fix: ghost text post-process strip input prefix + mid-word isolation

- Mid-word: extrait le mot partiel, demande ONLY remaining letters
- Post-process: strip le texte d'entree du debut de la reponse
- Support caracteres accentues dans la regex mid-word
- Prompt plus direct: Complete this word / Continue this text

frontend/editor-poc.html

@@ -1814,14 +1814,23 @@ body { font-family: var(--sans); background: var(--bg); color: var(--text); heig
   }
 
   function requestGhostCompletion() {
-    var text = ta.value.slice(0, ta.selectionStart);
-    if (text.trim().length < 1) return;
-    // Smart prompt: detect if mid-word, mid-phrase, or new block
-    var lastChar = text.slice(-1);
-    var midWord = /[a-zA-Z0-9]$/.test(lastChar);
-    var prompt = midWord
-      ? 'Complete ONLY the current word being typed. Return ONLY the completion (no extra text):\n\n' + text
-      : 'Complete this text naturally in 1-2 short phrases. Return ONLY the new text (no repetition):\n\n' + text;
+    var fullText = ta.value.slice(0, ta.selectionStart);
+    if (fullText.trim().length < 1) return;
+    // Detect context: mid-word vs end of phrase
+    var lastChar = fullText.slice(-1);
+    var midWord = /[a-zA-Z0-9\u00C0-\u024F]$/.test(lastChar);
+
+    // For mid-word: extract the current word and ask AI to complete just it
+    var prompt, inputText;
+    if (midWord) {
+      var wordMatch = fullText.match(/([\w\u00C0-\u024F]+)$/);
+      var partialWord = wordMatch ? wordMatch[1] : fullText;
+      inputText = partialWord;
+      prompt = 'Complete this word. Return ONLY the remaining letters (no spaces, no extra text): ' + partialWord;
+    } else {
+      inputText = fullText;
+      prompt = 'Continue this text. Return ONLY the new text (do NOT repeat what is already written):\n' + fullText;
+    }
 
     fetch('/api/ai/inline-complete', {
       method: 'POST',
@@ -1830,10 +1839,19 @@ body { font-family: var(--sans); background: var(--bg); color: var(--text); heig
     })
     .then(function(r) { if (!r.ok) throw new Error('HTTP ' + r.status); return r.json(); })
     .then(function(data) {
-      var prediction = (data.result || '').trim();
-      // Only show if prediction adds something new
+      var raw = (data.result || '').trim();
+      if (!raw || raw.length < 1) return;
+      // Strip any echoed input from the response
+      var prediction = raw;
+      if (midWord && prediction.toLowerCase().startsWith(inputText.toLowerCase())) {
+        prediction = prediction.slice(inputText.length);
+      } else if (!midWord && prediction.startsWith(inputText)) {
+        prediction = prediction.slice(inputText.length);
+      }
+      prediction = prediction.trim();
+      // Only show if prediction adds something meaningful
       var alreadyThere = ta.value.slice(ta.selectionStart).trimStart();
-      if (prediction && prediction.length > 1 && !alreadyThere.startsWith(prediction.slice(0, Math.min(8, prediction.length)))) {
+      if (prediction && prediction.length > 0 && !alreadyThere.startsWith(prediction.slice(0, Math.min(6, prediction.length)))) {
         showGhost(prediction);
       }
     })