diff --git a/src/app/api/monitoring/glitchtip/__tests__/route.test.ts b/src/app/api/monitoring/glitchtip/__tests__/route.test.ts
index ca5b1efbc..c1bf70f32 100644
--- a/src/app/api/monitoring/glitchtip/__tests__/route.test.ts
+++ b/src/app/api/monitoring/glitchtip/__tests__/route.test.ts
@@ -6,6 +6,7 @@ vi.mock("@/lib/db", () => ({ prisma: {} }));
 vi.mock("@/lib/api-handler", () => ({
   apiHandler: <T extends (...args: unknown[]) => Promise<Response>>(h: T): T =>
     h,
+  requireAuth: vi.fn(),
 }));
 
 vi.mock("@/lib/rate-limit", () => ({
@@ -29,6 +30,7 @@ import { POST } from "../route";
 import { checkRateLimit } from "@/lib/rate-limit";
 import { getGlitchtipSettings } from "@/lib/monitoring-settings";
 import { sendGlitchtipEvent } from "@/lib/monitoring/glitchtip";
+import { requireAuth } from "@/lib/api-handler";
 
 function jsonReq(body: unknown, contentType = "application/json"): NextRequest {
   return new NextRequest("http://localhost/api/monitoring/glitchtip", {
@@ -40,6 +42,9 @@ function jsonReq(body: unknown, contentType = "application/json"): NextRequest {
 
 beforeEach(() => {
   vi.clearAllMocks();
+  vi.mocked(requireAuth).mockResolvedValue({
+    user: { id: "user-1" },
+  } as Awaited<ReturnType<typeof requireAuth>>);
   vi.mocked(checkRateLimit).mockResolvedValue({
     allowed: true,
     remaining: 19,
@@ -58,6 +63,20 @@ beforeEach(() => {
 });
 
 describe("POST /api/monitoring/glitchtip", () => {
+  it("relays nothing for a caller without a session", async () => {
+    vi.mocked(requireAuth).mockRejectedValue(new Error("Unauthorized"));
+    await expect(POST(jsonReq({ message: "injected" }))).rejects.toThrow();
+    expect(sendGlitchtipEvent).not.toHaveBeenCalled();
+    expect(checkRateLimit).not.toHaveBeenCalled();
+  });
+
+  it("limits the relay per account", async () => {
+    await POST(jsonReq({ message: "boom" }));
+    expect(vi.mocked(checkRateLimit).mock.calls[0]![0]).toBe(
+      "glitchtip:user:user-1",
+    );
+  });
+
   it("returns 429 when rate limit is exceeded", async () => {
     vi.mocked(checkRateLimit).mockResolvedValue({
       allowed: false,
@@ -169,20 +188,9 @@ describe("POST /api/monitoring/glitchtip", () => {
     expect(res.status).toBe(502);
   });
 
-  it("rate-limits per IP — uses x-forwarded-for as the bucket key", async () => {
-    const r = new NextRequest("http://localhost/api/monitoring/glitchtip", {
-      method: "POST",
-      headers: {
-        "content-type": "application/json",
-        "x-forwarded-for": "10.0.0.42",
-      },
-      body: JSON.stringify({ message: "boom" }),
-    });
-    await POST(r);
+  it("keeps the documented 20 per minute window", async () => {
+    await POST(jsonReq({ message: "boom" }));
     const callArgs = vi.mocked(checkRateLimit).mock.calls[0];
-    // First arg is the bucket key — must include the resolved client IP.
-    expect(callArgs?.[0]).toContain("10.0.0.42");
-    // 20 requests / 60 000 ms — guard the documented sliding window.
     expect(callArgs?.[1]).toBe(20);
     expect(callArgs?.[2]).toBe(60_000);
   });
diff --git a/src/app/api/monitoring/glitchtip/route.ts b/src/app/api/monitoring/glitchtip/route.ts
index 0d444cc59..00715f9b8 100644
--- a/src/app/api/monitoring/glitchtip/route.ts
+++ b/src/app/api/monitoring/glitchtip/route.ts
@@ -4,13 +4,12 @@ import {
   apiError,
   apiSuccess,
   apiValidationError,
-  getClientIp,
   sanitiseZodIssues,
 } from "@/lib/api-response";
 import { checkRateLimit } from "@/lib/rate-limit";
 import { getGlitchtipSettings } from "@/lib/monitoring-settings";
 import { sendGlitchtipEvent } from "@/lib/monitoring/glitchtip";
-import { apiHandler } from "@/lib/api-handler";
+import { apiHandler, requireAuth } from "@/lib/api-handler";
 import { annotate, getEvent } from "@/lib/logging/context";
 
 const clientErrorSchema = z
@@ -24,11 +23,17 @@ const clientErrorSchema = z
   })
   .strict();
 
+/**
+ * The browser's error reporter relays here into the operator's GlitchTip.
+ * It needs a signed-in session: the relay used to be anonymous, so anyone
+ * could write events into the incident list, limited only per address. A
+ * page that fails before sign-in goes unreported, which is the price.
+ */
 export const POST = apiHandler(async (request: NextRequest) => {
   annotate({ action: { name: "monitoring.glitchtip.report" } });
 
-  const ip = getClientIp(request);
-  const rl = await checkRateLimit(`glitchtip:${ip}`, 20, 60 * 1000);
+  const { user } = await requireAuth();
+  const rl = await checkRateLimit(`glitchtip:user:${user.id}`, 20, 60 * 1000);
   if (!rl.allowed) return apiError("Rate limit exceeded", 429);
 
   const settings = await getGlitchtipSettings();
diff --git a/src/lib/logging/__tests__/redact.test.ts b/src/lib/logging/__tests__/redact.test.ts
index 2d9d1511c..5912b81bf 100644
--- a/src/lib/logging/__tests__/redact.test.ts
+++ b/src/lib/logging/__tests__/redact.test.ts
@@ -325,3 +325,55 @@ describe("notification quick-answer token in the path", () => {
     );
   });
 });
+
+/**
+ * Prisma prints a failed call, arguments and all, into its error message and
+ * stack. Those went to the logs and to the operator's GlitchTip with a
+ * measurement's value or a note's text inside.
+ */
+describe("redactSecrets — a Prisma call's printed arguments", () => {
+  const message = [
+    "",
+    "Invalid `prisma.measurement.create()` invocation:",
+    "",
+    "{",
+    "  data: {",
+    '    type: "BLOOD_PRESSURE_SYS",',
+    "    value: 187,",
+    '    note: "felt dizzy after the argument",',
+    "+   userId: String",
+    "  }",
+    "}",
+    "",
+    "Argument `userId` is missing.",
+  ].join("\n");
+
+  it("keeps the call and the reason and drops the arguments", () => {
+    const out = redactSecrets(message);
+    expect(out).toContain("Invalid `prisma.measurement.create()` invocation");
+    expect(out).toContain("[query arguments removed]");
+    expect(out).toContain("Argument `userId` is missing.");
+    expect(out).not.toContain("187");
+    expect(out).not.toContain("dizzy");
+  });
+
+  it("keeps the stack frames after the arguments", () => {
+    const stack = `PrismaClientValidationError: ${message}\n    at Mn (/app/.next/server/chunks/1.js:1:2)\n    at async POST (/app/.next/server/app/api/measurements/route.js:3:4)`;
+    const out = redactSecrets(stack);
+    expect(out).not.toContain("dizzy");
+    expect(out).toContain("    at async POST");
+  });
+
+  it("drops a reason line that is not one of the field-naming forms", () => {
+    const out = redactSecrets(
+      'Invalid `prisma.note.update()` invocation in\n/app/x.js:1:1\n\n→ 1 prisma.note.update({ data: { text: "private" } })\n\nprivate text echoed back',
+    );
+    expect(out).not.toContain("private");
+  });
+
+  it("leaves every other message alone", () => {
+    expect(redactSecrets("plain failure at step 3")).toBe(
+      "plain failure at step 3",
+    );
+  });
+});
diff --git a/src/lib/logging/redact.ts b/src/lib/logging/redact.ts
index 84f9ce9df..ee83cd33d 100644
--- a/src/lib/logging/redact.ts
+++ b/src/lib/logging/redact.ts
@@ -91,9 +91,39 @@ function redactPathSegments(input: string): string {
   return out;
 }
 
+/**
+ * A Prisma client error describes its failed call by printing the call: the
+ * code frame around it, or with no source map the arguments object itself,
+ * health values and all. Everything between the "Invalid `prisma.x.y()`
+ * invocation" line and the stack frames goes; the reason line stays when it
+ * is one of the forms that name a field rather than a value.
+ */
+const PRISMA_INVOCATION = /Invalid `[^`\n]*` invocation[^\n]*/;
+const PRISMA_REASON =
+  /^(?:Argument `|Unknown argument `|Unknown field `|Invalid value for argument `|Unique constraint failed|Foreign key constraint|Null constraint violation|An operation failed because|Transaction )/;
+
+export function redactPrismaInvocation(input: string): string {
+  const head = PRISMA_INVOCATION.exec(input);
+  if (!head) return input;
+  const start = head.index + head[0].length;
+  const framesAt = input.indexOf("\n    at ", start);
+  const detail = input.slice(start, framesAt === -1 ? undefined : framesAt);
+  const reason = detail
+    .split("\n")
+    .map((line) => line.trim())
+    .filter(Boolean)
+    .at(-1);
+  return (
+    input.slice(0, start) +
+    "\n[query arguments removed]" +
+    (reason && PRISMA_REASON.test(reason) ? `\n${reason}` : "") +
+    (framesAt === -1 ? "" : input.slice(framesAt))
+  );
+}
+
 export function redactSecrets(input: string): string {
   return (
-    redactPathSegments(input)
+    redactPathSegments(redactPrismaInvocation(input))
       .replace(/Bearer\s+\S+/gi, "Bearer [REDACTED]")
       .replace(/bot\d+:[A-Za-z0-9_-]+/g, "bot[REDACTED]")
       // `sk-` is a common English-prefix substring (task-force, risk-
diff --git a/src/lib/monitoring/glitchtip.ts b/src/lib/monitoring/glitchtip.ts
index 779d45daa..e9a16eb50 100644
--- a/src/lib/monitoring/glitchtip.ts
+++ b/src/lib/monitoring/glitchtip.ts
@@ -1,3 +1,4 @@
+import { redactOptional, redactSecrets } from "@/lib/logging/redact";
 import { safeFetch } from "@/lib/safe-fetch";
 
 interface ParsedGlitchtipDsn {
@@ -245,7 +246,13 @@ export async function sendGlitchtipEvent(params: {
   }
 
   const eventId = createEventId();
-  const payload = buildEventPayload(eventId, params.input);
+  // The egress boundary: whatever a caller passed, the message and stack are
+  // scrubbed of credentials and of a Prisma call's printed arguments here.
+  const payload = buildEventPayload(eventId, {
+    ...params.input,
+    message: redactSecrets(params.input.message),
+    stack: redactOptional(params.input.stack),
+  });
   const envelopeBody = buildEnvelopeBody(config, eventId, payload);
 
   const envelopeResult = await tryEnvelope(config, envelopeBody);