feat(codex): read Codex's own background-terminal row

Codex states background work too, and it says so in a different place. Claude
writes `· 1 monitor ·` on the last row of the screen; Codex pins
`1 background terminal running · /ps to view · /stop to close` ABOVE its
composer, which puts that row third from the bottom once the status line and
the composer are counted.

So how far up the screen to look is now per-CLI data as well:
`capabilities.workDetect.watchingLines`, bounded to 1..8 by the schema, and
defaulting to Claude's two. That bound is the point. The window is half the
injection guard, since every row it adds is another row the agent itself may be
able to write, and the label is what silences an idle alert. The other half is
the anchor, and Codex's is ` · /ps to view`: chrome naming a slash command only
the CLI can offer, so a session that writes "I left 1 background terminal
running for you" into its own output matches nothing.

Measured against a live codex-cli 0.154.0 pane rather than read out of a
binary. The row appears when the terminal starts, follows the composer down as
the conversation grows, and is gone after `/stop`. Verified end to end on an
isolated beta: the session payload carried `watching: "1 background terminal"`
and the badge rendered with it, and both cleared when the terminal stopped. The
fixtures in the tests are that capture verbatim.

Codex has no hook signals, so no idle prompt and no false NEEDS YOU row: for a
Codex session this is the badge alone, which is the case the maintainer said a
registry field could cover and a hook never could. Cross-CLI tests pin that
neither pattern fires on the other's screen, and that a CLI declaring nothing
still reports nothing.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.changeset/watching-badge.md

@@ -4,7 +4,7 @@
 
 A session watching work it started itself no longer asks you to look at it. An agent that arms a monitor, backgrounds a shell or hands a task to a cloud session is told to end its turn, so the pane goes quiet, Claude Code's idle notification lands a minute later, and the session shows up under NEEDS YOU with nothing for anyone to answer.
 
-Claude prints what it is still running on the last row of its screen, and the CLI registry now carries that row as an optional `capabilities.workDetect.watchingLine`. The idle probe reads the label ("1 monitor", "2 shells") off the capture it already takes when a turn ends, and it reaches the session payload as `watching`.
+A CLI states what it is still running on its own screen, and the CLI registry now carries that row as an optional `capabilities.workDetect.watchingLine`. The idle probe reads the label off the capture it already takes when a turn ends, and it reaches the session payload as `watching`. Claude writes its chip on the last row (`· 1 monitor ·`, also shells, cloud sessions and background tasks); Codex pins `1 background terminal running · /ps to view` above its composer and declares the deeper window that needs. Both patterns were measured against live panes, and a CLI that declares none reports no background work, as every CLI did before.
 
 The prompt that follows then opens already acknowledged. It stays in the Approvals drawer, stays answerable and stays Read My Mind context, and only the alert it would have armed is spent: no tab alert, no desktop notification, no push, and no NEEDS YOU row on any surface, `codeman tui` included. The card says why, reading "quiet, watching 1 monitor" rather than implying somebody looked. It re-arms by itself, because the next idle prompt supersedes this item and is built fresh. A permission or question dialog still goes red whatever else the agent started.