diff --git a/src/__tests__/logger.test.ts b/src/__tests__/logger.test.ts
index d395716..19042e0 100644
--- a/src/__tests__/logger.test.ts
+++ b/src/__tests__/logger.test.ts
@@ -69,7 +69,7 @@ test('level-gated methods do not emit when disabled', async () => {
     assert.equal(debugCalls.length, 0, 'debug should be suppressed at warn level');
     assert.equal(infoCalls.length, 0, 'info should be suppressed at warn level');
     assert.equal(warnCalls.length, 1, 'warn should pass at warn level');
-    assert.match(warnCalls[0], /\[WARN\] \[test\/ctx\] warn-detail/);
+    assert.match(warnCalls[0], /^\[\d{4}-\d{2}-\d{2}T[^\]]+\] WARN \[test\/ctx\] warn-detail$/);
   } finally {
     console.debug = origDebug;
     console.info = origInfo;
@@ -86,7 +86,7 @@ test('debug emits when level is debug', async () => {
     logger.setLevel('debug');
     logger.debug('test/ctx', 'detail');
     assert.equal(calls.length, 1);
-    assert.match(calls[0], /\[DEBUG\] \[test\/ctx\] detail/);
+    assert.match(calls[0], /^\[\d{4}-\d{2}-\d{2}T[^\]]+\] DEBUG \[test\/ctx\] detail$/);
   } finally {
     console.debug = orig;
   }
@@ -103,7 +103,7 @@ test('error always emits at any level that includes error', async () => {
       calls.length = 0;
       await logger.error('test/ctx', 'err-detail');
       assert.equal(calls.length, 1, `error should fire at level=${level}`);
-      assert.match(calls[0], /\[ERROR\] \[test\/ctx\] err-detail/);
+      assert.match(calls[0], /^\[\d{4}-\d{2}-\d{2}T[^\]]+\] ERROR \[test\/ctx\] err-detail$/);
     }
   } finally {
     console.error = orig;
diff --git a/src/core/logger.ts b/src/core/logger.ts
index d0bb26d..e062cc2 100644
--- a/src/core/logger.ts
+++ b/src/core/logger.ts
@@ -32,17 +32,13 @@ function formatEntry(level: string, context: string, detail: string): string {
   return `[${ts}] ${level} [${sanitize(context)}] ${sanitize(detail)}\n`;
 }
 
-function formatLine(level: string, context: string, detail: string): string {
-  return `[${level}] [${sanitize(context)}] ${sanitize(detail)}`;
-}
-
 function shouldEmit(level: LogLevel): boolean {
   return LEVELS[level] >= currentLevel;
 }
 
 function emit(level: LogLevel, context: string, detail: string, sink: (line: string) => void) {
   if (!shouldEmit(level)) return;
-  sink(formatLine(level.toUpperCase(), context, detail));
+  sink(formatEntry(level.toUpperCase(), context, detail).trimEnd());
 }
 
 export const logger = {
@@ -68,7 +64,7 @@ export const logger = {
     emit('warn', context, detail, (line) => console.warn(line));
   },
   async error(context: string, detail: string): Promise<void> {
-    if (shouldEmit('error')) console.error(formatLine('ERROR', context, detail));
+    if (shouldEmit('error')) console.error(formatEntry('ERROR', context, detail).trimEnd());
     try {
       await ensureDir();
       await appendFile(LOG_FILE, formatEntry('ERROR', context, detail));