Add endpoint usage logging for analysis

- Log all proxied endpoints to /app/cache/endpoint-usage/endpoints.csv
- CSV format: timestamp, method, path, query string
- Add GET /debug/endpoint-usage?api_key=KEY to view statistics
  - Shows top N endpoints by usage count
  - Filter by date with since parameter
  - Returns total requests, unique endpoints, first/last seen
- Add DELETE /debug/endpoint-usage?api_key=KEY to clear logs
- Thread-safe file appending
- Helps identify which endpoints clients actually use
- Can inform future blocklist/allowlist decisions

allstarr/Controllers/JellyfinController.cs

@@ -1671,6 +1671,9 @@ public class JellyfinController : ControllerBase
         // DEBUG: Log EVERY request to see what's happening
         _logger.LogWarning("ProxyRequest called with path: {Path}", path);
         
+        // Log endpoint usage to file for analysis
+        await LogEndpointUsageAsync(path, Request.Method);
+        
         // Block dangerous admin endpoints
         var blockedPrefixes = new[]
         {
@@ -1962,6 +1965,37 @@ public class JellyfinController : ControllerBase
         }
     }
 
+    /// <summary>
+    /// Logs endpoint usage to a file for analysis.
+    /// Creates a CSV file with timestamp, method, path, and query string.
+    /// </summary>
+    private async Task LogEndpointUsageAsync(string path, string method)
+    {
+        try
+        {
+            var logDir = "/app/cache/endpoint-usage";
+            Directory.CreateDirectory(logDir);
+            
+            var logFile = Path.Combine(logDir, "endpoints.csv");
+            var timestamp = DateTime.UtcNow.ToString("yyyy-MM-dd HH:mm:ss");
+            var queryString = Request.QueryString.HasValue ? Request.QueryString.Value : "";
+            
+            // Sanitize path and query for CSV (remove commas, quotes, newlines)
+            var sanitizedPath = path.Replace(",", ";").Replace("\"", "'").Replace("\n", " ").Replace("\r", " ");
+            var sanitizedQuery = queryString.Replace(",", ";").Replace("\"", "'").Replace("\n", " ").Replace("\r", " ");
+            
+            var logLine = $"{timestamp},{method},{sanitizedPath},{sanitizedQuery}\n";
+            
+            // Append to file (thread-safe)
+            await System.IO.File.AppendAllTextAsync(logFile, logLine);
+        }
+        catch (Exception ex)
+        {
+            // Don't let logging failures break the request
+            _logger.LogDebug(ex, "Failed to log endpoint usage");
+        }
+    }
+
     private static string[]? ParseItemTypes(string? includeItemTypes)
     {
         if (string.IsNullOrWhiteSpace(includeItemTypes))
@@ -2484,5 +2518,114 @@ public class JellyfinController : ControllerBase
     }
     
     #endregion
+    
+    #region Debug & Monitoring
+    
+    /// <summary>
+    /// Gets endpoint usage statistics from the log file.
+    /// GET /debug/endpoint-usage?api_key=YOUR_KEY
+    /// Optional query params: top=50 (default 100), since=2024-01-01
+    /// </summary>
+    [HttpGet("debug/endpoint-usage")]
+    [ServiceFilter(typeof(ApiKeyAuthFilter))]
+    public async Task<IActionResult> GetEndpointUsage(
+        [FromQuery] int top = 100,
+        [FromQuery] string? since = null)
+    {
+        try
+        {
+            var logFile = "/app/cache/endpoint-usage/endpoints.csv";
+            
+            if (!System.IO.File.Exists(logFile))
+            {
+                return Ok(new 
+                { 
+                    message = "No endpoint usage data collected yet",
+                    endpoints = Array.Empty<object>()
+                });
+            }
+            
+            var lines = await System.IO.File.ReadAllLinesAsync(logFile);
+            
+            // Parse CSV and filter by date if provided
+            DateTime? sinceDate = null;
+            if (!string.IsNullOrEmpty(since) && DateTime.TryParse(since, out var parsedDate))
+            {
+                sinceDate = parsedDate;
+            }
+            
+            var entries = lines
+                .Select(line => line.Split(','))
+                .Where(parts => parts.Length >= 3)
+                .Where(parts => !sinceDate.HasValue || 
+                    (DateTime.TryParse(parts[0], out var entryDate) && entryDate >= sinceDate.Value))
+                .Select(parts => new
+                {
+                    Timestamp = parts[0],
+                    Method = parts.Length > 1 ? parts[1] : "",
+                    Path = parts.Length > 2 ? parts[2] : "",
+                    Query = parts.Length > 3 ? parts[3] : ""
+                })
+                .ToList();
+            
+            // Group by path and count
+            var pathCounts = entries
+                .GroupBy(e => new { e.Method, e.Path })
+                .Select(g => new
+                {
+                    Method = g.Key.Method,
+                    Path = g.Key.Path,
+                    Count = g.Count(),
+                    FirstSeen = g.Min(e => e.Timestamp),
+                    LastSeen = g.Max(e => e.Timestamp)
+                })
+                .OrderByDescending(x => x.Count)
+                .Take(top)
+                .ToList();
+            
+            return Ok(new
+            {
+                totalRequests = entries.Count,
+                uniqueEndpoints = pathCounts.Count,
+                topEndpoints = pathCounts,
+                logFile = logFile,
+                logSize = new FileInfo(logFile).Length
+            });
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to get endpoint usage");
+            return StatusCode(500, new { error = ex.Message });
+        }
+    }
+
+    /// <summary>
+    /// Clears the endpoint usage log file.
+    /// DELETE /debug/endpoint-usage?api_key=YOUR_KEY
+    /// </summary>
+    [HttpDelete("debug/endpoint-usage")]
+    [ServiceFilter(typeof(ApiKeyAuthFilter))]
+    public IActionResult ClearEndpointUsage()
+    {
+        try
+        {
+            var logFile = "/app/cache/endpoint-usage/endpoints.csv";
+            
+            if (System.IO.File.Exists(logFile))
+            {
+                System.IO.File.Delete(logFile);
+                return Ok(new { status = "success", message = "Endpoint usage log cleared" });
+            }
+            
+            return Ok(new { status = "success", message = "No log file to clear" });
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to clear endpoint usage log");
+            return StatusCode(500, new { error = ex.Message });
+        }
+    }
+    
+    #endregion
 }
 // force rebuild Sun Jan 25 13:22:47 EST 2026