Enable support for relative paths and symlinks

Fuser/compose_end_to_end.py

@@ -84,6 +84,7 @@ def _load_kernels_from_summary(summary_path: Path) -> list[KernelItem]:
     if not isinstance(data, list):
         raise SystemExit("kernels summary must be a JSON array (from dispatch step)")
     items: list[KernelItem] = []
+    summary_dir = summary_path.parent
     for it in data:
         if not isinstance(it, dict):
             continue
@@ -95,6 +96,9 @@ def _load_kernels_from_summary(summary_path: Path) -> list[KernelItem]:
         if not sid or not kpath_str:
             continue
         kpath = Path(kpath_str)
+        # If path is relative, resolve it relative to summary.json location
+        if not kpath.is_absolute():
+            kpath = summary_dir / kpath
         if not kpath.is_file():
             continue
         code = _read_text(kpath)

Fuser/paths.py

@@ -25,14 +25,14 @@ def ensure_abs_regular_file(p: str | Path) -> Path:
     if not path.is_absolute():
         raise PathSafetyError(f"problem path must be absolute: {path}")
     try:
-        st = path.lstat()
+        # Resolve symlinks to get the real path
+        resolved_path = path.resolve()
+        st = resolved_path.stat()
     except FileNotFoundError:
         raise PathSafetyError(f"problem path does not exist: {path}")
-    if stat.S_ISLNK(st.st_mode):
-        raise PathSafetyError(f"problem path must not be a symlink: {path}")
     if not stat.S_ISREG(st.st_mode):
         raise PathSafetyError(f"problem path must be a regular file: {path}")
-    return path
+    return resolved_path
 
 
 def make_run_dirs(base: Path, run_id: str) -> dict[str, Path]: