Move displaced line of top-anchored scroll region into scroll-back by vogella · Pull Request #2764 · eclipse-platform/eclipse.platform

vogella · 2026-06-11T17:05:45Z

Full-screen CLIs such as Codex in --no-alt-screen mode render through DECSTBM scroll regions anchored at the top of the screen and scroll by emitting newlines at the region bottom. The emulator scrolled such a region in place and discarded the displaced top line, so no scroll-back history was created and the output could not be scrolled backwards.

Like xterm and VTE, a newline at the bottom of a scroll region whose top margin is the top of the screen now moves the displaced top line into the scroll-back history, while the lines below the region keep their position on the screen. Regions with a lower top margin still scroll in place, guarded by the characterization tests from #2701; the test documenting the old top-anchored behavior is flipped to assert the history is created.

This addresses the missing backward scrolling reported in #2680.

github-actions · 2026-06-11T18:25:30Z

Test Results

54 files ± 0 54 suites ±0 37m 30s ⏱️ -53s
5 020 tests + 6 4 998 ✅ + 6 22 💤 ±0 0 ❌ ±0
12 951 runs +18 12 797 ✅ +18 154 💤 ±0 0 ❌ ±0

Results for commit 715af39. ± Comparison against base commit a170752.

This pull request removes 1 and adds 7 tests. Note that renamed tests count towards both.

org.eclipse.terminal.internal.emulator.VT100EmulatorBackendTest ‑ testNewlineInTopAnchoredScrollRegionCurrentlyDiscardsTopLine

org.eclipse.terminal.internal.emulator.VT100EmulatorBackendTest ‑ testNewlineInTopAnchoredScrollRegionCoveringWholeScreen
org.eclipse.terminal.internal.emulator.VT100EmulatorBackendTest ‑ testNewlineInTopAnchoredScrollRegionMovesTopLineToHistory
org.eclipse.terminal.internal.emulator.VT100EmulatorBackendTest ‑ testNewlineInTopAnchoredScrollRegionWithFullHistoryDropsOldestLine
org.eclipse.terminal.internal.emulator.VT100EmulatorBackendTest ‑ testNewlineInTopAnchoredScrollRegionWithFullHistoryNotifiesScrollToSnapshots
org.eclipse.terminal.internal.emulator.VT100EmulatorBackendTest ‑ testNewlineInTopAnchoredScrollRegionWithTallFooter
org.eclipse.terminal.internal.model.TerminalTextDataFastScrollTest ‑ testScrollTopAnchoredRegionRepeatedly
org.eclipse.terminal.internal.model.TerminalTextDataFastScrollTest ‑ testScrollTopAnchoredRegionThenGrow

♻️ This comment has been updated with latest results.

stefano-1973 · 2026-06-27T11:08:26Z

It seems to work:

Copilot

🟡 Changes recommended

When history is full and a footer is present, footer scrolling discards the upward-scroll notification, causing selections to be cleared even though the selected text survives.

1 open issue

Preserve selections when scrolling a full history with a footer · New

What changed in this PR

This PR updates the terminal emulator to preserve scroll-back history for top-anchored scroll regions, addressing the missing backward scrolling reported in #2680.

Changes:

Retains displaced top lines in history while keeping footer lines fixed.
Updates the characterization test from #2701 and adds coverage for full history and whole-screen regions.

File	Description
terminal/tests/org.eclipse.terminal.test/src/org/eclipse/terminal/internal/emulator/VT100EmulatorBackendTest.java	Verifies history retention, capacity limits, footer stability, and cursor position.
terminal/bundles/org.eclipse.terminal.control/src/org/eclipse/terminal/internal/emulator/VT100EmulatorBackend.java	Routes top-anchored newline scrolling into history and restores footer positioning.

_{Review effort: Balanced}

akurtakov · 2026-11-04T19:50:10Z

My test which this PR fixes:
In a terminal in the runtime Eclipse, run clear and then vim -u NONE -N --cmd 'set t_ti= t_te=' /etc/services. The --cmd 'set t_ti= t_te=' keeps Vim off the alternate screen, and it has to be --cmd, because with -c Vim has already switched. Hold j (or press Ctrl-E repeatedly) well past the bottom of the screen, then quit with :q and scroll up. Vim scrolls each line with a scroll region over every row except its status line and a newline at the bottom of that region, so on master those lines are thrown away and the history is empty. With #2764 they go into the history, and you'll see /etc/services from its first line (# /etc/services:) onward, above the prompt.

Copilot

🟡 Changes recommended

The scroll optimization leaves stale text in unused ring slots that addLine() later exposes, causing incorrect content when the terminal grows after scrolling.

1 open issue

Restrict scroll rotation to a full ring · New

1 resolved since last review

Preserve selections when scrolling a full history with a footer

_{Review effort: Balanced}

vogella · 2026-11-10T21:33:50Z

My test which this PR fixes: In a terminal in the runtime Eclipse, run clear and then vim -u NONE -N --cmd 'set t_ti= t_te=' /etc/services. The --cmd 'set t_ti= t_te=' keeps Vim off the alternate screen, and it has to be --cmd, because with -c Vim has already switched. Hold j (or press Ctrl-E repeatedly) well past the bottom of the screen, then quit with :q and scroll up. Vim scrolls each line with a scroll region over every row except its status line and a newline at the bottom of that region, so on master those lines are thrown away and the history is empty. With #2764 they go into the history, and you'll see /etc/services from its first line (# /etc/services:) onward, above the prompt.

This statement is hard for me to read, but I think this desribes a positive result of testing the PR.

Planning to merge tomorrow, please clarify in case my understanding of the above it not correct.

Full-screen CLIs such as Codex in --no-alt-screen mode, or Vim kept off the alternate screen, scroll through a DECSTBM region anchored at the top of the screen. The emulator scrolled such a region in place and dropped the displaced top line, so no scroll-back history was created. Like xterm and VTE, a newline at the bottom of such a region now moves the top line into the history while the lines below the region stay in place. With a full history the scroll reaches snapshots as one upward shift, so selections move with the text, and a full TerminalTextDataFastScroll rotates its ring buffer and copies back only the fixed lines instead of the whole history. Regions with a lower top margin still scroll in place. Fixes the missing scroll-back of eclipse-platform#2680 Assisted-by: multiple AI agents and layers of automated tooling 🤖

Copilot

🟢 Approval recommended

No active review issues are reported for the change to preserve scroll-back history while keeping footer lines fixed.

No open issues 🎉

1 resolved since last review

Restrict scroll rotation to a full ring

_{Review effort: Balanced}

akurtakov · 2026-11-11T13:18:54Z

This statement is hard for me to read, but I think this desribes a positive result of testing the PR.

Yes, I have given an exact problem I figured while reviewing another PR that combined with this PR is actually fixed. I haven't reviewed this one in more details.

vogella mentioned this pull request Jun 11, 2026

Codex CLI in an Eclipse IDE terminal doesn't allow backward scrolling (also with --no-alt-screen option) #2680

Open

vogella force-pushed the feature/terminal-scrollregion-history-2680 branch from 56fa99a to e33fdba Compare June 11, 2026 17:40

vogella force-pushed the feature/terminal-scrollregion-history-2680 branch from e33fdba to 1ebdd3e Compare June 12, 2026 13:14

vogella force-pushed the feature/terminal-scrollregion-history-2680 branch from 1ebdd3e to e5b5658 Compare August 4, 2026 17:19

insjang mentioned this pull request Oct 11, 2026

Terminal: keep the screen in the history when it is cleared #2973

Merged

akurtakov force-pushed the feature/terminal-scrollregion-history-2680 branch from e5b5658 to bf72787 Compare November 4, 2026 19:09

akurtakov requested a balanced review from Copilot November 4, 2026 19:10

Copilot started reviewing on behalf of akurtakov November 4, 2026 19:10

View session

Copilot AI reviewed Nov 4, 2026

View reviewed changes

Comment thread ...clipse.terminal.control/src/org/eclipse/terminal/internal/emulator/VT100EmulatorBackend.java Resolved

vogella force-pushed the feature/terminal-scrollregion-history-2680 branch from bf72787 to 9c5d82b Compare November 6, 2026 08:59

vogella requested a balanced review from Copilot November 10, 2026 20:49

Copilot started reviewing on behalf of vogella November 10, 2026 20:49

View session

Copilot AI reviewed Nov 10, 2026

View reviewed changes

Comment thread ...pse.terminal.control/src/org/eclipse/terminal/internal/model/TerminalTextDataFastScroll.java Resolved

vogella force-pushed the feature/terminal-scrollregion-history-2680 branch from 9c5d82b to 715af39 Compare November 11, 2026 12:26

vogella requested a balanced review from Copilot November 11, 2026 12:41

Copilot started reviewing on behalf of vogella November 11, 2026 12:42

View session

Copilot AI reviewed Nov 11, 2026

View reviewed changes

vogella merged commit e0f2183 into eclipse-platform:master Nov 11, 2026
18 checks passed

Navigation Menu

Repository navigation

Move displaced line of top-anchored scroll region into scroll-back - #2764

Move displaced line of top-anchored scroll region into scroll-back#2764
vogella merged 1 commit into
eclipse-platform:masterfrom
vogella:feature/terminal-scrollregion-history-2680

vogella commented Jun 11, 2026

Uh oh!

github-actions Bot commented Jun 11, 2026 •

edited

Loading

Uh oh!

stefano-1973 commented Jun 27, 2026

Uh oh!

Copilot AI left a comment

Uh oh!

Uh oh!

akurtakov commented Nov 4, 2026 •

edited

Loading

Uh oh!

Copilot AI left a comment

Uh oh!

Uh oh!

vogella commented Nov 10, 2026

Uh oh!

Copilot AI left a comment

Uh oh!

akurtakov commented Nov 11, 2026

Uh oh!

Uh oh!

Reviewers

Uh oh!

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

Conversation

vogella commented Jun 11, 2026

Uh oh!

github-actions Bot commented Jun 11, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Test Results

Uh oh!

stefano-1973 commented Jun 27, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

🟡 Changes recommended

Uh oh!

Uh oh!

akurtakov commented Nov 4, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

🟡 Changes recommended

Uh oh!

Uh oh!

vogella commented Nov 10, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

🟢 Approval recommended

Uh oh!

akurtakov commented Nov 11, 2026

Uh oh!

Uh oh!

Reviewers

Uh oh!

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

github-actions Bot commented Jun 11, 2026 •

edited

Loading

akurtakov commented Nov 4, 2026 •

edited

Loading