diff --git a/.worktreeignore b/.worktreeignore
deleted file mode 100644
index e39ef00ff..000000000
--- a/.worktreeignore
+++ /dev/null
@@ -1,20 +0,0 @@
-# .worktreeignore
-#
-# Paths that are git-ignored (see .gitignore) but are expensive to regenerate
-# and worth carrying into / sharing across a fresh worktree, so a new worktree
-# is usable immediately instead of after a full rebuild.
-
-# Python virtual environment (expensive `uv sync`)
-.venv
-
-# Build / packaging artifacts
-dist
-build
-
-# Built documentation (expensive Sphinx build)
-documentation/build
-
-# Tool caches that speed up repeated runs
-.mypy_cache
-.pytest_cache
-.coverage
diff --git a/.worktreeinclude b/.worktreeinclude
new file mode 100644
index 000000000..963c851d4
--- /dev/null
+++ b/.worktreeinclude
@@ -0,0 +1,23 @@
+# .worktreeinclude
+#
+# Paths that are git-ignored (see .gitignore) but are expensive to regenerate
+# and worth copying into a fresh worktree, so a new worktree is usable
+# immediately instead of after a full rebuild.
+#
+# Keep this list small: every entry is copied file-by-file into each worktree.
+# Anything large, cheap to regenerate, or holding absolute paths belongs in
+# .gitignore only:
+#   .venv               run `uv sync` in the new worktree instead; a copy is
+#                       ~560 MB / 18k files and its interpreter symlinks point
+#                       back at the source checkout.
+#   .mypy_cache         ~210 MB, and mypy rebuilds it on first run.
+#   documentation/build ~150 MB of Sphinx HTML; rebuild with
+#                       `documentation/make.py` on the rare occasion it is needed.
+
+# Build / packaging artifacts
+dist
+build
+
+# Tool caches that speed up repeated runs
+.pytest_cache
+.coverage