gnd: Fix manifest_dir to handle bare filenames like "subgraph.yaml"

When manifest_path is a bare filename without directory component,
Path::parent() returns Some("") (empty string), not None. The old code
only handled None with unwrap_or_else, causing canonicalize() to fail.

Add manifest_dir() helper that filters empty paths and use it
consistently across build, add, and migrations commands.

Author: lutter

gnd/src/commands/add.rs

@@ -94,7 +94,7 @@ pub async fn run_add(opt: AddOpt) -> Result<()> {
     let (abi, contract_name, start_block) = get_contract_info(&opt, &network).await?;
 
     // Get project directory
-    let project_dir = opt.manifest.parent().unwrap_or(Path::new("."));
+    let project_dir = crate::manifest::manifest_dir(&opt.manifest);
 
     // Create scaffold options for code generation
     let scaffold_options = ScaffoldOptions {

gnd/src/commands/build.rs

@@ -146,12 +146,7 @@ async fn build_subgraph(opt: &BuildOpt) -> Result<BuildResult> {
 
     // Load the manifest
     let manifest = load_manifest(&opt.manifest)?;
-    let source_dir = opt
-        .manifest
-        .parent()
-        .filter(|p| !p.as_os_str().is_empty())
-        .unwrap_or_else(|| Path::new("."))
-        .to_path_buf();
+    let source_dir = crate::manifest::manifest_dir(&opt.manifest).to_path_buf();
 
     // Validate manifest structure
     let manifest_errors = validate_manifest(&manifest, &source_dir);

gnd/src/manifest.rs

@@ -245,19 +245,48 @@ fn parse_abis(abis_value: Option<&serde_json::Value>) -> Vec<Abi> {
         .unwrap_or_default()
 }
 
+/// Get the directory containing a manifest file.
+///
+/// This handles the edge case where `manifest_path` is a bare filename
+/// like `"subgraph.yaml"` - in that case, `parent()` returns an empty
+/// path, so we fall back to `"."` (current directory).
+pub fn manifest_dir(manifest_path: &Path) -> &Path {
+    manifest_path
+        .parent()
+        .filter(|p| !p.as_os_str().is_empty())
+        .unwrap_or_else(|| Path::new("."))
+}
+
 /// Resolve a path relative to the manifest file.
 pub fn resolve_path(manifest: &Path, path: &str) -> PathBuf {
-    manifest
-        .parent()
-        .map(|p| p.join(path))
-        .unwrap_or_else(|| PathBuf::from(path))
+    manifest_dir(manifest).join(path)
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
     use tempfile::TempDir;
 
+    #[test]
+    fn test_manifest_dir_with_directory() {
+        let manifest = PathBuf::from("/home/user/project/subgraph.yaml");
+        assert_eq!(manifest_dir(&manifest), Path::new("/home/user/project"));
+    }
+
+    #[test]
+    fn test_manifest_dir_bare_filename() {
+        // When manifest_path is just "subgraph.yaml", parent() returns Some("")
+        // which is empty, so we should fall back to "."
+        let manifest = PathBuf::from("subgraph.yaml");
+        assert_eq!(manifest_dir(&manifest), Path::new("."));
+    }
+
+    #[test]
+    fn test_manifest_dir_relative_path() {
+        let manifest = PathBuf::from("./subgraph.yaml");
+        assert_eq!(manifest_dir(&manifest), Path::new("."));
+    }
+
     #[test]
     fn test_resolve_path() {
         let manifest = PathBuf::from("/home/user/project/subgraph.yaml");
@@ -266,6 +295,15 @@ mod tests {
         assert_eq!(resolved, PathBuf::from("/home/user/project/src/mapping.ts"));
     }
 
+    #[test]
+    fn test_resolve_path_bare_filename() {
+        // When manifest is just "subgraph.yaml", paths should resolve relative to "."
+        let manifest = PathBuf::from("subgraph.yaml");
+        let path = "src/mapping.ts";
+        let resolved = resolve_path(&manifest, path);
+        assert_eq!(resolved, PathBuf::from("./src/mapping.ts"));
+    }
+
     #[test]
     fn test_load_manifest_basic() {
         let temp_dir = TempDir::new().unwrap();

gnd/src/migrations/mod.rs

@@ -74,7 +74,7 @@ fn all_migrations() -> Vec<Box<dyn Migration>> {
 pub fn apply_migrations(manifest_path: &Path) -> Result<()> {
     step(Step::Load, "Apply migrations");
 
-    let source_dir = manifest_path.parent().unwrap_or_else(|| Path::new("."));
+    let source_dir = crate::manifest::manifest_dir(manifest_path);
 
     let ctx = MigrationContext {
         manifest_path,