fix: use IndexMap and toml_edit for pantry serialization

- Switch PantryConf.sections from BTreeMap to IndexMap to preserve
  file order through parse-modify-write cycles.
- Enable toml's preserve_order feature so item order within sections
  is preserved too.
- Replace toml::to_string_pretty with toml_edit-based serialization
  in the public to_toml_string() / write() functions. This properly
  handles non-ASCII keys, uses inline tables for item attributes,
  and correctly serializes general (top-level) items.

Author: dubadub

Cargo.lock

@@ -27,7 +27,8 @@ unicase = "2.7.0"
 indexmap = { version = "2", features = ["serde"] }
 yansi = "1.0.1"
 serde_yaml = "0.9.34"
-toml = { version = "0.8", optional = true }
+toml = { version = "0.8", optional = true, features = ["preserve_order"] }
+toml_edit = { version = "0.22", optional = true }
 tsify = { version = "0.5", optional = true }
 wasm-bindgen = { version = "0.2", optional = true }
 
@@ -50,7 +51,7 @@ default = ["aisle", "bundled_units", "shopping_list"]
 bundled_units = ["toml", "prettyplease", "quote", "syn", "proc-macro2"]
 aisle = []
 shopping_list = []
-pantry = ["toml"]
+pantry = ["toml", "toml_edit"]
 ts = ["wasm-bindgen", "tsify"]
 
 [[bench]]

Cargo.toml

@@ -24,6 +24,8 @@ use std::{
     collections::{BTreeMap, HashMap},
 };
 
+use indexmap::IndexMap;
+
 use serde::{Deserialize, Serialize};
 use thiserror::Error;
 
@@ -40,9 +42,9 @@ use crate::{
 /// format.
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
 pub struct PantryConf {
-    /// Map of sections to their items (BTreeMap for consistent ordering)
+    /// Map of sections to their items (IndexMap to preserve file order)
     #[serde(flatten)]
-    pub sections: BTreeMap<String, Vec<PantryItem>>,
+    pub sections: IndexMap<String, Vec<PantryItem>>,
 
     /// Index for fast ingredient lookups (lowercase name -> (section, index))
     /// Using BTreeMap for better cache locality and predictable iteration
@@ -327,7 +329,7 @@ fn parse_core(
             message: "Expected TOML table at root".to_string(),
         })?;
 
-    let mut sections = BTreeMap::new();
+    let mut sections = IndexMap::new();
     let mut general_items = Vec::new(); // For top-level items
 
     for (section_name, section_value) in toml_table {
@@ -656,11 +658,74 @@ pub fn parse_lenient(input: &str) -> PassResult<PantryConf> {
     }
 }
 
+/// Serialize a [`PantryConf`] to a TOML string.
+///
+/// Uses `toml_edit` so that keys are properly escaped (including non-ASCII
+/// characters) and item attributes are written as inline tables.
+pub fn to_toml_string(conf: &PantryConf) -> String {
+    let mut doc = toml_edit::DocumentMut::new();
+
+    // General items go at the top level as plain strings (the parser treats
+    // top-level inline tables as section headers, not items).
+    if let Some(general_items) = conf.sections.get("general") {
+        for item in general_items {
+            doc[item.name()] = general_item_to_toml_item(item);
+        }
+    }
+
+    for (section_name, items) in &conf.sections {
+        if section_name == "general" {
+            continue;
+        }
+        let mut table = toml_edit::Table::new();
+        for item in items {
+            table[item.name()] = item_to_toml_item(item);
+        }
+        doc[section_name] = toml_edit::Item::Table(table);
+    }
+
+    doc.to_string()
+}
+
 /// Write a [`PantryConf`] in TOML format
 pub fn write(conf: &PantryConf, mut write: impl std::io::Write) -> std::io::Result<()> {
-    let toml_string = toml::to_string_pretty(conf)
-        .map_err(|e| std::io::Error::new(std::io::ErrorKind::Other, e))?;
-    write.write_all(toml_string.as_bytes())
+    write.write_all(to_toml_string(conf).as_bytes())
+}
+
+/// Convert a pantry item to an inline-table `toml_edit::Item` for use
+/// inside a `[section]`.
+fn item_to_toml_item(item: &PantryItem) -> toml_edit::Item {
+    match item {
+        PantryItem::Simple(_) => toml_edit::value(toml_edit::InlineTable::new()),
+        PantryItem::WithAttributes(attrs) => {
+            let mut table = toml_edit::InlineTable::new();
+            if let Some(qty) = &attrs.quantity {
+                table.insert("quantity", qty.as_str().into());
+            }
+            if let Some(bought) = &attrs.bought {
+                table.insert("bought", bought.as_str().into());
+            }
+            if let Some(expire) = &attrs.expire {
+                table.insert("expire", expire.as_str().into());
+            }
+            if let Some(low) = &attrs.low {
+                table.insert("low", low.as_str().into());
+            }
+            toml_edit::value(table)
+        }
+    }
+}
+
+/// Convert a pantry item to a plain-string `toml_edit::Item` for use at the
+/// top level ("general" section).  The parser only supports `key = "string"`
+/// at the top level.
+fn general_item_to_toml_item(item: &PantryItem) -> toml_edit::Item {
+    match item {
+        PantryItem::Simple(_) => toml_edit::value(""),
+        PantryItem::WithAttributes(attrs) => {
+            toml_edit::value(attrs.quantity.as_deref().unwrap_or(""))
+        }
+    }
 }
 
 /// Error generated by [`parse`].
@@ -987,7 +1052,7 @@ rice = "5%kg"
     #[test]
     fn test_index_performance() {
         // Create a large pantry to test performance
-        let mut sections = BTreeMap::new();
+        let mut sections = IndexMap::new();
 
         // Add 100 sections with 100 items each = 10,000 items
         for section_num in 0..100 {