fix(mcp): restore HTTP /mcp endpoint after 855 regression

855 deleted the HTTP /mcp route and pointed agents at ws://...crdt-sync,
but Claude Code's .mcp.json doesn't speak ws:// and the rendezvous WS
never had MCP method handlers wired up — so every spawned Claude Code
agent (gateway-routed and local) booted with zero huskies tools and
died on --permission-prompt-tool=mcp__huskies__prompt_permission.

Restore mcp_post_handler / mcp_get_handler / handle_initialize, re-add
the /mcp route, and revert all three .mcp.json writers to emit
http://localhost:{port}/mcp with explicit "type": "http". Reuses the
already-extracted gateway::jsonrpc types and the surviving
dispatch_tool_call / list_tools surfaces — net add ~140 lines.

Federation work is unaffected: /crdt-sync continues to do CRDT sync,
which is what it was actually doing. MCP-over-WebSocket for cross-LAN
agents was never wired up by 855 and can be done as a proper follow-up
with a regression test that boots a real claude and verifies tool
registration.

Verified end-to-end: /mcp initialize, tools/list (74 tools incl.
prompt_permission), and tools/call all respond correctly from inside
the rebuilt container.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/src/http/mcp/mod.rs

@@ -1,8 +1,8 @@
-//! MCP tool dispatch and schema module.
+//! MCP HTTP endpoint and tool dispatch module.
 //!
-//! Agents no longer connect via an HTTP `/mcp` endpoint. Tool dispatch
-//! is invoked directly by API-based runtimes (Gemini, OpenAI) and by
-//! the WebSocket-based `/crdt-sync` rendezvous channel.
+//! Local Claude Code agents connect to `POST /mcp` with a JSON-RPC 2.0
+//! envelope. Tool dispatch is also invoked directly by API-based runtimes
+//! (Gemini, OpenAI) via [`dispatch::dispatch_tool_call`].
 
 /// MCP tools for agent start, stop, wait, list, and inspect.
 pub mod agent_tools;
@@ -30,3 +30,131 @@ pub mod wizard_tools;
 // Re-export for test code in submodules that references `super::super::handle_tools_list`.
 #[cfg(test)]
 pub(crate) use tools_list::handle_tools_list;
+
+use crate::http::context::AppContext;
+use crate::http::gateway::jsonrpc::JsonRpcResponse;
+use poem::handler;
+use poem::http::StatusCode;
+use poem::web::Data;
+use poem::{Body, Request, Response};
+use serde::Deserialize;
+use serde_json::{Value, json};
+use std::sync::Arc;
+
+#[derive(Deserialize)]
+struct JsonRpcRequest {
+    jsonrpc: String,
+    id: Option<Value>,
+    method: String,
+    #[serde(default)]
+    params: Value,
+}
+
+/// `GET /mcp` — method not allowed (MCP uses POST).
+#[handler]
+pub async fn mcp_get_handler() -> Response {
+    Response::builder()
+        .status(StatusCode::METHOD_NOT_ALLOWED)
+        .body(Body::empty())
+}
+
+/// `POST /mcp` — JSON-RPC 2.0 entry point for `initialize`, `tools/list`,
+/// `tools/call`, and `notifications/*`.
+#[handler]
+pub async fn mcp_post_handler(
+    req: &Request,
+    body: Body,
+    ctx: Data<&Arc<AppContext>>,
+) -> Response {
+    let content_type = req.header("content-type").unwrap_or("");
+    if !content_type.is_empty() && !content_type.contains("application/json") {
+        return json_response(JsonRpcResponse::error(
+            None,
+            -32700,
+            "Unsupported Content-Type; expected application/json".into(),
+        ));
+    }
+
+    let bytes = match body.into_bytes().await {
+        Ok(b) => b,
+        Err(_) => {
+            return json_response(JsonRpcResponse::error(None, -32700, "Parse error".into()));
+        }
+    };
+
+    let rpc: JsonRpcRequest = match serde_json::from_slice(&bytes) {
+        Ok(r) => r,
+        Err(_) => {
+            return json_response(JsonRpcResponse::error(None, -32700, "Parse error".into()));
+        }
+    };
+
+    if rpc.jsonrpc != "2.0" {
+        return json_response(JsonRpcResponse::error(
+            rpc.id,
+            -32600,
+            "Invalid JSON-RPC version".into(),
+        ));
+    }
+
+    if rpc.id.is_none() || rpc.id.as_ref() == Some(&Value::Null) {
+        if rpc.method.starts_with("notifications/") {
+            return Response::builder()
+                .status(StatusCode::ACCEPTED)
+                .body(Body::empty());
+        }
+        return json_response(JsonRpcResponse::error(None, -32600, "Missing id".into()));
+    }
+
+    let resp = match rpc.method.as_str() {
+        "initialize" => handle_initialize(rpc.id),
+        "tools/list" => {
+            JsonRpcResponse::success(rpc.id, json!({ "tools": tools_list::list_tools() }))
+        }
+        "tools/call" => handle_tools_call(rpc.id, &rpc.params, &ctx).await,
+        _ => JsonRpcResponse::error(rpc.id, -32601, format!("Unknown method: {}", rpc.method)),
+    };
+
+    json_response(resp)
+}
+
+fn json_response(resp: JsonRpcResponse) -> Response {
+    let body = serde_json::to_vec(&resp).unwrap_or_default();
+    Response::builder()
+        .status(StatusCode::OK)
+        .header("Content-Type", "application/json")
+        .body(Body::from(body))
+}
+
+fn handle_initialize(id: Option<Value>) -> JsonRpcResponse {
+    JsonRpcResponse::success(
+        id,
+        json!({
+            "protocolVersion": "2025-03-26",
+            "capabilities": { "tools": {} },
+            "serverInfo": { "name": "huskies", "version": "1.0.0" }
+        }),
+    )
+}
+
+async fn handle_tools_call(id: Option<Value>, params: &Value, ctx: &AppContext) -> JsonRpcResponse {
+    let tool_name = params.get("name").and_then(|v| v.as_str()).unwrap_or("");
+    let args = params.get("arguments").cloned().unwrap_or(json!({}));
+
+    match dispatch::dispatch_tool_call(tool_name, args, ctx).await {
+        Ok(content) => JsonRpcResponse::success(
+            id,
+            json!({ "content": [{ "type": "text", "text": content }] }),
+        ),
+        Err(msg) => {
+            crate::slog_warn!("[mcp] Tool call failed: tool={tool_name} error={msg}");
+            JsonRpcResponse::success(
+                id,
+                json!({
+                    "content": [{ "type": "text", "text": msg }],
+                    "isError": true
+                }),
+            )
+        }
+    }
+}

server/src/http/mod.rs

@@ -108,6 +108,10 @@ pub fn build_routes(
         .at("/ws", get(ws::ws_handler))
         .at("/crdt-sync", get(crate::crdt_sync::crdt_sync_handler))
         .at("/rpc", post(rpc_http_handler))
+        .at(
+            "/mcp",
+            post(mcp::mcp_post_handler).get(mcp::mcp_get_handler),
+        )
         .at(
             "/agents/:story_id/:agent_name/stream",
             get(agents_sse::agent_stream),

server/src/io/fs/project.rs

@@ -40,7 +40,7 @@ pub(crate) async fn ensure_project_root_with_story_kit(
         // Always update .mcp.json with the current port so the bot connects to
         // the right endpoint even when HUSKIES_PORT changes between restarts.
         let mcp_content = format!(
-            "{{\n  \"mcpServers\": {{\n    \"huskies\": {{\n      \"url\": \"ws://localhost:{port}/crdt-sync\"\n    }}\n  }}\n}}\n"
+            "{{\n  \"mcpServers\": {{\n    \"huskies\": {{\n      \"type\": \"http\",\n      \"url\": \"http://localhost:{port}/mcp\"\n    }}\n  }}\n}}\n"
         );
         fs::write(path.join(".mcp.json"), mcp_content)
             .map_err(|e| format!("Failed to write .mcp.json: {}", e))?;

server/src/io/fs/scaffold/mod.rs

@@ -69,11 +69,11 @@ pub(crate) fn scaffold_story_kit(root: &Path, port: u16) -> Result<(), String> {
     )?;
 
     // Write .mcp.json at the project root so agents can find the MCP server
-    // via the rendezvous WebSocket endpoint.
+    // via the HTTP MCP endpoint.
     // Only written when missing — never overwrites an existing file, because
     // the port is environment-specific and must not clobber a running instance.
     let mcp_content = format!(
-        "{{\n  \"mcpServers\": {{\n    \"huskies\": {{\n      \"url\": \"ws://localhost:{port}/crdt-sync\"\n    }}\n  }}\n}}\n"
+        "{{\n  \"mcpServers\": {{\n    \"huskies\": {{\n      \"type\": \"http\",\n      \"url\": \"http://localhost:{port}/mcp\"\n    }}\n  }}\n}}\n"
     );
     write_file_if_missing(&root.join(".mcp.json"), &mcp_content)?;
 

server/src/worktree/mod.rs

@@ -37,10 +37,10 @@ pub fn worktree_path(project_root: &Path, story_id: &str) -> PathBuf {
 }
 
 /// Write a `.mcp.json` file in the given directory pointing to the huskies
-/// rendezvous WebSocket endpoint at the given port.
+/// HTTP MCP endpoint at the given port.
 pub fn write_mcp_json(dir: &Path, port: u16) -> Result<(), String> {
     let content = format!(
-        "{{\n  \"mcpServers\": {{\n    \"huskies\": {{\n      \"url\": \"ws://localhost:{port}/crdt-sync\"\n    }}\n  }}\n}}\n"
+        "{{\n  \"mcpServers\": {{\n    \"huskies\": {{\n      \"type\": \"http\",\n      \"url\": \"http://localhost:{port}/mcp\"\n    }}\n  }}\n}}\n"
     );
     std::fs::write(dir.join(".mcp.json"), content).map_err(|e| format!("Write .mcp.json: {e}"))
 }
@@ -91,7 +91,7 @@ mod tests {
         let tmp = TempDir::new().unwrap();
         write_mcp_json(tmp.path(), 4242).unwrap();
         let content = std::fs::read_to_string(tmp.path().join(".mcp.json")).unwrap();
-        assert!(content.contains("ws://localhost:4242/crdt-sync"));
+        assert!(content.contains("http://localhost:4242/mcp"));
     }
 
     #[test]
@@ -99,7 +99,7 @@ mod tests {
         let tmp = TempDir::new().unwrap();
         write_mcp_json(tmp.path(), 3001).unwrap();
         let content = std::fs::read_to_string(tmp.path().join(".mcp.json")).unwrap();
-        assert!(content.contains("ws://localhost:3001/crdt-sync"));
+        assert!(content.contains("http://localhost:3001/mcp"));
     }
 
     #[test]