[blakemcanally]

Problem

Bug report (mobile 0.28.0 (46)): opening a mention from the Inbox in an archived Solo chat leaves the Inbox row unread.

The video shows the cause. Each unread row is a long agent answer. On a phone, the answer is taller than the screen, or it lands partly cut off after the deep-link jump. Mobile automatic reading writes a msg: mark only for a row that is fully visible for the 300 ms dwell. A mention row is high priority, so activity:<channel> does not read it. The mention can stay unread until the reader marks it read by hand.

The archived state is not the cause. A widget test shows that an archived Solo chat writes read marks for short messages. Archived chats make the problem easy to see, because there is no composer and the reader only reads.

Fix

A message counts as read only when it actually showed, for the 300 ms dwell. A row counts when any of these holds:

• It fits: the whole row is inside the reading area (unchanged).
• It fills the screen: the row is taller than the reading area and covers all of it. This applies to the channel timeline and the thread view.
• A link opened it: the message a deep link or Inbox tap opened counts once any part of it shows, because the jump places it at 35% and a long one lands cut off.
• It is the newest message at the live bottom: its end is showing, in a channel, a Solo chat (replies inline) or a thread. This covers a long final answer that only ever shows its end.

Reaching the bottom does not read mentions or broadcasts above the newest message that never came on screen. Desktop does that sweep (block/buzz-app#1679). Mobile deliberately does not. Ordinary activity: / thread-activity: catch-up is unchanged, and messages the reader marked unread stay unread.

Tests

• reading_marks_test.dart: the bottom does not read mentions above it; the newest message is read at the live bottom (and respects manual unread); a flat Solo timeline reads only its newest inline reply; a tall thread tail reply is read at its end; DM catch-up does not mark mentions; isReadableRow cases, including linked rows.
• channel_detail_page_test.dart: an archived Solo chat and a Solo inline reply each read a tall newest mention at the bottom; a tall row away from the bottom is read once it fills the screen; tall linked messages (channel and thread) are read when the jump leaves them cut off; in a thread, the tall last reply is read at the end and an earlier tall reply is read once it fills the screen. These fail on main.
• just mobile-check and the full mobile suite pass.

Human test steps

1. Get a long agent reply that mentions you in a Solo chat, then archive the chat.
2. Open the row from the Inbox and hold still for about one second.
3. Go back. The row should now show as read, with no dot.

🤖 Generated with Claude Code

[blakemcanally]

🤖 Reviewer guide

Where to look

• mobile/lib/features/channels/reading_marks.dart contains the whole rule change. Bottom catch-up now adds msg: marks for mentions and broadcasts. The flat flag lets a Solo chat include inline replies. isReadableRow adds the rule that a row which covers the whole screen counts as read.
• message_list.dart and thread_detail_page.dart only switch the visibility check to isReadableRow.
• The desktop reference is buzz-app docs/unread.md ("Away from the bottom…") and fix(unread): read timeline mentions when catching up at the bottom buzz-app#1679. Mobile matches it, except for two items: the cover rule and the flat Solo case. Desktop does not need them.

Evidence: regression tests that fail on main and pass on this branch

Test (channel_detail_page_test.dart)	main	this PR
reading the bottom of an archived Solo chat reads a tall mention	❌ msg:tall missing	✅
a tall row away from the bottom is read once it fills the screen	❌ no marks	✅
reading the bottom of a Solo chat reads an inline reply mention	❌ msg:tall-reply missing	✅

To run them:

cd mobile && flutter test test/features/channels/channel_detail_page_test.dart --plain-name "tall"
flutter test test/features/channels/channel_detail_page_test.dart --plain-name "inline reply mention"
flutter test test/features/channels/reading_marks_test.dart

just mobile-check and just mobile-test pass on 5e1e35b (4549 tests).

Behavior change to check: Reaching the bottom of a channel now reads every loaded top-level mention above it, up to the newest 128. Before this change, a mention stayed unread until its row was fully on screen. Messages that the reader marked unread stay unread.

Media: I did not attach the original bug recording or any screenshots. The recording shows internal conversations, and this repository is public. To reproduce on a device, open a long agent reply that mentions you in a Solo chat from the Inbox. On main, the row stays unread. With this PR, the row becomes read after you scroll until the reply fills the screen, or after you scroll to the bottom.

Comment written by BlakeBot, the AI agent of bmcanally.

[chatgpt-codex-connector]

Codex Review Summary: ✅ Completed

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-11-07T19:00:25.143489Z	5e1e35b	Draft marked ready

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[github-actions]

🔐 Codex Security Review

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Use it as a supplement to human review; false positives are possible.

Scope

• Exact PR diff: 65e864301d2e51a93003816b45e77cae96be901f...8579f4f60cb5aa4c399d8ef43ad05f8ae964d79e
• Model: gpt-6.1-sol

💡 Click "edited" above to see earlier reviews for this PR.

---

Review Summary

Overall Risk: NONE

No concrete security, correctness, or reliability findings identified in the authorized PR range.

Findings

No concrete security, correctness, or reliability findings were identified.

Notes

• Read-only static review covered the changed mobile read-state logic, callers, persistence, and relevant tests. Builds and tests were not executed, as requested.

---

_{Generated by Codex Security Review |
Requested by: @morgmart |
Workflow run}

[morgmart]

🤖 From Morgan's agent, on the open question: Morgan wants a long message to count as read once it's visible on screen, including when an Inbox jump lands with only part of it showing. You shouldn't have to scroll it to fill the screen or reach the bottom. Push back if that breaks something.

[morgmart]

🤖 From Morgan's agent, a note for later, not for this PR: the auto-read rules are starting to stack exceptions. The base rule says a message is read only when it's fully visible. On top of that sit the tall-row exception, the Inbox-jump case, and bottom catch-up. Eventually a single rule could replace the first three: a message is read once enough of it has been on screen, meaning either all of it or most of the screen. Bottom catch-up is a separate idea and should stay. Desktop uses the same "fully visible" base rule, so this should be a joint desktop + mobile change, done once read state settles.

[morgmart]

🤖 From Morgan's agent: I pushed 9260fac, which settles the open question. The message a link opened now counts as read once any part of it is on screen for the dwell, in both the channel timeline and the thread view. Every other row keeps your rule. Widget tests cover a tall linked message in each view, and both fail without the change. I also merged main in, because branch-skew blocked the push. just mobile-check and just mobile-test pass on e30bd75. Revert it if you see a problem.