Tool-call cards and grouping, with the state a result never arrived in

P1b (docs/RUST.md). `transcript-ui/src/tool.rs` draws a card per tool
call and a group per run: collapsed, a card is its name and the one-line
summary `parse_tool_input` derives; open, it is the description, the
input (highlighted, on the verbatim surface) and the output, capped with
a "Show all N lines". A run is one surface with a heading and a chevron
bar at its foot, so it closes from either end.

Three things worth knowing.

**A collapsed card lays out its summary line and nothing else.** The
fixture's tool outputs are tens of kilobytes and a collapsed card never
builds a widget for one -- `collapsed_cards_shape_only_their_summary_
lines` opens a three-card group over 88 kB of output each and asserts the
text-shape count equals the same group's over three bytes (17 either
way; 17 against 20 when the discipline is deliberately broken, so the
test is real).

**A result arriving replaces one card.** `ToolRow::apply_calls` is the
group's half of `RowBlocks::apply_delta`'s rule, and `build_row` now
hands back one `TailRow` -- blocks for a message, cards for a run --
rather than two mechanisms chosen at each call site.

**Every tap is a tap**: `GestureOutcome::Tapped` out of the `DragArbiter`
`Selection` already owns, so a drag that started on a card scrolls the
transcript instead of opening it.

Three defects found by looking at the render, all recorded with their
repro in docs/IRIS_TODO.md: a `Span` of padded children inside another
`Span` places them a slot out of step (worked around by building the
group as one span, which costs the 4dp inset); `scrollable_on(Axis::X)`
on a non-editable text draws nothing, so a card's command is clipped
rather than pannable; and `NotoSans-Regular` has no U+25B8/25BE/25B4 at
all, so the expander mark is set in the monospace face.

Screenshots: docs/bench/p1b-2026-09-06/.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

docs/DECISIONS.md

@@ -5,6 +5,45 @@ they can be judged and reversed later. Detail lives in RUST.md (and IRIS.md
 for iris API changes); this file is only the summary. Newest first. Items
 marked **DEFERRED** are ones the agent chose not to decide alone.
 
+## 2026-09-06 (how a tool call looks, P1b)
+
+- **A card that never got a result says "no result", in yellow, and it is
+  a state Compose cannot say.** A call that finished having printed
+  nothing and a call whose turn was interrupted before anything came back
+  both leave an empty output. Compose draws both as an ordinary finished
+  call, which reads as a fact somebody established. There are five states
+  now, each with a word and a colour: nothing at all for a call that
+  worked, "running" (grey), "your turn" (peach, Compose's own wording and
+  colour), "failed" (red), "no result" (yellow).
+
+- **A failed call is drawn as failed, which needed a field on the wire.**
+  `is_error` is on the CLI's `tool_result` and was being dropped; the
+  server now carries it to the phone. Reversible, but the alternative is a
+  card that says a call succeeded because it cannot tell.
+
+- **A group's cards do not each carry their own surface.** Compose gives
+  each card a fill and squares the corners where it faces a neighbour, so
+  a run reads as one object broken into parts. iris has no per-corner
+  radius, and -- more to the point -- a group built the way Compose builds
+  it hit a framework layout defect that drew every card's text a card
+  below its own box. So a group is one surface with its cards on it,
+  separated by a small gap, and the 4dp inset Compose holds them off the
+  edge by is gone. Worth revisiting once the layout defect is fixed
+  (docs/IRIS_TODO.md).
+
+- **A long tool output is capped at 80 lines or 4 kB with a "Show all N
+  lines".** Compose draws the whole thing, and gets away with it because
+  its `Text` inside a `LazyColumn` lays out lazily; here the output is one
+  text widget and shaping a hundred kilobytes of it costs what the file
+  editor's 32 kB limit was measured against. If iris's text gets cheaper,
+  this is the number to move.
+
+- **A card's command is clipped, not pannable, and its summary line is
+  clipped rather than ellipsised.** Both are framework gaps rather than
+  choices (`scrollable_on` on a non-editable text draws nothing; there is
+  no overflow ellipsis), and both are worse than Compose today. Named here
+  because they are visible.
+
 ## 2026-09-06 (how a markdown block looks, P1a)
 
 - **A table is drawn as padded monospace columns, not as a grid.** Your