docs: Add comprehensive rustdoc to src/db.rs structs and functions

Co-authored-by: aider (openai/andrew/openrouter/deepseek/deepseek-chat-v3.1) <aider@aider.chat>

src/db.rs

@@ -9,6 +9,8 @@ use std::collections::HashMap;
 use std::path::PathBuf;
 use std::rc::Rc;
 
+/// Database schema migrations for the Keep application
+
 lazy_static! {
     static ref MIGRATIONS: Migrations<'static> = Migrations::new(vec![
         M::up(
@@ -38,27 +40,48 @@ lazy_static! {
     ]);
 }
 
+/// Represents an item stored in the database
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct Item {
+    /// Unique identifier for the item, None for new items
     pub id: Option<i64>,
+    /// Timestamp when the item was created
     pub ts: DateTime<Utc>,
+    /// Size of the item content in bytes, None if not set
     pub size: Option<i64>,
+    /// Compression algorithm used for the item content
     pub compression: String,
 }
 
+/// Represents a tag associated with an item
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct Tag {
+    /// ID of the item this tag belongs to
     pub id: i64,
+    /// Name of the tag
     pub name: String,
 }
 
+/// Represents metadata associated with an item
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct Meta {
+    /// ID of the item this metadata belongs to
     pub id: i64,
+    /// Name of the metadata field
     pub name: String,
+    /// Value of the metadata field
     pub value: String,
 }
 
+/// Opens a database connection and ensures the schema is up to date
+///
+/// # Arguments
+///
+/// * `path` - Path to the SQLite database file
+///
+/// # Returns
+///
+/// * `Result<Connection, Error>` - A SQLite connection on success, or an error if opening or migration fails
 pub fn open(path: PathBuf) -> Result<Connection, Error> {
     debug!("DB: Opening file: {:?}", path);
     let mut conn = Connection::open_with_flags(
@@ -79,6 +102,16 @@ pub fn open(path: PathBuf) -> Result<Connection, Error> {
     Ok(conn)
 }
 
+/// Inserts a new item into the database
+///
+/// # Arguments
+///
+/// * `conn` - Database connection
+/// * `item` - Item to insert
+///
+/// # Returns
+///
+/// * `Result<i64>` - The ID of the newly inserted item on success, or an error if insertion fails
 pub fn insert_item(conn: &Connection, item: Item) -> Result<i64> {
     debug!("DB: Inserting item: {:?}", item);
     conn.execute(
@@ -88,6 +121,16 @@ pub fn insert_item(conn: &Connection, item: Item) -> Result<i64> {
     Ok(conn.last_insert_rowid())
 }
 
+/// Creates a new item in the database with the current timestamp
+///
+/// # Arguments
+///
+/// * `conn` - Database connection
+/// * `compression_type` - Compression type to use for the item
+///
+/// # Returns
+///
+/// * `Result<Item>` - The created item with its ID set, or an error if creation fails
 pub fn create_item(conn: &Connection, compression_type: crate::compression_engine::CompressionType) -> Result<Item> {
     let item = Item {
         id: None,
@@ -102,6 +145,17 @@ pub fn create_item(conn: &Connection, compression_type: crate::compression_engin
     })
 }
 
+/// Adds a tag to an item
+///
+/// # Arguments
+///
+/// * `conn` - Database connection
+/// * `item_id` - ID of the item to tag
+/// * `tag_name` - Name of the tag to add
+///
+/// # Returns
+///
+/// * `Result<()>` - Success or error if the operation fails
 pub fn add_tag(conn: &Connection, item_id: i64, tag_name: &str) -> Result<()> {
     let tag = Tag {
         id: item_id,
@@ -110,6 +164,18 @@ pub fn add_tag(conn: &Connection, item_id: i64, tag_name: &str) -> Result<()> {
     insert_tag(conn, tag)
 }
 
+/// Adds metadata to an item
+///
+/// # Arguments
+///
+/// * `conn` - Database connection
+/// * `item_id` - ID of the item
+/// * `name` - Name of the metadata field
+/// * `value` - Value of the metadata field
+///
+/// # Returns
+///
+/// * `Result<()>` - Success or error if the operation fails
 pub fn add_meta(conn: &Connection, item_id: i64, name: &str, value: &str) -> Result<()> {
     let meta = Meta {
         id: item_id,