Preserve preview harness, editor, email and task improvements

Snapshot current maintainer-preview application changes and regression fixtures for integration into lab. Excludes local runtime data, evaluation outputs and source backups. Focused Python regression selection: 140 passed; full suite not certified.

src/email_attachment_text.py

@@ -0,0 +1,56 @@
+"""Bounded local previews of already-authorized email attachments."""
+from pathlib import Path
+
+
+def attachment_text(path, *, max_chars=12000):
+    path = Path(path)
+    if path.stat().st_size > 20 * 1024 * 1024:
+        return {'content_status': 'too_large', 'content_note': 'Attachment exceeds the 20 MB reading limit.'}
+    suffix = path.suffix.lower()
+    parts = []
+    truncated = False
+    try:
+        if suffix == '.pdf':
+            from pypdf import PdfReader
+            reader = PdfReader(path)
+            if reader.is_encrypted and not reader.decrypt(''):
+                return {'content_status': 'encrypted', 'content_note': 'PDF requires a password.'}
+            for number, page in enumerate(reader.pages):
+                if number >= 50 or sum(map(len, parts)) >= max_chars:
+                    truncated = True
+                    break
+                parts.append(f'Page {number + 1}:\n' + (page.extract_text() or ''))
+            if not any(part.split(':\n', 1)[-1].strip() for part in parts):
+                return {'content_status': 'needs_ocr', 'content_note': 'No embedded PDF text. Scanned pages require OCR; contents have not been read.'}
+        elif suffix in {'.txt', '.md', '.csv', '.tsv', '.json', '.xml', '.log'}:
+            with path.open(encoding='utf-8', errors='replace') as file:
+                parts.append(file.read(max_chars + 1))
+        elif suffix == '.docx':
+            from docx import Document
+            doc = Document(path)
+            parts.extend(p.text for p in doc.paragraphs)
+            for table in doc.tables:
+                parts.extend('\t'.join(cell.text for cell in row.cells) for row in table.rows)
+        elif suffix == '.xlsx':
+            from openpyxl import load_workbook
+            book = load_workbook(path, read_only=True, data_only=True, keep_links=False)
+            try:
+                for sheet in book:
+                    parts.append(f'Sheet: {sheet.title}')
+                    for index, row in enumerate(sheet.iter_rows(values_only=True)):
+                        if index >= 1000 or sum(map(len, parts)) >= max_chars:
+                            truncated = True
+                            break
+                        parts.append('\t'.join('' if cell is None else str(cell) for cell in row))
+                    if truncated:
+                        break
+            finally:
+                book.close()
+        else:
+            return {'content_status': 'unsupported', 'content_note': 'This attachment format has no inline text reader.'}
+        text = '\n'.join(parts).strip()
+        truncated |= len(text) > max_chars
+        return {'content': text[:max_chars], 'content_status': 'read' if text else 'empty',
+                'content_note': 'Preview truncated; remaining content was not read.' if truncated else ''}
+    except Exception as exc:
+        return {'content_status': 'failed', 'content_note': f'Attachment text extraction failed ({type(exc).__name__}); contents have not been read.'}