Impact

When working with multiple Hermes TUI sessions side by side — a common workflow for managing parallel development tasks — users resize terminal windows frequently. Each resize event causes blank separator lines (─) to accumulate in the prompt area. After a few resize operations, the TUI becomes cluttered with dozens of ghost lines, forcing the user to run /clear repeatedly.

This is not a cosmetic issue. It interrupts the development flow for users who rely on multi-window Hermes setups to manage concurrent agent tasks.

Steps to Reproduce

1. Run hermes --tui in multiple terminal windows
2. Start a conversation in each
3. Resize any of the terminal windows (drag edge, maximize/restore, or switch between full-screen splits)
4. Observe: each resize adds one or more blank lines filled with ─ below the input prompt <img width="1054" height="790" alt="Image" src="https://github.com/user-attachments/assets/5b443035-af13-41f2-9c03-b1ff2d87c0dd" />

<img width="1054" height="790" alt="Image" src="https://github.com/user-attachments/assets/86959c96-c5cb-4629-8b55-2875585ce5f9" />

Root Cause

The status bar separator in ui-tui/src/components/appChrome.tsx (lines ~294-297 and ~335) renders hardcoded ─ characters. On terminal resize:

1. Node.js stdout.on('resize') fires (ui-tui/src/app/useMainApp.ts:413)
2. Ink's AlternateScreen re-renders the full React tree
3. The separator lines are re-drawn at the new terminal size
4. However, Ink's virtual DOM diff does not clear the previous terminal output — old separator characters remain visible while new ones are rendered on top
5. Result: each resize appends one more layer of ghost separators

This is an Ink rendering engine edge case: React's VDOM diff has no awareness of physical terminal geometry changes, so it cannot reconcile "the canvas just got wider/taller" against "the existing screen content needs invalidation."

Environment

• Hermes Agent version: (Hermes Agent v0.12.0 (2026.4.30))
• OS: macOS
• Terminal: (Terminal.app)
• TUI mode: hermes --tui

Request

This is not a feature request for a workaround. The /clear command exists but is a palliative measure — it does not prevent the issue from recurring on the next resize.

The fix should address the root cause: Ink's AlternateScreen must perform a full buffer clear before re-rendering on resize events, or the TUI must explicitly manage resize lifecycle to prevent separator-line accumulation.

Affected code paths:

• ui-tui/src/components/appChrome.tsx:294-297 — leading ─ separator in StatusRule
• ui-tui/src/components/appChrome.tsx:335 — cwd ─ separator
• ui-tui/src/app/useMainApp.ts:405-411 — resize event handler (currently just forwards new column count, does not trigger screen invalidation)

A proper fix would ensure that after any resize event, the TUI renders on a clean slate rather than diffing against stale terminal output.