How does this work on Android? I've definitely seen notifications with cut-off text messages too. Generally we try to match them.

1. We should see if the message center supports explicit dismissal, i.e. clicking the message text shouldn't remove it from the message center.
2. The message center is the *only* UI we have for SMS on Chrome OS - We do not have a full feature SMS app like Android does.

We need to confirm:
a) Does clicking on the message actually remove it, or just hide it into the message center (which seems fine).
b) Is the message text truncated only in the initial popup, or alsw when viewed when opening the message center?

Also, what is the maximum length of a single SMS message?

Re #2:

(a) Confirmed that clicking the message hides it into the message center. It can still be found by opening the message center, which is good.

(2) A SMS message is typically up to 160 characters. A longer message may be broken up into 160-character chucks. The notification (in expanded view) can fit a 160-character message if the message fits into 4 lines. If the message doesn't fit into 4 lines (e.g. it contains some line breaks), the notification (in expanded view) shows only the first 3 lines and "..." at the end (see attached screenshot).

So it turns out the message length isn't the main issue here, the number of lines occupied by the message is.

OK. Thanks! It should be straightforward to allow the message center to support an "SMS" view that:
a) Shows a larger (but reasonable) number of lines, e.g. 10.
b) Eliminates blank lines.

ketakid@ - Can you cc: the correct UX person for their input?

This issue has slowed down for a while. 

per#5, this seems to me that we're waiting for the correct UX person?

UX input would be great, but I'm not blocked on that, just higher priority issues.

Ben, is there a way to repro this on linux? Or on a coral device with the sim card I have?

Do we need this for 64, or is 65 sufficient?

Re #8:

stevenjb:  One simple way is use the fake class to inject a SMS message with a few line breaks, which will increase the vertical space needed for showing the SMS message in the notification window.

If we're ok with the approach that you suggested in #5, I can create a CL as well

He Ben, can you elaborate? I haven't used the Fake SMS class in ages and --sms-test-messages doesn't seem to 'just work'.

Adding Alex to comment on this issue. Alex, what do you think about the behavior below?

 It should be straightforward to allow the message center to support an "SMS" view that:
a) Shows a larger (but reasonable) number of lines, e.g. 10.
b) Eliminates blank lines.

benchan@ - I'm going to take you up on your offer and assign this to you since I can't remember how to test this on linux chromeos and need to focus on other things. Ping me if you run into any issues.

The notification view has a hardcoded limit of 4 lines, which we should revisit in a UI review.

As an interim workaround, I'm going to collapse whitespaces (e.g. extra line breaks) in SMS messages, which helps minimize the number of lines occupied by the SMS message in the notification view.

Ben, if you could paste instructions for testing SMS messages in the CL I
would be happy to investigate the 4 line limit.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/28e5fe5cc026ffb6a6479b0b94be52737455737d

commit 28e5fe5cc026ffb6a6479b0b94be52737455737d
Author: Ben Chan <benchan@chromium.org>
Date: Tue Dec 12 21:07:53 2017

Collapse whitespaces when showing an SMS message in notification.

The notification view for SMS messages is limited to show at most 3
lines, which is not sufficient to show the full content of a SMS message
with multiple line breaks. As a workaround, this CL collapses
whitespaces in a SMS message to minimize the number of lines needed to
show the SMS message in the notification view.

Bug:  775786 
Change-Id: I807a50c888a1d36439b19805e946d7fb261de633
Reviewed-on: https://chromium-review.googlesource.com/821850
Commit-Queue: Ben Chan <benchan@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#523546}
[modify] https://crrev.com/28e5fe5cc026ffb6a6479b0b94be52737455737d/ash/system/network/sms_observer.cc

I think sgabriel@ is the right designer to look at this.

As an aside, how does one respond to SMS messages in Chrome OS? I would expect that clicking on the notification brings me to some messaging app that allows me to send messages, is that not the case?

One does not. SMS support is only so that a carrier can send account messages to the user. At least so far.