Initial commit: AI Dungeon clone (FastAPI backend + React frontend)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KFsGHju9szibJJa2YJcdbg

backend/app/debuglog.py

@@ -0,0 +1,56 @@
+"""In-memory ring buffer of recent provider requests/responses for the debug page.
+
+API keys never enter the log: only the request body (which carries no
+credentials) and response text are recorded, both truncated.
+"""
+
+import itertools
+from collections import deque
+from datetime import datetime, timezone
+
+MAX_ENTRIES = 30
+MAX_TEXT = 6000
+
+_entries: deque[dict] = deque(maxlen=MAX_ENTRIES)
+_ids = itertools.count(1)
+
+
+def _clip(text: str) -> str:
+    if len(text) <= MAX_TEXT:
+        return text
+    return text[:MAX_TEXT] + f"\n… [{len(text) - MAX_TEXT} more chars truncated]"
+
+
+def _clip_obj(obj):
+    if isinstance(obj, str):
+        return _clip(obj)
+    if isinstance(obj, dict):
+        return {k: _clip_obj(v) for k, v in obj.items()}
+    if isinstance(obj, list):
+        return [_clip_obj(v) for v in obj]
+    return obj
+
+
+def start_entry(url: str, model: str, body: dict) -> dict:
+    entry = {
+        "id": next(_ids),
+        "time": datetime.now(timezone.utc).isoformat(),
+        "url": url,
+        "model": model,
+        "request": _clip_obj(body),
+        "status": "pending",
+        "response": "",
+        "error": None,
+    }
+    _entries.appendleft(entry)
+    return entry
+
+
+def finish_entry(entry: dict, *, response: str = "", error: str | None = None) -> None:
+    entry["response"] = _clip(response)
+    entry["error"] = error
+    entry["status"] = "error" if error else "ok"
+
+
+def recent() -> list[dict]:
+    return list(_entries)