diff --git a/devplacepy/static/css/attachments.css b/devplacepy/static/css/attachments.css
index 4a180982..3f7fcd9e 100644
--- a/devplacepy/static/css/attachments.css
+++ b/devplacepy/static/css/attachments.css
@@ -29,6 +29,23 @@
     max-height: 200px;
 }
 
+.attachment-gallery.single .attachment-gallery-item:has(.gallery-thumb) {
+    width: 100%;
+    max-width: 100%;
+}
+
+.attachment-gallery.single .attachment-gallery-item:has(.gallery-thumb):hover {
+    transform: none;
+    border-color: var(--border-light);
+}
+
+.attachment-gallery.single .gallery-thumb {
+    width: 100%;
+    max-width: 100%;
+    max-height: 480px;
+    object-fit: contain;
+}
+
 .attachment-gallery-item:has(.non-image) {
     width: 120px;
     height: 120px;
diff --git a/devplacepy/static/js/CLAUDE.md b/devplacepy/static/js/CLAUDE.md
index 0fc87154..752e9654 100644
--- a/devplacepy/static/js/CLAUDE.md
+++ b/devplacepy/static/js/CLAUDE.md
@@ -92,7 +92,11 @@ File validation: max 5MB, allowed extensions: `.png`, `.jpg`, `.jpeg`, `.gif`, `
 
 **Ingesting a file from a URL.** `store_attachment_from_url(url, user_uid, filename=None)` (async, in `attachments.py`) is the remote counterpart to `store_attachment`: it downloads the URL on the server through `fetch_remote_file()` - SSRF-guarded (`_guard_public_url` resolves the host and refuses private/loopback/reserved/multicast addresses, mirroring the Devii fetch guard) and size-capped (streams, aborting once `_get_max_upload_bytes()` is exceeded) - resolves a filename from the URL path or the response `Content-Type` (`MIME_TO_EXT`), then calls `store_attachment()` so the bytes land in the **exact same** pipeline (validation, thumbnailing, DB row). It raises `RemoteFetchError(message, status)` which the route maps to an HTTP status. It is exposed at `POST /uploads/upload-url` (`UploadUrlForm{url, filename?}`, `require_user_api`) and as the Devii catalog action `attach_url` (handler `http`, `requires_auth=True`); both return the same record as `/uploads/upload`. The returned `uid` binds to a resource the same way as any upload - via `attachment_uids` at create/edit time - so attaching a remote image is just `attach_url` then `create_post`/`create_project`/etc. with that uid. Do not re-download remote files in a router; reuse this helper so the guard and size cap stay in one place.
 
-`_row_to_attachment()` / `store_attachment()` expose `is_image` and `is_video` (derived from the mime prefix). The shared partial `templates/_attachment_display.html` branches image -> `<img>`, video -> `<video controls preload="metadata" class="gallery-video">`, else download link; rendering through this one partial is what makes video work across every feature at once. `AttachmentOut` (`schemas.py`) carries both flags - add new display keys there too or JSON drops them.
+`_row_to_attachment()` / `store_attachment()` expose `is_image` and `is_video` (derived from the mime prefix). The shared partial `templates/_attachment_display.html` branches image -> `<img>`, video -> `<video controls preload="metadata" class="gallery-video">`, else download link; rendering through this one partial is what makes video work across every feature at once.
+
+**Every caller MUST bind `attachments` before including the partial** - `{% set attachments = item.get('attachments', []) %}` or `{% with attachments=... %}`. The partial iterates the bare name `attachments`, so a caller that only guards on `{% if item.attachments %}` and includes without binding renders the gallery from whatever `attachments` happens to be in the surrounding page context. This is not theoretical: `_post_card.html` did exactly that, so **feed and profile cards silently rendered an empty gallery for every post that had an image**, and on a project page (where `project_detail.html` sets `attachments` at template scope for the project's own files) a devlog card would have rendered the *project's* attachments as if they were the post's. Guarded by `tests/e2e/feed.py::test_feed_card_shows_the_post_image`.
+
+**A lone attachment is a hero, not a chip.** When the gallery holds exactly one item the partial adds a `single` class, and `attachments.css` widens that item to the full content column (`max-height: 480px`, `object-fit: contain`, no hover scale) instead of the 240x200 chip a multi-item gallery uses. **The `single` branch must serve `att['url']`, never `thumbnail_url`** - a thumbnail is 200px on its longest side, so blowing it up to the column width renders visibly blurry. That is the whole reason the src is a conditional rather than "thumbnail when one exists". Because the partial is shared, this applies everywhere at once: post cards, post detail, comments, gists, projects and chat bubbles. Animated GIFs never had a thumbnail to begin with (`THUMBNAIL_EXTENSIONS` excludes `.gif`, so animation survives), which means they already took the original-file path and simply render larger now. `AttachmentOut` (`schemas.py`) carries both flags - add new display keys there too or JSON drops them.
 
 Media is served **inline** (not forced-download) for known-safe types only. The set `INLINE_MEDIA_EXTENSIONS` in `main.py` (`UploadStaticFiles`) and the matching `map $uri $upload_disposition` in `nginx/nginx.conf.template` must stay in sync: images/video/audio -> `inline` (so `<video>` plays and seeks via Range), everything else -> `attachment`. SVG is deliberately excluded from both (stored-XSS defense). `ContentRenderer.js` embeds direct video URLs typed into content via `videoExtRe`, mirroring its image handling.
 
diff --git a/devplacepy/templates/_attachment_display.html b/devplacepy/templates/_attachment_display.html
index 3d6596d2..21af6b15 100644
--- a/devplacepy/templates/_attachment_display.html
+++ b/devplacepy/templates/_attachment_display.html
@@ -1,10 +1,9 @@
-<div class="attachment-gallery">
+{% set _single = attachments|length == 1 %}
+<div class="attachment-gallery{% if _single %} single{% endif %}">
     {% for att in attachments %}
     <div class="attachment-gallery-item">
-        {% if att.get('is_image') and att.get('thumbnail_url') %}
-        <img src="{{ att['thumbnail_url'] }}" alt="{{ att.get('original_filename', '') }}" loading="lazy" class="gallery-thumb" data-lightbox data-full="{{ att['url'] }}" data-mime="{{ att.get('mime_type', '') }}">
-        {% elif att.get('is_image') %}
-        <img src="{{ att['url'] }}" alt="{{ att.get('original_filename', '') }}" loading="lazy" class="gallery-thumb" data-lightbox data-full="{{ att['url'] }}" data-mime="{{ att.get('mime_type', '') }}">
+        {% if att.get('is_image') %}
+        <img src="{{ att['url'] if _single or not att.get('thumbnail_url') else att['thumbnail_url'] }}" alt="{{ att.get('original_filename', '') }}" loading="lazy" class="gallery-thumb" data-lightbox data-full="{{ att['url'] }}" data-mime="{{ att.get('mime_type', '') }}">
         {% elif att.get('is_video') %}
         <video src="{{ att['url'] }}" controls preload="metadata" class="gallery-video"></video>
         {% elif att.get('is_audio') %}
diff --git a/devplacepy/templates/_post_card.html b/devplacepy/templates/_post_card.html
index 009f7239..a419d55c 100644
--- a/devplacepy/templates/_post_card.html
+++ b/devplacepy/templates/_post_card.html
@@ -25,7 +25,8 @@
     <a href="{{ item.project_link.url }}" class="project-link">Project: {{ item.project_link.name }}</a>
     {% endif %}
 
-    {% if item.attachments %}
+    {% set attachments = item.get('attachments', []) %}
+    {% if attachments %}
     {% include "_attachment_display.html" %}
     {% endif %}
 
diff --git a/tests/conftest.py b/tests/conftest.py
index 30f95638..e2c63464 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -319,6 +319,23 @@ def login_user(page, user):
     page.wait_for_url("**/feed", timeout=10000, wait_until="domcontentloaded")
 
 
+def create_post_with_files(page, content, files, expected_count=1):
+    from playwright.sync_api import expect
+
+    page.goto(f"{BASE_URL}/feed", wait_until="domcontentloaded")
+    page.locator(".feed-fab").first.wait_for(state="visible", timeout=10000)
+    page.locator(".feed-fab").first.click()
+    page.fill("#post-content", content)
+    page.locator("#create-post-modal dp-upload .dp-upload-input").first.set_input_files(
+        files
+    )
+    expect(
+        page.locator("#create-post-modal dp-upload .dp-upload-count").first
+    ).to_have_text(f"({expected_count})", timeout=15000)
+    page.locator("#create-post-modal button.btn-primary:has-text('Post')").click()
+    page.wait_for_url(f"{BASE_URL}/posts/*", wait_until="domcontentloaded")
+
+
 def assert_share_copies(page, expected_fragment):
     from playwright.sync_api import expect
 
diff --git a/tests/e2e/feed.py b/tests/e2e/feed.py
index 0b4072f7..a52fb4c0 100644
--- a/tests/e2e/feed.py
+++ b/tests/e2e/feed.py
@@ -1,6 +1,6 @@
 # retoor <retoor@molodetz.nl>
 
-from tests.conftest import BASE_URL
+from tests.conftest import BASE_URL, create_post_with_files
 import time
 import requests
 from playwright.sync_api import expect
@@ -702,6 +702,28 @@ def test_feed_politics_topic(alice):
     assert politics_link.is_visible()
 
 
+def test_feed_card_shows_the_post_image(alice):
+    import io
+    from PIL import Image
+
+    page, _ = alice
+    buf = io.BytesIO()
+    Image.new("RGB", (600, 400), (28, 120, 200)).save(buf, "PNG")
+    create_post_with_files(
+        page,
+        "Feed card image rendering check",
+        [{"name": "card.png", "mimeType": "image/png", "buffer": buf.getvalue()}],
+    )
+    page.goto(f"{BASE_URL}/feed", wait_until="domcontentloaded")
+    card = page.locator(
+        ".post-card:has-text('Feed card image rendering check')"
+    ).first
+    card.wait_for(state="visible", timeout=10000)
+    image = card.locator(".attachment-gallery.single .gallery-thumb").first
+    image.wait_for(state="visible", timeout=10000)
+    assert "_thumb" not in image.get_attribute("src")
+
+
 def test_create_post_cancel_modal(alice):
     page, _ = alice
     page.goto(f"{BASE_URL}/feed", wait_until="domcontentloaded")
diff --git a/tests/e2e/post.py b/tests/e2e/post.py
index 814c1b92..822f1f00 100644
--- a/tests/e2e/post.py
+++ b/tests/e2e/post.py
@@ -2,7 +2,7 @@
 
 import re
 from playwright.sync_api import expect
-from tests.conftest import BASE_URL, assert_share_copies
+from tests.conftest import BASE_URL, assert_share_copies, create_post_with_files
 def create_post(page, topic="random", content="Test post content", title=None):
     page.goto(f"{BASE_URL}/feed", wait_until="domcontentloaded")
     page.locator(".feed-fab").first.wait_for(state="visible", timeout=10000)
@@ -13,6 +13,27 @@ def create_post(page, topic="random", content="Test post content", title=None):
         page.fill("#post-title", title)
     page.locator("#create-post-modal button.btn-primary:has-text('Post')").click()
     page.wait_for_url(f"{BASE_URL}/posts/*", wait_until="domcontentloaded")
+def _png_bytes(color=(0, 128, 255), size=(600, 400)):
+    import io
+    from PIL import Image
+
+    buf = io.BytesIO()
+    Image.new("RGB", size, color).save(buf, "PNG")
+    return buf.getvalue()
+
+
+def _gif_bytes():
+    import io
+    from PIL import Image
+
+    frames = [Image.new("RGB", (40, 40), c) for c in ((255, 0, 0), (0, 0, 255))]
+    buf = io.BytesIO()
+    frames[0].save(
+        buf, "GIF", save_all=True, append_images=frames[1:], duration=120, loop=0
+    )
+    return buf.getvalue()
+
+
 def _profile_stars(page, username):
     page.goto(f"{BASE_URL}/profile/{username}", wait_until="domcontentloaded")
     value = page.locator(
@@ -375,6 +396,57 @@ def test_emoji_picker_opens(alice):
     assert page.locator("emoji-picker").first.is_visible()
 
 
+def test_single_image_post_shows_the_original_full_size(alice):
+    page, _ = alice
+    create_post_with_files(
+        page,
+        "Post carrying exactly one image",
+        [{"name": "shot.png", "mimeType": "image/png", "buffer": _png_bytes()}],
+    )
+    gallery = page.locator(".attachment-gallery.single")
+    gallery.wait_for(state="visible", timeout=10000)
+    img = gallery.locator(".gallery-thumb").first
+    src = img.get_attribute("src")
+    assert "_thumb" not in src, f"hero image served the 200px thumbnail: {src}"
+    assert src == img.get_attribute("data-full")
+
+
+def test_multiple_image_post_keeps_thumbnails(alice):
+    page, _ = alice
+    create_post_with_files(
+        page,
+        "Post carrying two images",
+        [
+            {"name": "one.png", "mimeType": "image/png", "buffer": _png_bytes()},
+            {
+                "name": "two.png",
+                "mimeType": "image/png",
+                "buffer": _png_bytes((200, 30, 90)),
+            },
+        ],
+        expected_count=2,
+    )
+    page.locator(".attachment-gallery").first.wait_for(state="visible", timeout=10000)
+    assert page.locator(".attachment-gallery.single").count() == 0
+    thumbs = page.locator(".attachment-gallery .gallery-thumb")
+    assert thumbs.count() == 2
+    for i in range(thumbs.count()):
+        assert "_thumb" in thumbs.nth(i).get_attribute("src")
+
+
+def test_animated_gif_post_serves_the_original_file(alice):
+    page, _ = alice
+    create_post_with_files(
+        page,
+        "Post carrying an animated gif",
+        [{"name": "loop.gif", "mimeType": "image/gif", "buffer": _gif_bytes()}],
+    )
+    img = page.locator(".attachment-gallery .gallery-thumb").first
+    img.wait_for(state="visible", timeout=10000)
+    src = img.get_attribute("src")
+    assert src.endswith(".gif"), f"animation lost, served {src}"
+
+
 def test_attachment_upload_ui(alice):
     import io
     from PIL import Image