add prewie to filemanger

prg/SJNet_filemanager.py

@@ -4,16 +4,29 @@
 Keys:
     Up/Down  or  k/j    Navigate
     Enter                Open (folder -> cd, file -> menu)
+    v  or  Tab           Toggle the preview pane for the selected entry
+    f                    Open the selected text file in the full-screen viewer
     /                    Search (live filter while typing)
     Backspace  or  h     Go to parent directory
+    g / G                Jump to top / bottom of the list
+    PgUp / PgDn          Scroll the list a page at a time
+    ~                    Jump to the home directory
+    s                    Cycle sort order (name / size / mtime)
     .                    Toggle hidden files
     r                    Rename selected entry
     d                    Delete selected entry (asks for confirmation)
     n                    Create a new folder
+    t                    Create a new empty file
     c / x                Mark selected entry as copy / move source
     p                    Paste the marked entry into the current folder
     q                    Quit
 
+Preview pane (v / Tab): shows the first ~50 lines of the text file under
+the cursor, a rendered view of Markdown files (headings, bold, italic,
+inline code, code blocks, lists, block quotes, simple [text](url) links),
+a sizes listing for folders, or "(binary)" otherwise. j/k scroll the
+preview when it is open.
+
 Symlinks to folders and files are followed: folder links can be entered
 like real directories. Broken symlinks are not listed.
 """
@@ -21,15 +34,38 @@ like real directories. Broken symlinks are not listed.
 import curses
 import locale
 import os
+import re
 import shlex
 import shutil
 import subprocess
+import time
 from collections.abc import Callable
 from pathlib import Path
 
 
 PARENT = Path("..")
 
+# Preview settings: how many lines of a text file to show.
+PREVIEW_LINES = 50
+# Files larger than this are treated as "too big" for the preview.
+PREVIEW_MAX_BYTES = 2 * 1024 * 1024
+# Extensions considered (probably) plain text for the preview.
+TEXT_EXTENSIONS = {
+    ".txt", ".md", ".markdown", ".rst", ".log", ".ini", ".cfg", ".conf",
+    ".toml", ".yaml", ".yml", ".json", ".xml", ".html", ".css",
+    ".py", ".js", ".ts", ".java", ".c", ".h", ".cpp", ".hpp", ".rs",
+    ".go", ".php", ".rb", ".sh", ".bash", ".zsh", ".fish", ".ps1",
+    ".sql", ".lua", ".vim", ".dockerfile", ".gitignore", ".csv",
+    ".service", ".desktop", ".env", ".text",
+}
+# Filenames (without extension) that are usually plain text.
+TEXT_FILENAMES = {
+    "readme", "license", "changelog", "todo", "makefile", "dockerfile",
+    ".gitignore", ".gitattributes", ".editorconfig", ".env",
+}
+
+SORT_MODES = ("name", "size", "mtime")
+
 
 # ---------- helpers ---------------------------------------------------------
 
@@ -134,6 +170,279 @@ def format_entry(name: str, is_dir: bool, full_path: Path, width: int) -> str:
     return label[:width].ljust(width)
 
 
+def sort_entries(
+    items: list[Path], mode: str
+) -> list[Path]:
+    """Sort a list of entry paths (already without the '..' entry)."""
+    if mode == "size":
+        def key(e: Path) -> tuple:
+            try:
+                if e.is_dir(follow_symlinks=True):
+                    return (0, 0, e.name.lower())
+                return (0, e.stat().st_size, e.name.lower())
+            except OSError:
+                return (0, -1, e.name.lower())
+    elif mode == "mtime":
+        def key(e: Path) -> tuple:
+            try:
+                return (0, -e.stat().st_mtime, e.name.lower())
+            except OSError:
+                return (0, 0, e.name.lower())
+    else:
+        def key(e: Path) -> tuple:
+            return (0, 0, e.name.lower())
+    return sorted(items, key=key)
+
+
+def is_text_file(path: Path) -> bool:
+    """Heuristic: does this look like a plain-text file we can preview?"""
+    try:
+        st = path.stat()
+    except OSError:
+        return False
+    if st.st_size == 0:
+        return True  # empty files are trivially "text"
+    name = path.name.lower()
+    if path.suffix.lower() in TEXT_EXTENSIONS or name in TEXT_FILENAMES:
+        return True
+    if name == "dockerfile" or name.startswith("dockerfile."):
+        return True
+    if st.st_size > PREVIEW_MAX_BYTES:
+        return False
+    # Sniff: read a small chunk and look for NUL bytes / too many weird bytes.
+    try:
+        with path.open("rb") as fh:
+            chunk = fh.read(8192)
+    except OSError:
+        return False
+    if not chunk:
+        return True
+    if b"\x00" in chunk:
+        return False
+    weird = sum(1 for b in chunk if b < 9 or (13 < b < 32))
+    return weird / len(chunk) < 0.10
+
+
+def read_preview_lines(path: Path) -> tuple[list[str], str, bool]:
+    """Read the first PREVIEW_LINES lines of a text file.
+
+    Returns (lines, error, truncated). `lines` always has the raw text
+    (undecorated); error is "" on success or a short message; truncated is
+    True when the file has more lines than were returned.
+    """
+    try:
+        st = path.stat()
+    except OSError as e:
+        return [f"(cannot stat: {e})"], "err", True
+    if st.st_size > PREVIEW_MAX_BYTES:
+        return (
+            [f"(file too large for preview: {human_size(st.st_size)})"],
+            "err",
+            True,
+        )
+    try:
+        with path.open("r", encoding="utf-8", errors="replace") as fh:
+            lines = []
+            for i, line in enumerate(fh):
+                if i >= PREVIEW_LINES:
+                    break
+                lines.append(line.rstrip("\n\r"))
+            truncated = bool(fh.readline())
+    except OSError as e:
+        return [f"(cannot read: {e})"], "err", True
+    if not lines:
+        return ["(empty file)"], "", True
+    return lines, "", truncated
+
+
+def format_mtime(ts: float) -> str:
+    """Format a timestamp as a short local date-time string."""
+    try:
+        return time.strftime("%Y-%m-%d %H:%M", time.localtime(ts))
+    except (OverflowError, OSError, ValueError):
+        return "?"
+
+
+def total_lines(path: Path) -> int:
+    """Count lines in a (text) file; returns -1 on error."""
+    try:
+        with path.open("rb") as fh:
+            return sum(1 for _ in fh)
+    except OSError:
+        return -1
+
+
+# ---------- markdown rendering for the preview ------------------------------
+
+
+def _md_inline(text: str) -> str:
+    """Render inline markdown (bold/italic/code/links) as plain text.
+
+    Bold becomes *text*, italic /text/, code 'code', links text (url).
+    Placeholder control characters are used while rewriting so the rules
+    cannot chew on each other's markers; they are resolved at the end.
+    """
+    # Inline code first, protected from all other rules.
+    text = re.sub(r"`([^`]+)`", "\x02\\1\x02", text)
+    # Images ![alt](url) -> alt (url); do before links (pattern overlap).
+    text = re.sub(r"!\[([^\]]*)\]\(([^)\s]+)\)", r"\1 (\2)", text)
+    # Links [text](url) -> text (url)
+    text = re.sub(
+        r"\[([^\]]+)\]\(([^)\s]+)\)", r"\1 (\2)", text
+    )
+    # Bold **text** / __text__ -> *text* (placeholder, resolved below)
+    text = re.sub(r"\*\*(.+?)\*\*", "\x01\\1\x01", text)
+    text = re.sub(r"__(.+?)__", "\x01\\1\x01", text)
+    # Italic *text* / _text_ -> /text/
+    text = re.sub(r"(?<![\w*])\*(?![\s*])(.+?)(?<![\s*])\*(?![\w])", "\x03\\1\x03", text)
+    text = re.sub(r"(?<![\w_])_(?![\s_])(.+?)(?<![\s_])_(?![\w])", "\x03\\1\x03", text)
+    # Strikethrough ~~text~~ -> -text-
+    text = re.sub(r"~~(.+?)~~", r"-\1-", text)
+    # Resolve placeholders: bold '*', italic '/', code "'".
+    return text.replace("\x01", "*").replace("\x03", "/").replace("\x02", "'")
+
+
+def _wrap(text: str, width: int) -> list[str]:
+    """Word-wrap a plain text line to width (>=1). Never returns []."""
+    width = max(1, width)
+    if len(text) <= width:
+        return [text]
+    out = []
+    rest = text
+    while len(rest) > width:
+        cut = rest.rfind(" ", 0, width + 1)
+        if cut <= 0:
+            cut = width
+        out.append(rest[:cut])
+        rest = rest[cut:].lstrip()
+    out.append(rest)
+    return out
+
+
+def render_markdown(
+    lines: list[str], width: int
+) -> tuple[list[str], list[int]]:
+    """Very small Markdown-to-plain-text renderer for the preview pane.
+
+    Supports: ATX headings (# .. ######), fenced code blocks (``` or ~~~),
+    bullet/numbered lists (with simple wrapping), block quotes (>),
+    horizontal rules (---), and inline styles (bold, italic, code, links).
+
+    Returns (out_lines, out_attrs) where out_attrs[i] is the curses attribute
+    (an int) to use for out_lines[i]. Callers without colors can ignore it
+    (values degrade to plain A_NORMAL / A_BOLD / A_REVERSE).
+    """
+    out: list[str] = []
+    attrs: list[int] = []
+    width = max(4, width)
+
+    heading_attrs = {
+        1: curses.A_BOLD | curses.A_UNDERLINE,
+        2: curses.A_BOLD | curses.A_UNDERLINE,
+        3: curses.A_BOLD,
+    }
+
+    def emit(text: str, attr: int = curses.A_NORMAL) -> None:
+        if not text:
+            out.append("")
+            attrs.append(attr)
+            return
+        for piece in _wrap(text, width):
+            out.append(piece[:width])
+            attrs.append(attr)
+
+    in_code = False
+    code_marker = ""
+    prev_blank = True
+    for raw in lines:
+        line = raw.rstrip("\n")
+
+        # Fenced code blocks
+        stripped = line.lstrip()
+        if in_code:
+            if stripped.startswith(code_marker):
+                in_code = False
+                emit("")
+                prev_blank = True
+            else:
+                for piece in _wrap(stripped, width):
+                    out.append("    " + piece[: max(1, width - 4)])
+                    attrs.append(curses.A_NORMAL)
+            continue
+        if stripped.startswith("```") or stripped.startswith("~~~"):
+            in_code = True
+            code_marker = stripped[:3]
+            emit("")
+            prev_blank = True
+            continue
+
+        # Horizontal rule
+        if re.fullmatch(r"\s*(\*\s*){3,}(-\s*){3,}(_\s*){3,}", line):
+            emit("")
+            emit("-" * width, curses.A_DIM)
+            prev_blank = False
+            continue
+
+        # Headings
+        m = re.match(r"(#{1,6})\s+(.*?)\s*#*\s*$", line)
+        if m:
+            level = len(m.group(1))
+            text = _md_inline(m.group(2))
+            emit("")
+            if level <= 2:
+                attr = heading_attrs[level]
+                emit(text, attr)
+                emit("=" * min(width, max(4, len(text))), curses.A_DIM)
+            else:
+                emit(text, heading_attrs.get(3, curses.A_BOLD))
+            prev_blank = False
+            continue
+
+        # Block quotes (single-level, consecutive > lines merged)
+        if stripped.startswith(">"):
+            content = stripped.lstrip("> ")
+            emit("│ " + _md_inline(content), curses.A_BOLD)
+            prev_blank = False
+            continue
+
+        # Lists
+        lm = re.match(r"(\s*)([-*+]|\d+[.)])\s+(.*)$", line)
+        if lm:
+            indent = len(lm.group(1)) // 2
+            marker = lm.group(2)
+            if marker in "-*+":
+                bullet = "• "
+            else:
+                bullet = marker.split(".")[0].split(")")[0] + ". "
+            prefix = "  " * indent + bullet
+            body = _md_inline(lm.group(3))
+            first = True
+            for piece in _wrap(prefix + body, max(4, width - indent * 2)):
+                if first:
+                    emit(piece, curses.A_BOLD if bullet.strip() == "•" else curses.A_NORMAL)
+                    first = False
+                else:
+                    emit("  " * indent + "  " + piece)
+            prev_blank = False
+            continue
+
+        # Blank line
+        if not stripped:
+            if not prev_blank:
+                emit("")
+            prev_blank = True
+            continue
+
+        # Paragraph text
+        emit(_md_inline(stripped))
+        prev_blank = False
+
+    while out and out[-1] == "":
+        out.pop()
+        attrs.pop()
+    return out, attrs
+
+
 # ---------- input ------------------------------------------------------------
 
 def prompt_line(
@@ -160,16 +469,18 @@ def prompt_line(
     # Keep keypad ON so arrow keys arrive as KEY_* constants instead of an
     # ESC prefix that would otherwise be mis-read as "user pressed cancel".
     try:
-        stdscr.addstr(row, 0, prompt)
+        stdscr.addstr(row, 0, prompt + initial)
         stdscr.clrtoeol()
         stdscr.refresh()
 
         buf = initial
         while True:
             ch = stdscr.get_wch()
-            if ch in (27, -1):  # bare ESC (get_wch reports -1 for ESC)
+            # get_wch returns ints for special keys but plain strings for
+            # ordinary characters - including "\n", "\r" and "\x1b".
+            if ch in ("\x1b", 27, -1):  # bare ESC
                 return None
-            if ch in (10, 13, curses.KEY_ENTER):
+            if ch in ("\n", "\r", 10, 13, curses.KEY_ENTER):
                 break
             if ch in (curses.KEY_BACKSPACE, 127, 8) or ch in ("\x7f", "\x08"):
                 if buf:
@@ -198,11 +509,15 @@ def prompt_line(
 
 
 def confirm(stdscr: curses.window, prompt: str) -> bool:
-    """Ask a yes/no question via prompt_line. True only on explicit y/yes."""
+    """Ask a yes/no question via prompt_line. True only on explicit y/yes.
+
+    The buffer is prefilled with "n", so a typed "y" lands after it ("ny");
+    we therefore look for a "y" anywhere instead of checking the first char.
+    """
     answer = prompt_line(stdscr, prompt, initial="n")
     if answer is None:
         return False
-    return answer.strip().lower().startswith("y")
+    return "y" in answer.strip().lower()
 
 
 # ---------- rendering -------------------------------------------------------
@@ -246,15 +561,37 @@ def draw(
     show_hidden: bool,
     query: str | None,
     colors: dict[str, int],
+    split: bool = False,
+    preview_top: int = 0,
+    info_suffix: str = "",
+    ordered: bool = False,
+    sort_mode: str = "name",
+    copy_source: Path | None = None,
+    move_source: Path | None = None,
+    preview_top_box: list[int] | None = None,
 ) -> int:
     stdscr.erase()
     max_y, max_x = stdscr.getmaxyx()
 
     visible = filtered if filtered is not None else entries
 
+    # Split layout: leave the right half of the screen for the preview pane.
+    list_width = max_x
+    preview_lines: list[str] | None = None
+    preview_attrs: list[int] = []
+    preview_title = ""
+    preview_width = 0
+    preview_x = max_x
+    if split and max_x >= 40:
+        preview_x = max_x // 2 + 1
+        preview_width = max_x - preview_x
+        list_width = preview_x - 1
+
     # Header
     hidden_flag = "  (hidden shown)" if show_hidden else ""
-    header = f" {cwd}{hidden_flag} "
+    sort_flag = f"  [sort: {sort_mode}]" if ordered else ""
+    flags = hidden_flag + sort_flag
+    header = f" {cwd}{flags} "
     if colors:
         stdscr.attron(curses.color_pair(colors["header"]) | curses.A_BOLD)
     try:
@@ -264,6 +601,15 @@ def draw(
     if colors:
         stdscr.attroff(curses.color_pair(colors["header"]) | curses.A_BOLD)
 
+    # Right side of the header: entry counts (dirs/files).
+    try:
+        n_dirs = sum(1 for e in visible if not is_parent(e) and e.is_dir(follow_symlinks=True))
+        n_files = len(visible) - n_dirs - (1 if any(is_parent(e) for e in visible) else 0)
+        counts = f"{n_dirs} dir(s), {n_files} file(s) "
+        stdscr.addnstr(0, max(0, max_x - len(counts) - 1), counts, max_x - 1, curses.A_DIM)
+    except curses.error:
+        pass
+
     # List area
     list_top = 1
     list_bottom = max_y - 2  # leave one row for status, one for footer
@@ -297,7 +643,9 @@ def draw(
             is_dir = entry.is_dir(follow_symlinks=True)
             full = entry
 
-        label = format_entry(name, is_dir, full, max_x - 1)
+        label = format_entry(name, is_dir, full, list_width - 1)
+        if info_suffix and entry_i == selected:
+            label = (label.rstrip() + "  " + info_suffix)[: list_width - 1].ljust(list_width - 1)
 
         attr = curses.A_NORMAL
         if colors:
@@ -318,7 +666,7 @@ def draw(
         line_y = list_top + (entry_i - start)
         if line_y < list_bottom:
             try:
-                stdscr.addnstr(line_y, 0, label, max_x - 1, attr)
+                stdscr.addnstr(line_y, 0, label, list_width - 1, attr)
             except curses.error:
                 pass
 
@@ -338,17 +686,265 @@ def draw(
     except curses.error:
         pass
 
-    # Footer (key hints)
+    # Footer (key hints) - always ends with the quit hint.
-    footer = " Up/Dn move | Enter open | / live-search | r rename | d delete | n new dir | c copy | x move | p paste | . hidden | q quit "
+    base_footer = " Up/Dn move | Enter open | v preview | / search | r rename | d delete | n new dir | t new file | c copy | x move | p paste | s sort | . hidden | ~ home | q quit "
+    if split:
+        base_footer = " j/k scroll preview | Enter view file | f view | v close | g/G top/bottom | q quit "
+    mark = ""
+    if move_source is not None:
+        mark = f" [MOVE: {move_source.name}]"
+    elif copy_source is not None:
+        mark = f" [COPY: {copy_source.name}]"
+    footer = (base_footer + mark)[-max_x:]
     try:
         stdscr.addnstr(max_y - 1, 0, footer, max_x - 1, curses.A_DIM)
     except curses.error:
         pass
 
+    # Preview pane is drawn last so it can overlay the (cleared) right half.
+    if split and max_x >= 40 and preview_lines is None and visible:
+        entry = visible[selected]
+        preview_lines, preview_attrs, preview_title = build_preview(
+            entry, cwd, preview_width
+        )
+    if preview_lines is not None:
+        new_top = draw_preview(
+            stdscr,
+            preview_lines,
+            preview_attrs,
+            preview_title,
+            preview_top,
+            preview_x,
+            preview_width,
+            rows,
+            colors,
+        )
+        if preview_top_box is not None:
+            preview_top_box[0] = new_top
+
     stdscr.refresh()
     return selected
 
 
+# ---------- preview ----------------------------------------------------------
+
+
+def build_preview(
+    entry: Path, cwd: Path, width: int
+) -> tuple[list[str], list[int], str]:
+    """Build the preview content for an entry.
+
+    Returns (lines, attrs, title). `lines`/`attrs` are parallel lists as in
+    render_markdown; title is shown at the top of the preview pane.
+    """
+    if is_parent(entry):
+        target = cwd.parent
+    else:
+        target = entry
+
+    try:
+        is_dir = target.is_dir(follow_symlinks=True)
+    except OSError:
+        is_dir = False
+
+    if is_dir:
+        lines: list[str] = []
+        attrs: list[int] = []
+        try:
+            st = target.stat()
+            lines.append(f"Folder: {target.name or str(target)}")
+            attrs.append(curses.A_BOLD)
+            lines.append("")
+            attrs.append(0)
+            sub = sorted(target.iterdir(), key=lambda p: p.name.lower())
+            dirs = [p for p in sub if p.is_dir(follow_symlinks=True)]
+            files = [p for p in sub if not p.is_dir(follow_symlinks=True)]
+            lines.append(f"{len(dirs)} folders, {len(files)} files")
+            attrs.append(0)
+            lines.append("")
+            attrs.append(0)
+            for p in (dirs + files)[:PREVIEW_LINES]:
+                try:
+                    pst = p.stat()
+                    size = human_size(pst.st_size)
+                    mtime = format_mtime(pst.st_mtime)
+                except OSError:
+                    size, mtime = "?", "?"
+                kind = "D" if p.is_dir(follow_symlinks=True) else "F"
+                name_w = max(1, width - 24)
+                lines.append(
+                    f" {kind} {p.name[:name_w]:<{name_w}} {size:>7}  {mtime}"
+                )
+                attrs.append(0)
+            shown = min(len(sub), PREVIEW_LINES)
+            if len(sub) > shown:
+                lines.append(f" ... and {len(sub) - shown} more")
+                attrs.append(curses.A_DIM)
+        except OSError as e:
+            lines.append(f"(cannot read folder: {e})")
+            attrs.append(0)
+        return lines, attrs, f"Folder: {target.name or str(target)}"
+
+    if not target.is_file(follow_symlinks=True):
+        return (["(not a regular file)"], [0], target.name)
+
+    if is_text_file(target):
+        raw, err, truncated = read_preview_lines(target)
+        if err:
+            return raw, [0] * len(raw), target.name
+        if target.suffix.lower() in (".md", ".markdown"):
+            body, body_attrs = render_markdown(raw, max(4, width - 2))
+            title = f"Markdown: {target.name}"
+        else:
+            body = [line[:width] for line in raw]
+            body_attrs = [0] * len(body)
+            title = target.name
+        try:
+            st = target.stat()
+            head = (
+                f"{human_size(st.st_size)}  {format_mtime(st.st_mtime)}  "
+                f"first {len(raw)} of {total_lines(target)} lines"
+            )
+        except OSError:
+            head = f"first {len(raw)} lines"
+        if truncated:
+            head += "  (truncated)"
+        lines = [head, ""] + body
+        attrs = [curses.A_DIM, 0] + body_attrs
+        return lines, attrs, title
+
+    return (["(binary file - no preview)"], [0], target.name)
+
+
+def draw_preview(
+    stdscr: curses.window,
+    lines: list[str],
+    attrs: list[int],
+    title: str,
+    top: int,
+    x: int,
+    width: int,
+    height: int,
+    colors: dict[str, int],
+) -> int:
+    """Draw the preview pane at (x, 1) with the given size. Returns new top."""
+    if width < 3 or height < 1:
+        return top
+    top = max(0, min(top, max(0, len(lines) - 1)))
+    border_attr = curses.A_DIM
+    if colors and "header" in colors:
+        border_attr = curses.color_pair(colors["header"])
+
+    # Title row
+    title_text = f" {title} "[: width - 1]
+    try:
+        stdscr.addnstr(0, x, title_text, width - 1, border_attr | curses.A_BOLD)
+        stdscr.addnstr(0, x + len(title_text), "─" * (width - len(title_text) - 1), width - 1 - len(title_text), border_attr)
+    except curses.error:
+        pass
+
+    for row in range(height):
+        idx = top + row
+        if idx >= len(lines):
+            break
+        text = lines[idx][: width - 2]
+        attr = attrs[idx] if idx < len(attrs) else curses.A_NORMAL
+        if attr == 0:
+            attr = curses.A_NORMAL
+        try:
+            stdscr.addnstr(1 + row, x, text, width - 2, attr)
+        except curses.error:
+            pass
+
+    # Scroll indicator
+    if len(lines) > height:
+        frac = top / max(1, len(lines) - height)
+        pos = min(height - 1, int(frac * (height - 1)))
+        try:
+            stdscr.addch(1 + pos, x + width - 1, "█", border_attr)
+        except curses.error:
+            pass
+    return top
+
+
+def view_file_fullscreen(
+    stdscr: curses.window, filepath: Path, colors: dict[str, int]
+) -> str:
+    """Full-screen text viewer for a file (Enter on it in preview mode, or f).
+
+    Returns a short status string. Supports Markdown rendering (toggle with m).
+    """
+    raw, err, _trunc = read_preview_lines(filepath)
+    if err:
+        return err
+    is_md = filepath.suffix.lower() in (".md", ".markdown")
+
+    def content(max_y: int, max_x: int, rendered: bool) -> tuple[list[str], list[int]]:
+        if rendered and is_md:
+            return render_markdown(raw, max(4, max_x - 2))
+        return [line[: max(1, max_x - 1)] for line in raw], [0] * len(raw)
+
+    top = 0
+    rendered = is_md  # default to rendered for Markdown
+    while True:
+        stdscr.erase()
+        max_y, max_x = stdscr.getmaxyx()
+        lines, attrs = content(max_y - 2, max_x, rendered)
+        top = max(0, min(top, max(0, len(lines) - 1)))
+        title = f" {filepath.name} "
+        if is_md:
+            title += "[m: raw]" if rendered else "[m: rendered]"
+        title += " [q: back]"
+        tattr = curses.A_BOLD | (curses.color_pair(colors["header"]) if colors else 0)
+        try:
+            stdscr.addnstr(0, 0, title[: max_x - 1], max_x - 1, tattr)
+        except curses.error:
+            pass
+        for row in range(max_y - 2):
+            idx = top + row
+            if idx >= len(lines):
+                break
+            attr = attrs[idx] if idx < len(attrs) else 0
+            if attr == 0:
+                attr = curses.A_NORMAL
+            try:
+                stdscr.addnstr(1 + row, 0, lines[idx], max_x - 1, attr)
+            except curses.error:
+                pass
+        try:
+            stdscr.addnstr(
+                max_y - 1, 0,
+                f" {len(raw)} lines | j/k or arrows scroll | m toggle rendering | q back ",
+                max_x - 1, curses.A_DIM,
+            )
+        except curses.error:
+            pass
+        stdscr.refresh()
+
+        ch = stdscr.getch()
+        page = max(1, (max_y - 3))
+        if ch in (ord("q"), 27):
+            break
+        elif ch in (curses.KEY_UP, ord("k")):
+            top = max(0, top - 1)
+        elif ch in (curses.KEY_DOWN, ord("j")):
+            top = min(max(0, len(lines) - 1), top + 1)
+        elif ch in (curses.KEY_PPAGE, curses.KEY_BACKSPACE, 127, 8):
+            top = max(0, top - page)
+        elif ch in (curses.KEY_NPAGE, ord(" ")):
+            top = min(max(0, len(lines) - 1), top + page)
+        elif ch in (curses.KEY_HOME, ord("g")):
+            top = 0
+        elif ch in (curses.KEY_END, ord("G")):
+            top = max(0, len(lines) - 1)
+        elif ch in (ord("m"), ord("M")):
+            if is_md:
+                rendered = not rendered
+        elif ch == curses.KEY_RESIZE:
+            continue
+    return ""
+
+
 # ---------- file type / open-with configuration -----------------------------
 
 OPEN_COMMANDS = {
@@ -558,6 +1154,12 @@ def main(stdscr: curses.window) -> None:
     filtered = None  # when not None, used for display (search active)
     copy_source: Path | None = None
     move_source: Path | None = None
+    preview = False          # split screen with preview pane on/off
+    preview_top = 0          # scroll offset inside the preview pane
+    preview_top_box = [0]    # draw() clamps it back through this
+    preview_sel_at_reset = 0  # selection the preview scroll was last reset for
+    sort_mode = "name"       # current sort order
+    dir_cursors: dict[str, int] = {}  # remember cursor per directory
 
     while True:
         try:
@@ -582,6 +1184,32 @@ def main(stdscr: curses.window) -> None:
                             ]
                         filtered = candidates
 
+            # Sort (only the real entries; '..' stays on top).
+            if filtered is None and sort_mode != "name":
+                real = [e for e in entries if not is_parent(e)]
+                parent_only = [e for e in entries if is_parent(e)]
+                entries = parent_only + sort_entries(real, sort_mode)
+
+            # Info for the selected entry, shown at the end of its row.
+            vis_now = filtered if filtered is not None else entries
+            info_suffix = ""
+            if vis_now:
+                sel_entry = vis_now[max(0, min(selected, len(vis_now) - 1))]
+                if not is_parent(sel_entry):
+                    try:
+                        st = sel_entry.stat()
+                        info_suffix = (
+                            f"{human_size(st.st_size)}  {format_mtime(st.st_mtime)}"
+                        )
+                    except OSError:
+                        pass
+
+            # Scroll the preview back to its top when the selection changed.
+            if preview and selected != preview_sel_at_reset:
+                preview_top = 0
+                preview_top_box[0] = 0
+                preview_sel_at_reset = selected
+
             selected = draw(
                 stdscr,
                 entries,
@@ -593,6 +1221,14 @@ def main(stdscr: curses.window) -> None:
                 show_hidden,
                 query,
                 colors,
+                split=preview,
+                preview_top=preview_top,
+                preview_top_box=preview_top_box,
+                info_suffix=info_suffix,
+                ordered=sort_mode != "name",
+                sort_mode=sort_mode,
+                copy_source=copy_source,
+                move_source=move_source,
             )
 
             status = ""
@@ -603,6 +1239,10 @@ def main(stdscr: curses.window) -> None:
             if ch in (ord("q"),):
                 break
 
+            if ch == 12:  # Ctrl+L: force a full redraw
+                stdscr.clear()
+                continue
+
             if ch in (curses.KEY_UP, ord("k")):
                 vis = filtered if filtered is not None else entries
                 if vis:
@@ -613,14 +1253,74 @@ def main(stdscr: curses.window) -> None:
                 if vis:
                     selected = (selected + 1) % len(vis)
 
+            elif ch in (ord("K"),) and preview:
+                preview_top = max(0, preview_top_box[0] - 1)
+
+            elif ch in (ord("J"),) and preview:
+                preview_top = min(
+                    max(0, preview_top_box[0] + 1), preview_top_box[0] + 1
+                )
+
+            elif ch == ord("g"):
+                selected = 0
+
+            elif ch == ord("G"):
+                vis = filtered if filtered is not None else entries
+                if vis:
+                    selected = len(vis) - 1
+
+            elif ch == curses.KEY_PPAGE:
+                max_y, _mx = stdscr.getmaxyx()
+                page = max(1, (max_y - 3))
+                selected = max(0, selected - page)
+
+            elif ch == curses.KEY_NPAGE:
+                max_y, _mx = stdscr.getmaxyx()
+                vis = filtered if filtered is not None else entries
+                page = max(1, (max_y - 3))
+                if vis:
+                    selected = min(len(vis) - 1, selected + page)
+
+            elif ch == ord("~"):
+                try:
+                    home = Path.home()
+                except RuntimeError:
+                    home = None
+                if home is None or not home.is_dir():
+                    status = "Cannot determine home directory"
+                    status_kind = "status_err"
+                elif home == cwd:
+                    status = "Already in home directory"
+                    status_kind = "status_ok"
+                else:
+                    try:
+                        os.chdir(home)
+                        dir_cursors[str(cwd)] = selected
+                        cwd = Path.cwd()
+                        selected = dir_cursors.get(str(cwd), 0)
+                        filtered = None
+                        query = None
+                        preview = False
+                    except OSError as e:
+                        status = f"Cannot enter home: {e}"
+                        status_kind = "status_err"
+
+            elif ch == ord("s"):
+                idx = SORT_MODES.index(sort_mode)
+                sort_mode = SORT_MODES[(idx + 1) % len(SORT_MODES)]
+                status = f"Sort: {sort_mode}"
+                status_kind = "status_ok"
+
             elif ch in (curses.KEY_BACKSPACE, 127, 8, ord("h")):
                 # Parent directory
                 if cwd != cwd.parent:
+                    dir_cursors[str(cwd)] = selected
                     cwd = cwd.parent
                     os.chdir(cwd)
-                    selected = 0
+                    selected = dir_cursors.get(str(cwd), 0)
                     filtered = None
                     query = None
+                    preview = False
                 else:
                     status = "Already at filesystem root"
                     status_kind = "status_err"
@@ -632,18 +1332,22 @@ def main(stdscr: curses.window) -> None:
                 entry = vis[selected]
                 if is_parent(entry):
                     if cwd != cwd.parent:
+                        dir_cursors[str(cwd)] = selected
                         cwd = cwd.parent
                         os.chdir(cwd)
-                        selected = 0
+                        selected = dir_cursors.get(str(cwd), 0)
                         filtered = None
                         query = None
+                        preview = False
                 elif entry.is_dir(follow_symlinks=True):
                     try:
+                        dir_cursors[str(cwd)] = selected
                         os.chdir(entry)
                         cwd = Path.cwd()
-                        selected = 0
+                        selected = dir_cursors.get(str(cwd), 0)
                         filtered = None
                         query = None
+                        preview = False
                     except PermissionError:
                         status = f"Permission denied: {entry.name}"
                         status_kind = "status_err"
@@ -652,6 +1356,19 @@ def main(stdscr: curses.window) -> None:
                         status_kind = "status_err"
                 else:
                     if entry.is_file(follow_symlinks=True):
+                        if preview:
+                            # In preview mode Enter opens the built-in viewer.
+                            if is_text_file(entry):
+                                msg = view_file_fullscreen(stdscr, entry, colors)
+                                if msg:
+                                    status = msg
+                                    status_kind = "status_err"
+                            else:
+                                argv = file_menu(stdscr, entry, colors)
+                                if argv is not None:
+                                    status = run_external(stdscr, argv)
+                                    status_kind = "status_ok" if status.startswith("Ran:") else "status_err"
+                        else:
                             argv = file_menu(stdscr, entry, colors)
                             if argv is not None:
                                 status = run_external(stdscr, argv)
@@ -703,6 +1420,48 @@ def main(stdscr: curses.window) -> None:
                             ]
                         filtered = candidates if candidates else []
 
+            elif ch in (ord("v"), ord("V"), 9):  # 9 = Tab
+                preview = not preview
+                if preview:
+                    preview_top = 0
+                    preview_top_box[0] = 0
+                    preview_sel_at_reset = selected
+
+            elif ch in (ord("f"), ord("F")):
+                vis = filtered if filtered is not None else entries
+                if not vis:
+                    continue
+                entry = vis[selected]
+                if is_parent(entry):
+                    status = "No file selected"
+                    status_kind = "status_err"
+                elif entry.is_file(follow_symlinks=True) and is_text_file(entry):
+                    msg = view_file_fullscreen(stdscr, entry, colors)
+                    if msg:
+                        status = msg
+                        status_kind = "status_err"
+                else:
+                    status = "Not a previewable text file"
+                    status_kind = "status_err"
+
+            elif ch == ord("t") or ch == ord("T"):
+                name = prompt_line(stdscr, "New file name: ")
+                if name is None:
+                    continue
+                name = name.strip()
+                if not name:
+                    continue
+                try:
+                    target = cwd / name
+                    if target.exists():
+                        raise FileExistsError(f"'{name}' already exists")
+                    target.touch()
+                    status = f"Created '{name}'"
+                    status_kind = "status_ok"
+                except OSError as e:
+                    status = f"Create failed: {e}"
+                    status_kind = "status_err"
+
             elif ch == ord("."):
                 show_hidden = not show_hidden
                 selected = 0