title: Observability Examples description: Workflow examples for observability in Loopstack — quota tracking, custom tool interceptors for tracing, custom quota calculators, and event-driven audit logging

@loopstack/observability-examples

Observability workflow examples for the Loopstack automation framework.

Workflow examples for tracking and enforcing operational limits.

Install as Source (Recommended)

npx giget@latest gh:loopstack-ai/loopstack/registry/examples/observability-examples src/observability-examples

Register the module:

import { Module } from '@nestjs/common';
import { LoopstackModule } from '@loopstack/loopstack-module';
import { ObservabilityExamplesModule } from './observability-examples/observability-examples.module';

@Module({
  imports: [LoopstackModule.forRoot(), ObservabilityExamplesModule],
})
export class AppModule {}

Install as a Dependency

npm install @loopstack/observability-examples

import { ObservabilityExamplesModule } from '@loopstack/observability-examples';

Examples

| Example | Studio title | Description | | --------------------------------------------------- | ------------------------------------------------- | --------------------------------------------------------------------------------- | | Quota | Observability - Quota Example | Manual check + report usage with @loopstack/quota, Redis-backed when enabled | | Tracing Interceptor | Observability - Tracing Interceptor Example | Custom ToolInterceptor measuring every tool execution app-wide | | Custom Quota Calculator | Observability - Custom Quota Calculator Example | Custom ToolQuotaCalculator metering a tool automatically via QuotaInterceptor | | Audit Log | Observability - Audit Log Example | @OnEvent listener recording workflow & document lifecycle events |

Quota

Demonstrates the manual quota API of @loopstack/quota:

1. quotaClient.checkQuota(userId, quotaType) — verify available budget
2. Perform the (placeholder) operation if allowed
3. quotaClient.report(userId, quotaType, amount) — charge against the quota

When QuotaModule.forRoot({ enabled: false }), both calls no-op. Set enabled: true plus Redis connection options to enforce real limits. Note: with quota enabled, a user without a limit key in Redis is blocked by default.

Built-in quota types: llm-cost (LLM token cost in microcents) and processing-time-ms (tool execution time).

Files

• quota-example.workflow.ts — workflow class

Tracing Interceptor

Demonstrates writing a custom ToolInterceptor:

• @UseToolInterceptor({ priority: 10 }) registers the class app-wide — the framework discovers it via NestJS DiscoveryService, no manual wiring
• The interceptor wraps every tool call (all modules), measures duration, and records entries in an injectable ToolTraceService
• The workflow runs a few SimulateWorkTool calls, then filters the trace by its own workflowId and renders a markdown table

Interceptors follow a chain pattern like NestJS interceptors: run logic before/after next(), transform results, short-circuit (caching), or catch errors. Lower priority runs first (outermost).

Files

• tracing-example.workflow.ts — workflow class
• interceptors/tracing.interceptor.ts — the custom ToolInterceptor
• services/tool-trace.service.ts — injectable trace store
• tools/simulate-work.tool.ts — demo tool that sleeps for a configurable duration

Custom Quota Calculator

Demonstrates extending the quota system with a custom ToolQuotaCalculator:

• WordsProcessedQuotaCalculator defines quota type words-processed and derives the charged amount from the tool result (word count)
• The module registers it for AnalyzeTextTool in onModuleInit via QuotaCalculatorRegistry
• The built-in QuotaInterceptor then checks the quota before and reports usage after every AnalyzeTextTool execution — the workflow just calls the tool, no manual check/report

This is the recommended pattern for metering tools: the workflow stays clean, enforcement lives in the interceptor.

Files

• custom-calculator-example.workflow.ts — workflow class
• calculators/words-processed.calculator.ts — the custom ToolQuotaCalculator
• tools/analyze-text.tool.ts — demo tool whose usage is metered

Audit Log

Demonstrates subscribing to framework events for monitoring:

• The framework dispatches lifecycle events on the client.message channel — e.g. workflow.created, workflow.updated, document.created
• AuditListener uses @OnEvent('client.message') to capture every event into an injectable AuditLogService (bounded in-memory store)
• The workflow saves a few documents to generate events, then renders its own audit trail filtered by workflowId

This is the event-driven counterpart to the tracing interceptor: interceptors wrap tool calls, event listeners observe workflow and document lifecycle. Swap the in-memory store for a database or metrics exporter in production.

Files

• audit-log-example.workflow.ts — workflow class
• listeners/audit.listener.ts — the @OnEvent listener
• services/audit-log.service.ts — injectable audit store

About

Author: Jakob Klippel

License: MIT