security: slug validation, path traversal protection, temp file cleanup

- SlugGuard.IsValid() rejects slugs with path traversal (../, //, uppercase)
- SlugGuard.ToSafePath() ensures sync writes stay within target directory
- PushCommand: skip files with invalid slugs before upload
- SyncCommand: validate server-returned slugs before writing to disk
- EditCommand/NewCommand: try/finally guarantees temp file deletion on crash
- NotesCache: set 600 permissions on cache file (metadata only, no token)
- NewCommand: remove dead Sha256 method (HashHelper already covers this)

NozCli/Commands/EditCommand.cs

@@ -28,22 +28,30 @@ public class EditCommand : ICommand
         var tmp = Path.Combine(Path.GetTempPath(), $"noz-{slug.Replace('/', '-')}.md");
         await File.WriteAllTextAsync(tmp, note.Markdown);
 
-        var (editor, editorArgs) = useCode
-            ? ResolveCode(tmp, ctx.Config.CodeEditor)
-            : ResolveTerminal(tmp, ctx.Config.Editor);
-
-        AnsiConsole.MarkupLine($"[dim]Opening {editor} …[/]");
-        var proc = Process.Start(new ProcessStartInfo
+        string edited;
+        try
         {
-            FileName        = editor,
-            Arguments       = editorArgs,
-            UseShellExecute = false,
-        });
-        proc?.WaitForExit();
+            var (editor, editorArgs) = useCode
+                ? ResolveCode(tmp, ctx.Config.CodeEditor)
+                : ResolveTerminal(tmp, ctx.Config.Editor);
+
+            AnsiConsole.MarkupLine($"[dim]Opening {editor} …[/]");
+            var proc = Process.Start(new ProcessStartInfo
+            {
+                FileName        = editor,
+                Arguments       = editorArgs,
+                UseShellExecute = false,
+            });
+            proc?.WaitForExit();
+
+            edited = await File.ReadAllTextAsync(tmp);
+        }
+        finally
+        {
+            if (File.Exists(tmp)) File.Delete(tmp);
+        }
 
-        var edited  = await File.ReadAllTextAsync(tmp);
         var newHash = Sha256(edited);
-        File.Delete(tmp);
 
         if (newHash == note.Hash)
         {

NozCli/Commands/NewCommand.cs

@@ -1,6 +1,4 @@
 using System.Diagnostics;
-using System.Security.Cryptography;
-using System.Text;
 using NozCli.Core.Models;
 using NozCli.Repl;
 using Spectre.Console;
@@ -47,21 +45,28 @@ public class NewCommand : ICommand
         var tmp = Path.Combine(Path.GetTempPath(), $"noz-new-{slug.Replace('/', '-')}.md");
         await File.WriteAllTextAsync(tmp, template);
 
-        var (editor, editorArgs) = useCode
-            ? EditCommand.ResolveCode(tmp, ctx.Config.CodeEditor)
-            : EditCommand.ResolveTerminal(tmp, ctx.Config.Editor);
-
-        AnsiConsole.MarkupLine($"[dim]Opening {editor} …[/]");
-        var proc = Process.Start(new ProcessStartInfo
+        string markdown;
+        try
         {
-            FileName        = editor,
-            Arguments       = editorArgs,
-            UseShellExecute = false,
-        });
-        proc?.WaitForExit();
+            var (editor, editorArgs) = useCode
+                ? EditCommand.ResolveCode(tmp, ctx.Config.CodeEditor)
+                : EditCommand.ResolveTerminal(tmp, ctx.Config.Editor);
 
-        var markdown = await File.ReadAllTextAsync(tmp);
-        File.Delete(tmp);
+            AnsiConsole.MarkupLine($"[dim]Opening {editor} …[/]");
+            var proc = Process.Start(new ProcessStartInfo
+            {
+                FileName        = editor,
+                Arguments       = editorArgs,
+                UseShellExecute = false,
+            });
+            proc?.WaitForExit();
+
+            markdown = await File.ReadAllTextAsync(tmp);
+        }
+        finally
+        {
+            if (File.Exists(tmp)) File.Delete(tmp);
+        }
 
         if (markdown.Trim() == template.Trim())
         {
@@ -85,6 +90,4 @@ public class NewCommand : ICommand
         string.Join(' ', slug.Split('-').Select(w =>
             w.Length > 0 ? char.ToUpper(w[0]) + w[1..] : w));
 
-    private static string Sha256(string text) =>
-        Convert.ToHexString(SHA256.HashData(Encoding.UTF8.GetBytes(text))).ToLower();
 }

NozCli/Commands/PushCommand.cs

@@ -1,4 +1,5 @@
 using NozCli.Repl;
+using NozCli.Security;
 using Spectre.Console;
 
 namespace NozCli.Commands;
@@ -54,6 +55,13 @@ public class PushCommand : ICommand
                     var relative = Path.GetRelativePath(localPath, file);
                     var slug     = relative.Replace(Path.DirectorySeparatorChar, '/').Replace(".md", "");
 
+                    if (!SlugGuard.IsValid(slug))
+                    {
+                        AnsiConsole.MarkupLine($"[yellow]⚠ Skipped invalid slug:[/] {slug}");
+                        task.Increment(1);
+                        continue;
+                    }
+
                     var markdown = await File.ReadAllTextAsync(file);
                     var localHash = NozCli.Core.Client.HashHelper.Sha256(markdown);
 

NozCli/Commands/SyncCommand.cs

@@ -1,6 +1,7 @@
 using NozCli.Core.Client;
 using NozCli.Core.Models;
 using NozCli.Repl;
+using NozCli.Security;
 using Spectre.Console;
 
 namespace NozCli.Commands;
@@ -51,7 +52,13 @@ public class SyncCommand : ICommand
 
         foreach (var note in noteList)
         {
-            var filePath = SlugToPath(localPath, note.Slug);
+            if (!SlugGuard.IsValid(note.Slug))
+            {
+                AnsiConsole.MarkupLine($"[yellow]⚠ Skipped unsafe slug from server:[/] {note.Slug}");
+                continue;
+            }
+
+            var filePath = SlugGuard.ToSafePath(localPath, note.Slug);
 
             if (!force && note.Hash is not null && File.Exists(filePath))
             {
@@ -104,7 +111,7 @@ public class SyncCommand : ICommand
                         try
                         {
                             var content  = await ctx.Api.GetNoteAsync(note.Slug, innerCt);
-                            var filePath = SlugToPath(localPath, note.Slug);
+                            var filePath = SlugGuard.ToSafePath(localPath, note.Slug)!;
 
                             Directory.CreateDirectory(Path.GetDirectoryName(filePath)!);
                             await File.WriteAllTextAsync(filePath, content.Markdown, innerCt);
@@ -136,6 +143,4 @@ public class SyncCommand : ICommand
         }
     }
 
-    private static string SlugToPath(string baseDir, string slug) =>
-        Path.Combine(baseDir, slug.Replace('/', Path.DirectorySeparatorChar) + ".md");
 }

NozCli/Rendering/MarkdownRenderer.cs

@@ -0,0 +1,195 @@
+using System.Text;
+using System.Text.RegularExpressions;
+using Spectre.Console;
+
+namespace NozCli.Rendering;
+
+/// Terminal markdown renderer — converts common markdown to Spectre.Console output.
+/// Handles: headings, bold/italic, inline code, fenced code blocks,
+/// bullet/numbered lists, blockquotes, horizontal rules.
+public static partial class MarkdownRenderer
+{
+    public static void Render(string markdown)
+    {
+        var lines     = markdown.ReplaceLineEndings("\n").Split('\n');
+        var inCode    = false;
+        var codeLang  = "";
+        var codeBlock = new StringBuilder();
+
+        AnsiConsole.WriteLine();
+
+        for (var i = 0; i < lines.Length; i++)
+        {
+            var line = lines[i];
+
+            // ── Fenced code block ────────────────────────────────────────────
+            if (line.TrimStart().StartsWith("```"))
+            {
+                if (!inCode)
+                {
+                    inCode   = true;
+                    codeLang = line.TrimStart()[3..].Trim();
+                    codeBlock.Clear();
+                }
+                else
+                {
+                    inCode = false;
+                    RenderCodeBlock(codeBlock.ToString().TrimEnd(), codeLang);
+                }
+                continue;
+            }
+
+            if (inCode)
+            {
+                codeBlock.AppendLine(line);
+                continue;
+            }
+
+            // ── Horizontal rule ──────────────────────────────────────────────
+            if (HrRegex().IsMatch(line))
+            {
+                AnsiConsole.Write(new Rule() { Style = new Style(new Color(60, 60, 80)) });
+                continue;
+            }
+
+            // ── Headings ─────────────────────────────────────────────────────
+            if (line.StartsWith("### "))
+            {
+                AnsiConsole.MarkupLine($"\n  [bold white]{Markup.Escape(line[4..])}[/]");
+                continue;
+            }
+            if (line.StartsWith("## "))
+            {
+                AnsiConsole.MarkupLine($"\n[bold cyan]{Markup.Escape(line[3..])}[/]");
+                continue;
+            }
+            if (line.StartsWith("# "))
+            {
+                AnsiConsole.MarkupLine($"\n[bold underline cyan]{Markup.Escape(line[2..])}[/]\n");
+                continue;
+            }
+
+            // ── Blockquote ───────────────────────────────────────────────────
+            if (line.StartsWith("> "))
+            {
+                var content = ApplyInline(line[2..]);
+                AnsiConsole.MarkupLine($"[grey46]┃[/] [dim italic]{content}[/]");
+                continue;
+            }
+
+            // ── Bullet list ──────────────────────────────────────────────────
+            var bulletMatch = BulletRegex().Match(line);
+            if (bulletMatch.Success)
+            {
+                var indent  = bulletMatch.Groups[1].Value.Length / 2;
+                var content = ApplyInline(bulletMatch.Groups[2].Value);
+                var pad     = new string(' ', indent * 2);
+                AnsiConsole.MarkupLine($"{pad}  [dim cyan]•[/] {content}");
+                continue;
+            }
+
+            // ── Numbered list ────────────────────────────────────────────────
+            var numMatch = NumberedRegex().Match(line);
+            if (numMatch.Success)
+            {
+                var num     = numMatch.Groups[1].Value;
+                var content = ApplyInline(numMatch.Groups[2].Value);
+                AnsiConsole.MarkupLine($"  [dim cyan]{num}.[/] {content}");
+                continue;
+            }
+
+            // ── Empty line ───────────────────────────────────────────────────
+            if (string.IsNullOrWhiteSpace(line))
+            {
+                AnsiConsole.WriteLine();
+                continue;
+            }
+
+            // ── Paragraph ────────────────────────────────────────────────────
+            AnsiConsole.MarkupLine($"  {ApplyInline(line)}");
+        }
+
+        AnsiConsole.WriteLine();
+    }
+
+    // ── Code block rendering ─────────────────────────────────────────────────
+
+    private static void RenderCodeBlock(string code, string lang)
+    {
+        var header = lang.Length > 0 ? $"[dim]{Markup.Escape(lang)}[/]" : "[dim]code[/]";
+        var panel  = new Panel(new Text(code, new Style(new Color(200, 200, 220))))
+        {
+            Header      = new PanelHeader($" {header} "),
+            Border      = BoxBorder.Rounded,
+            BorderStyle = new Style(new Color(60, 60, 80)),
+            Padding     = new Padding(1, 0),
+        };
+        AnsiConsole.WriteLine();
+        AnsiConsole.Write(panel);
+    }
+
+    // ── Inline formatting ────────────────────────────────────────────────────
+
+    private static string ApplyInline(string raw)
+    {
+        // Collect all pattern matches, escape text between them.
+        // This ensures brackets/special chars in regular text don't break Spectre markup.
+        (Regex regex, Func<Match, string> format)[] patterns =
+        [
+            (InlineCodeRegex(), m => $"[bold cyan on grey7] {Markup.Escape(m.Groups[1].Value)} [/]"),
+            (BoldRegex(),       m => $"[bold]{Markup.Escape(m.Groups[1].Value)}[/]"),
+            (ItalicRegex(),     m => $"[italic]{Markup.Escape(m.Groups[1].Value)}[/]"),
+        ];
+
+        var spans = new List<(int start, int end, string replacement)>();
+
+        foreach (var (regex, format) in patterns)
+        {
+            foreach (Match m in regex.Matches(raw))
+            {
+                // Skip if overlapping with an already-claimed span
+                if (spans.Exists(s => m.Index < s.end && m.Index + m.Length > s.start))
+                    continue;
+                spans.Add((m.Index, m.Index + m.Length, format(m)));
+            }
+        }
+
+        spans.Sort((a, b) => a.start.CompareTo(b.start));
+
+        var sb = new StringBuilder();
+        var pos = 0;
+
+        foreach (var (start, end, replacement) in spans)
+        {
+            if (pos < start)
+                sb.Append(Markup.Escape(raw[pos..start]));
+            sb.Append(replacement);
+            pos = end;
+        }
+
+        if (pos < raw.Length)
+            sb.Append(Markup.Escape(raw[pos..]));
+
+        return sb.ToString();
+    }
+
+    // ── Compiled regexes (AOT-safe via [GeneratedRegex]) ────────────────────
+
+    [GeneratedRegex(@"^[-*_]{3,}\s*$")]
+    private static partial Regex HrRegex();
+
+    [GeneratedRegex(@"^( *)[-*+] (.+)$")]
+    private static partial Regex BulletRegex();
+
+    [GeneratedRegex(@"^(\d+)\. (.+)$")]
+    private static partial Regex NumberedRegex();
+
+    [GeneratedRegex(@"`([^`]+)`")]
+    private static partial Regex InlineCodeRegex();
+
+    [GeneratedRegex(@"\*\*([^*]+)\*\*")]
+    private static partial Regex BoldRegex();
+
+    [GeneratedRegex(@"(?<!\*)\*(?!\*)([^*]+)\*(?!\*)")]
+    private static partial Regex ItalicRegex();
+}

NozCli/Repl/NotesCache.cs

@@ -35,6 +35,9 @@ public static class NotesCache
             var tmp = CachePath + ".tmp";
             await File.WriteAllTextAsync(tmp, json);
             File.Move(tmp, CachePath, overwrite: true);
+
+            if (!OperatingSystem.IsWindows())
+                File.SetUnixFileMode(CachePath, UnixFileMode.UserRead | UnixFileMode.UserWrite);
         }
         catch { /* cache write failures are non-fatal */ }
     }

NozCli/Security/SlugGuard.cs

@@ -0,0 +1,34 @@
+using System.Text.RegularExpressions;
+
+namespace NozCli.Security;
+
+/// Validates slugs before they are sent to the server or written to disk.
+public static partial class SlugGuard
+{
+    // Valid slug: lowercase alphanumeric + hyphens, optionally separated by /
+    // Examples: "hydroponik", "biosysteme/hydroponik", "a/b/c"
+    [GeneratedRegex(@"^[a-z0-9][a-z0-9\-]*(?:/[a-z0-9][a-z0-9\-]*)*$")]
+    private static partial Regex ValidSlugRegex();
+
+    /// Returns true if the slug is safe to use (no path traversal, valid chars).
+    public static bool IsValid(string slug) =>
+        !string.IsNullOrWhiteSpace(slug) &&
+        !slug.Contains("..") &&
+        !slug.Contains("//") &&
+        ValidSlugRegex().IsMatch(slug);
+
+    /// Resolves a slug to a file path inside baseDir.
+    /// Returns null if the resulting path would escape baseDir (path traversal).
+    public static string? ToSafePath(string baseDir, string slug, string extension = ".md")
+    {
+        var rel      = slug.Replace('/', Path.DirectorySeparatorChar) + extension;
+        var fullPath = Path.GetFullPath(Path.Combine(baseDir, rel));
+        var baseFull = Path.GetFullPath(baseDir);
+
+        // Ensure the resolved path stays strictly inside baseDir
+        return fullPath.StartsWith(baseFull + Path.DirectorySeparatorChar,
+            StringComparison.OrdinalIgnoreCase)
+            ? fullPath
+            : null;
+    }
+}