diff --git a/README.md b/README.md
index c0e8110..6edbdfa 100644
--- a/README.md
+++ b/README.md
@@ -20,7 +20,7 @@ build, so the template never becomes an incident.
 id: controller-saving-down            # stable, and what dismissal is keyed on — see below
 severity: outage                      # info | warning | outage
 title: Controller saving is down
-summary: One or two sentences. Shown in the dashboard banner and the overlay's support panel.
+summary: The symptom first, in a sentence that stands alone — see below
 workaround: One line on what the reader can do right now. Optional.
 links:                                # optional, up to 5, all https
   - label: PlanetScale status
@@ -50,6 +50,25 @@ against the PR — has to pass before it can merge. Merging then runs the **Depl
 the build fails, nothing is deployed and the previous version stays live** — which is also why the
 build is worth running before you push.
 
+### Writing a summary
+
+The summary travels further than anything else in the file, and the surface that reaches the most
+people shows the least of it. In the dashboard it is a toast: the title, then about three lines of
+summary on desktop and two on a phone, clamped, with the rest a press away. The alert panel, the
+"Report a Bug" interstitial, the card on this site and the overlay's support panel all show it
+whole.
+
+So lead with the symptom, in one sentence that stands on its own — what breaks, and where someone
+sees it. Use the rest for what that sentence earns. Past about 200 characters the build says so,
+as a note rather than a failure, because nothing about prose length should hold up a status page
+mid-incident.
+
+Two things don't belong in it:
+
+- **The workaround.** Every surface that shows the summary renders `workaround` directly beneath
+  it, so a fix written into both reads twice.
+- **The long version.** That is what the body is for, and it is the one field with no limit.
+
 ### When something is actually on fire
 
 Repository admins can still push straight to `main`, and that is deliberate: this site exists to
@@ -106,10 +125,15 @@ Don't bother putting a CDN in front of this to speed it up; there is nothing to
 
 | Reader | What it shows |
 | --- | --- |
-| Dashboard banner | The loudest active alert, with its workaround and first link |
+| Dashboard toast | The loudest active alert: its title, and the first two or three lines of its summary |
+| Dashboard alert panel | That same alert whole — summary, workaround and every link — one press from the toast |
 | Dashboard "Report a Bug" | Every active alert, before the bug tracker opens |
 | Overlay support panel | Every active alert, as health checks, and in the copied report |
 
+A phone's toast opens the panel, since sending someone to another tab mid-task is too much. On
+desktop it links here instead when the incident has a page of its own, and opens the panel when it
+does not.
+
 `alerts.json` is `{ "schema": "gpv-status/1", "alerts": [...] }`, and it carries only what a reader
 could act on: every incident still open or still to come, plus anything resolved in the last 30 days.
 The archive grows on the index page instead, which keeps every incident forever — no reason to make
diff --git a/build.mjs b/build.mjs
index da00901..4d55f5f 100644
--- a/build.mjs
+++ b/build.mjs
@@ -47,6 +47,16 @@ const SEVERITY_LABEL = { info: 'Info', warning: 'Warning', outage: 'Outage' };
 
 const LIMITS = { title: 120, summary: 500, workaround: 200, id: 64, label: 60, links: 5 };
 
+/**
+ * Roughly how much of a summary the dashboard's toast shows: it clamps to three lines on desktop
+ * and two on a phone. Past this a summary is still shown whole everywhere else — the alert panel,
+ * the "Report a Bug" interstitial, the overlay's support panel and the card on this site — but the
+ * toast is where most people meet an incident, so a summary that needs its second half to make
+ * sense is one most readers will only half read. A note rather than a failure: nothing about prose
+ * length should hold up a status page mid-incident.
+ */
+const SUMMARY_CLAMPED_AT = 200;
+
 /**
  * How long a resolved incident stays in alerts.json. Nothing reading the feed ever shows a resolved
  * alert — the dashboard and the overlay both check the window themselves — so this is slack for a
@@ -59,10 +69,21 @@ const FEED_RESOLVED_DAYS = 30;
 const MAX_FEED_ALERTS = 50;
 
 const problems = [];
+const notes = [];
 
 /** Collects every problem rather than stopping at the first, so one run tells you all of them. */
 const fail = (file, message) => problems.push(`${file}: ${message}`);
 
+/** Worth saying, but never worth refusing to publish over. Printed once the run is done. */
+const note = (file, message) => notes.push(`${file}: ${message}`);
+
+const printNotes = () => {
+  if (notes.length === 0) return;
+  console.warn('\nWorth a look, though none of this stopped the build:\n');
+  for (const message of notes) console.warn(`  - ${message}`);
+  console.warn('');
+};
+
 const isHttps = (value) => {
   try {
     return new URL(value).protocol === 'https:';
@@ -92,7 +113,7 @@ function validate(file, data, body) {
 
   const text = (value, field, max, required) => {
     if (value === undefined || value === null || value === '') {
-      if (required) fail(file, `needs a ${field}`);
+      if (required) fail(file, `needs ${field}`);
       return undefined;
     }
     if (typeof value !== 'string') {
@@ -129,7 +150,7 @@ function validate(file, data, body) {
     }
   }
 
-  return {
+  const alert = {
     id: text(id, 'an id', LIMITS.id, true),
     severity,
     title: text(title, 'a title', LIMITS.title, true),
@@ -140,6 +161,17 @@ function validate(file, data, body) {
     endsAt: endsAt === '' || endsAt === undefined ? null : endsAt,
     body
   };
+
+  if (alert.summary && alert.summary.length > SUMMARY_CLAMPED_AT) {
+    note(
+      file,
+      `the summary is ${alert.summary.length} characters and the dashboard's toast shows about ` +
+        `${SUMMARY_CLAMPED_AT}. Lead with the symptom in a sentence that stands on its own, and ` +
+        'leave the workaround to its own field and the long version to the body.'
+    );
+  }
+
+  return alert;
 }
 
 async function readAnnouncements() {
@@ -392,6 +424,7 @@ async function main() {
 
   if (checkOnly) {
     console.log(`${announcements.length} announcement(s) look fine.`);
+    printNotes();
     return;
   }
 
@@ -423,6 +456,7 @@ async function main() {
   console.log(
     `Built ${announcements.length} announcement(s), ${active} active, ${feed.length} in the feed, into dist/`
   );
+  printNotes();
 }
 
 main().catch((error) => {