fix: convert RTF to TXT through LibreOffice

src/Filee.Engines/Office/LibreOfficeConverter.cs

@@ -453,6 +453,10 @@ void Add(IEnumerable<string> sources, IEnumerable<string> targets, int cost)
         // turn into DOCX (Excel → DOCX → LibreOffice would cost 17 + 19).
         const int Chosen = 10;
         Add(Writer, [.. Writer, "txt", "html"], Fallback);
+        // RTF → TXT (#1204): the built-in routes read RTF through Pandoc, which makes a code span of every run in a
+        // monospace font (through Markdown, about 29) or loses the line breaks (through the HWPX writer, about 32).
+        // Direct only, so it stays the fallback as a step towards other formats.
+        edges.Add(new ConversionEdge("rtf", "txt", Chosen, DirectOnly: true));
         Add(Writer, ["pdf"], documents ? Chosen : Fallback);
         Add(Calc, [.. Calc, "html"], Fallback);
         Add(Calc, ["pdf"], sheets ? Chosen : Fallback);

tests/Filee.Engines.Tests/LibreOfficeFormatTests.cs

@@ -74,7 +74,9 @@ public void Every_edge_has_a_filter_of_its_application()
         }
         // Built-in engines stay first: LibreOffice's edges cost more than a normal direct conversion, except
         // presentations → PDF, which it lays out like PowerPoint (Settings → Engines, on by default).
-        Assert.All(LibreOffice.Edges.Where(e => !(impress.Contains(e.From) && e.To == "pdf")), e => Assert.True(e.Cost >= 25));
+        // RTF → TXT: RTF has no built-in reader, and every other route reads it through Pandoc (#1204).
+        Assert.All(LibreOffice.Edges.Where(e => !(impress.Contains(e.From) && e.To == "pdf") && !(e.From == "rtf" && e.To == "txt")),
+            e => Assert.True(e.Cost >= 25));
         foreach (var from in new[] { "dot", "wps", "wpd", "lwp", "abw", "pages", "sdw", "cwk", "mcw", "602", "psw", "fodt", "ott", "et", "numbers", "sdc", "fods", "ots", "xlt", "key", "dps", "sda", "fodp", "otp", "pub", "cdr", "cgm", "vsd", "odg", "fodg" })
             Assert.Contains(LibreOffice.Edges, e => e.From == from && e.To == "pdf");
         // Read-only formats are never targets.

tests/Filee.Engines.Tests/LibreOfficeRouteTests.cs

@@ -58,6 +58,17 @@ public void Word_and_excel_go_the_built_in_way_unless_libreoffice_is_chosen(stri
         Assert.Equal("libreoffice", Assert.Single(chosen.Plan(from, "pdf")!.Steps).Converter.Id);
     }
 
+    [Fact]
+    public void Rtf_goes_to_txt_through_libreoffice()
+    {
+        // Issue #1204: through Markdown, code copied from an IDE came out full of backticks.
+        var planner = Planner(slides: false, hwpToPdf: false);
+
+        Assert.Equal("libreoffice", Assert.Single(planner.Plan("rtf", "txt")!.Steps).Converter.Id);
+        Assert.Equal("pandoc", Assert.Single(planner.Plan("rtf", "md")!.Steps).Converter.Id);
+        Assert.DoesNotContain(planner.Plan("rtf", "epub")!.Steps, s => s.From == "rtf" && s.To == "txt"); // not a hop
+    }
+
     [Theory]
     [InlineData("docx")]
     [InlineData("txt")]

tests/Filee.Engines.Tests/RtfToTextTests.cs

@@ -0,0 +1,57 @@
+// RTF → TXT through LibreOffice (#1204): code copied from an IDE (a colour run per token and an italic run here and
+// there) keeps its text, its indentation and its blank lines. The route itself is in LibreOfficeRouteTests.
+
+using Filee.Core.Conversion;
+using Filee.Core.Presets;
+
+namespace Filee.Engines.Tests;
+
+public class RtfToTextTests(EngineFixture fx) : IClassFixture<EngineFixture>
+{
+    private const string IdeCode = """
+        {\rtf1\ansi\ansicpg1252\cocoartf2907
+        \cocoatextscaling0\cocoaplatform0{\fonttbl\f0\fmodern\fcharset0 Courier;\f1\fmodern\fcharset0 Courier-Oblique;}
+        {\colortbl;\red255\green255\blue255;\red195\green122\blue88;\red175\green177\blue183;\red186\green102\blue173;
+        \red73\green153\blue245;\red39\green159\blue171;\red88\green157\blue94;}
+        \pard\tx560\tx1120\tx1680\tx2240\pardirnatural\partightenfactor0
+
+        \f0\fs26 \cf2 import \cf3 java.io.BufferedReader;\
+        \
+        \cf2 class \cf3 FileTask \cf2 implements \cf3 Runnable \{\
+            \cf2 private \cf3 String \cf4 fileName\cf3 ;\
+        \
+            \cf2 public void \cf5 run\cf3 () \{\
+                \cf2 int \cf3 count = \cf6 0\cf3 ;\
+                content.append(line).append(\cf7 "\cf2 \\n\cf7 "\cf3 );\
+                \cf2 for \cf3 (String word : line.split(\cf7 "\cf2 \\\\\cf7 W+"\cf3 )) \{\
+                    count++;\
+                \}\
+                System.
+        \f1\i \cf4 out
+        \f0\i0 \cf3 .println(\cf7 "Java word is found " \cf3 + count);\
+            \}\
+        \}\
+        }
+        """;
+
+    [Fact]
+    public async Task Code_copied_from_an_IDE_keeps_its_text()
+    {
+        Assert.SkipUnless(fx.Catalog.StatusOf(fx.Converters.Single(c => c.Id == "libreoffice")).IsAvailable, "needs LibreOffice");
+        var rtf = Path.Combine(fx.NewFolder(), "FileTask.rtf");
+        await File.WriteAllTextAsync(rtf, IdeCode, TestContext.Current.CancellationToken);
+
+        var job = await fx.ConvertAsync([rtf], new Preset { TargetFormat = "txt" });
+        Assert.True(job.State == JobState.Completed, string.Join("; ", job.Files.Select(f => $"{f.ErrorKey} {f.ErrorDetail}")));
+        var lines = (await File.ReadAllTextAsync(job.Outputs.Single(), TestContext.Current.CancellationToken))
+            .TrimStart('\uFEFF').ReplaceLineEndings("\n").Split('\n');
+
+        Assert.DoesNotContain(lines, l => l.Contains('`'));
+        Assert.Equal("import java.io.BufferedReader;", lines[0]);
+        Assert.Equal("", lines[1]); // blank lines stay
+        Assert.Contains("    private String fileName;", lines); // and so does the indentation
+        Assert.Contains("        content.append(line).append(\"\\n\");", lines);
+        Assert.Contains("        for (String word : line.split(\"\\\\W+\")) {", lines);
+        Assert.Contains("        System.out.println(\"Java word is found \" + count);", lines); // the italic run
+    }
+}