diff --git a/backend/__tests__/unit/config/nativeAgents.scoutLinearCard.test.js b/backend/__tests__/unit/config/nativeAgents.scoutLinearCard.test.js
new file mode 100644
index 0000000000..44213c81fe
--- /dev/null
+++ b/backend/__tests__/unit/config/nativeAgents.scoutLinearCard.test.js
@@ -0,0 +1,39 @@
+/**
+ * Scout posts Linear list results as a kind:'ui' card (TASK-573, D98).
+ *
+ * The prompt is the only thing that tells Scout the card exists, so these tests
+ * pin three things: the catalogue tuple it quotes is the live revision file (not
+ * a copy that can drift), the example source it teaches passes the same
+ * validator a real write goes through, and the rule is present at all.
+ */
+const { scoutApp } = require('../../../config/native-agents/scout');
+const revision = require('../../../config/uiCardCatalogueRevision.json');
+const { validateAgentCardPayload } = require('../../../services/uiCardValidation');
+
+const prompt = scoutApp.systemPrompt;
+
+// The example copied from the prompt, so a changed example fails here too.
+const EXAMPLE_SOURCE = 'root = Card("Linear issues", [Table([Col("Issue"), Col("Status")], '
+  + '[["LIN-12 Fix login", "In progress"]])])';
+
+describe('Scout Linear list results as a card', () => {
+  it('teaches the rule with the live catalogue tuple', () => {
+    expect(prompt).toContain('LINEAR LIST RESULTS');
+    expect(prompt).toContain(`"catalogId":"${revision.catalogId}"`);
+    expect(prompt).toContain(`"catalogRev":${revision.catalogRev}`);
+    expect(prompt).toContain(`"catalogHash":"${revision.catalogHash}"`);
+  });
+
+  it('teaches an example the card validator accepts', () => {
+    expect(prompt).toContain(EXAMPLE_SOURCE);
+    const payload = {
+      ...revision, kind: 'ui', v: 1, lang: 'openui@1', source: EXAMPLE_SOURCE, 
+    };
+    expect(() => validateAgentCardPayload('card', payload, 'LIN-12 Fix login (In progress)')).not.toThrow();
+  });
+
+  it('names the card as the path for list results, with a text fallback', () => {
+    expect(prompt).toContain('messageType "card"');
+    expect(prompt).toContain('fallback every reader sees');
+  });
+});
diff --git a/backend/config/native-agents/scout.ts b/backend/config/native-agents/scout.ts
index 3b63a15c02..afe953b422 100644
--- a/backend/config/native-agents/scout.ts
+++ b/backend/config/native-agents/scout.ts
@@ -1,5 +1,6 @@
 import type { NativeAgentDefinition } from './types';
 import { composePrompt } from './housePreamble';
+import UI_CARD_REVISION from '../uiCardCatalogueRevision.json';
 
 /**
  * Scout — the per-user onboarding admin agent (retention plan D4; named
@@ -294,7 +295,20 @@ export const scoutApp = {
     + '- They want Commonly to run an agent for them, or would rather not '
     + 'install anything → commonly_offer_hosted_agent.\n'
     + '- commonly_read_context before answering questions about what happened '
-    + 'here.',
+    + 'here.\n'
+    + '\n'
+    + 'LINEAR LIST RESULTS: when a linear.* list tool (for example linear.list_issues) '
+    + 'returns issues, answer with one card, not bullet prose. Call commonly_post_message '
+    + 'with messageType "card". Its content is a short plain-text list of the same '
+    + 'issues, which is the fallback every reader sees. Its payload is '
+    + `{"kind":"ui","v":1,"lang":"openui@1","catalogId":"${UI_CARD_REVISION.catalogId}",`
+    + `"catalogRev":${UI_CARD_REVISION.catalogRev},"catalogHash":"${UI_CARD_REVISION.catalogHash}",`
+    + '"source":"<OpenUI source>"}. The source uses only the catalogue components '
+    + 'Card, Table, Col and Text, in one statement set, for example: '
+    + 'root = Card("Linear issues", [Table([Col("Issue"), Col("Status")], '
+    + '[["LIN-12 Fix login", "In progress"]])]). Every row needs one cell per Col. '
+    + 'Show at most 10 rows and say how many more there are in a Text line. Keep each '
+    + 'cell under 80 characters. Copy the catalogue fields exactly.',
     'Never claim the user\'s own agent is connected or working — the '
     + 'connect page verifies that, not you. Point them there instead. And '
     + 'remember you are the product\'s first impression: an invented product '