collapse command output

Collapsible Command Output

Date: 2026-07-20
Tracking: Issue #80; sub-issues #81, #82, #83
Status: Approved for implementation in PR #84

Corrected design

• Command output starts collapsed once the buffered text exceeds three logical lines or 4,096 characters.
• Raw text stays in an extension-side, non-DataMember incremental buffer. Remote UI receives only the preview while collapsed and the buffered full text while expanded.
• The preview contains at most three logical lines and 4,096 characters. Appends scan only the new suffix, including CRLF split across chunks.
• The UI uses the standard WPF Expander, TwoWay IsExpanded, VS theme resources, keyboard focus, and the standard ExpandCollapse automation pattern.
• Preview and expanded text are monospace, no-wrap, and horizontally scrollable.
• When worker truncation occurs, labels describe buffered output and never claim a complete line count.
• No OSS or NuGet control is required.

Verification

• Cover 0/1/3/4 lines, empty lines, trailing newline, split CRLF, streaming, expanded appends, re-collapse, a single line over 4,096 characters, and truncation.
• Assert that collapsed streaming does not publish the full buffer or rescan it on every delta.
• Verify DataMember coverage, XAML bindings, VS theme resources, keyboard operation, and accessibility semantics.