From 09cc182addd4954d1c617b8eb1ec7d0616ebb793 Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Mon, 27 Apr 2026 15:58:58 +0000
Subject: [PATCH 01/21] feat: deprecate LogLevel.default and .error and remove
 all calls to those values.

---
 .../api-report/core-interfaces.beta.api.md    |  2 ++
 .../core-interfaces.legacy.alpha.api.md       |  2 ++
 .../core-interfaces.legacy.beta.api.md        |  2 ++
 .../core-interfaces.legacy.public.api.md      |  2 ++
 .../api-report/core-interfaces.public.api.md  |  2 ++
 packages/common/core-interfaces/src/logger.ts |  8 ++++----
 .../telemetry-utils.legacy.beta.api.md        |  4 ++--
 packages/utils/telemetry-utils/src/logger.ts  | 19 ++++++++++---------
 .../utils/telemetry-utils/src/mockLogger.ts   |  4 ++--
 .../telemetry-utils/src/telemetryTypes.ts     | 12 ++++++------
 .../src/test/childLogger.spec.ts              | 12 ++++++------
 .../src/test/multiSinkLogger.spec.ts          | 14 +++++++-------
 12 files changed, 47 insertions(+), 36 deletions(-)

diff --git a/packages/common/core-interfaces/api-report/core-interfaces.beta.api.md b/packages/common/core-interfaces/api-report/core-interfaces.beta.api.md
index 39a9b3379798..0562ed5986c8 100644
--- a/packages/common/core-interfaces/api-report/core-interfaces.beta.api.md
+++ b/packages/common/core-interfaces/api-report/core-interfaces.beta.api.md
@@ -333,7 +333,9 @@ export type LogLevel = (typeof LogLevel)[keyof typeof LogLevel];
 
 // @public
 export interface LogLevelConst {
+    // @deprecated
     readonly default: 20;
+    // @deprecated
     readonly error: 30;
     readonly essential: 30;
     readonly info: 20;
diff --git a/packages/common/core-interfaces/api-report/core-interfaces.legacy.alpha.api.md b/packages/common/core-interfaces/api-report/core-interfaces.legacy.alpha.api.md
index ef43fde81f7b..9378cbc5d36a 100644
--- a/packages/common/core-interfaces/api-report/core-interfaces.legacy.alpha.api.md
+++ b/packages/common/core-interfaces/api-report/core-interfaces.legacy.alpha.api.md
@@ -478,7 +478,9 @@ export type LogLevel = (typeof LogLevel)[keyof typeof LogLevel];
 
 // @public
 export interface LogLevelConst {
+    // @deprecated
     readonly default: 20;
+    // @deprecated
     readonly error: 30;
     readonly essential: 30;
     readonly info: 20;
diff --git a/packages/common/core-interfaces/api-report/core-interfaces.legacy.beta.api.md b/packages/common/core-interfaces/api-report/core-interfaces.legacy.beta.api.md
index cae6efefbae2..3975eeb54bfd 100644
--- a/packages/common/core-interfaces/api-report/core-interfaces.legacy.beta.api.md
+++ b/packages/common/core-interfaces/api-report/core-interfaces.legacy.beta.api.md
@@ -465,7 +465,9 @@ export type LogLevel = (typeof LogLevel)[keyof typeof LogLevel];
 
 // @public
 export interface LogLevelConst {
+    // @deprecated
     readonly default: 20;
+    // @deprecated
     readonly error: 30;
     readonly essential: 30;
     readonly info: 20;
diff --git a/packages/common/core-interfaces/api-report/core-interfaces.legacy.public.api.md b/packages/common/core-interfaces/api-report/core-interfaces.legacy.public.api.md
index 31e263d9e2c0..2f53560ad17c 100644
--- a/packages/common/core-interfaces/api-report/core-interfaces.legacy.public.api.md
+++ b/packages/common/core-interfaces/api-report/core-interfaces.legacy.public.api.md
@@ -333,7 +333,9 @@ export type LogLevel = (typeof LogLevel)[keyof typeof LogLevel];
 
 // @public
 export interface LogLevelConst {
+    // @deprecated
     readonly default: 20;
+    // @deprecated
     readonly error: 30;
     readonly essential: 30;
     readonly info: 20;
diff --git a/packages/common/core-interfaces/api-report/core-interfaces.public.api.md b/packages/common/core-interfaces/api-report/core-interfaces.public.api.md
index 31e263d9e2c0..2f53560ad17c 100644
--- a/packages/common/core-interfaces/api-report/core-interfaces.public.api.md
+++ b/packages/common/core-interfaces/api-report/core-interfaces.public.api.md
@@ -333,7 +333,9 @@ export type LogLevel = (typeof LogLevel)[keyof typeof LogLevel];
 
 // @public
 export interface LogLevelConst {
+    // @deprecated
     readonly default: 20;
+    // @deprecated
     readonly error: 30;
     readonly essential: 30;
     readonly info: 20;
diff --git a/packages/common/core-interfaces/src/logger.ts b/packages/common/core-interfaces/src/logger.ts
index 563d17182769..33a44a287890 100644
--- a/packages/common/core-interfaces/src/logger.ts
+++ b/packages/common/core-interfaces/src/logger.ts
@@ -81,13 +81,13 @@ export interface LogLevelConst {
 
 	/**
 	 * Default LogLevel
-	 * @remarks Prefer {@link LogLevelConst.info | LogLevel.info} when selecting a level explicitly since this will be deprecated and removed in a future release.
+	 * @deprecated Prefer {@link LogLevelConst.info | LogLevel.info} when selecting a level explicitly to preserve prior treatment.
 	 */
 	readonly default: 20;
 
 	/**
 	 * To log errors.
-	 * @remarks Prefer {@link LogLevelConst.essential | LogLevel.essential} when selecting a level since this will be deprecated and removed in a future release.
+	 * @deprecated Prefer {@link LogLevelConst.essential | LogLevel.essential} when selecting a level.
 	 */
 	readonly error: 30;
 }
@@ -120,13 +120,13 @@ export interface ITelemetryBaseLogger {
 	/**
 	 * Log a telemetry event, if it meets the appropriate log-level threshold (see {@link ITelemetryBaseLogger.minLogLevel}).
 	 * @param event - The event to log.
-	 * @param logLevel - The log level of the event. Default: {@link LogLevelConst.default | LogLevel.default}.
+	 * @param logLevel - The log level of the event. Default: {@link LogLevelConst.info | LogLevel.info}.
 	 */
 	send(event: ITelemetryBaseEvent, logLevel?: LogLevel): void;
 
 	/**
 	 * Minimum log level to be logged.
-	 * @defaultValue {@link LogLevelConst.default | LogLevel.default}.
+	 * @defaultValue {@link LogLevelConst.info | LogLevel.info}.
 	 */
 	minLogLevel?: LogLevel;
 }
diff --git a/packages/utils/telemetry-utils/api-report/telemetry-utils.legacy.beta.api.md b/packages/utils/telemetry-utils/api-report/telemetry-utils.legacy.beta.api.md
index 0d9251f8cc7e..1af6c1b4480a 100644
--- a/packages/utils/telemetry-utils/api-report/telemetry-utils.legacy.beta.api.md
+++ b/packages/utils/telemetry-utils/api-report/telemetry-utils.legacy.beta.api.md
@@ -34,9 +34,9 @@ export interface ITelemetryLoggerExt extends ITelemetryBaseLogger {
     // @deprecated
     sendErrorEvent(event: ITelemetryErrorEventExt, error?: unknown): void;
     // @deprecated
-    sendPerformanceEvent(event: ITelemetryPerformanceEventExt, error?: unknown, logLevel?: typeof LogLevel.verbose | typeof LogLevel.default): void;
+    sendPerformanceEvent(event: ITelemetryPerformanceEventExt, error?: unknown, logLevel?: typeof LogLevel.verbose | typeof LogLevel.info): void;
     // @deprecated
-    sendTelemetryEvent(event: ITelemetryGenericEventExt, error?: unknown, logLevel?: typeof LogLevel.verbose | typeof LogLevel.default): void;
+    sendTelemetryEvent(event: ITelemetryGenericEventExt, error?: unknown, logLevel?: typeof LogLevel.verbose | typeof LogLevel.info): void;
 }
 
 // @beta @legacy (undocumented)
diff --git a/packages/utils/telemetry-utils/src/logger.ts b/packages/utils/telemetry-utils/src/logger.ts
index ec49c2d36993..7ea05780904b 100644
--- a/packages/utils/telemetry-utils/src/logger.ts
+++ b/packages/utils/telemetry-utils/src/logger.ts
@@ -230,12 +230,12 @@ export abstract class TelemetryLogger implements TelemetryLoggerExt {
 	public sendTelemetryEvent(
 		event: ITelemetryGenericEventExt,
 		error?: unknown,
-		logLevel: typeof LogLevel.verbose | typeof LogLevel.default = LogLevel.default,
+		logLevel: typeof LogLevel.verbose | typeof LogLevel.info = LogLevel.info,
 	): void {
 		this.sendTelemetryEventCore(
 			{ ...event, category: event.category ?? "generic" },
 			error,
-			event.category === "error" ? LogLevel.error : logLevel,
+			event.category === "error" ? LogLevel.essential : logLevel,
 		);
 	}
 
@@ -280,7 +280,7 @@ export abstract class TelemetryLogger implements TelemetryLoggerExt {
 				category: "error",
 			},
 			error,
-			LogLevel.error,
+			LogLevel.essential,
 		);
 	}
 
@@ -295,7 +295,7 @@ export abstract class TelemetryLogger implements TelemetryLoggerExt {
 	public sendPerformanceEvent(
 		event: ITelemetryPerformanceEventExt,
 		error?: unknown,
-		logLevel: typeof LogLevel.verbose | typeof LogLevel.default = LogLevel.default,
+		logLevel: typeof LogLevel.verbose | typeof LogLevel.info = LogLevel.info,
 	): void {
 		const perfEvent = {
 			...event,
@@ -305,7 +305,7 @@ export abstract class TelemetryLogger implements TelemetryLoggerExt {
 		this.sendTelemetryEventCore(
 			perfEvent,
 			error,
-			perfEvent.category === "error" ? LogLevel.error : logLevel,
+			perfEvent.category === "error" ? LogLevel.essential : logLevel,
 		);
 	}
 
@@ -518,8 +518,9 @@ export class ChildLogger extends TelemetryLogger {
 	}
 
 	private shouldFilterOutEvent(event: ITelemetryBaseEvent, logLevel?: LogLevel): boolean {
-		const eventLogLevel = logLevel ?? LogLevel.default;
-		const configLogLevel = this.baseLogger.minLogLevel ?? LogLevel.default;
+		// Determine the log level of the event. If none is provided, default to essential
+		const eventLogLevel = logLevel ?? LogLevel.essential;
+		const configLogLevel = this.baseLogger.minLogLevel ?? LogLevel.info;
 		// Filter out in case event log level is below what is wanted in config.
 		return eventLogLevel < configLogLevel;
 	}
@@ -618,7 +619,7 @@ export class MultiSinkLogger extends TelemetryLogger {
 
 		super(namespace, realProperties);
 		this.loggers = loggers;
-		this._minLogLevelOfAllLoggers = LogLevel.default;
+		this._minLogLevelOfAllLoggers = LogLevel.info;
 		this.calculateMinLogLevel();
 	}
 
@@ -630,7 +631,7 @@ export class MultiSinkLogger extends TelemetryLogger {
 		if (this.loggers.length > 0) {
 			const logLevels: LogLevel[] = [];
 			for (const logger of this.loggers) {
-				logLevels.push(logger.minLogLevel ?? LogLevel.default);
+				logLevels.push(logger.minLogLevel ?? LogLevel.info);
 			}
 			this._minLogLevelOfAllLoggers = Math.min(...logLevels) as LogLevel;
 		}
diff --git a/packages/utils/telemetry-utils/src/mockLogger.ts b/packages/utils/telemetry-utils/src/mockLogger.ts
index cf52590cbdeb..a413c9e1b2d0 100644
--- a/packages/utils/telemetry-utils/src/mockLogger.ts
+++ b/packages/utils/telemetry-utils/src/mockLogger.ts
@@ -41,7 +41,7 @@ export class MockLogger implements ITelemetryBaseLogger {
 	public readonly minLogLevel: LogLevel;
 
 	public constructor(minLogLevel?: LogLevel) {
-		this.minLogLevel = minLogLevel ?? LogLevel.default;
+		this.minLogLevel = minLogLevel ?? LogLevel.info;
 	}
 
 	/**
@@ -59,7 +59,7 @@ export class MockLogger implements ITelemetryBaseLogger {
 	 * {@inheritDoc @fluidframework/core-interfaces#ITelemetryBaseLogger.send}
 	 */
 	public send(event: ITelemetryBaseEvent, logLevel?: LogLevel): void {
-		if ((logLevel ?? LogLevel.default) >= this.minLogLevel) {
+		if ((logLevel ?? LogLevel.info) >= this.minLogLevel) {
 			this._events.push(event);
 		}
 	}
diff --git a/packages/utils/telemetry-utils/src/telemetryTypes.ts b/packages/utils/telemetry-utils/src/telemetryTypes.ts
index 09270dfcf25f..ba79d132373a 100644
--- a/packages/utils/telemetry-utils/src/telemetryTypes.ts
+++ b/packages/utils/telemetry-utils/src/telemetryTypes.ts
@@ -143,7 +143,7 @@ export interface ITelemetryLoggerExt extends ITelemetryBaseLogger {
 	sendTelemetryEvent(
 		event: ITelemetryGenericEventExt,
 		error?: unknown,
-		logLevel?: typeof LogLevel.verbose | typeof LogLevel.default,
+		logLevel?: typeof LogLevel.verbose | typeof LogLevel.info,
 	): void;
 
 	/**
@@ -166,7 +166,7 @@ export interface ITelemetryLoggerExt extends ITelemetryBaseLogger {
 	sendPerformanceEvent(
 		event: ITelemetryPerformanceEventExt,
 		error?: unknown,
-		logLevel?: typeof LogLevel.verbose | typeof LogLevel.default,
+		logLevel?: typeof LogLevel.verbose | typeof LogLevel.info,
 	): void;
 }
 
@@ -183,12 +183,12 @@ export interface TelemetryLoggerExt extends ITelemetryBaseLogger {
 	 * Send an information telemetry event.
 	 * @param event - Event to send.
 	 * @param error - Optional error object to log.
-	 * @param logLevel - Optional level of the log. Default: {@link @fluidframework/core-interfaces#LogLevel.default}.
+	 * @param logLevel - Optional level of the log. Default: {@link @fluidframework/core-interfaces#LogLevelConst.info | LogLevel.info}.
 	 */
 	sendTelemetryEvent(
 		event: ITelemetryGenericEventExt,
 		error?: unknown,
-		logLevel?: typeof LogLevel.verbose | typeof LogLevel.default,
+		logLevel?: typeof LogLevel.verbose | typeof LogLevel.info,
 	): void;
 
 	/**
@@ -202,11 +202,11 @@ export interface TelemetryLoggerExt extends ITelemetryBaseLogger {
 	 * Send a performance telemetry event.
 	 * @param event - Event to send
 	 * @param error - Optional error object to log.
-	 * @param logLevel - Optional level of the log. Default: {@link @fluidframework/core-interfaces#LogLevelConst.default | LogLevel.default}.
+	 * @param logLevel - Optional level of the log. Default: {@link @fluidframework/core-interfaces#LogLevelConst.info | LogLevel.info}.
 	 */
 	sendPerformanceEvent(
 		event: ITelemetryPerformanceEventExt,
 		error?: unknown,
-		logLevel?: typeof LogLevel.verbose | typeof LogLevel.default,
+		logLevel?: typeof LogLevel.verbose | typeof LogLevel.info,
 	): void;
 }
diff --git a/packages/utils/telemetry-utils/src/test/childLogger.spec.ts b/packages/utils/telemetry-utils/src/test/childLogger.spec.ts
index be7e75d132b6..0bb1961bad34 100644
--- a/packages/utils/telemetry-utils/src/test/childLogger.spec.ts
+++ b/packages/utils/telemetry-utils/src/test/childLogger.spec.ts
@@ -194,15 +194,15 @@ describe("ChildLogger", () => {
 				sent = true;
 			},
 
-			minLogLevel: LogLevel.error,
+			minLogLevel: LogLevel.essential,
 		};
 		const childLogger1 = createChildLogger({ logger });
 
-		childLogger1.send({ category: "error", eventName: "testEvent" }, LogLevel.error);
+		childLogger1.send({ category: "error", eventName: "testEvent" }, LogLevel.essential);
 		assert(sent, "event should be sent");
 
 		sent = false;
-		childLogger1.send({ category: "generic", eventName: "testEvent" }, LogLevel.default);
+		childLogger1.send({ category: "generic", eventName: "testEvent" }, LogLevel.info);
 		assert(!sent, "event should not be sent");
 	});
 
@@ -257,10 +257,10 @@ describe("ChildLogger", () => {
 				}
 				sent = true;
 			},
-			minLogLevel: LogLevel.default,
+			minLogLevel: LogLevel.info,
 		};
 		const multiSinkLogger = createMultiSinkLogger({
-			loggers: [logger1, new MockLogger(LogLevel.error)],
+			loggers: [logger1, new MockLogger(LogLevel.essential)],
 		});
 		const childLogger1 = createChildLogger({
 			logger: multiSinkLogger,
@@ -269,7 +269,7 @@ describe("ChildLogger", () => {
 		childLogger1.send({ category: "generic", eventName: "testEvent" }, LogLevel.verbose);
 		assert(!sent, "verbose event should not be sent");
 
-		childLogger1.send({ category: "generic", eventName: "testEvent" }, LogLevel.default);
+		childLogger1.send({ category: "generic", eventName: "testEvent" }, LogLevel.info);
 		assert(sent, "default event should be sent");
 	});
 });
diff --git a/packages/utils/telemetry-utils/src/test/multiSinkLogger.spec.ts b/packages/utils/telemetry-utils/src/test/multiSinkLogger.spec.ts
index 74efa4ec3c14..1a899f599d31 100644
--- a/packages/utils/telemetry-utils/src/test/multiSinkLogger.spec.ts
+++ b/packages/utils/telemetry-utils/src/test/multiSinkLogger.spec.ts
@@ -66,14 +66,14 @@ describe("MultiSinkLogger", () => {
 	});
 
 	it("MultiSink logger set the logLevel to min logLevel of all loggers", () => {
-		const logger1 = new MockLogger(LogLevel.error);
-		const logger2 = new MockLogger(LogLevel.default);
+		const logger1 = new MockLogger(LogLevel.essential);
+		const logger2 = new MockLogger(LogLevel.info);
 		const multiSink = createMultiSinkLogger({
 			loggers: [createChildLogger({ logger: logger1 }), logger2],
 		});
 		assert.strictEqual(
 			multiSink.minLogLevel,
-			LogLevel.default,
+			LogLevel.info,
 			"Min loglevel should be set correctly",
 		);
 
@@ -94,7 +94,7 @@ describe("MultiSinkLogger", () => {
 		});
 		assert.strictEqual(
 			multiSink.minLogLevel,
-			LogLevel.default,
+			LogLevel.info,
 			"Min loglevel should be set correctly to default",
 		);
 	});
@@ -107,14 +107,14 @@ describe("MultiSinkLogger", () => {
 		(multiSink as MultiSinkLogger).addLogger(new MockLogger());
 		assert.strictEqual(
 			multiSink.minLogLevel,
-			LogLevel.default,
+			LogLevel.info,
 			"Min loglevel should be set correctly to default",
 		);
 
-		(multiSink as MultiSinkLogger).addLogger(new MockLogger(LogLevel.default));
+		(multiSink as MultiSinkLogger).addLogger(new MockLogger(LogLevel.info));
 		assert.strictEqual(
 			multiSink.minLogLevel,
-			LogLevel.default,
+			LogLevel.info,
 			"Min loglevel should be set correctly to default",
 		);
 

From 352567421e27859f858e1e3880bab3010e4f7283 Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Mon, 27 Apr 2026 16:10:34 +0000
Subject: [PATCH 02/21] feat: send LogLevel as undefined and default to
 essential on send logic

---
 packages/utils/telemetry-utils/src/logger.ts | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/packages/utils/telemetry-utils/src/logger.ts b/packages/utils/telemetry-utils/src/logger.ts
index 7ea05780904b..5991014865fd 100644
--- a/packages/utils/telemetry-utils/src/logger.ts
+++ b/packages/utils/telemetry-utils/src/logger.ts
@@ -230,7 +230,7 @@ export abstract class TelemetryLogger implements TelemetryLoggerExt {
 	public sendTelemetryEvent(
 		event: ITelemetryGenericEventExt,
 		error?: unknown,
-		logLevel: typeof LogLevel.verbose | typeof LogLevel.info = LogLevel.info,
+		logLevel?: typeof LogLevel.verbose | typeof LogLevel.info,
 	): void {
 		this.sendTelemetryEventCore(
 			{ ...event, category: event.category ?? "generic" },
@@ -295,7 +295,7 @@ export abstract class TelemetryLogger implements TelemetryLoggerExt {
 	public sendPerformanceEvent(
 		event: ITelemetryPerformanceEventExt,
 		error?: unknown,
-		logLevel: typeof LogLevel.verbose | typeof LogLevel.info = LogLevel.info,
+		logLevel?: typeof LogLevel.verbose | typeof LogLevel.info,
 	): void {
 		const perfEvent = {
 			...event,
@@ -534,7 +534,8 @@ export class ChildLogger extends TelemetryLogger {
 		if (this.shouldFilterOutEvent(event, logLevel)) {
 			return;
 		}
-		this.baseLogger.send(this.prepareEvent(event), logLevel);
+		// If no log level was provided, default to essential
+		this.baseLogger.send(this.prepareEvent(event), logLevel ?? LogLevel.essential);
 	}
 }
 

From 67614c8c4944280a003be5735de78ebb69b06ee3 Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Wed, 29 Apr 2026 22:36:19 +0000
Subject: [PATCH 03/21] refactor: properly ordered imports and removed
 LogLevel.default

---
 .../container-loader/src/test/container.spec.ts       |  3 ++-
 packages/utils/telemetry-utils/src/logger.ts          | 11 +++++++----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/packages/loader/container-loader/src/test/container.spec.ts b/packages/loader/container-loader/src/test/container.spec.ts
index cdeed1b6c545..f3a154e05391 100644
--- a/packages/loader/container-loader/src/test/container.spec.ts
+++ b/packages/loader/container-loader/src/test/container.spec.ts
@@ -9,7 +9,8 @@ import {
 	TypedEventEmitter,
 	type IProvideLayerCompatDetails,
 } from "@fluid-internal/client-utils";
-import { AttachState, type IAudience } from "@fluidframework/container-definitions";
+import type { IAudience } from "@fluidframework/container-definitions";
+import { AttachState } from "@fluidframework/container-definitions";
 import type {
 	ICriticalContainerError,
 	IContainer,
diff --git a/packages/utils/telemetry-utils/src/logger.ts b/packages/utils/telemetry-utils/src/logger.ts
index 1608bb1cdcc5..0d579154a22a 100644
--- a/packages/utils/telemetry-utils/src/logger.ts
+++ b/packages/utils/telemetry-utils/src/logger.ts
@@ -695,6 +695,7 @@ export class PerformanceEvent {
 	 * @param emitLogs - should this instance emit logs. If set to false, logs will not be emitted to the logger,
 	 * but measurements will still be performed and any specified markers will be generated.
 	 * @param logLevel - optional {@link LogLevel} for events emitted by this performance event.
+	 * If unspecified, {@link @fluidframework/core-interfaces#LogLevelConst.default | LogLevel.default} will be used.
 	 * @returns An instance of {@link PerformanceEvent}
 	 */
 	public static start(
@@ -702,7 +703,7 @@ export class PerformanceEvent {
 		event: ITelemetryGenericEventExt,
 		markers?: IPerformanceEventMarkers,
 		emitLogs: boolean = true,
-		logLevel?: typeof LogLevel.verbose | typeof LogLevel.default,
+		logLevel?: typeof LogLevel.verbose | typeof LogLevel.info,
 	): PerformanceEvent {
 		return new PerformanceEvent(
 			extractTelemetryLoggerExt(logger),
@@ -722,6 +723,7 @@ export class PerformanceEvent {
 	 * @param sampleThreshold - events with the same name and category will be sent to the logger
 	 * only when we hit this many executions of the task. If unspecified, all events will be sent.
 	 * @param logLevel - optional {@link LogLevel} for events emitted by this performance event.
+	 * If unspecified, {@link @fluidframework/core-interfaces#LogLevelConst.info | LogLevel.info} will be used.
 	 * @returns The results of the executed task
 	 *
 	 * @remarks Note that if the "same" event (category + eventName) would be emitted by different
@@ -735,7 +737,7 @@ export class PerformanceEvent {
 		callback: (event: PerformanceEvent) => T,
 		markers?: IPerformanceEventMarkers,
 		sampleThreshold: number = 1,
-		logLevel?: typeof LogLevel.verbose | typeof LogLevel.default,
+		logLevel?: typeof LogLevel.verbose | typeof LogLevel.info,
 	): T {
 		const perfEvent = PerformanceEvent.start(
 			logger,
@@ -764,6 +766,7 @@ export class PerformanceEvent {
 	 * @param sampleThreshold - events with the same name and category will be sent to the logger
 	 * only when we hit this many executions of the task. If unspecified, all events will be sent.
 	 * @param logLevel - optional {@link LogLevel} for events emitted by this performance event.
+	 * If unspecified, {@link @fluidframework/core-interfaces#LogLevelConst.default | LogLevel.default} will be used.
 	 * @returns The results of the executed task
 	 *
 	 * @remarks Note that if the "same" event (category + eventName) would be emitted by different
@@ -777,7 +780,7 @@ export class PerformanceEvent {
 		callback: (event: PerformanceEvent) => Promise<T>,
 		markers?: IPerformanceEventMarkers,
 		sampleThreshold: number = 1,
-		logLevel?: typeof LogLevel.verbose | typeof LogLevel.default,
+		logLevel?: typeof LogLevel.verbose | typeof LogLevel.info,
 	): Promise<T> {
 		const perfEvent = PerformanceEvent.start(
 			logger,
@@ -809,7 +812,7 @@ export class PerformanceEvent {
 		event: ITelemetryGenericEventExt,
 		private readonly markers: IPerformanceEventMarkers = { end: true, cancel: "generic" },
 		private readonly emitLogs: boolean = true,
-		private readonly logLevel?: typeof LogLevel.verbose | typeof LogLevel.default,
+		private readonly logLevel?: typeof LogLevel.verbose | typeof LogLevel.info,
 	) {
 		this.event = { ...event };
 		if (this.markers.start) {

From a568d12a27045c26d52161761c36fdca389044aa Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Wed, 29 Apr 2026 22:39:15 +0000
Subject: [PATCH 04/21] docs: fixed comments

---
 packages/utils/telemetry-utils/src/logger.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/utils/telemetry-utils/src/logger.ts b/packages/utils/telemetry-utils/src/logger.ts
index 0d579154a22a..ff151144c0e4 100644
--- a/packages/utils/telemetry-utils/src/logger.ts
+++ b/packages/utils/telemetry-utils/src/logger.ts
@@ -695,7 +695,7 @@ export class PerformanceEvent {
 	 * @param emitLogs - should this instance emit logs. If set to false, logs will not be emitted to the logger,
 	 * but measurements will still be performed and any specified markers will be generated.
 	 * @param logLevel - optional {@link LogLevel} for events emitted by this performance event.
-	 * If unspecified, {@link @fluidframework/core-interfaces#LogLevelConst.default | LogLevel.default} will be used.
+	 * If unspecified, {@link @fluidframework/core-interfaces#LogLevelConst.info | LogLevel.info} will be used.
 	 * @returns An instance of {@link PerformanceEvent}
 	 */
 	public static start(
@@ -766,7 +766,7 @@ export class PerformanceEvent {
 	 * @param sampleThreshold - events with the same name and category will be sent to the logger
 	 * only when we hit this many executions of the task. If unspecified, all events will be sent.
 	 * @param logLevel - optional {@link LogLevel} for events emitted by this performance event.
-	 * If unspecified, {@link @fluidframework/core-interfaces#LogLevelConst.default | LogLevel.default} will be used.
+	 * If unspecified, {@link @fluidframework/core-interfaces#LogLevelConst.info | LogLevel.info} will be used.
 	 * @returns The results of the executed task
 	 *
 	 * @remarks Note that if the "same" event (category + eventName) would be emitted by different

From 9a816820ae973cca94d69db3fbe60f93e62ad465 Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Wed, 29 Apr 2026 22:47:13 +0000
Subject: [PATCH 05/21] docs: updated docs

---
 packages/common/core-interfaces/src/logger.ts | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/packages/common/core-interfaces/src/logger.ts b/packages/common/core-interfaces/src/logger.ts
index 33a44a287890..a42bb69911b0 100644
--- a/packages/common/core-interfaces/src/logger.ts
+++ b/packages/common/core-interfaces/src/logger.ts
@@ -82,12 +82,14 @@ export interface LogLevelConst {
 	/**
 	 * Default LogLevel
 	 * @deprecated Prefer {@link LogLevelConst.info | LogLevel.info} when selecting a level explicitly to preserve prior treatment.
+	 * @see {@link https://github.com/microsoft/FluidFramework/issues/26969 | Issue #26969} for removal tracking.
 	 */
 	readonly default: 20;
 
 	/**
 	 * To log errors.
 	 * @deprecated Prefer {@link LogLevelConst.essential | LogLevel.essential} when selecting a level.
+	 * @see {@link https://github.com/microsoft/FluidFramework/issues/26969 | Issue #26969} for removal tracking.
 	 */
 	readonly error: 30;
 }

From da948a1b26cf7307ebc532b37beebee735154474 Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Wed, 29 Apr 2026 23:24:50 +0000
Subject: [PATCH 06/21] docs: added changesets

---
 .changeset/salty-colts-appear.md | 15 +++++++++++++++
 .changeset/soft-doors-trade.md   | 20 ++++++++++++++++++++
 2 files changed, 35 insertions(+)
 create mode 100644 .changeset/salty-colts-appear.md
 create mode 100644 .changeset/soft-doors-trade.md

diff --git a/.changeset/salty-colts-appear.md b/.changeset/salty-colts-appear.md
new file mode 100644
index 000000000000..29047d214ebe
--- /dev/null
+++ b/.changeset/salty-colts-appear.md
@@ -0,0 +1,15 @@
+---
+"@fluidframework/core-interfaces": minor
+"__section": deprecation
+---
+
+Deprecated LogLevel.default and LogLevel.error
+
+`LogLevel.default` and `LogLevel.error` in `@fluidframework/core-interfaces` are deprecated in favor of the semantically clearer `LogLevel.info` and `LogLevel.essential` respectively.
+
+#### Migration
+
+- `LogLevel.default` (= `20`) → use `LogLevel.info`
+- `LogLevel.error` (= `30`) → use `LogLevel.essential`
+
+Removal is tracked in [issue #26969](https://github.com/microsoft/FluidFramework/issues/26969) and is planned for the v3.0 major release.
diff --git a/.changeset/soft-doors-trade.md b/.changeset/soft-doors-trade.md
new file mode 100644
index 000000000000..7c3370f6590f
--- /dev/null
+++ b/.changeset/soft-doors-trade.md
@@ -0,0 +1,20 @@
+---
+"@fluidframework/telemetry-utils": minor
+"__section": other
+---
+
+ChildLogger now tags events with no explicit `logLevel` as `essential`
+
+`@fluidframework/telemetry-utils` previously forwarded events with no explicit `logLevel` to the base logger as `undefined` (effectively treated as `LogLevel.info` = `20`). It now forwards them as `LogLevel.essential` (= `30`). Specifically:
+
+- `ChildLogger.shouldFilterOutEvent` now falls back to `LogLevel.essential` when an event has no `logLevel` (previously fell back to `LogLevel.default` = `LogLevel.info` = `20`).
+- `ChildLogger.send` now forwards `LogLevel.essential` to the base logger when no `logLevel` is supplied, instead of forwarding `undefined`.
+- The implicit `= LogLevel.default` parameter defaults on `TelemetryLogger.sendTelemetryEvent` and `sendPerformanceEvent` were removed; callers that omit `logLevel` now propagate `undefined` through the chain, where `ChildLogger` applies the new `essential` fallback above.
+
+#### Impact for downstream consumers
+
+Internal Fluid events that previously arrived at the base logger with `logLevel = undefined` will now arrive tagged as `30` (`essential`). Hosts that filter telemetry by numeric level should not start dropping `logLevel = 20` events as "non-essential" unless **all** running Fluid versions include this change — older versions still send those same critical events at level `20`, and dropping them would lose telemetry.
+
+#### Events already explicitly tagged as `LogLevel.info`
+
+Note that this change only affects events emitted with **no** explicit `logLevel`. A set of events that are already explicitly tagged with `LogLevel.info` (= `20`) was introduced in [PR #27126](https://github.com/microsoft/FluidFramework/pull/27126) and is unaffected by this change — those events continue to be emitted at level `20` by design and are the intended target for hosts that want to drop non-essential telemetry once all running Fluid versions include both PR #27126 and this change.

From c0d93962b0092c3b93387bfe25de47998bba8065 Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Wed, 29 Apr 2026 23:38:37 +0000
Subject: [PATCH 07/21] docs: added removal timeline

---
 packages/common/core-interfaces/src/logger.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/common/core-interfaces/src/logger.ts b/packages/common/core-interfaces/src/logger.ts
index a42bb69911b0..cde2687216b9 100644
--- a/packages/common/core-interfaces/src/logger.ts
+++ b/packages/common/core-interfaces/src/logger.ts
@@ -81,14 +81,14 @@ export interface LogLevelConst {
 
 	/**
 	 * Default LogLevel
-	 * @deprecated Prefer {@link LogLevelConst.info | LogLevel.info} when selecting a level explicitly to preserve prior treatment.
+	 * @deprecated 2.101.0. Removed in 3.0.0. Prefer {@link LogLevelConst.info | LogLevel.info} when selecting a level explicitly to preserve prior treatment.
 	 * @see {@link https://github.com/microsoft/FluidFramework/issues/26969 | Issue #26969} for removal tracking.
 	 */
 	readonly default: 20;
 
 	/**
 	 * To log errors.
-	 * @deprecated Prefer {@link LogLevelConst.essential | LogLevel.essential} when selecting a level.
+	 * @deprecated 2.101.0. Removed in 3.0.0. Prefer {@link LogLevelConst.essential | LogLevel.essential} when selecting a level.
 	 * @see {@link https://github.com/microsoft/FluidFramework/issues/26969 | Issue #26969} for removal tracking.
 	 */
 	readonly error: 30;

From f3a92b6010bedaecbc030ca618c74301f524dc80 Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Wed, 29 Apr 2026 23:39:42 +0000
Subject: [PATCH 08/21] docs: updated deprecation message

---
 packages/common/core-interfaces/src/logger.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/common/core-interfaces/src/logger.ts b/packages/common/core-interfaces/src/logger.ts
index cde2687216b9..ab32c3b9a7de 100644
--- a/packages/common/core-interfaces/src/logger.ts
+++ b/packages/common/core-interfaces/src/logger.ts
@@ -81,14 +81,14 @@ export interface LogLevelConst {
 
 	/**
 	 * Default LogLevel
-	 * @deprecated 2.101.0. Removed in 3.0.0. Prefer {@link LogLevelConst.info | LogLevel.info} when selecting a level explicitly to preserve prior treatment.
+	 * @deprecated Prefer {@link LogLevelConst.info | LogLevel.info} when selecting a level explicitly to preserve prior treatment. Planned to be removed in 3.0.0.
 	 * @see {@link https://github.com/microsoft/FluidFramework/issues/26969 | Issue #26969} for removal tracking.
 	 */
 	readonly default: 20;
 
 	/**
 	 * To log errors.
-	 * @deprecated 2.101.0. Removed in 3.0.0. Prefer {@link LogLevelConst.essential | LogLevel.essential} when selecting a level.
+	 * @deprecated Prefer {@link LogLevelConst.essential | LogLevel.essential} when selecting a level. Planned to be removed in 3.0.0.
 	 * @see {@link https://github.com/microsoft/FluidFramework/issues/26969 | Issue #26969} for removal tracking.
 	 */
 	readonly error: 30;

From 0ba1037734cce7a3a5b7f274e7f962b3a259a372 Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Mon, 4 May 2026 22:04:24 +0000
Subject: [PATCH 09/21] docs: addressed docs comments

---
 .changeset/soft-doors-trade.md | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/.changeset/soft-doors-trade.md b/.changeset/soft-doors-trade.md
index 7c3370f6590f..97d6ed157f96 100644
--- a/.changeset/soft-doors-trade.md
+++ b/.changeset/soft-doors-trade.md
@@ -5,7 +5,7 @@
 
 ChildLogger now tags events with no explicit `logLevel` as `essential`
 
-`@fluidframework/telemetry-utils` previously forwarded events with no explicit `logLevel` to the base logger as `undefined` (effectively treated as `LogLevel.info` = `20`). It now forwards them as `LogLevel.essential` (= `30`). Specifically:
+`@fluidframework/telemetry-utils` previously forwarded events with no explicit `logLevel` to the base logger as `undefined` (treated as `LogLevel.info` = `20`). It now forwards them as `LogLevel.essential` (= `30`). Specifically:
 
 - `ChildLogger.shouldFilterOutEvent` now falls back to `LogLevel.essential` when an event has no `logLevel` (previously fell back to `LogLevel.default` = `LogLevel.info` = `20`).
 - `ChildLogger.send` now forwards `LogLevel.essential` to the base logger when no `logLevel` is supplied, instead of forwarding `undefined`.
@@ -13,8 +13,8 @@ ChildLogger now tags events with no explicit `logLevel` as `essential`
 
 #### Impact for downstream consumers
 
-Internal Fluid events that previously arrived at the base logger with `logLevel = undefined` will now arrive tagged as `30` (`essential`). Hosts that filter telemetry by numeric level should not start dropping `logLevel = 20` events as "non-essential" unless **all** running Fluid versions include this change — older versions still send those same critical events at level `20`, and dropping them would lose telemetry.
+Internal Fluid events that previously arrived at the base logger with `logLevel = undefined` will now arrive tagged as `30` (`essential`). Hosts that filter telemetry by numeric level should not start dropping `logLevel = 20` events as "non-essential" unless **all** running Fluid versions include this change. Older versions still send those same critical events at level `20`, and dropping them would lose telemetry.
 
 #### Events already explicitly tagged as `LogLevel.info`
 
-Note that this change only affects events emitted with **no** explicit `logLevel`. A set of events that are already explicitly tagged with `LogLevel.info` (= `20`) was introduced in [PR #27126](https://github.com/microsoft/FluidFramework/pull/27126) and is unaffected by this change — those events continue to be emitted at level `20` by design and are the intended target for hosts that want to drop non-essential telemetry once all running Fluid versions include both PR #27126 and this change.
+Note that this change only affects events emitted with **no** explicit `logLevel`. A set of events that are already explicitly tagged with `LogLevel.info` (= `20`) was introduced in [PR #27126](https://github.com/microsoft/FluidFramework/pull/27126) and is unaffected by this change. Those events continue to be emitted at level `20` by design and are the intended target for hosts that want to drop non-essential telemetry once all running Fluid versions include both PR #27126 and this change.

From 5f1205d803f9a6460ae1fec39cd7cb001ded4844 Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Tue, 5 May 2026 20:07:40 +0000
Subject: [PATCH 10/21] docs: updated chengeset title

---
 .changeset/soft-doors-trade.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.changeset/soft-doors-trade.md b/.changeset/soft-doors-trade.md
index 97d6ed157f96..02d2148c7fcc 100644
--- a/.changeset/soft-doors-trade.md
+++ b/.changeset/soft-doors-trade.md
@@ -3,7 +3,7 @@
 "__section": other
 ---
 
-ChildLogger now tags events with no explicit `logLevel` as `essential`
+ChildLogger now tags events with no explicit logLevel as essential
 
 `@fluidframework/telemetry-utils` previously forwarded events with no explicit `logLevel` to the base logger as `undefined` (treated as `LogLevel.info` = `20`). It now forwards them as `LogLevel.essential` (= `30`). Specifically:
 

From ba3935869644259374aa92efbce07208121b6776 Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Tue, 5 May 2026 20:17:21 +0000
Subject: [PATCH 11/21] feat: applied changes to docs and code based on
 comments

---
 packages/common/core-interfaces/src/logger.ts              | 2 +-
 packages/utils/telemetry-utils/src/logger.ts               | 7 ++++---
 packages/utils/telemetry-utils/src/telemetryTypes.ts       | 4 ++--
 .../utils/telemetry-utils/src/test/childLogger.spec.ts     | 4 ++++
 4 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/packages/common/core-interfaces/src/logger.ts b/packages/common/core-interfaces/src/logger.ts
index ab32c3b9a7de..aafe1e4a4f2e 100644
--- a/packages/common/core-interfaces/src/logger.ts
+++ b/packages/common/core-interfaces/src/logger.ts
@@ -122,7 +122,7 @@ export interface ITelemetryBaseLogger {
 	/**
 	 * Log a telemetry event, if it meets the appropriate log-level threshold (see {@link ITelemetryBaseLogger.minLogLevel}).
 	 * @param event - The event to log.
-	 * @param logLevel - The log level of the event. Default: {@link LogLevelConst.info | LogLevel.info}.
+	 * @param logLevel - The log level of the event. If undefined, the event will be sent with {@link LogLevelConst.essential | LogLevel.essential}.
 	 */
 	send(event: ITelemetryBaseEvent, logLevel?: LogLevel): void;
 
diff --git a/packages/utils/telemetry-utils/src/logger.ts b/packages/utils/telemetry-utils/src/logger.ts
index ff151144c0e4..b54b106fd061 100644
--- a/packages/utils/telemetry-utils/src/logger.ts
+++ b/packages/utils/telemetry-utils/src/logger.ts
@@ -695,7 +695,7 @@ export class PerformanceEvent {
 	 * @param emitLogs - should this instance emit logs. If set to false, logs will not be emitted to the logger,
 	 * but measurements will still be performed and any specified markers will be generated.
 	 * @param logLevel - optional {@link LogLevel} for events emitted by this performance event.
-	 * If unspecified, {@link @fluidframework/core-interfaces#LogLevelConst.info | LogLevel.info} will be used.
+	 * If unspecified, {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential} will be used.
 	 * @returns An instance of {@link PerformanceEvent}
 	 */
 	public static start(
@@ -723,7 +723,7 @@ export class PerformanceEvent {
 	 * @param sampleThreshold - events with the same name and category will be sent to the logger
 	 * only when we hit this many executions of the task. If unspecified, all events will be sent.
 	 * @param logLevel - optional {@link LogLevel} for events emitted by this performance event.
-	 * If unspecified, {@link @fluidframework/core-interfaces#LogLevelConst.info | LogLevel.info} will be used.
+	 * If unspecified, {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential} will be used.
 	 * @returns The results of the executed task
 	 *
 	 * @remarks Note that if the "same" event (category + eventName) would be emitted by different
@@ -766,7 +766,8 @@ export class PerformanceEvent {
 	 * @param sampleThreshold - events with the same name and category will be sent to the logger
 	 * only when we hit this many executions of the task. If unspecified, all events will be sent.
 	 * @param logLevel - optional {@link LogLevel} for events emitted by this performance event.
-	 * If unspecified, {@link @fluidframework/core-interfaces#LogLevelConst.info | LogLevel.info} will be used.
+	 * If unspecified, the `logLevel` property is left unset and the effective default is determined by
+	 * the logger implementation.
 	 * @returns The results of the executed task
 	 *
 	 * @remarks Note that if the "same" event (category + eventName) would be emitted by different
diff --git a/packages/utils/telemetry-utils/src/telemetryTypes.ts b/packages/utils/telemetry-utils/src/telemetryTypes.ts
index ba79d132373a..b9b0c6ca3ac3 100644
--- a/packages/utils/telemetry-utils/src/telemetryTypes.ts
+++ b/packages/utils/telemetry-utils/src/telemetryTypes.ts
@@ -183,7 +183,7 @@ export interface TelemetryLoggerExt extends ITelemetryBaseLogger {
 	 * Send an information telemetry event.
 	 * @param event - Event to send.
 	 * @param error - Optional error object to log.
-	 * @param logLevel - Optional level of the log. Default: {@link @fluidframework/core-interfaces#LogLevelConst.info | LogLevel.info}.
+	 * @param logLevel - Optional level of the log. If undefined, the event will be sent with {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential}.
 	 */
 	sendTelemetryEvent(
 		event: ITelemetryGenericEventExt,
@@ -202,7 +202,7 @@ export interface TelemetryLoggerExt extends ITelemetryBaseLogger {
 	 * Send a performance telemetry event.
 	 * @param event - Event to send
 	 * @param error - Optional error object to log.
-	 * @param logLevel - Optional level of the log. Default: {@link @fluidframework/core-interfaces#LogLevelConst.info | LogLevel.info}.
+	 * @param logLevel - Optional level of the log. If undefined, the event will be sent with {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential}.
 	 */
 	sendPerformanceEvent(
 		event: ITelemetryPerformanceEventExt,
diff --git a/packages/utils/telemetry-utils/src/test/childLogger.spec.ts b/packages/utils/telemetry-utils/src/test/childLogger.spec.ts
index 0bb1961bad34..27a7d1413962 100644
--- a/packages/utils/telemetry-utils/src/test/childLogger.spec.ts
+++ b/packages/utils/telemetry-utils/src/test/childLogger.spec.ts
@@ -204,6 +204,10 @@ describe("ChildLogger", () => {
 		sent = false;
 		childLogger1.send({ category: "generic", eventName: "testEvent" }, LogLevel.info);
 		assert(!sent, "event should not be sent");
+
+		sent = false;
+		childLogger1.send({ category: "generic", eventName: "testEvent" });
+		assert(sent, "default event should be sent");
 	});
 
 	it("should receive verbose events with min loglevel set as verbose", () => {

From bad57744d48d199f43b4070b33ae58e6853856ba Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Wed, 6 May 2026 17:20:26 +0000
Subject: [PATCH 12/21] feat: made logLevel required in various levels and
 added tests

---
 .changeset/soft-doors-trade.md                |   2 +-
 packages/utils/telemetry-utils/src/logger.ts  |  35 +++--
 .../src/test/childLogger.spec.ts              |   8 +-
 .../src/test/multiSinkLogger.spec.ts          | 140 +++++++++++++++++-
 .../telemetry-utils/src/test/utils.spec.ts    |  78 +++++++++-
 packages/utils/telemetry-utils/src/utils.ts   |  26 ++--
 6 files changed, 255 insertions(+), 34 deletions(-)

diff --git a/.changeset/soft-doors-trade.md b/.changeset/soft-doors-trade.md
index 02d2148c7fcc..9ce0479f8a40 100644
--- a/.changeset/soft-doors-trade.md
+++ b/.changeset/soft-doors-trade.md
@@ -3,7 +3,7 @@
 "__section": other
 ---
 
-ChildLogger now tags events with no explicit logLevel as essential
+All internal implementations of ITelemetryLoggerExt now tag events with no explicit logLevel as essential
 
 `@fluidframework/telemetry-utils` previously forwarded events with no explicit `logLevel` to the base logger as `undefined` (treated as `LogLevel.info` = `20`). It now forwards them as `LogLevel.essential` (= `30`). Specifically:
 
diff --git a/packages/utils/telemetry-utils/src/logger.ts b/packages/utils/telemetry-utils/src/logger.ts
index b54b106fd061..5f77f39c0895 100644
--- a/packages/utils/telemetry-utils/src/logger.ts
+++ b/packages/utils/telemetry-utils/src/logger.ts
@@ -217,7 +217,7 @@ export abstract class TelemetryLogger implements TelemetryLoggerExt {
 	 *
 	 * @param event - the event to send
 	 */
-	public abstract send(event: ITelemetryBaseEvent, logLevel?: LogLevel): void;
+	public abstract send(event: ITelemetryBaseEvent, logLevel: LogLevel): void;
 
 	/**
 	 * Send a telemetry event with the logger
@@ -230,7 +230,10 @@ export abstract class TelemetryLogger implements TelemetryLoggerExt {
 	public sendTelemetryEvent(
 		event: ITelemetryGenericEventExt,
 		error?: unknown,
-		logLevel?: typeof LogLevel.verbose | typeof LogLevel.info,
+		logLevel:
+			| typeof LogLevel.verbose
+			| typeof LogLevel.info
+			| typeof LogLevel.essential = LogLevel.essential,
 	): void {
 		this.sendTelemetryEventCore(
 			{ ...event, category: event.category ?? "generic" },
@@ -244,12 +247,12 @@ export abstract class TelemetryLogger implements TelemetryLoggerExt {
 	 *
 	 * @param event - the event to send
 	 * @param error - optional error object to log
-	 * @param logLevel - optional level of the log.
+	 * @param logLevel - level of the log.
 	 */
-	protected sendTelemetryEventCore(
+	private sendTelemetryEventCore(
 		event: ITelemetryGenericEventExt & { category: TelemetryEventCategory },
-		error?: unknown,
-		logLevel?: LogLevel,
+		error: unknown,
+		logLevel: LogLevel,
 	): void {
 		const newEvent = convertToBaseEvent(event);
 		if (error !== undefined) {
@@ -295,7 +298,10 @@ export abstract class TelemetryLogger implements TelemetryLoggerExt {
 	public sendPerformanceEvent(
 		event: ITelemetryPerformanceEventExt,
 		error?: unknown,
-		logLevel?: typeof LogLevel.verbose | typeof LogLevel.info,
+		logLevel:
+			| typeof LogLevel.verbose
+			| typeof LogLevel.info
+			| typeof LogLevel.essential = LogLevel.essential,
 	): void {
 		const perfEvent = {
 			...event,
@@ -517,9 +523,9 @@ export class ChildLogger extends TelemetryLogger {
 		return this.baseLogger.minLogLevel;
 	}
 
-	private shouldFilterOutEvent(event: ITelemetryBaseEvent, logLevel?: LogLevel): boolean {
-		// Determine the log level of the event. If none is provided, default to essential
-		const eventLogLevel = logLevel ?? LogLevel.essential;
+	private shouldFilterOutEvent(event: ITelemetryBaseEvent, logLevel: LogLevel): boolean {
+		// Determine the log level of the event. The log level is now required, so it will always be provided.
+		const eventLogLevel = logLevel;
 		const configLogLevel = this.baseLogger.minLogLevel ?? LogLevel.info;
 		// Filter out in case event log level is below what is wanted in config.
 		return eventLogLevel < configLogLevel;
@@ -530,12 +536,11 @@ export class ChildLogger extends TelemetryLogger {
 	 *
 	 * @param event - the event to send
 	 */
-	public send(event: ITelemetryBaseEvent, logLevel?: LogLevel): void {
+	public send(event: ITelemetryBaseEvent, logLevel: LogLevel): void {
 		if (this.shouldFilterOutEvent(event, logLevel)) {
 			return;
 		}
-		// If no log level was provided, default to essential
-		this.baseLogger.send(this.prepareEvent(event), logLevel ?? LogLevel.essential);
+		this.baseLogger.send(this.prepareEvent(event), logLevel);
 	}
 }
 
@@ -655,10 +660,10 @@ export class MultiSinkLogger extends TelemetryLogger {
 	 *
 	 * @param event - the event to send to all the registered logger
 	 */
-	public send(event: ITelemetryBaseEvent): void {
+	public send(event: ITelemetryBaseEvent, logLevel: LogLevel): void {
 		const newEvent = this.prepareEvent(event);
 		for (const logger of this.loggers) {
-			logger.send(newEvent);
+			logger.send(newEvent, logLevel);
 		}
 	}
 }
diff --git a/packages/utils/telemetry-utils/src/test/childLogger.spec.ts b/packages/utils/telemetry-utils/src/test/childLogger.spec.ts
index 27a7d1413962..19a5e3fb932f 100644
--- a/packages/utils/telemetry-utils/src/test/childLogger.spec.ts
+++ b/packages/utils/telemetry-utils/src/test/childLogger.spec.ts
@@ -32,7 +32,7 @@ describe("ChildLogger", () => {
 			},
 		});
 
-		childLogger1.send({ category: "generic", eventName: "test1" });
+		childLogger1.send({ category: "generic", eventName: "test1" }, LogLevel.essential);
 		assert(sent, "event should be sent");
 
 		sent = false;
@@ -65,7 +65,7 @@ describe("ChildLogger", () => {
 			},
 		});
 
-		childLogger2.send({ category: "generic", eventName: "testEvent" });
+		childLogger2.send({ category: "generic", eventName: "testEvent" }, LogLevel.essential);
 		assert(sent, "event should be sent");
 	});
 
@@ -94,7 +94,7 @@ describe("ChildLogger", () => {
 			},
 		});
 
-		childLogger2.send({ category: "generic", eventName: "testEvent" });
+		childLogger2.send({ category: "generic", eventName: "testEvent" }, LogLevel.essential);
 		assert(sent, "event should be sent");
 	});
 
@@ -123,7 +123,7 @@ describe("ChildLogger", () => {
 			},
 		});
 
-		childLogger2.send({ category: "generic", eventName: "testEvent" });
+		childLogger2.send({ category: "generic", eventName: "testEvent" }, LogLevel.essential);
 		assert(sent, "event should be sent");
 	});
 
diff --git a/packages/utils/telemetry-utils/src/test/multiSinkLogger.spec.ts b/packages/utils/telemetry-utils/src/test/multiSinkLogger.spec.ts
index 1a899f599d31..11ed26bd2c8e 100644
--- a/packages/utils/telemetry-utils/src/test/multiSinkLogger.spec.ts
+++ b/packages/utils/telemetry-utils/src/test/multiSinkLogger.spec.ts
@@ -5,11 +5,34 @@
 
 import { strict as assert } from "node:assert";
 
-import { LogLevel } from "@fluidframework/core-interfaces";
+import {
+	type ITelemetryBaseEvent,
+	type ITelemetryBaseLogger,
+	LogLevel,
+} from "@fluidframework/core-interfaces";
 
 import { type MultiSinkLogger, createChildLogger, createMultiSinkLogger } from "../logger.js";
 import { MockLogger } from "../mockLogger.js";
 
+interface RecordedEntry {
+	event: ITelemetryBaseEvent;
+	logLevel: LogLevel | undefined;
+}
+
+function createRecordingSink(minLogLevel: LogLevel = LogLevel.verbose): {
+	sink: ITelemetryBaseLogger;
+	recorded: RecordedEntry[];
+} {
+	const recorded: RecordedEntry[] = [];
+	const sink: ITelemetryBaseLogger = {
+		send: (event, logLevel): void => {
+			recorded.push({ event, logLevel });
+		},
+		minLogLevel,
+	};
+	return { sink, recorded };
+}
+
 describe("MultiSinkLogger", () => {
 	it("Pushes logs to all sinks", () => {
 		const logger1 = new MockLogger();
@@ -125,4 +148,119 @@ describe("MultiSinkLogger", () => {
 			"Min loglevel should be set correctly to verbose",
 		);
 	});
+
+	describe("logLevel propagation", () => {
+		it("Forwards LogLevel.essential to every sink when sendTelemetryEvent omits logLevel", () => {
+			const { sink: sinkA, recorded: recordedA } = createRecordingSink();
+			const { sink: sinkB, recorded: recordedB } = createRecordingSink();
+			const multiSink = createMultiSinkLogger({ loggers: [sinkA, sinkB] });
+
+			multiSink.sendTelemetryEvent({ eventName: "noLogLevel" });
+
+			assert.strictEqual(recordedA.length, 1);
+			assert.strictEqual(recordedB.length, 1);
+			assert.strictEqual(recordedA[0]?.logLevel, LogLevel.essential);
+			assert.strictEqual(recordedB[0]?.logLevel, LogLevel.essential);
+		});
+
+		it("Forwards LogLevel.essential to every sink when sendPerformanceEvent omits logLevel", () => {
+			const { sink: sinkA, recorded: recordedA } = createRecordingSink();
+			const { sink: sinkB, recorded: recordedB } = createRecordingSink();
+			const multiSink = createMultiSinkLogger({ loggers: [sinkA, sinkB] });
+
+			multiSink.sendPerformanceEvent({ eventName: "perfNoLogLevel" });
+
+			assert.strictEqual(recordedA[0]?.logLevel, LogLevel.essential);
+			assert.strictEqual(recordedB[0]?.logLevel, LogLevel.essential);
+		});
+
+		it("Forwards LogLevel.essential to every sink for sendErrorEvent", () => {
+			const { sink: sinkA, recorded: recordedA } = createRecordingSink();
+			const { sink: sinkB, recorded: recordedB } = createRecordingSink();
+			const multiSink = createMultiSinkLogger({ loggers: [sinkA, sinkB] });
+
+			multiSink.sendErrorEvent({ eventName: "errorEvent" });
+
+			assert.strictEqual(recordedA[0]?.logLevel, LogLevel.essential);
+			assert.strictEqual(recordedB[0]?.logLevel, LogLevel.essential);
+		});
+
+		for (const explicitLevel of [LogLevel.verbose, LogLevel.info] as const) {
+			it(`Forwards explicit logLevel (${explicitLevel}) unchanged through MultiSink to every sink via sendTelemetryEvent`, () => {
+				const { sink: sinkA, recorded: recordedA } = createRecordingSink(LogLevel.verbose);
+				const { sink: sinkB, recorded: recordedB } = createRecordingSink(LogLevel.verbose);
+				const multiSink = createMultiSinkLogger({ loggers: [sinkA, sinkB] });
+
+				multiSink.sendTelemetryEvent({ eventName: "explicit" }, undefined, explicitLevel);
+
+				assert.strictEqual(recordedA[0]?.logLevel, explicitLevel);
+				assert.strictEqual(recordedB[0]?.logLevel, explicitLevel);
+			});
+
+			it(`Forwards explicit logLevel (${explicitLevel}) unchanged through MultiSink via sendPerformanceEvent`, () => {
+				const { sink: sinkA, recorded: recordedA } = createRecordingSink(LogLevel.verbose);
+				const { sink: sinkB, recorded: recordedB } = createRecordingSink(LogLevel.verbose);
+				const multiSink = createMultiSinkLogger({ loggers: [sinkA, sinkB] });
+
+				multiSink.sendPerformanceEvent(
+					{ eventName: "explicitPerf" },
+					undefined,
+					explicitLevel,
+				);
+
+				assert.strictEqual(recordedA[0]?.logLevel, explicitLevel);
+				assert.strictEqual(recordedB[0]?.logLevel, explicitLevel);
+			});
+		}
+
+		it("Forwards LogLevel.essential through Child -> MultiSink -> sinks (no explicit logLevel)", () => {
+			const { sink: sinkA, recorded: recordedA } = createRecordingSink();
+			const { sink: sinkB, recorded: recordedB } = createRecordingSink();
+			const multiSink = createMultiSinkLogger({ loggers: [sinkA, sinkB] });
+			const child = createChildLogger({ logger: multiSink });
+
+			child.sendTelemetryEvent({ eventName: "chainDefault" });
+
+			assert.strictEqual(recordedA[0]?.logLevel, LogLevel.essential);
+			assert.strictEqual(recordedB[0]?.logLevel, LogLevel.essential);
+		});
+
+		it("Forwards explicit LogLevel.info through Child -> MultiSink -> sinks", () => {
+			const { sink: sinkA, recorded: recordedA } = createRecordingSink(LogLevel.verbose);
+			const { sink: sinkB, recorded: recordedB } = createRecordingSink(LogLevel.verbose);
+			const multiSink = createMultiSinkLogger({ loggers: [sinkA, sinkB] });
+			const child = createChildLogger({ logger: multiSink });
+
+			child.sendTelemetryEvent({ eventName: "chainExplicit" }, undefined, LogLevel.info);
+
+			assert.strictEqual(recordedA[0]?.logLevel, LogLevel.info);
+			assert.strictEqual(recordedB[0]?.logLevel, LogLevel.info);
+		});
+
+		it("Forwards explicit logLevel through MultiSink -> [Child(sinkA), sinkB]", () => {
+			const { sink: sinkA, recorded: recordedA } = createRecordingSink(LogLevel.verbose);
+			const { sink: sinkB, recorded: recordedB } = createRecordingSink(LogLevel.verbose);
+			const multiSink = createMultiSinkLogger({
+				loggers: [createChildLogger({ logger: sinkA }), sinkB],
+			});
+
+			multiSink.sendTelemetryEvent({ eventName: "mixedChain" }, undefined, LogLevel.verbose);
+
+			assert.strictEqual(recordedA[0]?.logLevel, LogLevel.verbose);
+			assert.strictEqual(recordedB[0]?.logLevel, LogLevel.verbose);
+		});
+
+		it("Regression: MultiSinkLogger.send forwards explicit logLevel to every sink (was previously dropped)", () => {
+			const { sink: sinkA, recorded: recordedA } = createRecordingSink(LogLevel.verbose);
+			const { sink: sinkB, recorded: recordedB } = createRecordingSink(LogLevel.verbose);
+			const multiSink = createMultiSinkLogger({
+				loggers: [sinkA, sinkB],
+			}) as MultiSinkLogger;
+
+			multiSink.send({ category: "generic", eventName: "directSend" }, LogLevel.verbose);
+
+			assert.strictEqual(recordedA[0]?.logLevel, LogLevel.verbose);
+			assert.strictEqual(recordedB[0]?.logLevel, LogLevel.verbose);
+		});
+	});
 });
diff --git a/packages/utils/telemetry-utils/src/test/utils.spec.ts b/packages/utils/telemetry-utils/src/test/utils.spec.ts
index a6498e693174..26833904973f 100644
--- a/packages/utils/telemetry-utils/src/test/utils.spec.ts
+++ b/packages/utils/telemetry-utils/src/test/utils.spec.ts
@@ -5,10 +5,11 @@
 
 import { strict as assert } from "node:assert";
 
-import type {
-	ConfigTypes,
-	IConfigProviderBase,
-	ITelemetryBaseEvent,
+import {
+	type ConfigTypes,
+	type IConfigProviderBase,
+	type ITelemetryBaseEvent,
+	LogLevel,
 } from "@fluidframework/core-interfaces";
 import type { InternalCoreInterfacesUtilityTypes } from "@fluidframework/core-interfaces/internal";
 
@@ -360,6 +361,75 @@ describe("Sampling", () => {
 			);
 		}
 	});
+
+	describe("logLevel forwarding", () => {
+		function createCapturingLogger(): {
+			logger: TelemetryLoggerExt;
+			captures: { method: string; logLevel: LogLevel | undefined }[];
+		} {
+			const captures: { method: string; logLevel: LogLevel | undefined }[] = [];
+			const logger: TelemetryLoggerExt = {
+				send: (_event, logLevel): void => {
+					captures.push({ method: "send", logLevel });
+				},
+				sendTelemetryEvent: (_event, _error, logLevel): void => {
+					captures.push({ method: "sendTelemetryEvent", logLevel });
+				},
+				sendErrorEvent: (_event, _error): void => {
+					captures.push({ method: "sendErrorEvent", logLevel: undefined });
+				},
+				sendPerformanceEvent: (_event, _error, logLevel): void => {
+					captures.push({ method: "sendPerformanceEvent", logLevel });
+				},
+			};
+			const wrapped = mixinMonitoringContext(logger, {
+				getRawConfig: (): ConfigTypes => undefined,
+			}).logger;
+			return { logger: wrapped, captures };
+		}
+
+		it("Forwards explicit logLevel through sendTelemetryEvent to the wrapped logger", () => {
+			const { logger, captures } = createCapturingLogger();
+			const sampled = createSampledLogger(logger);
+
+			sampled.sendTelemetryEvent({ eventName: "x" }, undefined, LogLevel.verbose);
+
+			assert.deepStrictEqual(captures, [
+				{ method: "sendTelemetryEvent", logLevel: LogLevel.verbose },
+			]);
+		});
+
+		it("Forwards explicit logLevel through sendPerformanceEvent to the wrapped logger", () => {
+			const { logger, captures } = createCapturingLogger();
+			const sampled = createSampledLogger(logger);
+
+			sampled.sendPerformanceEvent({ eventName: "x" }, undefined, LogLevel.info);
+
+			assert.deepStrictEqual(captures, [
+				{ method: "sendPerformanceEvent", logLevel: LogLevel.info },
+			]);
+		});
+
+		it("Forwards explicit logLevel through send to the wrapped logger", () => {
+			const { logger, captures } = createCapturingLogger();
+			const sampled = createSampledLogger(logger);
+
+			sampled.send({ category: "generic", eventName: "x" }, LogLevel.verbose);
+
+			assert.deepStrictEqual(captures, [{ method: "send", logLevel: LogLevel.verbose }]);
+		});
+
+		it("Forwards undefined logLevel when caller omits it", () => {
+			const { logger, captures } = createCapturingLogger();
+			const sampled = createSampledLogger(logger);
+
+			sampled.sendTelemetryEvent({ eventName: "x" });
+
+			assert.deepStrictEqual(captures, [
+				{ method: "sendTelemetryEvent", logLevel: undefined },
+			]);
+		});
+	});
 });
 
 describe("tagCodeArtifacts", () => {
diff --git a/packages/utils/telemetry-utils/src/utils.ts b/packages/utils/telemetry-utils/src/utils.ts
index 7f9c8a188846..3dfb49540d04 100644
--- a/packages/utils/telemetry-utils/src/utils.ts
+++ b/packages/utils/telemetry-utils/src/utils.ts
@@ -3,7 +3,7 @@
  * Licensed under the MIT License.
  */
 
-import type { ITelemetryBaseEvent } from "@fluidframework/core-interfaces";
+import type { ITelemetryBaseEvent, LogLevel } from "@fluidframework/core-interfaces";
 
 import { loggerToMonitoringContext } from "./config.js";
 import type {
@@ -66,7 +66,7 @@ export function createSampledLogger(
 		monitoringContext.config.getBoolean("Fluid.Telemetry.DisableSampling") ?? false;
 
 	const sampledLogger = {
-		send: (event: ITelemetryBaseEvent): void => {
+		send: (event: ITelemetryBaseEvent, logLevel?: LogLevel): void => {
 			// The sampler uses the following logic for sending events:
 			// 1. If isSamplingDisabled is true, then this means events should be unsampled. Therefore we send the event without any checks.
 			// 2. If isSamplingDisabled is false, then event should be sampled using the event sampler, if the sampler is not defined just send all events, other use the eventSampler.sample() method.
@@ -75,31 +75,39 @@ export function createSampledLogger(
 				if (isSamplingDisabled && (skipLoggingWhenSamplingIsDisabled ?? false)) {
 					return;
 				}
-				logger.send(event);
+				logger.send(event, logLevel);
 			}
 		},
-		sendTelemetryEvent: (event: ITelemetryGenericEventExt): void => {
+		sendTelemetryEvent: (
+			event: ITelemetryGenericEventExt,
+			error?: unknown,
+			logLevel?: typeof LogLevel.verbose | typeof LogLevel.info,
+		): void => {
 			if (isSamplingDisabled || eventSampler === undefined || eventSampler.sample()) {
 				if (isSamplingDisabled && (skipLoggingWhenSamplingIsDisabled ?? false)) {
 					return;
 				}
-				logger.sendTelemetryEvent(event);
+				logger.sendTelemetryEvent(event, error, logLevel);
 			}
 		},
-		sendErrorEvent: (event: ITelemetryGenericEventExt): void => {
+		sendErrorEvent: (event: ITelemetryGenericEventExt, error?: unknown): void => {
 			if (isSamplingDisabled || eventSampler === undefined || eventSampler.sample()) {
 				if (isSamplingDisabled && (skipLoggingWhenSamplingIsDisabled ?? false)) {
 					return;
 				}
-				logger.sendErrorEvent(event);
+				logger.sendErrorEvent(event, error);
 			}
 		},
-		sendPerformanceEvent: (event: ITelemetryGenericEventExt): void => {
+		sendPerformanceEvent: (
+			event: ITelemetryGenericEventExt,
+			error?: unknown,
+			logLevel?: typeof LogLevel.verbose | typeof LogLevel.info,
+		): void => {
 			if (isSamplingDisabled || eventSampler === undefined || eventSampler.sample()) {
 				if (isSamplingDisabled && (skipLoggingWhenSamplingIsDisabled ?? false)) {
 					return;
 				}
-				logger.sendPerformanceEvent(event);
+				logger.sendPerformanceEvent(event, error, logLevel);
 			}
 		},
 		isSamplingDisabled,

From 71c1f07a0aca8d8b8faf13f40379f932db60c2ec Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Wed, 6 May 2026 18:28:17 +0000
Subject: [PATCH 13/21] fix: removed type import from normal import

---
 .../telemetry-utils/src/test/multiSinkLogger.spec.ts   |  8 ++++----
 packages/utils/telemetry-utils/src/test/utils.spec.ts  | 10 +++++-----
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/packages/utils/telemetry-utils/src/test/multiSinkLogger.spec.ts b/packages/utils/telemetry-utils/src/test/multiSinkLogger.spec.ts
index 11ed26bd2c8e..2b3bb915bc53 100644
--- a/packages/utils/telemetry-utils/src/test/multiSinkLogger.spec.ts
+++ b/packages/utils/telemetry-utils/src/test/multiSinkLogger.spec.ts
@@ -5,11 +5,11 @@
 
 import { strict as assert } from "node:assert";
 
-import {
-	type ITelemetryBaseEvent,
-	type ITelemetryBaseLogger,
-	LogLevel,
+import type {
+	ITelemetryBaseEvent,
+	ITelemetryBaseLogger,
 } from "@fluidframework/core-interfaces";
+import { LogLevel } from "@fluidframework/core-interfaces";
 
 import { type MultiSinkLogger, createChildLogger, createMultiSinkLogger } from "../logger.js";
 import { MockLogger } from "../mockLogger.js";
diff --git a/packages/utils/telemetry-utils/src/test/utils.spec.ts b/packages/utils/telemetry-utils/src/test/utils.spec.ts
index 26833904973f..1c718d4c77ef 100644
--- a/packages/utils/telemetry-utils/src/test/utils.spec.ts
+++ b/packages/utils/telemetry-utils/src/test/utils.spec.ts
@@ -5,12 +5,12 @@
 
 import { strict as assert } from "node:assert";
 
-import {
-	type ConfigTypes,
-	type IConfigProviderBase,
-	type ITelemetryBaseEvent,
-	LogLevel,
+import type {
+	ConfigTypes,
+	IConfigProviderBase,
+	ITelemetryBaseEvent,
 } from "@fluidframework/core-interfaces";
+import { LogLevel } from "@fluidframework/core-interfaces";
 import type { InternalCoreInterfacesUtilityTypes } from "@fluidframework/core-interfaces/internal";
 
 import type { ITelemetryLoggerExt as ITelemetryLoggerExtInternal } from "@fluidframework/telemetry-utils/internal";

From 2c1318114b5f57126c66a17082053986982f1dbe Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Wed, 6 May 2026 21:53:03 +0000
Subject: [PATCH 14/21] fix: applied changes based on review

---
 .bash_profile                                 |  0
 .bashrc                                       |  0
 .claude/agents                                |  0
 .claude/commands                              |  0
 .gitconfig                                    |  0
 .idea                                         |  0
 .mcp.json                                     |  0
 .profile                                      |  0
 .ripgreprc                                    |  0
 .zprofile                                     |  0
 .zshrc                                        |  0
 packages/common/core-interfaces/src/logger.ts |  2 +-
 packages/utils/telemetry-utils/src/logger.ts  | 29 +++++-------
 .../utils/telemetry-utils/src/mockLogger.ts   |  2 +-
 .../src/test/childLogger.spec.ts              | 47 ++++++++++++++++---
 .../src/test/multiSinkLogger.spec.ts          | 38 +++------------
 .../telemetry-utils/src/test/utils.spec.ts    |  6 +--
 17 files changed, 62 insertions(+), 62 deletions(-)
 create mode 100644 .bash_profile
 create mode 100644 .bashrc
 create mode 100644 .claude/agents
 create mode 100644 .claude/commands
 create mode 100644 .gitconfig
 create mode 100644 .idea
 create mode 100644 .mcp.json
 create mode 100644 .profile
 create mode 100644 .ripgreprc
 create mode 100644 .zprofile
 create mode 100644 .zshrc

diff --git a/.bash_profile b/.bash_profile
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/.bashrc b/.bashrc
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/.claude/agents b/.claude/agents
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/.claude/commands b/.claude/commands
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/.gitconfig b/.gitconfig
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/.idea b/.idea
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/.mcp.json b/.mcp.json
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/.profile b/.profile
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/.ripgreprc b/.ripgreprc
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/.zprofile b/.zprofile
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/.zshrc b/.zshrc
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/packages/common/core-interfaces/src/logger.ts b/packages/common/core-interfaces/src/logger.ts
index aafe1e4a4f2e..8c34de839a4a 100644
--- a/packages/common/core-interfaces/src/logger.ts
+++ b/packages/common/core-interfaces/src/logger.ts
@@ -122,7 +122,7 @@ export interface ITelemetryBaseLogger {
 	/**
 	 * Log a telemetry event, if it meets the appropriate log-level threshold (see {@link ITelemetryBaseLogger.minLogLevel}).
 	 * @param event - The event to log.
-	 * @param logLevel - The log level of the event. If undefined, the event will be sent with {@link LogLevelConst.essential | LogLevel.essential}.
+	 * @param logLevel - The log level of the event. If undefined, the logLevel should be treated as {@link LogLevelConst.essential | LogLevel.essential}.
 	 */
 	send(event: ITelemetryBaseEvent, logLevel?: LogLevel): void;
 
diff --git a/packages/utils/telemetry-utils/src/logger.ts b/packages/utils/telemetry-utils/src/logger.ts
index 5f77f39c0895..7b04b738dada 100644
--- a/packages/utils/telemetry-utils/src/logger.ts
+++ b/packages/utils/telemetry-utils/src/logger.ts
@@ -217,7 +217,7 @@ export abstract class TelemetryLogger implements TelemetryLoggerExt {
 	 *
 	 * @param event - the event to send
 	 */
-	public abstract send(event: ITelemetryBaseEvent, logLevel: LogLevel): void;
+	public abstract send(event: ITelemetryBaseEvent, logLevel?: LogLevel): void;
 
 	/**
 	 * Send a telemetry event with the logger
@@ -230,15 +230,12 @@ export abstract class TelemetryLogger implements TelemetryLoggerExt {
 	public sendTelemetryEvent(
 		event: ITelemetryGenericEventExt,
 		error?: unknown,
-		logLevel:
-			| typeof LogLevel.verbose
-			| typeof LogLevel.info
-			| typeof LogLevel.essential = LogLevel.essential,
+		logLevel?: typeof LogLevel.verbose | typeof LogLevel.info,
 	): void {
 		this.sendTelemetryEventCore(
 			{ ...event, category: event.category ?? "generic" },
 			error,
-			event.category === "error" ? LogLevel.essential : logLevel,
+			event.category === "error" ? LogLevel.essential : (logLevel ?? LogLevel.essential),
 		);
 	}
 
@@ -298,10 +295,7 @@ export abstract class TelemetryLogger implements TelemetryLoggerExt {
 	public sendPerformanceEvent(
 		event: ITelemetryPerformanceEventExt,
 		error?: unknown,
-		logLevel:
-			| typeof LogLevel.verbose
-			| typeof LogLevel.info
-			| typeof LogLevel.essential = LogLevel.essential,
+		logLevel?: typeof LogLevel.verbose | typeof LogLevel.info,
 	): void {
 		const perfEvent = {
 			...event,
@@ -311,7 +305,7 @@ export abstract class TelemetryLogger implements TelemetryLoggerExt {
 		this.sendTelemetryEventCore(
 			perfEvent,
 			error,
-			perfEvent.category === "error" ? LogLevel.essential : logLevel,
+			perfEvent.category === "error" ? LogLevel.essential : (logLevel ?? LogLevel.essential),
 		);
 	}
 
@@ -523,9 +517,8 @@ export class ChildLogger extends TelemetryLogger {
 		return this.baseLogger.minLogLevel;
 	}
 
-	private shouldFilterOutEvent(event: ITelemetryBaseEvent, logLevel: LogLevel): boolean {
-		// Determine the log level of the event. The log level is now required, so it will always be provided.
-		const eventLogLevel = logLevel;
+	private shouldFilterOutEvent(event: ITelemetryBaseEvent, logLevel?: LogLevel): boolean {
+		const eventLogLevel = logLevel ?? LogLevel.essential;
 		const configLogLevel = this.baseLogger.minLogLevel ?? LogLevel.info;
 		// Filter out in case event log level is below what is wanted in config.
 		return eventLogLevel < configLogLevel;
@@ -536,11 +529,11 @@ export class ChildLogger extends TelemetryLogger {
 	 *
 	 * @param event - the event to send
 	 */
-	public send(event: ITelemetryBaseEvent, logLevel: LogLevel): void {
+	public send(event: ITelemetryBaseEvent, logLevel?: LogLevel): void {
 		if (this.shouldFilterOutEvent(event, logLevel)) {
 			return;
 		}
-		this.baseLogger.send(this.prepareEvent(event), logLevel);
+		this.baseLogger.send(this.prepareEvent(event), logLevel ?? LogLevel.essential);
 	}
 }
 
@@ -660,10 +653,10 @@ export class MultiSinkLogger extends TelemetryLogger {
 	 *
 	 * @param event - the event to send to all the registered logger
 	 */
-	public send(event: ITelemetryBaseEvent, logLevel: LogLevel): void {
+	public send(event: ITelemetryBaseEvent, logLevel?: LogLevel): void {
 		const newEvent = this.prepareEvent(event);
 		for (const logger of this.loggers) {
-			logger.send(newEvent, logLevel);
+			logger.send(newEvent, logLevel ?? LogLevel.essential);
 		}
 	}
 }
diff --git a/packages/utils/telemetry-utils/src/mockLogger.ts b/packages/utils/telemetry-utils/src/mockLogger.ts
index a413c9e1b2d0..2df2dea3df27 100644
--- a/packages/utils/telemetry-utils/src/mockLogger.ts
+++ b/packages/utils/telemetry-utils/src/mockLogger.ts
@@ -59,7 +59,7 @@ export class MockLogger implements ITelemetryBaseLogger {
 	 * {@inheritDoc @fluidframework/core-interfaces#ITelemetryBaseLogger.send}
 	 */
 	public send(event: ITelemetryBaseEvent, logLevel?: LogLevel): void {
-		if ((logLevel ?? LogLevel.info) >= this.minLogLevel) {
+		if ((logLevel ?? LogLevel.essential) >= this.minLogLevel) {
 			this._events.push(event);
 		}
 	}
diff --git a/packages/utils/telemetry-utils/src/test/childLogger.spec.ts b/packages/utils/telemetry-utils/src/test/childLogger.spec.ts
index 19a5e3fb932f..6269e5130486 100644
--- a/packages/utils/telemetry-utils/src/test/childLogger.spec.ts
+++ b/packages/utils/telemetry-utils/src/test/childLogger.spec.ts
@@ -199,15 +199,15 @@ describe("ChildLogger", () => {
 		const childLogger1 = createChildLogger({ logger });
 
 		childLogger1.send({ category: "error", eventName: "testEvent" }, LogLevel.essential);
-		assert(sent, "event should be sent");
+		assert(sent, "essential event should be sent");
 
 		sent = false;
 		childLogger1.send({ category: "generic", eventName: "testEvent" }, LogLevel.info);
-		assert(!sent, "event should not be sent");
+		assert(!sent, "info event should not be sent");
 
 		sent = false;
 		childLogger1.send({ category: "generic", eventName: "testEvent" });
-		assert(sent, "default event should be sent");
+		assert(sent, "event with undefined logLevel should be sent");
 	});
 
 	it("should receive verbose events with min loglevel set as verbose", () => {
@@ -225,11 +225,11 @@ describe("ChildLogger", () => {
 		const childLogger1 = createChildLogger({ logger });
 
 		childLogger1.send({ category: "generic", eventName: "testEvent" }, LogLevel.verbose);
-		assert(sent, "event should be sent");
+		assert(sent, "verbose event should be sent");
 
 		sent = false;
 		childLogger1.send({ category: "error", eventName: "testEvent" });
-		assert(sent, "default event should be sent");
+		assert(sent, "event with undefined logLevel should be sent");
 	});
 
 	it("should not receive verbose events with no min loglevel", () => {
@@ -245,7 +245,7 @@ describe("ChildLogger", () => {
 		const childLogger1 = createChildLogger({ logger });
 
 		childLogger1.send({ category: "error", eventName: "testEvent" });
-		assert(sent, "default event should be sent");
+		assert(sent, "event with undefined logLevel should be sent");
 
 		sent = false;
 		childLogger1.send({ category: "generic", eventName: "testEvent" }, LogLevel.verbose);
@@ -274,6 +274,39 @@ describe("ChildLogger", () => {
 		assert(!sent, "verbose event should not be sent");
 
 		childLogger1.send({ category: "generic", eventName: "testEvent" }, LogLevel.info);
-		assert(sent, "default event should be sent");
+		assert(sent, "info event should be sent");
+	});
+
+	describe("logLevel forwarding", () => {
+		function createRecordingSink(): {
+			sink: ITelemetryBaseLogger;
+			recorded: { event: ITelemetryBaseEvent; logLevel: LogLevel | undefined }[];
+		} {
+			const recorded: { event: ITelemetryBaseEvent; logLevel: LogLevel | undefined }[] = [];
+			const sink: ITelemetryBaseLogger = {
+				send: (event, logLevel): void => {
+					recorded.push({ event, logLevel });
+				},
+			};
+			return { sink, recorded };
+		}
+
+		it("Forwards LogLevel.essential to the sink when `sendTelemetryEvent` omits logLevel", () => {
+			const { sink, recorded } = createRecordingSink();
+			const child = createChildLogger({ logger: sink });
+
+			child.sendTelemetryEvent({ eventName: "chainDefault" });
+
+			assert.strictEqual(recorded[0]?.logLevel, LogLevel.essential);
+		});
+
+		it("Forwards explicit LogLevel.info to the sink via `sendTelemetryEvent`", () => {
+			const { sink, recorded } = createRecordingSink();
+			const child = createChildLogger({ logger: sink });
+
+			child.sendTelemetryEvent({ eventName: "chainExplicit" }, undefined, LogLevel.info);
+
+			assert.strictEqual(recorded[0]?.logLevel, LogLevel.info);
+		});
 	});
 });
diff --git a/packages/utils/telemetry-utils/src/test/multiSinkLogger.spec.ts b/packages/utils/telemetry-utils/src/test/multiSinkLogger.spec.ts
index 2b3bb915bc53..12a951a33343 100644
--- a/packages/utils/telemetry-utils/src/test/multiSinkLogger.spec.ts
+++ b/packages/utils/telemetry-utils/src/test/multiSinkLogger.spec.ts
@@ -150,20 +150,18 @@ describe("MultiSinkLogger", () => {
 	});
 
 	describe("logLevel propagation", () => {
-		it("Forwards LogLevel.essential to every sink when sendTelemetryEvent omits logLevel", () => {
+		it("Forwards LogLevel.essential to every sink when `sendTelemetryEvent` omits logLevel", () => {
 			const { sink: sinkA, recorded: recordedA } = createRecordingSink();
 			const { sink: sinkB, recorded: recordedB } = createRecordingSink();
 			const multiSink = createMultiSinkLogger({ loggers: [sinkA, sinkB] });
 
 			multiSink.sendTelemetryEvent({ eventName: "noLogLevel" });
 
-			assert.strictEqual(recordedA.length, 1);
-			assert.strictEqual(recordedB.length, 1);
 			assert.strictEqual(recordedA[0]?.logLevel, LogLevel.essential);
 			assert.strictEqual(recordedB[0]?.logLevel, LogLevel.essential);
 		});
 
-		it("Forwards LogLevel.essential to every sink when sendPerformanceEvent omits logLevel", () => {
+		it("Forwards LogLevel.essential to every sink when `sendPerformanceEvent` omits logLevel", () => {
 			const { sink: sinkA, recorded: recordedA } = createRecordingSink();
 			const { sink: sinkB, recorded: recordedB } = createRecordingSink();
 			const multiSink = createMultiSinkLogger({ loggers: [sinkA, sinkB] });
@@ -174,7 +172,7 @@ describe("MultiSinkLogger", () => {
 			assert.strictEqual(recordedB[0]?.logLevel, LogLevel.essential);
 		});
 
-		it("Forwards LogLevel.essential to every sink for sendErrorEvent", () => {
+		it("Forwards LogLevel.essential to every sink for `sendErrorEvent`", () => {
 			const { sink: sinkA, recorded: recordedA } = createRecordingSink();
 			const { sink: sinkB, recorded: recordedB } = createRecordingSink();
 			const multiSink = createMultiSinkLogger({ loggers: [sinkA, sinkB] });
@@ -186,7 +184,7 @@ describe("MultiSinkLogger", () => {
 		});
 
 		for (const explicitLevel of [LogLevel.verbose, LogLevel.info] as const) {
-			it(`Forwards explicit logLevel (${explicitLevel}) unchanged through MultiSink to every sink via sendTelemetryEvent`, () => {
+			it(`Forwards explicit logLevel (${explicitLevel}) unchanged through MultiSink to every sink via \`sendTelemetryEvent\``, () => {
 				const { sink: sinkA, recorded: recordedA } = createRecordingSink(LogLevel.verbose);
 				const { sink: sinkB, recorded: recordedB } = createRecordingSink(LogLevel.verbose);
 				const multiSink = createMultiSinkLogger({ loggers: [sinkA, sinkB] });
@@ -197,7 +195,7 @@ describe("MultiSinkLogger", () => {
 				assert.strictEqual(recordedB[0]?.logLevel, explicitLevel);
 			});
 
-			it(`Forwards explicit logLevel (${explicitLevel}) unchanged through MultiSink via sendPerformanceEvent`, () => {
+			it(`Forwards explicit logLevel (${explicitLevel}) unchanged through MultiSink via \`sendPerformanceEvent\``, () => {
 				const { sink: sinkA, recorded: recordedA } = createRecordingSink(LogLevel.verbose);
 				const { sink: sinkB, recorded: recordedB } = createRecordingSink(LogLevel.verbose);
 				const multiSink = createMultiSinkLogger({ loggers: [sinkA, sinkB] });
@@ -213,30 +211,6 @@ describe("MultiSinkLogger", () => {
 			});
 		}
 
-		it("Forwards LogLevel.essential through Child -> MultiSink -> sinks (no explicit logLevel)", () => {
-			const { sink: sinkA, recorded: recordedA } = createRecordingSink();
-			const { sink: sinkB, recorded: recordedB } = createRecordingSink();
-			const multiSink = createMultiSinkLogger({ loggers: [sinkA, sinkB] });
-			const child = createChildLogger({ logger: multiSink });
-
-			child.sendTelemetryEvent({ eventName: "chainDefault" });
-
-			assert.strictEqual(recordedA[0]?.logLevel, LogLevel.essential);
-			assert.strictEqual(recordedB[0]?.logLevel, LogLevel.essential);
-		});
-
-		it("Forwards explicit LogLevel.info through Child -> MultiSink -> sinks", () => {
-			const { sink: sinkA, recorded: recordedA } = createRecordingSink(LogLevel.verbose);
-			const { sink: sinkB, recorded: recordedB } = createRecordingSink(LogLevel.verbose);
-			const multiSink = createMultiSinkLogger({ loggers: [sinkA, sinkB] });
-			const child = createChildLogger({ logger: multiSink });
-
-			child.sendTelemetryEvent({ eventName: "chainExplicit" }, undefined, LogLevel.info);
-
-			assert.strictEqual(recordedA[0]?.logLevel, LogLevel.info);
-			assert.strictEqual(recordedB[0]?.logLevel, LogLevel.info);
-		});
-
 		it("Forwards explicit logLevel through MultiSink -> [Child(sinkA), sinkB]", () => {
 			const { sink: sinkA, recorded: recordedA } = createRecordingSink(LogLevel.verbose);
 			const { sink: sinkB, recorded: recordedB } = createRecordingSink(LogLevel.verbose);
@@ -250,7 +224,7 @@ describe("MultiSinkLogger", () => {
 			assert.strictEqual(recordedB[0]?.logLevel, LogLevel.verbose);
 		});
 
-		it("Regression: MultiSinkLogger.send forwards explicit logLevel to every sink (was previously dropped)", () => {
+		it("Regression: `MultiSinkLogger.send` forwards explicit logLevel to every sink (was previously dropped)", () => {
 			const { sink: sinkA, recorded: recordedA } = createRecordingSink(LogLevel.verbose);
 			const { sink: sinkB, recorded: recordedB } = createRecordingSink(LogLevel.verbose);
 			const multiSink = createMultiSinkLogger({
diff --git a/packages/utils/telemetry-utils/src/test/utils.spec.ts b/packages/utils/telemetry-utils/src/test/utils.spec.ts
index 1c718d4c77ef..af1d3e3f43f9 100644
--- a/packages/utils/telemetry-utils/src/test/utils.spec.ts
+++ b/packages/utils/telemetry-utils/src/test/utils.spec.ts
@@ -388,7 +388,7 @@ describe("Sampling", () => {
 			return { logger: wrapped, captures };
 		}
 
-		it("Forwards explicit logLevel through sendTelemetryEvent to the wrapped logger", () => {
+		it("Forwards explicit logLevel through `sendTelemetryEvent` to the wrapped logger", () => {
 			const { logger, captures } = createCapturingLogger();
 			const sampled = createSampledLogger(logger);
 
@@ -399,7 +399,7 @@ describe("Sampling", () => {
 			]);
 		});
 
-		it("Forwards explicit logLevel through sendPerformanceEvent to the wrapped logger", () => {
+		it("Forwards explicit logLevel through `sendPerformanceEvent` to the wrapped logger", () => {
 			const { logger, captures } = createCapturingLogger();
 			const sampled = createSampledLogger(logger);
 
@@ -410,7 +410,7 @@ describe("Sampling", () => {
 			]);
 		});
 
-		it("Forwards explicit logLevel through send to the wrapped logger", () => {
+		it("Forwards explicit logLevel through `send` to the wrapped logger", () => {
 			const { logger, captures } = createCapturingLogger();
 			const sampled = createSampledLogger(logger);
 

From 3b3f5fe4ae1fa94889d97fe1ad0e0d23e292103e Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Wed, 6 May 2026 22:00:58 +0000
Subject: [PATCH 15/21] docs: updated docs

---
 packages/utils/telemetry-utils/src/telemetryTypes.ts | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/packages/utils/telemetry-utils/src/telemetryTypes.ts b/packages/utils/telemetry-utils/src/telemetryTypes.ts
index b9b0c6ca3ac3..886ddafc0199 100644
--- a/packages/utils/telemetry-utils/src/telemetryTypes.ts
+++ b/packages/utils/telemetry-utils/src/telemetryTypes.ts
@@ -136,7 +136,7 @@ export interface ITelemetryLoggerExt extends ITelemetryBaseLogger {
 	 * Send an information telemetry event.
 	 * @param event - Event to send.
 	 * @param error - Optional error object to log.
-	 * @param logLevel - Optional level of the log. Default: {@link @fluidframework/core-interfaces#LogLevel.essential}.
+	 * @param logLevel - Optional level of the log. If undefined, the event should be treated as {@link @fluidframework/core-interfaces#LogLevel.essential}.
 	 * @deprecated This method is being removed without a replacement.
 	 * @see {@link https://github.com/microsoft/FluidFramework/issues/26910 | Issue #26910} for details.
 	 */
@@ -159,7 +159,7 @@ export interface ITelemetryLoggerExt extends ITelemetryBaseLogger {
 	 * Send a performance telemetry event.
 	 * @param event - Event to send
 	 * @param error - Optional error object to log.
-	 * @param logLevel - Optional level of the log. Default: {@link @fluidframework/core-interfaces#LogLevel.essential}.
+	 * @param logLevel - Optional level of the log. If undefined, the event should be treated as {@link @fluidframework/core-interfaces#LogLevel.essential}.
 	 * @deprecated This method is being removed without a replacement.
 	 * @see {@link https://github.com/microsoft/FluidFramework/issues/26910 | Issue #26910} for details.
 	 */
@@ -183,7 +183,7 @@ export interface TelemetryLoggerExt extends ITelemetryBaseLogger {
 	 * Send an information telemetry event.
 	 * @param event - Event to send.
 	 * @param error - Optional error object to log.
-	 * @param logLevel - Optional level of the log. If undefined, the event will be sent with {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential}.
+	 * @param logLevel - Optional level of the log. If undefined, the event should be treated as {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential}.
 	 */
 	sendTelemetryEvent(
 		event: ITelemetryGenericEventExt,
@@ -202,7 +202,7 @@ export interface TelemetryLoggerExt extends ITelemetryBaseLogger {
 	 * Send a performance telemetry event.
 	 * @param event - Event to send
 	 * @param error - Optional error object to log.
-	 * @param logLevel - Optional level of the log. If undefined, the event will be sent with {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential}.
+	 * @param logLevel - Optional level of the log. If undefined, the event should be treated as {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential}.
 	 */
 	sendPerformanceEvent(
 		event: ITelemetryPerformanceEventExt,

From fbd560a7690f8bb9a24ff8ae92d676ddef9ac3e2 Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Wed, 6 May 2026 22:02:42 +0000
Subject: [PATCH 16/21] docs: removed changeset

---
 .changeset/soft-doors-trade.md | 20 --------------------
 1 file changed, 20 deletions(-)
 delete mode 100644 .changeset/soft-doors-trade.md

diff --git a/.changeset/soft-doors-trade.md b/.changeset/soft-doors-trade.md
deleted file mode 100644
index 9ce0479f8a40..000000000000
--- a/.changeset/soft-doors-trade.md
+++ /dev/null
@@ -1,20 +0,0 @@
----
-"@fluidframework/telemetry-utils": minor
-"__section": other
----
-
-All internal implementations of ITelemetryLoggerExt now tag events with no explicit logLevel as essential
-
-`@fluidframework/telemetry-utils` previously forwarded events with no explicit `logLevel` to the base logger as `undefined` (treated as `LogLevel.info` = `20`). It now forwards them as `LogLevel.essential` (= `30`). Specifically:
-
-- `ChildLogger.shouldFilterOutEvent` now falls back to `LogLevel.essential` when an event has no `logLevel` (previously fell back to `LogLevel.default` = `LogLevel.info` = `20`).
-- `ChildLogger.send` now forwards `LogLevel.essential` to the base logger when no `logLevel` is supplied, instead of forwarding `undefined`.
-- The implicit `= LogLevel.default` parameter defaults on `TelemetryLogger.sendTelemetryEvent` and `sendPerformanceEvent` were removed; callers that omit `logLevel` now propagate `undefined` through the chain, where `ChildLogger` applies the new `essential` fallback above.
-
-#### Impact for downstream consumers
-
-Internal Fluid events that previously arrived at the base logger with `logLevel = undefined` will now arrive tagged as `30` (`essential`). Hosts that filter telemetry by numeric level should not start dropping `logLevel = 20` events as "non-essential" unless **all** running Fluid versions include this change. Older versions still send those same critical events at level `20`, and dropping them would lose telemetry.
-
-#### Events already explicitly tagged as `LogLevel.info`
-
-Note that this change only affects events emitted with **no** explicit `logLevel`. A set of events that are already explicitly tagged with `LogLevel.info` (= `20`) was introduced in [PR #27126](https://github.com/microsoft/FluidFramework/pull/27126) and is unaffected by this change. Those events continue to be emitted at level `20` by design and are the intended target for hosts that want to drop non-essential telemetry once all running Fluid versions include both PR #27126 and this change.

From 5d5fcb165cba310b76329837423451144a507c78 Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Wed, 6 May 2026 22:05:23 +0000
Subject: [PATCH 17/21] docs: updated performance docs

---
 packages/utils/telemetry-utils/src/logger.ts | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/utils/telemetry-utils/src/logger.ts b/packages/utils/telemetry-utils/src/logger.ts
index 7b04b738dada..7028911c5c25 100644
--- a/packages/utils/telemetry-utils/src/logger.ts
+++ b/packages/utils/telemetry-utils/src/logger.ts
@@ -764,8 +764,7 @@ export class PerformanceEvent {
 	 * @param sampleThreshold - events with the same name and category will be sent to the logger
 	 * only when we hit this many executions of the task. If unspecified, all events will be sent.
 	 * @param logLevel - optional {@link LogLevel} for events emitted by this performance event.
-	 * If unspecified, the `logLevel` property is left unset and the effective default is determined by
-	 * the logger implementation.
+	 * If unspecified, {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential} will be used.
 	 * @returns The results of the executed task
 	 *
 	 * @remarks Note that if the "same" event (category + eventName) would be emitted by different

From bee89e10e851faf2be7ade3419ff3ea0519b41a3 Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Wed, 6 May 2026 22:12:17 +0000
Subject: [PATCH 18/21] chore: untrack dev-container bind-mounted files
 accidentally added

Removes 11 zero-byte files added by mistake in 2c1318114b. These are
bind-mounted from the dev container host (shell rc files, IDE config,
MCP config) and don't belong in the repo.
---
 .bash_profile    | 0
 .bashrc          | 0
 .claude/agents   | 0
 .claude/commands | 0
 .gitconfig       | 0
 .idea            | 0
 .mcp.json        | 0
 .profile         | 0
 .ripgreprc       | 0
 .zprofile        | 0
 .zshrc           | 0
 11 files changed, 0 insertions(+), 0 deletions(-)
 delete mode 100644 .bash_profile
 delete mode 100644 .bashrc
 delete mode 100644 .claude/agents
 delete mode 100644 .claude/commands
 delete mode 100644 .gitconfig
 delete mode 100644 .idea
 delete mode 100644 .mcp.json
 delete mode 100644 .profile
 delete mode 100644 .ripgreprc
 delete mode 100644 .zprofile
 delete mode 100644 .zshrc

diff --git a/.bash_profile b/.bash_profile
deleted file mode 100644
index e69de29bb2d1..000000000000
diff --git a/.bashrc b/.bashrc
deleted file mode 100644
index e69de29bb2d1..000000000000
diff --git a/.claude/agents b/.claude/agents
deleted file mode 100644
index e69de29bb2d1..000000000000
diff --git a/.claude/commands b/.claude/commands
deleted file mode 100644
index e69de29bb2d1..000000000000
diff --git a/.gitconfig b/.gitconfig
deleted file mode 100644
index e69de29bb2d1..000000000000
diff --git a/.idea b/.idea
deleted file mode 100644
index e69de29bb2d1..000000000000
diff --git a/.mcp.json b/.mcp.json
deleted file mode 100644
index e69de29bb2d1..000000000000
diff --git a/.profile b/.profile
deleted file mode 100644
index e69de29bb2d1..000000000000
diff --git a/.ripgreprc b/.ripgreprc
deleted file mode 100644
index e69de29bb2d1..000000000000
diff --git a/.zprofile b/.zprofile
deleted file mode 100644
index e69de29bb2d1..000000000000
diff --git a/.zshrc b/.zshrc
deleted file mode 100644
index e69de29bb2d1..000000000000

From 1131b6208569d53ce8ed377602bdc9ce1bc65b10 Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Wed, 6 May 2026 22:14:42 +0000
Subject: [PATCH 19/21] docs: updated docs message

---
 packages/utils/telemetry-utils/src/telemetryTypes.ts | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/packages/utils/telemetry-utils/src/telemetryTypes.ts b/packages/utils/telemetry-utils/src/telemetryTypes.ts
index 886ddafc0199..500c69176c54 100644
--- a/packages/utils/telemetry-utils/src/telemetryTypes.ts
+++ b/packages/utils/telemetry-utils/src/telemetryTypes.ts
@@ -136,7 +136,7 @@ export interface ITelemetryLoggerExt extends ITelemetryBaseLogger {
 	 * Send an information telemetry event.
 	 * @param event - Event to send.
 	 * @param error - Optional error object to log.
-	 * @param logLevel - Optional level of the log. If undefined, the event should be treated as {@link @fluidframework/core-interfaces#LogLevel.essential}.
+	 * @param logLevel - Optional level of the log. If undefined, the logLevel should be treated as {@link @fluidframework/core-interfaces#LogLevel.essential}.
 	 * @deprecated This method is being removed without a replacement.
 	 * @see {@link https://github.com/microsoft/FluidFramework/issues/26910 | Issue #26910} for details.
 	 */
@@ -159,7 +159,7 @@ export interface ITelemetryLoggerExt extends ITelemetryBaseLogger {
 	 * Send a performance telemetry event.
 	 * @param event - Event to send
 	 * @param error - Optional error object to log.
-	 * @param logLevel - Optional level of the log. If undefined, the event should be treated as {@link @fluidframework/core-interfaces#LogLevel.essential}.
+	 * @param logLevel - Optional level of the log. If undefined, the logLevel should be treated as {@link @fluidframework/core-interfaces#LogLevel.essential}.
 	 * @deprecated This method is being removed without a replacement.
 	 * @see {@link https://github.com/microsoft/FluidFramework/issues/26910 | Issue #26910} for details.
 	 */
@@ -183,7 +183,7 @@ export interface TelemetryLoggerExt extends ITelemetryBaseLogger {
 	 * Send an information telemetry event.
 	 * @param event - Event to send.
 	 * @param error - Optional error object to log.
-	 * @param logLevel - Optional level of the log. If undefined, the event should be treated as {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential}.
+	 * @param logLevel - Optional level of the log. If undefined, the logLevel should be treated as {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential}.
 	 */
 	sendTelemetryEvent(
 		event: ITelemetryGenericEventExt,
@@ -202,7 +202,7 @@ export interface TelemetryLoggerExt extends ITelemetryBaseLogger {
 	 * Send a performance telemetry event.
 	 * @param event - Event to send
 	 * @param error - Optional error object to log.
-	 * @param logLevel - Optional level of the log. If undefined, the event should be treated as {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential}.
+	 * @param logLevel - Optional level of the log. If undefined, the logLevel should be treated as {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential}.
 	 */
 	sendPerformanceEvent(
 		event: ITelemetryPerformanceEventExt,

From 1205a20df35f74221c0695c8563c0218339076b4 Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Thu, 7 May 2026 22:07:45 +0000
Subject: [PATCH 20/21] feat: applied changes based on comments

---
 .changeset/salty-colts-appear.md              | 10 ++--
 packages/utils/telemetry-utils/src/logger.ts  | 12 ++--
 .../telemetry-utils/src/telemetryTypes.ts     |  8 ++-
 .../src/test/childLogger.spec.ts              | 41 ++-----------
 .../src/test/telemetryLogger.spec.ts          | 57 ++++++++++++++++++-
 5 files changed, 78 insertions(+), 50 deletions(-)

diff --git a/.changeset/salty-colts-appear.md b/.changeset/salty-colts-appear.md
index 29047d214ebe..9abf1432cb57 100644
--- a/.changeset/salty-colts-appear.md
+++ b/.changeset/salty-colts-appear.md
@@ -5,11 +5,13 @@
 
 Deprecated LogLevel.default and LogLevel.error
 
-`LogLevel.default` and `LogLevel.error` in `@fluidframework/core-interfaces` are deprecated in favor of the semantically clearer `LogLevel.info` and `LogLevel.essential` respectively.
+`LogLevel.default` and `LogLevel.error` in `@fluidframework/core-interfaces` are deprecated in favor of the semantically clearer `LogLevel.info` and `LogLevel.essential`.
 
 #### Migration
 
-- `LogLevel.default` (= `20`) → use `LogLevel.info`
-- `LogLevel.error` (= `30`) → use `LogLevel.essential`
+The recommended replacement depends on how the value is used:
 
-Removal is tracked in [issue #26969](https://github.com/microsoft/FluidFramework/issues/26969) and is planned for the v3.0 major release.
+- For an **event's `logLevel`** (e.g. the `logLevel` argument to `sendTelemetryEvent` / `sendPerformanceEvent` / `ITelemetryBaseLogger.send`), the recommendation is `LogLevel.essential`.
+- For a logger's **`minLogLevel`** (the threshold that filters events), `LogLevel.info` is the recommendation.
+
+See [issue #26969](https://github.com/microsoft/FluidFramework/issues/26969) for full guidance and removal tracking (planned for v3.0).
diff --git a/packages/utils/telemetry-utils/src/logger.ts b/packages/utils/telemetry-utils/src/logger.ts
index 7028911c5c25..5abf73a0239f 100644
--- a/packages/utils/telemetry-utils/src/logger.ts
+++ b/packages/utils/telemetry-utils/src/logger.ts
@@ -224,8 +224,8 @@ export abstract class TelemetryLogger implements TelemetryLoggerExt {
 	 *
 	 * @param event - the event to send
 	 * @param error - optional error object to log
-	 * @param logLevel - optional level of the log. It category of event is set as error,
-	 * then the logLevel will be upgraded to be an error.
+	 * @param logLevel - optional level of the log. If the event's category is `error`,
+	 * the logLevel will be upgraded to {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential}.
 	 */
 	public sendTelemetryEvent(
 		event: ITelemetryGenericEventExt,
@@ -289,8 +289,8 @@ export abstract class TelemetryLogger implements TelemetryLoggerExt {
 	 *
 	 * @param event - Event to send
 	 * @param error - optional error object to log
-	 * @param logLevel - optional level of the log. It category of event is set as error,
-	 * then the logLevel will be upgraded to be an error.
+	 * @param logLevel - optional level of the log. If the event's category is `error`,
+	 * the logLevel will be upgraded to {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential}.
 	 */
 	public sendPerformanceEvent(
 		event: ITelemetryPerformanceEventExt,
@@ -805,12 +805,12 @@ export class PerformanceEvent {
 	private readonly startTime = performanceNow();
 	private startMark?: string;
 
-	protected constructor(
+	private constructor(
 		private readonly logger: TelemetryLoggerExt,
 		event: ITelemetryGenericEventExt,
 		private readonly markers: IPerformanceEventMarkers = { end: true, cancel: "generic" },
 		private readonly emitLogs: boolean = true,
-		private readonly logLevel?: typeof LogLevel.verbose | typeof LogLevel.info,
+		private readonly logLevel: typeof LogLevel.verbose | typeof LogLevel.info | undefined,
 	) {
 		this.event = { ...event };
 		if (this.markers.start) {
diff --git a/packages/utils/telemetry-utils/src/telemetryTypes.ts b/packages/utils/telemetry-utils/src/telemetryTypes.ts
index 500c69176c54..b444a4a64e44 100644
--- a/packages/utils/telemetry-utils/src/telemetryTypes.ts
+++ b/packages/utils/telemetry-utils/src/telemetryTypes.ts
@@ -137,6 +137,7 @@ export interface ITelemetryLoggerExt extends ITelemetryBaseLogger {
 	 * @param event - Event to send.
 	 * @param error - Optional error object to log.
 	 * @param logLevel - Optional level of the log. If undefined, the logLevel should be treated as {@link @fluidframework/core-interfaces#LogLevel.essential}.
+	 * If the event's category is `error`, the logLevel will be upgraded to {@link @fluidframework/core-interfaces#LogLevel.essential}.
 	 * @deprecated This method is being removed without a replacement.
 	 * @see {@link https://github.com/microsoft/FluidFramework/issues/26910 | Issue #26910} for details.
 	 */
@@ -160,6 +161,7 @@ export interface ITelemetryLoggerExt extends ITelemetryBaseLogger {
 	 * @param event - Event to send
 	 * @param error - Optional error object to log.
 	 * @param logLevel - Optional level of the log. If undefined, the logLevel should be treated as {@link @fluidframework/core-interfaces#LogLevel.essential}.
+	 * If the event's category is `error`, the logLevel will be upgraded to {@link @fluidframework/core-interfaces#LogLevel.essential}.
 	 * @deprecated This method is being removed without a replacement.
 	 * @see {@link https://github.com/microsoft/FluidFramework/issues/26910 | Issue #26910} for details.
 	 */
@@ -183,7 +185,8 @@ export interface TelemetryLoggerExt extends ITelemetryBaseLogger {
 	 * Send an information telemetry event.
 	 * @param event - Event to send.
 	 * @param error - Optional error object to log.
-	 * @param logLevel - Optional level of the log. If undefined, the logLevel should be treated as {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential}.
+	 * @param logLevel - Optional level of the log. If undefined, the logLevel will be treated as {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential}.
+	 * If the event's category is `error`, the logLevel will be upgraded to {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential}.
 	 */
 	sendTelemetryEvent(
 		event: ITelemetryGenericEventExt,
@@ -202,7 +205,8 @@ export interface TelemetryLoggerExt extends ITelemetryBaseLogger {
 	 * Send a performance telemetry event.
 	 * @param event - Event to send
 	 * @param error - Optional error object to log.
-	 * @param logLevel - Optional level of the log. If undefined, the logLevel should be treated as {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential}.
+	 * @param logLevel - Optional level of the log. If undefined, the logLevel will be treated as {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential}.
+	 * If the event's category is `error`, the logLevel will be upgraded to {@link @fluidframework/core-interfaces#LogLevelConst.essential | LogLevel.essential}.
 	 */
 	sendPerformanceEvent(
 		event: ITelemetryPerformanceEventExt,
diff --git a/packages/utils/telemetry-utils/src/test/childLogger.spec.ts b/packages/utils/telemetry-utils/src/test/childLogger.spec.ts
index 6269e5130486..9a713bc16e64 100644
--- a/packages/utils/telemetry-utils/src/test/childLogger.spec.ts
+++ b/packages/utils/telemetry-utils/src/test/childLogger.spec.ts
@@ -32,7 +32,7 @@ describe("ChildLogger", () => {
 			},
 		});
 
-		childLogger1.send({ category: "generic", eventName: "test1" }, LogLevel.essential);
+		childLogger1.send({ category: "generic", eventName: "test1" });
 		assert(sent, "event should be sent");
 
 		sent = false;
@@ -65,7 +65,7 @@ describe("ChildLogger", () => {
 			},
 		});
 
-		childLogger2.send({ category: "generic", eventName: "testEvent" }, LogLevel.essential);
+		childLogger2.send({ category: "generic", eventName: "testEvent" });
 		assert(sent, "event should be sent");
 	});
 
@@ -94,7 +94,7 @@ describe("ChildLogger", () => {
 			},
 		});
 
-		childLogger2.send({ category: "generic", eventName: "testEvent" }, LogLevel.essential);
+		childLogger2.send({ category: "generic", eventName: "testEvent" });
 		assert(sent, "event should be sent");
 	});
 
@@ -123,7 +123,7 @@ describe("ChildLogger", () => {
 			},
 		});
 
-		childLogger2.send({ category: "generic", eventName: "testEvent" }, LogLevel.essential);
+		childLogger2.send({ category: "generic", eventName: "testEvent" });
 		assert(sent, "event should be sent");
 	});
 
@@ -276,37 +276,4 @@ describe("ChildLogger", () => {
 		childLogger1.send({ category: "generic", eventName: "testEvent" }, LogLevel.info);
 		assert(sent, "info event should be sent");
 	});
-
-	describe("logLevel forwarding", () => {
-		function createRecordingSink(): {
-			sink: ITelemetryBaseLogger;
-			recorded: { event: ITelemetryBaseEvent; logLevel: LogLevel | undefined }[];
-		} {
-			const recorded: { event: ITelemetryBaseEvent; logLevel: LogLevel | undefined }[] = [];
-			const sink: ITelemetryBaseLogger = {
-				send: (event, logLevel): void => {
-					recorded.push({ event, logLevel });
-				},
-			};
-			return { sink, recorded };
-		}
-
-		it("Forwards LogLevel.essential to the sink when `sendTelemetryEvent` omits logLevel", () => {
-			const { sink, recorded } = createRecordingSink();
-			const child = createChildLogger({ logger: sink });
-
-			child.sendTelemetryEvent({ eventName: "chainDefault" });
-
-			assert.strictEqual(recorded[0]?.logLevel, LogLevel.essential);
-		});
-
-		it("Forwards explicit LogLevel.info to the sink via `sendTelemetryEvent`", () => {
-			const { sink, recorded } = createRecordingSink();
-			const child = createChildLogger({ logger: sink });
-
-			child.sendTelemetryEvent({ eventName: "chainExplicit" }, undefined, LogLevel.info);
-
-			assert.strictEqual(recorded[0]?.logLevel, LogLevel.info);
-		});
-	});
 });
diff --git a/packages/utils/telemetry-utils/src/test/telemetryLogger.spec.ts b/packages/utils/telemetry-utils/src/test/telemetryLogger.spec.ts
index 01041d727b26..584ff6a9c687 100644
--- a/packages/utils/telemetry-utils/src/test/telemetryLogger.spec.ts
+++ b/packages/utils/telemetry-utils/src/test/telemetryLogger.spec.ts
@@ -6,6 +6,7 @@
 import { strict as assert } from "node:assert";
 
 import type { ITelemetryBaseEvent, Tagged } from "@fluidframework/core-interfaces";
+import { LogLevel } from "@fluidframework/core-interfaces";
 
 import {
 	type ITelemetryLoggerPropertyBag,
@@ -17,8 +18,10 @@ import type { TelemetryEventPropertyTypeExt } from "../telemetryTypes.js";
 
 class TestTelemetryLogger extends TelemetryLogger {
 	public events: ITelemetryBaseEvent[] = [];
-	public send(event: ITelemetryBaseEvent): void {
+	public logLevels: (LogLevel | undefined)[] = [];
+	public send(event: ITelemetryBaseEvent, logLevel?: LogLevel): void {
 		this.events.push(this.prepareEvent(event));
+		this.logLevels.push(logLevel);
 	}
 }
 
@@ -197,6 +200,58 @@ describe("TelemetryLogger", () => {
 			}
 		});
 	});
+
+	describe("logLevel forwarding", () => {
+		it("`sendTelemetryEvent` without logLevel forwards LogLevel.essential", () => {
+			const logger = new TestTelemetryLogger();
+			logger.sendTelemetryEvent({ eventName: "noLevel" });
+			assert.deepStrictEqual(logger.logLevels, [LogLevel.essential]);
+		});
+
+		it("`sendTelemetryEvent` with explicit LogLevel.info forwards LogLevel.info", () => {
+			const logger = new TestTelemetryLogger();
+			logger.sendTelemetryEvent({ eventName: "infoLevel" }, undefined, LogLevel.info);
+			assert.deepStrictEqual(logger.logLevels, [LogLevel.info]);
+		});
+
+		it("`sendTelemetryEvent` with category 'error' forwards LogLevel.essential even when info is requested", () => {
+			const logger = new TestTelemetryLogger();
+			logger.sendTelemetryEvent(
+				{ eventName: "errorEvent", category: "error" },
+				undefined,
+				LogLevel.info,
+			);
+			assert.deepStrictEqual(logger.logLevels, [LogLevel.essential]);
+		});
+
+		it("`sendPerformanceEvent` without logLevel forwards LogLevel.essential", () => {
+			const logger = new TestTelemetryLogger();
+			logger.sendPerformanceEvent({ eventName: "perfNoLevel" });
+			assert.deepStrictEqual(logger.logLevels, [LogLevel.essential]);
+		});
+
+		it("`sendPerformanceEvent` with explicit LogLevel.info forwards LogLevel.info", () => {
+			const logger = new TestTelemetryLogger();
+			logger.sendPerformanceEvent({ eventName: "perfInfo" }, undefined, LogLevel.info);
+			assert.deepStrictEqual(logger.logLevels, [LogLevel.info]);
+		});
+
+		it("`sendPerformanceEvent` with category 'error' forwards LogLevel.essential even when info is requested", () => {
+			const logger = new TestTelemetryLogger();
+			logger.sendPerformanceEvent(
+				{ eventName: "perfError", category: "error" },
+				undefined,
+				LogLevel.info,
+			);
+			assert.deepStrictEqual(logger.logLevels, [LogLevel.essential]);
+		});
+
+		it("`sendErrorEvent` forwards LogLevel.essential", () => {
+			const logger = new TestTelemetryLogger();
+			logger.sendErrorEvent({ eventName: "errEvent" });
+			assert.deepStrictEqual(logger.logLevels, [LogLevel.essential]);
+		});
+	});
 });
 
 describe("convertToBasePropertyType", () => {

From 03adcc416d33ff085ba8e042faa42cdc6d4804e2 Mon Sep 17 00:00:00 2001
From: MarioJGMsoft <marioja@microsoft.com>
Date: Thu, 7 May 2026 23:12:56 +0000
Subject: [PATCH 21/21] feat: updated guidance and returned childLogger--Sink
 tests

---
 .changeset/salty-colts-appear.md              |  8 ++--
 .../src/test/childLogger.spec.ts              | 43 +++++++++++++++++++
 2 files changed, 48 insertions(+), 3 deletions(-)

diff --git a/.changeset/salty-colts-appear.md b/.changeset/salty-colts-appear.md
index 9abf1432cb57..92ac8510cb52 100644
--- a/.changeset/salty-colts-appear.md
+++ b/.changeset/salty-colts-appear.md
@@ -9,9 +9,11 @@ Deprecated LogLevel.default and LogLevel.error
 
 #### Migration
 
-The recommended replacement depends on how the value is used:
+The recommended replacement for `LogLevel.default` depends on how the value is used:
 
-- For an **event's `logLevel`** (e.g. the `logLevel` argument to `sendTelemetryEvent` / `sendPerformanceEvent` / `ITelemetryBaseLogger.send`), the recommendation is `LogLevel.essential`.
-- For a logger's **`minLogLevel`** (the threshold that filters events), `LogLevel.info` is the recommendation.
+- For an **event's default `logLevel`** (e.g. the `logLevel` argument to `sendTelemetryEvent` / `sendPerformanceEvent` / `ITelemetryBaseLogger.send`), the recommendation is `LogLevel.essential`.
+- For a logger's **default `minLogLevel`** (the threshold that filters events), `LogLevel.info` is the recommendation.
+
+The replacement for `LogLevel.error` should always be essential.
 
 See [issue #26969](https://github.com/microsoft/FluidFramework/issues/26969) for full guidance and removal tracking (planned for v3.0).
diff --git a/packages/utils/telemetry-utils/src/test/childLogger.spec.ts b/packages/utils/telemetry-utils/src/test/childLogger.spec.ts
index 9a713bc16e64..fda2a29d254b 100644
--- a/packages/utils/telemetry-utils/src/test/childLogger.spec.ts
+++ b/packages/utils/telemetry-utils/src/test/childLogger.spec.ts
@@ -277,3 +277,46 @@ describe("ChildLogger", () => {
 		assert(sent, "info event should be sent");
 	});
 });
+describe("logLevel forwarding", () => {
+	function createRecordingSink(minLogLevel?: LogLevel): {
+		sink: ITelemetryBaseLogger;
+		recorded: { event: ITelemetryBaseEvent; logLevel: LogLevel | undefined }[];
+	} {
+		const recorded: { event: ITelemetryBaseEvent; logLevel: LogLevel | undefined }[] = [];
+		const sink: ITelemetryBaseLogger = {
+			send: (event, logLevel): void => {
+				recorded.push({ event, logLevel });
+			},
+			minLogLevel,
+		};
+		return { sink, recorded };
+	}
+
+	it("Forwards LogLevel.essential to the sink when `sendTelemetryEvent` omits logLevel", () => {
+		const { sink, recorded } = createRecordingSink();
+		const child = createChildLogger({ logger: sink });
+
+		child.sendTelemetryEvent({ eventName: "chainDefault" });
+
+		assert.strictEqual(recorded[0]?.logLevel, LogLevel.essential);
+	});
+
+	it("Forwards explicit LogLevel.info to the sink via `sendTelemetryEvent`", () => {
+		const { sink, recorded } = createRecordingSink();
+		const child = createChildLogger({ logger: sink });
+
+		child.sendTelemetryEvent({ eventName: "chainExplicit" }, undefined, LogLevel.info);
+
+		assert.strictEqual(recorded[0]?.logLevel, LogLevel.info);
+	});
+
+	it("Forwards LogLevel.verbose to the sink via `sendTelemetryEvent`", () => {
+		// You have to add a minLogLevel of verbose to the sink to receive verbose events, otherwise they will be dropped.
+		const { sink, recorded } = createRecordingSink(LogLevel.verbose);
+		const child = createChildLogger({ logger: sink });
+
+		child.sendTelemetryEvent({ eventName: "chainDefault" }, undefined, LogLevel.verbose);
+
+		assert.strictEqual(recorded[0]?.logLevel, LogLevel.verbose);
+	});
+});