Text: Ctrl+arrows, Ctrl+Backspace/Delete and the other text keys work like PowerPoint (#268)

Observed black-box in PowerPoint for Windows on synthetic text:
- Word stops (crates/model/src/words.rs): words, punctuation runs, symbol
  runs, tabs, line breaks and each CJK character are tokens; trailing spaces
  join the token before. it's, a-b, 3.14, 1,000 are one word; e.g., a_b and
  x@y.com are not. Grapheme clusters never split.
- Ctrl+Left/Right and Ctrl+Shift+Left/Right move by those stops, across
  paragraphs; with a selection they go on from its start/end. In a
  right-to-left paragraph Left and Right swap.
- Ctrl+Backspace deletes to the previous stop; Ctrl+Delete deletes the rest
  of the word, or spaces plus the next word, then applies PowerPoint's smart
  spacing. With a selection both work from its start.
- Ctrl+Up/Down by paragraph, Ctrl+Home/End to the text's ends.
- End on a wrapped line goes past the trailing space and the caret stays
  drawn at that line's end (TextSel::line_end); End again stays, Home
  returns to the same line.
- Ctrl+]/[ and Ctrl+Shift+>/< change font size (egui's Period/Comma/
  bracket key names now match registry shortcuts).
- Shift+F3 cycles lower -> Title -> UPPER; a caret changes its word.
- Double-click selects the word without trailing spaces; triple-click
  includes the paragraph mark.
- Mac keeps Option for words and Cmd for line/text ends (Session::mac_keys).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docs/ui-parity.md

@@ -2,6 +2,8 @@
 
 > **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-12 · **Change:** minor (off-slide objects in Normal view, #270) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 
+> **Last reviewed:** 2026-10-12 · **Last updated:** 2026-10-12 · **Change:** minor (text editing keys observed in PowerPoint for Windows, #268) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
+
 How DeckCraft looks and feels next to PowerPoint: the shell, the ribbon, menus, panes, dialogs,
 direct manipulation, keyboard and precision. Observations of PowerPoint are kept locally in
 `plan/powerpoint/01-observed-ui.md` and `menu-tree.txt` (gitignored, clean-room rules in
@@ -64,6 +66,35 @@ group/ungroup, bold/italic/underline, alignment, font size, list levels, Format
 start/current, view switching. Not yet: Cmd+F Find opening a find bar on the slide, Option+drag
 precision without snapping, F6 pane cycling, ribbon KeyTips (Windows).
 
+### Text editing keys
+
+Observed black-box in PowerPoint for Windows (Microsoft 365, October 2026) on synthetic text, and
+pinned by tests in `crates/model/src/words.rs`, `crates/model/src/edit.rs` and
+`crates/engine/src/tests_keys.rs` (#268). Windows and Linux use Ctrl; the Mac uses Option for words
+and Cmd for line and text ends (`Session::mac_keys`).
+
+| Keys | Behaviour |
+|---|---|
+| Ctrl+Left / Right | Previous / next word stop. A stop is the start of every word, punctuation run, symbol run, tab, line break and CJK character, plus the paragraph's end; spaces belong to the word before them. `it's`, `baz-qux`, `a-`, `3.14`, `1,000`, `3:45` are one word; `e.g.`, `a_b`, `x@y.com`, `dogs'` are not. Every CJK ideograph, kana and Hangul syllable is a word. Combining marks and emoji sequences never split. With a selection: Right goes on from its end, Left from its start |
+| Ctrl+Shift+Left / Right | Moves the selection's moving end by the same stops |
+| Ctrl+Up / Down | Start of the paragraph (then of the previous one) / start of the next paragraph (end of the text in the last one); Shift extends |
+| Ctrl+Backspace | Deletes back to the previous stop (word plus its trailing spaces); at a paragraph's start joins it to the previous paragraph |
+| Ctrl+Delete | Inside a word: the rest of it. On spaces after a word: the spaces and the next word. At a word's start: the word and its spaces. Then smart spacing: spaces left before closing punctuation (`ab cd, ef` → `ab, ef`) or at the paragraph's end after a word go; sentence punctuation left touching a word gets a space (`cd...ef gh` → `cd... gh`). At a paragraph's end joins the next paragraph |
+| Ctrl+Backspace / Delete with a selection | Leave the selection and delete the word part before / after its start |
+| Right-to-left paragraph | Left and Right (with or without Ctrl) swap: Left goes forward in the text. Arabic or Hebrew words in a left-to-right paragraph move in logical order |
+| Home / End | Start / end of the visual line. End on a wrapped line goes past its trailing space and the caret stays drawn at that line's end; End again stays; Home from there returns to the same line's start |
+| Ctrl+Home / End | Start / end of the text; Shift extends |
+| Ctrl+Shift+> / <, Ctrl+] / [ | Next / previous size in the font size list (18 → 20 → 24) |
+| Ctrl+B / I / U, Ctrl+Space | With a caret strictly inside a word, the whole word (without trailing spaces); at a word's edge, only what is typed next |
+| Ctrl+E / L / R / J | Center / left / right / justify the paragraphs in the selection |
+| Shift+F3 | Cycles lowercase → Capitalize Each Word → UPPERCASE → lowercase; other mixes go to UPPERCASE first. A caret in a word changes that word and moves to its start |
+| Shift+Enter | Line break |
+| Double-click / triple-click | The word without its trailing spaces (a CJK character on its own) / the paragraph including its paragraph mark |
+
+Quirks kept on purpose because PowerPoint has them: Ctrl+Left (not Ctrl+Right) also stops at
+each no-break or ideographic space, and treats an emoji followed by punctuation as one word. Tab, Shift+Tab and
+Alt+Shift+arrows in text are handled elsewhere (#78, #93).
+
 ## Visual fidelity
 
 Colours, spacing, ribbon card and tab geometry follow the observations in
@@ -91,4 +122,6 @@ imitate Microsoft's. No pixel comparison against PowerPoint screenshots has been
 | 2026-10-12 | minor | Off-slide objects drawn and editable around the slide in Normal view (#270) |
 
 | 2026-10-12 | minor | Selection Pane matched to PowerPoint (#133): drag and drop, arrows, groups, eye, Lock |
+
+| 2026-10-12 | minor | Text editing keys: Ctrl+arrows, Ctrl+Backspace/Delete, Ctrl+Up/Down, Home/End on wrapped lines, Shift+F3, font size keys, as observed in PowerPoint for Windows (#268) |
 | 2026-10-10 | major | Created: shell, panes and dialogs, direct manipulation, shortcuts and visual fidelity against PowerPoint 16.113 |