feat(conflict): Add target signature and dictionary store contracts

submitqueue/extension/conflict/tango/BUILD.bazel

@@ -0,0 +1,14 @@
+load("@rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "go_default_library",
+    srcs = [
+        "mock_store.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"],
+)

submitqueue/extension/conflict/tango/store.go

@@ -0,0 +1,60 @@
+// 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=store.go -destination=mock_store.go -package=tango
+
+import "context"
+
+// SignatureReader reads the target signature of a batch. It is the read-only
+// view of SignatureStore for consumers that must not write.
+type SignatureReader interface {
+	// Get returns the signature of batchID in the bound queue. The bool is
+	// false when no signature has been created for the batch.
+	Get(ctx context.Context, batchID string) (TargetSignature, bool, error)
+}
+
+// SignatureStore persists target signatures. A signature is immutable: it is
+// created once under (Queue, BatchID) and never updated. Reads and writes are
+// per-batch point operations, so any backend can implement it.
+type SignatureStore interface {
+	SignatureReader
+
+	// Create persists signature in one write. Returns an already-exists error
+	// if the bound queue already holds a signature for signature.BatchID, so the
+	// first signature written stays and the caller can read it back with Get.
+	Create(ctx context.Context, signature TargetSignature) error
+}
+
+// DictionaryReader reads the label recorded for a target ID. It is the
+// read-only view of DictionaryStore.
+type DictionaryReader interface {
+	// Get returns the label recorded for id in the bound queue. The bool is
+	// false when none has been recorded.
+	Get(ctx context.Context, id uint64) (TargetLabel, bool, error)
+}
+
+// DictionaryStore persists the target dictionary: one TargetLabel for each
+// 64-bit target ID. A record is immutable: it is created once under
+// (Queue, ID) and never updated. Two labels can share an ID, so the first label
+// recorded stays and the caller can read it back with Get to detect a collision.
+type DictionaryStore interface {
+	DictionaryReader
+
+	// Create persists label in one write. Returns an already-exists error if
+	// the bound queue holds a label for label.ID, whether or not it is the same
+	// label, so repeating a write is harmless.
+	Create(ctx context.Context, label TargetLabel) error
+}

submitqueue/extension/conflict/tango/target_label.go

@@ -0,0 +1,33 @@
+// 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
+
+// TargetLabel is one build target label and the 64-bit ID it hashes to. The
+// whole record is immutable: (Queue, ID) is its identity and there is no update
+// path. Two labels can share an ID on a hash collision; the first one recorded
+// stays.
+type TargetLabel struct {
+	// Queue is the queue the label was seen in. Unique together with ID.
+	Queue string
+
+	// ID is the 64-bit hash of Label.
+	ID uint64
+
+	// Label is the target label exactly as the build graph reported it.
+	Label string
+
+	// CreatedAt is the Unix milliseconds timestamp when the record was created.
+	CreatedAt int64
+}

submitqueue/extension/conflict/tango/target_signature.go

@@ -0,0 +1,45 @@
+// 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
+
+// TargetSignature is the set of build targets a batch changes, as 64-bit IDs.
+// The whole record is immutable: (Queue, BatchID) is its identity and there is
+// no update path.
+type TargetSignature struct {
+	// Queue is the queue the batch belongs to. Unique together with BatchID.
+	Queue string
+
+	// BatchID is the canonical decimal batch identifier, unique within Queue.
+	BatchID string
+
+	// BaseRevision is the commit SHA the changed targets were computed against.
+	BaseRevision string
+
+	// Targets is sorted ascending by ID, with no duplicate IDs.
+	Targets []SignatureTarget
+
+	// CreatedAt is the Unix milliseconds timestamp when the record was created.
+	CreatedAt int64
+}
+
+// SignatureTarget is one changed build target in a TargetSignature.
+type SignatureTarget struct {
+	// ID is the 64-bit hash of the target's label.
+	ID uint64
+
+	// Distance is the distance from the nearest directly changed source in the
+	// reverse dependency graph; 0 means directly changed.
+	Distance int32
+}