diff --git a/CHANGELOG.md b/CHANGELOG.md
index 52aa5a9..5496fa2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,14 @@
 
 ## Unreleased
 
+### New Features
+
+- feat: Add the `cell-output` option. The output of an executed cell is no longer framed, and `cell-output: true` frames it again. (#39)
+
+### Bug Fixes
+
+- fix: Remove the internal `code-window-auto-label` attribute from the rendered document.
+
 ## 1.3.3 (2026-08-02)
 
 ### Refactoring
diff --git a/_extensions/code-window/_modules/cell-output.lua b/_extensions/code-window/_modules/cell-output.lua
new file mode 100644
index 0000000..ebc5ee3
--- /dev/null
+++ b/_extensions/code-window/_modules/cell-output.lua
@@ -0,0 +1,57 @@
+--- @module "cell-output"
+--- @license MIT
+--- @copyright 2026 Mickaël Canouil
+--- @author Mickaël Canouil
+--- @brief Mark the code blocks that hold the output of an executed cell.
+--- @description Quarto puts the result of an executed cell in a Div with the
+--- `cell-output` classes, and the code block inside carries no language class.
+--- A CodeBlock filter sees that block on its own and cannot tell it apart from
+--- a fenced block written without a language. This pass marks it while the
+--- parent Div is still in reach, so the language and window passes can leave it
+--- alone.
+
+local M = {}
+
+local MARKER = 'code-window-cell-output'
+
+--- Check whether a Div holds the output of an executed cell.
+--- @param div pandoc.Div
+--- @return boolean
+local function is_cell_output(div)
+  for _, class in ipairs(div.classes) do
+    if class == 'cell-output' or class:match('^cell%-output%-') then
+      return true
+    end
+  end
+  return false
+end
+
+--- Mark every code block inside a cell-output Div.
+--- @param div pandoc.Div
+--- @return pandoc.Div|nil Marked Div, or nil when the Div is left as it is
+function M.Div(div)
+  if not is_cell_output(div) then
+    return nil
+  end
+  return div:walk({
+    CodeBlock = function(block)
+      block.attributes[MARKER] = 'true'
+      return block
+    end,
+  })
+end
+
+--- Check whether a code block holds the output of an executed cell.
+--- @param block pandoc.CodeBlock
+--- @return boolean
+function M.is_marked(block)
+  return block.attributes[MARKER] == 'true'
+end
+
+--- Remove the marker, so it never reaches the output document.
+--- @param block pandoc.CodeBlock
+function M.strip(block)
+  block.attributes[MARKER] = nil
+end
+
+return M
diff --git a/_extensions/code-window/_modules/language.lua b/_extensions/code-window/_modules/language.lua
index a769346..59bdeef 100644
--- a/_extensions/code-window/_modules/language.lua
+++ b/_extensions/code-window/_modules/language.lua
@@ -4,6 +4,9 @@
 --- @author Mickaël Canouil
 --- @brief Normalise code blocks with no or unknown language class.
 
+local cell_output = require(
+  quarto.utils.resolve_path('_modules/cell-output.lua'):gsub('%.lua$', ''))
+
 local M = {}
 
 local known_language_cache = {}
@@ -34,9 +37,14 @@ end
 --- keeps its original token as the label. The label is carried on the
 --- `code-window-auto-label` attribute (not `filename`, which is reserved for
 --- author-set filenames) and consumed by the auto-filename windowing path.
+--- The output of an executed cell is left as Quarto wrote it.
 --- @param block pandoc.CodeBlock
---- @return pandoc.CodeBlock
+--- @return pandoc.CodeBlock|nil
 function M.CodeBlock(block)
+  if cell_output.is_marked(block) then
+    return nil
+  end
+
   if not block.classes or #block.classes == 0 then
     block.classes:insert('default')
     if not block.attributes['filename'] or block.attributes['filename'] == '' then
diff --git a/_extensions/code-window/_schema.yml b/_extensions/code-window/_schema.yml
index 66c0d10..41bbfb4 100644
--- a/_extensions/code-window/_schema.yml
+++ b/_extensions/code-window/_schema.yml
@@ -14,6 +14,10 @@ options:
     enum: ["default", "macos", "windows"]
     default: "macos"
     description: "Window decoration style: 'macos' (traffic lights), 'windows' (title bar buttons), or 'default' (plain filename). Can be overridden per block with the 'code-window-style' attribute."
+  cell-output:
+    type: boolean
+    default: false
+    description: "Frame the output of an executed cell like a code block. Off by default, so output keeps the shape Quarto gives it."
   wrapper:
     type: string
     default: "code-window"
diff --git a/_extensions/code-window/code-window.lua b/_extensions/code-window/code-window.lua
index 87ae7a4..1523271 100644
--- a/_extensions/code-window/code-window.lua
+++ b/_extensions/code-window/code-window.lua
@@ -17,6 +17,7 @@ local log = require(quarto.utils.resolve_path('_modules/logging.lua'):gsub('%.lu
 local meta_mod = require(quarto.utils.resolve_path('_modules/metadata.lua'):gsub('%.lua$', ''))
 local pdoc = require(quarto.utils.resolve_path('_modules/pandoc-helpers.lua'):gsub('%.lua$', ''))
 local html_mod = require(quarto.utils.resolve_path('_modules/html.lua'):gsub('%.lua$', ''))
+local cell_output = require(quarto.utils.resolve_path('_modules/cell-output.lua'):gsub('%.lua$', ''))
 local code_annotations = nil
 
 -- ============================================================================
@@ -27,6 +28,7 @@ local code_annotations = nil
 --- @field enabled boolean Whether code-window styling is enabled
 --- @field auto_filename boolean Whether to auto-generate filename from language
 --- @field style string Window decoration style ('macos', 'windows', 'default')
+--- @field cell_output boolean Whether the output of an executed cell is framed
 --- @field typst_wrapper string Typst wrapper function name
 --- @field hotfix_code_annotations boolean Whether to apply the code-annotations hot-fix for Typst
 --- @field hotfix_skylighting boolean Whether to apply the Skylighting hot-fix for Typst
@@ -37,6 +39,7 @@ local DEFAULTS = {
   ['enabled'] = 'true',
   ['auto-filename'] = 'true',
   ['style'] = 'macos',
+  ['cell-output'] = 'false',
   ['wrapper'] = 'code-window',
   ['collapse'] = 'false',
   ['lines-label'] = 'true',
@@ -60,6 +63,18 @@ local CONFIG = nil
 local TYPST_BG_COLOUR = nil
 local ANNOTATION_BLOCK_COUNTER = 0
 
+-- ============================================================================
+-- CELL OUTPUT
+-- ============================================================================
+
+--- Check whether a block holds the output of an executed cell that the engine
+--- did not name. Such a block keeps the shape Quarto gave it.
+--- @param block pandoc.CodeBlock Code block element
+--- @return boolean
+local function is_unnamed_cell_output(block)
+  return cell_output.is_marked(block) and str.is_empty(block.attributes['filename'])
+end
+
 -- ============================================================================
 -- BLOCK-LEVEL STYLE OVERRIDE
 -- ============================================================================
@@ -480,6 +495,12 @@ end
 --- @param block pandoc.CodeBlock Code block element
 --- @return pandoc.Div|pandoc.CodeBlock Wrapped block or original
 local function process_html(block)
+  -- Default/unknown/no-language blocks carry their label on
+  -- code-window-auto-label (set by the language module). Read it here so no
+  -- return path can leak it into the rendered document.
+  local auto_label = block.attributes['code-window-auto-label']
+  block.attributes['code-window-auto-label'] = nil
+
   -- Per-block opt-out: code-window-enabled="false" skips window chrome.
   local block_enabled = block.attributes['code-window-enabled']
   if block_enabled then
@@ -520,11 +541,8 @@ local function process_html(block)
     return block
   end
 
-  -- Default/unknown/no-language blocks carry their label on
-  -- code-window-auto-label (set by the language module); everything else uses
-  -- its language class.
-  local filename = block.attributes['code-window-auto-label'] or block.classes[1]
-  block.attributes['code-window-auto-label'] = nil
+  -- Blocks with a language of their own are labelled with its class.
+  local filename = auto_label or block.classes[1]
 
   -- Set the filename attribute so Quarto creates its own .code-with-filename
   -- wrapper. This preserves the CodeBlock+OrderedList sibling structure
@@ -635,7 +653,9 @@ function Meta(meta)
   CURRENT_FORMAT = pdoc.get_quarto_format()
   local opts = meta_mod.get_options({
     extension = EXTENSION_NAME,
-    keys = { 'enabled', 'auto-filename', 'style', 'wrapper', 'collapse', 'lines-label' },
+    keys = {
+      'enabled', 'auto-filename', 'style', 'cell-output', 'wrapper', 'collapse', 'lines-label',
+    },
     meta = meta,
     defaults = DEFAULTS,
   })
@@ -698,6 +718,7 @@ function Meta(meta)
     enabled = opts['enabled'] == 'true',
     auto_filename = opts['auto-filename'] == 'true',
     style = VALID_STYLES[opts['style']] and opts['style'] or 'macos',
+    cell_output = opts['cell-output'] == 'true',
     typst_wrapper = opts['wrapper'],
     collapse = global_collapse,
     lines_label = opts['lines-label'] == 'true',
@@ -746,8 +767,20 @@ end
 --- Process CodeBlock elements for HTML/Reveal.js only.
 --- Typst processing is handled by the Blocks filter.
 function CodeBlock(block)
+  -- The Typst path reads the marker in the Pandoc filter, which runs first, so
+  -- this pass is where it is removed for every format.
+  local is_plain_output = is_unnamed_cell_output(block)
+  if cell_output.is_marked(block) then
+    cell_output.strip(block)
+  end
+
   if not CURRENT_FORMAT or not CONFIG or not CONFIG.enabled then
     block.attributes['code-window-no-auto-filename'] = nil
+    block.attributes['code-window-auto-label'] = nil
+    return block
+  end
+
+  if is_plain_output then
     return block
   end
 
@@ -767,7 +800,6 @@ end
 --- @return string|nil filename
 --- @return boolean is_auto
 --- @return string|nil block_style
---- @return boolean window_opted_out True when code-window-enabled="false" was set
 --- @return string|nil lines_label Highlighted-lines spec for the title bar
 local function resolve_window_params(block)
   -- Per-block opt-out: code-window-enabled="false" skips window chrome.
@@ -776,7 +808,7 @@ local function resolve_window_params(block)
     block.attributes['code-window-enabled'] = nil
   end
   if block_enabled == 'false' then
-    return nil, false, nil, true, nil
+    return nil, false, nil, nil
   end
 
   local block_style = read_block_style(block)
@@ -803,7 +835,7 @@ local function resolve_window_params(block)
     lines_label = read_block_lines_label(block)
   end
 
-  return filename, is_auto, block_style, false, lines_label
+  return filename, is_auto, block_style, lines_label
 end
 
 --- Process a single CodeBlock for Typst, returning replacement blocks.
@@ -814,7 +846,13 @@ end
 --- @return boolean consumed_next Whether the next block was consumed
 --- @return integer|nil annotation_block_id Block ID if annotations were found (for parent propagation)
 local function process_typst_block(block, next_block)
-  local filename, is_auto, block_style, window_opted_out, lines_label = resolve_window_params(block)
+  -- The output of an executed cell keeps the shape Quarto gave it, annotations
+  -- included, unless the engine gave it a filename of its own.
+  if is_unnamed_cell_output(block) then
+    return { block }, false, nil
+  end
+
+  local filename, is_auto, block_style, lines_label = resolve_window_params(block)
   local has_window = filename and filename ~= ''
   local effective_style = block_style or CONFIG.style
 
diff --git a/_extensions/code-window/main.lua b/_extensions/code-window/main.lua
index 44e1498..25b61da 100644
--- a/_extensions/code-window/main.lua
+++ b/_extensions/code-window/main.lua
@@ -12,6 +12,9 @@ local log = require(quarto.utils.resolve_path('_modules/logging.lua'):gsub('%.lu
 -- LOAD SUBMODULES
 -- ============================================================================
 
+local cell_output = require(
+  quarto.utils.resolve_path('_modules/cell-output.lua'):gsub('%.lua$', ''))
+
 local language = require(
   quarto.utils.resolve_path('_modules/language.lua'):gsub('%.lua$', ''))
 
@@ -23,6 +26,26 @@ local code_window = require(
 
 code_window.set_code_annotations(code_annotations)
 
+-- ============================================================================
+-- CELL OUTPUT
+-- ============================================================================
+
+--- Mark the code blocks that hold the output of an executed cell, so the later
+--- passes leave them as Quarto wrote them. Reads the configuration once and
+--- walks the document only when the output has to stay unframed. The language
+--- pass runs whether the extension is on or off, so the mark is set in both
+--- cases; the window passes remove it either way.
+--- @param doc pandoc.Pandoc
+--- @return pandoc.Pandoc|nil Marked document, or nil when the pass is skipped
+local function mark_cell_output(doc)
+  local config = code_window.CONFIG()
+  if not config or (config.enabled and config.cell_output) then
+    return nil
+  end
+  doc.blocks = doc.blocks:walk({ Div = cell_output.Div })
+  return doc
+end
+
 -- ============================================================================
 -- SKYLIGHTING HOT-FIX
 -- ============================================================================
@@ -49,9 +72,12 @@ end
 -- FILTER ASSEMBLY
 -- ============================================================================
 
+-- Meta runs first because the cell-output pass needs the configuration, and
+-- that pass runs before the language pass so a marked block is never relabelled.
 local filters = {
-  { CodeBlock = language.CodeBlock },
   { Meta = code_window.Meta },
+  { Pandoc = mark_cell_output },
+  { CodeBlock = language.CodeBlock },
   { Pandoc = code_window.Pandoc },
   { CodeBlock = code_window.CodeBlock },
 }
diff --git a/docs/reference.qmd b/docs/reference.qmd
index 6b66f21..27720df 100644
--- a/docs/reference.qmd
+++ b/docs/reference.qmd
@@ -18,6 +18,7 @@ extensions:
   code-window:
     style: macos
     auto-filename: true
+    cell-output: false
     collapse: false
     lines-label: true
 ```
@@ -27,6 +28,7 @@ extensions:
 | `enabled` | boolean | `true` | Whether the filter runs at all. |
 | `style` | string | `macos` | The window chrome: `macos` for traffic lights, `windows` for title-bar buttons, `default` for a plain filename. |
 | `auto-filename` | boolean | `true` | Use the block's language as the filename when none is given. |
+| `cell-output` | boolean | `false` | Frame the output of an executed cell as well as its source. |
 | `collapse` | boolean or string | `false` | Wrap every block in a `<details>`. `open` renders it expanded, `closed` or `true` collapsed. HTML only. |
 | `lines-label` | boolean | `true` | Show a chip beside the filename with the highlighted-line spec. |
 | `wrapper` | string | `code-window` | The Typst function used to draw the chrome. |
@@ -60,6 +62,23 @@ The result is the same window; it needs JavaScript, as the rest of the HTML chro
 Typst frames derived and author-set filenames alike, without a script.
 :::
 
+## Executed cells
+
+Quarto writes the output of an executed cell as a code block with no language.
+That block keeps the shape Quarto gives it: no chrome, and no derived filename.
+Only the source of the cell is framed.
+
+Set `cell-output` to `true` to frame the output as well.
+
+```yaml
+extensions:
+  code-window:
+    cell-output: true
+```
+
+An engine can put a filename on the output block, through knitr's `attr-output` for example.
+Output named that way is always framed, whatever this option says.
+
 ## How the chrome is applied
 
 In HTML the extension marks blocks and injects a stylesheet and a script.