migrate.sh: auto-clone + inline gather/extract bash in publish.yml

docs/how-to/migrate-from-gh-pages.md

@@ -58,8 +58,7 @@ migration has the same inputs — and it deploys to *your* `github.io`, never up
 1. **Fork the repo and enable Actions on the fork** (the **Actions** tab → enable
    workflows; forks start with Actions disabled). You have admin on your own fork,
    which is what the Pages-source flip in step 2 needs.
-2. **Run `migrate.sh` against the fork**, from a clone of it — dry-run first, then for
-   real:
+2. **Run `migrate.sh` against the fork** — dry-run first, then for real:
 
    ```bash
    scripts/migrate.sh FORKORG/REPO --dry-run
@@ -88,12 +87,13 @@ tag to the fork if you also want to rehearse the tag re-dispatch.
 
 ## Before you start
 
-- `gh` authenticated with **repo-admin** on the target repo (flipping the Pages source
-  and setting the environment policy need admin; a CI token can't — which is why this is
-  a local script).
-- Run the script from **inside a clone of the target repo**: it reads the repo's tags
-  and `gh-pages` tree from the working directory (it fetches `origin/gh-pages` for you).
-  Running it from anywhere else will find no tags/branches.
+- Run the script from the **myst-version-switcher-plugin devcontainer** (it needs `gh`,
+  `zip`, and `node`, which the devcontainer provides).
+- Authenticate `gh` with **repo-admin** on the target repo — run `gh auth login` if
+  needed (flipping the Pages source and setting the environment policy need admin; a CI
+  token can't — which is why this is a local script).
+- If the script detects it is running in a clone of the target repo it will use that,
+  otherwise it will clone the repo itself.
 
 ## Step 1 — dry-run (recommended)
 

scripts/migrate.sh

@@ -1,8 +1,9 @@
 #!/usr/bin/env bash
 #
 # One-time gh-pages → durable-source migration, run LOCALLY by an operator from
-# inside a clone of the TARGET repo (it reads that repo's tags and gh-pages tree
-# from the working directory; it fetches origin/gh-pages itself).
+# the myst-version-switcher-plugin devcontainer. If the script detects it is
+# already running inside a clone of the target repo it will use that; otherwise
+# it clones the repo itself into a temporary directory.
 #
 # Why local, not CI (see docs/how-to/migrate-from-gh-pages.md):
 #   - flipping the Pages source needs repo-admin, which a CI GITHUB_TOKEN lacks;
@@ -76,6 +77,18 @@ OWNER="${REPO%%/*}"
 NAME="${REPO##*/}"
 BASE="https://$(echo "$OWNER" | tr '[:upper:]' '[:lower:]').github.io/$NAME"
 
+# Clone the target repo if not already running inside it.
+_tmp_clone=""
+trap '[ -n "$_tmp_clone" ] && rm -rf "$_tmp_clone"' EXIT
+_current_origin=$(git remote get-url origin 2>/dev/null || echo "")
+_normalized=$(printf '%s' "$_current_origin" | sed 's|.*github\.com[:/]||; s|\.git$||')
+if [ "$_normalized" != "$REPO" ]; then
+  _tmp_clone=$(mktemp -d)
+  git clone "https://github.com/$REPO.git" "$_tmp_clone"
+  cd "$_tmp_clone"
+fi
+unset _current_origin _normalized
+
 # Fetch the gh-pages ref into its remote-tracking ref (a bare `git fetch origin
 # gh-pages` only guarantees FETCH_HEAD; we read `$PAGES_REF` by name).
 fetch_pages_ref() {