fix: Short sentence instruction + chunker splits instead of truncating

- Added CRITICAL instruction to keep sentences under 150 chars
- Chunker now splits long sentences at word boundaries instead of truncating
- No words lost when splitting

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

meshai/chunker.py

@@ -77,8 +77,14 @@ def chunk_response(
                 current_len = 0
                 # Don't increment sentence_idx — retry this sentence in next message
             else:
-                # Single sentence exceeds max_chars — truncate it
-                messages.append(sentence[:max_chars])
+                # Single sentence exceeds max_chars — split at last word boundary
+                break_point = sentence[:max_chars].rfind(' ')
+                if break_point <= 0:
+                    break_point = max_chars
+                messages.append(sentence[:break_point].rstrip())
+                leftover = sentence[break_point:].lstrip()
+                if leftover:
+                    sentences.insert(sentence_idx + 1, leftover)
                 sentence_idx += 1
 
     # Flush any remaining buffered message

meshai/router.py

@@ -102,6 +102,7 @@ RESPONSE STYLE:
 - Include scores, percentages, node counts, battery levels, gateway counts
 - You CAN use 3-5 messages if needed — LoRa chunking handles splitting
 - No markdown formatting — plain text only
+- CRITICAL: Keep every sentence under 150 characters. Break long thoughts into multiple short sentences. The message system handles multiple sentences perfectly but will truncate a single long sentence.
 
 ANSWERING COVERAGE QUESTIONS:
 - Reference geographic areas by local name from the region config