docs(changelog): link 200ms blocks specification

app/upgrades/changelog/[slug]/ChangeDetailClient.tsx

@@ -113,6 +113,23 @@ export function ChangeDetailClient({ change }: ChangeDetailClientProps) {
                 <Text as="div" variant="body" dangerouslySetInnerHTML={migrationNotesHtml} />
               </div>
             ) : null}
+            {change.specUrl ? (
+              <div>
+                <Text variant="label.medium" tone="muted" className="mb-2">
+                  Specification
+                </Text>
+                <Button
+                  href={change.specUrl}
+                  target="_blank"
+                  rel="noopener noreferrer"
+                  variant="outline"
+                  size="sm"
+                >
+                  Read specification
+                  <ExternalLinkIcon />
+                </Button>
+              </div>
+            ) : null}
             {change.relatedRepos && change.relatedRepos.length > 0 ? (
               <div>
                 <Text variant="label.medium" tone="muted" className="mb-2">

app/upgrades/changelog/[slug]/page.tsx

@@ -58,14 +58,8 @@ export default async function ChangePage(props: ChangePageProps) {
             {change.title}
           </Text>
         </div>
-        <div className="flex shrink-0 flex-wrap gap-2 md:justify-end">
-          {change.specUrl ? (
-            <Button href={change.specUrl} target="_blank" rel="noopener noreferrer" variant="outline" size="sm">
-              Documentation
-              <ExternalLinkIcon />
-            </Button>
-          ) : null}
-          {change.kind === 'eip' ? (
+        {change.kind === 'eip' ? (
+          <div className="flex shrink-0 flex-wrap gap-2 md:justify-end">
             <Button
               href={change.upstreamUrl}
               target="_blank"
@@ -76,8 +70,8 @@ export default async function ChangePage(props: ChangePageProps) {
               Upstream EIP
               <ExternalLinkIcon />
             </Button>
-          ) : null}
-        </div>
+          </div>
+        ) : null}
       </header>
       <ChangeDetailClient change={change} />
     </div>

app/upgrades/data/changes.ts

@@ -351,13 +351,13 @@ export const changes: Change[] = [
       '<p>Base will produce native L2 blocks at a 200ms cadence. Each block has its own number, hash, state root, receipts, and unsafe-to-finalized lifecycle.</p><p class="mt-4">Unlike Flashblocks, which expose sub-second updates while building one block, this change runs the full rollup block lifecycle every 200ms.</p><div class="mt-4 rounded-lg border border-bds-orange-20 border-l-4 border-l-bds-orange-50 bg-bds-orange-5 px-4 py-3"><p class="text-[11px] font-semibold uppercase tracking-wide text-bds-orange-70">Deprecation Notice</p><p class="mt-1"><strong>Flashblocks will be deprecated as part of this release.</strong> Because native 200ms blocks deliver the same sub-second confirmation experience directly on the canonical chain, the Flashblocks WebSocket stream is no longer needed and will be removed. Migrate off the Flashblocks WebSocket stream before Denim activation.</p></div><p class="mt-4">Ethereum block headers and <code>block.timestamp</code> remain in whole seconds. The BaseTime predeploy records the sub-second component before user transactions, while optional <code>timestampMs</code> and <code>blockTimestampMs</code> RPC fields expose the complete millisecond timestamp to applications and infrastructure.</p>',
     migrationNotes:
       '<p><strong>Application developers</strong></p><p class="mt-2 pb-4">Existing contracts and applications remain compatible. Use the BaseTime <code>timestampMs()</code> getter when contracts need same-block millisecond precision; continue using <code>block.timestamp</code> when second-level precision is sufficient.</p><p><strong>RPC and indexing providers</strong></p><p class="mt-2 pb-4">Support the optional <code>timestampMs</code> block and header field and <code>blockTimestampMs</code> on mined transactions and logs. Do not infer millisecond timestamps from the whole-second header value.</p><p><strong>Node operators</strong></p><p class="mt-2">Upgrade to a Denim-compatible release before activation. Plan capacity for the higher native block rate across execution, storage, RPC events, and peer-to-peer propagation.</p>',
-    lastUpdated: '2026-08-10',
+    lastUpdated: '2026-08-24',
     relatedRepos: [
       'https://github.com/base/base',
       'https://github.com/base/contracts/blob/4848ec70d8f1062fec59470d6e731e13ece8a728/src/L2/BaseTime.sol',
     ],
     githubIssues: [],
-    specUrl: '',
+    specUrl: 'https://docs.base.org/base-chain/specs/upgrades/denim/200ms-native-blocks',
   },
 ];
 

app/upgrades/library/upgrades.test.ts

@@ -54,6 +54,7 @@ describe('upgrades route helpers', () => {
       title: '200ms Blocks',
       category: 'execution',
       upgrade: 'denim',
+      specUrl: 'https://docs.base.org/base-chain/specs/upgrades/denim/200ms-native-blocks',
     });
 
     const execution = categoryGroupsForUpgrade('denim').find(