feat: Add kubeconfig refresh script and fix Ansible Finalize to use public IP

- scripts/refresh-kubeconfig.sh fetches a fresh kubeconfig from CP1
- Ansible site.yml Finalize step now uses public IP instead of Tailscale
  hostname for the kubeconfig server address
- Updated AGENTS.md with kubeconfig refresh instructions

AGENTS.md

@@ -66,6 +66,13 @@ Repository guide for agentic contributors working in this repo.
 - Prefer validating the exact directory you edited, not the whole repo, unless the change is cross-cutting.
 - For Flux changes, verify the relevant `Kustomization`/`HelmRelease`/`ExternalSecret` manifests render cleanly before committing.
 
+### Kubeconfig refresh
+
+After a full cluster rebuild, the kubeconfig goes stale (new certs, new IPs). Refresh it with:
+- `scripts/refresh-kubeconfig.sh <cp1-public-ip>` (preferred)
+- Or manually: `ssh -i ~/.ssh/infra root@<cp1-ip> "cat /etc/rancher/k3s/k3s.yaml" | sed 's/127.0.0.1/<cp1-ip>/g' > outputs/kubeconfig`
+- The Ansible `site.yml` Finalize step also rewrites the server address to the public IP during bootstrap.
+
 ## Code Style
 
 ### General

ansible/site.yml

@@ -134,7 +134,7 @@
   tasks:
     - name: Update kubeconfig server address
       command: |
-        sed -i 's/127.0.0.1/{{ groups["control_plane"][0] }}.{{ tailscale_tailnet }}/g' ../outputs/kubeconfig
+        sed -i 's/127.0.0.1/{{ hostvars[groups["control_plane"][0]]["ansible_host"] }}/g' ../outputs/kubeconfig
       changed_when: true
 
     - name: Display success message

scripts/refresh-kubeconfig.sh

@@ -0,0 +1,33 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+REPO_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"
+KUBECONFIG_PATH="$REPO_ROOT/outputs/kubeconfig"
+SSH_KEY="${SSH_KEY:-$HOME/.ssh/infra}"
+
+CP1_PUBLIC_IP="${1:-}"
+
+if [ -z "$CP1_PUBLIC_IP" ]; then
+    if [ -f "$REPO_ROOT/ansible/inventory.ini" ]; then
+        CP1_PUBLIC_IP=$(grep -A2 '\[control_plane\]' "$REPO_ROOT/ansible/inventory.ini" | grep -oP '\d+\.\d+\.\d+\.\d+' | head -1)
+    fi
+fi
+
+if [ -z "$CP1_PUBLIC_IP" ]; then
+    echo "Usage: $0 <control-plane-1-public-ip>"
+    echo "   Or ensure ansible/inventory.ini exists with control plane IPs."
+    exit 1
+fi
+
+echo "Fetching kubeconfig from $CP1_PUBLIC_IP ..."
+ssh -i "$SSH_KEY" \
+    -o StrictHostKeyChecking=no \
+    -o UserKnownHostsFile=/dev/null \
+    "root@$CP1_PUBLIC_IP" "cat /etc/rancher/k3s/k3s.yaml" \
+    | sed "s/127.0.0.1/$CP1_PUBLIC_IP/g" \
+    > "$KUBECONFIG_PATH"
+
+chmod 600 "$KUBECONFIG_PATH"
+echo "Kubeconfig saved to $KUBECONFIG_PATH"
+echo "Run: export KUBECONFIG=$KUBECONFIG_PATH"