+
+
+
+
+
+
diff --git a/lht-cmn/FEEDBACK.md b/lht-cmn/FEEDBACK.md
new file mode 100644
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--- /dev/null
+++ b/lht-cmn/FEEDBACK.md
@@ -0,0 +1,54 @@
+# lht-cmn Feedback
+
+## 2026-03-08 `lht-command-block` style contract gap
+
+- 症状:
+ - `lht-command-block` をページ側で利用しても、`lht-cmn/css/components.css` だけでは「角丸四角の結果表示ブロック」として視覚的に完成しない
+ - 実際には `md-code-block` / `md-code` / `md-copy-button` / `md-icon-button.md-copy-button` 相当の見た目をページ側 CSS が別途持っている前提になっている
+- 問題:
+ - `lht-command-block` を共通部品として使っても、利用ページごとに結果表示の見た目が欠けうる
+ - `lht-cmn` の self-contained 方針とずれている
+- 期待:
+ - `lht-command-block` は `lht-cmn/css/components.css` だけで最低限の完成した見た目になるべき
+ - 少なくとも以下の visual contract は `lht-cmn` 側に同梱する
+ - `.md-code-block`
+ - `.md-code`
+ - `.md-copy-button`
+ - `md-icon-button.md-copy-button`
+ - `md-icon-button.md-copy-button--surface`
+- 補足:
+ - 今回 `docs/prompt/prompt-gen-src.html` では、既存画面に合わせるためページ側へ上記スタイルを追加して回避した
+ - 根本対応は `lht-cmn` 側で行うべき
+
+## 2026-03-08 `lht-switch-help` material bundle gap
+
+- 症状:
+ - `lht-switch-help` を利用しても、ページ側で `md-switch` が未登録のため fallback 実装に落ちる
+ - `prompt-gen` では text field は Material 表示なのに switch だけ fallback 表示になる
+- 問題:
+ - `lht-*` を使っても、入力部品ごとに Material / fallback が混在しやすい
+ - ページ側から見ると `lht-switch-help` の見た目が他の Material 部品と揃わず、利用側で原因が見えにくい
+- 期待:
+ - `lht-switch-help` も `lht-cmn` 側で Material 実装を self-contained に利用できる形に寄せたい
+ - 少なくとも `md-switch` 用 bundle の vendor / 読み込み導線を `lht-cmn` 側で用意したい
+ - それが難しい場合でも、README に「switch は fallback 前提になりうる」ことを明記したい
+- 補足:
+ - 現状の `lht-switch-help` は `window.customElements.get("md-switch")` が false のとき fallback DOM を生成する実装になっている
+ - `lht-cmn/vendor` には `material-web-outlined-text-field.bundle.js` はあるが、`md-switch` 相当の bundle は見当たらない
+
+## 2026-03-09 `lht-text-field-help` trailing action gap
+
+- 症状:
+ - `prompt-gen` で「やりたいこと」入力欄に `×` クリアボタンを付けたかったが、`lht-text-field-help` 自体には trailing action / trailing icon を安全に差し込む契約がない
+ - 外付け absolute 配置では、Material 側の見た目中心と合いにくく、位置合わせが不安定だった
+- 問題:
+ - 画面ごとに似た「入力クリア」「末尾アイコン」「補助アクション」実装が再発しやすい
+ - `lht-text-field-help` を使っていても、入力欄内アクションはページ側の局所 CSS に依存しやすい
+ - fallback 実装と Material 実装で、末尾アクションの見た目や余白が揃いにくい
+- 期待:
+ - `lht-text-field-help` に trailing action slot、または `clearable` のような共通機能を検討したい
+ - もし汎用化しない場合でも、「入力欄右端に後付けアクションを重ねる時の推奨パターン」を README に明記したい
+- 補足:
+ - 今回は暫定対応として `lht-text-field-help` に `clearable` 属性をローカル追加し、`prompt-gen` ではそれを利用する形へ寄せた
+ - ただしこれは prompt-gen 都合で先に入れた provisional API なので、`lht-cmn` チーム側では trailing action 全般を扱える正式な契約として見直したい
+ - 正式方針が固まったら、今回の `clearable` 実装や CSS 調整はレビューのうえ置き換えたい
diff --git a/lht-cmn/LICENSE b/lht-cmn/LICENSE
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--- /dev/null
+++ b/lht-cmn/LICENSE
@@ -0,0 +1,197 @@
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+ any Contribution intentionally submitted for inclusion in the Work
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diff --git a/lht-cmn/NOTICE b/lht-cmn/NOTICE
new file mode 100644
index 0000000..d1b7fb9
--- /dev/null
+++ b/lht-cmn/NOTICE
@@ -0,0 +1,11 @@
+Copyright 2026 Toshiki Iga
+
+This product includes software developed by Toshiki Iga.
+
+Design direction:
+- 本プロジェクトは Material Design 3 の設計原則を参照しています。
+
+Third-party component implementation:
+- `lht-cmn` の内部実装では、必要に応じて Material Web（`@material/web`）を優先利用します。
+- Material Web のライセンスは Apache License, Version 2.0 です。
+- Source: https://github.com/material-components/material-web
diff --git a/lht-cmn/README.md b/lht-cmn/README.md
new file mode 100644
index 0000000..e7dad3c
--- /dev/null
+++ b/lht-cmn/README.md
@@ -0,0 +1,408 @@
+# lht-cmn
+
+`lht-cmn` は `local-html-tools` 全体で共有する UI コンポーネント基盤です。
+
+- Version: `v20260308`
+- License: Apache License 2.0 (`lht-cmn/LICENSE`)
+- Copyright: Toshiki Iga
+
+## ライセンスと帰属
+
+- `lht-cmn` 自体は Apache License 2.0 で配布します。
+- デザイン方針は Material Design 3 の設計原則を参照します。
+- 実装技術として、`lht-cmn` は必要に応じて Material Web（`@material/web`）を優先利用します。
+- Material Web のライセンスは Apache License 2.0 です。
+- 帰属情報の詳細は `lht-cmn/NOTICE` に記載します。
+
+## 目的
+
+`local-html-tools` では、入力・選択・ヘルプ・コピー・メニューなどの UI を複数ページで繰り返し実装してきました。
+`lht-cmn` はこの重複を減らし、UI を `lht-*` Web Components として共通化するためのレイヤーです。
+
+## 基本方針
+
+- デザイン基準は Material Design 3
+- 画面側の公開 UI レイヤーは常に `lht-*` とし、`md-*` を直接使わせない
+- `lht-*` は self-contained を原則とし、アプリ側へ `md-*` の登録責務を漏らさない
+- 実現手段として Material Web を優先利用してよい
+- ただし Material 利用の有無に関わらず、`lht-*` は最低保証で壊れないことを優先する
+- 内部実装として許可する型は次の 2 つに限定する:
+ - `md-*` 優先 + fallback
+ - 完全自前実装
+- 「Material 依存で fallback なし」は原則避け、採る場合は README に明示する
+- fallback は Material の完全再現ではなく、公開 API の最低保証に留める
+
+## メリット
+
+- 画面ごとの重複実装を削減できる
+- 見た目と挙動（必須表示、ヘルプ表示、フォーカス時の挙動）を統一できる
+- 変更点を `lht-cmn` に集約でき、保守・レビューがしやすくなる
+- 単一HTML生成前提でも、開発時の部品再利用性を維持できる
+- 変更点が局所化され、生成AIが誤って別画面を壊す確率が下がる
+- UI規約が `lht-*` に集約され、提案が毎回同じ型で出せる
+- レビュー時に「画面の見た目差分」より「共通部品の差分」を見ればよくなり、判断が速くなる
+
+## 運用方針（重要）
+
+- 画面側（`docs/*-src.html`）は `lht-*` を利用し、`md-*` 直接実装の追加は原則避ける
+- `lht-cmn/js/components.js` を共通コンポーネントの正本とする
+- `lht-cmn/css/components.css` を実運用スタイルの正本とする
+- `lht-cmn/` 配下（特に `js/components.js` / `css/components.css`）の変更は、必ずユーザーの明示許可を得てから実施する
+- `md3/` は段階的にリファレンス用途へ縮退し、実運用スタイルは `lht-cmn` に集約する
+
+## 構成
+
+- `lht-cmn/js/components.js`
+ - 共通 Web Components 定義
+- `lht-cmn/css/components.css`
+ - 上記コンポーネントの共通スタイル
+- `lht-cmn/catalog/index.html`
+ - 実表示と HTML 利用例を並べて確認するコンポーネントカタログ
+
+### コンポーネント一覧
+
+| コンポーネント | できること | 内部構造（概要） |
+|---|---|---|
+| `lht-help-tooltip` | `(i)` ヘルプアイコンとツールチップを1タグで配置できる | `md-icon-button` が使える環境ではそれを利用し、未定義時はネイティブ `button` fallback を生成。タグ内HTMLをツールチップ本文へ差し込む |
+| `lht-text-field-help` | ラベル付き入力（単一行/複数行）とフォーカス時ヘルプ表示を共通化できる | `md-outlined-text-field` が使える環境ではそれを利用し、未定義時はネイティブ `input` / `textarea` fallback を生成。属性（`field-id`/`label`/`type`/`rows` など）を透過する |
+| `lht-select-help` | ラベル付きドロップダウンとヘルプ表示を共通化できる | 内部で `md-outlined-select` を生成し、`` を使用する
+3. `lht-select-help` で `
+ 
+ 
+ 
+