Step 4: Update markdown docs (_meta.symposium.mcp_acp_transport → mcpCapabilities.acp)

Replace all _meta.symposium.mcp_acp_transport references with
mcpCapabilities.acp in:
- md/proxying-acp.md (8 references)
- md/protocol.md (3 references)
- md/conductor.md (2 references)
- md/mcp-bridge.md (1 reference)

Author: nikomatsakis

md/conductor.md

@@ -93,12 +93,12 @@ See [Proxy Mode](#proxy-mode) below for hierarchical chain details.
 
 When components provide MCP servers with ACP transport (`"url": "acp:$UUID"`):
 
-**If agent has `mcp_acp_transport` capability:**
+**If agent has `mcpCapabilities.acp` capability:**
 
 - Pass through MCP server declarations unchanged
 - Agent handles `_mcp/*` messages natively
 
-**If agent lacks `mcp_acp_transport` capability:**
+**If agent lacks `mcpCapabilities.acp` capability:**
 
 - Bind TCP port for each ACP-transport MCP server
 - Transform MCP server spec to use `conductor mcp $port`

md/mcp-bridge.md

@@ -53,7 +53,7 @@ sequenceDiagram
 
     Proxy->>Conductor: session/new {<br/>  mcp_servers: [{<br/>    name: "research-tools",<br/>    url: "acp:uuid-123"<br/>  }]<br/>}
 
-    Note over Conductor: Detects acp: transport<br/>Agent lacks mcp_acp_transport capability
+    Note over Conductor: Detects acp: transport<br/>Agent lacks mcpCapabilities.acp
 
     Conductor->>Conductor: Bind TCP listener on port 54321
 

md/protocol.md

@@ -286,21 +286,23 @@ Send an MCP notification over the ACP connection. Bidirectional like `_mcp/reque
 }
 ```
 
-### Agent Capability: `mcp_acp_transport`
+### Agent Capability: `mcpCapabilities.acp`
 
 Agents that natively support MCP-over-ACP declare this capability:
 
 ```json
 {
-  "_meta": {
-    "mcp_acp_transport": true
+  "agentCapabilities": {
+    "mcpCapabilities": {
+      "acp": true
+    }
   }
 }
 ```
 
 **Conductor behavior:**
 
-- If the agent has `mcp_acp_transport: true`, conductor passes MCP server declarations through unchanged
+- If the agent has `mcpCapabilities.acp: true`, conductor passes MCP server declarations through unchanged
 - If the agent lacks this capability, conductor performs **bridging adaptation**:
   1. Binds a TCP port (e.g., `localhost:54321`)
   2. Transforms MCP server to use `conductor mcp PORT` command with stdio transport

md/proxying-acp.md

@@ -108,7 +108,7 @@ P/ACP's orchestrator is called the **Conductor** (binary name: `conductor`). The
 
 **Key adaptation: MCP Bridge**
 
-- If the agent supports `mcp_acp_transport`, conductor passes MCP servers with ACP transport through unchanged
+- If the agent supports `mcpCapabilities.acp`, conductor passes MCP servers with ACP transport through unchanged
 - If not, conductor spawns `conductor mcp $port` processes to bridge between stdio (MCP) and ACP messages
 - Components can provide MCP servers without requiring agent modifications
 - See "MCP Bridge" section in Implementation Details for full protocol
@@ -356,26 +356,28 @@ Components declare MCP servers with ACP transport by using the HTTP MCP server f
 
 The `acp:$UUID` URL signals ACP transport. The component generates the UUID to identify which component handles calls to this MCP server.
 
-#### Agent Capability: `mcp_acp_transport`
+#### Agent Capability: `mcpCapabilities.acp`
 
 Agents that natively support MCP-over-ACP declare this capability:
 
 ```json
 {
-  "_meta": {
-    "mcp_acp_transport": true
+  "agentCapabilities": {
+    "mcpCapabilities": {
+      "acp": true
+    }
   }
 }
 ```
 
 **Conductor behavior:**
 
-- If the final agent has `mcp_acp_transport: true`, conductor passes MCP server declarations through unchanged
+- If the final agent has `mcpCapabilities.acp: true`, conductor passes MCP server declarations through unchanged
 - If the final agent lacks this capability, conductor performs **bridging adaptation**:
   1. Binds a fresh TCP port (e.g., `localhost:54321`)
   2. Transforms the MCP server declaration to use `conductor mcp $port` as the command
   3. Spawns `conductor mcp $port` which connects back via TCP and bridges to ACP messages
-  4. Always advertises `mcp_acp_transport: true` to intermediate components
+  4. Always advertises `mcpCapabilities.acp: true` to intermediate components
 
 #### Bridging Transformation Example
 
@@ -391,7 +393,7 @@ Agents that natively support MCP-over-ACP declare this capability:
 }
 ```
 
-**Transformed spec (passed to agent without `mcp_acp_transport`):**
+**Transformed spec (passed to agent without `mcpCapabilities.acp`):**
 
 ```json
 {
@@ -586,12 +588,12 @@ These extensions are beyond the scope of this initial RFD and will be defined as
 **Phase 2: Conductor Agent Mode - MCP Detection & Bridging**
 
 - [ ] Detect `"transport": "http", "url": "acp:$UUID"` MCP servers in initialization
-- [ ] Check final agent for `mcp_acp_transport` capability
+- [ ] Check final agent for `mcpCapabilities.acp` capability
 - [ ] Bind ephemeral TCP ports when bridging needed
 - [ ] Transform MCP server specs to use `conductor mcp $port`
 - [ ] Spawn `conductor mcp $port` subprocess per ACP-transport MCP server
 - [ ] Store mapping: `UUID → TCP port → bridge process`
-- [ ] Always advertise `mcp_acp_transport: true` to intermediate components
+- [ ] Always advertise `mcpCapabilities.acp: true` to intermediate components
 - [ ] Integration test: full chain with MCP bridging
 
 **Phase 3: `_mcp/*` Message Routing**