[FEATURE]: Collapsible tool output (code/diff/blocks) in TUI

[aravasio]

• I have verified this feature I'm about to request hasn't been suggested before.

Tool output blocks (Write, Edit, Shell, GenericTool) render fully expanded, adding noise in long sessions and making chain-of-thought hard to follow.

Request: Add a global toggle (/collapse slash command + optional keybind) that collapses all tool blocks to a summary line (file name / diff stats / line count). Per-block click-to-expand via local override on top of the global mode.

Working prototype on my fork: https://github.com/aravasio/opencode/tree/collapse-tool-output

Happy to open a PR if this direction is accepted.

Screenshots for reference

[github-actions]

Thanks for updating the issue! It now follows the contributing guidelines and the needs:compliance label has been removed. We appreciate you including a working prototype — that's very helpful context.

[aravasio]

Related existing issues:

• [FEATURE]: Add keyboard shortcut to toggle tool output Click to expand #14511 — Keyboard shortcut to toggle tool output Click to expand. Requests a keybind to expand/collapse the last tool call.
• [FEATURE]: Add Native Fold/Collapse and Unfold/Expand Tools for Conversation and Tool Output Spans #15935 — Native Fold/Collapse and Unfold/Expand Tools
• [FEATURE]: per-tool output visibility #17250 — Per-tool output visibility
• FEAT: Expandable view for MCP tool params and results (TUI) #9781 — Expandable view for MCP tool params and results

The approach in this issue (global /collapse toggle + per-block click) is broader than #14511 — it adds a persistent toggle mode (not just last-output), a slash command, and a KV-backed global state. But the core UX overlap is real.

Happy to consolidate if maintainers prefer one approach over the other.