fix: apply medium/high severity code review findings

- Re-raise worker futures in as_completed to surface thread exceptions
- Replace hardcoded extension set with ALLOWED_EXT constant in compress_with_caesium
- Initialise work_dir/scratch_dir to None before try block to prevent NameError in finally
- Remove unused dead function get_slide_numbers_for_image
- Simplify redundant caesium_threads guard (threads and threads > 1 -> threads > 1)
- Write [Content_Types].xml first in ZIP to satisfy OOXML spec

Co-Authored-By: Abacus.AI CLI <agent@abacus.ai>

README.md

@@ -1,6 +1,6 @@
 
 # PPTX Image Compressor (CaesiumCLT only)
-**Version 1.1.4**
+**Version 1.1.6**
 
 Dieses Paket enthält:
 
@@ -11,8 +11,6 @@ PPTX-Image-Compressor/
 ├─ pptx_image_compress.py
 ├─ bin/
 │  └─ caesiumclt.exe
-└─ samples/
-   └─ README.txt
 ```
 
 ## Schnellstart (ohne Admin-Rechte)
@@ -34,6 +32,7 @@ Die Batch lädt bei Bedarf automatisch das **Windows Embeddable Python Package**
 - Entpackt die PPTX in einen Temp‑Ordner
 - Komprimiert **JPG/JPEG, PNG, WebP, GIF** mit **CaesiumCLT** (Default `-q 90`, `-O bigger`)
 - Ersetzt Bilder nur, wenn die komprimierte Datei kleiner ist
+- Ersetzt Bilder nur, wenn sei mindestens 2% kleiner sind (verhindert *doppelte Komprimierung*)
 - Schreibt ein CSV‑Log (`.log` neben der Output‑PPTX)
 - Baut eine neue PPTX und zeigt eine Summary (Name, Größe vorher/nachher, Ersparnis %, Zeit)
 - Räumt alle temporären Dateien auf (keine Caesium‑Tempfiles in der finalen PPTX)
@@ -41,6 +40,7 @@ Die Batch lädt bei Bedarf automatisch das **Windows Embeddable Python Package**
 ## Hinweise
 - `-t` steuert die Parallelität der Python‑Threads; intern wird `caesiumclt --threads 1` gesetzt, sobald `-t > 1`, um Oversubscription zu vermeiden. Default ist 16
 -  `-q` steuert das Qualitätslevel; intern wird `caesiumclt -q` mit diesem Wert von `0..100` benutzt, Default ist 90
+-  `--min-savings` steuert das Mindestmass an Komprimierung zur Verhinderung von doppelter Komprimierunt, Default ist 2%
 - Die Batch **verwendet bevorzugt das Embeddable Python** neben der BAT; ansonsten sucht sie echte `python.exe`/`py.exe` im PATH, **ignoriert** aber die Microsoft‑Store‑Alias‑Pfade (`WindowsApps`).
 
 ## Manuelle Nutzung des .py (falls Python vorhanden)

pptx_image_compress.py

@@ -116,10 +116,16 @@ def print_progress(i: int, total: int):
     print(f"\rBilder: |{bar}| {i}/{total} ({pct}%)", end="", flush=True)
 
 def zip_dir_to_pptx(src_dir: Path, out_pptx: Path):
-    with zipfile.ZipFile(out_pptx, "w", compression=zipfile.ZIP_DEFLATED) as z:
+    all_files: list[Path] = []
     for root, _, files in os.walk(src_dir):
         for f in files:
-                full = Path(root) / f
+            all_files.append(Path(root) / f)
+
+    content_types = [f for f in all_files if f.name == "[Content_Types].xml"]
+    rest = [f for f in all_files if f.name != "[Content_Types].xml"]
+
+    with zipfile.ZipFile(out_pptx, "w", compression=zipfile.ZIP_DEFLATED) as z:
+        for full in content_types + rest:
             rel = full.relative_to(src_dir)
             z.write(full, arcname=str(rel))
 
@@ -132,7 +138,7 @@ def compress_with_caesium(original: Path, out_dir: Path, caesium_threads: int |
         raise RuntimeError("[ERROR] 'caesiumclt' wurde nicht gefunden. Bitte CaesiumCLT installieren und in PATH verfügbar machen.")
     out_dir.mkdir(parents=True, exist_ok=True)
     ext = original.suffix.lower()
-    if ext not in {".jpg", ".jpeg", ".png", ".webp", ".gif"}:
+    if ext not in ALLOWED_EXT:
         return None
     cmd = [exe, "-q", str(quality), "-O", "bigger", "--min-savings", min_savings, "-o", str(out_dir)]
     if caesium_threads is not None:
@@ -187,12 +193,6 @@ def build_image_slide_index(rels_dir: Path) -> dict[str, List[int]]:
     return {img: sorted(slides) for img, slides in image_to_slides.items()}
 
 
-def get_slide_numbers_for_image(rels_dir: Path, image_filename: str) -> Optional[List[int]]:
-    image_to_slides = build_image_slide_index(rels_dir)
-    slides = image_to_slides.get(image_filename)
-    return slides if slides else None
-
-
 def process_image_file(
     idx: int,
     img_path: Path,
@@ -243,6 +243,8 @@ def process_single_deck(
         input=str(input_pptx),
         output=str(output_pptx),
     )
+    work_dir: Optional[Path] = None
+    scratch_dir: Optional[Path] = None
 
     try:
         if not input_pptx.exists() or input_pptx.suffix.lower() != ".pptx":
@@ -253,7 +255,6 @@ def process_single_deck(
 
         work_dir = Path(tempfile.mkdtemp(prefix=TEMP_PREFIX + "work_"))
         scratch_dir = Path(tempfile.mkdtemp(prefix=TEMP_PREFIX + "scratch_"))
-
         log_file = output_pptx.with_suffix(".log.csv")
         ensure_clean_file(log_file)
         log_lines = ["image_name;size_before(kb);size_after(kb);saving(kb);saving_percent(%);in_slide_number\n"]
@@ -277,7 +278,7 @@ def process_single_deck(
         if not which("caesiumclt") and compressor is compress_with_caesium:
             raise RuntimeError("'caesiumclt' nicht gefunden. Bitte installieren und in PATH verfügbar machen.")
 
-        caesium_threads = 1 if threads and threads > 1 else None
+        caesium_threads = 1 if threads > 1 else None
         lock = Lock()
         done_count = 0
         image_to_slides = build_image_slide_index(rels_dir)
@@ -303,8 +304,11 @@ def process_single_deck(
         if total > 0:
             with ThreadPoolExecutor(max_workers=max(1, threads)) as ex:
                 futures = [ex.submit(worker, i, p) for i, p in enumerate(images, start=1)]
-                for _ in as_completed(futures):
-                    pass
+                for fut in as_completed(futures):
+                    try:
+                        fut.result()
+                    except Exception as exc:
+                        sys.stderr.write(f"[worker] Unerwarteter Fehler: {exc}\n")
 
         print()  # newline
 
@@ -351,14 +355,10 @@ def process_single_deck(
     except Exception as e:
         result.error = str(e)
     finally:
-        try:
-            shutil.rmtree(work_dir, ignore_errors=True)  # type: ignore[name-defined]
-        except Exception:
-            pass
-        try:
-            shutil.rmtree(scratch_dir, ignore_errors=True)  # type: ignore[name-defined]
-        except Exception:
-            pass
+        if work_dir is not None:
+            shutil.rmtree(work_dir, ignore_errors=True)
+        if scratch_dir is not None:
+            shutil.rmtree(scratch_dir, ignore_errors=True)
         cleanup_old_temps()
 
     return result