improvement: additional print configuration, fix race conditions in export to pdf #8038

mscolnick · 2026-01-28T20:48:58Z

replace no-print for print:hidden (since this will also hide into when printing using Cmd+P)
fix race condition when capturing screenshots. there were a few here where: 1) old requests were not cancelled and could overwrite newer otuputs, 2) new request could get skipped if in the output did not change but already requested
remove snappy and always pass includeStyleProperties (otherwise we will get inconsistenties)
remove adding .printing on the body when just snapshotting the cell output

vercel · 2026-01-28T20:49:02Z

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Project	Deployment	Review	Updated (UTC)
marimo-docs	Ready	Preview, Comment	Jan 28, 2026 9:27pm

Copilot

Pull request overview

This pull request improves print configuration and fixes race conditions in PDF export functionality by introducing a new AsyncCaptureTracker for managing concurrent screenshot captures and migrating from a custom no-print CSS class to Tailwind's print:hidden utility class.

Changes:

Introduces AsyncCaptureTracker to prevent race conditions when taking screenshots of multiple cells concurrently
Removes the snappy parameter from screenshot functions, simplifying the API and always using optimized style properties
Migrates from custom no-print CSS class to Tailwind's print:hidden utility across all UI components
Removes reference counting mechanism for body.printing class in favor of scoped cleanup functions

Reviewed changes

Copilot reviewed 25 out of 25 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
frontend/src/utils/async-capture-tracker.ts	New utility class for tracking async capture operations with per-key abort signals and state management
frontend/src/utils/tests/async-capture-tracker.test.ts	Comprehensive test suite for AsyncCaptureTracker covering all state transitions and edge cases
frontend/src/core/export/hooks.ts	Integrates AsyncCaptureTracker to prevent duplicate/concurrent captures and handle in-flight waiters
frontend/src/core/export/tests/hooks.test.ts	Updates tests to remove snappy parameter and adds retry test for failed captures
frontend/src/utils/html-to-image.ts	Removes snappy parameter, always uses necessary style properties, updates filter to check for print:hidden class
frontend/src/utils/download.ts	Simplifies screenshot preparation by removing ref counting, exports ADD_PRINTING_CLASS helper
frontend/src/utils/tests/download.test.tsx	Removes tests for deprecated snappy parameter and ref counting logic
frontend/src/css/app/print.css	Removes custom no-print and printing-output CSS rules
frontend/src/components/ui/dropdown-menu.tsx	Adds print:hidden class to dropdown content
frontend/src/components/static-html/static-banner.tsx	Replaces no-print with print:hidden
frontend/src/components/home/components.tsx	Replaces no-print with print:hidden in tutorial dropdown
frontend/src/components/editor/renderers/vertical-layout/vertical-layout.tsx	Uses ADD_PRINTING_CLASS for notebook screenshots, updates class names
frontend/src/components/editor/actions/useNotebookActions.tsx	Uses ADD_PRINTING_CLASS and removes snappy parameter
frontend/src/components/editor/header/status.tsx	Replaces no-print with print:hidden
frontend/src/components/editor/file-tree/file-explorer.tsx	Replaces no-print with print:hidden
frontend/src/components/editor/controls/notebook-menu-dropdown.tsx	Replaces no-print with print:hidden
frontend/src/components/editor/controls/Controls.tsx	Replaces no-print with print:hidden (with duplicates)
frontend/src/components/editor/chrome/*	Multiple files replacing no-print with print:hidden across chrome UI elements
frontend/src/components/debug/indicator.tsx	Adds print:hidden to debug indicator
frontend/src/components/data-table/*	Multiple files with class name updates and data-testid issues

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Copilot · 2026-01-28T20:54:07Z

frontend/src/components/editor/renderers/vertical-layout/vertical-layout.tsx

      data-testid="notebook-actions-dropdown"
      className={cn(
-        "right-0 top-0 z-50 m-4 no-print flex gap-2 print:hidden",
+        "right-0 top-0 z-50 m-4 print:hidden flex gap-2 print:hidden",


The class "print:hidden" is duplicated in this className string. It appears twice: once at the beginning and once at the end. Remove one occurrence to avoid redundancy.

Suggested change

"right-0 top-0 z-50 m-4 print:hidden flex gap-2 print:hidden",

"right-0 top-0 z-50 m-4 print:hidden flex gap-2",

Copilot · 2026-01-28T20:54:07Z

frontend/src/components/editor/controls/Controls.tsx


 const topRightControls =
-  "absolute top-3 right-5 m-0 flex items-center gap-2 min-h-[28px] no-print pointer-events-auto z-30 print:hidden";
+  "absolute top-3 right-5 m-0 flex items-center gap-2 min-h-[28px] print:hidden pointer-events-auto z-30 print:hidden";


The class "print:hidden" is duplicated in this className string. It appears twice in the same line. Remove one occurrence to avoid redundancy.

Copilot · 2026-01-28T20:54:08Z

frontend/src/components/editor/controls/Controls.tsx


 const bottomRightControls =
-  "absolute bottom-5 right-5 flex flex-col gap-2 items-center no-print pointer-events-auto z-30 print:hidden";
+  "absolute bottom-5 right-5 flex flex-col gap-2 items-center print:hidden pointer-events-auto z-30 print:hidden";


The class "print:hidden" is duplicated in this className string. It appears twice in the same line. Remove one occurrence to avoid redundancy.

Copilot · 2026-01-28T20:54:08Z

frontend/src/components/editor/chrome/wrapper/sidebar.tsx


  return (
-    <div className="h-full pt-4 pb-1 px-1 flex flex-col items-start text-muted-foreground text-md select-none no-print text-sm z-50 dark:bg-background print:hidden hide-on-fullscreen">
+    <div className="h-full pt-4 pb-1 px-1 flex flex-col items-start text-muted-foreground text-md select-none print:hidden text-sm z-50 dark:bg-background print:hidden hide-on-fullscreen">


The class "print:hidden" is duplicated in this className string. It appears twice in the same line. Remove one occurrence to avoid redundancy.

Suggested change

<div className="h-full pt-4 pb-1 px-1 flex flex-col items-start text-muted-foreground text-md select-none print:hidden text-sm z-50 dark:bg-background print:hidden hide-on-fullscreen">

<div className="h-full pt-4 pb-1 px-1 flex flex-col items-start text-muted-foreground text-md select-none text-sm z-50 dark:bg-background print:hidden hide-on-fullscreen">

Copilot · 2026-01-28T20:54:08Z

frontend/src/components/editor/chrome/wrapper/footer.tsx


  return (
-    <footer className="h-10 py-1 gap-1 bg-background flex items-center text-muted-foreground text-md pl-2 pr-1 border-t border-border select-none no-print text-sm z-50 print:hidden hide-on-fullscreen overflow-x-auto overflow-y-hidden scrollbar-thin">
+    <footer className="h-10 py-1 gap-1 bg-background flex items-center text-muted-foreground text-md pl-2 pr-1 border-t border-border select-none print:hidden text-sm z-50 print:hidden hide-on-fullscreen overflow-x-auto overflow-y-hidden scrollbar-thin">


The class "print:hidden" is duplicated in this className string. It appears twice in the same line. Remove one occurrence to avoid redundancy.

Suggested change

<footer className="h-10 py-1 gap-1 bg-background flex items-center text-muted-foreground text-md pl-2 pr-1 border-t border-border select-none print:hidden text-sm z-50 print:hidden hide-on-fullscreen overflow-x-auto overflow-y-hidden scrollbar-thin">

<footer className="h-10 py-1 gap-1 bg-background flex items-center text-muted-foreground text-md pl-2 pr-1 border-t border-border select-none print:hidden text-sm z-50 hide-on-fullscreen overflow-x-auto overflow-y-hidden scrollbar-thin">

ditto, there is an extra print:hidden in here

Copilot · 2026-01-28T20:54:08Z

frontend/src/utils/html-to-image.ts

+        if (
+          classes.contains("mpl-toolbar") ||
+          classes.contains("print:hidden")


The filter is checking for a class named "print:hidden", but this is a Tailwind CSS utility class that gets compiled to a different class name. The actual class name in the DOM will not be "print:hidden" but something like "print:hidden" or a transformed version. This filter will not work as intended. Consider using a different approach, such as filtering based on a custom class (e.g., "no-screenshot") or checking for the computed style property (e.g., checking if the element has display:none in print media).

Copilot · 2026-01-28T20:54:09Z

frontend/src/components/data-table/pagination.tsx

          <Button
            size="xs"
-            data-testid="select-all-button"
+            data-testid="select-all-button print:hidden"


The CSS class "print:hidden" should not be part of the data-testid attribute. This appears to be incorrectly placed - the class should be in the className attribute instead. The test identifier should remain as just "select-all-button".

Copilot · 2026-01-28T20:54:09Z

frontend/src/components/data-table/pagination.tsx

          <Button
            size="xs"
-            data-testid="clear-selection-button"
+            data-testid="clear-selection-button print:hidden"


The CSS class "print:hidden" should not be part of the data-testid attribute. This appears to be incorrectly placed - the class should be in the className attribute instead. The test identifier should remain as just "clear-selection-button".

…xport to pdf

manzt

some minor nits, over all looks great

manzt · 2026-01-28T21:05:36Z

frontend/src/components/debug/indicator.tsx


  return (
-    <div className="fixed bottom-10 right-0 z-50 flex items-center justify-center bg-gray-800 py-[2px] px-1 font-mono text-[10px] text-white font-semibold">
+    <div className="fixed bottom-10 right-0 z-50 flex items-center justify-center bg-gray-800 py-[2px] px-1 font-mono text-[10px] text-white font-semibold print:hidden">


i'm guessing no-print was missed here before?

yea and in many places

manzt · 2026-01-28T21:06:24Z

frontend/src/components/editor/chrome/wrapper/footer.tsx


  return (
-    <footer className="h-10 py-1 gap-1 bg-background flex items-center text-muted-foreground text-md pl-2 pr-1 border-t border-border select-none no-print text-sm z-50 print:hidden hide-on-fullscreen overflow-x-auto overflow-y-hidden scrollbar-thin">
+    <footer className="h-10 py-1 gap-1 bg-background flex items-center text-muted-foreground text-md pl-2 pr-1 border-t border-border select-none print:hidden text-sm z-50 print:hidden hide-on-fullscreen overflow-x-auto overflow-y-hidden scrollbar-thin">


ditto, there is an extra print:hidden in here

manzt · 2026-01-28T21:07:08Z

frontend/src/components/editor/controls/Controls.tsx


 const topRightControls =
-  "absolute top-3 right-5 m-0 flex items-center gap-2 min-h-[28px] no-print pointer-events-auto z-30 print:hidden";
+  "absolute top-3 right-5 m-0 flex items-center gap-2 min-h-[28px] print:hidden pointer-events-auto z-30 print:hidden";


Suggested change

"absolute top-3 right-5 m-0 flex items-center gap-2 min-h-[28px] print:hidden pointer-events-auto z-30 print:hidden";

"absolute top-3 right-5 m-0 flex items-center gap-2 min-h-[28px] pointer-events-auto z-30 print:hidden";

manzt · 2026-01-28T21:07:24Z

frontend/src/components/editor/controls/Controls.tsx


 const bottomRightControls =
-  "absolute bottom-5 right-5 flex flex-col gap-2 items-center no-print pointer-events-auto z-30 print:hidden";
+  "absolute bottom-5 right-5 flex flex-col gap-2 items-center print:hidden pointer-events-auto z-30 print:hidden";


Suggested change

"absolute bottom-5 right-5 flex flex-col gap-2 items-center print:hidden pointer-events-auto z-30 print:hidden";

"absolute bottom-5 right-5 flex flex-col gap-2 items-center pointer-events-auto z-30 print:hidden";

manzt · 2026-01-28T21:08:21Z

frontend/src/components/ui/table.tsx

  React.HTMLAttributes<HTMLTableElement>
 >(({ className, ...props }, ref) => (
-  <div className="w-full overflow-auto scrollbar-thin flex-1">
+  <div className="w-full overflow-auto scrollbar-thin flex-1 print:overflow-hidden">


should this be print:hidden or is print:overflow-hidden correct?

this is correct (i just want to hide scrollbars when printing)

manzt · 2026-01-28T21:12:29Z

frontend/src/core/export/hooks.ts


+    // Await in-flight captures started by concurrent callers
+    for (const { cellId, promise } of inFlightWaiters) {
+      const result = await promise;


do we want an Promise.all or Promise.allSettled here?

ill add it but we never reject these. purely just to wait

github-actions · 2026-01-28T21:37:50Z

🚀 Development release published. You may be able to view the changes at https://marimo.app?v=0.19.7-dev36

mscolnick requested review from Light2Dark and manzt as code owners January 28, 2026 20:48

mscolnick requested a review from Copilot January 28, 2026 20:49

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mscolnick added the enhancement New feature or request label Jan 28, 2026

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improvement: additional print configuration, fix race conditions in e…

d300643

…xport to pdf

mscolnick force-pushed the ms/race-condition-export branch from e9ea1e2 to d300643 Compare January 28, 2026 21:03

vercel bot deployed to Preview January 28, 2026 21:04 View deployment

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mscolnick merged commit d82b3f6 into main Jan 28, 2026
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mscolnick deleted the ms/race-condition-export branch January 28, 2026 21:32

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improvement: additional print configuration, fix race conditions in export to pdf #8038

improvement: additional print configuration, fix race conditions in export to pdf #8038

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	"right-0 top-0 z-50 m-4 print:hidden flex gap-2 print:hidden",
	"right-0 top-0 z-50 m-4 print:hidden flex gap-2",

	<div className="h-full pt-4 pb-1 px-1 flex flex-col items-start text-muted-foreground text-md select-none print:hidden text-sm z-50 dark:bg-background print:hidden hide-on-fullscreen">
	<div className="h-full pt-4 pb-1 px-1 flex flex-col items-start text-muted-foreground text-md select-none text-sm z-50 dark:bg-background print:hidden hide-on-fullscreen">

	<footer className="h-10 py-1 gap-1 bg-background flex items-center text-muted-foreground text-md pl-2 pr-1 border-t border-border select-none print:hidden text-sm z-50 print:hidden hide-on-fullscreen overflow-x-auto overflow-y-hidden scrollbar-thin">
	<footer className="h-10 py-1 gap-1 bg-background flex items-center text-muted-foreground text-md pl-2 pr-1 border-t border-border select-none print:hidden text-sm z-50 hide-on-fullscreen overflow-x-auto overflow-y-hidden scrollbar-thin">

	"absolute top-3 right-5 m-0 flex items-center gap-2 min-h-[28px] print:hidden pointer-events-auto z-30 print:hidden";
	"absolute top-3 right-5 m-0 flex items-center gap-2 min-h-[28px] pointer-events-auto z-30 print:hidden";

	"absolute bottom-5 right-5 flex flex-col gap-2 items-center print:hidden pointer-events-auto z-30 print:hidden";
	"absolute bottom-5 right-5 flex flex-col gap-2 items-center pointer-events-auto z-30 print:hidden";

improvement: additional print configuration, fix race conditions in export to pdf #8038

improvement: additional print configuration, fix race conditions in export to pdf #8038

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