Build & Run output controls

The Build & Run log panel keeps long-running compiler and test output readable without changing or discarding the underlying stream. Three header controls let the user jump to the newest line, decide whether new output should follow automatically, and shorten long lines visually.

Behavior and configuration

• Scroll to bottom is a one-shot action. It moves the current log to its newest line without changing the auto-scroll preference.
• Auto-scroll output is enabled by default. While enabled, each new batch of output keeps the log at the tail. Scrolling upward to read older output pauses auto-scroll so later lines do not pull the view away; enabling it again jumps to the current tail.
• Truncate long lines is disabled by default. When enabled, each long line is displayed on one row with an ellipsis. This is a visual mode only: the full line stays in the log and Copy all output still copies the complete text.

Auto-scroll and visual truncation are stored as device-local application preferences and survive closing and reopening the panel. They are not committed to the repository and do not vary by repository or provider account. The jump action is intentionally not persisted.

The controls have explicit pressed-state semantics and localized accessible names in English and playful Hong Kong Cantonese. Bilingual mode presents both labels through the shared compact bilingual translation layer.

Failure modes and recovery

If saved preference data is absent or invalid, auto-scroll returns to enabled and truncation returns to disabled. Turning truncation off immediately restores normal wrapping. A paused auto-scroll state never pauses the command or output capture; use Scroll to bottom or re-enable auto-scroll to catch up.

Security and data considerations

These controls are renderer-only presentation and navigation choices. They do not alter the command, process, output buffer, repository, or files. Visual truncation does not remove text or conceal it from the existing copy action. As with any build log, copied output can still contain paths or diagnostics from the invoked tool, so review it before sharing.

Verification

build-run-panel-output-controls-test.tsx covers the one-shot jump, explicit toggle state, automatic pause while reading history, resume-at-tail behavior, following only while enabled, persistence, and complete retained line text. The Build & Run style contract covers the pressed state and display-only ellipsis rule. Localization checks cover English, Cantonese, and bilingual composition. The focused Build & Run UI, style, and localization checkpoint passed 42/42 tests; the combined changed-surface gate passed 165/165 across 18 suites.