feat(coach): collapsible evidence-block disclosure under assistant bubbles

Render the v1.4.22 keyValues array as a click-to-expand "Worauf
bezieht sich das?" / "What I'm looking at" disclosure under each
assistant message. Closed by default; rows show label, value, unit,
and window with Dracula muted-foreground accents and a chevron that
rotates on open. Source chips stay above the disclosure so users see
both abstraction layers, and the whole block hides when keyValues is
empty.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

messages/de.json

@@ -871,6 +871,7 @@
       "sourcesFresh": "Aktuell",
       "sourcesStale": "Veraltet",
       "sourcesFooter": "Der Coach liest nur Daten, die du verbunden hast.",
+      "evidenceLabel": "Worauf bezieht sich das?",
       "metric": {
         "bp": "Blutdruck",
         "weight": "Gewicht",

messages/en.json

@@ -871,6 +871,7 @@
       "sourcesFresh": "Fresh",
       "sourcesStale": "Stale",
       "sourcesFooter": "The Coach reads only the data you've connected.",
+      "evidenceLabel": "What I'm looking at",
       "metric": {
         "bp": "Blood pressure",
         "weight": "Weight",

src/components/insights/coach-panel/__tests__/message-thread.test.tsx

@@ -216,4 +216,107 @@ describe("<MessageThread>", () => {
       "Frag mich etwas zu deinen Trends, Medikamenten oder Messwerten",
     );
   });
+
+  it("renders the evidence-block disclosure when keyValues is non-empty (EN)", () => {
+    // v1.4.22 — the Coach surfaces load-bearing numbers in a
+    // collapsible "What I'm looking at" disclosure under the assistant
+    // bubble. Verify the structure renders correctly and the entries
+    // show label / value / unit / window.
+    const withKeyValues: CoachConversationDetailDTO = {
+      ...baseConversation,
+      messages: [
+        baseConversation.messages[0],
+        {
+          ...baseConversation.messages[1],
+          metricSource: {
+            windows: ["last30days"],
+            metrics: ["bp"],
+            keyValues: [
+              {
+                label: "avg7 systolic",
+                value: "138",
+                unit: "mmHg",
+                window: "last7days",
+              },
+              {
+                label: "avg30 systolic",
+                value: "134",
+                unit: "mmHg",
+                window: "last30days",
+              },
+            ],
+          },
+        },
+      ],
+    };
+    const html = render(<MessageThread conversation={withKeyValues} />);
+    expect(html).toContain('data-slot="coach-evidence"');
+    expect(html).toContain("What I&#x27;m looking at");
+    expect(html).toContain('data-slot="coach-evidence-list"');
+    const rows = (html.match(/data-slot="coach-evidence-row"/g) ?? []).length;
+    expect(rows).toBe(2);
+    expect(html).toContain("avg7 systolic");
+    expect(html).toContain("138 mmHg");
+    expect(html).toContain("(last7days)");
+    expect(html).toContain("avg30 systolic");
+    expect(html).toContain("134 mmHg");
+    // Disclosure is collapsed by default (no `open` attribute).
+    expect(html).not.toMatch(/<details[^>]*\bopen\b/);
+  });
+
+  it("renders the evidence-block label in German under 'de' locale", () => {
+    const withKeyValues: CoachConversationDetailDTO = {
+      ...baseConversation,
+      messages: [
+        baseConversation.messages[0],
+        {
+          ...baseConversation.messages[1],
+          metricSource: {
+            windows: ["last30days"],
+            metrics: ["bp"],
+            keyValues: [
+              {
+                label: "avg30 systolisch",
+                value: "138",
+                unit: "mmHg",
+                window: "last30days",
+              },
+            ],
+          },
+        },
+      ],
+    };
+    const html = render(<MessageThread conversation={withKeyValues} />, "de");
+    expect(html).toContain("Worauf bezieht sich das?");
+  });
+
+  it("renders entries without unit or window cleanly", () => {
+    const withKeyValues: CoachConversationDetailDTO = {
+      ...baseConversation,
+      messages: [
+        baseConversation.messages[0],
+        {
+          ...baseConversation.messages[1],
+          metricSource: {
+            windows: [],
+            metrics: ["compliance"],
+            keyValues: [{ label: "30-day adherence", value: "96" }],
+          },
+        },
+      ],
+    };
+    const html = render(<MessageThread conversation={withKeyValues} />);
+    expect(html).toContain("30-day adherence");
+    // No stray empty unit/window markup.
+    expect(html).not.toMatch(/30-day adherence:\s*<\/span>\s*<strong[^>]*>\s*</);
+  });
+
+  it("hides the disclosure entirely when keyValues is empty or absent", () => {
+    // baseConversation.messages[1].metricSource has no `keyValues`
+    // field — the source chips still render but the disclosure does
+    // not appear at all.
+    const html = render(<MessageThread conversation={baseConversation} />);
+    expect(html).not.toContain('data-slot="coach-evidence"');
+    expect(html).not.toContain("What I&#x27;m looking at");
+  });
 });

src/components/insights/coach-panel/message-thread.tsx

@@ -1,7 +1,7 @@
 "use client";
 
 import { useEffect, useRef } from "react";
-import { Bot, Sparkles, User } from "lucide-react";
+import { Bot, ChevronRight, Sparkles, User } from "lucide-react";
 
 import { cn } from "@/lib/utils";
 import { useTranslations } from "@/lib/i18n/context";
@@ -202,6 +202,8 @@ function ChatBubble({
         ? t("insights.coach.errorProvider")
         : null;
 
+  const keyValues = metricSource?.keyValues ?? [];
+
   return (
     <div
       data-slot="coach-bubble-assistant"
@@ -232,6 +234,55 @@ function ChatBubble({
           <p className="text-dracula-orange/90 text-xs">{safeError}</p>
         )}
         {metricSource && <SourceChips provenance={metricSource} />}
+        {keyValues.length > 0 && (
+          <details
+            data-slot="coach-evidence"
+            className={cn(
+              "border-border/50 bg-muted/30 group rounded-md border",
+              "px-2.5 py-1.5 text-xs",
+            )}
+          >
+            <summary
+              data-slot="coach-evidence-summary"
+              className={cn(
+                "text-muted-foreground hover:text-foreground flex cursor-pointer",
+                "items-center gap-1.5 leading-relaxed",
+                "[&::-webkit-details-marker]:hidden marker:hidden",
+                "focus-visible:ring-ring/50 rounded outline-none focus-visible:ring-2",
+              )}
+            >
+              <ChevronRight
+                aria-hidden="true"
+                className="size-3 transition-transform group-open:rotate-90"
+              />
+              <span>{t("insights.coach.evidenceLabel")}</span>
+            </summary>
+            <ul
+              data-slot="coach-evidence-list"
+              className="text-foreground mt-2 flex flex-col gap-1"
+            >
+              {keyValues.map((kv, idx) => (
+                <li
+                  key={`${kv.label}-${idx}`}
+                  data-slot="coach-evidence-row"
+                  className="leading-relaxed"
+                >
+                  <span className="text-muted-foreground">{kv.label}:</span>{" "}
+                  <strong className="font-semibold">
+                    {kv.value}
+                    {kv.unit ? ` ${kv.unit}` : ""}
+                  </strong>
+                  {kv.window && (
+                    <span className="text-muted-foreground">
+                      {" "}
+                      ({kv.window})
+                    </span>
+                  )}
+                </li>
+              ))}
+            </ul>
+          </details>
+        )}
       </div>
     </div>
   );