diff --git a/src/renderer/Metal.zig b/src/renderer/Metal.zig
index 0b7d79c10..e1fb7b37d 100644
--- a/src/renderer/Metal.zig
+++ b/src/renderer/Metal.zig
@@ -469,6 +469,12 @@ pub fn render(
         state.mutex.lock();
         defer state.mutex.unlock();
 
+        // If we're in a synchronized output state, we pause all rendering.
+        if (state.terminal.modes.get(.synchronized_output)) {
+            log.debug("synchronized output started, skipping render", .{});
+            return;
+        }
+
         self.cursor_visible = visible: {
             // If the cursor is explicitly not visible in the state,
             // then it is not visible.
diff --git a/src/renderer/OpenGL.zig b/src/renderer/OpenGL.zig
index d7b5d6b5c..a05e4c287 100644
--- a/src/renderer/OpenGL.zig
+++ b/src/renderer/OpenGL.zig
@@ -711,6 +711,12 @@ pub fn render(
         state.mutex.lock();
         defer state.mutex.unlock();
 
+        // If we're in a synchronized output state, we pause all rendering.
+        if (state.terminal.modes.get(.synchronized_output)) {
+            log.debug("synchronized output started, skipping render", .{});
+            return;
+        }
+
         self.cursor_visible = visible: {
             // If the cursor is explicitly not visible in the state,
             // then it is not visible.
diff --git a/src/terminal/Parser.zig b/src/terminal/Parser.zig
index 90aaefcd6..ee65a165f 100644
--- a/src/terminal/Parser.zig
+++ b/src/terminal/Parser.zig
@@ -694,6 +694,33 @@ test "csi: colon for non-m final" {
     try testing.expect(p.state == .ground);
 }
 
+test "csi: request mode decrqm" {
+    var p = init();
+    _ = p.next(0x1B);
+    for ("[?2026$") |c| {
+        const a = p.next(c);
+        try testing.expect(a[0] == null);
+        try testing.expect(a[1] == null);
+        try testing.expect(a[2] == null);
+    }
+
+    {
+        const a = p.next('p');
+        try testing.expect(p.state == .ground);
+        try testing.expect(a[0] == null);
+        try testing.expect(a[1].? == .csi_dispatch);
+        try testing.expect(a[2] == null);
+
+        const d = a[1].?.csi_dispatch;
+        try testing.expect(d.final == 'p');
+        try testing.expectEqual(@as(usize, 2), d.intermediates.len);
+        try testing.expectEqual(@as(usize, 1), d.params.len);
+        try testing.expectEqual(@as(u16, '?'), d.intermediates[0]);
+        try testing.expectEqual(@as(u16, '$'), d.intermediates[1]);
+        try testing.expectEqual(@as(u16, 2026), d.params[0]);
+    }
+}
+
 test "osc: change window title" {
     var p = init();
     _ = p.next(0x1B);
diff --git a/src/terminal/modes.zig b/src/terminal/modes.zig
index a03326c79..49b28d86f 100644
--- a/src/terminal/modes.zig
+++ b/src/terminal/modes.zig
@@ -170,6 +170,7 @@ const entries: []const ModeEntry = &.{
     .{ .name = "alt_sends_escape", .value = 1039 },
     .{ .name = "alt_screen_save_cursor_clear_enter", .value = 1049 },
     .{ .name = "bracketed_paste", .value = 2004 },
+    .{ .name = "synchronized_output", .value = 2026 },
 };
 
 test {
diff --git a/src/terminal/stream.zig b/src/terminal/stream.zig
index 4e3774e4d..57dc801b7 100644
--- a/src/terminal/stream.zig
+++ b/src/terminal/stream.zig
@@ -569,6 +569,35 @@ pub fn Stream(comptime Handler: type) type {
                     ),
                 },
 
+                // DECRQM - Request Mode
+                'p' => switch (action.intermediates.len) {
+                    2 => decrqm: {
+                        if (action.intermediates[0] != '?' and
+                            action.intermediates[1] != '$')
+                        {
+                            log.warn(
+                                "ignoring unimplemented CSI p with intermediates: {s}",
+                                .{action.intermediates},
+                            );
+                            break :decrqm;
+                        }
+
+                        if (action.params.len != 1) {
+                            log.warn("invalid DECRQM command: {}", .{action});
+                            break :decrqm;
+                        }
+
+                        if (@hasDecl(T, "requestMode")) {
+                            try self.handler.requestMode(action.params[0]);
+                        } else log.warn("unimplemented DECRQM callback: {}", .{action});
+                    },
+
+                    else => log.warn(
+                        "ignoring unimplemented CSI p with intermediates: {s}",
+                        .{action.intermediates},
+                    ),
+                },
+
                 // DECSCUSR - Select Cursor Style
                 // TODO: test
                 'q' => if (@hasDecl(T, "setCursorStyle")) try self.handler.setCursorStyle(
diff --git a/src/termio/Exec.zig b/src/termio/Exec.zig
index 007507e12..95b5ab962 100644
--- a/src/termio/Exec.zig
+++ b/src/termio/Exec.zig
@@ -293,9 +293,25 @@ pub fn resize(
         // Update our pixel sizes
         self.terminal.width_px = padded_size.width;
         self.terminal.height_px = padded_size.height;
+
+        // Disable synchronized output mode so that we show changes
+        // immediately for a resize. This is allowed by the spec.
+        self.terminal.modes.set(.synchronized_output, false);
+
+        // Wake up our renderer so any changes will be shown asap
+        self.renderer_wakeup.notify() catch {};
     }
 }
 
+/// Reset the synchronized output mode. This is usually called by timer
+/// expiration from the termio thread.
+pub fn resetSynchronizedOutput(self: *Exec) void {
+    self.renderer_state.mutex.lock();
+    defer self.renderer_state.mutex.unlock();
+    self.terminal.modes.set(.synchronized_output, false);
+    self.renderer_wakeup.notify() catch {};
+}
+
 /// Clear the screen.
 pub fn clearScreen(self: *Exec, history: bool) !void {
     {
@@ -1272,6 +1288,27 @@ const StreamHandler = struct {
         }
     }
 
+    pub fn requestMode(self: *StreamHandler, mode_raw: u16) !void {
+        // Get the mode value and respond.
+        const code: u8 = code: {
+            if (!terminal.modes.hasSupport(mode_raw)) break :code 0;
+            if (self.terminal.modes.get(@enumFromInt(mode_raw))) break :code 1;
+            break :code 2;
+        };
+
+        var msg: termio.Message = .{ .write_small = .{} };
+        const resp = try std.fmt.bufPrint(
+            &msg.write_small.data,
+            "\x1B[?{};{}$y",
+            .{
+                mode_raw,
+                code,
+            },
+        );
+        msg.write_small.len = @intCast(resp.len);
+        self.messageWriter(msg);
+    }
+
     pub fn saveMode(self: *StreamHandler, mode: terminal.Mode) !void {
         // log.debug("save mode={}", .{mode});
         self.terminal.modes.save(mode);
@@ -1334,6 +1371,13 @@ const StreamHandler = struct {
                 if (enabled) .@"132_cols" else .@"80_cols",
             ),
 
+            // We need to start a timer to prevent the emulator being hung
+            // forever.
+            .synchronized_output => {
+                if (enabled) self.messageWriter(.{ .start_synchronized_output = {} });
+                try self.queueRender();
+            },
+
             .mouse_event_x10 => self.terminal.flags.mouse_event = if (enabled) .x10 else .none,
             .mouse_event_normal => self.terminal.flags.mouse_event = if (enabled) .normal else .none,
             .mouse_event_button => self.terminal.flags.mouse_event = if (enabled) .button else .none,
diff --git a/src/termio/Thread.zig b/src/termio/Thread.zig
index 2c32d459f..0b345ac1f 100644
--- a/src/termio/Thread.zig
+++ b/src/termio/Thread.zig
@@ -27,6 +27,10 @@ const Coalesce = struct {
     resize: ?termio.Message.Resize = null,
 };
 
+/// The number of milliseconds before we reset the synchronized output flag
+/// if the running program hasn't already.
+const sync_reset_ms = 1000;
+
 /// Allocator used for some state
 alloc: std.mem.Allocator,
 
@@ -49,6 +53,12 @@ coalesce_c: xev.Completion = .{},
 coalesce_cancel_c: xev.Completion = .{},
 coalesce_data: Coalesce = .{},
 
+/// This timer is used to reset synchronized output modes so that
+/// the terminal doesn't freeze with a bad actor.
+sync_reset: xev.Timer,
+sync_reset_c: xev.Completion = .{},
+sync_reset_cancel_c: xev.Completion = .{},
+
 /// The underlying IO implementation.
 impl: *termio.Impl,
 
@@ -79,6 +89,10 @@ pub fn init(
     var coalesce_h = try xev.Timer.init();
     errdefer coalesce_h.deinit();
 
+    // This timer is used to reset synchronized output modes.
+    var sync_reset_h = try xev.Timer.init();
+    errdefer sync_reset_h.deinit();
+
     // The mailbox for messaging this thread
     var mailbox = try Mailbox.create(alloc);
     errdefer mailbox.destroy(alloc);
@@ -89,6 +103,7 @@ pub fn init(
         .wakeup = wakeup_h,
         .stop = stop_h,
         .coalesce = coalesce_h,
+        .sync_reset = sync_reset_h,
         .impl = impl,
         .mailbox = mailbox,
     };
@@ -98,6 +113,7 @@ pub fn init(
 /// completes executing; the caller must join prior to this.
 pub fn deinit(self: *Thread) void {
     self.coalesce.deinit();
+    self.sync_reset.deinit();
     self.stop.deinit();
     self.wakeup.deinit();
     self.loop.deinit();
@@ -158,6 +174,7 @@ fn drainMailbox(self: *Thread) !void {
             .clear_screen => |v| try self.impl.clearScreen(v.history),
             .scroll_viewport => |v| try self.impl.scrollViewport(v),
             .jump_to_prompt => |v| try self.impl.jumpToPrompt(v),
+            .start_synchronized_output => self.startSynchronizedOutput(),
             .write_small => |v| try self.impl.queueWrite(v.data[0..v.len]),
             .write_stable => |v| try self.impl.queueWrite(v),
             .write_alloc => |v| {
@@ -174,6 +191,18 @@ fn drainMailbox(self: *Thread) !void {
     }
 }
 
+fn startSynchronizedOutput(self: *Thread) void {
+    self.sync_reset.reset(
+        &self.loop,
+        &self.sync_reset_c,
+        &self.sync_reset_cancel_c,
+        sync_reset_ms,
+        Thread,
+        self,
+        syncResetCallback,
+    );
+}
+
 fn handleResize(self: *Thread, resize: termio.Message.Resize) void {
     self.coalesce_data.resize = resize;
 
@@ -193,6 +222,25 @@ fn handleResize(self: *Thread, resize: termio.Message.Resize) void {
     );
 }
 
+fn syncResetCallback(
+    self_: ?*Thread,
+    _: *xev.Loop,
+    _: *xev.Completion,
+    r: xev.Timer.RunError!void,
+) xev.CallbackAction {
+    _ = r catch |err| switch (err) {
+        error.Canceled => {},
+        else => {
+            log.warn("error during sync reset callback err={}", .{err});
+            return .disarm;
+        },
+    };
+
+    const self = self_ orelse return .disarm;
+    self.impl.resetSynchronizedOutput();
+    return .disarm;
+}
+
 fn coalesceCallback(
     self_: ?*Thread,
     _: *xev.Loop,
diff --git a/src/termio/message.zig b/src/termio/message.zig
index d0fc9f7c3..06e8aae85 100644
--- a/src/termio/message.zig
+++ b/src/termio/message.zig
@@ -51,6 +51,11 @@ pub const Message = union(enum) {
     /// Jump forward/backward n prompts.
     jump_to_prompt: isize,
 
+    /// Send this when a synchronized output mode is started. This will
+    /// start the timer so that the output mode is disabled after a
+    /// period of time so that a bad actor can't hang the terminal.
+    start_synchronized_output: void,
+
     /// Write where the data fits in the union.
     write_small: WriteReq.Small,