feat: add agent workflow metrics collection

Add comprehensive OpenTelemetry-based metrics for agent observability:

- Workflow completion/failure tracking with duration measurements
- Step execution counters for performance monitoring
- Tool usage tracking with normalized tool names
- Non-blocking telemetry emission with named async tasks
- Comprehensive unit and integration test coverage
- Graceful handling when telemetry is disabled

tests/unit/providers/agents/test_agent_metrics.py

@@ -0,0 +1,212 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+import asyncio
+from unittest.mock import AsyncMock, Mock
+
+import pytest
+from opentelemetry.trace import SpanContext, TraceFlags
+
+from llama_stack.providers.inline.agents.meta_reference.agent_instance import ChatAgent
+
+
+class FakeSpan:
+    def __init__(self, trace_id: int = 123, span_id: int = 456):
+        self._context = SpanContext(
+            trace_id=trace_id,
+            span_id=span_id,
+            is_remote=False,
+            trace_flags=TraceFlags(0x01),
+        )
+
+    def get_span_context(self):
+        return self._context
+
+
+@pytest.fixture
+def agent_with_telemetry():
+    """Create a real ChatAgent with telemetry API"""
+    telemetry_api = AsyncMock()
+
+    agent = ChatAgent(
+        agent_id="test-agent",
+        agent_config=Mock(),
+        inference_api=Mock(),
+        safety_api=Mock(),
+        tool_runtime_api=Mock(),
+        tool_groups_api=Mock(),
+        vector_io_api=Mock(),
+        telemetry_api=telemetry_api,
+        persistence_store=Mock(),
+        created_at="2025-01-01T00:00:00Z",
+        policy=[],
+    )
+    return agent
+
+
+@pytest.fixture
+def agent_without_telemetry():
+    """Create a real ChatAgent without telemetry API"""
+    agent = ChatAgent(
+        agent_id="test-agent",
+        agent_config=Mock(),
+        inference_api=Mock(),
+        safety_api=Mock(),
+        tool_runtime_api=Mock(),
+        tool_groups_api=Mock(),
+        vector_io_api=Mock(),
+        telemetry_api=None,
+        persistence_store=Mock(),
+        created_at="2025-01-01T00:00:00Z",
+        policy=[],
+    )
+    return agent
+
+
+class TestAgentMetrics:
+    def test_step_execution_metrics(self, agent_with_telemetry, monkeypatch):
+        """Test that step execution metrics are emitted correctly"""
+        fake_span = FakeSpan()
+        monkeypatch.setattr(
+            "llama_stack.providers.inline.agents.meta_reference.agent_instance.get_current_span", lambda: fake_span
+        )
+
+        # Capture the metric instead of actually creating async task
+        captured_metrics = []
+
+        async def capture_metric(metric):
+            captured_metrics.append(metric)
+
+        monkeypatch.setattr(agent_with_telemetry.telemetry_api, "log_event", capture_metric)
+
+        def mock_create_task(coro, *, name=None):
+            return asyncio.run(coro)
+
+        monkeypatch.setattr(
+            "llama_stack.providers.inline.agents.meta_reference.agent_instance.asyncio.create_task", mock_create_task
+        )
+
+        agent_with_telemetry._track_step()
+
+        assert len(captured_metrics) == 1
+        metric = captured_metrics[0]
+        assert metric.metric == "llama_stack_agent_steps_total"
+        assert metric.value == 1
+        assert metric.unit == "1"
+        assert metric.attributes["agent_id"] == "test-agent"
+
+    def test_workflow_completion_metrics(self, agent_with_telemetry, monkeypatch):
+        """Test that workflow completion metrics are emitted correctly"""
+        fake_span = FakeSpan()
+        monkeypatch.setattr(
+            "llama_stack.providers.inline.agents.meta_reference.agent_instance.get_current_span", lambda: fake_span
+        )
+
+        captured_metrics = []
+
+        async def capture_metric(metric):
+            captured_metrics.append(metric)
+
+        monkeypatch.setattr(agent_with_telemetry.telemetry_api, "log_event", capture_metric)
+
+        def mock_create_task(coro, *, name=None):
+            return asyncio.run(coro)
+
+        monkeypatch.setattr(
+            "llama_stack.providers.inline.agents.meta_reference.agent_instance.asyncio.create_task", mock_create_task
+        )
+
+        agent_with_telemetry._track_workflow("completed", 2.5)
+
+        assert len(captured_metrics) == 2
+
+        # Check workflow count metric
+        count_metric = captured_metrics[0]
+        assert count_metric.metric == "llama_stack_agent_workflows_total"
+        assert count_metric.value == 1
+        assert count_metric.attributes["status"] == "completed"
+
+        # Check duration metric
+        duration_metric = captured_metrics[1]
+        assert duration_metric.metric == "llama_stack_agent_workflow_duration_seconds"
+        assert duration_metric.value == 2.5
+        assert duration_metric.unit == "s"
+
+    def test_tool_usage_metrics(self, agent_with_telemetry, monkeypatch):
+        """Test that tool usage metrics are emitted correctly"""
+        fake_span = FakeSpan()
+        monkeypatch.setattr(
+            "llama_stack.providers.inline.agents.meta_reference.agent_instance.get_current_span", lambda: fake_span
+        )
+
+        captured_metrics = []
+
+        async def capture_metric(metric):
+            captured_metrics.append(metric)
+
+        monkeypatch.setattr(agent_with_telemetry.telemetry_api, "log_event", capture_metric)
+
+        def mock_create_task(coro, *, name=None):
+            return asyncio.run(coro)
+
+        monkeypatch.setattr(
+            "llama_stack.providers.inline.agents.meta_reference.agent_instance.asyncio.create_task", mock_create_task
+        )
+
+        agent_with_telemetry._track_tool("web_search")
+
+        assert len(captured_metrics) == 1
+        metric = captured_metrics[0]
+        assert metric.metric == "llama_stack_agent_tool_calls_total"
+        assert metric.attributes["tool"] == "web_search"
+
+    def test_knowledge_search_tool_mapping(self, agent_with_telemetry, monkeypatch):
+        """Test that knowledge_search tool is mapped to rag"""
+        fake_span = FakeSpan()
+        monkeypatch.setattr(
+            "llama_stack.providers.inline.agents.meta_reference.agent_instance.get_current_span", lambda: fake_span
+        )
+
+        captured_metrics = []
+
+        async def capture_metric(metric):
+            captured_metrics.append(metric)
+
+        monkeypatch.setattr(agent_with_telemetry.telemetry_api, "log_event", capture_metric)
+
+        def mock_create_task(coro, *, name=None):
+            return asyncio.run(coro)
+
+        monkeypatch.setattr(
+            "llama_stack.providers.inline.agents.meta_reference.agent_instance.asyncio.create_task", mock_create_task
+        )
+
+        agent_with_telemetry._track_tool("knowledge_search")
+
+        assert len(captured_metrics) == 1
+        metric = captured_metrics[0]
+        assert metric.attributes["tool"] == "rag"
+
+    def test_no_telemetry_api(self, agent_without_telemetry):
+        """Test that methods work gracefully when telemetry_api is None"""
+        # These should not crash
+        agent_without_telemetry._track_step()
+        agent_without_telemetry._track_workflow("failed", 1.0)
+        agent_without_telemetry._track_tool("web_search")
+
+    def test_no_active_span(self, agent_with_telemetry, monkeypatch):
+        """Test that methods work gracefully when no span is active"""
+        monkeypatch.setattr(
+            "llama_stack.providers.inline.agents.meta_reference.agent_instance.get_current_span", lambda: None
+        )
+
+        # These should not crash and should not call telemetry
+        agent_with_telemetry._track_step()
+        agent_with_telemetry._track_workflow("failed", 1.0)
+        agent_with_telemetry._track_tool("web_search")
+
+        # Telemetry should not have been called
+        agent_with_telemetry.telemetry_api.log_event.assert_not_called()