diff --git a/README.md b/README.md
index c629c6f..de90209 100644
--- a/README.md
+++ b/README.md
@@ -119,16 +119,22 @@ The metric whitelist lives in `InstagramGraphAPI::Metrics`:
 ```ruby
 InstagramGraphAPI::Metrics::MEDIA_INSIGHT_METRICS[:reel]
 # => ["reach", "likes", "comments", "shares", "saved", "total_interactions",
-#     "plays", "views", "ig_reels_avg_watch_time", "ig_reels_video_view_total_time"]
+#     "views", "ig_reels_avg_watch_time", "ig_reels_video_view_total_time"]
 
 InstagramGraphAPI::Metrics::ACCOUNT_INSIGHT_METRICS
 # => ["views", "profile_views", "follower_count", "accounts_engaged",
 #     "total_interactions", "reach", "likes", "comments", "shares", "saves"]
 ```
 
-Deprecated names (`impressions`, `engagement`, `video_views`) are
-intentionally absent — the Graph v21 schema renamed/retired them in
-2024–2025.
+Deprecated names (`impressions`, `engagement`, `video_views`, `plays`,
+`exits`) are intentionally absent — the Graph schema renamed or retired
+them between 2024 and 2026.
+
+Keep the list narrow. The API validates the whole `metric` list before it
+reads any of it, so a single retired name answers 400 for the request and
+costs every metric for that media kind. When one is rejected the error
+names every value the API will accept, which is the list to widen
+against.
 
 ### Comments + replies
 
diff --git a/lib/instagram_graph_api/metrics.rb b/lib/instagram_graph_api/metrics.rb
index ab2ebc8..fc56f66 100644
--- a/lib/instagram_graph_api/metrics.rb
+++ b/lib/instagram_graph_api/metrics.rb
@@ -1,19 +1,34 @@
 # frozen_string_literal: true
 
 module InstagramGraphAPI
-  # Whitelist of insight metric names the Instagram Graph API (v21+)
-  # returns for each media kind. Names that Meta retired during the 2024
-  # and 2025 schema cleanups — `impressions`, `engagement`,
-  # `video_views` — are intentionally absent. `plays` is still supported
-  # for feed videos and reels in v21+ and is included accordingly.
+  # Whitelist of insight metric names the Instagram Graph API returns for
+  # each media kind. Names that Meta retired during the 2024 and 2025
+  # schema cleanups — `impressions`, `engagement`, `video_views`,
+  # `plays` — are intentionally absent.
+  #
+  # A rejected name fails the whole request, not just its own column: the
+  # API validates the metric list up front and answers 400 for all of it.
+  # One retired name therefore costs every metric for that media kind, so
+  # this list is only ever widened against a verified response.
+  #
+  # `plays` was dropped 2026-09-20. It had been kept on video and reel on
+  # the belief that v21 still served it; production rejects it with
+  # `metric[6] must be one of the following values: ...`, and that list
+  # does not contain it. Video takes `views` in its place, verified
+  # against a real feed video on the same call. The same error names
+  # every metric the API will accept, and `exits` is absent from it too,
+  # which is why the story set no longer asks for it.
   #
   # Consumed by the Rails ingestion layer in phase 5b.
   module Metrics
     MEDIA_INSIGHT_METRICS = {
       image:    %w[reach likes comments shares saved total_interactions].freeze,
-      video:    %w[reach likes comments shares saved total_interactions plays].freeze,
-      reel:     %w[reach likes comments shares saved total_interactions plays views ig_reels_avg_watch_time ig_reels_video_view_total_time].freeze,
-      story:    %w[reach replies exits views].freeze,
+      video:    %w[reach likes comments shares saved total_interactions views].freeze,
+      reel:     %w[reach likes comments shares saved total_interactions views ig_reels_avg_watch_time ig_reels_video_view_total_time].freeze,
+      # `navigation` is what replaced `exits`, but it reports through a
+      # breakdown this client does not ask for yet, so it is left out
+      # until a live story can be used to check the shape that comes back.
+      story:    %w[reach replies views].freeze,
       carousel: %w[reach likes comments shares saved total_interactions views].freeze
     }.freeze
 
diff --git a/spec/instagram_graph_api/metrics_spec.rb b/spec/instagram_graph_api/metrics_spec.rb
index 307a54a..c0bf571 100644
--- a/spec/instagram_graph_api/metrics_spec.rb
+++ b/spec/instagram_graph_api/metrics_spec.rb
@@ -19,22 +19,30 @@
     end
 
     it 'uses story-specific metrics' do
-      expect(described_class::MEDIA_INSIGHT_METRICS[:story]).to match_array(%w[reach replies exits views])
+      expect(described_class::MEDIA_INSIGHT_METRICS[:story]).to match_array(%w[reach replies views])
     end
 
     it 'excludes metrics deprecated in the 2024-2025 Graph schema' do
       all_metrics = described_class::MEDIA_INSIGHT_METRICS.values.flatten.uniq
       expect(all_metrics).not_to include('impressions') # retired across all media kinds
       expect(all_metrics).not_to include('engagement')  # retired
-      expect(all_metrics).not_to include('video_views') # renamed → `views`/`plays`
+      expect(all_metrics).not_to include('video_views') # renamed → `views`
     end
 
-    it 'keeps `plays` on the kinds where Graph v21 still supports it' do
-      expect(described_class::MEDIA_INSIGHT_METRICS[:video]).to include('plays')
-      expect(described_class::MEDIA_INSIGHT_METRICS[:reel]).to include('plays')
-      %i[image story carousel].each do |kind|
-        expect(described_class::MEDIA_INSIGHT_METRICS[kind]).not_to include('plays')
-      end
+    # A retired name is not a missing column, it is a 400 for the whole
+    # request. While `plays` sat in the video list, every feed video and
+    # every reel published through the app recorded no insights at all,
+    # and the ingestion job logged the failure and moved on. `exits` was
+    # doing the same to stories.
+    it 'asks for no metric the API has retired out from under it' do
+      all_metrics = described_class::MEDIA_INSIGHT_METRICS.values.flatten.uniq
+      expect(all_metrics).not_to include('plays')
+      expect(all_metrics).not_to include('exits')
+    end
+
+    it 'counts video plays as `views`, the name that replaced them' do
+      expect(described_class::MEDIA_INSIGHT_METRICS[:video]).to include('views')
+      expect(described_class::MEDIA_INSIGHT_METRICS[:reel]).to include('views')
     end
   end