refactor: improve C# SDK examples structure

.gitignore

@@ -67,3 +67,10 @@ evals/results/
 # Agent-specific local skills (installed via `npx skills add`)
 .claude/skills/
 .cursor/
+
+# C# / .NET
+bin/
+obj/
+*.user
+*.suo
+sdk/csharp/examples/Examples.csproj

sdk/csharp/examples/MainExample.cs

@@ -0,0 +1,92 @@
+/**
+ * Echo bot example demonstrating the Pachca C# SDK.
+ *
+ * Runs 8 steps that exercise the core API patterns:
+ * create, read, nested resource, idempotent POST, thread reply, pin, update, unpin.
+ *
+ * Usage:
+ *
+ *   PACHCA_TOKEN=your_token PACHCA_CHAT_ID=12345 dotnet run -- main
+ */
+
+namespace Pachca.Sdk.Examples;
+
+public static class MainExample
+{
+    public static async Task<int> RunAsync()
+    {
+        var token = Environment.GetEnvironmentVariable("PACHCA_TOKEN")
+            ?? throw new InvalidOperationException("Set PACHCA_TOKEN environment variable");
+        var chatId = int.Parse(
+            Environment.GetEnvironmentVariable("PACHCA_CHAT_ID")
+            ?? throw new InvalidOperationException("Set PACHCA_CHAT_ID environment variable"));
+
+        using var client = new PachcaClient(token);
+
+        // -- Step 1: POST -- Create a message
+        Console.WriteLine("1. Creating message...");
+        var created = await client.Messages.CreateMessageAsync(new MessageCreateRequest
+        {
+            Message = new MessageCreateRequestMessage
+            {
+                EntityId = chatId,
+                Content = "SDK test C# \ud83d\ude80",
+            }
+        });
+        var msgId = created.Id;
+        Console.WriteLine($"   Created message ID: {msgId}");
+
+        // -- Step 2: GET -- Read the message back
+        Console.WriteLine("2. Reading message...");
+        var msg = await client.Messages.GetMessageAsync(msgId);
+        Console.WriteLine($"   Got message: \"{msg.Content}\"");
+
+        // -- Step 3: POST -- Add a reaction (nested resource)
+        Console.WriteLine("3. Adding reaction...");
+        await client.Reactions.AddReactionAsync(msgId, new ReactionRequest { Code = "\ud83d\udc40" });
+        Console.WriteLine("   Added reaction \ud83d\udc40");
+
+        // -- Step 4: POST -- Create a thread (idempotent)
+        Console.WriteLine("4. Creating thread...");
+        var thread = await client.Threads.CreateThreadAsync(msgId);
+        Console.WriteLine($"   Thread ID: {thread.Id}");
+
+        // -- Step 5: POST -- Reply inside the thread
+        Console.WriteLine("5. Replying in thread...");
+        var reply = await client.Messages.CreateMessageAsync(new MessageCreateRequest
+        {
+            Message = new MessageCreateRequestMessage
+            {
+                EntityType = MessageEntityType.Thread,
+                EntityId = (int)thread.Id,
+                Content = $"Echo: {msg.Content}",
+            }
+        });
+        var replyId = reply.Id;
+        Console.WriteLine($"   Reply ID: {replyId}");
+
+        // -- Step 6: POST -- Pin the original message
+        Console.WriteLine("6. Pinning message...");
+        await client.Messages.PinMessageAsync(msgId);
+        Console.WriteLine("   Pinned");
+
+        // -- Step 7: PUT -- Edit the reply
+        Console.WriteLine("7. Updating reply...");
+        await client.Messages.UpdateMessageAsync(replyId, new MessageUpdateRequest
+        {
+            Message = new MessageUpdateRequestMessage
+            {
+                Content = $"{reply.Content} (processed at {DateTimeOffset.UtcNow})",
+            }
+        });
+        Console.WriteLine("   Updated");
+
+        // -- Step 8: DELETE -- Unpin the original message
+        Console.WriteLine("8. Unpinning message...");
+        await client.Messages.UnpinMessageAsync(msgId);
+        Console.WriteLine("   Unpinned");
+
+        Console.WriteLine("\nDone! All 8 steps completed.");
+        return 0;
+    }
+}

sdk/csharp/examples/Program.cs

@@ -0,0 +1,25 @@
+using Pachca.Sdk.Examples;
+
+var example = args.Length > 0 ? args[0].ToLowerInvariant() : "main";
+
+return example switch
+{
+    "main" => await MainExample.RunAsync(),
+    "upload" => await UploadExample.RunAsync(),
+    _ => PrintUsage()
+};
+
+static int PrintUsage()
+{
+    Console.WriteLine("Usage: dotnet run -- <example>");
+    Console.WriteLine();
+    Console.WriteLine("Examples:");
+    Console.WriteLine("  main    - Echo bot (create, read, react, thread, pin, update, unpin)");
+    Console.WriteLine("  upload  - File upload (requires PACHCA_FILE_PATH)");
+    Console.WriteLine();
+    Console.WriteLine("Environment variables:");
+    Console.WriteLine("  PACHCA_TOKEN    - API token (required)");
+    Console.WriteLine("  PACHCA_CHAT_ID  - Chat ID (required)");
+    Console.WriteLine("  PACHCA_FILE_PATH - File path (upload only)");
+    return 1;
+}

sdk/csharp/examples/UploadExample.cs

@@ -0,0 +1,84 @@
+/**
+ * File upload example demonstrating the Pachca C# SDK.
+ *
+ * Uploads a local file and sends it as a message attachment.
+ *
+ * Usage:
+ *
+ *   PACHCA_TOKEN=your_token PACHCA_CHAT_ID=12345 PACHCA_FILE_PATH=./photo.png dotnet run -- upload
+ */
+
+namespace Pachca.Sdk.Examples;
+
+public static class UploadExample
+{
+    public static async Task<int> RunAsync()
+    {
+        var token = Environment.GetEnvironmentVariable("PACHCA_TOKEN")
+            ?? throw new InvalidOperationException("Set PACHCA_TOKEN environment variable");
+        var chatId = int.Parse(
+            Environment.GetEnvironmentVariable("PACHCA_CHAT_ID")
+            ?? throw new InvalidOperationException("Set PACHCA_CHAT_ID environment variable"));
+        var filePath = Environment.GetEnvironmentVariable("PACHCA_FILE_PATH")
+            ?? throw new InvalidOperationException("Set PACHCA_FILE_PATH environment variable");
+
+        var fileName = System.IO.Path.GetFileName(filePath);
+
+        using var client = new PachcaClient(token);
+
+        // -- Step 1: Read the local file
+        Console.WriteLine($"1. Reading file: {filePath}");
+        var fileBytes = await System.IO.File.ReadAllBytesAsync(filePath);
+        var fileSize = fileBytes.Length;
+        Console.WriteLine($"   Size: {fileSize} bytes");
+
+        // -- Step 2: Get upload params
+        Console.WriteLine("2. Getting upload params...");
+        var uploadParams = await client.Common.GetUploadParamsAsync();
+        var key = uploadParams.Key.Replace("${filename}", fileName);
+        Console.WriteLine($"   Got direct_url: {uploadParams.DirectUrl}");
+
+        // -- Step 3: Upload the file via SDK
+        Console.WriteLine("3. Uploading file...");
+        await client.Common.UploadFileAsync(
+            uploadParams.DirectUrl,
+            new FileUploadRequest
+            {
+                ContentDisposition = uploadParams.ContentDisposition,
+                Acl = uploadParams.Acl,
+                Policy = uploadParams.Policy,
+                XAmzCredential = uploadParams.XAmzCredential,
+                XAmzAlgorithm = uploadParams.XAmzAlgorithm,
+                XAmzDate = uploadParams.XAmzDate,
+                XAmzSignature = uploadParams.XAmzSignature,
+                Key = key,
+                File = fileBytes,
+            });
+        Console.WriteLine($"   Uploaded, key: {key}");
+
+        // -- Step 4: Send message with the file attached
+        Console.WriteLine("4. Sending message with attachment...");
+        var msg = await client.Messages.CreateMessageAsync(new MessageCreateRequest
+        {
+            Message = new MessageCreateRequestMessage
+            {
+                EntityId = chatId,
+                Content = $"File upload test: {fileName} \ud83d\ude80",
+                Files = new List<MessageCreateRequestFile>
+                {
+                    new()
+                    {
+                        Key = key,
+                        Name = fileName,
+                        FileType = FileType.File,
+                        Size = fileSize,
+                    }
+                },
+            }
+        });
+        Console.WriteLine($"   Message ID: {msg.Id}");
+
+        Console.WriteLine("\nDone! File uploaded and sent.");
+        return 0;
+    }
+}