[rrohitramsen]

Fixes the SDK setup problems found by verifying the documented setups against the published 0.3.x packages: only Spring Boot worked as documented. After this PR, every SDK reads the same agenttel.yml and puts topology, baselines and decision attributes on HTTP server spans.

What changed

One config format, shared by all SDKs. Python, Node and Go now read the Spring Boot format:

• an agenttel: root and kebab-case keys
• operations as a map keyed by "METHOD /route"; "[POST /x]" and POST /x are the same key, and :id matches {id}
• latencies such as "45ms", or a plain number of milliseconds
• profiles for shared decision defaults

Each SDK's old format still loads and logs a deprecation warning.

Python

• FastAPI server spans now get baselines and decisions.
• instrument_fastapi() reuses the app's existing TracerProvider instead of replacing it, adds topology to its resource, and instruments the app.
• Decision attributes now use the attributes.json names: agenttel.decision.* (previously agenttel.operation.*) and topology.on_call_channel (previously oncall_channel). The old constant names remain as aliases.
• Fixed the FastAPI example.

Node

• The package now loads under plain Node 18, 20 and 22, as ESM and as CommonJS. Relative imports carry .js extensions (built with NodeNext), and dist/cjs is marked as CommonJS.
• Express and Fastify middleware set decision attributes. Passing { engine } sets topology, baselines and decisions in one go.
• Added AgentTelEngine.fromConfigFile() and engine.resourceAttributes().
• The examples now register the span processor and HTTP instrumentation.

Go

• YAML operations now become static baselines and decisions in Build().
• Added WithEngine(engine) for the net/http, Gin and gRPC middleware.
• net/http records http.route from Go 1.22+ ServeMux patterns.
• Added engine.Resource().
• go-service-example and gin-example compile and run against the real API.
• The docs now give the real minimums: Go 1.24 and otel/sdk 1.39.0.

JVM javaagent

• Server spans now get baselines and decisions. They previously had no agenttel.* attributes, because the span is named POST until routing finishes.
• Bracketed keys work in the agent's YAML.
• Topology is added to the resource through a resource customizer.
• The root build no longer hard-codes version = "0.2.0-alpha". Maven coordinates were already correct; only jar names and javadoc titles were wrong.

Release prep

• Versions: Maven 0.4.0-alpha, npm 0.4.0-alpha.0, PyPI 0.4.0a1.
• CHANGELOG entry for 0.4.0-alpha.
• README and quick-start setup snippets fixed.

Testing

Each SDK has a new real-server integration test, like the Spring Boot EnrichmentTest: send one request, then assert topology, agenttel.baseline.latency_p50_ms=45 and agenttel.decision.retryable on the server span.

• Python: uvicorn and FastAPI.
• Node: Express and Fastify, run against the built package under plain node.
• Go: otelhttp with httptest.
• JVM: a plain Spring Boot app started with -javaagent:<built jar>.

Test suites:

• JVM: 326 tests pass.
• Python: 122 pass.
• Node: 89 pass.
• Go: all pass, including the GenAI submodules.

Install checks in fresh Docker containers:

• The Python wheel on 3.11 and 3.12.
• The npm tarball on Node 18, 20 and 22 (npm run test:pack).
• Go as a dependency of a separate module.
• Spring Boot and the javaagent against 0.4.0-alpha published to a local Maven repo.

Not included

• I haven't tested OpenTelemetry JS 2.x, so the Node peer range stays at ^1.25.0.
• The Go tag agenttel-go/v0.4.0-alpha exists locally but is not pushed. Push it when releasing.
• Publishing to Maven Central, npm and PyPI is still to do.