diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 96f333c..ecf0100 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -56,3 +56,47 @@ jobs:
         with:
           scandir: "."
           ignore_paths: "collections .github"
+
+  # --- macOS jobs --------------------------------------------------------
+  #
+  # Standard GitHub-hosted macos-26 runners are Apple Silicon (M1, 3 CPU,
+  # 7 GB RAM, 14 GB disk) and free for public repos. These two jobs catch
+  # platform-specific bugs that the Ubuntu lint jobs cannot see.
+
+  macos-check:
+    name: macos-check (syntax + asserts)
+    runs-on: macos-26
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Ansible via Homebrew
+        run: brew install ansible
+      - name: Install Ansible Galaxy collections
+        run: ansible-galaxy collection install -r requirements.yml
+      - name: ansible-playbook --syntax-check
+        run: ansible-playbook -i inventory/localhost.yml playbook.yml --syntax-check
+      - name: Run preflight asserts only
+        # --tags always pulls just the pre_tasks block (macOS / arm64 /
+        # Sequoia-or-later asserts). Proves the playbook can boot on a
+        # real Apple Silicon mac without doing any installs.
+        run: ansible-playbook -i inventory/localhost.yml playbook.yml --tags always
+
+  macos-homebrew:
+    name: macos-homebrew (install package set)
+    runs-on: macos-26
+    timeout-minutes: 25
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Ansible via Homebrew
+        run: brew install ansible
+      - name: Install Ansible Galaxy collections
+        run: ansible-galaxy collection install -r requirements.yml
+      - name: Run system + homebrew roles
+        # We stop here on purpose: the kubernetes role wants to launch
+        # Docker Desktop, which is not viable inside a CI runner. The
+        # homebrew install path is the high-leverage check for catching
+        # typo'd brew formulas / casks before a user hits them.
+        run: |
+          ansible-playbook -i inventory/localhost.yml playbook.yml \
+            --tags 'always,system,homebrew' \
+            --diff
diff --git a/ansible.cfg b/ansible.cfg
index 795a6ff..69b675f 100644
--- a/ansible.cfg
+++ b/ansible.cfg
@@ -1,14 +1,20 @@
 [defaults]
 inventory             = inventory/localhost.yml
 roles_path            = roles
-collections_paths     = ./collections:~/.ansible/collections
+collections_path      = ./collections:~/.ansible/collections
 host_key_checking     = False
 nocows                = True
-stdout_callback       = yaml
+# Use the in-tree default callback (community.general.yaml was
+# removed in community.general v12; modern Ansible wants the
+# `result_format` knob on ansible.builtin.default instead).
+stdout_callback       = ansible.builtin.default
 display_skipped_hosts = False
 retry_files_enabled   = False
 interpreter_python    = auto_silent
 
+[callback_default]
+result_format = yaml
+
 [inventory]
 enable_plugins = yaml, ini, auto
 
diff --git a/playbook.yml b/playbook.yml
index 7f5b880..82fc018 100644
--- a/playbook.yml
+++ b/playbook.yml
@@ -44,21 +44,23 @@
       tags: [always]
 
   roles:
-    # Base path -- everyone gets these in order.
+    # Base path -- everyone gets these in order. Each role also
+    # gets a tag of its own name so CI can run a subset cleanly
+    # (e.g. --tags system,homebrew for the macOS install test).
     - role: system
-      tags: [base]
+      tags: [base, system]
     - role: homebrew
-      tags: [base]
+      tags: [base, homebrew]
     - role: kubernetes
-      tags: [base]
+      tags: [base, kubernetes]
     - role: llmkube_core
-      tags: [base]
+      tags: [base, llmkube_core]
     - role: model_starter
-      tags: [base]
+      tags: [base, model_starter]
     - role: developer_tools
-      tags: [base]
+      tags: [base, developer_tools]
     - role: opencode
-      tags: [base]
+      tags: [base, opencode]
 
     # Opt-in -- only when --tags includes the matching tag.
     - role: carnice