feat(images): provide MDN MCP server via managed settings

.devcontainer/claude-sandbox/init-firewall.sh

@@ -69,7 +69,8 @@ for domain in \
     "update.code.visualstudio.com" \
     "auth.openai.com" \
     "api.openai.com" \
-    "chatgpt.com"; do
+    "chatgpt.com" \
+    "mcp.mdn.mozilla.net"; do
     echo "Resolving $domain..."
     ips=$(dig +noall +answer A "$domain" | awk '$4 == "A" {print $5}')
     if [ -z "$ips" ]; then

.github/workflows/build-claude-code.yml

@@ -75,19 +75,19 @@ jobs:
       matrix:
         include:
           - image-suffix: claude-code
-            verify-command: "bun --version || true && claude --version && mise --version && zsh --version && gh --version && gh stack --version && rtk --version && ralphex --version && test -x /usr/local/bin/patch-playwright-mcp && test -r /etc/claude-code/managed-settings.json && jq -r '.hooks.SessionStart[0].hooks[0].command' /etc/claude-code/managed-settings.json | grep -qx /usr/local/bin/patch-playwright-mcp && printenv AGENT_BROWSER_EXECUTABLE_PATH | grep -qx /usr/bin/chromium && zsh -ic 'typeset -p ZSH_THEME' | grep -q powerlevel10k/powerlevel10k && stat -c %U /home/node/.local/share | grep -qx node && stat -c %U /home/node/.config/gh | grep -qx node"
+            verify-command: "bun --version || true && claude --version && mise --version && zsh --version && gh --version && gh stack --version && rtk --version && ralphex --version && test -x /usr/local/bin/patch-playwright-mcp && test -r /etc/claude-code/managed-settings.json && jq -r '.hooks.SessionStart[0].hooks[0].command' /etc/claude-code/managed-settings.json | grep -qx /usr/local/bin/patch-playwright-mcp && jq -r '.managedMcpServers.mdn.url' /etc/claude-code/managed-settings.json | grep -qx https://mcp.mdn.mozilla.net/ && printenv AGENT_BROWSER_EXECUTABLE_PATH | grep -qx /usr/bin/chromium && zsh -ic 'typeset -p ZSH_THEME' | grep -q powerlevel10k/powerlevel10k && stat -c %U /home/node/.local/share | grep -qx node && stat -c %U /home/node/.config/gh | grep -qx node"
             runner: ubuntu-24.04
             arch: amd64
           - image-suffix: claude-code
-            verify-command: "bun --version || true && claude --version && mise --version && zsh --version && gh --version && gh stack --version && rtk --version && ralphex --version && test -x /usr/local/bin/patch-playwright-mcp && test -r /etc/claude-code/managed-settings.json && jq -r '.hooks.SessionStart[0].hooks[0].command' /etc/claude-code/managed-settings.json | grep -qx /usr/local/bin/patch-playwright-mcp && printenv AGENT_BROWSER_EXECUTABLE_PATH | grep -qx /usr/bin/chromium && zsh -ic 'typeset -p ZSH_THEME' | grep -q powerlevel10k/powerlevel10k && stat -c %U /home/node/.local/share | grep -qx node && stat -c %U /home/node/.config/gh | grep -qx node"
+            verify-command: "bun --version || true && claude --version && mise --version && zsh --version && gh --version && gh stack --version && rtk --version && ralphex --version && test -x /usr/local/bin/patch-playwright-mcp && test -r /etc/claude-code/managed-settings.json && jq -r '.hooks.SessionStart[0].hooks[0].command' /etc/claude-code/managed-settings.json | grep -qx /usr/local/bin/patch-playwright-mcp && jq -r '.managedMcpServers.mdn.url' /etc/claude-code/managed-settings.json | grep -qx https://mcp.mdn.mozilla.net/ && printenv AGENT_BROWSER_EXECUTABLE_PATH | grep -qx /usr/bin/chromium && zsh -ic 'typeset -p ZSH_THEME' | grep -q powerlevel10k/powerlevel10k && stat -c %U /home/node/.local/share | grep -qx node && stat -c %U /home/node/.config/gh | grep -qx node"
             runner: ubuntu-24.04-arm
             arch: arm64
           - image-suffix: claude-code-sandbox
-            verify-command: "claude --version && mise --version && zsh --version && gh --version && gh stack --version && which iptables && rtk --version && ralphex --version && test -x /usr/local/bin/patch-playwright-mcp && test -r /etc/claude-code/managed-settings.json && jq -r '.hooks.SessionStart[0].hooks[0].command' /etc/claude-code/managed-settings.json | grep -qx /usr/local/bin/patch-playwright-mcp && zsh -ic 'typeset -p ZSH_THEME' | grep -q powerlevel10k/powerlevel10k && stat -c %U /home/node/.local/share | grep -qx node && stat -c %U /home/node/.config/gh | grep -qx node"
+            verify-command: "claude --version && mise --version && zsh --version && gh --version && gh stack --version && which iptables && rtk --version && ralphex --version && test -x /usr/local/bin/patch-playwright-mcp && test -r /etc/claude-code/managed-settings.json && jq -r '.hooks.SessionStart[0].hooks[0].command' /etc/claude-code/managed-settings.json | grep -qx /usr/local/bin/patch-playwright-mcp && jq -r '.managedMcpServers.mdn.url' /etc/claude-code/managed-settings.json | grep -qx https://mcp.mdn.mozilla.net/ && zsh -ic 'typeset -p ZSH_THEME' | grep -q powerlevel10k/powerlevel10k && stat -c %U /home/node/.local/share | grep -qx node && stat -c %U /home/node/.config/gh | grep -qx node"
             runner: ubuntu-24.04
             arch: amd64
           - image-suffix: claude-code-sandbox
-            verify-command: "claude --version && mise --version && zsh --version && gh --version && gh stack --version && which iptables && rtk --version && ralphex --version && test -x /usr/local/bin/patch-playwright-mcp && test -r /etc/claude-code/managed-settings.json && jq -r '.hooks.SessionStart[0].hooks[0].command' /etc/claude-code/managed-settings.json | grep -qx /usr/local/bin/patch-playwright-mcp && zsh -ic 'typeset -p ZSH_THEME' | grep -q powerlevel10k/powerlevel10k && stat -c %U /home/node/.local/share | grep -qx node && stat -c %U /home/node/.config/gh | grep -qx node"
+            verify-command: "claude --version && mise --version && zsh --version && gh --version && gh stack --version && which iptables && rtk --version && ralphex --version && test -x /usr/local/bin/patch-playwright-mcp && test -r /etc/claude-code/managed-settings.json && jq -r '.hooks.SessionStart[0].hooks[0].command' /etc/claude-code/managed-settings.json | grep -qx /usr/local/bin/patch-playwright-mcp && jq -r '.managedMcpServers.mdn.url' /etc/claude-code/managed-settings.json | grep -qx https://mcp.mdn.mozilla.net/ && zsh -ic 'typeset -p ZSH_THEME' | grep -q powerlevel10k/powerlevel10k && stat -c %U /home/node/.local/share | grep -qx node && stat -c %U /home/node/.config/gh | grep -qx node"
             runner: ubuntu-24.04-arm
             arch: arm64
     runs-on: ${{ matrix.runner }}

.github/workflows/build-ralphex-fe.yml

@@ -7,6 +7,7 @@ on:
     paths:
       - 'ralphex-fe/Dockerfile'
       - 'ralphex-fe/*.sh'
+      - 'ralphex-fe/managed-settings.json'
   workflow_dispatch:
 
 permissions:
@@ -107,5 +108,7 @@ jobs:
             test -f /srv/init.sh &&
             chromium --no-sandbox --version &&
             test -x /usr/bin/chromium &&
+            test -r /etc/claude-code/managed-settings.json &&
+            jq -r '.managedMcpServers.mdn.url' /etc/claude-code/managed-settings.json | grep -qx https://mcp.mdn.mozilla.net/ &&
             echo 'All checks passed'
           "

.github/workflows/ci.yml

@@ -117,12 +117,12 @@ jobs:
             add_image "claude-code" \
               "claude-code/.devcontainer" \
               "claude-code/.devcontainer/Dockerfile" \
-              "bun --version || true && claude --version && mise --version && zsh --version && gh --version && gh stack --version && rtk --version && ralphex --version && test -x /usr/local/bin/patch-playwright-mcp && test -r /etc/claude-code/managed-settings.json && jq -r '.hooks.SessionStart[0].hooks[0].command' /etc/claude-code/managed-settings.json | grep -qx /usr/local/bin/patch-playwright-mcp && printenv AGENT_BROWSER_EXECUTABLE_PATH | grep -qx /usr/bin/chromium && zsh -ic 'typeset -p ZSH_THEME' | grep -q powerlevel10k/powerlevel10k && stat -c %U /home/node/.local/share | grep -qx node && stat -c %U /home/node/.config/gh | grep -qx node" \
+              "bun --version || true && claude --version && mise --version && zsh --version && gh --version && gh stack --version && rtk --version && ralphex --version && test -x /usr/local/bin/patch-playwright-mcp && test -r /etc/claude-code/managed-settings.json && jq -r '.hooks.SessionStart[0].hooks[0].command' /etc/claude-code/managed-settings.json | grep -qx /usr/local/bin/patch-playwright-mcp && jq -r '.managedMcpServers.mdn.url' /etc/claude-code/managed-settings.json | grep -qx https://mcp.mdn.mozilla.net/ && printenv AGENT_BROWSER_EXECUTABLE_PATH | grep -qx /usr/bin/chromium && zsh -ic 'typeset -p ZSH_THEME' | grep -q powerlevel10k/powerlevel10k && stat -c %U /home/node/.local/share | grep -qx node && stat -c %U /home/node/.config/gh | grep -qx node" \
               "default"
             add_image "claude-code-sandbox" \
               "claude-code/.devcontainer" \
               "claude-code/.devcontainer/Dockerfile" \
-              "claude --version && mise --version && zsh --version && gh --version && gh stack --version && which iptables && rtk --version && ralphex --version && test -x /usr/local/bin/patch-playwright-mcp && test -r /etc/claude-code/managed-settings.json && jq -r '.hooks.SessionStart[0].hooks[0].command' /etc/claude-code/managed-settings.json | grep -qx /usr/local/bin/patch-playwright-mcp && zsh -ic 'typeset -p ZSH_THEME' | grep -q powerlevel10k/powerlevel10k && stat -c %U /home/node/.local/share | grep -qx node && stat -c %U /home/node/.config/gh | grep -qx node" \
+              "claude --version && mise --version && zsh --version && gh --version && gh stack --version && which iptables && rtk --version && ralphex --version && test -x /usr/local/bin/patch-playwright-mcp && test -r /etc/claude-code/managed-settings.json && jq -r '.hooks.SessionStart[0].hooks[0].command' /etc/claude-code/managed-settings.json | grep -qx /usr/local/bin/patch-playwright-mcp && jq -r '.managedMcpServers.mdn.url' /etc/claude-code/managed-settings.json | grep -qx https://mcp.mdn.mozilla.net/ && zsh -ic 'typeset -p ZSH_THEME' | grep -q powerlevel10k/powerlevel10k && stat -c %U /home/node/.local/share | grep -qx node && stat -c %U /home/node/.config/gh | grep -qx node" \
               "sandbox"
           fi
 
@@ -144,7 +144,7 @@ jobs:
             add_image "ralphex-fe" \
               "ralphex-fe" \
               "ralphex-fe/Dockerfile" \
-              "bun --version && hugo version && go version && docker --version && /srv/ralphex --version && rtk --version"
+              "bun --version && hugo version && go version && docker --version && /srv/ralphex --version && rtk --version && test -r /etc/claude-code/managed-settings.json && jq -r '.managedMcpServers.mdn.url' /etc/claude-code/managed-settings.json | grep -qx https://mcp.mdn.mozilla.net/"
           fi
 
           if [ "$INCLUDES" = "[]" ]; then

claude-code/.devcontainer/Dockerfile

@@ -186,7 +186,8 @@ COPY --chmod=0755 patch-playwright-mcp.sh /usr/local/bin/patch-playwright-mcp
 
 # ── Claude Code managed settings ─────────────────────────────────────────────
 # Image-policy settings at the Linux managed location (highest precedence, outside
-# any volume mount). Wires patch-playwright-mcp as a SessionStart hook. See #98, #101.
+# any volume mount). Wires patch-playwright-mcp as a SessionStart hook (#98, #101)
+# and provides the MDN MCP server. managedMcpServers needs Claude Code >= 2.1.259.
 #
 # /etc/claude-code is created explicitly: BuildKit applies COPY --chmod to parent
 # dirs it auto-creates, leaving 0644 — not traversable.

claude-code/.devcontainer/managed-settings.json

@@ -10,5 +10,14 @@
         ]
       }
     ]
+  },
+  "managedMcpServers": {
+    "mdn": {
+      "type": "http",
+      "url": "https://mcp.mdn.mozilla.net/",
+      "headers": {
+        "X-Moz-1st-Party-Data-Opt-Out": "1"
+      }
+    }
   }
 }

claude-code/README.md

@@ -29,6 +29,12 @@ Projects consume these pre-built images and control their own tool versions via
 
 **Sandbox-only:** iptables, ipset, iproute2, dnsutils, aggregate, firewall sudo rule
 
+### MDN MCP server
+
+The image provides Mozilla's [MDN MCP server](https://developer.mozilla.org/en-US/mcp) (web platform docs and browser compatibility data) to every session through `managedMcpServers` in `/etc/claude-code/managed-settings.json` — no per-project setup. It sends `X-Moz-1st-Party-Data-Opt-Out: 1`, Mozilla's documented opt-out from the query logging they do while the server is experimental.
+
+Requires Claude Code >= 2.1.259; earlier clients ignore the key. `claude mcp remove` refuses it, but each developer can turn it off for themselves in `/mcp` under **Managed MCPs**. Sandbox users must allowlist `mcp.mdn.mozilla.net` in their firewall script.
+
 ## Multi-platform Support
 
 Both variants are built for:
@@ -125,7 +131,7 @@ To remove a plugin in your project, delete its entry from the local `init-plugin
 
 Default-deny iptables firewall. The image provides the packages and sudo rule; the project provides this script via bind mount. Customize the domain allowlist for your project.
 
-See the [repo's own sandbox firewall script](../.devcontainer/claude-sandbox/init-firewall.sh) for a complete example. The script should: preserve Docker internal DNS rules, allow DNS/SSH/localhost, fetch GitHub IP ranges via `curl -s https://api.github.com/meta`, resolve additional allowed domains (npm, Anthropic API, VS Code marketplace, etc.) via `dig`, set default DROP policies, allow established connections and the ipset allowlist, then verify by confirming `example.com` is blocked and `api.github.com` is reachable.
+See the [repo's own sandbox firewall script](../.devcontainer/claude-sandbox/init-firewall.sh) for a complete example. The script should: preserve Docker internal DNS rules, allow DNS/SSH/localhost, fetch GitHub IP ranges via `curl -s https://api.github.com/meta`, resolve additional allowed domains (npm, Anthropic API, VS Code marketplace, `mcp.mdn.mozilla.net` for the MDN MCP server, etc.) via `dig`, set default DROP policies, allow established connections and the ipset allowlist, then verify by confirming `example.com` is blocked and `api.github.com` is reachable.
 
 Mark as executable and ensure git tracks the executable bit:
 

ralphex-fe/Dockerfile

@@ -168,6 +168,12 @@ ARG CLAUDE_CODE_VERSION=2.1.280
 RUN --mount=type=cache,target=/root/.npm \
     npm install -g @anthropic-ai/claude-code@${CLAUDE_CODE_VERSION}
 
+# ── Claude Code managed settings ─────────────────────────────────────────────
+# Provides the MDN MCP server to every session, including `claude -p` runs.
+# managedMcpServers needs Claude Code >= 2.1.259; earlier clients ignore it.
+RUN mkdir -p /etc/claude-code
+COPY --chown=root:root --chmod=0644 managed-settings.json /etc/claude-code/managed-settings.json
+
 # ── Bun ──────────────────────────────────────────────────────────────────────
 ENV BUN_INSTALL=/usr/local/bun
 ENV PATH="$BUN_INSTALL/bin:$PATH"

ralphex-fe/README.md

@@ -11,20 +11,26 @@ This is a standalone image, not a devcontainer.
 | Tool | Version |
 |------|---------|
 | Node.js | 24 (from base image) |
-| Bun | 1.3.9 |
-| Hugo Extended | 0.156.0 |
+| Bun | 1.4.2 |
+| Hugo Extended | 0.166.0 |
 | Go | for Hugo Modules |
 | Python 3 | system |
 | Playwright + Chromium | native Debian |
-| Claude Code CLI | 2.1.216 (pinned) |
-| RTK | 0.43.0 (pinned) |
-| Ralphex | 1.6.0 (pinned) |
-| Git, ripgrep, jq, curl, wget | system |
+| Claude Code CLI | 2.1.280 (pinned) |
+| RTK | 0.49.0 (pinned) |
+| Ralphex | 1.7.0 (pinned) |
+| Git, ripgrep, jq, curl | system |
 
 All pinned versions live as `ARG`s in the Dockerfile and are kept current by Renovate — see
 [Automatic Rebuilds](#automatic-rebuilds). This image has no `mise`, so its Bun and Hugo are
 image-level versions rather than per-project ones; Renovate tracks them like everything else.
 
+### MDN MCP server
+
+The image provides Mozilla's [MDN MCP server](https://developer.mozilla.org/en-US/mcp) (web platform docs and browser compatibility data) through `managedMcpServers` in `/etc/claude-code/managed-settings.json`. Ralphex drives Claude non-interactively; a local managed settings file is read at session start, so `claude -p` runs get it too — the unattended runs where a hallucinated DOM or CSS API would otherwise land in a commit unreviewed.
+
+It sends `X-Moz-1st-Party-Data-Opt-Out: 1`, Mozilla's documented opt-out from the query logging they do while the server is experimental. Requires Claude Code >= 2.1.259; earlier clients ignore the key.
+
 ## Usage
 
 ### Via ralphex docker-wrapper
@@ -69,7 +75,7 @@ This image is built for multiple architectures:
 ## Image Tags
 
 - `latest` — most recent build
-- `bun{VERSION}-hugo{VERSION}` — version-specific tag (e.g., `bun1.3.9-hugo0.156.0`)
+- `bun{VERSION}-hugo{VERSION}` — version-specific tag (e.g., `bun1.4.2-hugo0.166.0`)
 
 Note: this image deviates from the standalone convention of a single primary version tag because it bundles multiple independently-versioned tools.
 

ralphex-fe/managed-settings.json

@@ -0,0 +1,11 @@
+{
+  "managedMcpServers": {
+    "mdn": {
+      "type": "http",
+      "url": "https://mcp.mdn.mozilla.net/",
+      "headers": {
+        "X-Moz-1st-Party-Data-Opt-Out": "1"
+      }
+    }
+  }
+}