feat(api): expose isShort on list items

Three parsers know for certain that an item is a Short and then discard the fact:

- `ShortsLockupViewModelParser` and `ReelItemRendererParser` only ever run on a
  shorts renderer, so every item they produce is a Short by construction.
- `VideoRendererParser` reads a thumbnail overlay whose text is the literal
  "SHORTS" in place of a duration. Its own TODO asks for this: "Add some sort of
  metadata for the type of video (normal, live, premiere, shorts)".

All three emit `VideoBadges::None`, so nothing downstream can tell a Short from a
normal video. What makes that costly is the duration: YouTube no longer reports a
real one for Shorts and these parsers substitute an approximate 60s (as their own
NOTE says), so the only signals left to a client are a length indistinguishable
from a genuine 60-second upload, and a "#shorts" title tag that is a convention
rather than metadata. Measured: all 48 items on a channel's Shorts tab report
exactly `lengthSeconds: 60`, and on a live search 4 of 20 results carried
"#shorts" while running 8-27 minutes.

Add a `Shorts` badge, set it in all three parsers, and serialise it as `isShort`
alongside the existing `isUpcoming` / `isNew` / `is4k` flags. `Shorts` is appended
to the flags enum rather than inserted, since these are bit values and reordering
would change the meaning of an already-persisted badge set.

AI disclosure, per AI_POLICY.md: this patch was written with AI assistance.
Exact model: Claude Opus 5, model ID `claude-opus-5[1m]`. Tool used to interact
with it: Claude Code, Anthropic's agentic CLI. The change was verified against a
live patched instance (see the PR for the measurements) and is running in
production on the submitter's instance. Submitted by and the responsibility of
@mdbraber.

src/invidious/helpers/serialized_yt_data.cr

@@ -9,6 +9,9 @@ enum VideoBadges
   VR180
   VR360
   ClosedCaptions
+  # Appended rather than inserted: these are @[Flags] bit values, and reordering
+  # would silently change the meaning of any already-stored badge set.
+  Shorts
 end
 
 struct SearchVideo
@@ -133,6 +136,11 @@ struct SearchVideo
       json.field "isVr360", self.badges.vr360?
       json.field "is3d", self.badges.three_d?
       json.field "hasCaptions", self.badges.closed_captions?
+      # Whether YouTube served this as a Short. Worth stating outright: the
+      # duration cannot be used to infer it, because YouTube no longer reports a
+      # real one for Shorts and the parsers substitute an approximate 60s — so a
+      # genuine 60-second upload is otherwise indistinguishable from a Short.
+      json.field "isShort", self.badges.shorts?
     end
   end
 

src/invidious/yt_backend/extractors.cr

@@ -156,6 +156,18 @@ private module Parsers
         end
       end
 
+      # A Short is marked by the thumbnail's time-status overlay, which carries
+      # the literal text "SHORTS" where a duration would be. The length branch
+      # above already special-cases it — approximating 60s, because YouTube no
+      # longer reports a real duration for Shorts — but then discards the *fact*,
+      # leaving clients to re-derive it from that approximated length or from a
+      # "#shorts" title tag. Neither works: a genuine 60-second upload looks
+      # identical, and the tag is only a convention.
+      is_shorts_overlay = item_contents["thumbnailOverlays"]?.try &.as_a.any? do |overlay|
+        overlay.dig?("thumbnailOverlayTimeStatusRenderer", "text", "simpleText").try &.as_s == "SHORTS"
+      end
+      badges |= VideoBadges::Shorts if is_shorts_overlay
+
       SearchVideo.new({
         title:              title,
         id:                 video_id,
@@ -609,6 +621,8 @@ private module Parsers
 
       duration = (minutes*60 + seconds)
 
+      # Shorts is certain here rather than inferred: this parser only ever runs
+      # on a reel renderer, which YouTube uses exclusively for Shorts.
       SearchVideo.new({
         title:              title,
         id:                 video_id,
@@ -621,7 +635,7 @@ private module Parsers
         premiere_timestamp: Time.unix(0),
         author_verified:    false,
         author_thumbnail:   nil,
-        badges:             VideoBadges::None,
+        badges:             VideoBadges::Shorts,
       })
     end
 
@@ -872,6 +886,10 @@ private module Parsers
       # TODO: Maybe use -1 as an error value and handle that on the frontend?
       duration = 60_i32
 
+      # Shorts is certain here rather than inferred: this parser only ever runs
+      # on a shorts renderer. Without the badge, the approximated 60s above is
+      # the only hint a client has left, and it cannot be told apart from a real
+      # 60-second upload.
       SearchVideo.new({
         title:              title,
         id:                 video_id,
@@ -884,7 +902,7 @@ private module Parsers
         premiere_timestamp: Time.unix(0),
         author_verified:    false,
         author_thumbnail:   nil,
-        badges:             VideoBadges::None,
+        badges:             VideoBadges::Shorts,
       })
     end