Added some documents.

README.ja.md

@@ -10,5 +10,11 @@
 - **馴染みの関連 API で高速参照**: `belongs_to` / `has_many` 風のインターフェースを DB ではなくオンメモリ上で処理し、N+1 を気にしなくてよい速度で動作。
 - **COW フレンドリーで多プロセス共有**: レコードは freeze され、Copy-on-Write を活かしてフォークプロセス間でメモリを効率共有できる。
 
+## ドキュメント
+- 導入ガイド: [English](docs/simple_master_guide_en.md) / [日本語](docs/simple_master_guide_ja.md)
+- カラム仕様: [English](docs/simple_master_columns_en.md) / [日本語](docs/simple_master_columns_ja.md)
+- Dataset / Table: [English](docs/simple_master_dataset_en.md) / [日本語](docs/simple_master_dataset_ja.md)
+- Association: [English](docs/simple_master_associations_en.md) / [日本語](docs/simple_master_associations_ja.md)
+
 ## ライセンス
 MIT ライセンスです。詳細は [LICENSE](LICENSE) を参照してください。

README.md

@@ -9,5 +9,11 @@ In game development and other domains, configuration/definition datasets are oft
 - **Familiar associations, very fast**: `belongs_to` / `has_many`-style API resolved in memory, fast enough that N+1 is rarely a concern.
 - **COW-friendly for multi-process**: records are frozen, making Copy-on-Write efficient when sharing memory across forked processes.
 
+## Documentation
+- Getting Started Guide: [English](docs/simple_master_guide_en.md) / [日本語](docs/simple_master_guide_ja.md)
+- Columns: [English](docs/simple_master_columns_en.md) / [日本語](docs/simple_master_columns_ja.md)
+- Dataset / Table: [English](docs/simple_master_dataset_en.md) / [日本語](docs/simple_master_dataset_ja.md)
+- Associations: [English](docs/simple_master_associations_en.md) / [日本語](docs/simple_master_associations_ja.md)
+
 ## License
 MIT License. See [LICENSE](LICENSE) for details.

docs/simple_master_associations_en.md

@@ -0,0 +1,51 @@
+# SimpleMaster Associations (English)
+
+> 日本語版: [simple_master_associations_ja.md](simple_master_associations_ja.md)
+
+## Overview
+SimpleMaster provides `belongs_to`, `has_one`, `has_many`, and `has_many :through`.
+
+## Definitions
+```ruby
+class Player < ApplicationRecord
+  belongs_to :level, foreign_key: :lv, primary_key: :lv
+  has_many :player_items
+end
+```
+
+```ruby
+class Reward < ApplicationMaster
+  belongs_to :enemy
+  belongs_to :reward, polymorphic: true
+end
+```
+
+The lookup path depends on whether the target is `SimpleMaster::Master`
+or `ActiveRecord::Base`.
+
+- Master to Master: use `all_by` / `find_by`
+  - These are fast, so values are fetched on each call. Cache in a variable if used often.
+- ActiveRecord: use `simple_master_connection`
+  - `belongs_to_store` / `has_many_store` (RequestStore) caches per request.
+
+## Common options
+### `class_name:`
+- Example: `belongs_to :reward, class_name: "Weapon"`
+- Explicitly sets the target class.
+
+### `foreign_key:`
+- Example: `has_many :players, foreign_key: :lv`
+- Sets the foreign key column.
+
+### `primary_key:`
+- Example: `belongs_to :level, primary_key: :lv`
+- Sets the target primary key (default is `:id`).
+
+## Association types
+- `belongs_to` : `belongs_to :enemy`
+- `belongs_to (polymorphic)` : `belongs_to :reward, polymorphic: true`
+  - Requires `def_column :reward_type, polymorphic_type: true`
+- `has_one` : `has_one :profile`
+- `has_many` : `has_many :players, foreign_key: :lv`
+- `has_many :through` : `has_many :items, through: :player_items`
+  - `source:` can rename the target association

docs/simple_master_associations_ja.md

@@ -0,0 +1,50 @@
+# SimpleMaster Association 仕様 (日本語)
+
+> English version: [simple_master_associations_en.md](simple_master_associations_en.md)
+
+## 全体説明
+SimpleMaster の Association は `belongs_to` / `has_one` / `has_many` / `has_many :through` を提供します。
+
+## 定義方法
+```ruby
+class Player < ApplicationRecord
+  belongs_to :level, foreign_key: :lv, primary_key: :lv
+  has_many :player_items
+end
+```
+
+```ruby
+class Reward < ApplicationMaster
+  belongs_to :enemy
+  belongs_to :reward, polymorphic: true
+end
+```
+
+対象が `SimpleMaster::Master` か `ActiveRecord::Base` かで参照方法が変わります。
+
+- Master 同士: `all_by` / `find_by` を使った参照
+  - 取得が高速なため、都度引き直しとなります。利用時に呼ぶ回数多いなら、変数に格納してください。
+- ActiveRecord: `simple_master_connection` で DB 参照
+  - `belongs_to_store` / `has_many_store` (RequestStore) に保持されるため、リクエストごとにキャッシュが効きます。
+
+## 共通オプション
+### `class_name:`
+- 例: `belongs_to :reward, class_name: "Weapon"`
+- 明示的に参照先クラスを指定します。
+
+### `foreign_key:`
+- 例: `has_many :players, foreign_key: :lv`
+- 外部キー名を指定します。
+
+### `primary_key:`
+- 例: `belongs_to :level, primary_key: :lv`
+- 参照先のキーを指定します（デフォルトは `:id`）。
+
+## Association 種別
+- `belongs_to` : `belongs_to :enemy`
+- `belongs_to (polymorphic)` : `belongs_to :reward, polymorphic: true`
+  - 前提: `def_column :reward_type, polymorphic_type: true`
+- `has_one` : `has_one :profile`
+- `has_many` : `has_many :players, foreign_key: :lv`
+- `has_many :through` : `has_many :items, through: :player_items`
+  - `source:` を指定すると参照先の名前を変更できます。

docs/simple_master_columns_en.md

@@ -0,0 +1,199 @@
+# SimpleMaster Columns (English)
+
+> 日本語版: [simple_master_columns_ja.md](simple_master_columns_ja.md)
+
+## Overview
+SimpleMaster columns are defined with `def_column`. At load time, type conversion,
+cache helpers, and accessor methods are generated.
+The behavior depends on `type` and DSL options.
+
+```ruby
+class Weapon < ApplicationMaster
+  def_column :id
+  def_column :name, type: :string
+  def_column :attack, type: :float
+  def_column :rarity
+
+  enum :rarity, { common: 0, rare: 1, epic: 2 }
+end
+```
+
+## Common options
+### `type:`
+- Example: `def_column :attack, type: :float`
+- See the column type list below.
+
+### `group_key:`
+- Example: `def_column :lv, type: :integer, group_key: true`
+- You can also use `group_key :lv`.
+
+### `db_column_name:`
+- Use when the DB column name differs.
+- Example: `def_column :start_at, type: :time, db_column_name: :start_time`
+
+### `globalize:`
+- Adds locale-aware values using `I18n.locale`.
+- Example: `def_column :name, globalize: true`
+- You can also use `globalize :name`.
+- Translation values live in `@_globalized_name` like `{ en: "Storm Edge", ja: "..." }`.
+- Not supported on `id` / `enum` / `bitmask` / `sti` / `polymorphic_type`.
+- Cannot be used with `group_key`.
+
+## Column types
+
+### id (IdColumn)
+**Usage**
+```ruby
+def_column :id
+```
+**Behavior**
+- Converts to `to_i` on assignment.
+- In tests, updates `id_hash` when changed.
+
+### integer
+**Usage**
+```ruby
+def_column :lv, type: :integer
+```
+**Behavior**
+- Converts to `to_i` on assignment (empty string becomes `nil`).
+
+### float
+**Usage**
+```ruby
+def_column :attack, type: :float
+```
+**Behavior**
+- Converts to `to_f` on assignment (empty string becomes `nil`).
+
+### string
+**Usage**
+```ruby
+def_column :name, type: :string
+```
+**Behavior**
+- Converts to `to_s` on assignment.
+- Values are cached to reuse identical objects (`object_cache`).
+
+### symbol
+**Usage**
+```ruby
+def_column :kind, type: :symbol
+```
+**Behavior**
+- Converts to `to_s` + `to_sym` on assignment.
+- SQL/CSV output uses a string.
+
+### boolean
+**Usage**
+```ruby
+def_column :is_boss, type: :boolean
+```
+**Behavior**
+- Integers use 0/1, strings accept "true" or "1".
+- Adds a `name?` predicate.
+- SQL/CSV output is 0/1.
+
+### json
+**Usage**
+```ruby
+def_column :info, type: :json
+```
+**Options**
+- `symbolize_names: true` converts JSON keys to symbols.
+
+**Behavior**
+- Parses string values with `JSON.parse`.
+- SQL/CSV output uses `JSON.generate`.
+- Non-string assignments are not transformed by `symbolize_names`.
+
+### time
+**Usage**
+```ruby
+def_column :start_at, type: :time
+```
+**Options**
+- `db_type: :time` outputs `HH:MM:SS` only.
+
+**Behavior**
+- Parses strings with `Date._parse` into `Time`.
+- Sub-seconds are truncated.
+
+### enum
+**Usage**
+```ruby
+def_column :rarity, enum: { common: 0, rare: 1, epic: 2 }
+# or
+def_column :rarity
+enum :rarity, { common: 0, rare: 1, epic: 2 }
+```
+**Options**
+- `prefix`, `suffix` add a prefix/suffix to predicates.
+  - `prefix: true` => `rarity_common?`
+  - `suffix: :rarity` => `common_rarity?`
+
+**Behavior**
+- Values are stored as symbols.
+- Adds `rarities` and `rarity_before_type_cast`.
+- Predicate methods (e.g. `common?`) are generated.
+
+### bitmask
+**Usage**
+```ruby
+def_column :flags, type: :integer
+bitmask :flags, as: [:tradeable, :soulbound, :limited]
+```
+**Behavior**
+- Accepts array/symbol/integer and converts to bit integer.
+- `flags` returns an array of symbols.
+- Adds `flags_value` / `flags_value=` for raw integer bits.
+
+### sti (STI type column)
+**Usage**
+```ruby
+def_column :type, sti: true
+```
+**Behavior**
+- Converts `type` to a string.
+- Defines `sti_base_class` and `sti_column`.
+- Loader should resolve classes by `type`.
+
+### polymorphic_type
+**Usage**
+```ruby
+def_column :reward_type, polymorphic_type: true
+```
+**Behavior**
+- Used for `belongs_to polymorphic` type columns.
+- Stores a class name string and sets `reward_type_class`.
+- Empty strings become `nil`.
+
+## Custom column types
+Define custom columns by subclassing `SimpleMaster::Master::Column`.
+If the class name ends with `Column`, the `type` is auto-registered.
+
+```ruby
+class MoneyColumn < SimpleMaster::Master::Column
+  private
+
+  def code_for_conversion
+    <<-RUBY
+      value = value&.to_i
+    RUBY
+  end
+
+  def code_for_sql_value
+    <<-RUBY
+      #{name}
+    RUBY
+  end
+end
+
+class Product < ApplicationMaster
+  def_column :price, type: :money
+end
+```
+
+- Ensure the file is loaded before use.
+- Override `init` if you need custom methods.
+- See [lib/simple_master/master/column.rb](lib/simple_master/master/column.rb).