Tool output panel: scrollback + full-content expand toggle

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

During long debugging sessions, the right-side tool-call panel accumulates many entries (Read, Bash, Edit, "Background command completed", etc.). Two related problems emerge:

1. As entries pile up, the panel compresses them into a single visible page. Older entries shrink until the text becomes unreadable (resolution-limited collapse). There's no effective way to scroll back through the tool history.

1. The small expand arrow next to each tool result reveals only the first ~4 lines of output. There is no way to view the full output inline without leaving the conversation.

The only current workarounds are /clear (loses conversation context) and /compact (loses fidelity). Neither preserves the ability to review what actually ran during the session.

Proposed Solution

Improve the tool-output panel viewability with two interactions:

• Independent scrollable tool panel: keep the last N tool entries in memory, scrollable freely (e.g. PageUp/PageDown when focused, or mouse wheel). Older entries remain at their natural readable size — they go off-screen instead of being compressed.

• Full-content expand toggle: clicking the expand arrow next to a tool result reveals the full output (analogous to Ctrl+O in claude.ai). A second click collapses back to the compact view.

Together these let users review what happened earlier in the session without losing conversation context or readability.

Alternative Solutions

• Use /clear to drop visible history (loses all conversation context — unusable for long debugging sessions).
• Use /compact to summarize (loses tool-output fidelity).
• Resize terminal to make text larger (reduces visible items, doesn't solve compression).
• Manually grep through hook logs outside Claude Code (breaks the inline workflow).

Priority

Medium - Would be very helpful

Feature Category

Interactive mode (TUI)

Use Case Example

Scenario: long debugging session for an OCR pipeline (50+ minute session, dozens of Bash/Read/Edit calls).

1. I run a pipeline batch with 30+ Bash commands, each producing log output.
2. Halfway through I need to recheck what a Read call returned earlier in the session.
3. With current UI: the panel has compressed all entries into illegible text; the expand arrow shows only 4 lines so I can't see the full Read output.
4. With this feature: I scroll back to the relevant Read call in the tool panel, click the expand arrow, see the full file content, click again to collapse.
5. Saves manually re-running the Read tool just to see the output again.

Additional Context

Reference behavior: Ctrl+O in claude.ai expands a code block / tool output to full content; clicking again collapses. The same interaction pattern would feel native in the TUI.