diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 22a9b1a..11d91ec 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -14,10 +14,10 @@ jobs:
   test:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
         with:
           persist-credentials: false
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
         with:
           python-version: "3.12"
           cache: pip
@@ -33,10 +33,10 @@ jobs:
         os: [macos-14, windows-latest]
     runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
         with:
           persist-credentials: false
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
         with:
           python-version: "3.12"
           cache: pip
@@ -62,10 +62,10 @@ jobs:
             arch: apple-silicon
     runs-on: ${{ matrix.runner }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
         with:
           persist-credentials: false
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
         with:
           python-version: "3.12"
           cache: pip
@@ -84,7 +84,7 @@ jobs:
           # tested here — confirm the embedded interpreter starts and imports.
           "$APP/Contents/MacOS/WebP Studio" --check
       - run: ditto -c -k --keepParent "dist/WebP Studio.app" "WebP-Studio-macOS-${{ matrix.arch }}.zip"
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
         with:
           name: WebP-Studio-macOS-${{ matrix.arch }}
           path: WebP-Studio-macOS-${{ matrix.arch }}.zip
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
new file mode 100644
index 0000000..545b0f5
--- /dev/null
+++ b/.github/workflows/release.yml
@@ -0,0 +1,73 @@
+name: Release
+
+on:
+  push:
+    tags: ["v*.*.*"]
+
+# Only the publish job needs to write, to create the release and attach assets.
+permissions:
+  contents: read
+
+jobs:
+  macos-app:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          # py2app bundles the running interpreter, so a single runner produces
+          # a single-arch app that will not launch on the other kind of Mac.
+          - runner: macos-15-intel
+            arch: intel
+          - runner: macos-14
+            arch: apple-silicon
+    runs-on: ${{ matrix.runner }}
+    steps:
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
+        with:
+          persist-credentials: false
+      - uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
+        with:
+          python-version: "3.12"
+          cache: pip
+      - run: |
+          pip install -r requirements.txt
+          pip install py2app
+      - run: python setup.py py2app
+      - name: Verify the bundle launches
+        run: |
+          APP="dist/WebP Studio.app"
+          test -d "$APP" || { echo "no bundle produced"; exit 1; }
+          "$APP/Contents/MacOS/WebP Studio" --check
+      - run: ditto -c -k --keepParent "dist/WebP Studio.app" "WebP-Studio-macOS-${{ matrix.arch }}.zip"
+      - uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
+        with:
+          name: WebP-Studio-macOS-${{ matrix.arch }}
+          path: WebP-Studio-macOS-${{ matrix.arch }}.zip
+          retention-days: 5
+
+  publish:
+    needs: macos-app
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+    steps:
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
+        with:
+          persist-credentials: false
+      - uses: actions/download-artifact@634f93cb2916e3fdff6788551b99b062d0335ce0 # v5
+        with:
+          pattern: WebP-Studio-macOS-*
+          path: dist
+          merge-multiple: true
+      - name: Create GitHub Release
+        env:
+          GH_TOKEN: ${{ github.token }}
+          # Templated into the run script as literal text, so a tag crafted
+          # with shell metacharacters would be interpreted by bash. Passing
+          # it through env and referencing $TAG_NAME instead means the shell
+          # only ever sees it as a variable's value, never as script text.
+          TAG_NAME: ${{ github.ref_name }}
+        run: |
+          gh release create "$TAG_NAME" dist/*.zip \
+            --title "$TAG_NAME" \
+            --generate-notes
diff --git a/README.md b/README.md
index 2d34cec..855d8d8 100644
--- a/README.md
+++ b/README.md
@@ -63,12 +63,15 @@ python main.py --check
 
 ### Prebuilt macOS app
 
-No signed releases yet — grab a build straight from CI instead:
-[**Actions → Build → latest run**](https://github.com/DhakadG/ConvertImagesToWebP-MacApp/actions/workflows/build.yml)
-→ pick `WebP-Studio-macOS-apple-silicon` or `WebP-Studio-macOS-intel` under
-Artifacts. Unzip, then see [Gatekeeper](#the-app-is-damaged-and-cant-be-opened)
-below before opening it. Artifacts expire after 14 days, so if the run has
-aged out, use `workflow_dispatch` to trigger a fresh one from the Actions tab.
+Grab the latest build from [**Releases**](https://github.com/DhakadG/ConvertImagesToWebP-MacApp/releases) —
+pick `WebP-Studio-macOS-apple-silicon.zip` or `WebP-Studio-macOS-intel.zip`.
+Unzip, then see [Gatekeeper](#the-app-is-damaged-and-cant-be-opened) below
+before opening it. These are unsigned dev builds cut from tags, not
+App Store releases.
+
+No tagged release yet, or want the very latest commit instead? Grab a build
+straight from CI: [**Actions → Build → latest run**](https://github.com/DhakadG/ConvertImagesToWebP-MacApp/actions/workflows/build.yml)
+→ Artifacts. Those expire after 14 days; run `workflow_dispatch` for a fresh one.
 
 ## macOS
 
@@ -180,6 +183,18 @@ no window server, so that last step is yours.
 Issues and PRs welcome. `python tests/test_engine.py` should stay green with
 no display, and CI runs it plus the GUI boot suite on every PR.
 
+### Cutting a release
+
+Push a tag matching `v*.*.*`:
+
+```bash
+git tag v2.0.0
+git push origin v2.0.0
+```
+
+`.github/workflows/release.yml` builds both macOS bundles and publishes them
+to a new GitHub Release, titled after the tag with auto-generated notes.
+
 ## License
 
 [MIT](LICENSE).
diff --git a/core/imaging.py b/core/imaging.py
index 45cefff..5892bd8 100644
--- a/core/imaging.py
+++ b/core/imaging.py
@@ -14,9 +14,13 @@
 
 from core.config import Settings
 
-# We routinely handle 100 MP camera scans; the decompression-bomb guard is for
-# untrusted input, and these files come from the user's own disk.
-Image.MAX_IMAGE_PIXELS = None
+# Raised, not disabled: legitimate scans and panoramas run well past Pillow's
+# ~89 MP default, but a folder can still contain a downloaded or crafted file
+# with an absurd declared size. Pillow itself only *warns* (doesn't raise)
+# between 1x and 2x this value, so the real gate is the explicit check in
+# convert_file below; this just keeps Pillow's own internal calls bounded too.
+MAX_PIXELS = 300_000_000
+Image.MAX_IMAGE_PIXELS = MAX_PIXELS
 
 # Optional decoders. Both are pure-import side effects, so probe once at module
 # load rather than per-file.
@@ -224,11 +228,25 @@ def _check_dimensions(width: int, height: int, output_format: str) -> None:
             f"{limit}px — set a downscale limit, or choose PNG/AVIF")
 
 
+def _check_pixel_count(width: int, height: int) -> None:
+    """Pillow only warns, and still decodes, between 1x and 2x MAX_PIXELS —
+    this is the actual gate. Called right after Image.open(), before any
+    pixel data is touched, so an oversized file costs a header read, not a
+    full decode."""
+    pixels = width * height
+    if pixels > MAX_PIXELS:
+        raise ValueError(
+            f"{width}x{height} ({pixels:,} px) exceeds the {MAX_PIXELS:,} px "
+            f"safety limit — skipped before decoding")
+
+
 def convert_file(source: Path, destination: Path, settings: Settings) -> Encoded:
     """Convert one image. Raises on failure — the runner turns that into a
     per-file error row so one bad file can't abort the batch."""
     note = ""
     with Image.open(source) as opened:
+        _check_pixel_count(*opened.size)
+
         if getattr(opened, "n_frames", 1) > 1:
             note = "animated source, first frame only"
 
diff --git a/tests/test_engine.py b/tests/test_engine.py
index 0705732..998d47a 100644
--- a/tests/test_engine.py
+++ b/tests/test_engine.py
@@ -15,8 +15,8 @@
 from PIL import Image
 
 from core.config import Settings
-from core.imaging import (_check_dimensions, _target_size, available_output_formats,
-                          convert_file)
+from core.imaging import (MAX_PIXELS, _check_dimensions, _check_pixel_count,
+                          _target_size, available_output_formats, convert_file)
 from core.runner import CONVERTED, FAILED, SKIPPED, Runner, scan_sources, common_root
 
 
@@ -242,6 +242,21 @@ def test_webp_dimension_limit(tmp: Path):
     print("  webp dimension limit ok")
 
 
+def test_pixel_count_limit():
+    """Pillow only warns (still decodes) between 1x and 2x MAX_IMAGE_PIXELS —
+    this must reject anything over the limit itself, not Pillow's fuzzed one."""
+    side = int(MAX_PIXELS ** 0.5)
+    _check_pixel_count(side, side)  # just under the limit: fine
+
+    try:
+        _check_pixel_count(side + 1, side + 1)  # inside Pillow's warn-only zone
+    except ValueError as exc:
+        assert str(MAX_PIXELS) in str(exc).replace(",", ""), exc
+    else:
+        raise AssertionError("image over MAX_PIXELS was not rejected")
+    print("  pixel count limit ok")
+
+
 def test_format_falls_back_to_a_writable_one(tmp: Path):
     """A preset must not select a format this Pillow build cannot encode."""
     settings = Settings.from_dict({"output_format": "avif"})
@@ -272,6 +287,7 @@ def main() -> int:
         test_overwrite_keeps_good_output_when_encode_fails(tmp / "t11")
         test_webp_dimension_limit(tmp / "t12")
         test_format_falls_back_to_a_writable_one(tmp / "t13")
+        test_pixel_count_limit()
     print("\nall engine checks passed")
     return 0