The last wire of the feature, and what makes the four slices above one thing:
the cover drawer now renders the conversation transcript, so opening agent
activity in a channel lands in the reading view rather than the dense activity
feed. Resolves the `TODO(#6538)` slice A landed with.
The variant is chosen by presentation, not inferred from panel width. Width was
only ever a proxy, and a breakable one — the split pane can be dragged wide and
a narrow overlay can be tall. The presentation that already decided to cover is
the thing that knows this is a reading surface, so it decides the variant too.
Non-cover hosts return `undefined` rather than `"default"`: the panel already
defaults, and naming it here would imply this function decides the non-cover
variant when the profile panel picks `compactPreview` at its own call site.
Asserted end-to-end on the transcript's `data-transcript-variant` marker rather
than on the prop, so the test proves the value survives the whole path from the
resolver through `ChannelAgentSessionSurface` and the panel to the transcript.
It lives in the screenshot spec because the marker only renders once the
transcript has content, and that is the spec that seeds a turn. Verified
discriminating: reverting the pinned value alone fails the assertion.
Co-authored-by: Bradley Axen <baxen@squareup.com>
Signed-off-by: Bradley Axen <baxen@squareup.com>
Signed-off-by: ss-dev-00 <a02c4e0850e5e612b4ddf95dbe2f5c56467cf27c6552203bc833ff438fb31971@buzz.block.builderlab.xyz>
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