diff --git a/.chezmoidata/packages.yaml b/.chezmoidata/packages.yaml
new file mode 100644
index 0000000..acca3fa
--- /dev/null
+++ b/.chezmoidata/packages.yaml
@@ -0,0 +1,7 @@
+---
+# Package declarations for declarative installation
+# Packages are installed via run_onchange scripts that execute when this file changes
+
+npm:
+  global:
+    - "@anthropic-ai/claude-code"
diff --git a/.chezmoiscripts/run_onchange_after_install-npm-packages.sh.tmpl b/.chezmoiscripts/run_onchange_after_install-npm-packages.sh.tmpl
new file mode 100755
index 0000000..ee3b45d
--- /dev/null
+++ b/.chezmoiscripts/run_onchange_after_install-npm-packages.sh.tmpl
@@ -0,0 +1,41 @@
+#!/bin/bash
+# Install npm packages declaratively based on .chezmoidata/packages.yaml
+# This script runs when the package list changes
+
+{{ if .include_defaults -}}
+set -e
+
+# Function to run npm commands via mise
+run_npm() {
+    if command -v mise >/dev/null 2>&1; then
+        mise exec -- npm "$@"
+    else
+        npm "$@"
+    fi
+}
+
+# Check if npm is available (via mise or directly)
+if command -v mise >/dev/null 2>&1; then
+    if ! mise exec -- npm --version >/dev/null 2>&1; then
+        echo "⚠️  Node.js/npm not available via mise. Skipping npm package installation."
+        exit 0
+    fi
+elif ! command -v npm >/dev/null 2>&1; then
+    echo "⚠️  npm not found. Skipping npm package installation."
+    exit 0
+fi
+
+# Install global npm packages
+{{ if .npm.global -}}
+{{ range .npm.global -}}
+if ! run_npm list -g "{{ . }}" >/dev/null 2>&1; then
+    echo "📦 Installing {{ . }}..."
+    run_npm install -g "{{ . }}"
+    echo "✓ Installed {{ . }}"
+else
+    echo "✓ {{ . }} already installed"
+fi
+{{ end -}}
+{{ end -}}
+
+{{ end -}}
diff --git a/.claude/skills/chezmoi-development/SKILL.md b/.claude/skills/chezmoi-development/SKILL.md
index 1519136..4dd0cf8 100644
--- a/.claude/skills/chezmoi-development/SKILL.md
+++ b/.claude/skills/chezmoi-development/SKILL.md
@@ -562,6 +562,80 @@ if ! command -v jq &> /dev/null; then
 fi
 ```
 
+## Declarative Package Installation
+
+Chezmoi can install packages declaratively using a combination of `.chezmoidata/packages.yaml` and `run_onchange_` scripts. This pattern ensures packages are installed when the package list changes.
+
+### Pattern: npm Package Installation
+
+**1. Declare packages in `.chezmoidata/packages.yaml`:**
+```yaml
+---
+# Package declarations for declarative installation
+# Top-level keys become template variables (e.g., .npm, .apt, .brew)
+npm:
+  global:
+    - "@anthropic-ai/claude-code"
+    - "typescript"
+```
+
+**2. Create installation script `.chezmoiscripts/run_onchange_after_install-npm-packages.sh.tmpl`:**
+```bash
+#!/bin/bash
+# Install npm packages declaratively based on .chezmoidata/packages.yaml
+# This script runs when the package list changes
+
+{{ if .include_defaults -}}
+set -e
+
+# Function to run npm commands via mise
+run_npm() {
+    if command -v mise >/dev/null 2>&1; then
+        mise exec -- npm "$@"
+    else
+        npm "$@"
+    fi
+}
+
+# Check if npm is available (via mise or directly)
+if command -v mise >/dev/null 2>&1; then
+    if ! mise exec -- npm --version >/dev/null 2>&1; then
+        echo "⚠️  Node.js/npm not available via mise. Skipping npm package installation."
+        exit 0
+    fi
+elif ! command -v npm >/dev/null 2>&1; then
+    echo "⚠️  npm not found. Skipping npm package installation."
+    exit 0
+fi
+
+# Install global npm packages
+{{ if .npm.global -}}
+{{ range .npm.global -}}
+if ! run_npm list -g "{{ . }}" >/dev/null 2>&1; then
+    echo "📦 Installing {{ . }}..."
+    run_npm install -g "{{ . }}"
+    echo "✓ Installed {{ . }}"
+else
+    echo "✓ {{ . }} already installed"
+fi
+{{ end -}}
+{{ end -}}
+
+{{ end -}}
+```
+
+**How it works:**
+- The script template references `.npm.global` from `.chezmoidata/packages.yaml`
+- `run_onchange_` prefix means the script executes when its rendered content changes
+- When you add/remove packages in `packages.yaml`, the rendered script changes, triggering re-execution
+- Each package is checked before installation to avoid redundant installs
+- Uses `mise exec` to ensure npm is available from mise-managed Node.js
+
+**Adaptable to other package managers:**
+- apt: Create `.chezmoidata/packages.yaml` with `apt: [...]` and use `{{ range .apt }}`
+- brew: Create with `brew: [...]` and use `{{ range .brew }}`
+- pip: Create with `pip: [...]` and use `{{ range .pip }}`
+
 ## Reference Documentation
 
 For a complete, working example of this pattern, see:
diff --git a/test/test-coder-existing.sh b/test/test-coder-existing.sh
index f72a9fe..cf04e32 100755
--- a/test/test-coder-existing.sh
+++ b/test/test-coder-existing.sh
@@ -4,7 +4,7 @@ set -e
 
 # Create existing ~/.claude with user content
 mkdir -p "$HOME/.claude"
-echo "user_settings" > "$HOME/.claude/settings.json"
+echo '{"alwaysThinkingEnabled":true,"userSetting":"value"}' > "$HOME/.claude/settings.json"
 echo "user_custom" > "$HOME/.claude/custom.txt"
 
 # Run setup
diff --git a/test/verify-marketplace.sh b/test/verify-marketplace.sh
index d2ce88e..dfca221 100755
--- a/test/verify-marketplace.sh
+++ b/test/verify-marketplace.sh
@@ -1,7 +1,13 @@
 #!/bin/bash
-# Verify marketplace configuration
+# Verify marketplace configuration and npm packages
 set -e
 
+# Ensure mise is activated if available
+if command -v mise >/dev/null 2>&1; then
+    export PATH="$HOME/.local/bin:$PATH"
+    eval "$(mise activate bash 2>/dev/null)" || true
+fi
+
 if [ ! -f "$HOME/.claude/settings.json" ]; then
     echo "✗ settings.json not created"
     exit 1
@@ -18,3 +24,49 @@ if ! grep -q "git@github.com:fx/cc.git" "$HOME/.claude/settings.json"; then
 fi
 
 echo "✓ Claude marketplace configured correctly"
+
+# Verify npm package installation
+# Helper function to run npm via mise
+run_npm() {
+    if command -v mise >/dev/null 2>&1; then
+        mise exec -- npm "$@"
+    else
+        npm "$@"
+    fi
+}
+
+# Check if npm is available
+if command -v mise >/dev/null 2>&1; then
+    if ! mise exec -- npm --version >/dev/null 2>&1; then
+        echo "⚠️  npm not available, skipping package verification"
+        exit 0
+    fi
+elif ! command -v npm >/dev/null 2>&1; then
+    echo "⚠️  npm not available, skipping package verification"
+    exit 0
+fi
+
+# Parse packages.yaml and verify each npm global package
+if command -v yq >/dev/null 2>&1 && [ -f "$HOME/.local/share/chezmoi/.chezmoidata/packages.yaml" ]; then
+    # Use yq to parse the YAML file
+    npm_packages=$(yq eval '.npm.global[]' "$HOME/.local/share/chezmoi/.chezmoidata/packages.yaml" 2>/dev/null || echo "")
+    if [ -n "$npm_packages" ]; then
+        while IFS= read -r package; do
+            if [ -n "$package" ]; then
+                # npm list can exit non-zero due to warnings, so check the output instead
+                if ! run_npm list -g "$package" 2>&1 | grep -qF "$package@"; then
+                    echo "✗ npm package $package not installed"
+                    exit 1
+                fi
+                echo "✓ npm package $package installed correctly"
+            fi
+        done <<< "$npm_packages"
+    fi
+else
+    # Fallback: Check known packages if yq is not available
+    if ! run_npm list -g @anthropic-ai/claude-code 2>&1 | grep -qF "@anthropic-ai/claude-code@"; then
+        echo "✗ @anthropic-ai/claude-code not installed"
+        exit 1
+    fi
+    echo "✓ @anthropic-ai/claude-code installed correctly"
+fi