fix: customised recipe to yaml string to avoid minininjia parsing error (#5494)

crates/goose/src/recipe/mod.rs

@@ -7,6 +7,7 @@ use std::path::Path;
 use crate::agents::extension::ExtensionConfig;
 use crate::agents::types::RetryConfig;
 use crate::recipe::read_recipe_file_content::read_recipe_file;
+use crate::recipe::yaml_format_utils::reformat_fields_with_multiline_values;
 use crate::utils::contains_unicode_tags;
 use serde::de::Deserializer;
 use serde::{Deserialize, Serialize};
@@ -18,6 +19,7 @@ pub mod read_recipe_file_content;
 mod recipe_extension_adapter;
 pub mod template_recipe;
 pub mod validate_recipe;
+pub mod yaml_format_utils;
 
 pub const BUILT_IN_RECIPE_DIR_PARAM: &str = "recipe_dir";
 pub const RECIPE_FILE_EXTENSIONS: &[&str] = &["yaml", "json"];
@@ -234,6 +236,14 @@ impl Recipe {
         false
     }
 
+    pub fn to_yaml(&self) -> Result<String> {
+        let recipe_yaml = serde_yaml::to_string(self)
+            .map_err(|err| anyhow::anyhow!("Failed to serialize recipe: {}", err))?;
+        let formatted_recipe_yaml =
+            reformat_fields_with_multiline_values(&recipe_yaml, &["prompt", "instructions"]);
+        Ok(formatted_recipe_yaml)
+    }
+
     pub fn builder() -> RecipeBuilder {
         RecipeBuilder {
             version: default_version(),

crates/goose/src/recipe/yaml_format_utils.rs

@@ -0,0 +1,122 @@
+use std::fmt::Write;
+
+/// Normalizes how `serde_yaml` outputs multi-line strings.
+/// It uses internal heuristics to decide between `|` and quoted text with escaped
+/// `\n` and `\"`, and the quoted form breaks MiniJinja parsing.
+/// Example before:
+///   prompt: "Hello \\\"World\\\"\\n{% if user == \\\"admin\\\" %}Welcome{% endif %}"
+/// After fix:
+///   prompt: |
+///     Hello "World"
+///     {% if user == "admin" %}Welcome{% endif %}
+pub fn reformat_fields_with_multiline_values(yaml: &str, multiline_fields: &[&str]) -> String {
+    let mut result = String::new();
+
+    for line in yaml.lines() {
+        let trimmed = line.trim_start();
+        if trimmed.is_empty() {
+            writeln!(result).unwrap();
+            continue;
+        }
+
+        let indent = line.len() - trimmed.len();
+        let indent_str = " ".repeat(indent);
+
+        let matched_field = multiline_fields
+            .iter()
+            .find(|&f| trimmed.starts_with(&format!("{f}: ")));
+
+        if let Some(field) = matched_field {
+            if let Some((_, raw_val)) = trimmed.split_once(": ") {
+                if raw_val.contains("\\n") {
+                    // Clean escaped content and unescape quotes
+                    let mut value = raw_val.trim_matches('"').to_string();
+
+                    // Unescape quotes and double backslashes (MiniJinja + newlines)
+                    value = value.replace("\\\"", "\"").replace("\\\\n", "\\n");
+
+                    writeln!(result, "{indent_str}{field}: |").unwrap();
+                    for l in value.split("\\n") {
+                        writeln!(result, "{indent_str}  {l}").unwrap();
+                    }
+                    continue;
+                }
+            }
+        }
+
+        writeln!(result, "{line}").unwrap();
+    }
+
+    let mut output = result.trim_end_matches('\n').to_string();
+    output.push('\n');
+    output
+}
+
+#[cfg(test)]
+mod tests {
+    use super::reformat_fields_with_multiline_values;
+
+    #[test]
+    fn keeps_simple_fields_unchanged() {
+        let yaml = "version: \"1.0\"\ntitle: \"Simple\"\nprompt: \"Hello\"";
+        let expected = "version: \"1.0\"\ntitle: \"Simple\"\nprompt: \"Hello\"\n";
+
+        let result = reformat_fields_with_multiline_values(yaml, &["prompt"]);
+        assert_eq!(result, expected);
+    }
+
+    #[test]
+    fn converts_multiline_prompt_to_literal_block() {
+        let yaml = "version: \"1.0\"\nprompt: \"line1\\\\nline2\"";
+        let expected = "version: \"1.0\"\nprompt: |\n  line1\n  line2\n";
+
+        let result = reformat_fields_with_multiline_values(yaml, &["prompt"]);
+        assert_eq!(result, expected);
+    }
+
+    #[test]
+    fn unescapes_quotes_inside_block() {
+        let yaml = "prompt: \"Hello \\\"World\\\"\\nHow are you?\"";
+        let expected = "prompt: |\n  Hello \"World\"\n  How are you?\n";
+
+        let result = reformat_fields_with_multiline_values(yaml, &["prompt"]);
+        assert_eq!(result, expected);
+    }
+
+    #[test]
+    fn preserves_unlisted_fields() {
+        let yaml = "version: \"1.0\"\nprompt: \"line1\\\\nline2\"\nnotes: \"note1\\\\nnote2\"";
+        let expected =
+            "version: \"1.0\"\nprompt: |\n  line1\n  line2\nnotes: \"note1\\\\nnote2\"\n";
+
+        let result = reformat_fields_with_multiline_values(yaml, &["prompt"]);
+        assert_eq!(result, expected);
+    }
+
+    #[test]
+    fn handles_indented_nested_field() {
+        let yaml = "settings:\n  prompt: \"line1\\\\nline2\"";
+        let expected = "settings:\n  prompt: |\n    line1\n    line2\n";
+
+        let result = reformat_fields_with_multiline_values(yaml, &["prompt"]);
+        assert_eq!(result, expected);
+    }
+
+    #[test]
+    fn ignores_existing_literal_blocks() {
+        let yaml = "prompt: |\n  already good\n  block";
+        let expected = "prompt: |\n  already good\n  block\n";
+
+        let result = reformat_fields_with_multiline_values(yaml, &["prompt"]);
+        assert_eq!(result, expected);
+    }
+
+    #[test]
+    fn ignores_fields_without_newlines() {
+        let yaml = "prompt: \"single line text\"";
+        let expected = "prompt: \"single line text\"\n";
+
+        let result = reformat_fields_with_multiline_values(yaml, &["prompt"]);
+        assert_eq!(result, expected);
+    }
+}