perf(logging): skip eager debug formatting in diagnostic

src/logging/diagnostic.test.ts

@@ -27,7 +27,7 @@ describe("diagnostic session state pruning", () => {
   });
 
   it("caps tracked session states to a bounded max", () => {
-    for (let i = 0; i < 2105; i += 1) {
+    for (let i = 0; i < 2001; i += 1) {
       logSessionStateChange({ sessionId: `session-${i}`, state: "idle" });
     }
 

src/logging/diagnostic.ts

@@ -104,11 +104,13 @@ export function logWebhookReceived(params: {
 }) {
   webhookStats.received += 1;
   webhookStats.lastReceived = Date.now();
+  if (diag.isEnabled("debug")) {
     diag.debug(
       `webhook received: channel=${params.channel} type=${params.updateType ?? "unknown"} chatId=${
         params.chatId ?? "unknown"
       } total=${webhookStats.received}`,
     );
+  }
   emitDiagnosticEvent({
     type: "webhook.received",
     channel: params.channel,
@@ -125,6 +127,7 @@ export function logWebhookProcessed(params: {
   durationMs?: number;
 }) {
   webhookStats.processed += 1;
+  if (diag.isEnabled("debug")) {
     diag.debug(
       `webhook processed: channel=${params.channel} type=${
         params.updateType ?? "unknown"
@@ -132,6 +135,7 @@ export function logWebhookProcessed(params: {
         webhookStats.processed
       }`,
     );
+  }
   emitDiagnosticEvent({
     type: "webhook.processed",
     channel: params.channel,
@@ -173,11 +177,13 @@ export function logMessageQueued(params: {
   const state = getSessionState(params);
   state.queueDepth += 1;
   state.lastActivity = Date.now();
+  if (diag.isEnabled("debug")) {
     diag.debug(
       `message queued: sessionId=${state.sessionId ?? "unknown"} sessionKey=${
         state.sessionKey ?? "unknown"
       } source=${params.source} queueDepth=${state.queueDepth} sessionState=${state.state}`,
     );
+  }
   emitDiagnosticEvent({
     type: "message.queued",
     sessionId: state.sessionId,
@@ -200,6 +206,8 @@ export function logMessageProcessed(params: {
   reason?: string;
   error?: string;
 }) {
+  const wantsLog = params.outcome === "error" ? diag.isEnabled("error") : diag.isEnabled("debug");
+  if (wantsLog) {
     const payload = `message processed: channel=${params.channel} chatId=${
       params.chatId ?? "unknown"
     } messageId=${params.messageId ?? "unknown"} sessionId=${
@@ -211,11 +219,10 @@ export function logMessageProcessed(params: {
     }`;
     if (params.outcome === "error") {
       diag.error(payload);
-  } else if (params.outcome === "skipped") {
-    diag.debug(payload);
     } else {
       diag.debug(payload);
     }
+  }
   emitDiagnosticEvent({
     type: "message.processed",
     channel: params.channel,
@@ -245,7 +252,7 @@ export function logSessionStateChange(
   if (params.state === "idle") {
     state.queueDepth = Math.max(0, state.queueDepth - 1);
   }
-  if (!isProbeSession) {
+  if (!isProbeSession && diag.isEnabled("debug")) {
     diag.debug(
       `session state: sessionId=${state.sessionId ?? "unknown"} sessionKey=${
         state.sessionKey ?? "unknown"