015 add tracing

app/config.py

@@ -48,6 +48,13 @@ class AdapterConfig(BaseModel):
     cdek_cache_ttl_seconds: int = Field(default=900, gt=0)
 
 
+class ObservabilityConfig(BaseModel):
+    enabled: bool = False
+    service_name: str = Field(..., min_length=1)
+    otlp_endpoint: str = Field(..., min_length=1)
+    otlp_insecure: bool = True
+
+
 class Settings(BaseSettings):
     model_config = SettingsConfigDict(
         extra="ignore",
@@ -58,6 +65,7 @@ class Settings(BaseSettings):
     business_logic: BusinessLogicConfig = Field(default_factory=BusinessLogicConfig)
     repository: RepositoryConfig = Field(default_factory=RepositoryConfig)
     adapter: AdapterConfig = Field(default_factory=AdapterConfig)
+    observability: ObservabilityConfig
 
     @classmethod
     def settings_customise_sources(
@@ -85,6 +93,7 @@ class _RequiredYamlSections(BaseModel):
     business_logic: dict[str, Any]
     repository: dict[str, Any]
     adapter: dict[str, Any]
+    observability: dict[str, Any]
 
 
 def _resolve_runtime_config_file() -> str:

app/main.py

@@ -5,6 +5,7 @@ from fastapi import FastAPI
 from app.config import Settings, get_settings
 from app.controllers.v1.delivery import router as delivery_router
 from app.runtime.logging import configure_logging
+from app.runtime.tracing import configure_tracing
 
 
 def create_app(settings: Settings | None = None) -> FastAPI:
@@ -15,6 +16,7 @@ def create_app(settings: Settings | None = None) -> FastAPI:
     application.state.settings = resolved_settings
 
     application.include_router(delivery_router, prefix=resolved_settings.controller.api_prefix)
+    configure_tracing(application, resolved_settings.observability)
     return application
 
 

app/runtime/tracing.py

@@ -0,0 +1,75 @@
+"""Centralized runtime OpenTelemetry tracing bootstrap."""
+
+from fastapi import FastAPI
+from opentelemetry import trace
+from opentelemetry.exporter.otlp.proto.grpc.trace_exporter import OTLPSpanExporter
+from opentelemetry.instrumentation.fastapi import FastAPIInstrumentor
+from opentelemetry.instrumentation.httpx import HTTPXClientInstrumentor
+from opentelemetry.instrumentation.redis import RedisInstrumentor
+from opentelemetry.sdk.resources import Resource
+from opentelemetry.sdk.trace import TracerProvider
+from opentelemetry.sdk.trace.export import BatchSpanProcessor
+
+from app.config import ObservabilityConfig
+
+_HTTPX_INSTRUMENTOR = HTTPXClientInstrumentor()
+_REDIS_INSTRUMENTOR = RedisInstrumentor()
+_TRACER_PROVIDER: TracerProvider | None = None
+
+
+def configure_tracing(app: FastAPI, observability: ObservabilityConfig) -> None:
+    if not observability.enabled:
+        return
+
+    tracer_provider = _get_or_create_tracer_provider(observability)
+    _instrument_fastapi_app(app, tracer_provider=tracer_provider)
+    _instrument_httpx(tracer_provider=tracer_provider)
+    _instrument_redis(tracer_provider=tracer_provider)
+
+
+def _get_or_create_tracer_provider(observability: ObservabilityConfig) -> TracerProvider:
+    global _TRACER_PROVIDER
+
+    if _TRACER_PROVIDER is not None:
+        return _TRACER_PROVIDER
+
+    tracer_provider = _build_tracer_provider(observability)
+    trace.set_tracer_provider(tracer_provider)
+    _TRACER_PROVIDER = tracer_provider
+    return tracer_provider
+
+
+def _build_tracer_provider(observability: ObservabilityConfig) -> TracerProvider:
+    exporter = _build_span_exporter(observability)
+    tracer_provider = TracerProvider(resource=_build_resource(observability))
+    tracer_provider.add_span_processor(BatchSpanProcessor(exporter))
+    return tracer_provider
+
+
+def _build_span_exporter(observability: ObservabilityConfig) -> OTLPSpanExporter:
+    return OTLPSpanExporter(
+        endpoint=observability.otlp_endpoint,
+        insecure=observability.otlp_insecure,
+    )
+
+
+def _build_resource(observability: ObservabilityConfig) -> Resource:
+    return Resource.create({"service.name": observability.service_name})
+
+
+def _instrument_fastapi_app(app: FastAPI, *, tracer_provider: TracerProvider) -> None:
+    if getattr(app, "_is_instrumented_by_opentelemetry", False):
+        return
+    FastAPIInstrumentor.instrument_app(app, tracer_provider=tracer_provider)
+
+
+def _instrument_httpx(*, tracer_provider: TracerProvider) -> None:
+    if _HTTPX_INSTRUMENTOR.is_instrumented_by_opentelemetry:
+        return
+    _HTTPX_INSTRUMENTOR.instrument(tracer_provider=tracer_provider)
+
+
+def _instrument_redis(*, tracer_provider: TracerProvider) -> None:
+    if _REDIS_INSTRUMENTOR.is_instrumented_by_opentelemetry:
+        return
+    _REDIS_INSTRUMENTOR.instrument(tracer_provider=tracer_provider)

config.example.yaml

@@ -22,3 +22,9 @@ adapter:
   cdek_retry_backoff_seconds: 0.2
   cdek_timeout_seconds: 10.0
   cdek_cache_ttl_seconds: 900
+
+observability:
+  enabled: false
+  service_name: "g2s-aggregator"
+  otlp_endpoint: "http://localhost:4317"
+  otlp_insecure: true

config.test.yaml

@@ -22,3 +22,9 @@ adapter:
   cdek_retry_backoff_seconds: 0.2
   cdek_timeout_seconds: 10.0
   cdek_cache_ttl_seconds: 900
+
+observability:
+  enabled: false
+  service_name: "g2s-aggregator-test"
+  otlp_endpoint: "http://localhost:4317"
+  otlp_insecure: true

spec/index.md

@@ -1,7 +1,7 @@
 # Spec Tasks Index
 
 > ⚠️ This file is generated. Do not edit manually.
-> Generated at (UTC): `2026-03-13T14:18:34+00:00`
+> Generated at (UTC): `2026-03-13T14:21:47+00:00`
 
 ## Tasks
 
@@ -22,9 +22,10 @@
 | 012 | DONE | 2026-03-08 | Remove observability and SigNoz stack for phase 1 | `spec/tasks/012_remove_observability_and_signoz_for_phase1.md` |
 | 013 | DONE | 2026-03-09 | Add configurable provider price multiplier in domain logic | `spec/tasks/013_add_configurable_provider_price_multiplier.md` |
 | 014 | DONE | 2026-03-12 | Add minimal structlog JSON logging | `spec/tasks/014_add_minimal_structlog_json_logging.md` |
+| 015 | TODO | 2026-03-13 | Add minimal OpenTelemetry tracing | `spec/tasks/015_add_minimal_opentelemetry_tracing.md` |
 
 ## Summary
 
-- Total: **15**
+- Total: **16**
-- TODO: **0**
+- TODO: **1**
 - DONE: **15**

spec/tasks/015_add_minimal_opentelemetry_tracing.md

@@ -0,0 +1,50 @@
+---
+id: 015
+title: Add minimal OpenTelemetry tracing
+status: TODO
+created: 2026-03-13
+---
+
+## Context
+После удаления observability stack в задаче `012` runtime-приложение осталось без трассировки. Появилось новое требование: вернуть только минимальный tracing для входящих HTTP-запросов и исходящих вызовов провайдера/Redis, без возврата metrics, alerting и trace/log correlation.
+
+## Goal
+Подключить минимальный OpenTelemetry tracing через централизованный runtime bootstrap: настроить `TracerProvider` и OTLP exporter из YAML-конфига, добавить instrumentation для FastAPI, httpx и Redis и встроить этот bootstrap в startup приложения без переноса telemetry concern в Business Logic.
+
+## Constraints
+- Соблюдать layered architecture из `AGENTS.md`.
+- Scope задачи: только tracing bootstrap, YAML configuration, instrumentation wiring и тесты на это поведение.
+- Не добавлять metrics, request correlation middleware, `request_id`, `trace_id` в логи, SigNoz, Telegram alerting и иные observability features кроме tracing.
+- Не добавлять business rules, branching или data access в runtime tracing bootstrap.
+- Инициализация OpenTelemetry должна жить в отдельном runtime-модуле или app startup; Controller, Service, Repository, Adapter и Business Logic не должны вручную создавать exporter/provider.
+- Конфигурация tracing должна читаться из отдельной секции `observability` в YAML-файлах конфигурации.
+- Bootstrap tracing должен быть идемпотентным: повторные вызовы `create_app()` в тестах не должны дублировать global instrumentation и span processors.
+- Не изменять API contract, логику расчета тарифов, кэш semantics и provider protocol.
+- Не изменять файлы в `spec/`.
+
+## Acceptance criteria
+- В конфигурации приложения добавлена секция `observability` с параметрами включения tracing, `service_name`, OTLP endpoint и флагом insecure transport.
+- При `observability.enabled = true` приложение на старте создает `TracerProvider` с `Resource(service.name=...)` и OTLP exporter, используя значения из YAML-конфига.
+- При `observability.enabled = true` централизованно включается instrumentation для FastAPI, httpx и Redis.
+- При `observability.enabled = false` приложение стартует без инициализации exporter/provider и без регистрации instrumentation.
+- Повторное создание приложения или повторный вызов tracing bootstrap не приводит к duplicate instrumentation/span processor registration.
+- Реализация не восстанавливает metrics, alerts, request/log correlation и не меняет JSON logging contract.
+
+## Definition of Done
+- [ ] Добавлена секция `observability` в config schema и runtime YAML-файлы.
+- [ ] Реализован централизованный runtime bootstrap для OpenTelemetry tracing.
+- [ ] `create_app()` подключает tracing bootstrap без бизнес-логики и без дублирования инициализации.
+- [ ] Добавлены tests на конфигурацию, enabled/disabled режимы и идемпотентность tracing setup.
+- [ ] Добавлен tracing test, подтверждающий создание spans для FastAPI/httpx/Redis instrumentation или корректный wiring этих instrumentors.
+
+## Tests
+- Обновить `tests/config/test_config_sections.py` для проверки секции `observability`, обязательных полей и disabled/enabled конфигурации.
+- Обновить `tests/smoke/test_app_import.py` для проверки вызова централизованного tracing bootstrap при создании app.
+- Добавить `tests/tracing/test_bootstrap.py` для проверки OTLP exporter/provider setup, `service.name`, enabled/disabled режимов и идемпотентности instrumentation.
+- Добавить tracing test с in-memory exporter или эквивалентным deterministic harness для проверки, что FastAPI/httpx/Redis instrumentation корректно подключается без запуска внешнего OTLP collector.
+
+## Commands
+- `poetry run pytest tests/config/test_config_sections.py -q`
+- `poetry run pytest tests/smoke/test_app_import.py -q`
+- `poetry run pytest tests/tracing/test_bootstrap.py -q`
+- `python3 spec/gen_spec_index.py --check`

tests/adapters/delivery_providers/cdek/test_client.py

@@ -324,6 +324,12 @@ adapter:
   cdek_retry_backoff_seconds: 0.1
   cdek_timeout_seconds: 7.5
   cdek_cache_ttl_seconds: 777
+
+observability:
+  enabled: false
+  service_name: "cdek-adapter-test-service"
+  otlp_endpoint: "http://collector:4317"
+  otlp_insecure: true
 """.strip(),
         encoding="utf-8",
     )

tests/config/fixtures/config.default.yaml

@@ -14,3 +14,9 @@ repository:
 adapter:
   cdek_client_id: "yaml-id"
   cdek_client_secret: "yaml-secret"
+
+observability:
+  enabled: false
+  service_name: "default-config-service"
+  otlp_endpoint: "http://default-collector:4317"
+  otlp_insecure: true

tests/config/fixtures/config.invalid_price_multiplier.yaml

@@ -22,3 +22,9 @@ adapter:
   cdek_retry_backoff_seconds: 0.2
   cdek_timeout_seconds: 10.0
   cdek_cache_ttl_seconds: 900
+
+observability:
+  enabled: false
+  service_name: "invalid-price-multiplier-service"
+  otlp_endpoint: "http://collector:4317"
+  otlp_insecure: true

tests/config/fixtures/config.missing_adapter.yaml

@@ -11,3 +11,9 @@ business_logic:
 repository:
   redis_dsn: "redis://localhost:6379/0"
   price_cache_ttl_seconds: 900
+
+observability:
+  enabled: false
+  service_name: "missing-adapter-service"
+  otlp_endpoint: "http://collector:4317"
+  otlp_insecure: true

tests/config/fixtures/config.missing_observability.yaml

@@ -0,0 +1,24 @@
+controller:
+  api_prefix: "/api/v1"
+  request_id_header: "X-Request-ID"
+
+service:
+  provider_timeout_seconds: 10.0
+  max_parallel_providers: 8
+
+business_logic:
+  weight_round_scale: 2
+  provider_price_multiplier: 1.0
+
+repository:
+  redis_dsn: "redis://localhost:6379/0"
+  price_cache_ttl_seconds: 900
+
+adapter:
+  cdek_base_url: "https://api.cdek.ru/v2"
+  cdek_client_id: "test-client-id"
+  cdek_client_secret: "test-client-secret"
+  cdek_retry_attempts: 2
+  cdek_retry_backoff_seconds: 0.2
+  cdek_timeout_seconds: 10.0
+  cdek_cache_ttl_seconds: 900

tests/config/fixtures/config.missing_observability_endpoint.yaml

@@ -0,0 +1,29 @@
+controller:
+  api_prefix: "/api/v1"
+  request_id_header: "X-Request-ID"
+
+service:
+  provider_timeout_seconds: 10.0
+  max_parallel_providers: 8
+
+business_logic:
+  weight_round_scale: 2
+  provider_price_multiplier: 1.0
+
+repository:
+  redis_dsn: "redis://localhost:6379/0"
+  price_cache_ttl_seconds: 900
+
+adapter:
+  cdek_base_url: "https://api.cdek.ru/v2"
+  cdek_client_id: "test-client-id"
+  cdek_client_secret: "test-client-secret"
+  cdek_retry_attempts: 2
+  cdek_retry_backoff_seconds: 0.2
+  cdek_timeout_seconds: 10.0
+  cdek_cache_ttl_seconds: 900
+
+observability:
+  enabled: true
+  service_name: "g2s-aggregator"
+  otlp_insecure: true

tests/config/fixtures/config.missing_price_multiplier.yaml

@@ -21,3 +21,9 @@ adapter:
   cdek_retry_backoff_seconds: 0.2
   cdek_timeout_seconds: 10.0
   cdek_cache_ttl_seconds: 900
+
+observability:
+  enabled: false
+  service_name: "missing-price-multiplier-service"
+  otlp_endpoint: "http://collector:4317"
+  otlp_insecure: true

tests/config/fixtures/config.test.override.yaml

@@ -14,3 +14,9 @@ repository:
 adapter:
   cdek_client_id: "test-id"
   cdek_client_secret: "test-secret"
+
+observability:
+  enabled: true
+  service_name: "override-config-service"
+  otlp_endpoint: "http://override-collector:4317"
+  otlp_insecure: false

tests/config/test_config_sections.py

@@ -24,6 +24,16 @@ INVALID_PRICE_MULTIPLIER_CONFIG_FILE = (
 MISSING_PRICE_MULTIPLIER_CONFIG_FILE = (
     PROJECT_ROOT / "tests" / "config" / "fixtures" / "config.missing_price_multiplier.yaml"
 )
+MISSING_OBSERVABILITY_CONFIG_FILE = (
+    PROJECT_ROOT / "tests" / "config" / "fixtures" / "config.missing_observability.yaml"
+)
+MISSING_OBSERVABILITY_ENDPOINT_CONFIG_FILE = (
+    PROJECT_ROOT
+    / "tests"
+    / "config"
+    / "fixtures"
+    / "config.missing_observability_endpoint.yaml"
+)
 
 
 def _use_runtime_config_files(
@@ -64,6 +74,10 @@ def test_configuration_sections_are_loaded_from_yaml_file(
     assert settings.adapter.cdek_retry_backoff_seconds == 0.2
     assert settings.adapter.cdek_timeout_seconds == 10.0
     assert settings.adapter.cdek_cache_ttl_seconds == 900
+    assert settings.observability.enabled is False
+    assert settings.observability.service_name == "g2s-aggregator-test"
+    assert settings.observability.otlp_endpoint == "http://localhost:4317"
+    assert settings.observability.otlp_insecure is True
 
 
 def test_get_settings_fails_when_required_yaml_section_is_missing(
@@ -91,6 +105,7 @@ def test_get_settings_returns_cached_instance(monkeypatch: pytest.MonkeyPatch) -
     assert first is second
     assert first.service.provider_timeout_seconds == 10.0
     assert first.business_logic.provider_price_multiplier == Decimal("1.0")
+    assert first.observability.service_name == "g2s-aggregator-test"
     get_settings.cache_clear()
 
 
@@ -109,6 +124,10 @@ def test_get_settings_uses_config_test_yaml_in_pytest_environment(
     assert settings.controller.api_prefix == "/from-config-test-yaml"
     assert settings.business_logic.provider_price_multiplier == Decimal("1.25")
     assert settings.adapter.cdek_client_id == "test-id"
+    assert settings.observability.enabled is True
+    assert settings.observability.service_name == "override-config-service"
+    assert settings.observability.otlp_endpoint == "http://override-collector:4317"
+    assert settings.observability.otlp_insecure is False
     get_settings.cache_clear()
 
 
@@ -142,3 +161,35 @@ def test_get_settings_fails_when_provider_price_multiplier_is_missing(
     locations = {tuple(item["loc"]) for item in error.value.errors()}
     assert ("business_logic", "provider_price_multiplier") in locations
     get_settings.cache_clear()
+
+
+def test_get_settings_fails_when_observability_section_is_missing(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    _use_runtime_config_files(
+        monkeypatch,
+        test_config_file=MISSING_OBSERVABILITY_CONFIG_FILE,
+    )
+
+    with pytest.raises(ValidationError) as error:
+        get_settings()
+
+    locations = {tuple(item["loc"]) for item in error.value.errors()}
+    assert ("observability",) in locations
+    get_settings.cache_clear()
+
+
+def test_get_settings_fails_when_observability_endpoint_is_missing(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    _use_runtime_config_files(
+        monkeypatch,
+        test_config_file=MISSING_OBSERVABILITY_ENDPOINT_CONFIG_FILE,
+    )
+
+    with pytest.raises(ValidationError) as error:
+        get_settings()
+
+    locations = {tuple(item["loc"]) for item in error.value.errors()}
+    assert ("observability", "otlp_endpoint") in locations
+    get_settings.cache_clear()

tests/repositories/cache/test_redis_cache.py

@@ -178,6 +178,12 @@ adapter:
   cdek_retry_backoff_seconds: 0.2
   cdek_timeout_seconds: 10.0
   cdek_cache_ttl_seconds: 900
+
+observability:
+  enabled: false
+  service_name: "repository-test-service"
+  otlp_endpoint: "http://collector:4317"
+  otlp_insecure: true
 """.strip(),
         encoding="utf-8",
     )

tests/smoke/test_app_import.py

@@ -7,6 +7,7 @@ from fastapi import FastAPI
 from app import config as config_module
 from app.config import Settings, get_settings
 from app.runtime import logging as logging_module
+from app.runtime import tracing as tracing_module
 
 TEST_CONFIG_FILE = Path(__file__).resolve().parents[2] / "config.test.yaml"
 
@@ -19,27 +20,40 @@ def _import_main_module(monkeypatch):
 
 
 def test_app_import_smoke(monkeypatch) -> None:
-    bootstrap_calls: list[None] = []
+    logging_bootstrap_calls: list[None] = []
+    tracing_bootstrap_calls: list[tuple[FastAPI, object]] = []
 
     def fake_configure_logging() -> None:
-        bootstrap_calls.append(None)
+        logging_bootstrap_calls.append(None)
+
+    def fake_configure_tracing(app: FastAPI, observability: object) -> None:
+        tracing_bootstrap_calls.append((app, observability))
 
     monkeypatch.setattr(logging_module, "configure_logging", fake_configure_logging)
+    monkeypatch.setattr(tracing_module, "configure_tracing", fake_configure_tracing)
     main_module = _import_main_module(monkeypatch)
 
     assert isinstance(main_module.app, FastAPI)
     assert isinstance(main_module.app.state.settings, Settings)
-    assert bootstrap_calls == [None]
+    assert logging_bootstrap_calls == [None]
+    assert tracing_bootstrap_calls == [
+        (main_module.app, main_module.app.state.settings.observability)
+    ]
     get_settings.cache_clear()
 
 
 def test_app_created_with_provided_settings(monkeypatch) -> None:
-    bootstrap_calls: list[None] = []
+    logging_bootstrap_calls: list[None] = []
+    tracing_bootstrap_calls: list[tuple[FastAPI, object]] = []
 
     def fake_configure_logging() -> None:
-        bootstrap_calls.append(None)
+        logging_bootstrap_calls.append(None)
+
+    def fake_configure_tracing(app: FastAPI, observability: object) -> None:
+        tracing_bootstrap_calls.append((app, observability))
 
     monkeypatch.setattr(logging_module, "configure_logging", fake_configure_logging)
+    monkeypatch.setattr(tracing_module, "configure_tracing", fake_configure_tracing)
     main_module = _import_main_module(monkeypatch)
     monkeypatch.setattr(config_module, "TEST_CONFIG_FILE", str(TEST_CONFIG_FILE))
 
@@ -47,5 +61,9 @@ def test_app_created_with_provided_settings(monkeypatch) -> None:
     instance = main_module.create_app(settings=settings)
 
     assert instance.state.settings is settings
-    assert bootstrap_calls == [None, None]
+    assert logging_bootstrap_calls == [None, None]
+    assert tracing_bootstrap_calls == [
+        (main_module.app, main_module.app.state.settings.observability),
+        (instance, settings.observability),
+    ]
     get_settings.cache_clear()

tests/tracing/test_bootstrap.py

@@ -0,0 +1,185 @@
+import importlib
+
+from fastapi import FastAPI
+
+from app.config import ObservabilityConfig
+
+
+def _reload_tracing_module():
+    tracing_module = importlib.import_module("app.runtime.tracing")
+    return importlib.reload(tracing_module)
+
+
+def _make_observability_config(**overrides) -> ObservabilityConfig:
+    payload = {
+        "enabled": True,
+        "service_name": "delivery-aggregator",
+        "otlp_endpoint": "http://collector:4317",
+        "otlp_insecure": True,
+    }
+    payload.update(overrides)
+    return ObservabilityConfig(**payload)
+
+
+def test_configure_tracing_skips_bootstrap_when_disabled(monkeypatch) -> None:
+    tracing_module = _reload_tracing_module()
+    calls = {"provider": 0, "fastapi": 0, "httpx": 0, "redis": 0}
+
+    def fake_get_or_create_tracer_provider(_observability):
+        calls["provider"] += 1
+        return object()
+
+    def fake_instrument_fastapi_app(_app, *, tracer_provider) -> None:
+        del tracer_provider
+        calls["fastapi"] += 1
+
+    def fake_instrument_httpx(*, tracer_provider) -> None:
+        del tracer_provider
+        calls["httpx"] += 1
+
+    def fake_instrument_redis(*, tracer_provider) -> None:
+        del tracer_provider
+        calls["redis"] += 1
+
+    monkeypatch.setattr(
+        tracing_module,
+        "_get_or_create_tracer_provider",
+        fake_get_or_create_tracer_provider,
+    )
+    monkeypatch.setattr(
+        tracing_module,
+        "_instrument_fastapi_app",
+        fake_instrument_fastapi_app,
+    )
+    monkeypatch.setattr(tracing_module, "_instrument_httpx", fake_instrument_httpx)
+    monkeypatch.setattr(tracing_module, "_instrument_redis", fake_instrument_redis)
+
+    tracing_module.configure_tracing(
+        FastAPI(),
+        _make_observability_config(enabled=False),
+    )
+
+    assert calls == {"provider": 0, "fastapi": 0, "httpx": 0, "redis": 0}
+
+
+def test_build_tracer_provider_uses_otlp_exporter_and_service_name(monkeypatch) -> None:
+    tracing_module = _reload_tracing_module()
+    created: dict[str, object] = {}
+
+    class FakeExporter:
+        def __init__(self, *, endpoint: str, insecure: bool) -> None:
+            created["endpoint"] = endpoint
+            created["insecure"] = insecure
+
+    class FakeBatchSpanProcessor:
+        def __init__(self, exporter: object) -> None:
+            self.exporter = exporter
+            created["processor_exporter"] = exporter
+
+    class FakeTracerProvider:
+        def __init__(self, *, resource) -> None:
+            self.resource = resource
+            self.span_processors: list[object] = []
+
+        def add_span_processor(self, processor: object) -> None:
+            self.span_processors.append(processor)
+
+    monkeypatch.setattr(tracing_module, "OTLPSpanExporter", FakeExporter)
+    monkeypatch.setattr(tracing_module, "BatchSpanProcessor", FakeBatchSpanProcessor)
+    monkeypatch.setattr(tracing_module, "TracerProvider", FakeTracerProvider)
+
+    provider = tracing_module._build_tracer_provider(
+        _make_observability_config(
+            service_name="g2s-aggregator",
+            otlp_endpoint="http://trace-backend:4317",
+            otlp_insecure=False,
+        )
+    )
+
+    assert created["endpoint"] == "http://trace-backend:4317"
+    assert created["insecure"] is False
+    assert provider.resource.attributes["service.name"] == "g2s-aggregator"
+    assert len(provider.span_processors) == 1
+    assert created["processor_exporter"] is provider.span_processors[0].exporter
+
+
+def test_configure_tracing_reuses_provider_and_global_instrumentation(monkeypatch) -> None:
+    tracing_module = _reload_tracing_module()
+    created = {
+        "exporters": 0,
+        "providers": 0,
+        "set_provider_calls": 0,
+        "fastapi_apps": [],
+        "httpx_calls": 0,
+        "redis_calls": 0,
+    }
+
+    class FakeExporter:
+        def __init__(self, *, endpoint: str, insecure: bool) -> None:
+            created["exporters"] += 1
+            self.endpoint = endpoint
+            self.insecure = insecure
+
+    class FakeBatchSpanProcessor:
+        def __init__(self, exporter: object) -> None:
+            self.exporter = exporter
+
+    class FakeTracerProvider:
+        def __init__(self, *, resource) -> None:
+            created["providers"] += 1
+            self.resource = resource
+            self.span_processors: list[object] = []
+
+        def add_span_processor(self, processor: object) -> None:
+            self.span_processors.append(processor)
+
+    class FakeInstrumentor:
+        def __init__(self, kind: str) -> None:
+            self.kind = kind
+            self.is_instrumented_by_opentelemetry = False
+
+        def instrument(self, **kwargs) -> None:
+            assert kwargs["tracer_provider"] is not None
+            created[f"{self.kind}_calls"] += 1
+            self.is_instrumented_by_opentelemetry = True
+
+    class FakeFastAPIInstrumentor:
+        @staticmethod
+        def instrument_app(app: FastAPI, *, tracer_provider) -> None:
+            assert tracer_provider is not None
+            created["fastapi_apps"].append(app)
+            app._is_instrumented_by_opentelemetry = True
+
+    def fake_set_tracer_provider(_provider: object) -> None:
+        created["set_provider_calls"] += 1
+
+    monkeypatch.setattr(tracing_module, "OTLPSpanExporter", FakeExporter)
+    monkeypatch.setattr(tracing_module, "BatchSpanProcessor", FakeBatchSpanProcessor)
+    monkeypatch.setattr(tracing_module, "TracerProvider", FakeTracerProvider)
+    monkeypatch.setattr(
+        tracing_module,
+        "_HTTPX_INSTRUMENTOR",
+        FakeInstrumentor("httpx"),
+    )
+    monkeypatch.setattr(
+        tracing_module,
+        "_REDIS_INSTRUMENTOR",
+        FakeInstrumentor("redis"),
+    )
+    monkeypatch.setattr(tracing_module, "FastAPIInstrumentor", FakeFastAPIInstrumentor)
+    monkeypatch.setattr(tracing_module.trace, "set_tracer_provider", fake_set_tracer_provider)
+
+    app_one = FastAPI()
+    app_two = FastAPI()
+    observability = _make_observability_config()
+
+    tracing_module.configure_tracing(app_one, observability)
+    tracing_module.configure_tracing(app_one, observability)
+    tracing_module.configure_tracing(app_two, observability)
+
+    assert created["exporters"] == 1
+    assert created["providers"] == 1
+    assert created["set_provider_calls"] == 1
+    assert created["fastapi_apps"] == [app_one, app_two]
+    assert created["httpx_calls"] == 1
+    assert created["redis_calls"] == 1