Prompt-aware text selection at the shell prompt (terminal.promptSelection) by azooz2003-bit · Pull Request #17706 · manaflow-ai/cmux

azooz2003-bit · 2026-10-06T20:05:50Z

Layer 2 of #13915: text-field selection at a shell prompt, behind a new setting terminal.promptSelection (off by default, next to terminal.textEditingGestures). With it on, at a prompt with shell integration:

Cmd+A selects only the command you're typing. On an empty prompt it keeps today's select-all.
Shift+Left/Right extend by one character, Cmd+Shift+Left/Right to the start or end of the input.
Cmd+C copies through the normal copy path. Cmd+X copies the selection's exact text, then deletes it.
Typing, Backspace or Delete replace the selection.
Plain Left/Right collapse the selection. Collapsing never presses Right, so it can't accept a zsh autosuggestion.

Inside vim, less or any alternate-screen app, while a command runs, or without shell integration, every key behaves exactly as it does today.

How it works

The Ghostty fork now exports where the input is (manaflow-ai/ghostty#235, with #237 and #238 so a right prompt and the spaces zle writes to erase text don't count; all merged, submodule at e1b8bf5f478c6aadbf70e51cdbb41930e92fda10, which also includes merged manaflow-ai/ghostty#236 and #239):

bool ghostty_surface_prompt_input(ghostty_surface_t, ghostty_surface_prompt_input_s*); // length, caret, selection inside input
bool ghostty_surface_select_prompt_input(ghostty_surface_t, uint32_t start, uint32_t end); // no clipboard write

Offsets are caret stops: .input cells holding text, wide spacers skipped, so one stop is one arrow press for zle or readline. The export refuses the alternate screen, a running command, a line with no prompt before its input (fzf --height and completion menus draw in input mode), and a line with a multi-codepoint grapheme. The input ends at the first empty cell at or after the cursor, because zle draws RPROMPT after OSC 133 B by moving across the gap, so a right prompt is .input text. Spaces after the cursor that run into that end are dropped too, since with RPROMPT shown zle erases deleted text by writing spaces.

The pure resolver (TerminalPromptSelection.swift, 25 tests) turns a gesture plus that snapshot into pass-through, consume, select, clear, or an arrow+Backspace edit. GhosttyNSView calls it from two places:

performKeyEquivalent matches Cmd+A and Cmd+X (layout-normalized) ahead of Ghostty's select_all binding. It waits behind an in-flight clipboard read.
keyDown, ahead of the text-editing gestures, handles Shift+arrows, and while cmux holds a prompt selection, the keys that collapse or replace it. With no held selection, ordinary typing pays one nil check and a key-code compare; the defaults read and the Ghostty call happen only for gestures.

Edits are replayed as Left/Right/Backspace presses through sendGhosttyKey, so Ghostty encodes them for whatever keyboard protocol is active (same reasoning as #13921). The two C calls live in CmuxTerminalCore (TerminalPromptInputSnapshot.read(from:), TerminalPromptSelection.select(on:)), which compiles against GhosttyKit's own module; the package test runners get weak stubs for them.

Decided defaults and known limits

zsh-autosuggestions: its ghost text is drawn right after the buffer as .input cells, and Ghostty can't tell it apart cheaply, so Cmd+A at the end of a line selects the suggestion too. Right never accepts it while a selection is active, because collapsing never presses Right. An edit that reaches into the suggestion (Shift+Right past the buffer, then Backspace) presses Right once, which accepts the whole suggestion first.
Multi-line input: soft-wrapped rows are all selectable. A hard newline in a multi-line buffer takes no cell, so only the cursor's line counts (Cmd+A on line 2 selects line 2).
Option+Shift word selection: out of scope. It needs the input text, which the export doesn't provide.
Keymaps: edits assume an emacs-style line editor. cmux can't know the keymap, so in vi command mode the replayed Backspace moves instead of deleting.
Control characters: zle shows a control character as ^X in two cells, so an edit across it sends one Backspace too many.
OSC 133 from TUIs on the main screen: accepted; the running-command check already covers most cases.
A selection outside the input (output selected with the mouse) keeps Ghostty's own Shift+arrow adjust_selection, and typing never replaces a selection cmux didn't make.

Settings: catalog, cmux.json path, schema (docs page renders from it), Settings row, search index and aliases, all-keys.md, and the three new strings in all nine macOS locales (localization_catalog.py check: 0 parity errors).

Catch-up and review fix

Merged main at 478e3232b0991564a380a4d67b5e55c60dc2aa3b using the repository merge helper. Selection anchors now clear on non-selection input and terminal surface replacement, so Shift+Left after collapse and paste starts at the current caret rather than a stale offset. Regression tests were committed in bca0fc73b1f9a497e4b461d76c6a810a059962e7, followed by the fix in 70c339a9848da78137ad16e6d4a5421bb59969c4.

On that head, macOS compile admission and swift-package-tests passed in CI run 36689103816. Both new tracker tests executed and passed. The pre-fix test commit was not executed, so no red-before result is claimed. App-host tests are still running. The CLI lane failed only in the unchanged Codex monitor memory test at its five-second parser-checkpoint deadline; a rerun will follow when the workflow finishes. Vercel previews failed before building because the repository did not contain the requested fork reference.

A review subagent found no confirmed correctness defect. The remaining coverage limitation is that tracker tests do not drive the AppKit paste or surface-attach methods directly. The prompt-input stubs stay in package test targets only; they are needed to link tests without starting Ghostty and are not a runtime workaround.

Changelog

Added: optional shell-prompt selection with keyboard gestures, copy, cut, and selection replacement.

Validation (earlier head)

Ghostty: eleven promptInput Zig tests ran in build-ghosttykit.yml before packaging at b93ab4222 (run 36319683313: 84/84 with the filter vs 74 for the single-test pacer filter), which also published the xcframework; its checksum is pinned. This PR adds that test step to the workflow.
CI on e8af053: macOS compile admission, app-host unit tests (changed suites) and CLI product tests passed. swift-package-tests passed every package including CmuxTerminalCore (the "Terminal prompt selection resolver" suite, 23 tests), CmuxTerminal and CmuxCloudTui. The first attempt failed only in CmuxSimulator ("Closing the parent pipe writer delivers output through EOF", a package this PR doesn't touch); the rerun passed.
Calling the exports straight from GhosttyTerminalView compiled on some runners and failed on others with the new declarations missing. The app sees Ghostty's C API through the ghostty.h bridging header, and a seeded DerivedData's bridging PCH (regenerated in 0.06 s) predates the submodule bump. Moving the calls into CmuxTerminalCore fixed it; the seeding gap itself will bite the next Ghostty header change that app code uses directly.
Local guards (scripts/ci/guards-local.sh, 66 steps) pass on the head.
Two review passes by subagents. Fixed: right prompts and zle's erase spaces counted as input (the two Ghostty follow-ups), a whitespace-only Cut writing an empty clipboard and trimmed Cut text, Cmd+A/Cmd+X jumping ahead of a pending paste, Shift-arrows stealing an output selection, non-Latin layouts.

Dogfood

CI dogfood tour run 36736813041 passed on the pre-catch-up head 1cf4acb. The tour shows typed prompt input, Shift+Left selecting world, Cmd+A selecting only the input, and typing replacing the selection. The latest catch-up merges main through b3d644b; the prompt-selection code and tour are unchanged. The package tests exercise tracker invalidation, not the AppKit paste or attach paths. Checks to run in zsh with shell integration and the setting on:

Type echo hello world, Cmd+A: only the input highlights, not the prompt or output. pbpaste unchanged.
Shift+Left ×5 from the end: world highlights; Shift+Right ×2 shrinks it; Cmd+Shift+Left extends to the start.
Cmd+C, then pbpaste shows exactly the highlighted text.
Cmd+A, Cmd+X: input empties, pbpaste has it; select one space and Cmd+X: the clipboard holds a space, never empty.
Select part of the input and type x: the selection is replaced; Backspace and Delete remove a selection.
Left/Right with a selection: collapses without moving past the end; with zsh-autosuggestions showing a suggestion, Cmd+A then Right doesn't accept it.
With RPROMPT='%~': Cmd+A and Cmd+Shift+Right never select the right prompt; type git status, Backspace to git, Shift+Right selects nothing past git, and no edit deletes unselected characters.
Empty prompt, Cmd+A: selects everything as before.
In vim and less: Cmd+A, Shift+arrows, typing behave exactly as with the setting off.
Setting off: Cmd+A selects all, Shift+arrows unchanged.
Mouse-select output, then Shift+Left: Ghostty's selection adjusts; the prompt isn't touched.
Record a full-screen video of 1–7.

🤖 Generated with Claude Code

Screenshots

The cropped frames below come from the passing CI dogfood tour run 36736813041.

Please check copy/paste on the dev-build link. This PR is from teamleaderleo/cmux, so a dev-build link is unavailable because that label only works for branches in manaflow-ai/cmux.

The PR is caught up through main at b3d644ba87324ef330080fda68db5b7f61b6fcc8; the final branch head is e406d4d8009cd17c022d3ed90825e4bc4e47e278.

Migrated from #14856 after correcting the PR author identity. The head branch and commit history are preserved.

Summary by cubic

Layer 2 of #13915: adds text-field selection at the shell prompt, behind a new terminal.promptSelection setting (off by default, next to terminal.textEditingGestures). At a prompt with shell integration, Cmd+A now selects only the command being typed instead of the whole terminal, while Shift-arrows, Cut, Delete, and typed text extend or replace the selection; outside a prompt (alternate-screen apps, running commands, no shell integration) every key behaves exactly as before.

New Features

Cmd+X copies the selection's exact untrimmed text before deleting; an empty prompt keeps today's whole-terminal select-all.
Plain Left/Right collapse a selection without ever pressing Right, so collapsing can't accept a zsh autosuggestion.
Edits replay arrow and Backspace keys through Ghostty's key path so the active keyboard protocol encodes them.
Selection assumes an emacs-style line editor; in vi command mode the replayed Backspace moves instead of deleting, and editing across a control character (shown as ^X in two cells) sends one Backspace too many.
A zsh autosuggestion's ghost text is drawn as input cells, so Cmd+A at the end of a line selects it, and only the cursor's line of a multi-line buffer is selectable.

Dependencies

The Ghostty submodule now exports the prompt-input and selection C APIs; its promptInput Zig tests run in build-ghosttykit.yml and the xcframework checksum is pinned.
The setting is wired through the catalog, JSON config path, schema, Settings UI row, search index and aliases, docs, and all nine macOS locales.

^{Written for commit d1176dd. Summary will update on new commits.}

Summary by CodeRabbit

New Features
- Added an optional Prompt Text Selection setting, off by default. When enabled, select shell prompt text with Command-A or Shift+arrow, then replace or delete the selection, or cut it with Command-X.
- The feature requires OSC 133 shell integration and works at prompts on the main screen—not while commands are running or inside full-screen terminal apps.
Documentation
- Added guidance on the setting’s availability and behavior.

Pure decision logic for Layer 2 of #13915: given the shell input under the cursor (caret stops, caret, input selection) it resolves Select All, Shift/Cmd+Shift+arrow extension, Cut, Delete and typed text into a select, clear, or arrow+backspace edit, and passes everything through when there is no prompt state. Wiring waits on the Ghostty prompt-input export. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>