/copy copies an older response instead of the most recent one

Description

/copy copies a stale assistant response instead of the latest one in a multi-turn conversation.

Expected behavior

When I run /copy, it should copy the most recent assistant response in the current conversation.

Actual behavior

It copies an older assistant response instead of the latest one.

Steps to reproduce

1. Have a conversation with multiple assistant responses (at least 3–4 turns).
2. The most recent response should be a long response (e.g., an audit/review).
3. Run /copy.
4. Paste clipboard contents — observe it contains an earlier response, not the latest.

Example

• Most recent response started with: "I'm reviewing the Claude sandbox against the current ..."
• But /copy copied an older response: "## Block 4 Sandbox Package ..."

Frequency

Always (100% reproducible in my environment).

Environment

• Product: Codex CLI
• Terminal: iTerm2
• OS: macOS (latest update)
• Timestamp: 2026-04-01, Asia/Riyadh timezone

Notes

This is distinct from #16019 (where /copy fails entirely) and #15452 (SSH-specific failure). Here /copy succeeds but returns the wrong message.