fix(pad): URL view-option params lost to padeditor.init race (#7840)

[JohnMcLear]

Summary

Closes #7840. ?showLineNumbers=false (and ?useMonospaceFont=true) on an iframe-embedded pad get re-applied to the server default a few hundred ms after pad boot. Same race that affected ?rtl=false before #7464 — generalises that fix to the neighbouring URL view-toggles.

Why the iframe reporter sees it and direct users don't

The race always fires, but it only becomes observable when the value padeditor.init's deferred setViewOptions(initialViewOptions) call re-applies disagrees with the URL param. initialViewOptions is built from cookie pref ?? server default:

• Direct-browser users typically have a prefs cookie from a prior in-pad toggle that matches what they're asking for via URL → no observable race.
• Cross-context iframe embeds with no cookie → server default showLineNumbers:true fights the URL false → URL preference visibly lost.

What the race looks like

1. _afterHandshake → getParams() sets settings.LineNumbersDisabled = true.
2. _afterHandshake calls padeditor.init(view).then(postAceInit) — async; ace iframes still loading.
3. Sync tail of _afterHandshake hits the URL-param block: changeViewOption('showLineNumbers', false) → queues setProperty('showslinenumbers', false) in Ace2Editor.actionsPendingInit (loaded=false).
4. ace.init resolves → loaded=true → queue flushes → URL-driven false applied.
5. padeditor.init resumes past its own await and runs self.setViewOptions(initialViewOptions) — initialViewOptions.showLineNumbers === true (server default) → setProperty('showslinenumbers', true) runs against loaded=true and immediately re-shows the gutter.

#7464 spotted this for RTL and moved the override into postAceInit. The neighbouring blocks for showLineNumbers / noColors / useMonospaceFontGlobal at the same synchronous-tail site never got the same treatment. This PR generalises that fix.

Test plan

• New spec `src/tests/frontend-new/specs/url_view_options.spec.ts`:
  • `?showLineNumbers=false` → outer body has `.line-numbers-hidden` on first paint
  • `?showLineNumbers=true` no-regression
  • `?useMonospaceFont=true` → `#viewfontmenu` value is `RobotoMono` on first paint
• Verified the three race cases fail on `develop` before the fix.
• Verified `rtl_url_param.spec.ts`, `timeslider_line_numbers.spec.ts`, `pad_settings.spec.ts`, `embed_value.spec.ts`, `hide_menu_right.spec.ts` still pass (26/26 green together).

Not in scope

• The `?noColors=true` URL path turns out to be unaffected for the inner-body `authorColors` class (the override at `pad_editor.ts:268-270` always wins). The colorscheck checkbox UI doesn't reflect `settings.noColors` in either the racy or fixed state — that's a pre-existing cosmetic mismatch independent of this race and worth its own follow-up.

🤖 Generated with Claude Code

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Review Summary by Qodo

Fix URL view-option params lost to padeditor.init race

🐞 Bug fix 🧪 Tests

Walkthroughs

Description

• Move URL view-option overrides into postAceInit to prevent race condition
  - Fixes showLineNumbers, noColors, useMonospaceFont params being clobbered
• Generalizes fix from #7464 (RTL race) to all three neighboring view toggles
• Add comprehensive test suite for URL view-option parameters on initial load

Diagram

flowchart LR
  A["_afterHandshake sync tail<br/>queues URL overrides"] -->|"race condition"| B["padeditor.init resolves<br/>calls setViewOptions"]
  B -->|"clobbers URL values"| C["Server defaults applied<br/>URL params lost"]
  D["postAceInit<br/>after padeditor.init"] -->|"fix: moved here"| E["URL overrides applied<br/>after initialViewOptions"]
  E -->|"no race"| F["URL params preserved"]

Loading

File Changes

1. src/static/js/pad.ts 🐞 Bug fix +17/-18

Move URL view-option overrides to postAceInit

• Moved LineNumbersDisabled, noColors, and useMonospaceFontGlobal URL-param overrides from
 _afterHandshake sync tail into postAceInit function
• Added detailed comment explaining the race condition and why these overrides must run after
 padeditor.init resolves
• Removed duplicate override logic from the synchronous tail section (lines 807-829)

src/static/js/pad.ts

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2. src/tests/frontend-new/specs/url_view_options.spec.ts 🧪 Tests +49/-0

Add URL view-option parameter race condition tests

• New test file covering URL-param view options on initial pad load
• Tests ?showLineNumbers=false hides line-number gutter on first paint
• Tests ?showLineNumbers=true keeps gutter visible (no regression)
• Tests ?useMonospaceFont=true applies monospace font on first paint
• Clears cookies in beforeEach to simulate cross-context iframe embeds without prior preferences

src/tests/frontend-new/specs/url_view_options.spec.ts

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Code Review by Qodo

🐞 Bugs (0) 📘 Rule violations (0) 📎 Requirement gaps (0)

Great, no issues found!

Qodo reviewed your code and found no material issues that require review

[SamTV12345]

Makes sense that it is now firing correctly.