fix(输入法): 修复光标间隙并扩大26键及明确大小写切换

com.sydxky.rtos.inputmethod/tests/engine.test.mjs

@@ -2,7 +2,7 @@ import fs from 'node:fs'
 import path from 'node:path'
 import assert from 'node:assert/strict'
 import {fileURLToPath} from 'node:url'
-import {createDictionary,digitsOf,code14Of,KEY14_GROUPS,display14,candidatePages,edit,erase,preview,learn,sanitizePreferences,chars} from '../src/common/ime-engine.js'
+import {createDictionary,digitsOf,code14Of,KEY14_GROUPS,display14,candidatePages,edit,erase,preview,previewParts,learn,sanitizePreferences,chars} from '../src/common/ime-engine.js'
 const root=path.resolve(path.dirname(fileURLToPath(import.meta.url)),'../src')
 let count=0
 function check(ok,label){assert.ok(ok,label);count++}
@@ -55,6 +55,12 @@ check(erase('你😀好',2).text==='你好','Unicode backspace preserves surroga
 check(edit('你好',2,'世界',3).limited,'maximum length enforced')
 check(!preview('my-secret',5,true).includes('secret'),'secret preview masked')
 check(chars('😀').length===1,'Unicode length counts codepoints')
+check(previewParts('不',1,false).before==='不'&&previewParts('不',1,false).after==='','end cursor has no inserted spacer or font-glyph advance')
+check(previewParts('你😀好',2,false).before==='你😀'&&previewParts('你😀好',2,false).after==='好','middle cursor splits at a Unicode codepoint boundary')
+check(previewParts('你好',0,false).before===''&&previewParts('你好',0,false).after==='你好','start cursor precedes text without padding')
+check(previewParts('a b',2,false).before==='a '&&previewParts('a b',2,false).after==='b','intentional spaces are preserved')
+check(!JSON.stringify(previewParts('my-secret',5,true)).includes('secret'),'split preview masks password on both sides')
+check(chars(previewParts('长😀'.repeat(1000),1000,false).before).length<=8&&chars(previewParts('长😀'.repeat(1000),1000,false).after).length<=8,'long preview keeps the real cursor inside round-screen width')
 dictionary.clear();check(dictionary.cacheSize===0,'cache release')
 check((await dictionary.lookup('niha',false,{}))[0].word==='你好','unfinished pinyin completes a real word before shorter fallback')
 check((await dictionary.lookup(digitsOf('niha'),true,{}))[0].word==='你好','unfinished T9 shares the completion policy')