chore: bump ACP schema to v0.6.3

Adds discriminator properties to ContentBlock, MCPServerConfig,
RequestPermissionOutcome, SessionUpdate, and ToolCallContent for
improved type discrimination in the JSON schema.

Updates ContentBlockText description to clarify Markdown support,
indicating that clients SHOULD render text as Markdown.

Author: ThomasK33

README.md

@@ -14,7 +14,7 @@ Learn more about the protocol itself at <https://agentclientprotocol.com>.
 <!-- `$ printf 'go get github.com/coder/acp-go-sdk@v%s\n' "$(cat schema/version)"` as bash -->
 
 ```bash
-go get github.com/coder/[email protected].2
+go get github.com/coder/[email protected].3
 ```
 
 ## Get Started

schema/schema.json

@@ -648,9 +648,12 @@
     },
     "ContentBlock": {
       "description": "Content blocks represent displayable information in the Agent Client Protocol.\n\nThey provide a structured way to handle various types of user-facing content—whether\nit's text from language models, images for analysis, or embedded resources for context.\n\nContent blocks appear in:\n- User prompts sent via `session/prompt`\n- Language model output streamed through `session/update` notifications\n- Progress updates and results from tool calls\n\nThis structure is compatible with the Model Context Protocol (MCP), enabling\nagents to seamlessly forward content from MCP tool outputs without transformation.\n\nSee protocol docs: [Content](https://agentclientprotocol.com/protocol/content)",
+      "discriminator": {
+        "propertyName": "type"
+      },
       "oneOf": [
         {
-          "description": "Plain text content\n\nAll agents MUST support text content blocks in prompts.",
+          "description": "Text content. May be plain text or formatted with Markdown.\n\nAll agents MUST support text content blocks in prompts.\nClients SHOULD render this text as Markdown.",
           "properties": {
             "_meta": {
               "description": "Extension point for implementations"
@@ -1261,7 +1264,10 @@
           "type": "object"
         }
       ],
-      "description": "Configuration for connecting to an MCP (Model Context Protocol) server.\n\nMCP servers provide tools and context that the agent can use when\nprocessing prompts.\n\nSee protocol docs: [MCP Servers](https://agentclientprotocol.com/protocol/session-setup#mcp-servers)"
+      "description": "Configuration for connecting to an MCP (Model Context Protocol) server.\n\nMCP servers provide tools and context that the agent can use when\nprocessing prompts.\n\nSee protocol docs: [MCP Servers](https://agentclientprotocol.com/protocol/session-setup#mcp-servers)",
+      "discriminator": {
+        "propertyName": "type"
+      }
     },
     "ModelId": {
       "description": "**UNSTABLE**\n\nThis capability is not part of the spec yet, and may be removed or changed at any point.\n\nA unique identifier for a model.",
@@ -1613,6 +1619,9 @@
     },
     "RequestPermissionOutcome": {
       "description": "The outcome of a permission request.",
+      "discriminator": {
+        "propertyName": "outcome"
+      },
       "oneOf": [
         {
           "description": "The prompt turn was cancelled before the user responded.\n\nWhen a client sends a `session/cancel` notification to cancel an ongoing\nprompt turn, it MUST respond to all pending `session/request_permission`\nrequests with this `Cancelled` outcome.\n\nSee protocol docs: [Cancellation](https://agentclientprotocol.com/protocol/prompt-turn#cancellation)",
@@ -1837,6 +1846,9 @@
     },
     "SessionUpdate": {
       "description": "Different types of updates that can be sent during session processing.\n\nThese updates provide real-time feedback about the agent's progress.\n\nSee protocol docs: [Agent Reports Output](https://agentclientprotocol.com/protocol/prompt-turn#3-agent-reports-output)",
+      "discriminator": {
+        "propertyName": "sessionUpdate"
+      },
       "oneOf": [
         {
           "description": "A chunk of the user's message being streamed.",
@@ -2249,6 +2261,9 @@
     },
     "ToolCallContent": {
       "description": "Content produced by a tool call.\n\nTool calls can produce different types of content including\nstandard content blocks (text, images) or file diffs.\n\nSee protocol docs: [Content](https://agentclientprotocol.com/protocol/tool-calls#content)",
+      "discriminator": {
+        "propertyName": "type"
+      },
       "oneOf": [
         {
           "description": "Standard content block (text, images, resources).",

schema/version

@@ -1 +1 @@
-0.6.2
+0.6.3

types_gen.go

@@ -1 +1 @@
-0.6.2
+0.6.3