Disable terminal reflow during resize for cmux stability#3
Disable terminal reflow during resize for cmux stability#3lawrencecchen wants to merge 1 commit intomainfrom
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📝 WalkthroughWalkthroughTerminal resize behavior is simplified by disabling reflow and prompt redraw handling during resize operations for both primary and alternate screens. This modification prioritizes content stability and scrollback preservation during aggressive pane resizing. Changes
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| // cmux: preserve terminal content stability across aggressive pane | ||
| // resize churn (especially for SSH-driven shells). Prefer tmux-style | ||
| // no-reflow semantics over potential history loss. | ||
| .reflow = false, |
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Hard-coding reflow = false in Terminal.resize removes the existing DECAWM-dependent behavior and makes primary-screen resize always use no-reflow semantics. This regresses normal terminal behavior outside the cmux scenario: when wraparound is enabled, shrinking or expanding columns no longer reflows soft-wrapped lines (the repository already encodes this expectation in test "Terminal: resize with wraparound on" in src/terminal/Terminal.zig).
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| .reflow = false, | ||
| // cmux: prompt redraw on resize can blank substantial history under | ||
| // repeated split-resize churn. Preserve scrollback over prompt cleanup. | ||
| .prompt_redraw = .false, |
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Setting prompt_redraw = .false unconditionally bypasses the OSC 133 redraw negotiation stored in self.flags.shell_redraws_prompt (set in semanticPrompt), effectively disabling prompt-redraw support for all shells. In sessions where the shell advertises redraw support, resize will no longer clear prompt/input lines before redraw, which can leave stale or duplicated prompt content instead of the intended clean repaint.
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Actionable comments posted: 1
🤖 Prompt for all review comments with AI agents
Verify each finding against the current code and only fix it if needed.
Inline comments:
In `@src/terminal/Terminal.zig`:
- Around line 2729-2735: The patch unconditionally disables reflow and
prompt_redraw in Terminal.zig (the .reflow and .prompt_redraw fields) even
though the comments say this should be cmux-specific; add a compile-time build
option and gate these settings: declare a boolean build option (e.g.,
enableCmux) in src/terminal/build_options.zig, expose it as a comptime/config
constant, and wrap the Terminal.zig assignment so .reflow and .prompt_redraw are
set to false only when that build option is enabled (otherwise keep current
defaults); alternatively, if the intent is global, update the comment and the
tests to reflect that reflow is globally disabled.
| // cmux: preserve terminal content stability across aggressive pane | ||
| // resize churn (especially for SSH-driven shells). Prefer tmux-style | ||
| // no-reflow semantics over potential history loss. | ||
| .reflow = false, | ||
| // cmux: prompt redraw on resize can blank substantial history under | ||
| // repeated split-resize churn. Preserve scrollback over prompt cleanup. | ||
| .prompt_redraw = .false, |
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Scope mismatch: no-reflow is applied globally without a cmux-specific build option.
This change unconditionally hard-disables reflow and prompt redraw for all primary-screen resizes. The comments reference cmux behavior, but no cmux build option exists in the codebase to gate this. This will alter default Ghostty resize semantics globally rather than only for a cmux-specific mode.
The reflow tests ("resize with reflow and saved cursor", etc.) will now silently run with reflow disabled despite their names implying reflow should be active, making them misleading.
To align with the stated cmux-only intent, either:
- Create a cmux build option in
src/terminal/build_options.zigand gate the resize behavior conditionally, or - Clarify that the global behavior change is intentional.
🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed.
In `@src/terminal/Terminal.zig` around lines 2729 - 2735, The patch
unconditionally disables reflow and prompt_redraw in Terminal.zig (the .reflow
and .prompt_redraw fields) even though the comments say this should be
cmux-specific; add a compile-time build option and gate these settings: declare
a boolean build option (e.g., enableCmux) in src/terminal/build_options.zig,
expose it as a comptime/config constant, and wrap the Terminal.zig assignment so
.reflow and .prompt_redraw are set to false only when that build option is
enabled (otherwise keep current defaults); alternatively, if the intent is
global, update the comment and the tests to reflect that reflow is globally
disabled.
Greptile SummaryThis PR modifies the Key concerns:
Recommendation: Either add a cmux-specific build flag, make this a runtime configuration option, or clarify that this is the new default for all users and update documentation/tests accordingly. Confidence Score: 2/5
Important Files Changed
Last reviewed commit: 015b822 |
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| // cmux: preserve terminal content stability across aggressive pane | ||
| // resize churn (especially for SSH-driven shells). Prefer tmux-style | ||
| // no-reflow semantics over potential history loss. | ||
| .reflow = false, |
There was a problem hiding this comment.
This hardcoded reflow = false breaks existing behavior for all Ghostty builds, not just cmux. Previously, reflow was conditional on self.modes.get(.wraparound), respecting user configuration. The PR title mentions "for cmux builds" but there's no build-time or runtime conditional here.
Consider either:
- Adding a build option for cmux and conditionally disabling reflow:
reflow = if (comptime build_options.cmux) false else self.modes.get(.wraparound) - Adding a runtime config option that cmux users can set
- If this is intended for all builds, update the PR description and verify existing tests still pass (e.g., "resize with reflow" tests at lines 12043 and 12085)
| .reflow = false, | ||
| // cmux: prompt redraw on resize can blank substantial history under | ||
| // repeated split-resize churn. Preserve scrollback over prompt cleanup. | ||
| .prompt_redraw = .false, |
There was a problem hiding this comment.
Same issue as above - prompt_redraw = .false is hardcoded for all builds. Previously this was conditional on self.flags.shell_redraws_prompt. Users who configured their terminal to redraw prompts on resize will now have that setting ignored.
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Summary
Disable primary-screen reflow on resize in Ghostty's terminal core for cmux builds.
Why
In SSH sessions under aggressive split resize churn, reflow can corrupt or erase previously drawn content from scrollback. Disabling reflow preserves command output and keeps resize behavior stable (tmux-style).
Change
Screen.resizecall inTerminal.resizetoreflow = falseprompt_redraw = .false) to avoid prompt-region wipes under churnValidation
Validated from cmux integration side with:
tests_v2/test_ssh_remote_resize_scrollback_regression.py(PASS)tests_v2/test_pane_resize_preserves_ls_scrollback.py(PASS)tests_v2/test_pane_resize_preserves_visible_content.py(PASS)Summary by CodeRabbit