diff --git a/pkg-py/src/querychat/_querychat.py b/pkg-py/src/querychat/_querychat.py
index 5292061d..cda4b7ce 100644
--- a/pkg-py/src/querychat/_querychat.py
+++ b/pkg-py/src/querychat/_querychat.py
@@ -167,6 +167,7 @@ def sidebar(
         *,
         width: int = 400,
         height: str = "100%",
+        fillable: bool = True,
         **kwargs,
     ) -> ui.Sidebar:
         """
@@ -178,6 +179,8 @@ def sidebar(
             Width of the sidebar in pixels.
         height
             Height of the sidebar.
+        fillable
+            Whether the sidebar should be fillable. Default is `True`.
         **kwargs
             Additional arguments passed to `shiny.ui.sidebar()`.
 
@@ -191,6 +194,7 @@ def sidebar(
             self.ui(),
             width=width,
             height=height,
+            fillable=fillable,
             class_="querychat-sidebar",
             **kwargs,
         )
diff --git a/pkg-r/R/QueryChat.R b/pkg-r/R/QueryChat.R
index 3bde18bf..e2c2101a 100644
--- a/pkg-r/R/QueryChat.R
+++ b/pkg-r/R/QueryChat.R
@@ -383,6 +383,7 @@ QueryChat <- R6::R6Class(
     #'
     #' @param width Width of the sidebar in pixels. Default is 400.
     #' @param height Height of the sidebar. Default is "100%".
+    #' @param fillable Whether the sidebar should be fillable. Default is `TRUE`.
     #' @param ... Additional arguments passed to [bslib::sidebar()].
     #'
     #' @return A [bslib::sidebar()] UI component.
@@ -396,10 +397,11 @@ QueryChat <- R6::R6Class(
     #'   # Main content here
     #' )
     #' }
-    sidebar = function(width = 400, height = "100%", ...) {
+    sidebar = function(width = 400, height = "100%", fillable = TRUE, ...) {
       bslib::sidebar(
         width = width,
         height = height,
+        fillable = fillable,
         class = "querychat-sidebar",
         ...,
         self$ui()
diff --git a/pkg-r/man/QueryChat.Rd b/pkg-r/man/QueryChat.Rd
index 7e72d1b0..ef747a96 100644
--- a/pkg-r/man/QueryChat.Rd
+++ b/pkg-r/man/QueryChat.Rd
@@ -414,7 +414,7 @@ Create a sidebar containing the querychat UI.
 This method generates a \code{\link[bslib:sidebar]{bslib::sidebar()}} component containing the chat
 interface, suitable for use with \code{\link[bslib:page_sidebar]{bslib::page_sidebar()}} or similar layouts.
 \subsection{Usage}{
-\if{html}{\out{<div class="r">}}\preformatted{QueryChat$sidebar(width = 400, height = "100\%", ...)}\if{html}{\out{</div>}}
+\if{html}{\out{<div class="r">}}\preformatted{QueryChat$sidebar(width = 400, height = "100\%", fillable = TRUE, ...)}\if{html}{\out{</div>}}
 }
 
 \subsection{Arguments}{
@@ -424,6 +424,8 @@ interface, suitable for use with \code{\link[bslib:page_sidebar]{bslib::page_sid
 
 \item{\code{height}}{Height of the sidebar. Default is "100\%".}
 
+\item{\code{fillable}}{Whether the sidebar should be fillable. Default is \code{TRUE}.}
+
 \item{\code{...}}{Additional arguments passed to \code{\link[bslib:sidebar]{bslib::sidebar()}}.}
 }
 \if{html}{\out{</div>}}