test(docs): guard main-first contributor PR base policy

tests/docs_pr_base_branch_consistency.rs

@@ -0,0 +1,31 @@
+use std::fs;
+use std::path::Path;
+
+fn read_repo_file(path: &str) -> String {
+    let repo_root = Path::new(env!("CARGO_MANIFEST_DIR"));
+    fs::read_to_string(repo_root.join(path))
+        .unwrap_or_else(|err| panic!("failed to read {path}: {err}"))
+}
+
+#[test]
+fn contributor_docs_use_main_as_default_pr_base_branch() {
+    let contributing = read_repo_file("CONTRIBUTING.md");
+    let pr_workflow = read_repo_file("docs/pr-workflow.md");
+
+    assert!(
+        contributing
+            .contains("Open a PR against `main` using the PR template (`dev` is used only when maintainers explicitly request integration batching)"),
+        "CONTRIBUTING.md must set main as the default contributor PR base"
+    );
+
+    assert!(
+        pr_workflow
+            .contains("Normal contributor PR base is `main` by default; use `dev` only when maintainers explicitly request integration batching."),
+        "docs/pr-workflow.md must match the main-first contributor PR base policy"
+    );
+
+    assert!(
+        !contributing.contains("Open a PR against `dev` using the PR template"),
+        "CONTRIBUTING.md still contains stale dev-first PR guidance"
+    );
+}