diff --git a/.claude/settings.json b/.claude/settings.json
index bc49141de..0edc5ffd2 100644
--- a/.claude/settings.json
+++ b/.claude/settings.json
@@ -12,6 +12,13 @@
       "Bash(curl *)",
       "Bash(wget *)",
       "Bash(git push *)",
+      "Bash(gh pr merge *)",
+      "Bash(gh pr close *)",
+      "Bash(gh issue close *)",
+      "Bash(gh issue delete *)",
+      "Bash(gh release create *)",
+      "Bash(gh release delete *)",
+      "Bash(gh repo delete *)",
       "Bash(chmod 777 *)",
       "Read(**/.env)",
       "Read(**/.env.*)",
diff --git a/.devcontainer/devcontainer-lock.json b/.devcontainer/devcontainer-lock.json
new file mode 100644
index 000000000..cdd61126b
--- /dev/null
+++ b/.devcontainer/devcontainer-lock.json
@@ -0,0 +1,9 @@
+{
+  "features": {
+    "ghcr.io/devcontainers/features/github-cli:1": {
+      "version": "1.1.0",
+      "resolved": "ghcr.io/devcontainers/features/github-cli@sha256:d22f50b70ed75339b4eed1ba9ecde3a1791f90e88d37936517e3bace0bbad671",
+      "integrity": "sha256:d22f50b70ed75339b4eed1ba9ecde3a1791f90e88d37936517e3bace0bbad671"
+    }
+  }
+}
diff --git a/.devcontainer/devcontainer.json b/.devcontainer/devcontainer.json
index aa076add2..937ab0897 100644
--- a/.devcontainer/devcontainer.json
+++ b/.devcontainer/devcontainer.json
@@ -8,10 +8,13 @@
   "dockerComposeFile": ["../compose.yaml"],
   "mounts": [
     "source=${localEnv:HOME}/.ssh,target=/home/node/.ssh,type=bind,consistency=cached",
-    "source=${localEnv:HOME}/.claude,target=/home/node/.claude,type=bind,consistency=cached"
+    "source=${localEnv:HOME}/.claude,target=/home/node/.claude,type=bind,consistency=cached",
+    "source=${localEnv:HOME}/.gitconfig,target=/home/node/.gitconfig,type=bind,consistency=cached"
   ],
   // Features to add to the dev container. More info: https://containers.dev/features.
-  // "features": {},
+  "features": {
+    "ghcr.io/devcontainers/features/github-cli:1": {}
+  },
   //
   // Use 'forwardPorts' to make a list of ports inside the container available locally.
   "forwardPorts": [
@@ -22,10 +25,10 @@
   // "shutdownAction": "none",
   //
   // Use 'initializeCommand' to run commands before the container is created.
-  "initializeCommand": "mkdir -p ~/.claude",
+  "initializeCommand": "mkdir -p ~/.claude && touch ~/.gitconfig",
   //
   // Use 'postCreateCommand' to run commands after the container is created.
-  "postCreateCommand": "npm install -g @anthropic-ai/claude-code && (curl -fsSL https://cli.coderabbit.ai/install.sh | sh || echo 'CodeRabbit CLI installation failed, continuing...') && pnpm install",
+  "postCreateCommand": "bash .devcontainer/setup-devcontainer.sh",
   //
   // Configure tool-specific properties.
   "customizations": {
diff --git a/.devcontainer/setup-devcontainer.sh b/.devcontainer/setup-devcontainer.sh
new file mode 100644
index 000000000..4a4f1fd2d
--- /dev/null
+++ b/.devcontainer/setup-devcontainer.sh
@@ -0,0 +1,15 @@
+#!/bin/bash
+set -euo pipefail
+
+# Install Claude Code CLI
+npm install -g @anthropic-ai/claude-code
+
+# Install CodeRabbit CLI (continue if fails)
+curl -fsSL https://cli.coderabbit.ai/install.sh | sh || echo 'CodeRabbit CLI installation failed, continuing...'
+
+# Install RTK — token optimization proxy for AI coding assistants (60-90% reduction)
+curl -fsSL https://raw.githubusercontent.com/rtk-ai/rtk/master/install.sh | sh || echo 'RTK installation failed, continuing...'
+rtk init -g --auto-patch || echo 'RTK init failed, continuing...'
+
+# Install project dependencies
+pnpm install
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 63c04f796..31068f5a0 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -70,6 +70,7 @@
 
 - [Claude Code](https://docs.anthropic.com/en/docs/claude-code) - AI コーディングアシスタント（VS Code 拡張: `anthropic.claude-code`）
   - [superpowers plugin](https://github.com/obra/superpowers) - `/writing-plans` スキルによる実装前の詳細計画生成
+  - [RTK](https://github.com/rtk-ai/rtk) - AI コーディングアシスタント向けトークン最適化プロキシ（60–90% 削減）
 - [CodeRabbit](https://coderabbit.ai/) - AI コードレビュー
   - CodeRabbit CLI (`coderabbit review --plain`) — milestone 区切りでのローカルレビュー
   - CodeRabbit CI — PR 作成後の自動レビュー（最終品質ゲート）