diff --git a/crates/op-host-desktop/src/app_handler.rs b/crates/op-host-desktop/src/app_handler.rs
index 0087ff16e..be23c2435 100644
--- a/crates/op-host-desktop/src/app_handler.rs
+++ b/crates/op-host-desktop/src/app_handler.rs
@@ -272,6 +272,13 @@ impl ApplicationHandler for DesktopApp {
             WindowEvent::CursorMoved { .. } => None,
             _ => Some(settings_io::fingerprint(self.host.editor_state())),
         };
+        let mcp_cli_before = match &event {
+            WindowEvent::CursorMoved { .. } => None,
+            _ => {
+                let settings = &self.host.editor_state().editor_ui.agent_settings;
+                Some((settings.mcp_cli_enabled, settings.mcp_server.port))
+            }
+        };
         match event {
             WindowEvent::CloseRequested => {
                 // The unsaved-changes prompt can abort the close.
@@ -482,6 +489,12 @@ impl ApplicationHandler for DesktopApp {
                 if self.poll_git_clone_job() {
                     self.redraw_dirty = true;
                 }
+                // Drain live MCP requests. Write tools must apply on the
+                // UI-owned EditorState so canvas state, history and
+                // selection stay canonical.
+                if self.poll_mcp_server() {
+                    self.redraw_dirty = true;
+                }
                 // Keep an open Git panel fresh against external repo
                 // changes — re-request a snapshot at most every 2 s.
                 // The query runs on a worker thread, so this never
@@ -529,7 +542,7 @@ impl ApplicationHandler for DesktopApp {
                     event_loop.set_control_flow(ControlFlow::WaitUntil(
                         Instant::now() + Duration::from_millis(33),
                     ));
-                } else if self.current_figma_import.is_some() {
+                } else if self.current_figma_import.is_some() || self.mcp_server_active() {
                     event_loop.set_control_flow(ControlFlow::WaitUntil(
                         Instant::now() + Duration::from_millis(100),
                     ));
@@ -887,6 +900,12 @@ impl ApplicationHandler for DesktopApp {
             }
             _ => {}
         }
+        if self.reconcile_mcp_server_from_settings() {
+            self.request_redraw(true);
+        }
+        if self.reconcile_mcp_cli_integrations(mcp_cli_before) {
+            self.request_redraw(true);
+        }
         if let Some(before) = settings_before {
             settings_io::save_if_changed(self.host.editor_state(), before);
         }
@@ -912,6 +931,9 @@ impl ApplicationHandler for DesktopApp {
         // a focused-but-uncommitted edit isn't silently dropped.
         self.host.flush_settings_input();
         settings_io::save(self.host.editor_state());
+        if let Some(mut server) = self.mcp_server.take() {
+            server.stop();
+        }
         // Save window geometry for next launch. Guarded on a window
         // having existed — a failed startup reaches `exiting` with
         // unseeded geometry and would clobber the previous good save.
diff --git a/crates/op-host-desktop/src/main.rs b/crates/op-host-desktop/src/main.rs
index 520f0e88a..6c7219425 100644
--- a/crates/op-host-desktop/src/main.rs
+++ b/crates/op-host-desktop/src/main.rs
@@ -29,6 +29,9 @@ mod iconify_host;
 mod image_search_session;
 mod keyboard_input;
 mod macos_app;
+mod mcp_integrations;
+mod mcp_live;
+mod mcp_runtime;
 mod mcp_serve;
 mod menu;
 mod model_discovery;
@@ -167,6 +170,8 @@ struct DesktopApp {
     /// periodic refresh that keeps an open panel current against
     /// external repository changes.
     last_git_refresh: Instant,
+    /// Live in-process MCP HTTP server, started from Settings -> MCP.
+    mcp_server: Option<mcp_live::McpLiveServer>,
 }
 
 impl DesktopApp {
@@ -232,6 +237,7 @@ impl DesktopApp {
             git_clone_job: None,
             git_clone_origin: None,
             last_git_refresh: Instant::now(),
+            mcp_server: None,
         }
     }
 
diff --git a/crates/op-host-desktop/src/main_tests.rs b/crates/op-host-desktop/src/main_tests.rs
index 84e6bd397..51fae21be 100644
--- a/crates/op-host-desktop/src/main_tests.rs
+++ b/crates/op-host-desktop/src/main_tests.rs
@@ -66,3 +66,63 @@ fn fresh_app_refits_blank_frame_to_actual_window_size_once() {
     let unchanged = app.host.editor_state().viewport;
     assert_eq!(v, unchanged);
 }
+
+#[test]
+fn live_mcp_http_server_applies_write_requests_to_editor_state() {
+    use std::io::{Read, Write};
+    use std::net::{TcpListener, TcpStream};
+    use std::sync::mpsc;
+    use std::time::{Duration, Instant};
+
+    use op_editor_core::PenNodeExt;
+
+    fn unused_port() -> u16 {
+        let listener = TcpListener::bind(("127.0.0.1", 0)).expect("bind ephemeral port");
+        listener.local_addr().expect("local addr").port()
+    }
+
+    fn post_json(port: u16, body: &str) -> String {
+        let mut stream = TcpStream::connect(("127.0.0.1", port)).expect("connect MCP server");
+        let req = format!(
+            "POST /mcp HTTP/1.1\r\nHost: 127.0.0.1\r\nContent-Length: {}\r\n\r\n{}",
+            body.len(),
+            body
+        );
+        stream.write_all(req.as_bytes()).expect("write request");
+        let mut out = String::new();
+        stream.read_to_string(&mut out).expect("read response");
+        out
+    }
+
+    let port = unused_port();
+    let mut server = mcp_live::McpLiveServer::start(port).expect("start MCP server");
+    let mut state = op_editor_core::EditorState::new();
+    let body = r##"{"jsonrpc":"2.0","id":1,"method":"insert_node","params":{"kind":"rect","name":"From MCP","x":"10","y":"20","width":"100","height":"50","fill_hex":"#00ff00"}}"##;
+    let (tx, rx) = mpsc::channel();
+    std::thread::spawn(move || {
+        let _ = tx.send(post_json(port, body));
+    });
+
+    let started = Instant::now();
+    let response = loop {
+        server.pump(&mut state);
+        if let Ok(response) = rx.try_recv() {
+            break response;
+        }
+        assert!(
+            started.elapsed() < Duration::from_secs(2),
+            "MCP request timed out"
+        );
+        std::thread::sleep(Duration::from_millis(10));
+    };
+
+    assert!(response.starts_with("HTTP/1.1 200 OK"), "{response}");
+    assert!(response.contains(r#""wrote":"true""#), "{response}");
+    assert!(
+        state
+            .active_children()
+            .iter()
+            .any(|node| node.base().name.as_deref() == Some("From MCP")),
+        "MCP write should mutate the live editor state"
+    );
+}
diff --git a/crates/op-host-desktop/src/mcp_integrations.rs b/crates/op-host-desktop/src/mcp_integrations.rs
new file mode 100644
index 000000000..b01881649
--- /dev/null
+++ b/crates/op-host-desktop/src/mcp_integrations.rs
@@ -0,0 +1,258 @@
+//! Terminal-side MCP client configuration for the desktop settings panel.
+//!
+//! The live server is owned by the GUI process. CLI integrations point
+//! at that process over streamable HTTP so terminal agents can reach the
+//! same canvas state the user is editing.
+
+use std::fs;
+use std::path::{Path, PathBuf};
+
+use op_editor_core::agent_settings::McpCli;
+use serde_json::{Map, Value};
+
+const SERVER_NAME: &str = "openpencil";
+
+pub(crate) fn set_cli_enabled(cli: McpCli, enabled: bool, port: u16) -> Result<PathBuf, String> {
+    let home = dirs::home_dir().ok_or_else(|| "home directory not available".to_string())?;
+    let path = config_path(cli, &home, true);
+    set_cli_enabled_at_path(cli, enabled, port, path)
+}
+
+#[cfg(test)]
+fn set_cli_enabled_at_home(
+    cli: McpCli,
+    enabled: bool,
+    port: u16,
+    home: &Path,
+) -> Result<PathBuf, String> {
+    let path = config_path(cli, home, false);
+    set_cli_enabled_at_path(cli, enabled, port, path)
+}
+
+fn set_cli_enabled_at_path(
+    cli: McpCli,
+    enabled: bool,
+    port: u16,
+    path: PathBuf,
+) -> Result<PathBuf, String> {
+    match cli {
+        McpCli::Codex => update_codex_config(&path, enabled, port)?,
+        McpCli::ClaudeCode
+        | McpCli::Gemini
+        | McpCli::OpenCode
+        | McpCli::Kiro
+        | McpCli::GithubCopilot => update_json_config(&path, enabled, port)?,
+    }
+    Ok(path)
+}
+
+fn config_path(cli: McpCli, home: &Path, use_env: bool) -> PathBuf {
+    match cli {
+        McpCli::ClaudeCode => home.join(".claude.json"),
+        McpCli::Codex => {
+            if use_env {
+                std::env::var_os("CODEX_HOME")
+                    .map(PathBuf::from)
+                    .unwrap_or_else(|| home.join(".codex"))
+                    .join("config.toml")
+            } else {
+                home.join(".codex").join("config.toml")
+            }
+        }
+        McpCli::Gemini => home.join(".gemini").join("settings.json"),
+        McpCli::OpenCode => home.join(".opencode").join("config.json"),
+        McpCli::Kiro => home.join(".kiro").join("settings.json"),
+        McpCli::GithubCopilot => home.join(".config").join("github-copilot").join("mcp.json"),
+    }
+}
+
+fn update_json_config(path: &Path, enabled: bool, port: u16) -> Result<(), String> {
+    let mut root = read_json_object(path)?;
+    if enabled {
+        let servers = root
+            .entry("mcpServers")
+            .or_insert_with(|| Value::Object(Map::new()));
+        if !servers.is_object() {
+            *servers = Value::Object(Map::new());
+        }
+        let Some(servers) = servers.as_object_mut() else {
+            return Err("mcpServers is not an object".into());
+        };
+        servers.insert(
+            SERVER_NAME.into(),
+            serde_json::json!({
+                "type": "http",
+                "url": endpoint(port),
+            }),
+        );
+    } else if let Some(servers) = root.get_mut("mcpServers").and_then(Value::as_object_mut) {
+        servers.remove(SERVER_NAME);
+        if servers.is_empty() {
+            root.remove("mcpServers");
+        }
+    }
+    write_json_object(path, &root)
+}
+
+fn read_json_object(path: &Path) -> Result<Map<String, Value>, String> {
+    let text = match fs::read_to_string(path) {
+        Ok(text) => text,
+        Err(e) if e.kind() == std::io::ErrorKind::NotFound => return Ok(Map::new()),
+        Err(e) => return Err(format!("read {}: {e}", path.display())),
+    };
+    if text.trim().is_empty() {
+        return Ok(Map::new());
+    }
+    let value: Value =
+        serde_json::from_str(&text).map_err(|e| format!("parse {}: {e}", path.display()))?;
+    value
+        .as_object()
+        .cloned()
+        .ok_or_else(|| format!("{} must contain a JSON object", path.display()))
+}
+
+fn write_json_object(path: &Path, root: &Map<String, Value>) -> Result<(), String> {
+    if let Some(parent) = path.parent() {
+        fs::create_dir_all(parent).map_err(|e| format!("create {}: {e}", parent.display()))?;
+    }
+    let text = serde_json::to_string_pretty(root)
+        .map_err(|e| format!("serialize {}: {e}", path.display()))?;
+    fs::write(path, format!("{text}\n")).map_err(|e| format!("write {}: {e}", path.display()))
+}
+
+fn update_codex_config(path: &Path, enabled: bool, port: u16) -> Result<(), String> {
+    let existing = match fs::read_to_string(path) {
+        Ok(text) => text,
+        Err(e) if e.kind() == std::io::ErrorKind::NotFound => String::new(),
+        Err(e) => return Err(format!("read {}: {e}", path.display())),
+    };
+    let mut text = remove_codex_server_block(&existing);
+    if enabled {
+        let prefix = text.trim_end();
+        text = String::from(prefix);
+        if !text.is_empty() {
+            text.push_str("\n\n");
+        }
+        text.push_str("[mcp_servers.openpencil]\n");
+        text.push_str(&format!(
+            "url = \"{}\"\n",
+            toml_basic_string_escape(&endpoint(port))
+        ));
+    }
+    if let Some(parent) = path.parent() {
+        fs::create_dir_all(parent).map_err(|e| format!("create {}: {e}", parent.display()))?;
+    }
+    fs::write(path, text).map_err(|e| format!("write {}: {e}", path.display()))
+}
+
+fn remove_codex_server_block(input: &str) -> String {
+    let mut out = String::new();
+    let mut skipping = false;
+    for line in input.split_inclusive('\n') {
+        let trimmed = line.trim();
+        if is_codex_openpencil_table(trimmed) {
+            skipping = true;
+            continue;
+        }
+        if skipping && trimmed.starts_with('[') {
+            skipping = false;
+        }
+        if !skipping {
+            out.push_str(line);
+        }
+    }
+    out
+}
+
+fn is_codex_openpencil_table(line: &str) -> bool {
+    matches!(
+        line,
+        "[mcp_servers.openpencil]"
+            | "[mcp_servers.\"openpencil\"]"
+            | "[\"mcp_servers\".\"openpencil\"]"
+    )
+}
+
+fn endpoint(port: u16) -> String {
+    format!("http://127.0.0.1:{port}/mcp")
+}
+
+fn toml_basic_string_escape(s: &str) -> String {
+    s.replace('\\', "\\\\").replace('"', "\\\"")
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn temp_home(name: &str) -> PathBuf {
+        let path = std::env::temp_dir().join(format!(
+            "openpencil-mcp-{name}-{}-{}",
+            std::process::id(),
+            std::thread::current().name().unwrap_or("test")
+        ));
+        let _ = fs::remove_dir_all(&path);
+        fs::create_dir_all(&path).expect("create temp home");
+        path
+    }
+
+    #[test]
+    fn mcp_json_config_install_and_uninstall_preserves_other_servers() {
+        let home = temp_home("json");
+        let path = home.join(".claude.json");
+        fs::write(
+            &path,
+            r#"{"theme":"dark","mcpServers":{"other":{"type":"http","url":"http://x"}}}"#,
+        )
+        .expect("seed config");
+
+        set_cli_enabled_at_home(McpCli::ClaudeCode, true, 3101, &home).expect("install");
+        let text = fs::read_to_string(&path).expect("read installed");
+        assert!(text.contains(r#""openpencil""#), "{text}");
+        assert!(
+            text.contains(r#""url": "http://127.0.0.1:3101/mcp""#),
+            "{text}"
+        );
+        assert!(text.contains(r#""other""#), "{text}");
+
+        set_cli_enabled_at_home(McpCli::ClaudeCode, false, 3101, &home).expect("uninstall");
+        let text = fs::read_to_string(&path).expect("read uninstalled");
+        assert!(!text.contains(r#""openpencil""#), "{text}");
+        assert!(text.contains(r#""other""#), "{text}");
+
+        let _ = fs::remove_dir_all(home);
+    }
+
+    #[test]
+    fn mcp_codex_config_replaces_existing_openpencil_block() {
+        let home = temp_home("codex");
+        let path = home.join(".codex").join("config.toml");
+        fs::create_dir_all(path.parent().expect("parent")).expect("create codex dir");
+        fs::write(
+            &path,
+            "model = \"gpt-5\"\n\n[mcp_servers.openpencil]\nurl = \"http://old\"\n\n[profiles.dev]\nmodel = \"gpt-5-codex\"\n",
+        )
+        .expect("seed config");
+
+        set_cli_enabled_at_home(McpCli::Codex, true, 3200, &home).expect("install");
+        let text = fs::read_to_string(&path).expect("read installed");
+        assert_eq!(
+            text.matches("[mcp_servers.openpencil]").count(),
+            1,
+            "{text}"
+        );
+        assert!(
+            text.contains("url = \"http://127.0.0.1:3200/mcp\""),
+            "{text}"
+        );
+        assert!(text.contains("[profiles.dev]"), "{text}");
+
+        set_cli_enabled_at_home(McpCli::Codex, false, 3200, &home).expect("uninstall");
+        let text = fs::read_to_string(&path).expect("read uninstalled");
+        assert!(!text.contains("[mcp_servers.openpencil]"), "{text}");
+        assert!(text.contains("model = \"gpt-5\""), "{text}");
+        assert!(text.contains("[profiles.dev]"), "{text}");
+
+        let _ = fs::remove_dir_all(home);
+    }
+}
diff --git a/crates/op-host-desktop/src/mcp_live.rs b/crates/op-host-desktop/src/mcp_live.rs
new file mode 100644
index 000000000..e0069cf00
--- /dev/null
+++ b/crates/op-host-desktop/src/mcp_live.rs
@@ -0,0 +1,206 @@
+//! In-process MCP HTTP server for the live desktop editor.
+//!
+//! The CLI-only `mcp_serve` path owns a file-backed `EditorState`.
+//! This module keeps the GUI as the source of truth: the server thread
+//! requests a fresh snapshot from the UI thread for each HTTP request,
+//! then sends write commands back for the UI thread to apply.
+
+use std::io::Write;
+use std::net::TcpListener;
+use std::sync::mpsc::{self, Receiver, RecvTimeoutError, Sender, SyncSender, TryRecvError};
+use std::thread;
+use std::time::Duration;
+
+use op_editor_core::{EditorCommand, EditorState};
+
+const UI_ACK_TIMEOUT: Duration = Duration::from_secs(5);
+const ACCEPT_IDLE_SLEEP: Duration = Duration::from_millis(25);
+
+pub(crate) struct McpLiveServer {
+    port: u16,
+    req_rx: Receiver<UiRequest>,
+    stop_tx: Sender<()>,
+}
+
+struct ApplyAck {
+    applied: bool,
+    state: EditorState,
+}
+
+enum UiRequest {
+    Snapshot {
+        ack: SyncSender<EditorState>,
+    },
+    Apply {
+        cmd: EditorCommand,
+        ack: SyncSender<ApplyAck>,
+    },
+}
+
+impl McpLiveServer {
+    pub(crate) fn start(port: u16) -> Result<Self, String> {
+        let listener = TcpListener::bind(("127.0.0.1", port))
+            .map_err(|e| format!("bind 127.0.0.1:{port}: {e}"))?;
+        listener
+            .set_nonblocking(true)
+            .map_err(|e| format!("set nonblocking: {e}"))?;
+        let (req_tx, req_rx) = mpsc::channel();
+        let (stop_tx, stop_rx) = mpsc::channel();
+        thread::Builder::new()
+            .name("op-mcp-live-http".into())
+            .spawn(move || server_loop(listener, req_tx, stop_rx))
+            .map_err(|e| format!("spawn MCP live server: {e}"))?;
+        eprintln!("openpencil-desktop mcp: listening on 127.0.0.1:{port}/mcp");
+        Ok(Self {
+            port,
+            req_rx,
+            stop_tx,
+        })
+    }
+
+    pub(crate) fn port(&self) -> u16 {
+        self.port
+    }
+
+    pub(crate) fn pump(&mut self, state: &mut EditorState) -> bool {
+        let mut any_applied = false;
+        loop {
+            match self.req_rx.try_recv() {
+                Ok(UiRequest::Snapshot { ack }) => {
+                    let _ = ack.send(state.clone());
+                }
+                Ok(UiRequest::Apply { cmd, ack }) => {
+                    let applied = state.apply(cmd);
+                    let _ = ack.send(ApplyAck {
+                        applied,
+                        state: state.clone(),
+                    });
+                    any_applied |= applied;
+                }
+                Err(TryRecvError::Empty) => break,
+                Err(TryRecvError::Disconnected) => break,
+            }
+        }
+        any_applied
+    }
+
+    pub(crate) fn stop(&mut self) {
+        let _ = self.stop_tx.send(());
+    }
+}
+
+impl Drop for McpLiveServer {
+    fn drop(&mut self) {
+        self.stop();
+    }
+}
+
+fn server_loop(listener: TcpListener, req_tx: Sender<UiRequest>, stop_rx: Receiver<()>) {
+    loop {
+        match stop_rx.try_recv() {
+            Ok(()) | Err(TryRecvError::Disconnected) => break,
+            Err(TryRecvError::Empty) => {}
+        }
+        match listener.accept() {
+            Ok((mut stream, _addr)) => {
+                let _ = stream.set_read_timeout(Some(UI_ACK_TIMEOUT));
+                let _ = stream.set_write_timeout(Some(UI_ACK_TIMEOUT));
+                if let Err(e) = serve_connection(&mut stream, &req_tx) {
+                    eprintln!("openpencil-desktop mcp: {e}");
+                    let _ = write_http_response(
+                        &mut stream,
+                        "500 Internal Server Error",
+                        &error_json(&e),
+                    );
+                }
+            }
+            Err(e) if e.kind() == std::io::ErrorKind::WouldBlock => {
+                thread::sleep(ACCEPT_IDLE_SLEEP);
+            }
+            Err(e) => {
+                eprintln!("openpencil-desktop mcp: accept: {e}");
+                thread::sleep(ACCEPT_IDLE_SLEEP);
+            }
+        }
+    }
+}
+
+fn serve_connection<S: std::io::Read + std::io::Write>(
+    stream: &mut S,
+    req_tx: &Sender<UiRequest>,
+) -> Result<(), String> {
+    let body = crate::mcp_serve::read_http_request_body(stream)?;
+    let mut state = request_snapshot(req_tx)?;
+    let response =
+        crate::mcp_serve::process_message_with_applier(&mut state, &body, |local_state, cmd| {
+            match request_apply(req_tx, cmd.clone()) {
+                Ok(ack) => {
+                    *local_state = ack.state;
+                    ack.applied
+                }
+                Err(e) => {
+                    eprintln!("openpencil-desktop mcp: apply failed: {e}");
+                    false
+                }
+            }
+        })?
+        .unwrap_or_default();
+    write_http_response(stream, "200 OK", &response)
+}
+
+fn request_snapshot(req_tx: &Sender<UiRequest>) -> Result<EditorState, String> {
+    let (ack_tx, ack_rx) = mpsc::sync_channel(1);
+    req_tx
+        .send(UiRequest::Snapshot { ack: ack_tx })
+        .map_err(|_| "UI thread is not accepting MCP snapshot requests".to_string())?;
+    recv_with_timeout(ack_rx.recv_timeout(UI_ACK_TIMEOUT), "snapshot")
+}
+
+fn request_apply(req_tx: &Sender<UiRequest>, cmd: EditorCommand) -> Result<ApplyAck, String> {
+    let (ack_tx, ack_rx) = mpsc::sync_channel(1);
+    req_tx
+        .send(UiRequest::Apply { cmd, ack: ack_tx })
+        .map_err(|_| "UI thread is not accepting MCP apply requests".to_string())?;
+    recv_with_timeout(ack_rx.recv_timeout(UI_ACK_TIMEOUT), "apply")
+}
+
+fn recv_with_timeout<T>(result: Result<T, RecvTimeoutError>, label: &str) -> Result<T, String> {
+    match result {
+        Ok(v) => Ok(v),
+        Err(RecvTimeoutError::Timeout) => Err(format!("timed out waiting for UI {label} ack")),
+        Err(RecvTimeoutError::Disconnected) => Err(format!("UI {label} ack channel closed")),
+    }
+}
+
+fn write_http_response<S: Write>(stream: &mut S, status: &str, body: &str) -> Result<(), String> {
+    let http = format!(
+        "HTTP/1.1 {status}\r\nContent-Type: application/json\r\n\
+         Content-Length: {}\r\nConnection: close\r\n\r\n{}",
+        body.len(),
+        body
+    );
+    stream
+        .write_all(http.as_bytes())
+        .map_err(|e| format!("http write: {e}"))?;
+    stream.flush().map_err(|e| format!("http flush: {e}"))
+}
+
+fn error_json(message: &str) -> String {
+    format!(r#"{{"error":"{}"}}"#, json_escape(message))
+}
+
+fn json_escape(s: &str) -> String {
+    let mut out = String::with_capacity(s.len());
+    for c in s.chars() {
+        match c {
+            '"' => out.push_str("\\\""),
+            '\\' => out.push_str("\\\\"),
+            '\n' => out.push_str("\\n"),
+            '\r' => out.push_str("\\r"),
+            '\t' => out.push_str("\\t"),
+            c if c.is_control() => out.push(' '),
+            c => out.push(c),
+        }
+    }
+    out
+}
diff --git a/crates/op-host-desktop/src/mcp_runtime.rs b/crates/op-host-desktop/src/mcp_runtime.rs
new file mode 100644
index 000000000..ea2546425
--- /dev/null
+++ b/crates/op-host-desktop/src/mcp_runtime.rs
@@ -0,0 +1,114 @@
+//! Desktop-app glue for the live MCP server and terminal integrations.
+
+use super::{mcp_integrations, mcp_live, DesktopApp};
+
+impl DesktopApp {
+    pub(crate) fn reconcile_mcp_server_from_settings(&mut self) -> bool {
+        let desired = self
+            .host
+            .editor_state()
+            .editor_ui
+            .agent_settings
+            .mcp_server
+            .running;
+        let port = self
+            .host
+            .editor_state()
+            .editor_ui
+            .agent_settings
+            .mcp_server
+            .port;
+        if !desired {
+            if let Some(mut server) = self.mcp_server.take() {
+                server.stop();
+            }
+            return false;
+        }
+        if self
+            .mcp_server
+            .as_ref()
+            .is_some_and(|server| server.port() == port)
+        {
+            return false;
+        }
+        if let Some(mut server) = self.mcp_server.take() {
+            server.stop();
+        }
+        match mcp_live::McpLiveServer::start(port) {
+            Ok(server) => {
+                self.mcp_server = Some(server);
+                false
+            }
+            Err(err) => {
+                eprintln!("openpencil-desktop mcp: failed to start: {err}");
+                self.host
+                    .editor_state_mut()
+                    .editor_ui
+                    .agent_settings
+                    .mcp_server
+                    .running = false;
+                self.host.mark_editor_state_dirty();
+                true
+            }
+        }
+    }
+
+    pub(crate) fn poll_mcp_server(&mut self) -> bool {
+        let Some(server) = self.mcp_server.as_mut() else {
+            return false;
+        };
+        let changed = server.pump(self.host.editor_state_mut());
+        if changed {
+            self.host.mark_editor_state_dirty();
+        }
+        changed
+    }
+
+    pub(crate) fn mcp_server_active(&self) -> bool {
+        self.mcp_server.is_some()
+    }
+
+    pub(crate) fn reconcile_mcp_cli_integrations(
+        &mut self,
+        before: Option<([bool; 6], u16)>,
+    ) -> bool {
+        let Some((before_flags, before_port)) = before else {
+            return false;
+        };
+        let settings = &self.host.editor_state().editor_ui.agent_settings;
+        let after_flags = settings.mcp_cli_enabled;
+        let port = settings.mcp_server.port;
+        if before_flags == after_flags && before_port == port {
+            return false;
+        }
+
+        let mut reverted = false;
+        for (idx, cli) in op_editor_core::agent_settings::McpCli::ALL
+            .iter()
+            .copied()
+            .enumerate()
+        {
+            let flag_changed = before_flags[idx] != after_flags[idx];
+            let enabled_port_changed = before_port != port && after_flags[idx];
+            if !flag_changed && !enabled_port_changed {
+                continue;
+            }
+            if let Err(err) = mcp_integrations::set_cli_enabled(cli, after_flags[idx], port) {
+                eprintln!(
+                    "openpencil-desktop mcp: failed to update {} integration: {err}",
+                    cli.label()
+                );
+                if flag_changed {
+                    self.host
+                        .editor_state_mut()
+                        .editor_ui
+                        .agent_settings
+                        .mcp_cli_enabled[idx] = before_flags[idx];
+                    self.host.mark_editor_state_dirty();
+                    reverted = true;
+                }
+            }
+        }
+        reverted
+    }
+}
diff --git a/crates/op-host-desktop/src/mcp_serve.rs b/crates/op-host-desktop/src/mcp_serve.rs
index be7c1bbc9..51d4993e1 100644
--- a/crates/op-host-desktop/src/mcp_serve.rs
+++ b/crates/op-host-desktop/src/mcp_serve.rs
@@ -28,7 +28,7 @@
 use std::io::{BufRead, BufReader, BufWriter, Write};
 use std::path::PathBuf;
 
-use op_editor_core::EditorState;
+use op_editor_core::{EditorCommand, EditorState};
 use op_mcp::{
     add_node_effect_snapshot, add_page_snapshot, align_selected_snapshot, batch_design_snapshot,
     clear_selection_snapshot, copy_node_snapshot, copy_selected_snapshot, count_nodes_snapshot,
@@ -86,6 +86,34 @@ fn process_message(
     path: &std::path::Path,
     line: &str,
 ) -> Result<Option<String>, String> {
+    let mut applier_failed: Option<String> = None;
+    let response = process_message_with_applier(state, line, |state, cmd| {
+        // `EditorState::apply` runs the pre-validate-then-mutate
+        // discipline; `false` means the command rejected and the
+        // document was NOT changed.
+        if !state.apply(cmd.clone()) {
+            return false;
+        }
+        if let Err(e) = save_editor_state(state, path) {
+            applier_failed = Some(format!("save failed: {e}"));
+            return false;
+        }
+        true
+    })?;
+    if let Some(msg) = applier_failed {
+        eprintln!("openpencil-desktop mcp: {msg}");
+    }
+    Ok(response)
+}
+
+pub(crate) fn process_message_with_applier<F>(
+    state: &mut EditorState,
+    line: &str,
+    mut apply: F,
+) -> Result<Option<String>, String>
+where
+    F: FnMut(&mut EditorState, &EditorCommand) -> bool,
+{
     let trimmed = line.trim();
     if trimmed.is_empty() {
         return Ok(None);
@@ -112,27 +140,11 @@ fn process_message(
     // registry snapshots `state` at build time, so it no longer
     // borrows it once the applier closure mutates it.
     let registry = rebuild_registry(state);
-    let mut applier_failed: Option<String> = None;
     let mut out: Vec<u8> = Vec::new();
     {
         let mut input = std::io::Cursor::new(line.as_bytes());
-        run_stdio_with_applier(&registry, &mut input, &mut out, |cmd| {
-            // `EditorState::apply` runs the pre-validate-then-mutate
-            // discipline; `false` means the command rejected and the
-            // document was NOT changed.
-            if !state.apply(cmd.clone()) {
-                return false;
-            }
-            if let Err(e) = save_editor_state(state, path) {
-                applier_failed = Some(format!("save failed: {e}"));
-                return false;
-            }
-            true
-        })
-        .map_err(|e| format!("dispatch: {e}"))?;
-    }
-    if let Some(msg) = applier_failed {
-        eprintln!("openpencil-desktop mcp: {msg}");
+        run_stdio_with_applier(&registry, &mut input, &mut out, |cmd| apply(state, cmd))
+            .map_err(|e| format!("dispatch: {e}"))?;
     }
     let resp = String::from_utf8_lossy(&out).trim().to_string();
     Ok((!resp.is_empty()).then_some(resp))
@@ -262,7 +274,7 @@ fn serve_http_connection<S: std::io::Read + std::io::Write>(
 /// the `\r\n\r\n` header terminator, parses `Content-Length`, then
 /// reads exactly that many body bytes. The header block is capped so
 /// a malformed peer can't exhaust memory.
-fn read_http_request_body<S: std::io::Read>(stream: &mut S) -> Result<String, String> {
+pub(crate) fn read_http_request_body<S: std::io::Read>(stream: &mut S) -> Result<String, String> {
     const MAX_HEADER: usize = 64 * 1024;
     const MAX_BODY: usize = 8 * 1024 * 1024;
     let mut head: Vec<u8> = Vec::new();