dd-trace-js

Use when adding, debugging, fixing, or modifying instrumentation and plugins for third-party libraries in dd-trace-js. Triggers: "add a new integration", "instrument a library", any *Plugin base class (Tracing/Database/Cache/ Client/Server/Consumer/Producer/Composite), "addHook", "shimmer.wrap", "orchestrion", "bindStart"/"bindFinish", "diagnostic channel", "runStores", "subscriber cardinality", "channel.publish gate", "read upstream source", "reference plugin".

Use when a dd-trace-js change introduces or substantially changes a class hierarchy, module boundary, shared helper layer, public API, or duplicated behavior across multiple types. Triggers: architecture decision, design review, refactor shared behavior, new abstraction, composition versus inheritance, expose internals, module coupling, public surface, hot-path architecture, score the design.

Use when classifying, investigating, or fixing a suspected flaky test, intermittent test result, nondeterministic CI test failure, timing race, hang, or test-order dependency in dd-trace-js. Classifies infrastructure and deterministic failures before reproduction or code search.

Use when adding, debugging, or modifying LLMObs plugins for an LLM library in dd-trace-js. Triggers: "add LLMObs support", "instrument chat completions / streaming / embeddings / agent runs / orchestration / tool calls / retrieval", "LLMObsPlugin", "getLLMObsSpanRegisterOptions", "setLLMObsTags", "SPAN_KINDS", "span kind", any provider tag ("openai" / "anthropic" / "genai" / "google" / "langchain" / "langgraph" / "ai" llmobs), "VCR cassettes".

Use when writing, modifying, or debugging tests for an LLMObs plugin in dd-trace-js. Triggers: "write LLMObs tests", "test an LLMObs plugin", "assertLlmObsSpanEvent", "useLlmObs", "getEvents", any MOCK_* matcher ("MOCK_STRING" / "MOCK_NOT_NULLISH" / "MOCK_NUMBER" / "MOCK_OBJECT"), "VCR cassette", "vcr proxy", "127.0.0.1:9126", "record a cassette", "test:llmobs:plugins".

Use when adding, modifying, debugging, or reviewing dd-trace-js serverless platform integrations that create root invocation spans for AWS Lambda, Azure Functions, Google Cloud Functions, or similar runtimes. Triggers: serverless integration, function invocation root span, Lambda runtime, Azure Functions, GCP Functions, type = 'serverless', DD_LAMBDA_HANDLER, datadog-lambda-js, deployed serverless verification, manual serverless test.