diff --git a/prompts/EXISTING_REPO_CHECKLIST.md b/prompts/EXISTING_REPO_CHECKLIST.md
index 92d68e1..f62e99a 100644
--- a/prompts/EXISTING_REPO_CHECKLIST.md
+++ b/prompts/EXISTING_REPO_CHECKLIST.md
@@ -205,14 +205,14 @@ with your task.
 - [ ] `Makefile` exists in root — reference
       `https://git.eeqj.de/sneak/prompts/raw/branch/main/Makefile`
 - [ ] Has targets: `test`, `lint`, `fmt`, `fmt-check`, `check`, `docker`,
-      `hooks`, `install`, `update-policy`
+      `hooks`, `update-policy`
 - [ ] Target implementations live in `script/` (scripts-to-rule-them-all);
       Makefile targets are thin shims calling them — model scripts at
       `https://git.eeqj.de/sneak/prompts/raw/branch/main/script/<name>`
 - [ ] `script/precommit` exists and the pre-commit hook (installed by
       `script/install-precommit`, shimmed by `make hooks`) runs it
 - [ ] `script/install` and `script/update-policy` exist, identical to the model
-      scripts, and `make install` and `make update-policy` shim to them.
+      scripts, and `make update-policy` shims to `script/update-policy`.
       `make update-policy` commits without pushing, so a person reviews and
       pushes the commit. Before its first use, the repo's own entries in
       `.gitignore`, `.editorconfig` and `.dockerignore` go below the comment
diff --git a/prompts/NEW_REPO_CHECKLIST.md b/prompts/NEW_REPO_CHECKLIST.md
index cc00df2..c5cd5a3 100644
--- a/prompts/NEW_REPO_CHECKLIST.md
+++ b/prompts/NEW_REPO_CHECKLIST.md
@@ -266,9 +266,8 @@ are thin shims calling them. Model scripts:
 - [ ] `script/install-precommit` — installs the pre-commit hook that runs
       `script/precommit`
 - [ ] `make hooks` — shims to `script/install-precommit`
-- [ ] `script/install` / `make install` — fetches the vendored policy files from
-      the `prompts` repo over HTTP and writes them into the repo; identical
-      across repos
+- [ ] `script/install` — fetches the vendored policy files from the `prompts`
+      repo over HTTP and writes them into the repo; identical across repos
 - [ ] `script/update-policy` / `make update-policy` — fetches the current
       `script/install`, runs it on the repo and commits the result without
       pushing; identical across repos
diff --git a/prompts/REPO_POLICIES.md b/prompts/REPO_POLICIES.md
index 8bdaeb3..ae433e1 100644
--- a/prompts/REPO_POLICIES.md
+++ b/prompts/REPO_POLICIES.md
@@ -93,7 +93,6 @@ style conventions are in separate documents:
     - `make check` (runs `test`, `lint`, `fmt-check`)
     - `make docker`
     - `make hooks` (installs pre-commit hook)
-    - `make install` (writes the current policy files into the repo)
     - `make update-policy` (brings the repo up to standards and commits)
 
     A model Makefile is at
@@ -194,7 +193,7 @@ style conventions are in separate documents:
       `make hooks` target shims to it.
     - `script/install` fetches the vendored policy files from the `prompts` repo
       over HTTP and writes them into the repo it is given, or its own repo with
-      no argument. The `make install` target shims to it.
+      no argument.
     - `script/update-policy` fetches the current `script/install` from the
       `prompts` repo, runs it on its own repo and commits the result. It does
       not push. The `make update-policy` target shims to it.
diff --git a/test/update-policy.sh b/test/update-policy.sh
index 9d0451f..8a1ac08 100755
--- a/test/update-policy.sh
+++ b/test/update-policy.sh
@@ -453,6 +453,21 @@ test_language_files_need_a_source_file() {
     expect_new_commit_not_pushed
 }
 
+test_javascript_source_brings_its_styleguide() {
+    for extension in js mjs; do
+        start_scenario "a repo whose only JavaScript source is a .$extension file gets the JavaScript style guide"
+        echo "export {}" > "$dir/repo/web.$extension"
+        commit_and_push_fixture "web.$extension"
+        remove_from_fixture docs/CODE_STYLEGUIDE_JS.md
+        run_update_policy
+        expect_success
+        expect_file docs/CODE_STYLEGUIDE_JS.md << 'EOF'
+new CODE_STYLEGUIDE_JS
+EOF
+        expect_new_commit_not_pushed
+    done
+}
+
 test_nothing_changed() {
     start_scenario "nothing changed"
     cp "$dir/canonical/.prettierrc" "$dir/repo/.prettierrc"
@@ -675,14 +690,16 @@ EOF
 }
 
 test_own_script_stops() {
-    start_scenario "a tracked script/install with a line the canonical file has never held stops"
-    echo "echo our own installer" >> "$dir/repo/script/install"
-    commit_and_push_fixture .prettierrc
-    run_update_policy
-    expect_failure
-    expect_output "script/install has lines"
-    expect_output "echo our own installer"
-    expect_nothing_written
+    for script in script/install script/update-policy; do
+        start_scenario "a tracked $script with a line the canonical file has never held stops"
+        echo "echo our own script" >> "$dir/repo/$script"
+        commit_and_push_fixture .prettierrc
+        run_update_policy
+        expect_failure
+        expect_output "$script has lines"
+        expect_output "echo our own script"
+        expect_nothing_written
+    done
 }
 
 test_gitignore_lacks_canonical_last_line() {
@@ -827,6 +844,7 @@ main() {
     test_own_entries_kept
     test_files_the_repo_lacks_are_written_whole
     test_language_files_need_a_source_file
+    test_javascript_source_brings_its_styleguide
     test_nothing_changed
     test_target_lacking_install_gets_both_scripts
     test_update_policy_replaces_itself