fix: check-git-install pins only the layer's commit and builds the playground config

- the lockfile check counts only vue-journal-layer's commit, so the layer's
  own git dependency on vue-seo-layer no longer fails it
- the scratch app takes the playground's nuxt.config.ts and app.vue (the
  search route, one post per category page, the layout trail), which
  testing/expect-acme.txt is written against
- --self-test checks the lockfile reading

scripts/check-git-install.sh

@@ -1,10 +1,12 @@
 #!/usr/bin/env bash
 # Usage: scripts/check-git-install.sh <tag>
+#        scripts/check-git-install.sh --self-test   (the lockfile check only)
 #
 # Proves the layer's distribution end to end: a scratch app installs
 # vue-journal-layer from git+https://git.golem15.com/golem15/vue-journal-layer.git#<tag>
-# anonymously, the lockfile pins the tag's commit, `nuxt build` succeeds, and
-# the built server passes testing/expect-acme.txt against the fixture API.
+# anonymously, the lockfile pins the tag's commit, `nuxt build` of the layer's
+# playground config succeeds, and the built server passes
+# testing/expect-acme.txt against the fixture API.
 # Nothing outside a temporary directory is touched.
 set -euo pipefail
 
@@ -12,6 +14,35 @@ REPO_URL="https://git.golem15.com/golem15/vue-journal-layer.git"
 
 die() { echo "check-git-install: $*" >&2; exit 1; }
 
+# lock_commits FILE prints the commits FILE pins for vue-journal-layer, one
+# per line: the #<commit> of its git+https entries and the commit of a
+# resolution whose repo is the layer's. Other git dependencies are ignored.
+lock_commits() {
+  {
+    grep -oE 'vue-journal-layer\.git#[0-9a-f]{40}' "$1" | cut -d'#' -f2
+    grep -oE 'commit: [0-9a-f]{40}, repo: [^,}]*/vue-journal-layer\.git' "$1" | grep -oE '[0-9a-f]{40}'
+  } | sort -u
+}
+
+if [[ "${1:-}" == "--self-test" ]]; then
+  lock="$(mktemp)"
+  trap 'rm -f "$lock"' EXIT
+  j=1111111111111111111111111111111111111111
+  s=2222222222222222222222222222222222222222
+  cat >"$lock" <<LOCK
+      vue-journal-layer:
+        specifier: git+https://git.golem15.com/golem15/vue-journal-layer.git#v1.0.0
+        version: git+https://git.golem15.com/golem15/vue-journal-layer.git#$j(abcdef0123456789abcdef0123456789)
+  vue-journal-layer@git+https://git.golem15.com/golem15/vue-journal-layer.git#$j:
+    resolution: {commit: $j, repo: https://git.golem15.com/golem15/vue-journal-layer.git, type: git}
+  vue-seo-layer@git+https://git.golem15.com/golem15/vue-seo-layer.git#$s:
+    resolution: {commit: $s, repo: https://git.golem15.com/golem15/vue-seo-layer.git, type: git}
+LOCK
+  [[ "$(lock_commits "$lock")" == "$j" ]] || die "self-test: lock_commits gave $(lock_commits "$lock" | tr '\n' ' '), want only $j"
+  echo "check-git-install: self-test ok"
+  exit 0
+fi
+
 TAG="${1:-}"
 [[ -n "$TAG" ]] || die "usage: $0 <tag>"
 
@@ -58,30 +89,28 @@ allowBuilds:
   vue-demi: true
 YAML
 
-cat >nuxt.config.ts <<'TS'
-export default defineNuxtConfig({
-  extends: ['vue-journal-layer'],
-  compatibilityDate: '2025-07-15',
-  site: { url: 'https://acme.test', name: 'Acme Blog' },
-  i18n: {
-    strategy: 'prefix_except_default',
-    defaultLocale: 'en',
-    locales: [
-      { code: 'en', language: 'en-US' },
-      { code: 'pl', language: 'pl-PL' },
-    ],
-  },
-})
-TS
-
 GIT_TERMINAL_PROMPT=0 pnpm install || die "pnpm install failed"
 
-# The lockfile must pin the tag's commit, not a branch.
-LOCK_SHA="$(grep -oE "vue-journal-layer[^[:space:]]*[0-9a-f]{40}|commit: [0-9a-f]{40}" pnpm-lock.yaml | grep -oE '[0-9a-f]{40}' | sort -u)"
+# The lockfile must pin the tag's commit, not a branch. Only the
+# vue-journal-layer entries count: the layer's own git dependencies
+# (vue-seo-layer) are pinned in the same file.
+LOCK_SHA="$(lock_commits pnpm-lock.yaml)"
 [[ -n "$LOCK_SHA" ]] || die "pnpm-lock.yaml records no commit for vue-journal-layer"
-[[ "$(wc -l <<<"$LOCK_SHA")" -eq 1 ]] || die "pnpm-lock.yaml records more than one commit: $LOCK_SHA"
+[[ "$(wc -l <<<"$LOCK_SHA")" -eq 1 ]] || die "pnpm-lock.yaml records more than one vue-journal-layer commit: $LOCK_SHA"
 [[ "$LOCK_SHA" == "$TAG_SHA" ]] || die "pnpm-lock.yaml pins $LOCK_SHA, tag $TAG is $TAG_SHA"
 
+# The scratch app is the layer's playground (its journal options, such as
+# the search route and one post per category page, and its app.vue with the
+# search box and the layout trail), which testing/expect-acme.txt is
+# written against, extending the installed layer instead of '..'.
+PLAYGROUND=node_modules/vue-journal-layer/.playground
+[[ -f "$PLAYGROUND/nuxt.config.ts" && -f "$PLAYGROUND/app/app.vue" ]] \
+  || die "the installed layer has no .playground/nuxt.config.ts and .playground/app/app.vue"
+sed "s#extends: \['\.\.'\]#extends: ['vue-journal-layer']#" "$PLAYGROUND/nuxt.config.ts" >nuxt.config.ts
+grep -q "extends: \['vue-journal-layer'\]" nuxt.config.ts || die "the playground's nuxt.config.ts does not extend '..'"
+mkdir -p app
+cp "$PLAYGROUND/app/app.vue" app/app.vue
+
 pnpm exec nuxt build || die "nuxt build failed"
 
 node node_modules/vue-journal-layer/testing/smoke-ssr.mjs \