diff --git a/libs/beacon/src/beacon/domains/warehouse/contribute.py b/libs/beacon/src/beacon/domains/warehouse/contribute.py
index 8f45987..c1b485f 100644
--- a/libs/beacon/src/beacon/domains/warehouse/contribute.py
+++ b/libs/beacon/src/beacon/domains/warehouse/contribute.py
@@ -12,6 +12,7 @@
 
 from beacon.domains.warehouse._tracked_paths import get_tracked_paths
 from beacon.domains.warehouse.preconditions import ensure_sync_ready
+from beacon.utils.paths import normalize_relative_path
 
 
 @dataclass
@@ -91,15 +92,16 @@ def contribute(
     tracked_paths = get_tracked_paths(warehouse_path, beacon_yaml)
 
     if paths is not None:
+        normalized_paths = [normalize_relative_path(p) for p in paths]
         tracked_set = set(tracked_paths)
-        untracked = [p for p in paths if p not in tracked_set]
+        untracked = [p for p in normalized_paths if p not in tracked_set]
         if untracked:
             raise ValueError(
                 f"The following paths are not tracked by beacon.yaml and cannot be committed: "
                 f"{', '.join(repr(p) for p in untracked)}"
             )
         # Use the caller-supplied paths (preserving their order), scoped within tracked_paths
-        commit_paths = list(paths)
+        commit_paths = normalized_paths
     else:
         commit_paths = tracked_paths
 
diff --git a/libs/beacon/src/beacon/utils/paths.py b/libs/beacon/src/beacon/utils/paths.py
new file mode 100644
index 0000000..c96dcdd
--- /dev/null
+++ b/libs/beacon/src/beacon/utils/paths.py
@@ -0,0 +1,28 @@
+"""Stateless path helpers with no domain knowledge."""
+
+import os
+from pathlib import Path
+
+
+def normalize_relative_path(path: str) -> str:
+    """Normalize a user-supplied relative path for membership checking.
+
+    * Converts to POSIX-style forward slashes.
+    * Removes leading './' segments.
+    * Collapses redundant separators (e.g. 'skills//foo' -> 'skills/foo').
+    * Rejects absolute paths and parent-directory traversal.
+
+    Raises:
+        ValueError: if the path is absolute or contains a '..' component.
+    """
+    p = Path(path)
+    if p.is_absolute():
+        raise ValueError(f"Absolute paths are not allowed: {path!r}")
+    parts = p.parts
+    if ".." in parts:
+        raise ValueError(f"Parent-directory traversal is not allowed: {path!r}")
+    # normpath removes './' and collapses redundant separators
+    normalized = os.path.normpath(path)
+    # Ensure POSIX-style forward slashes for cross-platform consistency
+    normalized = normalized.replace(os.sep, "/")
+    return normalized
diff --git a/libs/beacon/tests/unit/utils/test_paths.py b/libs/beacon/tests/unit/utils/test_paths.py
new file mode 100644
index 0000000..288ab64
--- /dev/null
+++ b/libs/beacon/tests/unit/utils/test_paths.py
@@ -0,0 +1,43 @@
+"""Unit tests for path normalization utilities."""
+
+import pytest
+from beacon.utils.paths import normalize_relative_path
+
+
+class TestNormalizeRelativePath:
+    """Test cases for normalize_relative_path (PER-184)."""
+
+    def test_plain_path_unchanged(self):
+        """A clean relative path passes through unchanged."""
+        assert normalize_relative_path("contexts/a.md") == "contexts/a.md"
+
+    def test_leading_dot_slash_stripped(self):
+        """Leading './' is removed."""
+        assert normalize_relative_path("./contexts/a.md") == "contexts/a.md"
+
+    def test_double_slash_collapsed(self):
+        """Redundant '//' separators are collapsed."""
+        assert normalize_relative_path("contexts//a.md") == "contexts/a.md"
+
+    def test_nested_dot_segments_collapsed(self):
+        """Interior '.' segments are collapsed."""
+        assert normalize_relative_path("contexts/./a.md") == "contexts/a.md"
+
+    def test_absolute_path_rejected(self):
+        """Absolute paths raise ValueError."""
+        with pytest.raises(ValueError, match="[Aa]bsolute"):
+            normalize_relative_path("/absolute/path.md")
+
+    def test_parent_traversal_rejected(self):
+        """Paths containing '..' raise ValueError."""
+        with pytest.raises(ValueError, match="[Pp]arent-directory"):
+            normalize_relative_path("../outside.md")
+
+    def test_parent_traversal_interior_rejected(self):
+        """A '..' component anywhere in the path is rejected."""
+        with pytest.raises(ValueError, match="[Pp]arent-directory"):
+            normalize_relative_path("contexts/../../../etc/passwd")
+
+    def test_dotdot_in_filename_not_rejected(self):
+        """A literal '..' inside a filename is not a traversal component."""
+        assert normalize_relative_path("contexts/foo..bar.md") == "contexts/foo..bar.md"
diff --git a/libs/beacon/tests/unit/warehouse/test_contribute.py b/libs/beacon/tests/unit/warehouse/test_contribute.py
index 5a82d24..66494f0 100644
--- a/libs/beacon/tests/unit/warehouse/test_contribute.py
+++ b/libs/beacon/tests/unit/warehouse/test_contribute.py
@@ -448,6 +448,80 @@ def test_contribute_paths_sequential_groups_leave_others_dirty(
         assert "commit b" in log.stdout
         assert "commit a" in log.stdout
 
+    def test_contribute_paths_leading_dot_slash(self, contrib_project_multi):
+        """Leading './' is normalized away before membership check."""
+        project, wh = contrib_project_multi
+        env = _git_env()
+
+        (wh / "contexts" / "a.md").write_text("# a modified\n")
+
+        result = contribute(
+            project,
+            message="commit with ./prefix",
+            push=False,
+            paths=("./contexts/a.md",),
+        )
+        assert result.status == "committed"
+
+        committed_files = subprocess.run(
+            ["git", "show", "--name-only", "--format=", "HEAD"],
+            cwd=wh,
+            env=env,
+            capture_output=True,
+            text=True,
+            check=True,
+        )
+        assert "contexts/a.md" in committed_files.stdout
+
+    def test_contribute_paths_double_slash(self, contrib_project_multi):
+        """Redundant '//' separators are collapsed."""
+        project, wh = contrib_project_multi
+        env = _git_env()
+
+        (wh / "contexts" / "a.md").write_text("# a modified\n")
+
+        result = contribute(
+            project,
+            message="commit with double slash",
+            push=False,
+            paths=("contexts//a.md",),
+        )
+        assert result.status == "committed"
+
+        committed_files = subprocess.run(
+            ["git", "show", "--name-only", "--format=", "HEAD"],
+            cwd=wh,
+            env=env,
+            capture_output=True,
+            text=True,
+            check=True,
+        )
+        assert "contexts/a.md" in committed_files.stdout
+
+    def test_contribute_paths_absolute_rejected(self, contrib_project_multi):
+        """Absolute paths raise ValueError."""
+        project, wh = contrib_project_multi
+        with pytest.raises(ValueError) as exc_info:
+            contribute(
+                project,
+                message="should fail",
+                push=False,
+                paths=("/absolute/path.md",),
+            )
+        assert "absolute" in str(exc_info.value).lower()
+
+    def test_contribute_paths_dotdot_rejected(self, contrib_project_multi):
+        """Paths with '..' raise ValueError."""
+        project, wh = contrib_project_multi
+        with pytest.raises(ValueError) as exc_info:
+            contribute(
+                project,
+                message="should fail",
+                push=False,
+                paths=("../outside.md",),
+            )
+        assert "parent-directory" in str(exc_info.value).lower()
+
 
 class TestDirtyOutsideScope:
     """Tests for PER-159: out-of-scope dirty file count in contribute."""