feat: cache stats dashboard card expansion

CHANGELOG.md

@@ -9,7 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
-- Cache entry detail page — `GET /cache/entries/:id` shows the full key, byte size, and created-at for a single entry; value body is gated behind `SolidStackWeb.allow_value_preview` (default `false`); when enabled, displays up to 4 KB of the raw serialized value with a truncation notice; entry key in the browser table is now a link to the detail page; **Delete** button on the detail page redirects back to the entry list
+- Cache stats dashboard card — adds **Oldest** entry age (via `time_ago_in_words` with exact timestamp on hover) to the Solid Cache overview card; stat is hidden when the cache is empty; **Entries** count is now a link to the entry browser; `oldest_entry` added to the `/metrics` JSON payload as ISO 8601 (or `null`)
+- Cache entry detail page — `GET /cache/entries/:id` shows the full key, byte size, and created-at for a single entry; value body is gated behind `SolidStackWeb.allow_value_preview` (default `false`); when enabled, displays up to 4 KB with JSON pretty-printing and a format badge (JSON / Text); entry key in the browser table is now a link to the detail page; **Delete** button on the detail page redirects back to the entry list
 - Solid Cache entry browser — `GET /cache/entries` lists all `SolidCache::Entry` records in a paginated, sortable table (key, byte size, created-at); sortable by any column; key-substring search filters the list; per-row **Delete** removes a single entry; **Flush All** header button deletes every entry with a confirmation prompt; Cache subnav (Overview / Entries) added to the layout
 
 ## [0.4.0] - 2026-05-26

README.md

@@ -100,7 +100,7 @@ Filters are preserved when switching between status tabs (Ready / Scheduled / Ru
 
 ### Features
 
-- **Overview dashboard card** — live entry count and total byte size
+- **Overview dashboard card** — live entry count (linked to the entry browser), total byte size, and oldest-entry age (`time_ago_in_words` with exact timestamp on hover; hidden when cache is empty)
 - **Entry browser** — `GET /cache/entries` lists all `SolidCache::Entry` records in a paginated, sortable table; columns: key, byte size, created-at; sortable by any column; key auto-submits search after 4 characters
 - **Key search** — filter entries by key substring; results update automatically after 4 characters
 - **Entry detail page** — `GET /cache/entries/:id` shows the full key, byte size, and created-at; optionally displays the raw serialized value (see `allow_value_preview` below)
@@ -133,7 +133,7 @@ _Channel monitoring coming in v0.6.0. Currently shows active message count and d
     "processes_stale": 0,
     "slow_jobs": 7
   },
-  "cache": { "entries": 1024, "byte_size": 2097152 },
+  "cache": { "entries": 1024, "byte_size": 2097152, "oldest_entry": "2026-05-20T10:00:00Z" },
   "cable": { "messages": 50, "channels": 3 },
   "generated_at": "2026-05-26T10:00:00Z"
 }

ROADMAP.md

@@ -13,7 +13,6 @@ The path to v1.0.0 is staged: first achieve feature parity with `solid_queue_das
 ### Added
 - **Size distribution stats** — top-N entries by byte size; histogram bucketed by size range
 - **Cache timeline** — 24-hour chart of entry count and total byte size growth
-- **Stats dashboard card** — expand the overview card to include hit/miss rates if `SolidCache` exposes them, plus oldest-entry age
 
 ---
 

app/assets/stylesheets/solid_stack_web/_07_dashboard.css

@@ -69,6 +69,7 @@ a.sqw-inline-stat:hover { opacity: 0.7; text-decoration: none; }
 }
 
 .sqw-inline-stat__value { font-size: 28px; font-weight: 700; line-height: 1; }
+.sqw-inline-stat__value--sm { font-size: 16px; }
 
 .sqw-inline-stat--ready     .sqw-inline-stat__value { color: var(--success); }
 .sqw-inline-stat--scheduled .sqw-inline-stat__value { color: var(--info); }

app/models/solid_stack_web/cache_stats.rb

@@ -2,8 +2,9 @@ module SolidStackWeb
   class CacheStats
     def to_h
       {
-        entries:   ::SolidCache::Entry.count,
-        byte_size: ::SolidCache::Entry.sum(:byte_size)
+        entries:      ::SolidCache::Entry.count,
+        byte_size:    ::SolidCache::Entry.sum(:byte_size),
+        oldest_entry: ::SolidCache::Entry.minimum(:created_at)
       }
     end
   end

app/views/solid_stack_web/cache/index.html.erb

@@ -3,10 +3,10 @@
 </div>
 
 <div class="sqw-stats-grid">
-  <div class="sqw-stat sqw-stat--cache">
+  <%= link_to cache_entries_path, class: "sqw-stat sqw-stat--cache" do %>
     <span class="sqw-stat__label">Total Entries</span>
     <span class="sqw-stat__value"><%= @total_entries %></span>
-  </div>
+  <% end %>
   <div class="sqw-stat sqw-stat--cache">
     <span class="sqw-stat__label">Total Size</span>
     <span class="sqw-stat__value"><%= number_to_human_size(@total_byte_size) %></span>

app/views/solid_stack_web/dashboard/index.html.erb

@@ -76,14 +76,20 @@
       <%= link_to "View Cache →", cache_path, class: "sqw-gem-card__link" %>
     </div>
     <div class="sqw-gem-card__body">
-      <div class="sqw-inline-stat sqw-inline-stat--cache">
+      <%= link_to cache_entries_path, class: "sqw-inline-stat sqw-inline-stat--cache" do %>
         <span class="sqw-inline-stat__label">Entries</span>
         <span class="sqw-inline-stat__value"><%= @cache_stats[:entries] %></span>
-      </div>
+      <% end %>
       <div class="sqw-inline-stat sqw-inline-stat--cache">
         <span class="sqw-inline-stat__label">Size</span>
         <span class="sqw-inline-stat__value"><%= number_to_human_size(@cache_stats[:byte_size]) %></span>
       </div>
+      <% if @cache_stats[:oldest_entry] %>
+        <div class="sqw-inline-stat sqw-inline-stat--cache">
+          <span class="sqw-inline-stat__label">Oldest</span>
+          <span class="sqw-inline-stat__value sqw-inline-stat__value--sm" title="<%= @cache_stats[:oldest_entry].strftime("%b %d, %Y %H:%M") %>"><%= time_ago_in_words(@cache_stats[:oldest_entry]) %></span>
+        </div>
+      <% end %>
     </div>
   </div>
 

spec/requests/solid_stack_web/dashboard_spec.rb

@@ -86,5 +86,17 @@
     ensure
       SolidStackWeb.slow_job_threshold = nil
     end
+
+    it "shows oldest cache entry age when entries exist" do
+      SolidCache::Entry.write("dashboard:key", "v")
+      get engine_root
+      expect(response.body).to include("Oldest")
+    end
+
+    it "omits oldest cache entry stat when no entries exist" do
+      SolidCache::Entry.delete_all
+      get engine_root
+      expect(response.body).not_to include("Oldest")
+    end
   end
 end

spec/requests/solid_stack_web/metrics_spec.rb

@@ -26,7 +26,21 @@
     it "includes cache keys" do
       get "#{engine_root}/metrics"
       cache = JSON.parse(response.body)["cache"]
-      expect(cache.keys).to contain_exactly("entries", "byte_size")
+      expect(cache.keys).to contain_exactly("entries", "byte_size", "oldest_entry")
+    end
+
+    it "includes oldest_entry as ISO 8601 when entries exist" do
+      SolidCache::Entry.write("metrics:key", "v")
+      get "#{engine_root}/metrics"
+      cache = JSON.parse(response.body)["cache"]
+      expect(cache["oldest_entry"]).to match(/\d{4}-\d{2}-\d{2}T/)
+    end
+
+    it "includes oldest_entry as null when no entries exist" do
+      SolidCache::Entry.delete_all
+      get "#{engine_root}/metrics"
+      cache = JSON.parse(response.body)["cache"]
+      expect(cache["oldest_entry"]).to be_nil
     end
 
     it "includes cable keys" do