diff --git a/code_review_graph/daemon.py b/code_review_graph/daemon.py
index 4675b155..0e3e943c 100644
--- a/code_review_graph/daemon.py
+++ b/code_review_graph/daemon.py
@@ -130,9 +130,9 @@ def load_config(path: Path | None = None) -> DaemonConfig:
             logger.warning("Skipping repo %s — directory does not exist", repo_path)
             continue
 
-        if not (repo_path / ".git").exists() and not (repo_path / ".code-review-graph").exists():
+        if not (repo_path / ".git").exists() and not (repo_path / ".svn").exists() and not (repo_path / ".code-review-graph").exists():
             logger.warning(
-                "Skipping repo %s — no .git or .code-review-graph directory found",
+                "Skipping repo %s — no .git, .svn, or .code-review-graph directory found",
                 repo_path,
             )
             continue
@@ -222,8 +222,8 @@ def add_repo_to_config(
     if not resolved.is_dir():
         raise ValueError(f"Not a directory: {resolved}")
 
-    if not (resolved / ".git").exists() and not (resolved / ".code-review-graph").exists():
-        raise ValueError(f"No .git or .code-review-graph directory in {resolved}")
+    if not (resolved / ".git").exists() and not (resolved / ".svn").exists() and not (resolved / ".code-review-graph").exists():
+        raise ValueError(f"No .git, .svn, or .code-review-graph directory in {resolved}")
 
     effective_alias = alias or resolved.name
 
diff --git a/code_review_graph/registry.py b/code_review_graph/registry.py
index b5e6d01c..f7a793d9 100644
--- a/code_review_graph/registry.py
+++ b/code_review_graph/registry.py
@@ -76,10 +76,10 @@ def register(
         resolved = Path(path).resolve()
         if not resolved.is_dir():
             raise ValueError(f"Path is not a directory: {resolved}")
-        if not (resolved / ".git").exists() and not (resolved / ".code-review-graph").exists():
+        if not (resolved / ".git").exists() and not (resolved / ".svn").exists() and not (resolved / ".code-review-graph").exists():
             raise ValueError(
                 f"Path does not look like a repository "
-                f"(no .git or .code-review-graph): {resolved}"
+                f"(no .git, .svn, or .code-review-graph): {resolved}"
             )
 
         with self._lock:
diff --git a/code_review_graph/tools/_common.py b/code_review_graph/tools/_common.py
index fd206a9b..fca6d38c 100644
--- a/code_review_graph/tools/_common.py
+++ b/code_review_graph/tools/_common.py
@@ -61,19 +61,25 @@ def _error_response(
 def _validate_repo_root(path: "Path | str") -> Path:
     """Validate that a path is a plausible project root.
 
-    Ensures the path is an existing directory that contains a ``.git``
-    or ``.code-review-graph`` directory, preventing arbitrary file-system
-    traversal via the ``repo_root`` parameter.
+    Ensures the path is an existing directory that contains a ``.git``,
+    ``.svn``, or ``.code-review-graph`` directory, preventing arbitrary
+    file-system traversal via the ``repo_root`` parameter.
     """
     resolved = Path(path).resolve()
     if not resolved.is_dir():
         raise ValueError(
             f"repo_root is not an existing directory: {resolved}"
         )
-    if not (resolved / ".git").exists() and not (resolved / ".code-review-graph").exists():
+    has_vcs = (
+        (resolved / ".git").exists()
+        or (resolved / ".svn").exists()
+        or (resolved / ".code-review-graph").exists()
+    )
+    if not has_vcs:
         raise ValueError(
-            f"repo_root does not look like a project root (no .git or "
-            f".code-review-graph directory found): {resolved}"
+            f"repo_root does not look like a project root "
+            f"(no .git, .svn, or .code-review-graph directory found): "
+            f"{resolved}"
         )
     return resolved