fix(fermata): .botignore no longer stops project-root walk-up

Only .git, botignore.toml, and .botignore.toml define project boundaries.
A bare .botignore is a policy file, not a root marker.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/core/project.rs

@@ -1,7 +1,7 @@
 use std::path::{Path, PathBuf};
 
 /// Markers checked in priority order when walking up from a target path.
-const MARKERS: &[&str] = &["botignore.toml", ".botignore", ".git"];
+const MARKERS: &[&str] = &["botignore.toml", ".botignore.toml", ".git"];
 
 /// Walk upward from `target` (or its parent if `target` is a file) looking
 /// for the nearest project root. Roots are identified by the presence of

tests/core_project.rs

@@ -8,7 +8,7 @@ fn finds_botignore_toml_first() {
     let root = tmp.path();
     fs::create_dir_all(root.join("sub/deep")).unwrap();
     fs::write(root.join("botignore.toml"), "").unwrap();
-    fs::write(root.join(".botignore"), "").unwrap();
+    fs::write(root.join(".botignore.toml"), "").unwrap();
     fs::create_dir_all(root.join(".git")).unwrap();
 
     let target = root.join("sub/deep/file.rs");
@@ -19,7 +19,40 @@ fn finds_botignore_toml_first() {
 }
 
 #[test]
-fn falls_back_to_botignore() {
+fn finds_dot_botignore_toml() {
+    let tmp = TempDir::new().unwrap();
+    let root = tmp.path();
+    fs::create_dir_all(root.join("sub")).unwrap();
+    fs::write(root.join(".botignore.toml"), "").unwrap();
+
+    let target = root.join("sub/file.rs");
+    fs::write(&target, "").unwrap();
+
+    let found = find_project_root(&target).unwrap();
+    assert_eq!(found, root);
+}
+
+#[test]
+fn botignore_alone_does_not_stop_walk() {
+    // A bare .botignore is a policy file, not a project boundary.
+    // The walk should continue past it to find a real root marker.
+    let tmp = TempDir::new().unwrap();
+    let root = tmp.path();
+    fs::create_dir_all(root.join("a/b")).unwrap();
+    fs::create_dir_all(root.join(".git")).unwrap();
+    fs::write(root.join("a/.botignore"), "*.secret").unwrap();
+
+    let target = root.join("a/b/file.rs");
+    fs::write(&target, "").unwrap();
+
+    // Should find root (with .git), NOT root/a (with .botignore)
+    let found = find_project_root(&target).unwrap();
+    assert_eq!(found, root);
+}
+
+#[test]
+fn botignore_only_returns_none() {
+    // If only .botignore exists with no real root marker, no project root is found.
     let tmp = TempDir::new().unwrap();
     let root = tmp.path();
     fs::create_dir_all(root.join("sub")).unwrap();
@@ -28,8 +61,8 @@ fn falls_back_to_botignore() {
     let target = root.join("sub/file.rs");
     fs::write(&target, "").unwrap();
 
-    let found = find_project_root(&target).unwrap();
-    assert_eq!(found, root);
+    // .botignore alone should NOT define a project root
+    assert!(find_project_root(&target).is_none());
 }
 
 #[test]
@@ -59,7 +92,7 @@ fn walks_up_from_file_path_not_cwd() {
     let tmp = TempDir::new().unwrap();
     let root = tmp.path();
     fs::create_dir_all(root.join("a/b/c")).unwrap();
-    fs::write(root.join("a/.botignore"), "").unwrap();
+    fs::write(root.join("a/botignore.toml"), "").unwrap();
 
     let target = root.join("a/b/c/file.rs");
     fs::write(&target, "").unwrap();