diff --git a/.claude/bootstrap.sh b/.claude/bootstrap.sh
new file mode 100644
index 0000000..4d5a421
--- /dev/null
+++ b/.claude/bootstrap.sh
@@ -0,0 +1,12 @@
+#!/bin/sh
+# Idempotent dev-tooling bootstrap for Makefile-based (shell/python) repos.
+# Installs the pip-installable lint tools `make check` needs so it works in a cloud session.
+# (ShellCheck itself is usually pre-installed in the web sandbox.) No-op once ruff is present.
+dir="${CLAUDE_PROJECT_DIR:-$(cd "$(dirname "$0")/.." && pwd)}"
+cd "$dir" || exit 0
+
+if [ -f Makefile ] && ! command -v ruff >/dev/null 2>&1; then
+  pip install --quiet ruff codespell 2>/dev/null || true
+fi
+
+exit 0
diff --git a/.claude/settings.json b/.claude/settings.json
new file mode 100644
index 0000000..a844622
--- /dev/null
+++ b/.claude/settings.json
@@ -0,0 +1,15 @@
+{
+  "hooks": {
+    "SessionStart": [
+      {
+        "matcher": "startup|resume",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "sh \"$CLAUDE_PROJECT_DIR/.claude/bootstrap.sh\""
+          }
+        ]
+      }
+    ]
+  }
+}
diff --git a/.claude/skills/run-checks/SKILL.md b/.claude/skills/run-checks/SKILL.md
new file mode 100644
index 0000000..3e66b51
--- /dev/null
+++ b/.claude/skills/run-checks/SKILL.md
@@ -0,0 +1,11 @@
+---
+name: run-checks
+description: Run agmsg-kit's checks (smoke roundtrip, safety, shell lint). Use when asked to test, lint, verify, or check the installer/patches.
+---
+
+Run the repo checks and report results concisely.
+
+1. Ensure lint tools are present (SessionStart bootstrap pip-installs `ruff`+`codespell`; `shellcheck` is usually pre-installed on web).
+2. Targets: `make test` (smoke roundtrip + patch regressions), `make safety` (secret_redact + SQL-escaping/suggest regressions), `make check` (= lint + test + safety). Patch integrity: `make verify-patches`.
+3. Summarize: which target passed/failed and the first failing assertion/file per failure.
+4. Do not edit scripts or patches unless asked; the upstream pin + patch set are load-bearing.
diff --git a/README.md b/README.md
index 2d64cfc..e81236a 100644
--- a/README.md
+++ b/README.md
@@ -68,3 +68,12 @@ the chain. See `docs/GOVERNANCE.md` and `SECURITY.md`.
 
 MIT. Upstream agmsg (MIT) is fetched at install time at the pinned commit in
 `VENDORED.md`, not redistributed here.
+
+## Claude Code で使う (web / cloud 対応)
+
+このリポジトリは **Claude Code on the web** に対応しています。
+
+- lint ツール（ruff/codespell）は `.claude/bootstrap.sh`（SessionStart）が pip で自動インストール。`make test`（smoke roundtrip）は追加依存なし。
+- クラウドセッションは `AGENTS.md` と `.claude/skills/`（例: `run-checks`）を自動ロード。
+- MCP は本リポジトリではローカル専用。詳細は
+  [`.github/docs/claude-code-web-readiness.md`](https://github.com/thinkyou0714/.github/blob/main/docs/claude-code-web-readiness.md)。