diff --git a/.github/rulesets/main-protection.json b/.github/rulesets/main-protection.json
new file mode 100644
index 000000000..c00c76962
--- /dev/null
+++ b/.github/rulesets/main-protection.json
@@ -0,0 +1,42 @@
+{
+  "name": "ARStack Main - Pull Requests and Naming CI",
+  "target": "branch",
+  "enforcement": "active",
+  "conditions": {
+    "ref_name": {
+      "include": [
+        "refs/heads/main"
+      ],
+      "exclude": []
+    }
+  },
+  "rules": [
+    {
+      "type": "deletion"
+    },
+    {
+      "type": "non_fast_forward"
+    },
+    {
+      "type": "pull_request",
+      "parameters": {
+        "dismiss_stale_reviews_on_push": true,
+        "require_code_owner_review": false,
+        "require_last_push_approval": false,
+        "required_approving_review_count": 0,
+        "required_review_thread_resolution": true
+      }
+    },
+    {
+      "type": "required_status_checks",
+      "parameters": {
+        "strict_required_status_checks_policy": true,
+        "required_status_checks": [
+          {
+            "context": "tracked-tree-names"
+          }
+        ]
+      }
+    }
+  ]
+}
diff --git a/docs/MAINTAINER_MAIN_PROTECTION.md b/docs/MAINTAINER_MAIN_PROTECTION.md
new file mode 100644
index 000000000..164de098d
--- /dev/null
+++ b/docs/MAINTAINER_MAIN_PROTECTION.md
@@ -0,0 +1,27 @@
+# Protect the public `main` branch
+
+ARStack's public releases come from reviewed `main`. Keeping merges on PRs protects the working downloads, documentation and tested runtime.
+
+The recommended main ruleset is checked into the repository as [`.github/rulesets/main-protection.json`](../.github/rulesets/main-protection.json). It prevents branch deletion and force-pushes, requires a pull request, requires resolved review discussions, and requires the universal **Product Naming Guard / tracked-tree-names** check against the latest `main` revision.
+
+The approving-review count is **zero** for a solo-maintainer open-source repository: the PR and required automated check remain mandatory without requiring an outside reviewer for every documentation change. Runtime and installer changes should also show their relevant C++/Qt/package CI green before merge.
+
+## Activate (repository administrator)
+
+Using the [GitHub CLI](https://cli.github.com/) authenticated with repository administration permission:
+
+```bash
+bash scripts/apply_main_ruleset.sh --dry-run
+bash scripts/apply_main_ruleset.sh --apply
+```
+
+The script updates a ruleset of the same name or creates it once, then prints GitHub's resulting ruleset. Alternatively, go to **Settings → Rules → Rulesets → New branch ruleset** and apply the JSON equivalent.
+
+After activation, confirm:
+
+1. **Settings → Rules → Rulesets** lists `ARStack Main - Pull Requests and Naming CI` as active.
+2. A direct push to `main` is refused and new changes go through PRs.
+3. A PR without a successful `tracked-tree-names` check cannot merge.
+4. A PR built against an outdated `main` must update before merging.
+
+**Connector access:** The GitHub integration permits source, PR and CI changes but rejects branch-protection administration (HTTP 403). Merely storing this JSON does not turn GitHub protection on; it must be applied by an authorized administrator. Historical release tags and verified binaries are unaffected.
diff --git a/scripts/apply_main_ruleset.sh b/scripts/apply_main_ruleset.sh
new file mode 100644
index 000000000..3996d5e31
--- /dev/null
+++ b/scripts/apply_main_ruleset.sh
@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+# Apply the reviewed, repo-owned main ruleset using an administrator's GitHub CLI session.
+set -euo pipefail
+repo='masarray/arstack61850'
+name='ARStack Main - Pull Requests and Naming CI'
+root="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+manifest="$root/.github/rulesets/main-protection.json"
+python3 -m json.tool "$manifest" >/dev/null
+case "${1:---dry-run}" in
+  --dry-run)
+    echo "Ruleset validated. This command has not changed GitHub settings."
+    echo "To activate as a repository admin: bash scripts/apply_main_ruleset.sh --apply"
+    exit 0
+    ;;
+  --apply) ;;
+  *) echo 'Usage: bash scripts/apply_main_ruleset.sh [--dry-run|--apply]' >&2; exit 2;;
+esac
+command -v gh >/dev/null || { echo 'GitHub CLI is required: https://cli.github.com/' >&2; exit 1; }
+gh auth status >/dev/null
+existing="$(gh api "repos/$repo/rulesets" --jq '.[] | select(.name == "ARStack Main - Pull Requests and Naming CI") | .id' | head -n1)"
+if [ -n "$existing" ]; then
+  gh api --method PUT "repos/$repo/rulesets/$existing" --input "$manifest" >/dev/null
+  echo "Updated active main ruleset ID: $existing"
+else
+  gh api --method POST "repos/$repo/rulesets" --input "$manifest" >/dev/null
+  echo "Created active main ruleset."
+fi
+gh api "repos/$repo/rulesets" --jq '.[] | select(.name == "ARStack Main - Pull Requests and Naming CI") | {id,name,enforcement}'
+echo 'Confirm on GitHub: Settings > Rules > Rulesets'