Backend Event ID Registry

Centralized reference of all [LoggerMessage] event IDs used across the backend API.
Prevents ID collisions and enables efficient log querying in Azure Application Insights.

Event ID Scheme

Event IDs follow the pattern XXX_YZZ where:

• XXX = Layer/domain prefix
• Y = Sub-category within the layer
• ZZ = Sequential event number

Registry by Project

Common — Key Vault and Configuration Loading (src/Common/Log.cs)

Event ID	Level	Message	Method
0	Critical	Option missing from config AND Key Vault	LogOptionValueIsCompletelyMissing
1	Information	Option loaded from Key Vault	LogOptionValueFromKeyVault
2	Information	Option loaded from configuration file	LogOptionValueFromConfiguration

Common — Configuration Proxy (src/Common/Log.cs)

Event ID	Level	Message	Method
410_103	Information	Config and features refreshed from proxy	LogRefreshSucceeded
410_104	Warning	Config refresh failed, retrying	LogRefreshFailed
410_105	Warning	Config refresh returned no values	LogBootstrapMissing
410_107	Information	Feature snapshot cache updated	LogFeatureSnapshotUpdated
410_201	Warning	exp returned HTTP error for config key	LogConfigKeyHttpError
410_202	Error	Network error fetching config key	LogConfigKeyNetworkError
410_203	Error	Timeout fetching config key	LogConfigKeyTimeout
410_204	Error	Deserialization error for config key	LogConfigKeyDeserializationError

Core (src/Core/Log.cs)

Event ID	Level	Message	Method
500_100	Information	General domain config started	LogGeneralDomainConfigurationStarted
500_101	Information	General domain config completed	LogGeneralDomainConfigurationCompleted
500_102	Information	Proxy config fetch started	LogProxyConfigurationFetchStarted
500_103	Information	Proxy config fetch completed	LogProxyConfigurationFetchCompleted
500_104	Error	Proxy config fetch failed	LogProxyConfigurationFetchFailed
500_105	Information	OTel configured	LogOTelConfigured
500_106	Information	Invoices domain configured	LogInvoicesDomainConfigured
500_107	Information	Application started	LogApplicationStarted
500_200	Information	Pipeline config started	LogPipelineConfigurationStarted
500_201	Information	Pipeline config completed	LogPipelineConfigurationCompleted
500_202	Debug	Security headers injected	LogSecurityHeadersInjected
500_203	Information	Swagger configured	LogSwaggerConfigured
500_300	Information	Health checks registered	LogHealthChecksRegistered
500_301	Debug	Health check completed	LogHealthCheckCompleted

Core.Auth (src/Core.Auth/Log.cs)

Event ID	Level	Message	Method
600_100	Information	User logged out	LogUserLoggedOut
600_101	Warning	Logout failed — null body	LogLogoutFailed
600_102	Information	Auth endpoints mapped	LogAuthEndpointsMapped
600_200	Warning	JWT secret missing	LogJwtSecretMissing
600_201	Warning	JWT issuer validation failed	LogJwtIssuerValidationFailed
600_202	Warning	JWT audience validation failed	LogJwtAudienceValidationFailed
600_203	Debug	JWT issuer fallback applied	LogJwtIssuerFallback
600_204	Debug	JWT audience fallback applied	LogJwtAudienceFallback
600_300	Information	Auth services configured	LogAuthServicesConfigured
600_301	Information	Auth middleware applied	LogAuthMiddlewareApplied
600_302	Error	AuthDbContext config failed	LogAuthDbContextConfigurationFailed

Invoices (src/Invoices/Modules/Log.cs)

Foundation Services (100_xxx)

Event ID	Level	Message	Method
100_100	Error	Invoice analysis validation exception	LogInvoiceAnalysisValidationException
100_101	Error	Invoice analysis dependency exception	LogInvoiceAnalysisDependencyException
100_102	Error	Invoice analysis dependency validation exception	LogInvoiceAnalysisDependencyValidationException
100_103	Error	Invoice analysis service exception	LogInvoiceAnalysisServiceException
100_104	Warning	No analysis performed on invoice	LogInvoiceAnalysisNoAnalysisHasBeenPerformed
100_200	Error	Invoice storage validation exception	LogInvoiceStorageValidationException
100_201	Error	Invoice storage dependency exception	LogInvoiceStorageDependencyException
100_202	Error	Invoice storage dependency validation exception	LogInvoiceStorageDependencyValidationException
100_203	Error	Invoice storage service exception	LogInvoiceStorageServiceException
100_300	Error	Merchant storage validation exception	LogMerchantStorageServiceValidationException
100_301	Error	Merchant storage dependency exception	LogMerchantStorageServiceDependencyException
100_302	Error	Merchant storage dependency validation exception	LogMerchantStorageServiceDependencyValidationException
100_303	Error	Merchant storage service exception	LogMerchantStorageServiceException

Orchestration Services (200_xxx)

Event ID	Level	Message	Method
200_100	Error	Invoice orchestration validation exception	LogInvoiceOrchestrationValidationException
200_101	Error	Invoice orchestration dependency exception	LogInvoiceOrchestrationDependencyException
200_102	Error	Invoice orchestration dependency validation exception	LogInvoiceOrchestrationDependencyValidationException
200_103	Error	Invoice orchestration service exception	LogInvoiceOrchestrationServiceException
200_200	Error	Merchant orchestration validation exception	LogMerchantOrchestrationValidationException
200_201	Error	Merchant orchestration dependency exception	LogMerchantOrchestrationDependencyException
200_202	Error	Merchant orchestration dependency validation exception	LogMerchantOrchestrationDependencyValidationException
200_203	Error	Merchant orchestration service exception	LogMerchantOrchestrationServiceException

Processing Services (300_xxx)

Event ID	Level	Message	Method
300_100	Error	Invoice processing validation exception	LogInvoiceProcessingValidationException
300_101	Error	Invoice processing dependency exception	LogInvoiceProcessingDependencyException
300_102	Error	Invoice processing dependency validation exception	LogInvoiceProcessingDependencyValidationException
300_103	Error	Invoice processing service exception	LogInvoiceProcessingServiceException

Classifier Broker (400_xxx)

Event ID	Level	Message	Method
400_100	Error	GPT method failed	LogGptMethodFailed
400_101	Error	GPT method failed with context	LogGptMethodFailedWithContext
400_102	Warning	Content filter triggered	LogContentFilterTriggered
400_103	Warning	Content filter triggered with context	LogContentFilterTriggeredWithContext
400_104	Information	GPT analysis started	LogGptAnalysisStarted
400_105	Warning	Allergen hallucination skipped	LogAllergenHallucinationSkipped
400_106	Warning	Allergen unrecognized skipped	LogAllergenUnrecognizedSkipped

General Validation (900_xxx)

Event ID	Level	Message	Method
900_100	Warning	User identifier not set	LogUserIdentifierNotSetWarning

ID Range Allocation

Range	Project	Domain
0–99	Common/Telemetry	OTel setup, Key Vault config
100_000–199_999	Invoices	Foundation services
200_000–299_999	Invoices	Orchestration services
300_000–399_999	Invoices	Processing services
400_000–409_999	Invoices	Classifier/AI broker
410_000–419_999	Common/Config	Configuration proxy
500_000–599_999	Core	Startup, middleware, health
600_000–699_999	Core.Auth	Auth, JWT, identity
900_000–999_999	Invoices	General validation

Custom Metrics Registry

Invoice Meter (arolariu.Backend.Domain.Invoices) — RED Method

Instrument	Type	Unit	Tags	Description
invoices.operations	Counter	operations	operation, entity, outcome, failure.reason	Invoice/merchant CRUD rate with outcome
invoices.operations.duration	Histogram	ms	operation, entity, outcome	CRUD operation latency distribution
invoices.analysis	Counter	analyses	outcome, failure.reason	Analysis pipeline rate with outcome
invoices.analysis.duration	Histogram	ms	outcome	Analysis pipeline latency distribution
invoices.analysis.content_filter.triggered	Counter	events	—	AI content filter triggers
invoices.cosmosdb.request_charge	Histogram	RU	db.operation, db.cosmosdb.container	Cosmos DB RU per operation

SLA/QoS Computation (KQL):

// Success Rate SLI (per operation)
customMetrics
| where name == "invoices.operations"
| summarize total=sum(value), success=sumif(value, customDimensions["outcome"]=="success")
  by tostring(customDimensions["operation"]), tostring(customDimensions["entity"])
| extend success_rate = round(100.0 * success / total, 2)
| order by success_rate asc

// Latency SLO (p99 < threshold)
customMetrics
| where name == "invoices.operations.duration"
| where customDimensions["outcome"] == "success"
| summarize p50=percentile(value, 50), p95=percentile(value, 95), p99=percentile(value, 99)
  by tostring(customDimensions["operation"]), tostring(customDimensions["entity"])

// Error Budget Burn Rate
customMetrics
| where name == "invoices.operations"
| where customDimensions["outcome"] == "failure"
| summarize failures=sum(value) by bin(timestamp, 1h), tostring(customDimensions["failure.reason"])
| render timechart

Auth Meter (arolariu.Backend.Auth)

Instrument	Type	Unit	Description
auth.logouts	Counter	events	Successful logouts
auth.logout_failures	Counter	events	Failed logout attempts
auth.jwt.validation_failures	Counter	events	JWT validation failures (tag: reason)

Common Meter (arolariu.Backend.Common)

Instrument	Type	Unit	Description
config.refresh.success	Counter	events	Config refresh successes
config.refresh.failure	Counter	events	Config refresh failures
config.refresh.duration	Histogram	ms	Config refresh cycle duration