CI: extract changeset guard logic into scripts/changeset-guard.sh (#1244)

The changeset guard added in #1205 kept its bash inline in the workflow's
run: block. Extract it into scripts/changeset-guard.sh (invoked via
run: ./scripts/changeset-guard.sh) so the logic can be linted, tested, and
run locally instead of living inside YAML.

Author: talagluck

.github/workflows/changeset-guard.yaml

@@ -16,49 +16,4 @@ jobs:
             - name: Require a @gitbook/cli changeset when @gitbook/api is bumped
               env:
                   BASE_SHA: ${{ github.event.pull_request.base.sha }}
-              run: |
-                  set -euo pipefail
-
-                  api_re="^['\"]?@gitbook/api['\"]?[[:space:]]*:"
-                  cli_re="^['\"]?@gitbook/cli['\"]?[[:space:]]*:"
-
-                  # Changeset files introduced by THIS PR (added or modified), excluding the README.
-                  pr_changesets=$(git diff --name-only --diff-filter=AM "$BASE_SHA...HEAD" -- '.changeset/*.md' \
-                      | grep -vi '/README\.md$' || true)
-
-                  if [ -z "$pr_changesets" ]; then
-                      echo "No changeset changes in this PR — nothing to check."
-                      exit 0
-                  fi
-
-                  # Does this PR introduce a @gitbook/api bump?
-                  api_bumped=false
-                  while IFS= read -r f; do
-                      [ -n "$f" ] && [ -f "$f" ] || continue
-                      if grep -Eq "$api_re" "$f"; then api_bumped=true; fi
-                  done <<< "$pr_changesets"
-
-                  if [ "$api_bumped" = false ]; then
-                      echo "This PR does not bump @gitbook/api — nothing to enforce."
-                      exit 0
-                  fi
-
-                  # Is there ANY pending @gitbook/cli changeset (from this PR or already on the branch)?
-                  # The release batches all pending changesets, so a @gitbook/cli bump anywhere counts.
-                  cli_bumped=false
-                  for f in .changeset/*.md; do
-                      [ -f "$f" ] || continue
-                      case "$f" in */README.md) continue ;; esac
-                      if grep -Eq "$cli_re" "$f"; then cli_bumped=true; fi
-                  done
-
-                  if [ "$cli_bumped" = false ]; then
-                      echo "::error::This PR bumps @gitbook/api but no pending changeset bumps @gitbook/cli."
-                      echo "The gitbook CLI generates its commands from the API's OpenAPI spec, so an"
-                      echo "@gitbook/api bump should normally also republish the CLI. Add"
-                      echo "\"'@gitbook/cli': patch\" to your changeset (or add a second .changeset/*.md)"
-                      echo "so the CLI is regenerated and released with the new spec."
-                      exit 1
-                  fi
-
-                  echo "Changeset guard passed (a @gitbook/cli changeset is present)."
+              run: ./scripts/changeset-guard.sh

scripts/changeset-guard.sh

@@ -0,0 +1,55 @@
+#!/bin/bash
+
+# Require a @gitbook/cli changeset when @gitbook/api is bumped.
+#
+# The gitbook CLI generates its commands from the API's OpenAPI spec, so an
+# @gitbook/api bump should normally also republish the CLI. This guard fails the
+# PR if it bumps @gitbook/api without any pending @gitbook/cli changeset.
+#
+# Expects BASE_SHA in the environment (the PR base commit to diff against).
+
+set -euo pipefail
+
+api_re="^['\"]?@gitbook/api['\"]?[[:space:]]*:"
+cli_re="^['\"]?@gitbook/cli['\"]?[[:space:]]*:"
+
+# Changeset files introduced by THIS PR (added or modified), excluding the README.
+pr_changesets=$(git diff --name-only --diff-filter=AM "$BASE_SHA...HEAD" -- '.changeset/*.md' \
+    | grep -vi '/README\.md$' || true)
+
+if [ -z "$pr_changesets" ]; then
+    echo "No changeset changes in this PR — nothing to check."
+    exit 0
+fi
+
+# Does this PR introduce a @gitbook/api bump?
+api_bumped=false
+while IFS= read -r f; do
+    [ -n "$f" ] && [ -f "$f" ] || continue
+    if grep -Eq "$api_re" "$f"; then api_bumped=true; fi
+done <<< "$pr_changesets"
+
+if [ "$api_bumped" = false ]; then
+    echo "This PR does not bump @gitbook/api — nothing to enforce."
+    exit 0
+fi
+
+# Is there ANY pending @gitbook/cli changeset (from this PR or already on the branch)?
+# The release batches all pending changesets, so a @gitbook/cli bump anywhere counts.
+cli_bumped=false
+for f in .changeset/*.md; do
+    [ -f "$f" ] || continue
+    case "$f" in */README.md) continue ;; esac
+    if grep -Eq "$cli_re" "$f"; then cli_bumped=true; fi
+done
+
+if [ "$cli_bumped" = false ]; then
+    echo "::error::This PR bumps @gitbook/api but no pending changeset bumps @gitbook/cli."
+    echo "The gitbook CLI generates its commands from the API's OpenAPI spec, so an"
+    echo "@gitbook/api bump should normally also republish the CLI. Add"
+    echo "\"'@gitbook/cli': patch\" to your changeset (or add a second .changeset/*.md)"
+    echo "so the CLI is regenerated and released with the new spec."
+    exit 1
+fi
+
+echo "Changeset guard passed (a @gitbook/cli changeset is present)."