The gateway already ships per-tool arg metadata the client was discarding:
`context` (build_tool_preview's primary-arg line, always sent), `args` (full
dict on complete), `args_text` (redacted JSON, verbose), `duration_s`. Capture
them on the tool part and render free-code style:
- collapsed header: `▶ name <arg-preview> · <duration> (N lines)` — args are
finally visible without expanding (the core item-2 complaint).
- expanded: a single left-bordered (`│`) column with a key:value args block
(suppressed when the lone arg is already the header preview — judge nit) then
the output block.
- strip the gateway's `[showing verbose tail; omitted N chars]` banner into a
tidy `… omitted N chars` note; unwrap tail-capped `{"output":…}` envelope
fragments so the last line isn't a dangling JSON tail.
Left bar is a border glyph (opencode BlockTool style), not a bg fill — cleaner
and renders faithfully. +4 unit tests, +1 render test (78 pass).
alt-glitch
aec752faa3