fix: resolve telemetry handler warnings

- Add try-rescue blocks around telemetry.attach_many calls
- Handle case where telemetry app not yet started gracefully
- Add explicit telemetry dependency to mix.exs
- Fixes 'Failed to lookup telemetry handlers' warnings

Author: azmaveth

lib/ex_llm/infrastructure/circuit_breaker/metrics.ex

@@ -490,12 +490,18 @@ defmodule ExLLM.Infrastructure.CircuitBreaker.Metrics do
       [:ex_llm, :circuit_breaker, :health_check, :completed]
     ]
 
-    :telemetry.attach_many(
-      "circuit_breaker_metrics_handler",
-      events,
-      &handle_telemetry_event/4,
-      %{}
-    )
+    try do
+      :telemetry.attach_many(
+        "circuit_breaker_metrics_handler",
+        events,
+        &handle_telemetry_event/4,
+        %{}
+      )
+    rescue
+      ArgumentError ->
+        # Telemetry application not started yet, ignore
+        :ok
+    end
   end
 
   defp handle_telemetry_event(

lib/ex_llm/infrastructure/circuit_breaker/telemetry.ex

@@ -70,19 +70,25 @@ defmodule ExLLM.Infrastructure.CircuitBreaker.Telemetry do
   def attach_default_handlers do
     init_metrics()
 
-    :telemetry.attach_many(
-      "ex_llm_circuit_breaker_logger",
-      @events,
-      &handle_telemetry_event/4,
-      %{handler_type: :logger}
-    )
-
-    :telemetry.attach_many(
-      "ex_llm_circuit_breaker_metrics",
-      @events,
-      &handle_telemetry_event/4,
-      %{handler_type: :metrics}
-    )
+    try do
+      :telemetry.attach_many(
+        "ex_llm_circuit_breaker_logger",
+        @events,
+        &handle_telemetry_event/4,
+        %{handler_type: :logger}
+      )
+
+      :telemetry.attach_many(
+        "ex_llm_circuit_breaker_metrics",
+        @events,
+        &handle_telemetry_event/4,
+        %{handler_type: :metrics}
+      )
+    rescue
+      ArgumentError ->
+        # Telemetry application not started yet, ignore
+        :ok
+    end
 
     :ok
   end

mix.exs

@@ -106,6 +106,9 @@ defmodule ExLLM.MixProject do
 
       # HTTP client with middleware support
       {:tesla, "~> 1.8"},
+      
+      # Telemetry instrumentation
+      {:telemetry, "~> 1.0"},
 
       # WebSocket client for Live API
       {:gun, "~> 2.1"},

test/cache/test_openai_capture/v1/chat/completions/test_capture/2025-07-07T01:43:20.143706Z/2025-07-07T01-43-20.143774Z.json

@@ -0,0 +1 @@
+{"request_metadata":{"headers":[],"captured_at":"2025-07-07T01:43:20.143706Z","endpoint":"/v1/chat/completions/test_capture","environment":"test","headers":[],"provider":"test_openai_capture","request_summary":{"model":"gpt-4","temperature":0.7,"max_tokens":100,"messages_count":1},"response_time_ms":523,"status_code":200},"cached_at":"2025-07-07T01:43:20.143821Z","test_context":null,"api_version":null,"response_data":{"choices":[{"finish_reason":"stop","index":0,"message":{"content":"Hello! How can I help you today?","role":"assistant"}}],"created":1234567890,"id":"chatcmpl-123","model":"gpt-4","object":"chat.completion","usage":{"completion_tokens":8,"prompt_tokens":10,"total_tokens":18}},"cache_version":"1.0"}

test/cache/test_openai_capture/v1/chat/completions/test_capture/2025-07-07T01:43:20.143706Z/index.json

@@ -0,0 +1 @@
+{"access_count":0,"cache_hits":0,"cache_key":"test_openai_capture/v1/chat/completions/test_capture/2025-07-07T01:43:20.143706Z","cleanup_before":null,"entries":[{"api_version":null,"content_hash":"6228e3cfc66d523fcf1b6bb51816377535823b90e6630210f8ca8f983d42b35b","cost":null,"filename":"2025-07-07T01-43-20.143774Z.json","response_time_ms":0,"size":721,"status":"success","timestamp":"2025-07-07T01:43:20.143774Z"}],"fallback_strategy":"latest_success","last_accessed":"2025-07-07T01:43:20.144592Z","last_cleanup":null,"test_context":null,"total_requests":1,"ttl":604800000}

test/cache/test_openai_display/v1/chat/completions/test_display/2025-07-07T01:43:20.392401Z/2025-07-07T01-43-20.392524Z.json

@@ -0,0 +1 @@
+{"request_metadata":{"headers":[],"captured_at":"2025-07-07T01:43:20.392401Z","endpoint":"/v1/chat/completions/test_display","environment":"test","headers":[],"provider":"test_openai_display","request_summary":{"model":"gpt-4","temperature":null,"max_tokens":null,"messages_count":0},"response_time_ms":123},"cached_at":"2025-07-07T01:43:20.392636Z","test_context":null,"api_version":null,"response_data":{"choices":[{"finish_reason":"stop","message":{"content":"Test response"}}],"usage":{"completion_tokens":5,"prompt_tokens":10,"total_tokens":15}},"cache_version":"1.0"}

test/cache/test_openai_display/v1/chat/completions/test_display/2025-07-07T01:43:20.392401Z/index.json

@@ -0,0 +1 @@
+{"access_count":0,"cache_hits":0,"cache_key":"test_openai_display/v1/chat/completions/test_display/2025-07-07T01:43:20.392401Z","cleanup_before":null,"entries":[{"api_version":null,"content_hash":"bf70cd379c91f776eed85417d3bac011c6935f3d8d6ea5e2010812a31f24564a","cost":null,"filename":"2025-07-07T01-43-20.392524Z.json","response_time_ms":0,"size":573,"status":"success","timestamp":"2025-07-07T01:43:20.392524Z"}],"fallback_strategy":"latest_success","last_accessed":"2025-07-07T01:43:20.393399Z","last_cleanup":null,"test_context":null,"total_requests":1,"ttl":604800000}