diff --git a/src/context_engine/project_commands.py b/src/context_engine/project_commands.py
index caf5d94..1ccb397 100644
--- a/src/context_engine/project_commands.py
+++ b/src/context_engine/project_commands.py
@@ -232,6 +232,12 @@ def remove_preference(project_dir: str, key: str) -> bool:
     # CCE local cache and per-machine files
     (".cce/", "CCE local cache (per-machine, not for version control)"),
     (".claude/settings.local.json", "Claude Code local settings written by cce init"),
+    # `.mcp.json` carries an absolute path to the `cce` binary (different
+    # on each contributor's machine) and a project_dir argument that's
+    # also absolute. Committing it would force every contributor to
+    # share one path layout, which never holds. `cce init` regenerates
+    # it on each machine, so gitignoring it is the correct default.
+    (".mcp.json", ".mcp.json contains absolute paths regenerated by `cce init`"),
 ]
 
 
diff --git a/tests/test_project_commands.py b/tests/test_project_commands.py
index 55f958f..5752697 100644
--- a/tests/test_project_commands.py
+++ b/tests/test_project_commands.py
@@ -387,6 +387,21 @@ def test_doesnt_duplicate_if_present(self, tmp_path):
         content = (tmp_path / ".gitignore").read_text()
         assert content.count(".cce/") == 1
 
+    def test_ignores_mcp_json(self, tmp_path):
+        """`.mcp.json` contains absolute paths and is regenerated by
+        `cce init` on each machine — must be in the managed
+        gitignore block so contributors don't accidentally commit
+        each other's path layouts."""
+        ensure_gitignore(str(tmp_path))
+        content = (tmp_path / ".gitignore").read_text()
+        assert ".mcp.json" in content
+
+    def test_mcp_json_not_duplicated_if_user_already_ignored(self, tmp_path):
+        (tmp_path / ".gitignore").write_text(".mcp.json\nnode_modules/\n")
+        ensure_gitignore(str(tmp_path))
+        content = (tmp_path / ".gitignore").read_text()
+        assert content.count(".mcp.json") == 1
+
 
 # ── Edge cases ─────────────────────────────────────────────────────────