Fix the reading, navigation, and sending bugs by giving each its own tested module - #1

Summary

Fixes a set of bugs in reading, chat navigation, lists, and sending. Most of them show up as tria acting on something other than what is on screen: a pull request asked for that never opens, a key that lands on lines the screen no longer shows, gs settling a different thread than the one marked, a refused message written over what was typed since.

They share one cause, so they are fixed together. Each of those behaviours was spread across App's fields and read state that only drawing kept current. So the rules sat in the gaps between functions, and tests could reach them only by driving a whole App and drawing a frame. Each area now has one module of its own. That module is lent what it needs on each call, makes no calls of its own, and hands back what should happen for App to carry out. That makes each module testable without tokio, a channel, or a drawn frame. That is how each bug below was first pinned by a failing test.

The new modules, and what each owns:

src/
├── reader.rs          # a reading: a subagent's transcript or a pull request, read in place of the chat
├── chat_view.rs       # the chat's cursor, scroll, selection, count, and search
│   └── layout.rs      # the chat laid out when asked about, cached by what it shows and its size
├── sidebar_view.rs    # the sidebar's selection by item, offset, tabs, and kept places
├── list_cursor.rs     # the terminals, worktrees, and subagents popups' selection by item
└── outbox.rs          # a message's life: send, queue, start a thread, link, rewind, :implement, drafts

Reader and Outbox return typed requests, which App carries out through session::Handle, and the answers come back in. commands.rs stays the only place wire JSON is built.

key or server event
  App decodes it and lends the module what it needs
    module.method(...) -> Step { requests, give-backs, toast, where to go }
  App carries out the Step through session::Handle
  the answer comes back as one AppEvent, forwarded to the module

CONTEXT.md is new. It names the terms these modules use: a reading, a transcript, loud and quiet reads (asked for, or only bringing what is open up to date), following a subagent still working, and a pull request stack.

Behaviour changes on purpose, beyond the fixes:

• A refused message goes back into its composer only if that composer is empty. Otherwise it goes into the composer's history, and the toast says so. This covers refused sends, refused or interrupted queued messages, and refused new threads. A refused new thread used to write over the composer.
• Long terminal and subagent popups scroll to keep the selection in view, as the worktree list already did. Lists that fit are drawn exactly as before.
• Rewinds are per thread. Rewinding one no longer blocks gr on others. A rewind on a thread that isn't open resolves when it is reopened or at the deadline, with its text put into that thread's parked draft.
• The chat is no longer laid out again on every spinner tick while a thread works (about 8 times a second). A pull request's "N m ago" times refresh once a minute instead.
• The panel for answering an agent's question wraps a long option onto more rows, lined up under the option's text, instead of cutting it off. The option under the keys is tinted like the chat's cursor line, so its grey description can be read. It used to be grey text on a grey background.

Review on this PR also found older problems, fixed here in their own commits:

• gh's token is sent for a pull request's pictures only over HTTPS. Before, an http:// picture on the pull request's host got it too.
• Search no longer crashes on a line whose lowercase is longer than it, such as one with İ, and the match it highlights is the one it found.
• A pull request asked for while a read of it is on its way is read again once that answer arrives, so a label just set is not undone by the older answer.
• A new thread is named for its first line with anything in it, instead of an empty or cut-short title.

Evidence

Each fix below was written as a test first, and seen failing on the code before it.

• Before: asking for pull request B while a sync quietly refreshed open pull request A dropped B. The "reading #B…" toast expired and nothing opened.
  After: B opens.
  reader::a_quiet_read_does_not_cancel_a_loud_one: open B, refresh A, B answers → B is opened at the top (was: nothing).
• Before: Enter on a transcript being followed was ignored, and following moved the highlighted row in the subagent list.
  After: Enter opens it, and following leaves the selection alone.
  reader::asking_for_a_transcript_being_followed_opens_it_loudly, app::following_leaves_the_rosters_selection_alone (selection was moving from 0 to 1).
• Before: a motion in the same event batch as a fold or new output ran against the old layout.
  After: it lands on the new one.
  app::a_motion_after_a_fold_in_the_same_batch_lands_on_the_new_layout (landed on line 4, now 7).
• Before: after the sidebar's threads reordered, gs settled the wrong thread. After a section collapsed, Enter did nothing.
  After: both act on the row marked.
  app::gs_settles_the_thread_marked_after_the_list_moves (settled b, now a), app::enter_acts_on_the_row_marked_after_the_list_shrinks.
• Before: in the terminals popup, x closed whatever terminal slid under the highlight after a re-sort.
  After: it closes the marked one.
  app::x_closes_the_terminal_marked_after_the_list_resorts (closed c, now b), plus the same for shrinking and for the subagents popup.
• Before: two new threads created close together overwrote each other's pending state, so a refusal lost its text.
  After: each keeps its own.
  outbox tests for two creates in flight, answered in either order.
• Before: a queued message could stay stuck forever after a reconnect.
  After: it is released once the thread is idle.
  Before: a message given back could keep its "Sent looking at…" prefix.
  After: the plain text comes back.
  Before: a message could appear twice in the composer's history.
  After: it appears once.
  Before: a rewind blocked every other thread, and :implement ran during one.
  After: both are fixed.
  Before: :implement new pulled you to the new thread after you had moved on.
  After: it stays put.
  Each has a failing-first outbox or app test.
• Before: a long option in a question's answer panel was cut off with …, and the option under the keys was drawn in the grey of its own background.
  After: it wraps under itself and can be read.
  ui::a_long_option_wraps_under_itself (found the …), ui::the_option_marked_can_be_read (found a ( drawn in its own background colour).
• Before: searching a chat line with İ in it panicked with "index out of bounds", and a line with a word-final ΟΣ matched ς without the match being highlighted.
  After: both are highlighted where they match.
  chat_view::search_matching_is_smartcase, with İa and ΟΣ İ cases added.
• Before: an http:// picture on a pull request's host was fetched with gh's token, and a label set while a read was on its way could be undone by that read.
  After: the token goes only over HTTPS, and the pull request is read once more.
  reader::pictures_are_fetched_once_and_again_after_failing, reader::a_label_set_while_a_read_is_on_its_way_is_read_for_again.

Every commit passes cargo fmt --check, cargo clippy --all-targets --locked -- -D warnings, and cargo test --locked. The test count went from 320 to 429. Before each commit, a separate review compared the diff with the code it replaced. Its findings were fixed before committing:

• the sidebar reveal staying pending and scrolling to follow the item;
• two threads sharing a worktree path trapping j;
• the popups losing a row at some screen heights;
• a rewind wrongly marked as landed from the thread list.

Merge Danger

Door: two-way

Each of the thirteen commits stands alone and can be reverted on its own. Nothing is stored or migrated. The outbox, drafts, and view state live only in memory, as before.

Blast Radius: interaction

Anyone using tria would notice a regression as a key, click, or message doing the wrong thing, rather than a crash. The riskiest areas are the chat and the sidebar:

• Chat content that changes without its revision moving would now be drawn stale. The spinner's constant relayout used to hide that. A review found no such path, and pictures dropped from the image cache are placed again on draw.
• Given-back message text is now handled by one rule instead of three.

Summary by CodeRabbit

• New Features

  • Browse subagent transcripts and linked pull requests alongside conversations, refresh readings, and move through stacked pull requests.
  • Navigate chat with cursor movement, message and word jumps, scrolling, selection, and case-aware search.
  • Use separate Threads, Pull Requests, and Agents sidebar tabs while retaining each tab’s position.
  • View images within chat and copy selected text.

• Bug Fixes

  • Unsent, interrupted, or rewound messages are returned to the appropriate composer, draft, or history rather than being lost.
  • Chat and sidebar selections remain anchored more reliably as content changes.