diff --git a/workers/iroh-v2/src/dashboard-control.ts b/workers/iroh-v2/src/dashboard-control.ts
index 77cf7d16725f..d607135f4af9 100644
--- a/workers/iroh-v2/src/dashboard-control.ts
+++ b/workers/iroh-v2/src/dashboard-control.ts
@@ -7,7 +7,7 @@ import { canonicalJSON, hash } from "./crypto";
 import { DASHBOARD_AUTHORITY_HEADER, DashboardClaimsSchema, type DashboardClaims } from "./dashboard-auth";
 import { acknowledgeDelivery, DeliveryStateSchema, deliveryUsage, emptyDeliveryState, prepareDelivery } from "./delivery";
 import type { Environment } from "./environment";
-import { OperationError } from "./errors";
+import { failureDiagnostics, OperationError } from "./errors";
 import { observe } from "./observability";
 import { unwrap, type UserUsage } from "./user-usage-object";
 
@@ -66,7 +66,7 @@ export class DashboardControl {
       } finally { this.services.opening.delete(sessionId); }
     } catch (error) {
       const failure = errorResponse(error, requestId).failure;
-      observe(this.ctx, this.env, { event: "iroh.dashboard.failure", requestId, code: failure.code, status: failure.status });
+      observe(this.ctx, this.env, { event: "iroh.dashboard.failure", requestId, code: failure.code, status: failure.status, ...failureDiagnostics(error) });
       return httpFailure(error, requestId);
     }
   }
diff --git a/workers/iroh-v2/src/dashboard-routing.ts b/workers/iroh-v2/src/dashboard-routing.ts
index 11631563e480..1ff19aaac906 100644
--- a/workers/iroh-v2/src/dashboard-routing.ts
+++ b/workers/iroh-v2/src/dashboard-routing.ts
@@ -2,7 +2,7 @@ import type { StackAuthority } from "./auth";
 import { encodeResponse, errorResponse, httpFailure, inputRequestId, parseInput, readBoundedBody } from "./boundary";
 import { DashboardOpenSchema } from "./contracts/common";
 import { DASHBOARD_AUTHORITY_HEADER, issueDashboardTicket, verifyDashboardTicket } from "./dashboard-auth";
-import { OperationError } from "./errors";
+import { failureDiagnostics, OperationError } from "./errors";
 
 interface Dependencies {
   environment: string; projectId: string; keys: Readonly<Record<string, string>>;
@@ -69,7 +69,7 @@ export async function routeDashboard(request: Request, services: Dependencies):
     return cors(await services.dispatchTeam(claims.authority.teamId, forwarded));
   } catch (error) {
     const failure = errorResponse(error, requestId).failure;
-    services.observe?.({ event: "iroh.dashboard.failure", requestId, code: failure.code, status: failure.status });
+    services.observe?.({ event: "iroh.dashboard.failure", requestId, code: failure.code, status: failure.status, ...failureDiagnostics(error) });
     return cors(httpFailure(error, requestId));
   }
 }
diff --git a/workers/iroh-v2/src/errors.ts b/workers/iroh-v2/src/errors.ts
index 6b654cce754a..83ee4e15ae05 100644
--- a/workers/iroh-v2/src/errors.ts
+++ b/workers/iroh-v2/src/errors.ts
@@ -20,16 +20,39 @@ export function publicError(error: unknown): OperationError {
  * records only error names and known capacity markers from the cause chain.
  */
 export function errorSummary(error: unknown): string {
-  const markers = ["socket_output_capacity", "socket_capacity"] as const;
   const parts: string[] = [];
   let current: unknown = error;
   for (let depth = 0; current !== undefined && current !== null && depth < 4; depth += 1) {
     const rawName = current instanceof Error ? current.name : typeof current;
-    const name = ["Error", "TypeError", "RangeError", "SyntaxError", "DrizzleError", "DrizzleQueryError"].includes(rawName) ? rawName : "Error";
+    const name = ["Error", "TypeError", "RangeError", "SyntaxError", "DrizzleError", "DrizzleQueryError", "ZodError"].includes(rawName) ? rawName : "Error";
     const text = current instanceof Error ? current.message : String(current);
-    const marker = markers.find(candidate => text.includes(candidate));
-    parts.push(marker ? `${name}:${marker}` : name);
+    const marker = FAILURE_MARKERS.find(([needle]) => text.includes(needle))?.[1];
+    // Workers runtime errors carry these booleans; they name the platform
+    // failure class without exposing the message text.
+    const flags = ["retryable", "overloaded", "remote"].filter(flag => current !== null && typeof current === "object" && Reflect.get(current, flag) === true);
+    parts.push([marker ? `${name}:${marker}` : name, ...flags].join("+"));
     current = current instanceof Error ? current.cause : undefined;
   }
-  return parts.join(" <- ").slice(0, 160);
+  return parts.join(" <- ").slice(0, 200);
+}
+
+/**
+ * Known failure texts mapped to fixed tags. Storage guards raise the first
+ * group; the rest are Workers and Durable Object runtime failures. Only the
+ * tag is recorded, never the matched message.
+ */
+const FAILURE_MARKERS: readonly (readonly [string, string])[] = [
+  ["socket_output_capacity", "socket_output_capacity"], ["socket_capacity", "socket_capacity"],
+  ["audit_limit", "audit_limit"], ["device_limit", "device_limit"], ["storage_limit", "storage_limit"],
+  ["SQLITE_BUSY", "sqlite_busy"], ["SQLITE_FULL", "sqlite_full"], ["CONSTRAINT", "sqlite_constraint"],
+  ["code was updated", "do_code_updated"], ["Durable Object reset", "do_reset"],
+  ["Network connection lost", "network_lost"], ["overloaded", "overloaded"],
+  ["exceeded timeout", "storage_timeout"], ["memory limit", "memory_limit"], ["CPU time", "cpu_limit"],
+  ["transient issue", "do_transient"], ["too many subrequests", "subrequest_limit"],
+  ["The operation was aborted", "aborted"], ["timed out", "timed_out"], ["fetch failed", "fetch_failed"],
+];
+
+/** Telemetry fields for a failure: a cause only when the error was not classified. */
+export function failureDiagnostics(error: unknown): { cause?: string } {
+  return error instanceof OperationError ? {} : { cause: errorSummary(error) };
 }
diff --git a/workers/iroh-v2/src/index.ts b/workers/iroh-v2/src/index.ts
index 997b89e8e913..6eb80ee36b07 100644
--- a/workers/iroh-v2/src/index.ts
+++ b/workers/iroh-v2/src/index.ts
@@ -1,4 +1,5 @@
 import { errorResponse, httpFailure } from "./boundary";
+import { failureDiagnostics } from "./errors";
 import { runtime, type Environment } from "./environment";
 import { routeControl, objectName } from "./routing";
 import { unwrap } from "./user-usage-object";
@@ -30,7 +31,7 @@ export default {
       });
     } catch (error) {
       const failure = errorResponse(error, "unidentified").failure;
-      observe(ctx, env, { event: "iroh.http.failure", environment: env.ENVIRONMENT, path: new URL(request.url).pathname, code: failure.code, status: failure.status, retryable: failure.retryable });
+      observe(ctx, env, { event: "iroh.http.failure", environment: env.ENVIRONMENT, path: new URL(request.url).pathname, code: failure.code, status: failure.status, retryable: failure.retryable, ...failureDiagnostics(error) });
       response = httpFailure(error);
     }
     observe(ctx, env, { event: "iroh.http.response", environment: env.ENVIRONMENT, path: new URL(request.url).pathname, status: response.status, durationMs: Date.now() - started });
diff --git a/workers/iroh-v2/src/routing.ts b/workers/iroh-v2/src/routing.ts
index 3272ba5bafe2..0bff72c56553 100644
--- a/workers/iroh-v2/src/routing.ts
+++ b/workers/iroh-v2/src/routing.ts
@@ -1,13 +1,13 @@
 import { z } from "zod";
 import type { StackAuthority, VerifiedAuthority } from "./auth";
-import { decodeJSON, errorResponse, httpFailure, inputRequestId, parseInput, parseSocketSetup, readBoundedBody, INPUT_BYTES } from "./boundary";
+import { decodeJSON, errorResponse, httpFailure, inputOperation, inputRequestId, parseInput, parseSocketSetup, readBoundedBody, INPUT_BYTES } from "./boundary";
 import { identifier, timestamp } from "./contracts/common";
 import { SocketSetupSchema, type SocketSetup } from "./contracts/requests";
 import { STORAGE_SCHEMA_VERSION, STORAGE_WRITE_SCHEMA_VERSION } from "./storage/migrations";
 import { HealthSchema } from "./health";
 import { CONTROL_PLANE_RULES, sourceRevision } from "./rules";
 import { API_TICKET_SECONDS, canonicalJSON, decodeBase64URL, encodeBase64URL, verifyTicket } from "./crypto";
-import { OperationError } from "./errors";
+import { failureDiagnostics, OperationError } from "./errors";
 
 export const SETUP_HEADER = "x-cmux-v2-setup";
 const INTERNAL_HEADER = "x-cmux-v2-verified-authority";
@@ -41,6 +41,9 @@ const aliases: Readonly<Record<string, string>> = {
 /** Public requests never control the private headers passed through the DO binding. */
 export async function routeControl(request: Request, dependencies: RoutingDependencies): Promise<Response> {
   let requestId = "unidentified";
+  // Where a failure happened, for telemetry only: route kind, the stage
+  // reached and the requested operation, never request contents.
+  let route = "unknown", stage = "parse", operationName = "none";
   try {
     const url = new URL(request.url);
     const socket = url.pathname === "/v2/control/socket";
@@ -48,6 +51,7 @@ export async function routeControl(request: Request, dependencies: RoutingDepend
     const operation = url.pathname === "/v2/requests" || Object.hasOwn(aliases, url.pathname);
     const health = url.pathname === "/v2/health";
     if ((!socket && !session && !operation && !health) || url.search) throw new OperationError("unsupported_method", 404);
+    route = socket ? "socket" : session ? "session" : operation ? "request" : health ? "health" : "unknown";
     if (health) return healthResponse(request, dependencies);
     if (request.method !== (socket ? "GET" : "POST")) throw new OperationError("unsupported_method", 405);
     if (socket && request.headers.get("upgrade")?.toLowerCase() !== "websocket") throw new OperationError("invalid_request", 400);
@@ -65,7 +69,10 @@ export async function routeControl(request: Request, dependencies: RoutingDepend
         throw new OperationError("invalid_request", 400);
       }
     }
+    if (operation) operationName = inputOperation(input);
+    stage = "authenticate";
     const authorization = await authenticate(request.headers.get("authorization"), setup, dependencies);
+    stage = "charge";
     if (!operation) await dependencies.chargeOpen(authorization.authority.userId);
     // A fresh Request deliberately copies no caller headers, cookies or credentials.
     const headers = new Headers({
@@ -79,10 +86,12 @@ export async function routeControl(request: Request, dependencies: RoutingDepend
       method: socket ? "GET" : "POST", headers,
       ...(socket ? {} : { body: JSON.stringify({ setup, ...(operation ? { input } : {}) }) }),
     });
+    stage = "dispatch";
     return await dependencies.dispatchTeam(setup.device.identity.teamId, forwarded);
   } catch (error) {
     const failure = errorResponse(error, requestId).failure;
-    dependencies.observe?.({ event: "iroh.control.failure", requestId, code: failure.code, status: failure.status, retryable: failure.retryable });
+    dependencies.observe?.({ event: "iroh.control.failure", requestId, code: failure.code, status: failure.status, retryable: failure.retryable,
+      route, stage, operation: operationName, ...failureDiagnostics(error) });
     return httpFailure(error, requestId);
   }
 }
diff --git a/workers/iroh-v2/src/team-control.ts b/workers/iroh-v2/src/team-control.ts
index 15a439bc95e8..72265960e067 100644
--- a/workers/iroh-v2/src/team-control.ts
+++ b/workers/iroh-v2/src/team-control.ts
@@ -7,7 +7,7 @@ import type { ControlResponse } from "./contracts/responses";
 import { identityKey, issueTicket } from "./crypto";
 import { acknowledgeDelivery, DeliveryStateSchema, deliveryUsage, emptyDeliveryState, prepareDelivery } from "./delivery";
 import { environmentScope, runtime, type Environment } from "./environment";
-import { errorSummary, OperationError, publicError } from "./errors";
+import { failureDiagnostics, OperationError, publicError } from "./errors";
 import { AuthoritySchema, objectName, readInternalRequest } from "./routing";
 import { applyStorageMigrations } from "./storage/migrations";
 import { TeamStore } from "./storage/team-store";
@@ -50,9 +50,13 @@ export class TeamControl extends DurableObject<Environment> {
   async fetch(request: Request): Promise<Response> {
     if (new URL(request.url).pathname === "/dashboard/socket") return this.dashboard.fetch(request);
     let requestId = "unidentified";
+    const pathname = new URL(request.url).pathname;
+    const route = ["/request", "/session", "/socket"].includes(pathname) ? pathname.slice(1) : "unknown";
+    let stage = "parse";
     try {
       const incoming = await readInternalRequest(request);
       requestId = incoming.setup.requestId;
+      stage = incoming.path === "/request" ? "execute" : "open";
       const broker = this.broker(incoming.authority.teamId);
       if (incoming.path === "/request") {
         const session = await broker.authorizeHTTP(incoming.setup, incoming.input, incoming.authority, incoming.expiresAt, incoming.issueTicket);
@@ -66,6 +70,7 @@ export class TeamControl extends DurableObject<Environment> {
       this.scheduleChanges(result, incoming.authority.teamId);
       observe(this.ctx, this.env, { event: "iroh.team.operation", environment: this.env.ENVIRONMENT, operation: result.response.schemaId, requestId, status: 200 });
       if (incoming.path === "/session") return this.json(result.response);
+      stage = "accept";
       if (request.headers.get("upgrade")?.toLowerCase() !== "websocket") throw new OperationError("invalid_request", 400);
       if (this.ctx.getWebSockets().length >= TEAM_SOCKET_LIMIT) throw new OperationError("rate_limited", 429, true, 5000);
       const session = result.session;
@@ -77,15 +82,18 @@ export class TeamControl extends DurableObject<Environment> {
         const client = pair[0], server = pair[1];
         this.ctx.acceptWebSocket(server, ["user:" + session.identity.userId, "device:" + deviceKey]);
         this.save(server, { version: 1, session, deviceKey, delivery: emptyDeliveryState(), outputRevision: 0, closed: false });
+        stage = "send";
         try { await this.enqueue(server, 0, () => this.send(server, result.response)); }
         catch (error) { this.close(server, "slow_consumer"); throw error; }
+        stage = "ready";
         // The replacement is accepted and ready before any previous socket closes.
         for (const old of this.ctx.getWebSockets("device:" + deviceKey)) if (old !== server) this.close(old, "session_replaced");
         return new Response(null, { status: 101, webSocket: client });
       } finally { this.opening.delete(session.sessionId); }
     } catch (error) {
       const failure = publicError(error);
-      observe(this.ctx, this.env, { event: "iroh.team.failure", environment: this.env.ENVIRONMENT, requestId, code: failure.code, status: failure.status, retryable: failure.retryable });
+      observe(this.ctx, this.env, { event: "iroh.team.failure", environment: this.env.ENVIRONMENT, requestId, code: failure.code, status: failure.status, retryable: failure.retryable,
+        route, stage, ...failureDiagnostics(error) });
       return httpFailure(error, requestId);
     }
   }
@@ -126,7 +134,7 @@ export class TeamControl extends DurableObject<Environment> {
         } catch (error) {
           const failure = errorResponse(error, inputRequestId(input));
           status = failure.failure.status; code = failure.failure.code;
-          if (!(error instanceof OperationError)) cause = errorSummary(error);
+          cause = failureDiagnostics(error).cause;
           try { await this.send(ws, failure.body); } catch { this.close(ws, "slow_consumer"); }
           if (["device_revoked", "team_access_revoked", "identity_mismatch", "key_replacement_required"].includes(code)) this.close(ws, code);
         } finally {
diff --git a/workers/iroh-v2/src/user-usage-object.ts b/workers/iroh-v2/src/user-usage-object.ts
index e6bb85a40e1c..5a6c1c0f9e3d 100644
--- a/workers/iroh-v2/src/user-usage-object.ts
+++ b/workers/iroh-v2/src/user-usage-object.ts
@@ -1,7 +1,8 @@
 import { DurableObject } from "cloudflare:workers";
 import { identifier } from "./contracts/common";
 import { environmentScope, type Environment } from "./environment";
-import { errorSummary, OperationError, publicError } from "./errors";
+import { failureDiagnostics, OperationError, publicError } from "./errors";
+import { observe } from "./observability";
 import { objectName } from "./routing";
 import { applyStorageMigrations } from "./storage/migrations";
 import { UserSocketStore } from "./storage/socket-store";
@@ -9,11 +10,13 @@ import { UserUsageStore, type UsageOperation } from "./storage/user-usage";
 import type { ErrorCode } from "./contracts/responses";
 
 type Result<T> = { ok: true; value: T } | { ok: false; code: ErrorCode; status: number; retryable: boolean; retryAfterMs?: number };
-function result<T>(action: () => T): Result<T> {
+function result<T>(action: () => T, report?: (cause: string) => void): Result<T> {
   try { return { ok: true, value: action() }; }
   catch (error) {
     const failure = publicError(error);
-    if (!(error instanceof OperationError)) console.error(JSON.stringify({ event: "iroh.user_usage.unclassified", cause: errorSummary(error) }));
+    // The caller only receives the public code across RPC; report the cause here.
+    const { cause } = failureDiagnostics(error);
+    if (cause) report?.(cause);
     return { ok: false, code: failure.code, status: failure.status, retryable: failure.retryable,
       ...(failure.retryAfterMs === undefined ? {} : { retryAfterMs: failure.retryAfterMs }) };
   }
@@ -36,19 +39,22 @@ export class UserUsage extends DurableObject<Environment> {
   }
 
   consume(userId: string, operation: UsageOperation) {
-    return result(() => { this.assertUser(userId); return this.usage.consume(userId, operation); });
+    return result(() => { this.assertUser(userId); return this.usage.consume(userId, operation); }, this.report("consume"));
   }
   reserveSocket(input: { userId: string; teamId: string; sessionId: string; deviceKey: string }) {
-    return result(() => { this.assertUser(input.userId); this.sockets.reserveSocket(input); });
+    return result(() => { this.assertUser(input.userId); this.sockets.reserveSocket(input); }, this.report("reserveSocket"));
   }
   setOutput(userId: string, sessionId: string, revision: number, bytes: number, messages: number) {
-    return result(() => { this.assertUser(userId); this.sockets.setOutput(userId, sessionId, revision, bytes, messages); });
+    return result(() => { this.assertUser(userId); this.sockets.setOutput(userId, sessionId, revision, bytes, messages); }, this.report("setOutput"));
   }
   releaseSocket(userId: string, sessionId: string) {
-    return result(() => { this.assertUser(userId); this.sockets.releaseSocket(userId, sessionId); });
+    return result(() => { this.assertUser(userId); this.sockets.releaseSocket(userId, sessionId); }, this.report("releaseSocket"));
   }
   listSocketReservations(userId: string) {
-    return result(() => { this.assertUser(userId); return this.sockets.listSocketReservations(userId); });
+    return result(() => { this.assertUser(userId); return this.sockets.listSocketReservations(userId); }, this.report("listSocketReservations"));
+  }
+  private report(operation: string): (cause: string) => void {
+    return cause => observe(this.ctx, this.env, { event: "iroh.user_usage.unclassified", status: 500, environment: this.env.ENVIRONMENT, operation, cause });
   }
   private assertUser(userId: string): void {
     identifier.parse(userId);
diff --git a/workers/iroh-v2/test/errors.test.ts b/workers/iroh-v2/test/errors.test.ts
index 5b9901eb2013..4ef5f6b9d44c 100644
--- a/workers/iroh-v2/test/errors.test.ts
+++ b/workers/iroh-v2/test/errors.test.ts
@@ -1,5 +1,5 @@
 import { expect, test } from "bun:test";
-import { errorSummary } from "../src/errors";
+import { errorSummary, failureDiagnostics, OperationError } from "../src/errors";
 
 test("error summaries keep safe cause categories without SQL or bound parameters", () => {
   const error = new Error(
@@ -17,3 +17,14 @@ test("diagnostics never include a custom error name or message", () => {
   error.name = "credential-value";
   expect(errorSummary(error)).toBe("Error");
 });
+
+test("runtime failures map to fixed tags and platform flags", () => {
+  const overloaded = Object.assign(new Error("Durable Object is overloaded. Requests queued for too long."), { retryable: true, overloaded: true });
+  expect(errorSummary(overloaded)).toBe("Error:overloaded+retryable+overloaded");
+  expect(errorSummary(new TypeError("Network connection lost."))).toBe("TypeError:network_lost");
+});
+
+test("classified operation errors carry no cause", () => {
+  expect(failureDiagnostics(new OperationError("ticket_expired", 401, true))).toEqual({});
+  expect(failureDiagnostics(new Error("x"))).toEqual({ cause: "Error" });
+});
diff --git a/workers/iroh-v2/test/routing.test.ts b/workers/iroh-v2/test/routing.test.ts
index 012aa829401a..1553c2113cf6 100644
--- a/workers/iroh-v2/test/routing.test.ts
+++ b/workers/iroh-v2/test/routing.test.ts
@@ -94,3 +94,26 @@ test("cross-environment setup never reaches Stack or a team object", async () =>
   expect(result.status).toBe(403);
   expect(calls).toEqual({ stack: 0, open: 0, team: 0 });
 });
+
+test("control failures record the route, stage, operation and an unclassified cause", async () => {
+  const { dependencies } = fixture();
+  const events: Record<string, unknown>[] = [];
+  const ticket = await issueTicket(device, "test", key, 99);
+  const reset = Object.assign(new Error("Durable Object reset because its code was updated."), { retryable: true });
+  const result = await routeControl(new Request("https://api.example/v2/requests", {
+    method: "POST", headers: { "content-type": "application/json", authorization: "IrohTicket " + ticket.token, [SETUP_HEADER]: encodedSetup },
+    body: JSON.stringify({ schemaId: "directory.request.v1", requestId: "request" }),
+  }), { ...dependencies, observe: event => events.push(event), dispatchTeam: async () => { throw reset; } });
+  expect(result.status).toBe(500);
+  expect(events).toEqual([expect.objectContaining({
+    event: "iroh.control.failure", code: "internal_error", route: "request", stage: "dispatch",
+    operation: "directory.request", cause: "Error:do_code_updated+retryable",
+  })]);
+  expect(JSON.stringify(events)).not.toContain("code was updated");
+
+  events.length = 0;
+  await routeControl(new Request("https://api.example/v2/control/session", {
+    method: "POST", headers: { "content-type": "application/json", authorization: "Bearer stack-token" }, body: JSON.stringify(setup),
+  }), { ...dependencies, observe: event => events.push(event), stack: { verify: async () => { throw new Error("private upstream detail"); } } });
+  expect(events).toEqual([expect.objectContaining({ route: "session", stage: "authenticate", operation: "none", cause: "Error" })]);
+});