diff --git a/frontend/components/Cell.js b/frontend/components/Cell.js
index 615b4b8fe..23891319d 100644
--- a/frontend/components/Cell.js
+++ b/frontend/components/Cell.js
@@ -105,7 +105,19 @@ const on_jump = (hasBarrier, pluto_actions, cell_id) => () => {
  * */
 export const Cell = ({
     cell_input: { cell_id, code, code_folded, metadata },
-    cell_result: { queued, running, runtime, errored, output, logs, published_object_keys, depends_on_disabled_cells, depends_on_skipped_cells },
+    cell_result: {
+        queued,
+        running,
+        runtime,
+        errored,
+        output,
+        logs,
+        published_object_keys,
+        depends_on_disabled_cells,
+        depends_on_skipped_cells,
+        stale,
+        depends_on_stale_cells,
+    },
     cell_dependencies,
     cell_input_local,
     notebook_id,
@@ -294,8 +306,10 @@ export const Cell = ({
                 code_folded,
                 skip_as_script,
                 running_disabled,
+                stale,
                 depends_on_disabled_cells,
                 depends_on_skipped_cells,
+                depends_on_stale_cells,
                 show_input,
                 shrunk: Object.values(logs).length > 0,
                 hooked_up: output?.has_pluto_hook_features ?? false,
@@ -315,9 +329,42 @@ export const Cell = ({
                 <span></span>
             </button>
             <pluto-shoulder draggable="true" title="Drag to move cell">
-                <button onClick=${on_code_fold} class="foldcode" title="Show/hide code">
-                    <span></span>
-                </button>
+                <div>
+                    <button onClick=${on_code_fold} class="foldcode" title="Show/hide code">
+                        <span></span>
+                    </button>
+                    ${stale
+                        ? html`<button
+                              class="stale_cell_marker"
+                              title=${`This cell’s output is stale. Click to know more!`}
+                              onClick=${(e) => {
+                                  open_pluto_popup({
+                                      type: "info",
+                                      source_element: e.target,
+                                      body: html`This cell’s outputs is wrapped in a PlutoRunner.Stale object. This freezes all the cells that depend on this
+                                      one.`,
+                                  })
+                              }}
+                          >
+                              <span></span>
+                          </button>`
+                        : depends_on_stale_cells
+                        ? html`<button
+                              class="depends_on_stale_cells_marker"
+                              title=${`This cell depends on stale cells. Click to know more!`}
+                              onClick=${(e) => {
+                                  open_pluto_popup({
+                                      type: "info",
+                                      source_element: e.target,
+                                      body: html`This cell depends on a cell whose outputs is wrapped in a PlutoRunner.Stale object. This freezes all the cells
+                                      that depend on it, including this one.`,
+                                  })
+                              }}
+                          >
+                              <span></span>
+                          </button>`
+                        : null}
+                </div>
             </pluto-shoulder>
             <pluto-trafficlight></pluto-trafficlight>
             ${code_not_trusted_yet
diff --git a/frontend/components/Editor.js b/frontend/components/Editor.js
index 2afb63b4e..72cfa94f5 100644
--- a/frontend/components/Editor.js
+++ b/frontend/components/Editor.js
@@ -118,7 +118,7 @@ const first_true_key = (obj) => {
  * @type {{
  *    disabled: boolean,
  *    show_logs: boolean,
- *    skip_as_script: boolean
+ *    skip_as_script: boolean,
  *  }}
  *
  * @typedef CellInputData
@@ -160,12 +160,14 @@ const first_true_key = (obj) => {
  *  queued: boolean,
  *  running: boolean,
  *  errored: boolean,
+ *  stale: boolean,
  *  runtime: number?,
  *  downstream_cells_map: { string: [string]},
  *  upstream_cells_map: { string: [string]},
  *  precedence_heuristic: number?,
  *  depends_on_disabled_cells: boolean,
  *  depends_on_skipped_cells: boolean,
+ *  depends_on_stale_cells: boolean,
  *  output: {
  *      body: string,
  *      persist_js_state: boolean,
diff --git a/frontend/editor.css b/frontend/editor.css
index dac3fc711..5b601a58b 100644
--- a/frontend/editor.css
+++ b/frontend/editor.css
@@ -1253,6 +1253,11 @@ pluto-display > div {
     display: none;
 }
 
+/* STALE CELLS */
+pluto-cell.stale > pluto-output {
+    background: var(--pluto-stale-output-bg-color);
+}
+
 /* DISABLED CELLS */
 
 pluto-cell.depends_on_disabled_cells > pluto-output,
@@ -1390,7 +1395,7 @@ button.floating_back_button,
 pluto-cell > button,
 pluto-input > button,
 pluto-runarea > button,
-pluto-shoulder > button,
+pluto-shoulder > div > button,
 nav#slide_controls > button {
     position: absolute;
     margin: 0px;
@@ -1420,7 +1425,6 @@ pluto-shoulder {
     --invisible-border: calc(0.5 * var(--pluto-cell-spacing));
     --shoulder-width: calc(28px + var(--invisible-border));
     --border-radius: calc(5px + var(--invisible-border));
-
     left: calc(0px - var(--shoulder-width));
     width: var(--shoulder-width);
     border-radius: var(--border-radius) 0px 0px var(--border-radius);
@@ -1434,6 +1438,7 @@ pluto-shoulder {
     bottom: calc(0px - var(--invisible-border));
     border: var(--invisible-border) solid rgba(0, 0, 0, 0);
     border-right: none;
+    overflow: clip;
 }
 pluto-editor.fullscreen pluto-shoulder {
     --shoulder-width: 2000px;
@@ -1444,32 +1449,44 @@ pluto-shoulder:hover {
     background-clip: padding-box;
 }
 
-pluto-shoulder > button {
+pluto-shoulder > div {
     flex: 0 0 auto;
     position: sticky;
     top: 0;
+    display: flex;
+    flex-direction: column;
+}
+
+pluto-shoulder > div > button {
+    position: static;
     padding: 4px 5px 4px 10px;
 }
 
-pluto-cell:focus-within > pluto-shoulder > button {
+pluto-cell:focus-within > pluto-shoulder > div > button {
     /* we use padding instead of 4px extra margin to move the eye to the left so that the hitbox becomes grows - you want to be able to double click the button */
     padding-right: 9px;
 }
 
-/* pluto-cell.code_folded.inline-output > pluto-shoulder > button {
+/* pluto-cell.code_folded.inline-output > pluto-shoulder > div > button {
     margin-top: 3px;
 } */
 
-pluto-shoulder > button > span::after {
+pluto-shoulder > div > button.foldcode > span::after {
     background-image: url("https://cdn.jsdelivr.net/gh/ionic-team/ionicons@5.5.1/src/svg/eye-outline.svg");
     filter: var(--image-filters);
 }
 
-pluto-cell.code_folded > pluto-shoulder > button > span::after {
+pluto-cell.code_folded > pluto-shoulder > div > button.foldcode > span::after {
     background-image: url("https://cdn.jsdelivr.net/gh/ionic-team/ionicons@5.5.1/src/svg/eye-off-outline.svg");
     filter: var(--image-filters);
 }
 
+pluto-shoulder > div > button.stale_cell_marker > span::after,
+pluto-shoulder > div > button.depends_on_stale_cells_marker > span::after {
+    background-image: url("https://cdn.jsdelivr.net/gh/ionic-team/ionicons@5.5.1/src/svg/warning-outline.svg");
+    filter: var(--image-filters);
+}
+
 /* TRAFFIC LIGHT */
 
 pluto-trafficlight {
@@ -1548,6 +1565,14 @@ body:not(.___) pluto-cell.errored > pluto-trafficlight {
     background-clip: padding-box;
 }
 
+/* stale cells */
+body:not(.___) pluto-cell.stale > pluto-trafficlight,
+body:not(.___) pluto-cell.depends_on_stale_cells > pluto-trafficlight {
+    background: var(--stale-cell-color);
+    border-left-color: var(--stale-cell-color);
+    background-clip: padding-box;
+}
+
 body:not(.___) pluto-cell.queued > pluto-trafficlight::after {
     background: repeating-linear-gradient(-45deg, rgba(0, 0, 0, 0), rgba(0, 0, 0, 0) 8px, var(--normal-cell-color) 8px, var(--normal-cell-color) 16px);
     background-clip: padding-box;
@@ -1624,7 +1649,7 @@ pluto-input > button > span {
     pluto-cell > button,
     pluto-input > button,
     pluto-runarea > button,
-    pluto-shoulder > button,
+    pluto-shoulder > div > button,
     pluto-cell > pluto-runarea {
         opacity: 0;
         /* to make it feel smooth: */
@@ -1638,8 +1663,8 @@ pluto-input > button > span {
     pluto-cell:hover > pluto-input > button,
     pluto-cell:focus-within > pluto-input > button,
     pluto-cell > pluto-runarea > button,
-    pluto-cell:hover > pluto-shoulder > button,
-    pluto-cell:focus-within > pluto-shoulder > button {
+    pluto-cell:hover > pluto-shoulder > div > button,
+    pluto-cell:focus-within > pluto-shoulder > div > button {
         opacity: 0.6;
         transition: opacity 0.25s ease-in-out;
     }
@@ -1650,7 +1675,7 @@ pluto-input > button > span {
     pluto-cell > button:hover,
     pluto-cell > pluto-input > button:hover,
     pluto-cell > pluto-runarea > button:hover,
-    pluto-cell > pluto-shoulder > button:hover,
+    pluto-cell > pluto-shoulder > div > button:hover,
     pluto-cell:hover > pluto-runarea {
         opacity: 1;
         /* to make it feel snappy: */
@@ -1661,7 +1686,7 @@ pluto-input > button > span {
 @media screen and (pointer: coarse) {
     pluto-cell > button.add_cell,
     pluto-input > button,
-    pluto-shoulder > button {
+    pluto-shoulder > div > button {
         opacity: 0.25;
         transition: opacity 0.25s ease-in-out;
     }
@@ -1676,14 +1701,14 @@ pluto-input > button > span {
     pluto-cell:focus-within > button.add_cell,
     pluto-cell:focus-within > pluto-input > button,
     pluto-cell:focus-within > pluto-runarea,
-    pluto-cell:focus-within > pluto-shoulder > button {
+    pluto-cell:focus-within > pluto-shoulder > div > button {
         opacity: 0.6;
         transition: opacity 0.25s ease-in-out;
     }
     pluto-cell > pluto-input > button:focus-within,
     pluto-cell > button:focus-within,
     pluto-cell > pluto-input > button:focus-within pluto-cell > pluto-runarea > button:focus-within,
-    pluto-cell > pluto-shoulder > button:focus-within,
+    pluto-cell > pluto-shoulder > div > button:focus-within,
     pluto-cell > pluto-runarea {
         opacity: 1;
         /* to make it feel snappy: */
@@ -1694,7 +1719,7 @@ pluto-input > button > span {
 pluto-cell > button > span::after,
 pluto-input > button > span::after,
 pluto-runarea > button > span::after,
-pluto-shoulder > button > span::after {
+pluto-shoulder > div > button > span::after {
     display: block;
     content: " " !important;
     background-size: 17px 17px;
diff --git a/frontend/themes/dark.css b/frontend/themes/dark.css
index d72c9ea39..b3b14b309 100644
--- a/frontend/themes/dark.css
+++ b/frontend/themes/dark.css
@@ -23,6 +23,7 @@
         --error-cell-color: rgba(var(--error-color), 0.6);
         --bright-error-cell-color: rgba(var(--error-color), 0.9);
         --light-error-cell-color: rgba(var(--error-color), 0);
+        --stale-cell-color: #b86f00;
 
         /*Export styling*/
         --export-bg-color: hsl(225deg 17% 18%);
@@ -45,6 +46,7 @@
         --pluto-output-color: hsl(0deg 0% 77%);
         --pluto-output-h-color: hsl(0, 0%, 90%);
         --pluto-output-bg-color: var(--main-bg-color);
+        --pluto-stale-output-bg-color: #332300;
         --a-underline: #ffffff69;
         --blockquote-color: inherit;
         --blockquote-bg: #2e2e2e;
diff --git a/frontend/themes/light.css b/frontend/themes/light.css
index c1bd8b4f0..4a4dd51ed 100644
--- a/frontend/themes/light.css
+++ b/frontend/themes/light.css
@@ -23,6 +23,7 @@
         --error-cell-color: rgba(var(--error-color), 0.7);
         --bright-error-cell-color: rgb(var(--error-color));
         --light-error-cell-color: rgba(var(--error-color), 0.05);
+        --stale-cell-color: #ffba53;
 
         /*Export styling*/
         --export-bg-color: rgb(60, 67, 101);
@@ -45,6 +46,7 @@
         --pluto-output-color: hsl(0, 0%, 25%);
         --pluto-output-h-color: hsl(0, 0%, 12%);
         --pluto-output-bg-color: white;
+        --pluto-stale-output-bg-color: #ffeed5;
         --a-underline: #00000059;
         --blockquote-color: #555;
         --blockquote-bg: #f2f2f2;
@@ -191,36 +193,36 @@
 
         /* code highlighting */
         --cm-color-editor-text: #41323f;
-        --cm-color-comment:     #e96ba8;
-        --cm-color-atom:        #815ba4;
-        --cm-color-number:      #815ba4;
-        --cm-color-property:    #b67a48;
-        --cm-color-keyword:     #ef6155;
-        --cm-color-string:      #da5616;
-        --cm-color-var:         #5668a4;
-        --cm-color-var2:        #37768a;
-        --cm-color-macro:       #5c8c5f;
-        --cm-color-builtin:     #5e7ad3;
-        --cm-color-function:    #cc80ac;
-        --cm-color-type:        hsl(170deg 7% 56%);
-        --cm-color-bracket:     #41323f;
-        --cm-color-tag:         #ef6155;
-        --cm-color-link:        #815ba4;
-        --cm-color-error-bg:    #ef6155;
-        --cm-color-error:       #f7f7f7;
+        --cm-color-comment: #e96ba8;
+        --cm-color-atom: #815ba4;
+        --cm-color-number: #815ba4;
+        --cm-color-property: #b67a48;
+        --cm-color-keyword: #ef6155;
+        --cm-color-string: #da5616;
+        --cm-color-var: #5668a4;
+        --cm-color-var2: #37768a;
+        --cm-color-macro: #5c8c5f;
+        --cm-color-builtin: #5e7ad3;
+        --cm-color-function: #cc80ac;
+        --cm-color-type: hsl(170deg 7% 56%);
+        --cm-color-bracket: #41323f;
+        --cm-color-tag: #ef6155;
+        --cm-color-link: #815ba4;
+        --cm-color-error-bg: #ef6155;
+        --cm-color-error: #f7f7f7;
         --cm-color-matchingBracket: black;
         --cm-color-matchingBracket-bg: #1b4bbb21;
         --cm-color-placeholder-text: rgba(0, 0, 0, 0.2);
         --cm-color-clickable-underline: #ced2ef;
 
         /* Mixed parsers */
-        --cm-color-html:        #48b685;
+        --cm-color-html: #48b685;
         --cm-color-html-accent: #00ab85;
-        --cm-color-css:         #876800;
-        --cm-color-css-accent:  #696200;
+        --cm-color-css: #876800;
+        --cm-color-css-accent: #696200;
         --cm-css-why-doesnt-codemirror-highlight-all-the-text-aaa: #3b3700;
-        --cm-color-md:          #005a9b;
-        --cm-color-md-accent:   #00a9d1;
+        --cm-color-md: #005a9b;
+        --cm-color-md-accent: #00a9d1;
 
         /*autocomplete menu*/
         --autocomplete-menu-bg-color: white;
diff --git a/src/evaluation/Run.jl b/src/evaluation/Run.jl
index ae1d22357..43bc6383d 100644
--- a/src/evaluation/Run.jl
+++ b/src/evaluation/Run.jl
@@ -75,6 +75,8 @@ function run_reactive_core!(
     # find (indirectly) skipped-as-script cells and update their status
     update_skipped_cells_dependency!(notebook, new_topology)
 
+	update_stale_cell_dependents!(notebook, new_topology)
+
     removed_cells = setdiff(all_cells(old_topology), all_cells(new_topology))
     roots = vcat(roots, removed_cells)
 
@@ -182,22 +184,29 @@ function run_reactive_core!(
 
         if (skip = any_interrupted || notebook.wants_to_interrupt || !will_run_code(notebook))
             relay_reactivity_error!(cell, InterruptException())
-        else
-            run = run_single!(
-                (session, notebook), cell,
-                new_topology.nodes[cell], new_topology.codes[cell];
-                user_requested_run = (user_requested_run && cell ∈ roots),
-                capture_stdout = session.options.evaluation.capture_stdout,
-            )
-            any_interrupted |= run.interrupted
-
-            # Support one bond defining another when setting both simultaneously in PlutoSliderServer
-            # https://github.com/fonsp/Pluto.jl/issues/1695
-
-            # set the redefined bound variables to their original value from the request
-            defs = notebook.topology.nodes[cell].definitions
-            set_bond_value_pairs!(session, notebook, Iterators.filter(((sym,val),) -> sym ∈ defs, bond_value_pairs))
-        end
+		elseif !(skip = cell.depends_on_stale_cells)
+			was_stale = cell.stale
+		
+			run = run_single!(
+				(session, notebook), cell,
+				new_topology.nodes[cell], new_topology.codes[cell];
+				user_requested_run=(user_requested_run && cell ∈ roots),
+				capture_stdout=session.options.evaluation.capture_stdout,
+			)
+			any_interrupted |= run.interrupted
+		
+			# Support one bond defining another when setting both simultaneously in PlutoSliderServer
+			# https://github.com/fonsp/Pluto.jl/issues/1695
+		
+			# set the redefined bound variables to their original value from the request
+			defs = notebook.topology.nodes[cell].definitions
+			set_bond_value_pairs!(session, notebook, Iterators.filter(((sym, val),) -> sym ∈ defs, bond_value_pairs))
+			
+			# stale status changed
+			if was_stale != run.stale
+				update_stale_cell_dependents!(notebook, new_topology)
+			end
+		end
 
         cell.running = false
 		Status.report_business_finished!(cell_status, Symbol(i), !skip && !run.errored)
@@ -331,7 +340,8 @@ function set_output!(cell::Cell, run, expr_cache::ExprAnalysisCache; persist_js_
 		end
 		new_published
 	end
-	
+
+	cell.stale = run.stale
 	cell.runtime = run.runtime
 	cell.errored = run.errored
 	cell.running = cell.queued = false
@@ -340,7 +350,8 @@ end
 function clear_output!(cell::Cell)
 	cell.output = CellOutput()
 	cell.published_objects = Dict{String,Any}()
-	
+
+	cell.stale = false
 	cell.runtime = nothing
 	cell.errored = false
 	cell.running = cell.queued = false
@@ -663,3 +674,38 @@ function update_disabled_cells_dependency!(notebook::Notebook, topology::Noteboo
         cell.depends_on_disabled_cells = true
     end
 end
+
+"""
+Find all runnable cells that depend on stale cells. This does not include the
+stale cells themselves unless they themselves depend on stale cells.
+"""
+function find_stale_cell_dependents(notebook::Notebook, topology::NotebookTopology=notebook.topology)::Set{Cell}
+    stack = collect(filter(stale, notebook.cells))
+    dependents = Set{Cell}()
+    # depth-first search
+    while !isempty(stack)
+        cell = pop!(stack)
+
+        cell_dependents = where_referenced(topology, cell)
+
+        new_dependents = setdiff(cell_dependents, dependents)
+        union!(dependents, new_dependents)
+        append!(stack, new_dependents)
+    end
+
+    dependents
+end
+
+"""
+Updates `depends_on_stale_cells` for the cells in the notebook. This does not include the
+stale cells themselves unless they themselves depend on stale cells.
+"""
+function update_stale_cell_dependents!(notebook::Notebook, topology::NotebookTopology=notebook.topology)
+    for cell in notebook.cells
+        cell.depends_on_stale_cells = false
+    end
+
+    for cell in find_stale_cell_dependents(notebook, topology)
+        cell.depends_on_stale_cells = true
+    end
+end
diff --git a/src/notebook/Cell.jl b/src/notebook/Cell.jl
index 5af2d4a27..6f263e47f 100644
--- a/src/notebook/Cell.jl
+++ b/src/notebook/Cell.jl
@@ -43,6 +43,7 @@ Base.@kwdef mutable struct Cell <: PlutoDependencyExplorer.AbstractCell
     output::CellOutput=CellOutput()
     queued::Bool=false
     running::Bool=false
+    stale::Bool=false
 
     published_objects::Dict{String,Any}=Dict{String,Any}()
     
@@ -56,6 +57,7 @@ Base.@kwdef mutable struct Cell <: PlutoDependencyExplorer.AbstractCell
 
     depends_on_disabled_cells::Bool=false
     depends_on_skipped_cells::Bool=false
+    depends_on_stale_cells::Bool=false
 
     metadata::Dict{String,Any}=copy(DEFAULT_CELL_METADATA)
 end
@@ -84,3 +86,4 @@ end
 can_show_logs(c::Cell) = get(c.metadata, METADATA_SHOW_LOGS_KEY, DEFAULT_CELL_METADATA[METADATA_SHOW_LOGS_KEY])
 is_skipped_as_script(c::Cell) = get(c.metadata, METADATA_SKIP_AS_SCRIPT_KEY, DEFAULT_CELL_METADATA[METADATA_SKIP_AS_SCRIPT_KEY])
 must_be_commented_in_file(c::Cell) = is_disabled(c) || is_skipped_as_script(c) || c.depends_on_disabled_cells || c.depends_on_skipped_cells
+stale(c::Cell) = c.stale
diff --git a/src/runner/PlutoRunner/src/PlutoRunner.jl b/src/runner/PlutoRunner/src/PlutoRunner.jl
index 4e449833a..f97b28d99 100644
--- a/src/runner/PlutoRunner/src/PlutoRunner.jl
+++ b/src/runner/PlutoRunner/src/PlutoRunner.jl
@@ -30,6 +30,9 @@ abstract type SpecialPlutoExprValue end
 struct GiveMeCellID <: SpecialPlutoExprValue end
 struct GiveMeRerunCellFunction <: SpecialPlutoExprValue end
 struct GiveMeRegisterCleanupFunction <: SpecialPlutoExprValue end
+struct Stale
+    out
+end
 
 
 # TODO: clear key when a cell is deleted furever
diff --git a/src/runner/PlutoRunner/src/display/format_output.jl b/src/runner/PlutoRunner/src/display/format_output.jl
index 672d5786b..8a62eeb49 100644
--- a/src/runner/PlutoRunner/src/display/format_output.jl
+++ b/src/runner/PlutoRunner/src/display/format_output.jl
@@ -14,7 +14,8 @@ const table_column_display_limit_increase = 30
 const tree_display_extra_items = Dict{UUID,Dict{ObjectDimPair,Int64}}()
 
 # This is not a struct to make it easier to pass these objects between processes.
-const FormattedCellResult = NamedTuple{(:output_formatted, :errored, :interrupted, :process_exited, :runtime, :published_objects, :has_pluto_hook_features),Tuple{PlutoRunner.MimedOutput,Bool,Bool,Bool,Union{UInt64,Nothing},Dict{String,Any},Bool}}
+const FormattedCellResult = NamedTuple{(:output_formatted, :errored, :interrupted, :process_exited, :runtime, :published_objects, :has_pluto_hook_features, :stale),Tuple{PlutoRunner.MimedOutput,Bool,Bool,Bool,Union{UInt64,Nothing},Dict{String,Any},Bool,Bool}}
+
 
 function formatted_result_of(
     notebook_id::UUID, 
@@ -39,6 +40,7 @@ function formatted_result_of(
     has_pluto_hook_features = haskey(cell_expanded_exprs, cell_id) && cell_expanded_exprs[cell_id].has_pluto_hook_features
     ans = cell_results[cell_id]
     errored = ans isa CapturedException
+    stale = ans isa Stale
 
     output_formatted = if (!ends_with_semicolon || errored)
         with_logger_and_io_to_logs(get_cell_logger(notebook_id, cell_id); capture_stdout) do
@@ -70,6 +72,7 @@ function formatted_result_of(
         runtime = get(cell_runtimes, cell_id, nothing),
         published_objects,
         has_pluto_hook_features,
+        stale,
     )
 end
 
@@ -102,6 +105,7 @@ format_output(@nospecialize(x); context=default_iocontext) = format_output_defau
 
 format_output(::Nothing; context=default_iocontext) = ("", MIME"text/plain"())
 
+format_output((;out)::Stale; context=default_iocontext) = format_output(out; context)
 
 
 function format_output(binding::Base.Docs.Binding; context=default_iocontext)
diff --git a/src/webserver/Dynamic.jl b/src/webserver/Dynamic.jl
index 5960c0ff7..cda79d043 100644
--- a/src/webserver/Dynamic.jl
+++ b/src/webserver/Dynamic.jl
@@ -124,9 +124,11 @@ function notebook_to_js(notebook::Notebook)
                 "queued" => cell.queued,
                 "running" => cell.running,
                 "errored" => cell.errored,
+                "stale" => cell.stale,
                 "runtime" => cell.runtime,
                 "logs" => FirebaseyUtils.AppendonlyMarker(cell.logs),
                 "depends_on_skipped_cells" => cell.depends_on_skipped_cells,
+                "depends_on_stale_cells" => cell.depends_on_stale_cells,
             )
         for (id, cell) in notebook.cells_dict),
         "cell_order" => notebook.cell_order,
diff --git a/test/runtests.jl b/test/runtests.jl
index 83b2bae1b..c9066c6bc 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -45,6 +45,7 @@ verify_no_running_processes()
 @timeit_include("DependencyCache.jl")
 @timeit_include("Throttled.jl")
 @timeit_include("cell_disabling.jl")
+@timeit_include("stale_cells.jl")
 
 verify_no_running_processes()
 
diff --git a/test/stale_cells.jl b/test/stale_cells.jl
new file mode 100644
index 000000000..a7731fd18
--- /dev/null
+++ b/test/stale_cells.jl
@@ -0,0 +1,90 @@
+using Test
+using Pluto
+using Pluto: update_run!, ServerSession, Cell, Notebook, WorkspaceManager
+
+@testset "Stale cells" begin
+    🍭 = ServerSession()
+    🍭.options.evaluation.workspace_use_distributed = false
+
+    notebook = Notebook([
+        Cell("a = 1") # 1
+        Cell("b = a + 1") # 2
+
+        Cell("""
+        begin
+            c = b
+            push!(runs, a + 1)
+            b
+        end
+            """) # 3
+
+        Cell("a + 1") # 4
+
+        Cell("begin runs = [] end") # 5
+
+        Cell("length(runs)") # 6
+
+        Cell("c") # 7
+    ])
+    update_run!(🍭, notebook, notebook.cells)
+
+    id(i) = notebook.cells[i].cell_id
+    c(i) = notebook.cells[i]
+    get_depends_on_stale_cells(notebook::Notebook) = [i for (i, c) in pairs(notebook.cells) if c.depends_on_stale_cells]
+    get_stale_cells(notebook::Notebook) = [i for (i, c) in pairs(notebook.cells) if c.stale]
+
+    @test get_stale_cells(notebook) == []
+    @test get_depends_on_stale_cells(notebook) == []
+    @test all(noerror, notebook.cells)
+    @test c(6).output.body == "1"
+
+    # Cell metadata gets updated
+    setcode!(c(2), "begin b = a + 1; Main.PlutoRunner.Stale(Nothing) end")
+
+    update_run!(🍭, notebook, c(2))
+
+    @test get_stale_cells(notebook) == [2]
+    @test get_depends_on_stale_cells(notebook) == [3, 7]
+    @test all(noerror, notebook.cells)
+
+    # depends_on_stale_cells output does not change, but stale cells do
+    setcode!(c(2), "begin b = a + 2; Main.PlutoRunner.Stale(b) end")
+
+    update_run!(🍭, notebook, c(2))
+    update_run!(🍭, notebook, c(6))
+
+    @test get_stale_cells(notebook) == [2]
+    @test get_depends_on_stale_cells(notebook) == [3, 7]
+    @test c(3).output.body == "2"
+    @test c(2).output.body == "3"
+    @test all(noerror, notebook.cells)
+    @test c(6).output.body == "1"
+
+    setcode!(c(1), "a = 2")
+
+    update_run!(🍭, notebook, c(1))
+    update_run!(🍭, notebook, c(6))
+
+    @test get_stale_cells(notebook) == [2]
+    @test get_depends_on_stale_cells(notebook) == [3, 7]
+    @test c(3).output.body == "2"
+    @test c(2).output.body == "4"
+    @test c(7).output.body == "2"
+    @test all(noerror, notebook.cells)
+    @test c(6).output.body == "1"
+
+    # we can resume
+    setcode!(c(2), "begin b = a + 2; Nothing end")
+
+    update_run!(🍭, notebook, c(2))
+    update_run!(🍭, notebook, c(6))
+
+    @test get_stale_cells(notebook) == []
+    @test get_depends_on_stale_cells(notebook) == []
+    @test c(3).output.body == "4"
+    @test c(7).output.body == "4"
+    @test all(noerror, notebook.cells)
+    @test c(6).output.body == "2"
+
+    cleanup(🍭, notebook)
+end
\ No newline at end of file