diff --git a/.server-changes/report-messages-not-treeshaken.md b/.server-changes/report-messages-not-treeshaken.md
new file mode 100644
index 00000000000..b599e84f1ce
--- /dev/null
+++ b/.server-changes/report-messages-not-treeshaken.md
@@ -0,0 +1,6 @@
+---
+area: webapp
+type: fix
+---
+
+Fix the health report failing with an internal error when requested through the API.
diff --git a/apps/webapp/app/presenters/v3/reports/health/health-messages.ts b/apps/webapp/app/presenters/v3/reports/health/health-messages.ts
index 888b2b54b73..2475118a685 100644
--- a/apps/webapp/app/presenters/v3/reports/health/health-messages.ts
+++ b/apps/webapp/app/presenters/v3/reports/health/health-messages.ts
@@ -8,7 +8,7 @@
  * metrics / evidence — meaning lives here, numbers stay facts.
  */
 
-import { registerReportMessages, type ReportMessages } from "../report-messages";
+import { type ReportMessages } from "../report-messages";
 import { type ReasonCode, type Severity } from "../report-view-model";
 
 /** Metric id -> expanded display label. */
@@ -166,5 +166,3 @@ export const healthMessages: ReportMessages = {
   statementMessage,
   actionMessage: (code) => ACTIONS[code] ?? code,
 };
-
-registerReportMessages("health", healthMessages);
diff --git a/apps/webapp/app/presenters/v3/reports/health/health.ts b/apps/webapp/app/presenters/v3/reports/health/health.ts
index 08beae3894c..fa56e7b630e 100644
--- a/apps/webapp/app/presenters/v3/reports/health/health.ts
+++ b/apps/webapp/app/presenters/v3/reports/health/health.ts
@@ -26,7 +26,6 @@ import { applyFlowPolicy, buildFlowRead, interpretFlow } from "./flow";
 import { interpretLiveness } from "./liveness";
 // Registers the "health" message catalog (side effect) so the renderer resolves this report's
 // codes. Kept here — the health report's entry module — so loading it always registers its prose.
-import "./health-messages";
 
 // Re-exported so the data layer + tests keep a single import path (`./health`).
 export { HEALTH_THRESHOLDS, isPendingIncreasing, type HealthInput } from "./health-core";
diff --git a/apps/webapp/app/presenters/v3/reports/report-message-catalogs.ts b/apps/webapp/app/presenters/v3/reports/report-message-catalogs.ts
new file mode 100644
index 00000000000..eca36e7e95a
--- /dev/null
+++ b/apps/webapp/app/presenters/v3/reports/report-message-catalogs.ts
@@ -0,0 +1,11 @@
+/**
+ * Catalogs by value, in a module that imports ONLY the per-report `*-messages`
+ * files — no loaders, no IO. Presentation stays decoupled from the data layer,
+ * and a value import can't be tree-shaken away.
+ */
+import { healthMessages } from "./health/health-messages";
+import { type ReportMessages } from "./report-messages";
+
+export const REPORT_MESSAGE_CATALOGS: Record<string, ReportMessages> = {
+  health: healthMessages,
+};
diff --git a/apps/webapp/app/presenters/v3/reports/report-messages.ts b/apps/webapp/app/presenters/v3/reports/report-messages.ts
index 2d90ea016ed..1c549f78a1c 100644
--- a/apps/webapp/app/presenters/v3/reports/report-messages.ts
+++ b/apps/webapp/app/presenters/v3/reports/report-messages.ts
@@ -5,6 +5,7 @@
  * No report vocabulary here — that would re-couple the renderer to a specific report.
  */
 
+import { REPORT_MESSAGE_CATALOGS } from "./report-message-catalogs";
 import { type ReasonCode, type Severity } from "./report-view-model";
 
 /**
@@ -22,16 +23,11 @@ export type ReportMessages = {
   actionMessage(code: ReasonCode): string;
 };
 
-const catalogs = new Map<string, ReportMessages>();
-
-/** Register a report's catalog under its title (e.g. "health"). Called for its side effect. */
-export function registerReportMessages(title: string, messages: ReportMessages): void {
-  catalogs.set(title, messages);
-}
-
-/** Look up a report's catalog by `vm.title`. Throws if the report never registered one. */
+/** Look up a report's catalog by `vm.title`. Catalogs are values, never
+ * registered at import time — side-effect registration is what the production
+ * bundle tree-shakes away. */
 export function reportMessages(title: string): ReportMessages {
-  const messages = catalogs.get(title);
+  const messages = REPORT_MESSAGE_CATALOGS[title];
   if (!messages) {
     throw new Error(`report-messages: no catalog registered for report "${title}"`);
   }