chore: clean up MITM logs and add Google SSE tests

- Demote non-LLM request logs to debug (only streamGenerateContent at info)
- Demote non-streaming response headers to debug
- Add 5 Google SSE parser tests (single event, multi-event accumulation,
  chunked framing, completion detection, no-thinking-tokens)
- Fix unused variable warning in proxy.rs

src/mitm/intercept.rs

@@ -291,5 +291,156 @@ mod tests {
         let usage = acc.into_usage();
         assert_eq!(usage.input_tokens, 200);
         assert_eq!(usage.output_tokens, 75);
+        assert_eq!(usage.api_provider, Some("anthropic".to_string()));
+    }
+
+    #[test]
+    fn test_google_sse_single_event() {
+        let mut acc = StreamingAccumulator::new();
+
+        let event = serde_json::json!({
+            "response": {
+                "candidates": [{"content": {"role": "model", "parts": [{"text": "4"}]}}],
+                "usageMetadata": {
+                    "promptTokenCount": 1514,
+                    "candidatesTokenCount": 25,
+                    "totalTokenCount": 1539,
+                    "thoughtsTokenCount": 52
+                },
+                "modelVersion": "gemini-3-flash",
+                "responseId": "abc123"
+            },
+            "traceId": "trace456",
+            "metadata": {}
+        });
+
+        acc.process_event(&event);
+        assert_eq!(acc.input_tokens, 1514);
+        assert_eq!(acc.output_tokens, 25);
+        assert_eq!(acc.thinking_tokens, 52);
+        assert_eq!(acc.model, Some("gemini-3-flash".to_string()));
+        assert!(!acc.is_complete); // no finishReason yet
+        assert_eq!(acc.api_provider, Some("google".to_string()));
+    }
+
+    #[test]
+    fn test_google_sse_multi_event_accumulation() {
+        let mut acc = StreamingAccumulator::new();
+
+        // First event — partial response
+        let event1 = serde_json::json!({
+            "response": {
+                "candidates": [{"content": {"role": "model", "parts": [{"text": "Hello"}]}}],
+                "usageMetadata": {
+                    "promptTokenCount": 1514,
+                    "candidatesTokenCount": 6,
+                    "totalTokenCount": 1520
+                },
+                "modelVersion": "gemini-2.5-flash-lite"
+            },
+            "traceId": "t1",
+            "metadata": {}
+        });
+        acc.process_event(&event1);
+        assert_eq!(acc.output_tokens, 6);
+        assert!(!acc.is_complete);
+
+        // Second event — more output
+        let event2 = serde_json::json!({
+            "response": {
+                "candidates": [{"content": {"role": "model", "parts": [{"text": " world"}]}}],
+                "usageMetadata": {
+                    "promptTokenCount": 1514,
+                    "candidatesTokenCount": 22,
+                    "totalTokenCount": 1536
+                },
+                "modelVersion": "gemini-2.5-flash-lite"
+            },
+            "traceId": "t1",
+            "metadata": {}
+        });
+        acc.process_event(&event2);
+        assert_eq!(acc.output_tokens, 22); // cumulative, not additive
+
+        // Third event — completion
+        let event3 = serde_json::json!({
+            "response": {
+                "candidates": [{"content": {"role": "model", "parts": [{"text": "!"}]},
+                    "finishReason": "STOP"}],
+                "usageMetadata": {
+                    "promptTokenCount": 1514,
+                    "candidatesTokenCount": 25,
+                    "totalTokenCount": 1539,
+                    "thoughtsTokenCount": 52
+                },
+                "modelVersion": "gemini-2.5-flash-lite"
+            },
+            "traceId": "t1",
+            "metadata": {}
+        });
+        acc.process_event(&event3);
+        assert!(acc.is_complete);
+        assert_eq!(acc.output_tokens, 25);
+        assert_eq!(acc.thinking_tokens, 52);
+        assert_eq!(acc.stop_reason, Some("STOP".to_string()));
+
+        let usage = acc.into_usage();
+        assert_eq!(usage.input_tokens, 1514);
+        assert_eq!(usage.output_tokens, 25);
+        assert_eq!(usage.thinking_output_tokens, 52);
+        assert_eq!(usage.model, Some("gemini-2.5-flash-lite".to_string()));
+        assert_eq!(usage.api_provider, Some("google".to_string()));
+    }
+
+    #[test]
+    fn test_google_sse_parse_streaming_chunk() {
+        // Simulates real SSE data with HTTP chunked framing (hex sizes on their own lines)
+        let chunk = r#"150
+data: {"response": {"candidates": [{"content": {"role": "model","parts": [{"text": "4"}]}}],"usageMetadata": {"promptTokenCount": 14615,"candidatesTokenCount": 1,"totalTokenCount": 14668,"thoughtsTokenCount": 52},"modelVersion": "gemini-3-flash","responseId": "agaRacPLC4WHz7IPreOl8QM"},"traceId": "8145be7112baf823","metadata": {}}
+
+
+2f1
+data: {"response": {"candidates": [{"content": {"role": "model","parts": [{"text": ""}]},"finishReason": "STOP"}],"usageMetadata": {"promptTokenCount": 14615,"candidatesTokenCount": 1,"totalTokenCount": 14668,"thoughtsTokenCount": 52},"modelVersion": "gemini-3-flash","responseId": "agaRacPLC4WHz7IPreOl8QM"},"traceId": "8145be7112baf823","metadata": {}}
+
+
+0
+"#;
+
+        let mut acc = StreamingAccumulator::new();
+        parse_streaming_chunk(chunk, &mut acc);
+
+        assert_eq!(acc.input_tokens, 14615);
+        assert_eq!(acc.output_tokens, 1);
+        assert_eq!(acc.thinking_tokens, 52);
+        assert!(acc.is_complete);
+        assert_eq!(acc.model, Some("gemini-3-flash".to_string()));
+        assert_eq!(acc.stop_reason, Some("STOP".to_string()));
+    }
+
+    #[test]
+    fn test_google_sse_no_thinking_tokens() {
+        let mut acc = StreamingAccumulator::new();
+
+        let event = serde_json::json!({
+            "response": {
+                "candidates": [{"content": {"role": "model", "parts": [{"text": "hi"}]},
+                    "finishReason": "STOP"}],
+                "usageMetadata": {
+                    "promptTokenCount": 100,
+                    "candidatesTokenCount": 5,
+                    "totalTokenCount": 105
+                },
+                "modelVersion": "gemini-2.5-flash-lite"
+            },
+            "traceId": "t1",
+            "metadata": {}
+        });
+
+        acc.process_event(&event);
+        assert_eq!(acc.thinking_tokens, 0); // no thoughtsTokenCount field
+        assert!(acc.is_complete);
+
+        let usage = acc.into_usage();
+        assert_eq!(usage.thinking_output_tokens, 0);
     }
 }