diff --git a/stovepipe/extension/storage/BUILD.bazel b/stovepipe/extension/storage/BUILD.bazel
index fc12fdf84..2ebebccaa 100644
--- a/stovepipe/extension/storage/BUILD.bazel
+++ b/stovepipe/extension/storage/BUILD.bazel
@@ -3,6 +3,7 @@ load("@rules_go//go:def.bzl", "go_library", "go_test")
 go_library(
     name = "go_default_library",
     srcs = [
+        "build_issue_store.go",
         "build_store.go",
         "queue_log_store.go",
         "queue_store.go",
diff --git a/stovepipe/extension/storage/README.md b/stovepipe/extension/storage/README.md
index de79c8959..e0777fd6e 100644
--- a/stovepipe/extension/storage/README.md
+++ b/stovepipe/extension/storage/README.md
@@ -1,6 +1,6 @@
 # Storage
 
-Pluggable persistence interfaces for Stovepipe entities (`RequestStore`, `RequestURIStore`, `QueueStore`, `BuildStore`). Implementations live under `extension/storage/<impl>/`.
+Pluggable persistence interfaces for Stovepipe entities (`RequestStore`, `RequestURIStore`, `QueueStore`, `BuildStore`, `BuildIssueStore`). Implementations live under `extension/storage/<impl>/`.
 
 The aggregate is resolved per queue through a factory keyed by queue name, mirroring the extension contract and the [submitqueue storage seam](../../../submitqueue/extension/storage/README.md#queue-scoped-resolution): a resolved instance is bound to its queue, entity arguments whose queue disagrees with the binding are rejected, and reads never surface another queue's records. Stovepipe has no cross-queue read paths, so every store — including `QueueStore`, whose row key is the queue name itself — lives inside the queue-scoped aggregate; there is no global remainder.
 
@@ -23,3 +23,11 @@ Same design space as [`submitqueue/extension/storage`](../../../submitqueue/exte
 `RequestAcceptanceStore` is the ordered lookup mapping for List: immutable `(queue, accepted_at_ms, request_id)` keys with bounded primary-key range scans, not a secondary index or a second status projection. The request-log materializer ensures each known acceptance has a mapping after summary persistence, including retries where the summary is unchanged. Unknown acceptance times are not mapped; historical backfill is separate.
 
 `QueueStore` owns internal enablement alongside pipeline coordination. `QueueSummaryStore` persists the current read model projected from immutable `QueueLogStore` occurrences. Enablement sequences, operational row versions and projection versions are distinct. These stores use primary-key operations; version arithmetic, duplicate reconciliation and projection repair belong to business logic. See [queue state](../../../doc/rfc/stovepipe/queue-state.md).
+
+## Build issue observations
+
+`BuildIssueStore` accumulates immutable observations identified by build, task, and unit within the bound queue. The build ID is supplied separately from the detected issue. Repeated observations return `ErrAlreadyExists`, which callers may treat as successful persistence. Empty unit IDs represent task-wide observations.
+
+Each observation is stored separately, not in a serialized collection. Observations are historical evidence; they do not track whether an issue is currently open or resolved. No update, deletion, or absence-based recovery is implied by this store.
+
+The MySQL primary key contains the queue, build ID, task ID, and unit ID directly as binary strings, preserving byte-exact identity. Their limits are 255, 1020, 255, and 1024 bytes respectively, for a combined maximum of 2554 bytes. Creates and reads reject identifiers exceeding these limits before querying the database; identifiers are never truncated.
diff --git a/stovepipe/extension/storage/build_issue_store.go b/stovepipe/extension/storage/build_issue_store.go
new file mode 100644
index 000000000..8633bc3c9
--- /dev/null
+++ b/stovepipe/extension/storage/build_issue_store.go
@@ -0,0 +1,34 @@
+// 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 storage
+
+//go:generate mockgen -source=build_issue_store.go -destination=mock/build_issue_store_mock.go -package=mock
+
+import (
+	"context"
+
+	"github.com/uber/submitqueue/stovepipe/entity"
+)
+
+// BuildIssueStore retains immutable observations keyed by build, task, and unit
+// within the bound queue. Presence records an observation, not a currently open issue.
+type BuildIssueStore interface {
+	// Create returns ErrAlreadyExists for a previously recorded build/task/unit.
+	// Callers may treat that duplicate as success when accumulating observations.
+	Create(ctx context.Context, buildID string, issue entity.BuildIssue) error
+
+	// Get returns ErrNotFound when the build/task/unit has not been recorded.
+	Get(ctx context.Context, buildID, taskID, unitID string) (entity.BuildIssue, error)
+}
diff --git a/stovepipe/extension/storage/mock/BUILD.bazel b/stovepipe/extension/storage/mock/BUILD.bazel
index dab7cef72..ad9f4504a 100644
--- a/stovepipe/extension/storage/mock/BUILD.bazel
+++ b/stovepipe/extension/storage/mock/BUILD.bazel
@@ -3,6 +3,7 @@ load("@rules_go//go:def.bzl", "go_library")
 go_library(
     name = "go_default_library",
     srcs = [
+        "build_issue_store_mock.go",
         "build_store_mock.go",
         "queue_log_store_mock.go",
         "queue_store_mock.go",
diff --git a/stovepipe/extension/storage/mock/build_issue_store_mock.go b/stovepipe/extension/storage/mock/build_issue_store_mock.go
new file mode 100644
index 000000000..e97faa051
--- /dev/null
+++ b/stovepipe/extension/storage/mock/build_issue_store_mock.go
@@ -0,0 +1,71 @@
+// Code generated by MockGen. DO NOT EDIT.
+// Source: build_issue_store.go
+//
+// Generated by this command:
+//
+//	mockgen -source=build_issue_store.go -destination=mock/build_issue_store_mock.go -package=mock
+//
+
+// Package mock is a generated GoMock package.
+package mock
+
+import (
+	context "context"
+	reflect "reflect"
+
+	entity "github.com/uber/submitqueue/stovepipe/entity"
+	gomock "go.uber.org/mock/gomock"
+)
+
+// MockBuildIssueStore is a mock of BuildIssueStore interface.
+type MockBuildIssueStore struct {
+	ctrl     *gomock.Controller
+	recorder *MockBuildIssueStoreMockRecorder
+	isgomock struct{}
+}
+
+// MockBuildIssueStoreMockRecorder is the mock recorder for MockBuildIssueStore.
+type MockBuildIssueStoreMockRecorder struct {
+	mock *MockBuildIssueStore
+}
+
+// NewMockBuildIssueStore creates a new mock instance.
+func NewMockBuildIssueStore(ctrl *gomock.Controller) *MockBuildIssueStore {
+	mock := &MockBuildIssueStore{ctrl: ctrl}
+	mock.recorder = &MockBuildIssueStoreMockRecorder{mock}
+	return mock
+}
+
+// EXPECT returns an object that allows the caller to indicate expected use.
+func (m *MockBuildIssueStore) EXPECT() *MockBuildIssueStoreMockRecorder {
+	return m.recorder
+}
+
+// Create mocks base method.
+func (m *MockBuildIssueStore) Create(ctx context.Context, buildID string, issue entity.BuildIssue) error {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "Create", ctx, buildID, issue)
+	ret0, _ := ret[0].(error)
+	return ret0
+}
+
+// Create indicates an expected call of Create.
+func (mr *MockBuildIssueStoreMockRecorder) Create(ctx, buildID, issue any) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Create", reflect.TypeOf((*MockBuildIssueStore)(nil).Create), ctx, buildID, issue)
+}
+
+// Get mocks base method.
+func (m *MockBuildIssueStore) Get(ctx context.Context, buildID, taskID, unitID string) (entity.BuildIssue, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "Get", ctx, buildID, taskID, unitID)
+	ret0, _ := ret[0].(entity.BuildIssue)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// Get indicates an expected call of Get.
+func (mr *MockBuildIssueStoreMockRecorder) Get(ctx, buildID, taskID, unitID any) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Get", reflect.TypeOf((*MockBuildIssueStore)(nil).Get), ctx, buildID, taskID, unitID)
+}
diff --git a/stovepipe/extension/storage/mock/storage_mock.go b/stovepipe/extension/storage/mock/storage_mock.go
index 11d137b25..b39ce22d7 100644
--- a/stovepipe/extension/storage/mock/storage_mock.go
+++ b/stovepipe/extension/storage/mock/storage_mock.go
@@ -79,6 +79,20 @@ func (m *MockStorage) EXPECT() *MockStorageMockRecorder {
 	return m.recorder
 }
 
+// GetBuildIssueStore mocks base method.
+func (m *MockStorage) GetBuildIssueStore() storage.BuildIssueStore {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "GetBuildIssueStore")
+	ret0, _ := ret[0].(storage.BuildIssueStore)
+	return ret0
+}
+
+// GetBuildIssueStore indicates an expected call of GetBuildIssueStore.
+func (mr *MockStorageMockRecorder) GetBuildIssueStore() *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetBuildIssueStore", reflect.TypeOf((*MockStorage)(nil).GetBuildIssueStore))
+}
+
 // GetBuildStore mocks base method.
 func (m *MockStorage) GetBuildStore() storage.BuildStore {
 	m.ctrl.T.Helper()
diff --git a/stovepipe/extension/storage/mysql/BUILD.bazel b/stovepipe/extension/storage/mysql/BUILD.bazel
index 26edd5e8b..25a1344f7 100644
--- a/stovepipe/extension/storage/mysql/BUILD.bazel
+++ b/stovepipe/extension/storage/mysql/BUILD.bazel
@@ -3,6 +3,7 @@ load("@rules_go//go:def.bzl", "go_library", "go_test")
 go_library(
     name = "go_default_library",
     srcs = [
+        "build_issue_store.go",
         "build_store.go",
         "queue_log_store.go",
         "queue_store.go",
@@ -29,6 +30,7 @@ go_library(
 go_test(
     name = "go_default_test",
     srcs = [
+        "build_issue_store_test.go",
         "build_store_test.go",
         "queue_store_test.go",
         "queue_summary_store_test.go",
diff --git a/stovepipe/extension/storage/mysql/build_issue_store.go b/stovepipe/extension/storage/mysql/build_issue_store.go
new file mode 100644
index 000000000..a7c825b38
--- /dev/null
+++ b/stovepipe/extension/storage/mysql/build_issue_store.go
@@ -0,0 +1,106 @@
+// 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 mysql
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"fmt"
+
+	"github.com/uber-go/tally"
+
+	"github.com/uber/submitqueue/platform/metrics"
+	"github.com/uber/submitqueue/stovepipe/entity"
+	"github.com/uber/submitqueue/stovepipe/extension/storage"
+)
+
+type buildIssueStore struct {
+	db    *sql.DB
+	scope tally.Scope
+	queue string
+}
+
+// NewBuildIssueStore binds observations to queue over the shared database.
+func NewBuildIssueStore(db *sql.DB, scope tally.Scope, queue string) storage.BuildIssueStore {
+	return &buildIssueStore{db: db, scope: scope, queue: queue}
+}
+
+func (s *buildIssueStore) Create(ctx context.Context, buildID string, issue entity.BuildIssue) (retErr error) {
+	op := metrics.Begin(s.scope, "create", metrics.StorageLatencyBuckets)
+	defer func() { op.Complete(retErr) }()
+
+	if err := validateBuildIssueKey(s.queue, buildID, issue.TaskID, issue.UnitID); err != nil {
+		return err
+	}
+	_, err := s.db.ExecContext(ctx,
+		`INSERT INTO build_issue (queue, build_id, task_id, unit_id)
+         VALUES (?, ?, ?, ?)`,
+		s.queue, buildID, issue.TaskID, issue.UnitID,
+	)
+	if err != nil {
+		if isDuplicateEntry(err) {
+			return fmt.Errorf("build issue build=%q task=%q unit=%q: %w", buildID, issue.TaskID, issue.UnitID, storage.ErrAlreadyExists)
+		}
+
+		return fmt.Errorf("failed to create build issue build=%q task=%q unit=%q: %w", buildID, issue.TaskID, issue.UnitID, err)
+	}
+
+	return nil
+}
+
+func (s *buildIssueStore) Get(ctx context.Context, buildID, taskID, unitID string) (ret entity.BuildIssue, retErr error) {
+	op := metrics.Begin(s.scope, "get", metrics.StorageLatencyBuckets)
+	defer func() { op.Complete(retErr) }()
+
+	if err := validateBuildIssueKey(s.queue, buildID, taskID, unitID); err != nil {
+		return entity.BuildIssue{}, err
+	}
+
+	var issue entity.BuildIssue
+	err := s.db.QueryRowContext(ctx,
+		`SELECT task_id, unit_id FROM build_issue
+         WHERE queue = ? AND build_id = ? AND task_id = ? AND unit_id = ?`,
+		s.queue, buildID, taskID, unitID,
+	).Scan(&issue.TaskID, &issue.UnitID)
+	if errors.Is(err, sql.ErrNoRows) {
+		return entity.BuildIssue{}, storage.WrapNotFound(err)
+	}
+
+	if err != nil {
+		return entity.BuildIssue{}, fmt.Errorf("failed to get build issue build=%q task=%q unit=%q: %w", buildID, taskID, unitID, err)
+	}
+
+	return issue, nil
+}
+
+func validateBuildIssueKey(queue, buildID, taskID, unitID string) error {
+	for _, field := range []struct {
+		name     string
+		value    string
+		maxBytes int
+	}{
+		{"queue", queue, 255},
+		{"build ID", buildID, 1020},
+		{"task ID", taskID, 255},
+		{"unit ID", unitID, 1024},
+	} {
+		if len(field.value) > field.maxBytes {
+			return fmt.Errorf("build issue %s exceeds %d-byte limit", field.name, field.maxBytes)
+		}
+	}
+
+	return nil
+}
diff --git a/stovepipe/extension/storage/mysql/build_issue_store_test.go b/stovepipe/extension/storage/mysql/build_issue_store_test.go
new file mode 100644
index 000000000..47eeddc6f
--- /dev/null
+++ b/stovepipe/extension/storage/mysql/build_issue_store_test.go
@@ -0,0 +1,164 @@
+// 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 mysql
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"regexp"
+	"strings"
+	"testing"
+
+	"github.com/DATA-DOG/go-sqlmock"
+	"github.com/go-sql-driver/mysql"
+	"github.com/stretchr/testify/require"
+
+	"github.com/uber/submitqueue/stovepipe/entity"
+	"github.com/uber/submitqueue/stovepipe/extension/storage"
+)
+
+func TestBuildIssueStoreCreate(t *testing.T) {
+	dbErr := errors.New("database unavailable")
+
+	for _, tt := range []struct {
+		name    string
+		unitID  string
+		dbErr   error
+		wantErr error
+	}{
+		{name: "unit observation", unitID: "unit"},
+		{name: "task-wide observation"},
+		{name: "long unit identifier", unitID: strings.Repeat("u", 1024)},
+		{name: "duplicate observation", unitID: "unit", dbErr: &mysql.MySQLError{Number: mysqlErrDuplicateEntry}, wantErr: storage.ErrAlreadyExists},
+		{name: "dependency error", unitID: "unit", dbErr: dbErr, wantErr: dbErr},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			db, mock, err := sqlmock.New()
+			require.NoError(t, err)
+			defer db.Close()
+
+			store := NewBuildIssueStore(db, testMetrics(), "queue")
+			issue := entity.BuildIssue{TaskID: "task", UnitID: tt.unitID}
+
+			expectation := mock.ExpectExec(regexp.QuoteMeta(`INSERT INTO build_issue (queue, build_id, task_id, unit_id) VALUES (?, ?, ?, ?)`)).
+				WithArgs("queue", "build", issue.TaskID, issue.UnitID)
+			if tt.dbErr != nil {
+				expectation.WillReturnError(tt.dbErr)
+			} else {
+				expectation.WillReturnResult(sqlmock.NewResult(0, 1))
+			}
+
+			err = store.Create(context.Background(), "build", issue)
+			if tt.wantErr != nil {
+				require.ErrorIs(t, err, tt.wantErr)
+			} else {
+				require.NoError(t, err)
+			}
+
+			require.NoError(t, mock.ExpectationsWereMet())
+		})
+	}
+}
+
+func TestBuildIssueStoreGet(t *testing.T) {
+	dbErr := errors.New("database unavailable")
+
+	for _, tt := range []struct {
+		name     string
+		unitID   string
+		queryErr error
+		scanErr  bool
+		wantErr  error
+	}{
+		{name: "unit observation", unitID: "unit"},
+		{name: "task-wide observation"},
+		{name: "missing observation", unitID: "unit", queryErr: sql.ErrNoRows, wantErr: storage.ErrNotFound},
+		{name: "dependency error", unitID: "unit", queryErr: dbErr, wantErr: dbErr},
+		{name: "scan error", unitID: "unit", scanErr: true},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			db, mock, err := sqlmock.New()
+			require.NoError(t, err)
+			defer db.Close()
+
+			store := NewBuildIssueStore(db, testMetrics(), "queue")
+			issue := entity.BuildIssue{TaskID: "task", UnitID: tt.unitID}
+
+			expectation := mock.ExpectQuery(regexp.QuoteMeta(`SELECT task_id, unit_id FROM build_issue WHERE queue = ? AND build_id = ? AND task_id = ? AND unit_id = ?`)).
+				WithArgs("queue", "build", issue.TaskID, issue.UnitID)
+			if tt.queryErr != nil {
+				expectation.WillReturnError(tt.queryErr)
+			} else if tt.scanErr {
+				expectation.WillReturnRows(sqlmock.NewRows([]string{"task_id", "unit_id"}).AddRow(nil, issue.UnitID))
+			} else {
+				expectation.WillReturnRows(sqlmock.NewRows([]string{"task_id", "unit_id"}).AddRow(issue.TaskID, issue.UnitID))
+			}
+
+			got, err := store.Get(context.Background(), "build", issue.TaskID, issue.UnitID)
+			if tt.wantErr != nil {
+				require.ErrorIs(t, err, tt.wantErr)
+			} else if tt.scanErr {
+				require.Error(t, err)
+			} else {
+				require.NoError(t, err)
+				require.Equal(t, issue, got)
+			}
+
+			if tt.wantErr != nil || tt.scanErr {
+				require.Equal(t, entity.BuildIssue{}, got)
+			}
+
+			require.NoError(t, mock.ExpectationsWereMet())
+		})
+	}
+}
+
+func TestBuildIssueStoreRejectsOversizedIdentifiers(t *testing.T) {
+	for _, tt := range []struct {
+		name    string
+		queue   string
+		buildID string
+		issue   entity.BuildIssue
+	}{
+		{name: "queue", queue: strings.Repeat("q", 256), buildID: "build", issue: entity.BuildIssue{TaskID: "task"}},
+		{name: "build ID", queue: "queue", buildID: strings.Repeat("b", 1021), issue: entity.BuildIssue{TaskID: "task"}},
+		{name: "task ID", queue: "queue", buildID: "build", issue: entity.BuildIssue{TaskID: strings.Repeat("t", 256)}},
+		{name: "unit ID", queue: "queue", buildID: "build", issue: entity.BuildIssue{TaskID: "task", UnitID: strings.Repeat("u", 1025)}},
+		{name: "multibyte task ID", queue: "queue", buildID: "build", issue: entity.BuildIssue{TaskID: strings.Repeat("é", 128)}},
+		{name: "multibyte unit ID", queue: "queue", buildID: "build", issue: entity.BuildIssue{TaskID: "task", UnitID: strings.Repeat("😀", 257)}},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			db, mock, err := sqlmock.New()
+			require.NoError(t, err)
+			defer db.Close()
+
+			store := NewBuildIssueStore(db, testMetrics(), tt.queue)
+
+			// SQL would succeed, so rejection must come from identifier validation.
+			mock.MatchExpectationsInOrder(false)
+			mock.ExpectExec("INSERT INTO build_issue").WillReturnResult(sqlmock.NewResult(0, 1))
+			mock.ExpectQuery("SELECT task_id, unit_id FROM build_issue").WillReturnRows(
+				sqlmock.NewRows([]string{"task_id", "unit_id"}).AddRow(tt.issue.TaskID, tt.issue.UnitID),
+			)
+
+			require.Error(t, store.Create(context.Background(), tt.buildID, tt.issue))
+
+			got, err := store.Get(context.Background(), tt.buildID, tt.issue.TaskID, tt.issue.UnitID)
+			require.Error(t, err)
+			require.Equal(t, entity.BuildIssue{}, got)
+		})
+	}
+}
diff --git a/stovepipe/extension/storage/mysql/schema/build_issue.sql b/stovepipe/extension/storage/mysql/schema/build_issue.sql
new file mode 100644
index 000000000..b50fdde18
--- /dev/null
+++ b/stovepipe/extension/storage/mysql/schema/build_issue.sql
@@ -0,0 +1,11 @@
+-- One immutable observation per (queue, build, task, unit), not an open-issue projection.
+-- Binary identifiers preserve byte-exact identity; the full key is at most 2554 bytes.
+CREATE TABLE IF NOT EXISTS build_issue (
+    queue       VARBINARY(255) NOT NULL,
+    build_id    VARBINARY(1020) NOT NULL, -- Accommodates existing VARCHAR(255) utf8mb4 build IDs.
+
+    task_id     VARBINARY(255) NOT NULL,
+    unit_id     VARBINARY(1024) NOT NULL,
+
+    PRIMARY KEY (queue, build_id, task_id, unit_id)
+) ENGINE=InnoDB;
diff --git a/stovepipe/extension/storage/mysql/storage.go b/stovepipe/extension/storage/mysql/storage.go
index e3961c95a..5acb6e87d 100644
--- a/stovepipe/extension/storage/mysql/storage.go
+++ b/stovepipe/extension/storage/mysql/storage.go
@@ -55,6 +55,7 @@ func (s *Storage) For(queueName string) (storage.Storage, error) {
 		queueLogStore:          NewQueueLogStore(s.db, queueScope.SubScope("queue_log_store"), queueName),
 		queueStore:             NewQueueStore(s.db, queueScope.SubScope("queue_store"), queueName),
 		buildStore:             NewBuildStore(s.db, queueScope.SubScope("build_store"), queueName),
+		buildIssueStore:        NewBuildIssueStore(s.db, queueScope.SubScope("build_issue_store"), queueName),
 		validationFactStore:    NewValidationFactStore(s.db, queueScope.SubScope("validation_fact_store"), queueName),
 	}, nil
 }
@@ -75,6 +76,7 @@ type mysqlStorage struct {
 	queueSummaryStore      storage.QueueSummaryStore
 	queueLogStore          storage.QueueLogStore
 	buildStore             storage.BuildStore
+	buildIssueStore        storage.BuildIssueStore
 	validationFactStore    storage.ValidationFactStore
 }
 
@@ -126,3 +128,7 @@ func (f *mysqlStorage) GetQueueSummaryStore() storage.QueueSummaryStore { return
 func (f *mysqlStorage) GetQueueLogStore() storage.QueueLogStore {
 	return f.queueLogStore
 }
+
+func (f *mysqlStorage) GetBuildIssueStore() storage.BuildIssueStore {
+	return f.buildIssueStore
+}
diff --git a/stovepipe/extension/storage/mysql/storage_test.go b/stovepipe/extension/storage/mysql/storage_test.go
index b80f5017c..326070bd1 100644
--- a/stovepipe/extension/storage/mysql/storage_test.go
+++ b/stovepipe/extension/storage/mysql/storage_test.go
@@ -47,6 +47,7 @@ func TestNewStorage(t *testing.T) {
 	assert.NotNil(t, bound.GetRequestSummaryStore())
 	assert.NotNil(t, bound.GetQueueStore())
 	assert.NotNil(t, bound.GetBuildStore())
+	assert.NotNil(t, bound.GetBuildIssueStore())
 
 	_, err = s.For("")
 	assert.Error(t, err, "resolving an empty queue name must fail")
@@ -127,6 +128,14 @@ func TestStorageForQueueMetrics(t *testing.T) {
 				return err
 			},
 		},
+		{
+			name: "build_issue_store",
+			op:   "get",
+			read: func(bound storage.Storage, _ string) error {
+				_, err := bound.GetBuildIssueStore().Get(context.Background(), "build-id", "task", "unit")
+				return err
+			},
+		},
 		{
 			name: "validation_fact_store",
 			op:   "get",
diff --git a/stovepipe/extension/storage/storage.go b/stovepipe/extension/storage/storage.go
index f0bb5d079..21b9886b6 100644
--- a/stovepipe/extension/storage/storage.go
+++ b/stovepipe/extension/storage/storage.go
@@ -94,6 +94,9 @@ type Storage interface {
 	// GetBuildStore returns the BuildStore instance.
 	GetBuildStore() BuildStore
 
+	// GetBuildIssueStore returns the BuildIssueStore instance.
+	GetBuildIssueStore() BuildIssueStore
+
 	// GetValidationFactStore returns the ValidationFactStore instance.
 	GetValidationFactStore() ValidationFactStore
 }
diff --git a/test/integration/stovepipe/extension/storage/mysql/BUILD.bazel b/test/integration/stovepipe/extension/storage/mysql/BUILD.bazel
index 408c73051..758f35ad9 100644
--- a/test/integration/stovepipe/extension/storage/mysql/BUILD.bazel
+++ b/test/integration/stovepipe/extension/storage/mysql/BUILD.bazel
@@ -3,6 +3,7 @@ load("@rules_go//go:def.bzl", "go_test")
 go_test(
     name = "go_default_test",
     srcs = [
+        "build_issue_test.go",
         "queue_state_transitions_test.go",
         "queue_summary_test.go",
         "request_acceptance_test.go",
diff --git a/test/integration/stovepipe/extension/storage/mysql/build_issue_test.go b/test/integration/stovepipe/extension/storage/mysql/build_issue_test.go
new file mode 100644
index 000000000..f877fe7d8
--- /dev/null
+++ b/test/integration/stovepipe/extension/storage/mysql/build_issue_test.go
@@ -0,0 +1,183 @@
+// 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 mysql
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/uber/submitqueue/stovepipe/entity"
+	"github.com/uber/submitqueue/stovepipe/extension/storage"
+)
+
+func testBuildIssueStore(t *testing.T, ctx context.Context, db *sql.DB, factory storage.Factory) {
+	t.Helper()
+
+	bound, err := factory.For(storage.Config{QueueName: "issues/main"})
+	require.NoError(t, err)
+	store := bound.GetBuildIssueStore()
+
+	fixtures := []entity.BuildIssue{
+		{TaskID: "validation", UnitID: "unit"},
+		{TaskID: "validation", UnitID: "Unit"},
+		{TaskID: "validation", UnitID: "unit "},
+		{TaskID: "Validation", UnitID: "unit"},
+		{TaskID: "validation ", UnitID: "unit"},
+		{TaskID: "validation"},
+		{TaskID: "other", UnitID: "unit"},
+		{TaskID: "a\x00b", UnitID: "c"},
+		{TaskID: "a", UnitID: "b\x00c"},
+		{TaskID: strings.Repeat("検証", 42), UnitID: strings.Repeat("対象/", 146)},
+	}
+
+	for _, issue := range fixtures {
+		require.NoError(t, store.Create(ctx, "build", issue))
+		require.ErrorIs(t, store.Create(ctx, "build", issue), storage.ErrAlreadyExists)
+
+		got, err := store.Get(ctx, "build", issue.TaskID, issue.UnitID)
+		require.NoError(t, err)
+		require.Equal(t, issue, got)
+	}
+
+	var count int
+	require.NoError(t, db.QueryRowContext(ctx, "SELECT COUNT(*) FROM build_issue WHERE queue = ? AND build_id = ?", "issues/main", "build").Scan(&count))
+	require.Equal(t, len(fixtures), count)
+
+	issue := fixtures[0]
+	for _, buildID := range []string{"next-build", "Build", "build "} {
+		_, err := store.Get(ctx, buildID, issue.TaskID, issue.UnitID)
+		require.ErrorIs(t, err, storage.ErrNotFound)
+
+		require.NoError(t, store.Create(ctx, buildID, issue))
+
+		got, err := store.Get(ctx, buildID, issue.TaskID, issue.UnitID)
+		require.NoError(t, err)
+		require.Equal(t, issue, got)
+	}
+
+	for _, queue := range []string{"issues/other", "Issues/main", "issues/main "} {
+		other, err := factory.For(storage.Config{QueueName: queue})
+		require.NoError(t, err)
+		_, err = other.GetBuildIssueStore().Get(ctx, "build", issue.TaskID, issue.UnitID)
+		require.ErrorIs(t, err, storage.ErrNotFound)
+
+		require.NoError(t, other.GetBuildIssueStore().Create(ctx, "build", issue))
+
+		got, err := other.GetBuildIssueStore().Get(ctx, "build", issue.TaskID, issue.UnitID)
+		require.NoError(t, err)
+		require.Equal(t, issue, got)
+	}
+
+	for _, missing := range []entity.BuildIssue{
+		{TaskID: "missing", UnitID: "unit"},
+		{TaskID: "validation", UnitID: "missing"},
+		{TaskID: "other"},
+	} {
+		_, err := store.Get(ctx, "build", missing.TaskID, missing.UnitID)
+		require.ErrorIs(t, err, storage.ErrNotFound)
+	}
+
+	t.Run("full primary key at byte limits", func(t *testing.T) {
+		maxQueue := strings.Repeat("q", 255)
+		maxBuildID := strings.Repeat("😀", 255)
+		maxIssue := entity.BuildIssue{TaskID: strings.Repeat("é", 127) + "t", UnitID: strings.Repeat("😀", 256)}
+
+		maxBound, err := factory.For(storage.Config{QueueName: maxQueue})
+		require.NoError(t, err)
+		maxStore := maxBound.GetBuildIssueStore()
+
+		require.NoError(t, maxStore.Create(ctx, maxBuildID, maxIssue))
+		require.ErrorIs(t, maxStore.Create(ctx, maxBuildID, maxIssue), storage.ErrAlreadyExists)
+
+		got, err := maxStore.Get(ctx, maxBuildID, maxIssue.TaskID, maxIssue.UnitID)
+		require.NoError(t, err)
+		require.Equal(t, maxIssue, got)
+
+		for _, tt := range []struct {
+			name    string
+			queue   string
+			buildID string
+			issue   entity.BuildIssue
+		}{
+			{name: "queue", queue: maxQueue + "q", buildID: maxBuildID, issue: maxIssue},
+			{name: "build ID", queue: maxQueue, buildID: maxBuildID + "b", issue: maxIssue},
+			{name: "task ID", queue: maxQueue, buildID: maxBuildID, issue: entity.BuildIssue{TaskID: maxIssue.TaskID + "t", UnitID: maxIssue.UnitID}},
+			{name: "unit ID", queue: maxQueue, buildID: maxBuildID, issue: entity.BuildIssue{TaskID: maxIssue.TaskID, UnitID: maxIssue.UnitID + "u"}},
+		} {
+			t.Run("reject oversized "+tt.name, func(t *testing.T) {
+				invalidBound, err := factory.For(storage.Config{QueueName: tt.queue})
+				require.NoError(t, err)
+				invalidStore := invalidBound.GetBuildIssueStore()
+
+				err = invalidStore.Create(ctx, tt.buildID, tt.issue)
+				require.Error(t, err)
+				require.NotErrorIs(t, err, storage.ErrAlreadyExists)
+
+				_, err = invalidStore.Get(ctx, tt.buildID, tt.issue.TaskID, tt.issue.UnitID)
+				require.Error(t, err)
+				require.NotErrorIs(t, err, storage.ErrNotFound)
+			})
+		}
+
+		require.NoError(t, db.QueryRowContext(ctx, "SELECT COUNT(*) FROM build_issue WHERE queue = ?", maxQueue).Scan(&count))
+		require.Equal(t, 1, count)
+
+		got, err = maxStore.Get(ctx, maxBuildID, maxIssue.TaskID, maxIssue.UnitID)
+		require.NoError(t, err)
+		require.Equal(t, maxIssue, got)
+	})
+
+	t.Run("accumulate individual observations", func(t *testing.T) {
+		for i := 0; i < 128; i++ {
+			issue := entity.BuildIssue{TaskID: "validation", UnitID: fmt.Sprintf("unit-%d", i)}
+			require.NoError(t, store.Create(ctx, "many-issues", issue))
+
+			got, err := store.Get(ctx, "many-issues", issue.TaskID, issue.UnitID)
+			require.NoError(t, err)
+			require.Equal(t, issue, got)
+		}
+
+		require.NoError(t, db.QueryRowContext(ctx, "SELECT COUNT(*) FROM build_issue WHERE queue = ? AND build_id = ?", "issues/main", "many-issues").Scan(&count))
+		require.Equal(t, 128, count)
+	})
+
+	t.Run("concurrent duplicate observations", func(t *testing.T) {
+		const writers = 8
+		results := make(chan error, writers)
+		for i := 0; i < writers; i++ {
+			go func() { results <- store.Create(ctx, "concurrent", issue) }()
+		}
+
+		created := 0
+		for i := 0; i < writers; i++ {
+			if err := <-results; err == nil {
+				created++
+			} else {
+				require.ErrorIs(t, err, storage.ErrAlreadyExists)
+			}
+		}
+
+		require.Equal(t, 1, created)
+
+		got, err := store.Get(ctx, "concurrent", issue.TaskID, issue.UnitID)
+		require.NoError(t, err)
+		require.Equal(t, issue, got)
+	})
+}
diff --git a/test/integration/stovepipe/extension/storage/mysql/storage_test.go b/test/integration/stovepipe/extension/storage/mysql/storage_test.go
index fc93afcaf..cd734ffb5 100644
--- a/test/integration/stovepipe/extension/storage/mysql/storage_test.go
+++ b/test/integration/stovepipe/extension/storage/mysql/storage_test.go
@@ -90,6 +90,11 @@ func TestMySQLStorage(t *testing.T) {
 		suite.Run(t, testSuite)
 	})
 
+	t.Run("BuildIssueStore", func(t *testing.T) {
+		resetStorage(t, db)
+		testBuildIssueStore(t, ctx, db, factory)
+	})
+
 	t.Run("BuildStore", func(t *testing.T) {
 		resetStorage(t, db)
 		testSuite := new(MySQLBuildStoreSuite)
@@ -151,6 +156,7 @@ func resetStorage(t *testing.T, db *sql.DB) {
 		"TRUNCATE TABLE request_uri",
 		"TRUNCATE TABLE request",
 		"TRUNCATE TABLE build",
+		"TRUNCATE TABLE build_issue",
 		"TRUNCATE TABLE queue",
 		"TRUNCATE TABLE validation_fact",
 	} {