Group ordinary typing and deletion into useful undo steps

[owainlewis]

Group ordinary typing and deletion into useful undo steps

What are we building?

Every typed character is currently a separate undo step. Group contiguous typing and deletion while keeping intentional commands separate and preserving save/reload history.

Why?

This removes a concrete obstacle to the local coding loop tracked in #160 while keeping Cortex small and predictable.

Done when

• Contiguous ordinary typing is reversed by one undo, and contiguous backward/forward deletion groups by direction.

• Movement, prompts, buffer switches, save, newline, paste, indentation, kill/yank, and undo/redo end the current typing group.

• A pause of at least 750 ms ends a typing group; tests use an injected clock or explicit timestamps.

• Undo restores the original point; redo restores the complete group; new editing after undo discards only the redo branch.

• Saved-state and changed-line markers remain correct across groups, save, undo, redo, and Unicode edits.

• Retained undo/redo text payload is limited to 16 MiB per buffer by evicting oldest whole groups; preserve the newest group even when it alone exceeds the budget, and keep dirty-baseline identity correct after eviction.

How to check

cargo test buffer::; cargo test app::; cargo test commands::; cargo fmt --check; cargo clippy --all-targets -- -D warnings; cargo test. Type a word, move, type another, undo/redo each step, save, and exit.

Agent notes

• Depends on: Indentation and terminal paste.
• Source: Deliver a minimalist daily coding editor #160 and the product direction in docs/prd.md. Keep macOS-only behavior, Ropey storage, view-owned point/scroll, and the renderer boundary. Preserve dirty-buffer, atomic-save, disk-change, and grapheme-boundary guarantees.
• Keep a linear history. Do not merge edits across a clean save boundary or replace precise structural edit metadata with whole-file snapshots.

[owainlewis]

Implemented grouped typing and deletion with explicit 750 ms timing, deliberate-command and buffer-switch boundaries, saved-state preservation, and whole-group eviction above a 16 MiB text payload budget.

The real terminal smoke uncovered and reproduced an existing C-/ and C-_ shortcut failure: Crossterm emits C-7 for the legacy byte. The alias is fixed and covered by a PTY regression. Formatting, strict Clippy, release build, 371 unit tests, the new terminal regression, and the release editing smoke pass. Independent review approved both changes. The two known redirected-input tests remain sandbox-limited locally and will be verified by CI before merge.

[owainlewis]

Merged in #180 as ba31366.

Typing and same-direction deletion now undo in groups with a 750 ms pause boundary, deliberate-command boundaries, preserved saved-state markers, and a 16 MiB retained text budget with whole-group eviction. The legacy C-/ and C-_ terminal shortcut is also fixed and covered by a regression that failed before the fix.

Verification: formatting, strict Clippy, release build, 371 unit tests, and all 13 terminal integration tests passed in macOS CI. The release PTY session passed typing separated by movement and pauses, both deletion directions, undo/redo across saves, and shell restoration. Fresh independent review approved all changes; automated review completed with its roadmap comment answered using the prior paste merge.