docs: add guide for integrating SDK with existing OpenTelemetry

docs/integrating-with-existing-opentelemetry.md

@@ -0,0 +1,150 @@
+# Integrating with existing OpenTelemetry
+
+This guide is for developers whose application **already** initializes OpenTelemetry — for example with `azure-monitor-opentelemetry`, an OTLP collector, or a vendor-specific exporter — and who want Agent 365 spans to flow alongside their existing telemetry. If you're starting fresh, see the [observability-core README](../libraries/microsoft-agents-a365-observability-core/README.md) for the standalone setup.
+
+## The integration rule
+
+> **Initialize your existing OpenTelemetry stack first, then call Agent 365's `configure()`.** The SDK detects the existing `TracerProvider` and adds its processors to it. Your existing backend receives every span; the Agent 365 backend also receives spans when `ENABLE_A365_OBSERVABILITY_EXPORTER=true` and a `token_resolver` is provided (otherwise `configure()` falls back to `ConsoleSpanExporter`).
+
+The detection happens in [`config.py`](../libraries/microsoft-agents-a365-observability-core/microsoft_agents_a365/observability/core/config.py): if a real (non-no-op) `TracerProvider` is already set (detected via a non-None `resource` attribute), `configure()` adds an `_EnrichingBatchSpanProcessor` (wrapping the configured exporter) and a custom `SpanProcessor` to that provider rather than creating a new one.
+
+## Two minimal patterns
+
+### Pattern A — `azure-monitor-opentelemetry`
+
+```python
+import os
+
+from azure.monitor.opentelemetry import configure_azure_monitor
+from microsoft_agents_a365.observability.core import configure
+
+# 1. Existing OTel: Azure Monitor sets up a TracerProvider + AM exporter.
+configure_azure_monitor(connection_string=os.environ["APPLICATIONINSIGHTS_CONNECTION_STRING"])
+
+# 2. Agent 365 attaches its processors to that same TracerProvider.
+configure(
+    service_name="my-agent",
+    service_namespace="my-namespace",
+    token_resolver=my_token_resolver,
+)
+```
+
+→ Runnable version: [`observability-with-azure-monitor`](https://github.com/microsoft/Agent365-Samples/tree/main/python/observability-with-azure-monitor) sample.
+
+### Pattern B — manual OTel SDK + OTLP exporter
+
+```python
+import os
+
+from opentelemetry import trace
+from opentelemetry.exporter.otlp.proto.http.trace_exporter import OTLPSpanExporter
+from opentelemetry.sdk.resources import SERVICE_NAME, Resource
+from opentelemetry.sdk.trace import TracerProvider
+from opentelemetry.sdk.trace.export import BatchSpanProcessor
+
+from microsoft_agents_a365.observability.core import configure
+
+# 1. Existing OTel: build provider + OTLP exporter explicitly.
+provider = TracerProvider(resource=Resource.create({SERVICE_NAME: "my-agent"}))
+provider.add_span_processor(
+    BatchSpanProcessor(OTLPSpanExporter(endpoint=os.environ["OTEL_EXPORTER_OTLP_ENDPOINT"]))
+)
+trace.set_tracer_provider(provider)
+
+# 2. Agent 365 attaches to that same provider.
+configure(
+    service_name="my-agent",
+    service_namespace="my-namespace",
+    token_resolver=my_token_resolver,
+)
+```
+
+→ Runnable version: [`observability-with-otlp`](https://github.com/microsoft/Agent365-Samples/tree/main/python/observability-with-otlp) sample (defaults to `ConsoleSpanExporter` for zero setup).
+
+## Auto-instrumentation vs. manual instrumentation
+
+The OTel **backend** (where spans go) and the **instrumentation style** (how spans are produced) are independent axes. You can mix them freely.
+
+|                          | Auto (extension package)                                          | Manual (`InvokeAgentScope` / `InferenceScope` / `ExecuteToolScope`) |
+|--------------------------|-------------------------------------------------------------------|--------------------------------------------------------------------|
+| **Azure Monitor**        | Demonstrated by `observability-with-azure-monitor` sample         | Same `configure()`; replace agent code with manual scope wrapping  |
+| **OTLP / vendor-neutral** | Same `configure()`; install your framework's extension package   | Demonstrated by `observability-with-otlp` sample                   |
+
+For auto-instrumentation, install the framework-specific extension package — for example:
+
+- OpenAI Agents SDK → `microsoft-agents-a365-observability-extensions-openai`
+- LangChain → `microsoft-agents-a365-observability-extensions-langchain`
+- Semantic Kernel → `microsoft-agents-a365-observability-extensions-semantickernel`
+- Microsoft Agent Framework → `microsoft-agents-a365-observability-extensions-agentframework`
+
+For the OpenAI Agents SDK extension, instantiate `OpenAIAgentsTraceInstrumentor()` and call `.instrument()` **after** `configure()`. The instrumentor raises `RuntimeError` if Agent 365 isn't configured first.
+
+## What spans should I expect to see?
+
+The SDK produces three core span kinds. Your backend should show them in this typical hierarchy:
+
+| `gen_ai.operation.name` | Produced by                                       | Typical parent | Span name (default) | Notes |
+|-------------------------|---------------------------------------------------|----------------|---------------------|-------|
+| `invoke_agent`          | `InvokeAgentScope` (one per user turn)            | (root or app)  | `invoke_agent <agent_name>` when set, else `invoke_agent` | |
+| (varies — see notes) | `InferenceScope` (one per LLM call) | `invoke_agent` | `<operation> <model>` | **Manual instrumentation** uses `InferenceOperationType.value` (currently `Chat` / `TextCompletion` / `GenerateContent`, capitalized). **Auto-instrumentation** (e.g. `OpenAIAgentsTraceInstrumentor`) uses lowercase per the [OTel GenAI semconv](https://opentelemetry.io/docs/specs/semconv/gen-ai/gen-ai-spans/) (e.g. `chat`). The two are inconsistent today. |
+| `execute_tool`          | `ExecuteToolScope` (one per tool invocation)      | `invoke_agent` | `execute_tool <tool_name>` (always includes the tool name) | Records tool name, args, and result. |
+
+Filter your backend by the `gen_ai.operation.name` attribute or by span name. Note that `inference` is *not* the literal attribute value — manual instrumentation produces `Chat` / `TextCompletion` / `GenerateContent` (the `InferenceOperationType.value`), while auto-instrumentation extension packages produce the lowercase OTel-spec form (e.g. `chat`). This casing discrepancy is tracked as an SDK issue.
+
+## Verifying the integration
+
+If you've called `configure()` but don't see Agent 365 spans in your backend, isolate the problem by adding a `ConsoleSpanExporter` temporarily:
+
+```python
+from opentelemetry import trace
+from opentelemetry.sdk.trace.export import BatchSpanProcessor, ConsoleSpanExporter
+
+# After configure() has run:
+trace.get_tracer_provider().add_span_processor(BatchSpanProcessor(ConsoleSpanExporter()))
+```
+
+Run a single turn. If you see `invoke_agent` / `Chat` (or `chat`) / `execute_tool` JSON dumps on stdout, the SDK is producing spans correctly — the issue is in your backend exporter (network, auth, sampling). If you don't see them, the integration itself is wrong; check the pitfalls below.
+
+## Common pitfalls
+
+### Pitfall 1: Calling `configure_azure_monitor()` after Agent 365 `configure()`
+
+**Symptom:** Agent 365 spans don't appear in any backend.
+
+**Cause:** `configure_azure_monitor` (and many vendor packages) replace the global `TracerProvider`. If they run *after* `configure()`, the provider with our processors is discarded.
+
+**Fix:** Always initialize Azure Monitor (or any OTel setup) **before** calling Agent 365 `configure()`.
+
+### Pitfall 2: Calling Agent 365 `configure()` before app's OTel setup
+
+**Symptom:** Same as above — Agent 365 spans are missing.
+
+**Cause:** `configure()` creates its own `TracerProvider` (no existing one detected). Your app's later OTel init replaces it, dropping our processors.
+
+**Fix:** Same as Pitfall 1 — OTel first, then Agent 365.
+
+### Pitfall 3: `OTEL_SDK_DISABLED=true` or `OTEL_TRACES_EXPORTER=none`
+
+**Symptom:** Nothing exports — neither your existing backend nor Agent 365.
+
+**Cause:** These environment variables disable OpenTelemetry SDK-wide. They suppress Agent 365 spans alongside everything else.
+
+**Fix:** Use sampling (`OTEL_TRACES_SAMPLER`) or per-exporter configuration instead of the global disable. If you intentionally want to disable tracing in a particular environment, that's fine — just understand it disables Agent 365 too.
+
+### Pitfall 4: `ENABLE_OBSERVABILITY` not set
+
+**Symptom:** Your existing OTel backend works (Azure Monitor / OTLP / etc. show spans), but Agent 365 scope blocks (`InvokeAgentScope`, `InferenceScope`, `ExecuteToolScope`) produce zero spans. No errors, no warnings.
+
+**Cause:** Agent 365's scope classes gate span creation on the `ENABLE_OBSERVABILITY` (or `ENABLE_A365_OBSERVABILITY`) environment variable. If neither is set to `true` / `1` / `yes` / `on`, every scope's `__init__` skips span creation entirely. This is **independent** of OTel's own enable/disable mechanism — your existing OTel telemetry continues to flow normally.
+
+**Fix:** Set `ENABLE_OBSERVABILITY=true` (or `ENABLE_A365_OBSERVABILITY=true`) in your environment before creating any scopes / emitting spans (the check happens at scope construction time, not import time). Both runnable samples include this in their `.env.template`.
+
+## Exporter combinations
+
+| Combination                             | What's installed                                                          | What to call                                                              | Gotchas                                                                                       |
+|-----------------------------------------|---------------------------------------------------------------------------|---------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------|
+| Azure Monitor only                      | `azure-monitor-opentelemetry`                                             | `configure_azure_monitor(...)`                                            | Standard Azure Monitor — no Agent 365 spans flow.                                             |
+| Azure Monitor + Agent 365               | `azure-monitor-opentelemetry`, `microsoft-agents-a365-observability-core` | `configure_azure_monitor(...)` then `configure(...)`                      | Order matters (see Pitfall 1).                                                                |
+| OTLP collector + Agent 365              | `opentelemetry-sdk`, `opentelemetry-exporter-otlp-*`, A365 core           | Build provider + `BatchSpanProcessor(OTLPSpanExporter(...))` then `configure(...)` | Set `OTEL_EXPORTER_OTLP_ENDPOINT`; collector must be reachable.                          |
+| Agent 365 only                          | `microsoft-agents-a365-observability-core`                                | `configure(...)` only                                                     | SDK creates its own `TracerProvider`; spans go to Agent 365 backend only.                     |
+| OTLP + Azure Monitor + Agent 365        | All of the above                                                          | Configure Azure Monitor first; add OTLP `BatchSpanProcessor` to the provider; call `configure(...)` | All three exporters receive every span. Watch out for duplicate processors if Azure Monitor itself adds OTLP. |

libraries/microsoft-agents-a365-observability-core/README.md

@@ -5,6 +5,8 @@
 
 Telemetry, tracing, and monitoring components for AI agents built on OpenTelemetry. This package provides structured spans for agent invocation, tool execution, and LLM inference with context propagation and pluggable exporters.
 
+> **Already using OpenTelemetry?** This SDK detects an existing `TracerProvider` and adds its processors to it — your spans flow to your existing backend (Azure Monitor, OTLP collector, vendor exporter, etc.) and, when `ENABLE_A365_OBSERVABILITY_EXPORTER` is enabled with a configured `token_resolver`, also to the Agent 365 backend. See [Integrating with existing OpenTelemetry](../../docs/integrating-with-existing-opentelemetry.md) for setup patterns and troubleshooting.
+
 ## Installation
 
 ```bash