41 lines
2.2 KiB
Markdown
41 lines
2.2 KiB
Markdown
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# Background terminal rendering (#3278)
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Inactive panes retain their live terminal and measured dimensions, but move
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outside the viewport. This lets xterm's IntersectionObserver stop painting
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without stopping output parsing or rebuilding the terminal on every tab switch.
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The existing reveal, resize and WebGL recovery paths remain responsible for
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restoring the current screen. No new output queue or lossy truncation is added.
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## Regression coverage
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Run `npm run test:terminal-background-rendering` with a graphical Electron
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session (Linux CI uses xvfb). It bundles the production runtime and inactive
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pane style helper, creates five real terminals, and verifies:
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- The visible terminal paints while all four background terminals do not.
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- Output is already parsed in each hidden terminal and dimensions stay valid.
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- Twelve hide/reveal cycles repaint newly received output.
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- A window-area resize does not collapse the hidden terminal's measured width.
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- Cursor-addressed alternate-screen output survives hiding and a reveal resize.
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- Two visible split panes paint while the remaining hidden panes do not.
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Before this change, the first visibility assertion fails: each background pane
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paints 12 frames instead of zero. The test does not claim to reproduce the
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reporter's delayed high-CPU condition, and direct writes in this harness do not
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exercise the complete SSH/output transport path.
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## Local application validation
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A separate Netcatty development instance with an isolated profile was tested on
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macOS (M2 Max, 32GB), using five real local shell sessions. Four sessions emitted
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continuous logs. The UI was exercised through tab switching, split creation,
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focus mode, detaching back to a tab, closing the extra split, and window resizing.
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Actual screen captures were checked for restored content. CPU comparisons use
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that instance's renderer and GPU process metrics, not other applications.
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This is a CPU optimization for invisible panes. It does not promise lower
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history/GPU memory usage, nor establish the root cause of every #3278 report.
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Remote SSH, Windows/Linux interactive recovery and the reporter's M4 environment
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still require separate validation; this PR should reference rather than close
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that issue automatically.
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