Add GHA workflow to diff slides with batch script

Author: joshuacwnewton

.github/workflows/compare_script_to_course.yml

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+name: Compare SCT Commands
+
+on:
+  pull_request:
+  workflow_dispatch:
+    inputs:
+      text_url:
+        description: "URL to text file (e.g. GitHub raw gist link)"
+        required: true
+        type: string
+
+jobs:
+  compare:
+    runs-on: macos-latest
+    env:
+      YDIFF_OPTIONS: "--unified --pager=cat --color=always --width=120 --nowrap"
+
+    steps:
+      - name: Check out repo
+        uses: actions/checkout@v4
+
+      - name: Install Python (for parsing script)
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.11"
+
+      - name: Install `ydiff`  # https://github.com/ymattw/ydiff
+        run: brew install ydiff
+
+      - name: Download remote text file
+        run: |
+          curl -L https://gist.githubusercontent.com/joshuacwnewton/3c554bf27111cf0020e5c124b66448c4/raw/ff08cbcf7738941008eca0fa54e024d98eea24e8/gistfile1.txt -o remote.txt
+          echo "✅ Downloaded remote file:"
+          wc -l remote.txt
+
+      - name: Extract commands from remote file
+        run: |
+          python3 .github/workflows/scripts/extract_sct.py remote.txt -o remote_cmds.txt
+          sort -u remote_cmds.txt > remote_cmds_sorted.txt
+          echo "✅ Extracted $(wc -l < remote_cmds_sorted.txt) commands from remote file"
+
+      - name: Extract commands from local batch script
+        run: |
+          python3 .github/workflows/scripts/extract_sct.py single_subject/batch_single_subject.sh -o local_cmds.txt
+          sort -u local_cmds.txt > local_cmds_sorted.txt
+          echo "✅ Extracted $(wc -l < local_cmds_sorted.txt) commands from local script"
+
+      - name: Diff commands
+        run: |
+          echo "🔍 Diffing remote vs local..."
+          diff -u local_cmds_sorted.txt remote_cmds_sorted.txt > diff.txt || true
+          ydiff < diff.txt
+
+      - name: Upload results as artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: command-diff-output
+          path: |
+            remote_cmds_sorted.txt
+            local_cmds_sorted.txt

.github/workflows/scripts/extract_sct.py

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+import argparse
+from pathlib import Path
+
+
+def extract_sct_commands(paths, output=None):
+    results = []
+
+    for path in paths:
+        with open(path, "r", encoding="utf-8") as f:
+            for line in f:
+                stripped = line.lstrip()
+                if stripped.startswith("# sct_"):
+                    stripped = stripped[2:]
+                # Find relavent SCT commands to compare
+                if (stripped.startswith("sct_")
+                        # sct commands must have command + arg + value (3)
+                        # this excludes slide subtitles like "sct_slide ..."
+                        and len(stripped.split(" ")) >= 3
+                        # exclude lines with <> which are likely placeholders
+                        and not ("<" in stripped and ">" in stripped)
+                        # exclude sct_download_data (data already present)
+                        and not stripped.startswith("sct_download_data")
+                        # exclude sct_run_batch (handled in .yml workflow)
+                        and not stripped.startswith("sct_run_batch")):
+                    results.append(stripped.rstrip())
+
+    if output:
+        Path(output).write_text("\n".join(results), encoding="utf-8")
+    else:
+        print("\n".join(results))
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="Extract SCT commands "
+                                                 "from TXT files.")
+    parser.add_argument("files", nargs="+", help="Input text files")
+    parser.add_argument("-o", "--output", help="Optional output file")
+    args = parser.parse_args()
+
+    extract_sct_commands(args.files, args.output)