diff --git a/src/sdk/logger.test.ts b/src/sdk/logger.test.ts
index bf4951cf..75b645e9 100644
--- a/src/sdk/logger.test.ts
+++ b/src/sdk/logger.test.ts
@@ -36,7 +36,7 @@ describe("defaultLoggerAdapter", () => {
     expect(logSpy).toHaveBeenCalledOnce();
     const arg = logSpy.mock.calls[0]?.[0] as string;
     const parsed = JSON.parse(arg);
-    expect(parsed).toMatchObject({ level: "info", msg: "hello", foo: 1 });
+    expect(parsed).toMatchObject({ level: "INFO", msg: "hello", foo: 1 });
     expect(typeof parsed.timestamp).toBe("string");
   });
 
diff --git a/src/sdk/logger.ts b/src/sdk/logger.ts
index c9aab8a3..67b667e4 100644
--- a/src/sdk/logger.ts
+++ b/src/sdk/logger.ts
@@ -52,7 +52,7 @@ export interface LoggerAdapter {
 export const defaultLoggerAdapter: LoggerAdapter = {
   log(level, msg, attrs) {
     const payload: Record<string, unknown> = {
-      level,
+      level: level.toUpperCase(),
       msg,
       timestamp: new Date().toISOString(),
     };
diff --git a/src/sdk/otel.test.ts b/src/sdk/otel.test.ts
index fd847321..fd23215a 100644
--- a/src/sdk/otel.test.ts
+++ b/src/sdk/otel.test.ts
@@ -449,7 +449,7 @@ describe("instrumentWorker — OTLP/HTTP error-log channel wiring", () => {
       }>;
     };
     const rec = payload.resourceLogs[0].scopeLogs[0].logRecords[0];
-    expect(rec.severityText).toBe("error");
+    expect(rec.severityText).toBe("ERROR");
     expect(rec.body.stringValue).toBe("payment failed");
   });
 
@@ -498,7 +498,7 @@ describe("instrumentWorker — OTLP/HTTP error-log channel wiring", () => {
     const payload = JSON.parse(calls[0].body) as {
       resourceLogs: Array<{ scopeLogs: Array<{ logRecords: Array<{ severityText: string }> }> }>;
     };
-    expect(payload.resourceLogs[0].scopeLogs[0].logRecords[0].severityText).toBe("info");
+    expect(payload.resourceLogs[0].scopeLogs[0].logRecords[0].severityText).toBe("INFO");
   });
 
   it("otlpLogsEnabled=false disables the channel even when env is set", async () => {
diff --git a/src/sdk/otel.ts b/src/sdk/otel.ts
index c3e0e814..6d6e44de 100644
--- a/src/sdk/otel.ts
+++ b/src/sdk/otel.ts
@@ -754,7 +754,7 @@ function bootObservability(opts: OtelOptions, env: Record<string, unknown>): voi
         try {
           warnDirect(
             JSON.stringify({
-              level: "warn",
+              level: "WARN",
               msg: "otlp error-log exporter",
               kind,
               error: err instanceof Error ? err.message : String(err),
@@ -819,7 +819,7 @@ function bootObservability(opts: OtelOptions, env: Record<string, unknown>): voi
         try {
           warnDirect(
             JSON.stringify({
-              level: "warn",
+              level: "WARN",
               msg: "otlp metrics exporter",
               kind,
               error: err instanceof Error ? err.message : String(err),
@@ -891,7 +891,7 @@ function bootObservability(opts: OtelOptions, env: Record<string, unknown>): voi
         try {
           warnDirect(
             JSON.stringify({
-              level: "warn",
+              level: "WARN",
               msg: "otlp traces exporter",
               kind,
               error: err instanceof Error ? err.message : String(err),
@@ -928,7 +928,7 @@ function bootObservability(opts: OtelOptions, env: Record<string, unknown>): voi
   try {
     warnDirect(
       JSON.stringify({
-        level: "info",
+        level: "INFO",
         msg: "observability booted",
         service: serviceName,
         analyticsEngine: aeEnabled,
diff --git a/src/sdk/otelHttpLog.test.ts b/src/sdk/otelHttpLog.test.ts
index e5fc1214..0189d1c9 100644
--- a/src/sdk/otelHttpLog.test.ts
+++ b/src/sdk/otelHttpLog.test.ts
@@ -83,7 +83,7 @@ describe("createOtlpHttpLogAdapter — level filter + OTLP shape", () => {
     expect(calls).toHaveLength(1);
     const p = JSON.parse(String(calls[0].init.body)) as OtlpLogsPayload;
     const r = p.resourceLogs[0].scopeLogs[0].logRecords[0];
-    expect(r.severityText).toBe("error");
+    expect(r.severityText).toBe("ERROR");
     expect(r.severityNumber).toBe(17);
     expect(r.body.stringValue).toBe("boom");
     expect(r.attributes).toContainEqual({
diff --git a/src/sdk/otelHttpLog.ts b/src/sdk/otelHttpLog.ts
index 0f6b45b4..2269d370 100644
--- a/src/sdk/otelHttpLog.ts
+++ b/src/sdk/otelHttpLog.ts
@@ -217,7 +217,7 @@ export function createOtlpHttpLogAdapter(options: OtlpHttpLogOptions): OtlpHttpL
         timeUnixNano: t,
         observedTimeUnixNano: t,
         severityNumber: SEVERITY_NUMBER[level],
-        severityText: level,
+        severityText: level.toUpperCase(),
         body: msg,
         attributes: attrs ? { ...attrs } : {},
         traceId: spanCtx?.traceId ?? "",