[Bug] Compact progress UI missing during reactive compact operations

Bug Description
Le voici, en anglais pour que l'équipe le traite plus vite. Il est prêt à coller dans /bug :

Compact progress UI missing: plain text shown instead of the progress bar

What happens:
When compacting (manual /compact), the TUI shows only plain text with no
progress info. Expected: the progress bar that fills up (or the block/square
fallback I sometimes get, which is acceptable).

Environment:

• Claude Code 2.1.289 (native install), macOS 15 (Darwin 24.6.0), Apple Silicon
• Ghostty 1.3.1, "tui": "fullscreen"

Terminal is not the cause (from --debug log):

• Terminal capabilities: extendedKeys=yes; synchronizedOutput=yes;

kittyKeyboard=yes; kittyGraphics=yes; mousePixels=yes

• fullscreen boot canary: healthy
• Same result with TERM=xterm-ghostty and TERM=xterm-256color

Suspected cause:
Compaction goes through the reactive compact path, enabled by the remote flag
tengu_reactive_compact_remote = true. The log shows:
Reactive compact: round ladder exhausted, last resort (keeping 0 trailing messages, head truncations so far: 0)
Forked agent [reactive-compact] finished: 1 messages ...
This path seems to skip the progress bar UI.

Evidence:

• Debug session: 2940527b-3a1c-4635-8880-12f313c80dfa
• Compact request: x-client-request-id=9da78d6c-5b9c-47dc-b105-add01e545eec

(2026-10-04T23:35:12Z)

Repro:

1. Launch claude in Ghostty (fullscreen TUI)
2. Run /compact
3. Plain text is shown instead of the progress bar

Environment Info

• Platform: darwin
• Terminal: ghostty
• Version: 2.1.289
• Feedback ID: d16ecdac-b45b-4f57-9ac0-fbe02e021e7e