feat: add Logfire tracking/tracing for observability

- logfire.configure() with send_to_logfire="if-token-present" so it's
a safe no-op locally without a token, and instrument_httpx() to
auto-capture every Mistral API call (latency, status, errors).
- Wrap get_dm_response in a span and log exceptions instead of only
returning them as a chat string, since friends using the Space
won't otherwise surface failures anywhere visible.
- Document LOGFIRE_TOKEN in .env.example.

Verified locally end-to-end: traces show up in the Logfire project
both with and without a token present.

.env.example

@@ -6,3 +6,8 @@ MISTRAL_API_KEY=your_api_key_here
 # Get your token at: https://huggingface.co/settings/tokens
 # Required to push to Hugging Face Spaces
 HF_TOKEN=your_hf_token_here
+
+# Pydantic Logfire write token for tracking/tracing
+# Get your token at: https://logfire.pydantic.dev/ (project settings > write tokens)
+# Optional: without it, logfire.configure(send_to_logfire="if-token-present") is a no-op
+LOGFIRE_TOKEN=your_logfire_token_here

app.py

@@ -1,8 +1,12 @@
 import os
 import random
 import gradio as gr
+import logfire
 from mistralai.client import Mistral
 
+logfire.configure(service_name="dnd-dm-assistant", send_to_logfire="if-token-present")
+logfire.instrument_httpx(capture_all=True)
+
 # Load Mistral API key from environment variable
 MISTRAL_API_KEY = os.environ.get("MISTRAL_API_KEY")
 
@@ -34,28 +38,35 @@ def roll_dice(dice_type: str) -> str:
 
 def get_dm_response(message: str, history: list[tuple[str, str]]) -> str:
     """Get a response from the Mistral DM."""
-    if client is None:
-        return "Error: Mistral API key not configured. Set MISTRAL_API_KEY environment variable."
-    
-    try:
-        # Build messages including system prompt and conversation history
-        messages = [{"role": "system", "content": SYSTEM_PROMPT}]
-        for user_msg, assistant_msg in history:
-            messages.append({"role": "user", "content": user_msg})
-            messages.append({"role": "assistant", "content": assistant_msg})
-        messages.append({"role": "user", "content": message})
-
-        # Get response from Mistral
-        response = client.chat.complete(
-            model="mistral-medium-latest",
-            messages=messages,
-            temperature=0.7,
-            max_tokens=150,
-        )
-        
-        return response.choices[0].message.content
-    except Exception as e:
-        return f"Error: Failed to get response from Mistral. {str(e)}"
+    with logfire.span(
+        "get_dm_response",
+        message_length=len(message),
+        history_turns=len(history),
+    ):
+        if client is None:
+            logfire.error("Mistral API key not configured")
+            return "Error: Mistral API key not configured. Set MISTRAL_API_KEY environment variable."
+
+        try:
+            # Build messages including system prompt and conversation history
+            messages = [{"role": "system", "content": SYSTEM_PROMPT}]
+            for user_msg, assistant_msg in history:
+                messages.append({"role": "user", "content": user_msg})
+                messages.append({"role": "assistant", "content": assistant_msg})
+            messages.append({"role": "user", "content": message})
+
+            # Get response from Mistral
+            response = client.chat.complete(
+                model="mistral-medium-latest",
+                messages=messages,
+                temperature=0.7,
+                max_tokens=150,
+            )
+
+            return response.choices[0].message.content
+        except Exception as e:
+            logfire.exception("Mistral request failed")
+            return f"Error: Failed to get response from Mistral. {str(e)}"
 
 
 def respond(message: str, history: list[tuple[str, str]]) -> tuple[str, list[tuple[str, str]]]:

requirements.txt

@@ -1,3 +1,4 @@
 mistralai>=1.0.0
 python-dotenv>=1.0.0
 gradio==6.20.0
+logfire[httpx]