diff --git a/README.md b/README.md
index 0a5dfe6..3524f82 100644
--- a/README.md
+++ b/README.md
@@ -20,7 +20,6 @@ To make that instance work with the app on your phone, create a tunnel (ngrok, C
 
 These are the next things we want in the app. If you'd like to take one on, read [CONTRIBUTING.md](CONTRIBUTING.md) first.
 
-- A native image viewer, instead of opening images in a browser sheet
 - Styling for livestreams
 - Search
 - A notifications centre that matches the web
diff --git a/app/Devnull/Data/CommitImage.php b/app/Devnull/Data/CommitImage.php
index 70635f3..c758f78 100644
--- a/app/Devnull/Data/CommitImage.php
+++ b/app/Devnull/Data/CommitImage.php
@@ -61,4 +61,17 @@ public function ratio(): float
 
         return round(max(self::TallestRatio, $this->width / $this->height), 4);
     }
+
+    /**
+     * Width over height as the image really is, uncapped, for drawing it whole;
+     * null when devnull didn't send its size.
+     */
+    public function naturalRatio(): ?float
+    {
+        if ($this->width === 0 || $this->height === 0) {
+            return null;
+        }
+
+        return round($this->width / $this->height, 4);
+    }
 }
diff --git a/app/Icons/Lucide.php b/app/Icons/Lucide.php
index e209092..2a123ea 100644
--- a/app/Icons/Lucide.php
+++ b/app/Icons/Lucide.php
@@ -32,6 +32,7 @@ enum Lucide
     case Trash2;
     case CornerDownRight;
     case ChevronRight;
+    case ChevronLeft;
     case ChevronDown;
     case ArrowUpRight;
     case ArrowUp;
@@ -192,6 +193,7 @@ public function ios(bool $filled = false): Ios|string
         return $this->custom($filled) ?? match ($this) {
             self::CornerDownRight => Ios::ArrowTurnDownRight,
             self::ChevronRight => Ios::ChevronRight,
+            self::ChevronLeft => Ios::ChevronLeft,
             self::ChevronDown => Ios::ChevronDown,
             self::ArrowUpRight => Ios::ArrowUpRight,
             self::Pin => Ios::Pin,
@@ -209,6 +211,7 @@ public function android(bool $filled = false): AndroidSymbol|string
         return $this->custom($filled) ?? match ($this) {
             self::CornerDownRight => AndroidOutlined::SubdirectoryArrowRight,
             self::ChevronRight => AndroidOutlined::ChevronRight,
+            self::ChevronLeft => AndroidOutlined::ChevronLeft,
             self::ChevronDown => AndroidOutlined::ExpandMore,
             self::ArrowUpRight => AndroidOutlined::ArrowOutward,
             self::Pin => AndroidOutlined::PushPin,
diff --git a/app/NativeComponents/Concerns/ShowsCommits.php b/app/NativeComponents/Concerns/ShowsCommits.php
index c13f821..cdf12ab 100644
--- a/app/NativeComponents/Concerns/ShowsCommits.php
+++ b/app/NativeComponents/Concerns/ShowsCommits.php
@@ -5,6 +5,7 @@
 use App\Devnull\Account;
 use App\Devnull\Client;
 use App\Devnull\Data\Commit;
+use App\Devnull\Data\CommitImage;
 use App\Devnull\Data\Pasteis;
 use App\Devnull\Data\User;
 use App\Devnull\ErrorCode;
@@ -12,6 +13,7 @@
 use App\Devnull\ResponseCache;
 use Closure;
 use Native\Mobile\Attributes\On;
+use Native\Mobile\Edge\SharedValue;
 use Native\Mobile\Events\Alert\ButtonPressed;
 use Native\Mobile\Facades\Browser;
 use Native\Mobile\Facades\Dialog;
@@ -21,8 +23,9 @@
  * The actions under a commit: the star, the pastel in pastéis mode, Quote,
  * Reply, and the More menu's Save commit, Share link, Pin to profile, Report
  * commit and Delete commit (Quote and Report open a sheet, see
- * OpensCommitSheet), plus opening its link preview or images in the in-app
- * browser, "Show more" on a long one, and voting on its poll (see
+ * OpensCommitSheet), plus opening its link preview in the in-app browser, its
+ * images full-screen in the app (see partials/image-viewer), "Show more" on a
+ * long one, and voting on its poll (see
  * VotesOnPolls). Taps name the commit rather than a URL, so a URL is never
  * rebuilt from an attribute.
  *
@@ -49,6 +52,37 @@ trait ShowsCommits
      */
     public ?string $deleting = null;
 
+    /**
+     * Whether the image viewer is up, over everything else on the screen,
+     * sheet included.
+     */
+    public bool $viewerOpen = false;
+
+    /**
+     * The images of the commit being viewed, as they were when it opened, so
+     * the viewer keeps what it shows while it slides away even if the commit
+     * leaves the screen.
+     *
+     * @var list<CommitImage>
+     */
+    public array $viewerImages = [];
+
+    /**
+     * Which of the viewer's images is showing.
+     */
+    public int $viewerIndex = 0;
+
+    /**
+     * The zoom and pan of the image being viewed, driven on the phone by the
+     * viewer's gesture area. Fresh ones on every open and every move between
+     * images, so each starts at rest; nulled on close.
+     */
+    public ?SharedValue $viewerZoom = null;
+
+    public ?SharedValue $viewerPanX = null;
+
+    public ?SharedValue $viewerPanY = null;
+
     /**
      * Every commit the screen is showing.
      *
@@ -194,9 +228,62 @@ public function openLinkPreview(string $id): void
         $this->openInBrowser($this->shownCommit($id)?->linkPreview?->url);
     }
 
+    /**
+     * Opens a commit's image full-screen in the app (see partials/image-viewer),
+     * from the one the row tapped: the image whole rather than cropped, pinch
+     * zoom between its whole self and four times, a drag to pan, and the
+     * chevrons under it to move between the commit's other images. An image the
+     * screen isn't showing, or one at no web address, opens nothing, as it did
+     * in the browser.
+     */
     public function openImage(string $id, int $index = 0): void
     {
-        $this->openInBrowser(($this->shownCommit($id)?->images[$index] ?? null)?->url);
+        $images = $this->shownCommit($id)?->images ?? [];
+        $image = $images[$index] ?? null;
+
+        if ($image === null || ! $this->isWebUrl($image->url)) {
+            return;
+        }
+
+        $this->viewerImages = $images;
+        $this->viewerIndex = $index;
+        $this->restViewerImage();
+        $this->viewerOpen = true;
+    }
+
+    /**
+     * The chevron under the viewer: the commit's next image, at rest again. At
+     * the last image there's no chevron to press, and a next at no web address
+     * goes nowhere, as an image at one never opens.
+     */
+    public function viewNextImage(): void
+    {
+        $this->showInViewedImage($this->viewerIndex + 1);
+    }
+
+    /**
+     * The chevron under the viewer: the commit's previous image, at rest
+     * again. At the first image there's no chevron to press, and a previous at
+     * no web address goes nowhere either.
+     */
+    public function viewPreviousImage(): void
+    {
+        $this->showInViewedImage($this->viewerIndex - 1);
+    }
+
+    /**
+     * The viewer's close, back or outside tap, however the phone reports it:
+     * the viewer goes and forgets the image and what its gestures left behind,
+     * so the next one opens as this one did.
+     */
+    public function closeImageViewer(): void
+    {
+        $this->viewerOpen = false;
+        $this->viewerImages = [];
+        $this->viewerIndex = 0;
+        $this->viewerZoom = null;
+        $this->viewerPanX = null;
+        $this->viewerPanY = null;
     }
 
     /**
@@ -452,8 +539,46 @@ private function shownCommit(string $id): ?Commit
 
     private function openInBrowser(?string $url): void
     {
-        if ($url !== null && in_array(parse_url($url, PHP_URL_SCHEME), ['http', 'https'], true)) {
+        if ($this->isWebUrl($url)) {
             Browser::inApp($url);
         }
     }
+
+    /**
+     * Only an http or https address is opened, in the browser or the viewer, so
+     * nothing else a row might carry can take the phone somewhere unexpected.
+     */
+    private function isWebUrl(?string $url): bool
+    {
+        return $url !== null && in_array(parse_url($url, PHP_URL_SCHEME), ['http', 'https'], true);
+    }
+
+    /**
+     * Puts the viewer's image back at rest: fresh shared values, which the
+     * phone seeds at one and none, so what the last image's gestures left
+     * behind can't carry over to it.
+     */
+    private function restViewerImage(): void
+    {
+        $this->viewerZoom = SharedValue::make(1.0);
+        $this->viewerPanX = SharedValue::make();
+        $this->viewerPanY = SharedValue::make();
+    }
+
+    /**
+     * Moves the viewer to one of its commit's images by its place among them,
+     * or nowhere when there's no image there or it's at no web address, so the
+     * viewer never comes to show one the phone shouldn't be asked for.
+     */
+    private function showInViewedImage(int $index): void
+    {
+        $image = $this->viewerImages[$index] ?? null;
+
+        if (! $this->viewerOpen || $image === null || ! $this->isWebUrl($image->url)) {
+            return;
+        }
+
+        $this->viewerIndex = $index;
+        $this->restViewerImage();
+    }
 }
diff --git a/composer.json b/composer.json
index 7ac7e9b..e50cf0f 100644
--- a/composer.json
+++ b/composer.json
@@ -31,12 +31,12 @@
         "laravel/boost": "^2.0",
         "laravel/framework": "^13.0",
         "laravel/tinker": "^3.0",
-        "nativephp/mobile": "dev-main as 4.6.0",
+        "nativephp/mobile": "dev-feat/gesture-area-bounded as 4.6.0",
         "nativephp/mobile-browser": "^1.2",
         "nativephp/mobile-camera": "^1.1",
         "nativephp/mobile-secure-storage": "^1.1",
         "nativephp/mobile-share": "^1.1",
-        "nativephp/mobile-ui": "dev-main as 0.8.0",
+        "nativephp/mobile-ui": "dev-feat/gesture-area-bounded as 0.8.0",
         "s2br/nativephp-mobile-splashscreen": "^1.4"
     },
     "require-dev": {
diff --git a/composer.lock b/composer.lock
index 586e575..b154e11 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "8bcaeeb71989e08fe920116ba3e08bcd",
+    "content-hash": "a5dfa4b4bf563e858153d3744a994e82",
     "packages": [
         {
             "name": "bacon/bacon-qr-code",
@@ -2717,16 +2717,16 @@
         },
         {
             "name": "nativephp/mobile",
-            "version": "dev-main",
+            "version": "dev-feat/gesture-area-bounded",
             "source": {
                 "type": "git",
                 "url": "https://github.com/NativePHP/mobile-air.git",
-                "reference": "2189e72363ea00965c17d35d8b127a2ae77093ad"
+                "reference": "64e04c285d2daa7a0029e849444a74c388b66041"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/NativePHP/mobile-air/zipball/2189e72363ea00965c17d35d8b127a2ae77093ad",
-                "reference": "2189e72363ea00965c17d35d8b127a2ae77093ad",
+                "url": "https://api.github.com/repos/NativePHP/mobile-air/zipball/64e04c285d2daa7a0029e849444a74c388b66041",
+                "reference": "64e04c285d2daa7a0029e849444a74c388b66041",
                 "shasum": ""
             },
             "require": {
@@ -2766,7 +2766,6 @@
             "suggest": {
                 "ext-zip": "Required by native:install to validate and extract the downloaded Android PHP binary archives"
             },
-            "default-branch": true,
             "type": "library",
             "extra": {
                 "laravel": {
@@ -2834,10 +2833,10 @@
                 "nativephp"
             ],
             "support": {
-                "source": "https://github.com/NativePHP/mobile-air/tree/main",
+                "source": "https://github.com/NativePHP/mobile-air/tree/feat/gesture-area-bounded",
                 "issues": "https://github.com/NativePHP/mobile-air/issues"
             },
-            "time": "2026-10-24T01:35:48+00:00"
+            "time": "2026-10-24T02:10:34+00:00"
         },
         {
             "name": "nativephp/mobile-browser",
@@ -3061,16 +3060,16 @@
         },
         {
             "name": "nativephp/mobile-ui",
-            "version": "dev-main",
+            "version": "dev-feat/gesture-area-bounded",
             "source": {
                 "type": "git",
                 "url": "https://github.com/NativePHP/mobile-ui.git",
-                "reference": "0abe5d24dc6c8749ac27a651c66f6b8154459d61"
+                "reference": "d135f295e8d6684868fb9d48f7e7782243520bee"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/NativePHP/mobile-ui/zipball/0abe5d24dc6c8749ac27a651c66f6b8154459d61",
-                "reference": "0abe5d24dc6c8749ac27a651c66f6b8154459d61",
+                "url": "https://api.github.com/repos/NativePHP/mobile-ui/zipball/d135f295e8d6684868fb9d48f7e7782243520bee",
+                "reference": "d135f295e8d6684868fb9d48f7e7782243520bee",
                 "shasum": ""
             },
             "require": {
@@ -3082,7 +3081,6 @@
                 "orchestra/testbench": "^10.0",
                 "pestphp/pest": "^3.0"
             },
-            "default-branch": true,
             "type": "nativephp-plugin",
             "extra": {
                 "laravel": {
@@ -3121,7 +3119,7 @@
             ],
             "description": "Native SwiftUI and Jetpack Composer components for NativePHP",
             "support": {
-                "source": "https://github.com/NativePHP/mobile-ui/tree/main",
+                "source": "https://github.com/NativePHP/mobile-ui/tree/feat/gesture-area-bounded",
                 "issues": "https://github.com/NativePHP/mobile-ui/issues"
             },
             "funding": [
@@ -3130,7 +3128,7 @@
                     "url": "https://nativephp.com/sponsor"
                 }
             ],
-            "time": "2026-10-24T01:25:19+00:00"
+            "time": "2026-10-24T02:05:19+00:00"
         },
         {
             "name": "nesbot/carbon",
@@ -11132,13 +11130,13 @@
     "aliases": [
         {
             "package": "nativephp/mobile",
-            "version": "dev-main",
+            "version": "dev-feat/gesture-area-bounded",
             "alias": "4.6.0",
             "alias_normalized": "4.6.0.0"
         },
         {
             "package": "nativephp/mobile-ui",
-            "version": "dev-main",
+            "version": "dev-feat/gesture-area-bounded",
             "alias": "0.8.0",
             "alias_normalized": "0.8.0.0"
         }
diff --git a/resources/views/native/partials/commit-sheet.blade.php b/resources/views/native/partials/commit-sheet.blade.php
index a9238ed..4d399ee 100644
--- a/resources/views/native/partials/commit-sheet.blade.php
+++ b/resources/views/native/partials/commit-sheet.blade.php
@@ -181,3 +181,5 @@ class="w-full"
         @endif
     @endif
 </native:bottom-sheet>
+
+@include('native.partials.image-viewer')
diff --git a/resources/views/native/partials/image-viewer.blade.php b/resources/views/native/partials/image-viewer.blade.php
new file mode 100644
index 0000000..91ad523
--- /dev/null
+++ b/resources/views/native/partials/image-viewer.blade.php
@@ -0,0 +1,56 @@
+{{--
+    A commit's images full-screen, over everything else on the screen, sheet included (see ShowsCommits): the image
+    the row tapped, whole rather than cropped as it is in the row, on black. A pinch zooms between the image's whole
+    self and four times, around the fingers, and a drag pans it; both run on the phone with no frame trip, so the
+    picture follows a finger. Bounded by the picture's own shape, it can't be lost off screen: zoomed, its edges stop at
+    the screen's, and it stays centred on a side it fits; dragged past that it resists and springs back on release, so
+    at its whole self it always comes back to the middle. The modal's own close, and Android's back, close it.
+
+    Several images in a commit move with the chevrons under the picture, which say their place among them, and each
+    move puts the picture back at rest, as closing and opening another image does. An image still loading, or one that
+    fails, shows whatever its platform's loader shows meanwhile — iOS its spinner, Android nothing — since the image
+    element tells the app nothing about either, there's nothing of the app's to draw here.
+
+    Always in the tree, shown or not, like the sheet, so the phone can animate it away and say when it's gone.
+    Included beside the sheet, so every screen that shows commits has it once.
+--}}
+<native:modal ref="image-viewer" :visible="$viewerOpen" a11y-label="Image viewer" @dismiss="closeImageViewer">
+    @if ($viewerImages !== [])
+        @php($image = $viewerImages[$viewerIndex])
+        <native:column class="w-full h-full bg-black safe-area-bottom">
+            <native:gesture-area ref="viewer-gestures" :pinch="$viewerZoom" pinch-min="1" pinch-max="4" :pan-x="$viewerPanX" :pan-y="$viewerPanY" bounded :content-ratio="$image->naturalRatio()" class="w-full flex-1">
+                <native:column class="w-full h-full items-center justify-center">
+                    <native:image
+                        ref="viewed-image"
+                        :src="\App\Devnull\ImageCache::src($image->url)"
+                        :fit="1"
+                        :scale="$viewerZoom"
+                        :translate-x="$viewerPanX"
+                        :translate-y="$viewerPanY"
+                        class="w-full h-full"
+                        alt="{{ $image->label($viewerIndex, count($viewerImages)) }}"
+                    />
+                </native:column>
+            </native:gesture-area>
+            @if (count($viewerImages) > 1)
+                <native:row ref="viewer-count" class="w-full items-center justify-center gap-8 py-2">
+                    @if ($viewerIndex > 0)
+                        <native:pressable ref="viewed-previous" @press="viewPreviousImage" a11y-label="Previous image">
+                            <native:stack :width="44" :height="44" center class="rounded-full bg-white/20">
+                                <native:icon :ios="\App\Icons\Lucide::ChevronLeft->ios()" :android="\App\Icons\Lucide::ChevronLeft->android()" :size="22" class="text-white" />
+                            </native:stack>
+                        </native:pressable>
+                    @endif
+                    <native:text font="mono" class="text-sm text-white">{{ $viewerIndex + 1 }} of {{ count($viewerImages) }}</native:text>
+                    @if ($viewerIndex < count($viewerImages) - 1)
+                        <native:pressable ref="viewed-next" @press="viewNextImage" a11y-label="Next image">
+                            <native:stack :width="44" :height="44" center class="rounded-full bg-white/20">
+                                <native:icon :ios="\App\Icons\Lucide::ChevronRight->ios()" :android="\App\Icons\Lucide::ChevronRight->android()" :size="22" class="text-white" />
+                            </native:stack>
+                        </native:pressable>
+                    @endif
+                </native:row>
+            @endif
+        </native:column>
+    @endif
+</native:modal>
diff --git a/tests/Feature/Screens/ImageViewerTest.php b/tests/Feature/Screens/ImageViewerTest.php
new file mode 100644
index 0000000..1862e9b
--- /dev/null
+++ b/tests/Feature/Screens/ImageViewerTest.php
@@ -0,0 +1,308 @@
+<?php
+
+use Illuminate\Support\Facades\File;
+use Illuminate\Support\Facades\Http;
+use Native\Mobile\Events\Gallery\MediaSelected;
+use Native\Mobile\Testing\Native;
+use Native\Mobile\Testing\TestableComponent;
+
+beforeEach(function () {
+    config(['devnull.url' => 'http://devnull.test']);
+    signIn();
+});
+
+afterEach(function () {
+    File::deleteDirectory(storage_path('app/draft-images'));
+});
+
+/**
+ * A commit as devnull sends it, with $count images, the first described as the web's alt text.
+ *
+ * @return array<string, mixed>
+ */
+function imagedCommitJson(int $count = 1): array
+{
+    return commitJson(['id' => 'c1', 'images' => array_map(
+        fn (int $index): array => [
+            'id' => 'i'.($index + 1),
+            'url' => 'https://img.test/'.($index + 1),
+            'width' => 10,
+            'height' => 10,
+            'description' => $index === 0 ? 'A cat on a keyboard' : null,
+        ],
+        range(0, $count - 1),
+    )]);
+}
+
+/**
+ * The Following log showing one commit with $count images.
+ */
+function logWithImages(int $count = 1, string $platform = 'ios'): TestableComponent
+{
+    Http::fake(['devnull.test/*' => Http::response(pageJson([imagedCommitJson($count)]))]);
+
+    return Native::visit('/log', platform: $platform);
+}
+
+/**
+ * The images of the imaged commit, for faking another screen that shows it.
+ *
+ * @return list<array<string, mixed>>
+ */
+function imagedCommitImages(): array
+{
+    return imagedCommitJson()['images'];
+}
+
+it('opens a commit\'s image full-screen in the app, not the browser', function (string $platform) {
+    $screen = logWithImages(platform: $platform);
+
+    $screen->tap('image-i1');
+
+    $viewer = nodeByRef($screen, 'image-viewer');
+    $gestures = nodeByRef($screen, 'viewer-gestures');
+    $image = nodeByRef($screen, 'viewed-image');
+    $viewing = $screen->instance();
+
+    expect($viewer['props'])->toMatchArray(['visible' => true, 'a11y_label' => 'Image viewer'])
+        ->and($viewer['props']['on_dismiss'])->not->toBeEmpty()
+        // The image whole, not cropped as it is in the row, read out by the description its author gave it.
+        ->and($image['props'])->toMatchArray(['src' => 'https://img.test/1', 'fit' => 1, 'alt' => 'A cat on a keyboard'])
+        // Pinch bounded one to four, and both pans, settled on the phone against the shared values this open made,
+        // kept on screen by the image's own shape.
+        ->and($gestures['props'])->toMatchArray(['pinch-min' => 1.0, 'pinch-max' => 4.0, 'bounded' => true, 'content-ratio' => 1.0])
+        ->and($gestures['props']['pinch-id'])->toBe($viewing->viewerZoom->id)
+        ->and($gestures['props']['pan-x-id'])->toBe($viewing->viewerPanX->id)
+        ->and($gestures['props']['pan-y-id'])->toBe($viewing->viewerPanY->id)
+        ->and($image['props']['scale_sv'])->toBe((string) $viewing->viewerZoom)
+        ->and($image['props']['translate-x_sv'])->toBe((string) $viewing->viewerPanX)
+        ->and($image['props']['translate-y_sv'])->toBe((string) $viewing->viewerPanY)
+        // One image alone has no chevrons and no place among others.
+        ->and(findNode($screen->tree(), fn (array $node): bool => ($node['ref'] ?? null) === 'viewer-count'))->toBeNull();
+
+    $screen->assertNativeNotCalled('Browser.OpenInApp');
+})->with(['ios', 'android']);
+
+it('keeps an image of no known size on screen by the screen\'s own shape', function () {
+    Http::fake(['devnull.test/*' => Http::response(pageJson([commitJson(['id' => 'c1', 'images' => [
+        ['id' => 'i1', 'url' => 'https://img.test/1'],
+    ]])]))]);
+
+    $screen = Native::visit('/log')->tap('image-i1');
+
+    expect(nodeByRef($screen, 'viewer-gestures')['props'])->toHaveKey('bounded')
+        ->not->toHaveKey('content-ratio');
+});
+
+it('bounds a wide image by its real shape, not the one the feed caps it at', function () {
+    Http::fake(['devnull.test/*' => Http::response(pageJson([commitJson(['id' => 'c1', 'images' => [
+        ['id' => 'i1', 'url' => 'https://img.test/1', 'width' => 300, 'height' => 1200],
+    ]])]))]);
+
+    $screen = Native::visit('/log')->tap('image-i1');
+
+    expect(nodeByRef($screen, 'viewer-gestures')['props']['content-ratio'])->toBe(0.25);
+});
+
+it('starts from the image the row tapped, with the chevrons under it for the commit\'s others', function () {
+    $screen = logWithImages(3)->tap('image-i3');
+
+    expect(nodeByRef($screen, 'viewed-image')['props'])->toMatchArray(['src' => 'https://img.test/3', 'alt' => 'Attached image 3 of 3'])
+        ->and($screen->instance()->viewerIndex)->toBe(2)
+        ->and(shownText($screen))->toContain('3 of 3')
+        // The first image has nothing before it, the last nothing after it, so only the chevron that goes somewhere is drawn.
+        ->and(nodeByRef($screen, 'viewed-previous')['props']['a11y_label'])->toBe('Previous image')
+        ->and(findNode($screen->tree(), fn (array $node): bool => ($node['ref'] ?? null) === 'viewed-next'))->toBeNull();
+
+    $screen->tap('viewed-previous')->tap('viewed-previous');
+
+    expect(nodeByRef($screen, 'viewed-image')['props'])->toMatchArray(['src' => 'https://img.test/1', 'alt' => 'A cat on a keyboard, image 1 of 3'])
+        ->and($screen->instance()->viewerIndex)->toBe(0)
+        ->and(shownText($screen))->toContain('1 of 3')
+        ->and(nodeByRef($screen, 'viewed-next')['props']['a11y_label'])->toBe('Next image')
+        ->and(findNode($screen->tree(), fn (array $node): bool => ($node['ref'] ?? null) === 'viewed-previous'))->toBeNull();
+});
+
+it('moves between the commit\'s images with the chevrons, each image starting at rest', function () {
+    $screen = logWithImages(3)->tap('image-i1');
+
+    $atRest = nodeByRef($screen, 'viewer-gestures')['props'];
+
+    $screen->tap('viewed-next');
+
+    $image = nodeByRef($screen, 'viewed-image');
+    $moved = nodeByRef($screen, 'viewer-gestures')['props'];
+
+    expect($image['props']['src'])->toBe('https://img.test/2')
+        ->and($screen->instance()->viewerIndex)->toBe(1)
+        // Fresh zoom and pans, so what the last image's pinch or drag left behind can't carry over to it.
+        ->and($moved['pinch-id'])->not->toBe($atRest['pinch-id'])
+        ->and($moved['pan-x-id'])->not->toBe($atRest['pan-x-id'])
+        ->and($moved['pan-y-id'])->not->toBe($atRest['pan-y-id'])
+        ->and($image['props']['scale'])->toBe(1.0);
+
+    // Past the last image, the chevron is gone and the call goes nowhere.
+    $screen->tap('viewed-next')->call('viewNextImage');
+
+    expect($screen->instance()->viewerIndex)->toBe(2)
+        ->and(nodeByRef($screen, 'viewed-image')['props']['src'])->toBe('https://img.test/3');
+});
+
+it('opens nothing for an image the screen isn\'t showing, a place with no image, or no web address', function () {
+    Http::fake(['devnull.test/*' => Http::response(pageJson([
+        imagedCommitJson(1),
+        commitJson(['id' => 'c2', 'images' => [['id' => 'not-web', 'url' => 'file:///etc/passwd']]]),
+    ]))]);
+
+    $screen = Native::visit('/log');
+
+    $screen->call('openImage', 'nope')
+        ->call('openImage', 'c1', 3)
+        ->call('openImage', 'c1', -1)
+        ->tap('image-not-web')
+        ->assertSet('viewerOpen', false)
+        ->assertSet('viewerImages', [])
+        ->assertNativeNotCalled('Browser.OpenInApp');
+});
+
+it('closes on the phone\'s close or back and forgets everything, so the next image opens as this one did', function (string $platform) {
+    $screen = logWithImages(2, platform: $platform);
+
+    $screen->tap('image-i2');
+    $firstPinch = nodeByRef($screen, 'viewer-gestures')['props']['pinch-id'];
+
+    $screen->dismissSheet('image-viewer');
+
+    $viewing = $screen->instance();
+
+    expect($viewing->viewerOpen)->toBeFalse()
+        ->and($viewing->viewerImages)->toBe([])
+        ->and($viewing->viewerIndex)->toBe(0)
+        ->and($viewing->viewerZoom)->toBeNull()
+        ->and($viewing->viewerPanX)->toBeNull()
+        ->and($viewing->viewerPanY)->toBeNull()
+        // The modal itself stays in the tree, hidden, so the phone can animate it away and say when it's gone.
+        ->and(nodeByRef($screen, 'image-viewer')['props']['visible'])->toBeFalse()
+        ->and(findNode($screen->tree(), fn (array $node): bool => ($node['ref'] ?? null) === 'viewed-image'))->toBeNull();
+
+    $screen->tap('image-i1');
+
+    expect(nodeByRef($screen, 'viewed-image')['props']['src'])->toBe('https://img.test/1')
+        // A fresh pinch, seeded at one again, not the one the closed image was using.
+        ->and(nodeByRef($screen, 'viewer-gestures')['props']['pinch-id'])->not->toBe($firstPinch);
+})->with(['ios', 'android']);
+
+it('goes nowhere when the next or previous image is at no web address, so the viewer never shows one', function () {
+    Http::fake(['devnull.test/*' => Http::response(pageJson([commitJson(['id' => 'c1', 'images' => [
+        ['id' => 'i1', 'url' => 'https://img.test/1', 'width' => 10, 'height' => 10],
+        ['id' => 'i2', 'url' => 'file:///etc/passwd', 'width' => 10, 'height' => 10],
+        ['id' => 'i3', 'url' => 'https://img.test/3', 'width' => 10, 'height' => 10],
+    ]])]))]);
+
+    $screen = Native::visit('/log');
+
+    // From the first, next is the unsafe image: the chevron goes nowhere.
+    $screen->tap('image-i1')->tap('viewed-next');
+
+    expect($screen->instance()->viewerIndex)->toBe(0)
+        ->and(nodeByRef($screen, 'viewed-image')['props']['src'])->toBe('https://img.test/1');
+
+    // From the last, previous is the unsafe image: the chevron goes nowhere either.
+    $screen->tap('image-i3')->tap('viewed-previous');
+
+    expect($screen->instance()->viewerIndex)->toBe(2)
+        ->and(nodeByRef($screen, 'viewed-image')['props']['src'])->toBe('https://img.test/3');
+
+    // Nothing the viewer shows is at any but a web address.
+    $shown = findNodes(nodeByRef($screen, 'image-viewer'), fn (array $node): bool => ($node['type'] ?? null) === 'image');
+
+    expect($shown)->not->toBeEmpty()
+        ->and(array_map(fn (array $node): string => $node['props']['src'] ?? '', $shown))->each->toStartWith('https://');
+});
+
+it('keeps the browser for a commit\'s link preview, as before', function () {
+    Http::fake(['devnull.test/*' => Http::response(pageJson([commitJson([
+        'id' => 'c1',
+        'body' => 'Read https://nativephp.com/docs',
+        'link_preview' => ['url' => 'https://nativephp.com/docs', 'title' => 'Docs', 'ready' => true],
+    ])]))]);
+
+    Native::visit('/log')->tap('link-preview-c1')
+        ->assertNativeCalled('Browser.OpenInApp', fn (array $params): bool => $params['url'] === 'https://nativephp.com/docs')
+        ->assertSet('viewerOpen', false);
+});
+
+it('hangs the viewer over every screen that shows commits', function (string $path, array $api) {
+    fakeApi($api);
+
+    $screen = $path === '/profile/starred'
+        ? finishRefreshes(Native::visit($path, platform: 'ios'))
+        : Native::visit($path, platform: 'ios');
+
+    $screen->tap('image-i1');
+
+    expect(nodeByRef($screen, 'image-viewer')['props']['visible'])->toBeTrue()
+        ->and(nodeByRef($screen, 'viewed-image')['props']['src'])->toBe('https://img.test/1');
+
+    $screen->assertNativeNotCalled('Browser.OpenInApp');
+})->with([
+    'a commit\'s page' => ['/log/commits/c1', [
+        'GET /api/v1/commits/c1' => [commitPageJson(commitJson(['id' => 'c1', 'images' => imagedCommitImages()]))],
+        'GET /api/v1/commits/c1/replies' => [pageJson([])],
+    ]],
+    'a profile' => ['/log/users/ada', [
+        'GET /api/v1/users/ada' => [[
+            'data' => userWithCountsJson(['id' => 'u2', 'username' => 'ada'], commits: 1),
+            'is_following' => false,
+            'activity' => ['scale' => 'week', 'buckets' => []],
+            'streaks' => ['longest' => 0, 'current' => 0],
+            'pinned_commit' => null,
+        ]],
+        'GET /api/v1/users/ada/commits' => [pageJson([commitJson(['id' => 'c1', 'author' => userJson(['id' => 'u2', 'username' => 'ada']), 'images' => imagedCommitImages()])])],
+    ]],
+    'the starred page' => ['/profile/starred', [
+        'GET /api/v1/starred' => [pageJson([commitJson(['id' => 'c1', 'starred' => true, 'images' => imagedCommitImages()])], path: 'http://devnull.test/api/v1/starred')],
+    ]],
+]);
+
+it('hangs over the sheet, and leaves a photo being written in the sheet alone, as before', function () {
+    serveApi([
+        'GET /api/v1/log/following' => [pageJson([imagedCommitJson(1)])],
+        'POST /api/v1/commits/preview' => [['data' => ['body' => 'Look at this']]],
+    ]);
+
+    $screen = Native::visit('/log', platform: 'ios');
+
+    // The composer in the sheet, previewing the photo just picked.
+    $screen->press('composeInSheet')
+        ->emitNative(MediaSelected::class, ['success' => true, 'files' => [['path' => testPhoto()]]])
+        ->tap('sheet-preview');
+
+    // The photo being written is the draft's, not a shown commit's, so tapping it opens nothing — in the browser it
+    // opened nothing either.
+    $screen->tap('image-draft-0')
+        ->assertSet('viewerOpen', false)
+        ->assertSet('sheetOpen', true)
+        ->assertNativeNotCalled('Browser.OpenInApp');
+
+    // The viewer hangs beside the sheet in the tree, after it, with the sheet still up underneath — the order the
+    // platforms are given to draw them in. That it truly covers the sheet on a device is left to verify there; this
+    // is what the app can promise from here.
+    $screen->call('openImage', 'c1', 0);
+
+    $refs = [];
+    $collect = function (array $node) use (&$collect, &$refs): void {
+        if (isset($node['ref'])) {
+            $refs[] = $node['ref'];
+        }
+
+        foreach ($node['children'] ?? [] as $child) {
+            $collect($child);
+        }
+    };
+    $collect($screen->tree());
+
+    expect(array_search('image-viewer', $refs, true))->toBeGreaterThan(array_search('sheet', $refs, true))
+        ->and(nodeByRef($screen, 'image-viewer')['props']['visible'])->toBeTrue()
+        ->and($screen->instance()->sheetOpen)->toBeTrue();
+});
diff --git a/tests/Feature/Screens/LogTest.php b/tests/Feature/Screens/LogTest.php
index 3e0d08a..4cae27c 100644
--- a/tests/Feature/Screens/LogTest.php
+++ b/tests/Feature/Screens/LogTest.php
@@ -304,7 +304,10 @@
             && ($node['style']['bg_color'] ?? null) === config('native-ui.theme.light.wash'))
         ->assertElement('image', fn (array $node): bool => ($node['props']['src'] ?? null) === 'http://devnull.test/commit-images/i1')
         ->tap('image-i1')
-        ->assertNativeCalled('Browser.OpenInApp', fn (array $params): bool => $params['url'] === 'http://devnull.test/commit-images/i1');
+        ->assertSet('viewerOpen', true)
+        ->assertElement('image', fn (array $node): bool => ($node['ref'] ?? null) === 'viewed-image'
+            && ($node['props']['src'] ?? null) === 'http://devnull.test/commit-images/i1')
+        ->assertNativeNotCalled('Browser.OpenInApp');
 });
 
 it('lays out several images in the web grid', function () {
@@ -320,7 +323,10 @@
     Native::visit('/log')
         ->assertElement('pressable', fn (array $node): bool => ($node['ref'] ?? null) === 'image-i3' && ($node['a11y']['label'] ?? $node['props']['a11y_label'] ?? null) !== null)
         ->tap('image-i3')
-        ->assertNativeCalled('Browser.OpenInApp', fn (array $params): bool => $params['url'] === 'https://img.test/3');
+        ->assertSet('viewerIndex', 2)
+        ->assertElement('image', fn (array $node): bool => ($node['ref'] ?? null) === 'viewed-image'
+            && ($node['props']['src'] ?? null) === 'https://img.test/3')
+        ->assertNativeNotCalled('Browser.OpenInApp');
 });
 
 it('reads each image out by the description its author gave it, as the web does with alt text', function (array $images, array $labels) {