ChangedTargetsRequest{BaseRevision: baseRevision, ChangeURIs: uris}
+}

submitqueue/extension/conflict/tango/request_test.go

@@ -0,0 +1,51 @@
+// Copyright (c) 2026 Uber Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package tango
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/uber/submitqueue/platform/base/change"
+)
+
+func TestChangedTargetsRequestFor(t *testing.T) {
+	baseRevision := "9f2c1d0e3a4b5c6d7e8f9a0b1c2d3e4f5a6b7c8d"
+
+	tests := []struct {
+		name    string
+		changes []change.Change
+		want    []string
+	}{
+		{name: "no changes", want: nil},
+		{name: "one change", changes: []change.Change{{URIs: []string{"a"}}}, want: []string{"a"}},
+		{
+			name:    "URIs are flattened in batch order",
+			changes: []change.Change{{URIs: []string{"a", "b"}}, {URIs: []string{"c"}}, {URIs: []string{"d", "e"}}},
+			want:    []string{"a", "b", "c", "d", "e"},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := changedTargetsRequestFor(baseRevision, tt.changes)
+
+			assert.Equal(t, ChangedTargetsRequest{
+				BaseRevision: baseRevision,
+				ChangeURIs:   tt.want,
+			}, got)
+		})
+	}
+}