feat: 503 and 504 outage pages

[joshlarson]

Scope

Note

I'm not entirely sure that this is the right way to version this, since these pages won't actually be served from a running Dotcom instance. I figure this is as good a place as any to stash them and iterate on them though 🤷

Asana Ticket: 📈 🛠️ [#3378] Implement custom error pages for MBTA.com when app is down

Implementation

Note

🤖 I used Copilot to build the first draft of this, and then iterated on it both with further AI prompts and by hand. Each commit whose prefix includes (robot) was generated by AI - the others were hand-written by yours truly.

Screenshots

How to test

Open the files. The buses blink!

[jlucytan]

If this is just meant to be an archive of the current state of the pages, perhaps we can keep this as a draft branch to be used for reference for perpetuity? Although the visibility isn't the greatest, so I'm not opposed to merging it in either, but I think it's a bit confusing to have the pages there while they're not being served, and future devs will just have to know that updating them does nothing.

[joshlarson]

[...] I think it's a bit confusing to have the pages there while they're not being served, and future devs will just have to know that updating them does nothing.

Yeah that's a good point. I wonder if we should put them in a clearer place, alongside a README that explains what they're for and how they actually get "deployed" (which .. uh... currently I don't even know)

[jlucytan]

lgtm, if you find a good place to move them and/or can add a comment somewhere in the repo (maybe the README would be good enough?) about their non-served status, I think that would be useful

[thecristen]

Lighthouse is flagging the SVGs for not having an an accessible text alternative. I think the big bus picture is decorative and should use aria-hidden="true", and probably doesn't need role="img". And maybe the same for the app store ones, but the links might need better labels ("Download on the App Store" doesn't say which app store 😅)

[joshlarson]

@thecristen and @jlucytan I just re-requested review from both of you - I think I've addressed your comments (and made the VO experience for the 503 and 504 pages a lot nicer).

I'm also hoping to add a 502 page, since we see that error too sometimes, but I'm planning on having that page be 100% identical to the others, but with a 502 blinky bus and the appropriate text changed.