fleetd #537: pin CapturedLog.close()'s appender-detach and setLevel-immunity contracts

Only the level-restore half of close() was pinned before this
(WorktreeSessionManagerTest). Deleting logger.detachAppender(appender)
from close() left mvn clean install green (1701 tests, 0 failures) --
the appender-detach half of the contract was unmeasured.

Adds CapturedLogTest with three tests, each using a logger name no
production class uses:
- closeDetachesTheAppenderSoALaterLogIsNotCaptured: an event logged
  after close() must not land in events().
- closeRestoresTheLevelCapturedAtOpen: the helper's headline contract
  in one place, independent of any production class.
- setLevelDuringCaptureDoesNotChangeWhatCloseRestores: setLevel()'s
  own javadoc claim that close() always restores the level captured
  at construction, never a value set through setLevel() mid-capture.

Test-only change; CapturedLog.java itself is untouched.

fleetd/src/test/java/dev/ltms/fleet/FleetdAwaitHerdrTest.java

@@ -1,14 +1,12 @@
 package dev.ltms.fleet;
 
 import ch.qos.logback.classic.Level;
-import ch.qos.logback.classic.Logger;
 import ch.qos.logback.classic.spi.ILoggingEvent;
-import ch.qos.logback.core.read.ListAppender;
 import com.fasterxml.jackson.databind.JsonNode;
 import dev.ltms.fleet.herdr.HerdrClient;
 import dev.ltms.fleet.herdr.HerdrException;
+import dev.ltms.fleet.testing.CapturedLog;
 import org.junit.jupiter.api.Test;
-import org.slf4j.LoggerFactory;
 
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.LongSupplier;
@@ -92,49 +90,42 @@ class FleetdAwaitHerdrTest {
 
     @Test
     void answeredLogsNothingAndSaysReap() {
-        ListAppender<ILoggingEvent> events = attach();
-        try {
+        try (CapturedLog log = attach()) {
             boolean shouldReap = Fleetd.logHerdrWaitOutcomeAndShouldReap(
                     new Fleetd.HerdrAwaitOutcome(Fleetd.HerdrWaitResult.ANSWERED, 0L));
 
             assertTrue(shouldReap, "only ANSWERED should tell main to reap orphan workers");
-            assertEquals(0, events.list.size(), "the answered path logs nothing itself");
-        } finally {
-            detach(events);
+            assertEquals(0, log.events().size(), "the answered path logs nothing itself");
         }
     }
 
     @Test
     void deadlinePassedLogsConfiguredAndMeasuredElapsedTogether() {
-        ListAppender<ILoggingEvent> events = attach();
-        try {
+        try (CapturedLog log = attach()) {
             boolean shouldReap = Fleetd.logHerdrWaitOutcomeAndShouldReap(
                     new Fleetd.HerdrAwaitOutcome(Fleetd.HerdrWaitResult.DEADLINE_PASSED, 30_500_000_000L));
 
             assertFalse(shouldReap, "a deadline-passed wait must not tell main to reap");
-            assertEquals(1, events.list.size());
-            ILoggingEvent event = events.list.getFirst();
+            assertEquals(1, log.events().size());
+            ILoggingEvent event = log.events().getFirst();
             assertEquals(Level.WARN, event.getLevel());
             assertEquals("herdr did not answer within the configured wait (configured=30s "
                     + "elapsed=30500ms) — starting anyway; /healthz will report degraded until it "
                     + "comes up. Orphaned worker panes (if any) were NOT reaped.",
                     event.getFormattedMessage());
-        } finally {
-            detach(events);
         }
     }
 
     @Test
     void interruptedLogsItsOwnMessageAndNeverClaimsTheBudgetElapsed() {
-        ListAppender<ILoggingEvent> events = attach();
-        try {
+        try (CapturedLog log = attach()) {
             // 3ms: the ticket's own example of "a few milliseconds in", not the 30s budget.
             boolean shouldReap = Fleetd.logHerdrWaitOutcomeAndShouldReap(
                     new Fleetd.HerdrAwaitOutcome(Fleetd.HerdrWaitResult.INTERRUPTED, 3_000_000L));
 
             assertFalse(shouldReap, "an interrupted wait must not tell main to reap");
-            assertEquals(1, events.list.size());
-            ILoggingEvent event = events.list.getFirst();
+            assertEquals(1, log.events().size());
+            ILoggingEvent event = log.events().getFirst();
             assertEquals(Level.WARN, event.getLevel());
             String message = event.getFormattedMessage();
             assertEquals("herdr wait was interrupted before the configured wait ran out "
@@ -143,8 +134,6 @@ class FleetdAwaitHerdrTest {
                     message);
             assertFalse(message.contains("did not answer"),
                     "an interrupted wait must not be reported as if herdr failed to answer within the budget");
-        } finally {
-            detach(events);
         }
     }
 
@@ -197,16 +186,7 @@ class FleetdAwaitHerdrTest {
         }
     }
 
-    private static ListAppender<ILoggingEvent> attach() {
-        Logger logger = (Logger) LoggerFactory.getLogger(Fleetd.class);
-        logger.setLevel(Level.DEBUG);
-        ListAppender<ILoggingEvent> appender = new ListAppender<>();
-        appender.start();
-        logger.addAppender(appender);
-        return appender;
-    }
-
-    private static void detach(ListAppender<ILoggingEvent> appender) {
-        ((Logger) LoggerFactory.getLogger(Fleetd.class)).detachAppender(appender);
+    private static CapturedLog attach() {
+        return CapturedLog.at(Fleetd.class, Level.DEBUG);
     }
 }

fleetd/src/test/java/dev/ltms/fleet/FleetdLeadMailboxSelectionTest.java

@@ -1,15 +1,12 @@
 package dev.ltms.fleet;
 
 import ch.qos.logback.classic.Level;
-import ch.qos.logback.classic.Logger;
 import ch.qos.logback.classic.spi.ILoggingEvent;
-import ch.qos.logback.core.read.ListAppender;
 import dev.ltms.fleet.config.FleetConfig;
 import dev.ltms.fleet.msg.LeadMailbox;
+import dev.ltms.fleet.testing.CapturedLog;
 import org.junit.jupiter.api.Test;
-import org.slf4j.LoggerFactory;
 
-import java.util.List;
 import java.util.Map;
 
 import static org.junit.jupiter.api.Assertions.*;
@@ -52,29 +49,22 @@ class FleetdLeadMailboxSelectionTest {
         }
     }
 
-    private static ListAppender<ILoggingEvent> captureFleetdLogs() {
-        Logger logger = (Logger) LoggerFactory.getLogger(Fleetd.class);
-        ListAppender<ILoggingEvent> appender = new ListAppender<>();
-        appender.start();
-        logger.addAppender(appender);
-        return appender;
-    }
-
-    private static String joined(ListAppender<ILoggingEvent> appender, Level level) {
-        return appender.list.stream().filter(e -> e.getLevel() == level)
+    private static String joined(CapturedLog captured, Level level) {
+        return captured.events().stream().filter(e -> e.getLevel() == level)
                 .map(ILoggingEvent::getFormattedMessage).reduce("", (a, b) -> a + "\n" + b);
     }
 
     @Test
     void noCoordinatorBlockLeavesTheFeatureOffSilently() {
-        var appender = captureFleetdLogs();
-        var opener = new RecordingOpener();
+        try (var captured = CapturedLog.of(Fleetd.class)) {
+            var opener = new RecordingOpener();
 
-        assertNull(Fleetd.openLeadMailbox(null, Map.of(), opener));
+            assertNull(Fleetd.openLeadMailbox(null, Map.of(), opener));
 
-        assertNull(opener.offeredUri, "nothing configured means nothing is opened");
-        assertEquals("", joined(appender, Level.WARN),
-                "an opt-in feature nobody asked for must not warn on every boot");
+            assertNull(opener.offeredUri, "nothing configured means nothing is opened");
+            assertEquals("", joined(captured, Level.WARN),
+                    "an opt-in feature nobody asked for must not warn on every boot");
+        }
     }
 
     @Test
@@ -114,31 +104,33 @@ class FleetdLeadMailboxSelectionTest {
 
     @Test
     void warnsAndStaysOffWhenSelfIdIsMissing() {
-        var appender = captureFleetdLogs();
-        var opener = new RecordingOpener();
-        var coordinator = new FleetConfig.Coordinator(RESOLVED_URI, null, null, null, null);
+        try (var captured = CapturedLog.of(Fleetd.class)) {
+            var opener = new RecordingOpener();
+            var coordinator = new FleetConfig.Coordinator(RESOLVED_URI, null, null, null, null);
 
-        assertNull(Fleetd.openLeadMailbox(coordinator, Map.of(), opener));
+            assertNull(Fleetd.openLeadMailbox(coordinator, Map.of(), opener));
 
-        assertNull(opener.offeredUri, "a mailbox with no owning coord-id has no queue to declare");
-        String warns = joined(appender, Level.WARN);
-        assertTrue(warns.contains("coordinator.selfId"), () -> "say which key is missing: " + warns);
-        assertFalse(warns.contains(SECRET), () -> "the URI's password must never be logged: " + warns);
+            assertNull(opener.offeredUri, "a mailbox with no owning coord-id has no queue to declare");
+            String warns = joined(captured, Level.WARN);
+            assertTrue(warns.contains("coordinator.selfId"), () -> "say which key is missing: " + warns);
+            assertFalse(warns.contains(SECRET), () -> "the URI's password must never be logged: " + warns);
+        }
     }
 
     @Test
     void warnsAndStaysOffWhenTheBrokerIsUnreachableAtBoot() {
-        var appender = captureFleetdLogs();
-        var opener = new RecordingOpener();
-        opener.unreachable = true;
-        var coordinator = new FleetConfig.Coordinator(RESOLVED_URI, null, "mac-opus", null, null);
+        try (var captured = CapturedLog.of(Fleetd.class)) {
+            var opener = new RecordingOpener();
+            opener.unreachable = true;
+            var coordinator = new FleetConfig.Coordinator(RESOLVED_URI, null, "mac-opus", null, null);
 
-        assertNull(Fleetd.openLeadMailbox(coordinator, Map.of(), opener),
-                "a down coordination broker turns the feature off; it must never take the daemon down");
+            assertNull(Fleetd.openLeadMailbox(coordinator, Map.of(), opener),
+                    "a down coordination broker turns the feature off; it must never take the daemon down");
 
-        String warns = joined(appender, Level.WARN);
-        assertTrue(warns.contains("coord.example"), () -> "name the host that failed: " + warns);
-        assertFalse(warns.contains(SECRET), () -> "with credentials stripped: " + warns);
-        assertTrue(warns.contains("Connection refused"), () -> "and the real reason: " + warns);
+            String warns = joined(captured, Level.WARN);
+            assertTrue(warns.contains("coord.example"), () -> "name the host that failed: " + warns);
+            assertFalse(warns.contains(SECRET), () -> "with credentials stripped: " + warns);
+            assertTrue(warns.contains("Connection refused"), () -> "and the real reason: " + warns);
+        }
     }
 }

fleetd/src/test/java/dev/ltms/fleet/FleetdReplyInboxSelectionTest.java

@@ -1,15 +1,13 @@
 package dev.ltms.fleet;
 
 import ch.qos.logback.classic.Level;
-import ch.qos.logback.classic.Logger;
 import ch.qos.logback.classic.spi.ILoggingEvent;
-import ch.qos.logback.core.read.ListAppender;
 import dev.ltms.fleet.config.FleetConfig;
 import dev.ltms.fleet.msg.AmqpReplyInbox;
 import dev.ltms.fleet.msg.InMemoryReplyInbox;
 import dev.ltms.fleet.msg.ReplyInbox;
+import dev.ltms.fleet.testing.CapturedLog;
 import org.junit.jupiter.api.Test;
-import org.slf4j.LoggerFactory;
 
 import java.net.ServerSocket;
 import java.util.List;
@@ -50,43 +48,34 @@ class FleetdReplyInboxSelectionTest {
         }
     }
 
-    private static ListAppender<ILoggingEvent> attach() {
-        Logger logger = (Logger) LoggerFactory.getLogger(Fleetd.class);
+    private static CapturedLog attach() {
         // logback-test.xml pins dev.ltms.fleet to WARN; raise it so INFO selection lines are captured.
-        logger.setLevel(Level.INFO);
-        ListAppender<ILoggingEvent> appender = new ListAppender<>();
-        appender.start();
-        logger.addAppender(appender);
-        return appender;
+        return CapturedLog.at(Fleetd.class, Level.INFO);
     }
 
-    private static void detach(ListAppender<ILoggingEvent> appender) {
-        ((Logger) LoggerFactory.getLogger(Fleetd.class)).detachAppender(appender);
-    }
-
-    private static void assertNoLogContains(ListAppender<ILoggingEvent> appender, String secret) {
-        assertTrue(appender.list.stream().noneMatch(e -> e.getFormattedMessage().contains(secret)),
+    private static void assertNoLogContains(List<ILoggingEvent> events, String secret) {
+        assertTrue(events.stream().noneMatch(e -> e.getFormattedMessage().contains(secret)),
                 "no log line may contain the resolved URI's password");
     }
 
     @Test
     void uriEnvSetAndPresentSelectsAmqpWithTheResolvedUri() {
         FleetConfig.Broker broker = new FleetConfig.Broker(null, "LAVINMQ_URI", null);
-        recording(broker, Map.of("LAVINMQ_URI", RESOLVED_URI), false, (opener, appender, inbox) -> {
+        recording(broker, Map.of("LAVINMQ_URI", RESOLVED_URI), false, (opener, events, inbox) -> {
             assertEquals(RESOLVED_URI, opener.offeredUri,
                     "the daemon must connect with the value resolved from uriEnv — selection, not just parse");
             assertEquals(opener.inbox, inbox, "the AMQP opener's inbox is what is selected");
-            assertNoLogContains(appender, SECRET);
+            assertNoLogContains(events, SECRET);
         });
     }
 
     @Test
     void uriEnvSetButVariableMissingFallsBackToInMemoryAndWarns() {
         FleetConfig.Broker broker = new FleetConfig.Broker(null, "LAVINMQ_URI", null);
-        recording(broker, Map.of(), false, (opener, appender, inbox) -> {
+        recording(broker, Map.of(), false, (opener, events, inbox) -> {
             assertInstanceOf(InMemoryReplyInbox.class, inbox);
             assertNull(opener.offeredUri, "AMQP must never be attempted when the variable is missing");
-            assertTrue(hasWarnContaining(appender, "LAVINMQ_URI") && hasWarnContaining(appender, "DISABLED"),
+            assertTrue(hasWarnContaining(events, "LAVINMQ_URI") && hasWarnContaining(events, "DISABLED"),
                     "a missing uriEnv variable must warn loudly, not fail silently");
         });
     }
@@ -94,10 +83,10 @@ class FleetdReplyInboxSelectionTest {
     @Test
     void uriEnvSetButVariableBlankFallsBackToInMemoryAndWarns() {
         FleetConfig.Broker broker = new FleetConfig.Broker("amqp://user:lame@old:5672/", "LAVINMQ_URI", null);
-        recording(broker, Map.of("LAVINMQ_URI", "   "), false, (opener, appender, inbox) -> {
+        recording(broker, Map.of("LAVINMQ_URI", "   "), false, (opener, events, inbox) -> {
             assertInstanceOf(InMemoryReplyInbox.class, inbox);
             assertNull(opener.offeredUri, "a blank env value must not select AMQP, not even via the literal uri");
-            assertTrue(hasWarnContaining(appender, "LAVINMQ_URI"),
+            assertTrue(hasWarnContaining(events, "LAVINMQ_URI"),
                     "a blank uriEnv value must warn, and must not fall back to the literal uri");
         });
     }
@@ -106,22 +95,22 @@ class FleetdReplyInboxSelectionTest {
     void bothUriAndUriEnvSetUriEnvWinsDeterministically() {
         FleetConfig.Broker broker
                 = new FleetConfig.Broker("amqp://user:oldpw@old.example:5672/", "LAVINMQ_URI", null);
-        recording(broker, Map.of("LAVINMQ_URI", RESOLVED_URI), false, (opener, appender, inbox) -> {
+        recording(broker, Map.of("LAVINMQ_URI", RESOLVED_URI), false, (opener, events, inbox) -> {
             assertEquals(RESOLVED_URI, opener.offeredUri,
                     "uriEnv must win over uri, deterministically, every run");
-            assertTrue(appender.list.stream().anyMatch(e -> e.getFormattedMessage().contains("broker.uri is ignored")),
+            assertTrue(events.stream().anyMatch(e -> e.getFormattedMessage().contains("broker.uri is ignored")),
                     "must log that the literal uri is ignored when uriEnv is set");
-            assertNoLogContains(appender, SECRET);
-            assertNoLogContains(appender, "oldpw");
+            assertNoLogContains(events, SECRET);
+            assertNoLogContains(events, "oldpw");
         });
     }
 
     @Test
     void unreachableBrokerStartsDaemonWithInMemoryInboxAndLoudWarning() {
         FleetConfig.Broker broker = new FleetConfig.Broker(null, "LAVINMQ_URI", null);
-        recording(broker, Map.of("LAVINMQ_URI", RESOLVED_URI), true, (opener, appender, inbox) -> {
+        recording(broker, Map.of("LAVINMQ_URI", RESOLVED_URI), true, (opener, events, inbox) -> {
             assertInstanceOf(InMemoryReplyInbox.class, inbox, "an unreachable broker must NOT stop the daemon");
-            String warn = appender.list.stream()
+            String warn = events.stream()
                     .filter(e -> e.getLevel() == Level.WARN)
                     .map(ILoggingEvent::getFormattedMessage)
                     .reduce("", (a, b) -> a + "\n" + b)
@@ -129,16 +118,16 @@ class FleetdReplyInboxSelectionTest {
             assertTrue(warn.contains("durable") && warn.contains("soft-state"),
                     "the warning must say exactly what was lost: durable delivery off, replies soft-state");
             assertTrue(!warn.contains(SECRET), "the failing URI must be logged with credentials stripped");
-            assertNoLogContains(appender, SECRET);
+            assertNoLogContains(events, SECRET);
         });
     }
 
     @Test
     void noBrokerConfiguredStaysQuietInMemory() {
         FleetConfig.Broker broker = null;
-        recording(broker, Map.of(), false, (opener, appender, inbox) -> {
+        recording(broker, Map.of(), false, (opener, events, inbox) -> {
             assertInstanceOf(InMemoryReplyInbox.class, inbox);
-            assertTrue(appender.list.stream().noneMatch(e -> e.getLevel() == Level.WARN),
+            assertTrue(events.stream().noneMatch(e -> e.getLevel() == Level.WARN),
                     "no broker configured must keep the existing QUIET in-memory path — no warning");
         });
     }
@@ -152,21 +141,18 @@ class FleetdReplyInboxSelectionTest {
             closedPort = s.getLocalPort();
         }
         FleetConfig.Broker broker = new FleetConfig.Broker(null, "LAVINMQ_URI", null);
-        ListAppender<ILoggingEvent> appender = attach();
-        try {
+        try (CapturedLog log = attach()) {
             ReplyInbox inbox = Fleetd.selectReplyInbox(
                     broker, Map.of("LAVINMQ_URI", "amqp://user:" + SECRET + "@127.0.0.1:" + closedPort + "/vh"),
                     AmqpReplyInbox::open);
             assertInstanceOf(InMemoryReplyInbox.class, inbox,
                     "a genuinely unreachable broker (real AmqpReplyInbox::open) must fall back to in-memory");
-        } finally {
-            detach(appender);
+            assertNoLogContains(log.events(), SECRET);
         }
-        assertNoLogContains(appender, SECRET);
     }
 
-    private boolean hasWarnContaining(ListAppender<ILoggingEvent> appender, String fragment) {
-        return appender.list.stream().anyMatch(e ->
+    private boolean hasWarnContaining(List<ILoggingEvent> events, String fragment) {
+        return events.stream().anyMatch(e ->
                 e.getLevel() == Level.WARN && e.getFormattedMessage().contains(fragment));
     }
 
@@ -174,18 +160,14 @@ class FleetdReplyInboxSelectionTest {
     private void recording(FleetConfig.Broker broker, Map<String, String> env, boolean unreachable, Check check) {
         RecordingAmqp opener = new RecordingAmqp();
         opener.unreachable = unreachable;
-        ListAppender<ILoggingEvent> appender = attach();
-        ReplyInbox inbox;
-        try {
-            inbox = Fleetd.selectReplyInbox(broker, env, opener);
-        } finally {
-            detach(appender);
+        try (CapturedLog log = attach()) {
+            ReplyInbox inbox = Fleetd.selectReplyInbox(broker, env, opener);
+            check.run(opener, log.events(), inbox);
         }
-        check.run(opener, appender, inbox);
     }
 
     @FunctionalInterface
     private interface Check {
-        void run(RecordingAmqp opener, ListAppender<ILoggingEvent> appender, ReplyInbox inbox);
+        void run(RecordingAmqp opener, List<ILoggingEvent> events, ReplyInbox inbox);
     }
 }

fleetd/src/test/java/dev/ltms/fleet/auth/AuditLogTest.java

@@ -1,15 +1,12 @@
 package dev.ltms.fleet.auth;
 
 import ch.qos.logback.classic.Level;
-import ch.qos.logback.classic.LoggerContext;
-import ch.qos.logback.classic.spi.ILoggingEvent;
-import ch.qos.logback.core.read.ListAppender;
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import dev.ltms.fleet.testing.CapturedLog;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
-import org.slf4j.LoggerFactory;
 
 import static org.junit.jupiter.api.Assertions.*;
 
@@ -24,28 +21,21 @@ import static org.junit.jupiter.api.Assertions.*;
 class AuditLogTest {
 
     private final ObjectMapper mapper = new ObjectMapper();
-    private ListAppender<ILoggingEvent> appender;
-    private ch.qos.logback.classic.Logger auditLogger;
+    private CapturedLog auditLog;
 
     @BeforeEach
     void attach() {
-        LoggerContext ctx = (LoggerContext) LoggerFactory.getILoggerFactory();
-        auditLogger = ctx.getLogger("audit");
-        appender = new ListAppender<>();
-        appender.setContext(ctx);
-        appender.start();
-        auditLogger.addAppender(appender);
-        auditLogger.setLevel(Level.INFO);
+        auditLog = CapturedLog.at("audit", Level.INFO);
     }
 
     @AfterEach
     void detach() {
-        auditLogger.detachAppender(appender);
+        auditLog.close();
     }
 
     private JsonNode onlyRecord() throws Exception {
-        assertEquals(1, appender.list.size(), "exactly one audit line expected");
-        String line = appender.list.getFirst().getFormattedMessage();
+        assertEquals(1, auditLog.events().size(), "exactly one audit line expected");
+        String line = auditLog.events().getFirst().getFormattedMessage();
         return mapper.readTree(line); // throws if the line is not valid JSON
     }
 

fleetd/src/test/java/dev/ltms/fleet/inject/CompletionResolverTest.java

@@ -1,9 +1,7 @@
 package dev.ltms.fleet.inject;
 
 import ch.qos.logback.classic.Level;
-import ch.qos.logback.classic.LoggerContext;
 import ch.qos.logback.classic.spi.ILoggingEvent;
-import ch.qos.logback.core.read.ListAppender;
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import dev.ltms.fleet.herdr.AgentControl;
@@ -12,8 +10,8 @@ import dev.ltms.fleet.herdr.HerdrClient;
 import dev.ltms.fleet.msg.Rendezvous;
 import dev.ltms.fleet.msg.TestTurnTokens;
 import dev.ltms.fleet.msg.TurnToken;
+import dev.ltms.fleet.testing.CapturedLog;
 import org.junit.jupiter.api.Test;
-import org.slf4j.LoggerFactory;
 
 import java.util.Set;
 import java.util.regex.Pattern;
@@ -470,15 +468,7 @@ class CompletionResolverTest {
         // CB-564: this used to be a bare DEBUG "failed send to X via turn-stall fallback" — a symptom
         // with no cause, and below the level anyone watching for member health would see. A fail that
         // resolves a caller's blocked send is at least WARN and must carry the reason.
-        LoggerContext ctx = (LoggerContext) LoggerFactory.getILoggerFactory();
-        ch.qos.logback.classic.Logger resolverLog =
-                (ch.qos.logback.classic.Logger) LoggerFactory.getLogger(CompletionResolver.class);
-        ListAppender<ILoggingEvent> appender = new ListAppender<>();
-        appender.setContext(ctx);
-        appender.start();
-        resolverLog.addAppender(appender);
-        resolverLog.setLevel(Level.WARN);
-        try {
+        try (CapturedLog log = CapturedLog.at(CompletionResolver.class, Level.WARN)) {
             FakeHerdr herdr = new FakeHerdr().readText("stuck on an error screen");
             Rendezvous rendezvous = new Rendezvous();
             CompletionResolver resolver = new CompletionResolver(new AgentControl(herdr), rendezvous, ExhaustedPatternLookup.none(), ExhaustionSink.none());
@@ -486,7 +476,7 @@ class CompletionResolverTest {
 
             resolver.fail("term_a", null);
 
-            String warn = appender.list.stream()
+            String warn = log.events().stream()
                     .filter(e -> e.getLevel().equals(Level.WARN))
                     .map(ILoggingEvent::getFormattedMessage)
                     .findFirst()
@@ -494,8 +484,6 @@ class CompletionResolverTest {
             assertTrue(warn.contains("term_a"), "the log names the target: " + warn);
             assertTrue(warn.contains("stuck on an error screen"), "the log carries the reason: " + warn);
             assertTrue(waiter.isDone());
-        } finally {
-            resolverLog.detachAppender(appender);
         }
     }
 

fleetd/src/test/java/dev/ltms/fleet/inject/InjectorTest.java

@@ -1,16 +1,14 @@
 package dev.ltms.fleet.inject;
 
 import ch.qos.logback.classic.Level;
-import ch.qos.logback.classic.LoggerContext;
 import ch.qos.logback.classic.spi.ILoggingEvent;
-import ch.qos.logback.core.read.ListAppender;
 import dev.ltms.fleet.herdr.AgentControl;
 import dev.ltms.fleet.herdr.AgentStatus;
 import dev.ltms.fleet.herdr.FakeHerdr;
 import dev.ltms.fleet.herdr.HerdrException;
 import dev.ltms.fleet.msg.TestTurnTokens;
+import dev.ltms.fleet.testing.CapturedLog;
 import org.junit.jupiter.api.Test;
-import org.slf4j.LoggerFactory;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -493,23 +491,15 @@ class InjectorTest {
     void readinessGraceExpiryIsLogged() {
         // CB-562: the grace-expiry path used to clear the queue silently, so a message that never
         // reached the worker's pane surfaced elsewhere as an unrelated turn-stall failure. Assert the
-        // expiry now names the real cause. (ListAppender capture pattern mirrors AuditLogTest.)
-        LoggerContext ctx = (LoggerContext) LoggerFactory.getILoggerFactory();
-        ch.qos.logback.classic.Logger injectorLog =
-                (ch.qos.logback.classic.Logger) LoggerFactory.getLogger(Injector.class);
-        ListAppender<ILoggingEvent> appender = new ListAppender<>();
-        appender.setContext(ctx);
-        appender.start();
-        injectorLog.addAppender(appender);
-        injectorLog.setLevel(Level.WARN);
-        try {
+        // expiry now names the real cause. (CapturedLog pattern mirrors AuditLogTest.)
+        try (CapturedLog log = CapturedLog.at(Injector.class, Level.WARN)) {
             Injector inj = new Injector(new AgentControl(herdr), TurnListener.NOOP, _ -> false, _ -> {
             });
             inj.enqueue(T, "task", TestTurnTokens.inert(T));
 
             for (int i = 0; i < READINESS_SAMPLES; i++) inj.onStatus(T, AgentStatus.IDLE);
 
-            String warn = appender.list.stream()
+            String warn = log.events().stream()
                     .filter(e -> e.getLevel().equals(Level.WARN))
                     .map(ILoggingEvent::getFormattedMessage)
                     .findFirst()
@@ -518,8 +508,6 @@ class InjectorTest {
             assertTrue(warn.contains("never reached"), "the log names the real cause: " + warn);
             assertTrue(warn.contains("1 queued message"),
                     "the log carries the failed message count: " + warn);
-        } finally {
-            injectorLog.detachAppender(appender);
         }
     }
 
@@ -533,22 +521,14 @@ class InjectorTest {
         // count and a labelled configured budget, using literal numbers (240, 60), never
         // READINESS_GRACE_POLLS or POLL_INTERVAL_MILLIS, so the assertion can't silently track a
         // constant change instead of catching a real regression.
-        LoggerContext ctx = (LoggerContext) LoggerFactory.getILoggerFactory();
-        ch.qos.logback.classic.Logger injectorLog =
-                (ch.qos.logback.classic.Logger) LoggerFactory.getLogger(Injector.class);
-        ListAppender<ILoggingEvent> appender = new ListAppender<>();
-        appender.setContext(ctx);
-        appender.start();
-        injectorLog.addAppender(appender);
-        injectorLog.setLevel(Level.WARN);
-        try {
+        try (CapturedLog log = CapturedLog.at(Injector.class, Level.WARN)) {
             Injector inj = new Injector(new AgentControl(herdr), TurnListener.NOOP, _ -> false, _ -> {
             });
             inj.enqueue(T, "task", TestTurnTokens.inert(T));
 
             for (int i = 0; i < READINESS_SAMPLES; i++) inj.onStatus(T, AgentStatus.IDLE);
 
-            String warn = appender.list.stream()
+            String warn = log.events().stream()
                     .filter(e -> e.getLevel().equals(Level.WARN))
                     .map(ILoggingEvent::getFormattedMessage)
                     .findFirst()
@@ -557,8 +537,6 @@ class InjectorTest {
                     "must print the measured poll count as a plain number: " + warn);
             assertTrue(warn.contains("configured=240 polls/60s"),
                     "must print the configured budget, clearly labelled: " + warn);
-        } finally {
-            injectorLog.detachAppender(appender);
         }
     }
 
@@ -584,22 +562,14 @@ class InjectorTest {
             return readings[i];
         };
 
-        LoggerContext ctx = (LoggerContext) LoggerFactory.getILoggerFactory();
-        ch.qos.logback.classic.Logger injectorLog =
-                (ch.qos.logback.classic.Logger) LoggerFactory.getLogger(Injector.class);
-        ListAppender<ILoggingEvent> appender = new ListAppender<>();
-        appender.setContext(ctx);
-        appender.start();
-        injectorLog.addAppender(appender);
-        injectorLog.setLevel(Level.WARN);
-        try {
+        try (CapturedLog log = CapturedLog.at(Injector.class, Level.WARN)) {
             Injector inj = new Injector(new AgentControl(herdr), TurnListener.NOOP, _ -> false, _ -> {
             }, stubClock);
             inj.enqueue(T, "task", TestTurnTokens.inert(T));
 
             for (int i = 0; i < READINESS_SAMPLES; i++) inj.onStatus(T, AgentStatus.IDLE);
 
-            String warn = appender.list.stream()
+            String warn = log.events().stream()
                     .filter(e -> e.getLevel().equals(Level.WARN))
                     .map(ILoggingEvent::getFormattedMessage)
                     .findFirst()
@@ -609,8 +579,6 @@ class InjectorTest {
             assertFalse(warn.contains("elapsed=60000ms"), "must not print "
                     + "READINESS_GRACE_POLLS * POLL_INTERVAL_MILLIS (240 * 250 = 60000ms) as if it "
                     + "were the measured elapsed time: " + warn);
-        } finally {
-            injectorLog.detachAppender(appender);
         }
     }
 
@@ -647,21 +615,13 @@ class InjectorTest {
         // CB-564: a vanished worker used to drop its queue with no log at all — the only trace was
         // whatever failed downstream (e.g. a caller's send timing out with no clue why). Assert the
         // drop itself now names the cause and the number of messages it failed.
-        LoggerContext ctx = (LoggerContext) LoggerFactory.getILoggerFactory();
-        ch.qos.logback.classic.Logger injectorLog =
-                (ch.qos.logback.classic.Logger) LoggerFactory.getLogger(Injector.class);
-        ListAppender<ILoggingEvent> appender = new ListAppender<>();
-        appender.setContext(ctx);
-        appender.start();
-        injectorLog.addAppender(appender);
-        injectorLog.setLevel(Level.WARN);
-        try {
+        try (CapturedLog log = CapturedLog.at(Injector.class, Level.WARN)) {
             Injector inj = new Injector(new AgentControl(herdr), TurnListener.NOOP, _ -> true, _ -> {
             });
             inj.enqueue(T, "orphan", TestTurnTokens.inert(T));
             inj.drop(T, new HerdrException("worker gone", "pane_not_found", null));
 
-            String warn = appender.list.stream()
+            String warn = log.events().stream()
                     .filter(e -> e.getLevel().equals(Level.WARN))
                     .map(ILoggingEvent::getFormattedMessage)
                     .findFirst()
@@ -669,8 +629,6 @@ class InjectorTest {
             assertTrue(warn.contains(T), "the log names the target terminal: " + warn);
             assertTrue(warn.contains("1 message"), "the log carries the failed message count: " + warn);
             assertTrue(warn.contains("worker gone"), "the log carries the real cause: " + warn);
-        } finally {
-            injectorLog.detachAppender(appender);
         }
     }
 

fleetd/src/test/java/dev/ltms/fleet/lead/LeadRolloverTest.java

@@ -1,23 +1,22 @@
 package dev.ltms.fleet.lead;
 
 import ch.qos.logback.classic.Level;
-import ch.qos.logback.classic.Logger;
 import ch.qos.logback.classic.spi.ILoggingEvent;
-import ch.qos.logback.core.read.ListAppender;
 import com.fasterxml.jackson.databind.JsonNode;
 import dev.ltms.fleet.config.FleetConfig;
 import dev.ltms.fleet.herdr.AgentControl;
 import dev.ltms.fleet.herdr.FakeHerdr;
 import dev.ltms.fleet.herdr.HerdrClient;
 import dev.ltms.fleet.herdr.HerdrException;
+import dev.ltms.fleet.testing.CapturedLog;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
-import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.util.List;
 import java.util.concurrent.atomic.AtomicLong;
 import java.util.function.Function;
 import java.util.function.LongSupplier;
@@ -862,25 +861,16 @@ class LeadRolloverTest {
 
     // ---- fleetd #494: the log lines must print MEASURED values, never the configured budget --
 
-    private static ListAppender<ILoggingEvent> attachLog() {
-        Logger logger = (Logger) LoggerFactory.getLogger(LeadRollover.class);
-        logger.setLevel(Level.DEBUG);
-        ListAppender<ILoggingEvent> appender = new ListAppender<>();
-        appender.start();
-        logger.addAppender(appender);
-        return appender;
+    private static CapturedLog attachLog() {
+        return CapturedLog.at(LeadRollover.class, Level.DEBUG);
     }
 
-    private static void detachLog(ListAppender<ILoggingEvent> appender) {
-        ((Logger) LoggerFactory.getLogger(LeadRollover.class)).detachAppender(appender);
-    }
-
-    private static ILoggingEvent lastEventContaining(ListAppender<ILoggingEvent> events, String substring) {
-        return events.list.stream()
+    private static ILoggingEvent lastEventContaining(List<ILoggingEvent> events, String substring) {
+        return events.stream()
                 .filter(e -> e.getFormattedMessage().contains(substring))
                 .reduce((_, b) -> b)
                 .orElseThrow(() -> new AssertionError("no log event contained \"" + substring
-                        + "\"; got: " + events.list.stream().map(ILoggingEvent::getFormattedMessage).toList()));
+                        + "\"; got: " + events.stream().map(ILoggingEvent::getFormattedMessage).toList()));
     }
 
     @Test
@@ -914,15 +904,14 @@ class LeadRolloverTest {
         AtomicLong clock = new AtomicLong(1_000);
         LeadRollover rollover = newRollover(flipsAfterClear, config, () -> clock.addAndGet(500));
 
-        ListAppender<ILoggingEvent> events = attachLog();
-        try {
+        try (CapturedLog log = attachLog()) {
             LeadRollover.PendingRollover pending = rollover.open(LEAD, "context is full");
             LeadRollover.RollDecision decision = rollover.confirm(LEAD, pending.token(), true);
 
             assertTrue(decision.accepted(), "every synchronous gate passes; the refusal is logged "
                     + "only, deep inside the deferred continuation");
 
-            ILoggingEvent event = lastEventContaining(events, "NOT sending bootstrapText");
+            ILoggingEvent event = lastEventContaining(log.events(), "NOT sending bootstrapText");
             assertEquals(Level.WARN, event.getLevel());
             String message = event.getFormattedMessage();
             assertTrue(message.contains("configured=1s"), "must label the configured budget: " + message);
@@ -934,8 +923,6 @@ class LeadRolloverTest {
                     + message);
             assertFalse(message.contains("within 1s"), "must not present the configured budget as if "
                     + "it were the measured wait duration: " + message);
-        } finally {
-            detachLog(events);
         }
     }
 
@@ -954,15 +941,14 @@ class LeadRolloverTest {
         AtomicLong clock = new AtomicLong(1_000);
         LeadRollover rollover = newRollover(herdr, config, () -> clock.addAndGet(500));
 
-        ListAppender<ILoggingEvent> events = attachLog();
-        try {
+        try (CapturedLog log = attachLog()) {
             LeadRollover.PendingRollover pending = rollover.open(LEAD, "context is full");
             LeadRollover.RollDecision decision = rollover.confirm(LEAD, pending.token(), true);
 
             assertTrue(decision.accepted(), "expected approval; got: " + decision.reason()
                     + " / " + decision.detail());
 
-            ILoggingEvent event = lastEventContaining(events, "releasing rather than wedging the roll");
+            ILoggingEvent event = lastEventContaining(log.events(), "releasing rather than wedging the roll");
             assertEquals(Level.WARN, event.getLevel(), "the grace-limit release must be WARN, not "
                     + "INFO — it is exactly the case that reported false success in the real incident "
                     + "this fix comes from (a roll that 'succeeded' after 438ms of a 20s budget)");
@@ -982,8 +968,6 @@ class LeadRolloverTest {
             assertTrue(message.contains("after 8 consecutive IDLE/DONE polls (7 of those were nudged)"),
                     "must print the measured poll count and nudge count as plain numbers, not the "
                             + "PICKUP_GRACE_POLLS constant standing in for either: " + message);
-        } finally {
-            detachLog(events);
         }
     }
 
@@ -1000,15 +984,14 @@ class LeadRolloverTest {
         AtomicLong clock = new AtomicLong(1_000);
         LeadRollover rollover = newRollover(herdr, config, () -> clock.addAndGet(500));
 
-        ListAppender<ILoggingEvent> events = attachLog();
-        try {
+        try (CapturedLog log = attachLog()) {
             LeadRollover.PendingRollover pending = rollover.open(LEAD, "context is full");
             LeadRollover.RollDecision decision = rollover.confirm(LEAD, pending.token(), true);
 
             assertTrue(decision.accepted(), "expected approval; got: " + decision.reason()
                     + " / " + decision.detail());
 
-            ILoggingEvent event = lastEventContaining(events, "lead-rollover: rolled");
+            ILoggingEvent event = lastEventContaining(log.events(), "lead-rollover: rolled");
             assertEquals(Level.INFO, event.getLevel());
             String message = event.getFormattedMessage();
             // fleetd #494 follow-up: waitUntilAtTurnBoundary now also reads the injected clock one
@@ -1018,8 +1001,6 @@ class LeadRolloverTest {
             assertTrue(message.contains("elapsedMs=7000"), "must print the MEASURED elapsed time for "
                     + "the whole roll — with this fixture's advancing clock, the full roll (turn-settle "
                     + "wait + /clear wait + bootstrapText) took 7000ms: " + message);
-        } finally {
-            detachLog(events);
         }
     }
 
@@ -1040,8 +1021,7 @@ class LeadRolloverTest {
         AtomicLong clock = new AtomicLong(1_000);
         LeadRollover rollover = newRollover(herdr, config, () -> clock.addAndGet(500));
 
-        ListAppender<ILoggingEvent> events = attachLog();
-        try {
+        try (CapturedLog log = attachLog()) {
             LeadRollover.PendingRollover pending = rollover.open(LEAD, "context is full");
             LeadRollover.RollDecision decision = rollover.confirm(LEAD, pending.token(), true);
 
@@ -1049,7 +1029,7 @@ class LeadRolloverTest {
                     + "only inside the deferred continuation, which this test's synchronous runner "
                     + "has already run to completion by the time confirm() returns");
 
-            ILoggingEvent event = lastEventContaining(events, "refusing to send /clear at all");
+            ILoggingEvent event = lastEventContaining(log.events(), "refusing to send /clear at all");
             assertEquals(Level.WARN, event.getLevel());
             String message = event.getFormattedMessage();
             assertTrue(message.contains("configured=1s"), "must label the configured budget: " + message);
@@ -1058,8 +1038,6 @@ class LeadRolloverTest {
                     + "1s(=1000ms) configured budget: " + message);
             assertFalse(message.contains("within 1s"), "must not present the configured budget as if "
                     + "it were the measured wait duration: " + message);
-        } finally {
-            detachLog(events);
         }
     }
 }

fleetd/src/test/java/dev/ltms/fleet/msg/AmqpConnectionFailureLoggerTest.java

@@ -1,17 +1,17 @@
 package dev.ltms.fleet.msg;
 
 import ch.qos.logback.classic.Level;
-import ch.qos.logback.classic.Logger;
 import ch.qos.logback.classic.spi.ILoggingEvent;
-import ch.qos.logback.core.read.ListAppender;
 import com.rabbitmq.client.Channel;
 import com.rabbitmq.client.ConnectionFactory;
 import com.rabbitmq.client.impl.DefaultExceptionHandler;
+import dev.ltms.fleet.testing.CapturedLog;
 import org.junit.jupiter.api.Test;
 import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
 import java.lang.reflect.Proxy;
+import java.util.List;
 import java.util.concurrent.atomic.AtomicInteger;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
@@ -32,21 +32,17 @@ class AmqpConnectionFailureLoggerTest {
         assertEquals(AmqpConnectionFailureLogger.REPLY_INBOX, inboxHandler.connectionName());
         assertEquals(AmqpConnectionFailureLogger.LEAD_MAILBOX, mailboxHandler.connectionName());
 
-        ListAppender<ILoggingEvent> inboxEvents = attach(AmqpReplyInbox.class);
-        ListAppender<ILoggingEvent> mailboxEvents = attach(LeadMailbox.class);
         IllegalStateException inboxFailure = new IllegalStateException("inbox failure");
         IllegalStateException mailboxFailure = new IllegalStateException("mailbox failure");
-        try {
+        try (CapturedLog inboxLog = attach(AmqpReplyInbox.class);
+             CapturedLog mailboxLog = attach(LeadMailbox.class)) {
             inboxHandler.handleUnexpectedConnectionDriverException(null, inboxFailure);
             mailboxHandler.handleConnectionRecoveryException(null, mailboxFailure);
 
-            assertError(inboxEvents, "AMQP connection fleetd-reply-inbox: An unexpected connection driver error occurred",
+            assertError(inboxLog.events(), "AMQP connection fleetd-reply-inbox: An unexpected connection driver error occurred",
                     inboxFailure, "inbox failure line");
-            assertError(mailboxEvents, "AMQP connection fleetd-lead-mailbox: Caught an exception during connection recovery!",
+            assertError(mailboxLog.events(), "AMQP connection fleetd-lead-mailbox: Caught an exception during connection recovery!",
                     mailboxFailure, "mailbox recovery line");
-        } finally {
-            detach(AmqpReplyInbox.class, inboxEvents);
-            detach(LeadMailbox.class, mailboxEvents);
         }
     }
 
@@ -54,17 +50,14 @@ class AmqpConnectionFailureLoggerTest {
     void connectionResetKeepsForgivingHandlerWarningSemantics() {
         AmqpConnectionFailureLogger handler = new AmqpConnectionFailureLogger(
                 AmqpConnectionFailureLogger.REPLY_INBOX, LoggerFactory.getLogger(AmqpReplyInbox.class));
-        ListAppender<ILoggingEvent> events = attach(AmqpReplyInbox.class);
-        try {
+        try (CapturedLog log = attach(AmqpReplyInbox.class)) {
             handler.handleUnexpectedConnectionDriverException(null, new IOException("Connection reset"));
-            assertEquals(1, events.list.size(), "the handler must still log a reset");
-            ILoggingEvent event = events.list.getFirst();
+            assertEquals(1, log.events().size(), "the handler must still log a reset");
+            ILoggingEvent event = log.events().getFirst();
             assertEquals(Level.WARN, event.getLevel(), "ForgivingExceptionHandler logs connection resets at WARN");
             assertEquals("AMQP connection fleetd-reply-inbox: An unexpected connection driver error occurred "
                             + "(Exception message: Connection reset)", event.getFormattedMessage());
             assertTrue(event.getThrowableProxy() == null, "ForgivingExceptionHandler does not attach a reset stack trace");
-        } finally {
-            detach(AmqpReplyInbox.class, events);
         }
     }
 
@@ -103,17 +96,8 @@ class AmqpConnectionFailureLoggerTest {
                 "all exception-handling methods must remain inherited from DefaultExceptionHandler");
     }
 
-    private static ListAppender<ILoggingEvent> attach(Class<?> owner) {
-        Logger logger = (Logger) LoggerFactory.getLogger(owner);
-        logger.setLevel(Level.DEBUG);
-        ListAppender<ILoggingEvent> appender = new ListAppender<>();
-        appender.start();
-        logger.addAppender(appender);
-        return appender;
-    }
-
-    private static void detach(Class<?> owner, ListAppender<ILoggingEvent> appender) {
-        ((Logger) LoggerFactory.getLogger(owner)).detachAppender(appender);
+    private static CapturedLog attach(Class<?> owner) {
+        return CapturedLog.at(owner, Level.DEBUG);
     }
 
     private static AmqpConnectionFailureLogger installedStrictHandler(ConnectionFactory factory, String connection) {
@@ -123,9 +107,9 @@ class AmqpConnectionFailureLoggerTest {
         return assertInstanceOf(AmqpConnectionFailureLogger.class, factory.getExceptionHandler());
     }
 
-    private static void assertError(ListAppender<ILoggingEvent> events, String message, Throwable cause, String name) {
-        assertEquals(1, events.list.size(), name);
-        ILoggingEvent event = events.list.getFirst();
+    private static void assertError(List<ILoggingEvent> events, String message, Throwable cause, String name) {
+        assertEquals(1, events.size(), name);
+        ILoggingEvent event = events.getFirst();
         assertEquals(Level.ERROR, event.getLevel(), name);
         assertEquals(message, event.getFormattedMessage(), name);
         assertEquals(cause.toString(), event.getThrowableProxy().getClassName() + ": "

fleetd/src/test/java/dev/ltms/fleet/session/GitWorktreesTest.java

@@ -1,16 +1,13 @@
 package dev.ltms.fleet.session;
 
 import ch.qos.logback.classic.Level;
-import ch.qos.logback.classic.Logger;
-import ch.qos.logback.classic.LoggerContext;
 import ch.qos.logback.classic.spi.IThrowableProxy;
 import ch.qos.logback.classic.spi.ILoggingEvent;
-import ch.qos.logback.core.read.ListAppender;
+import dev.ltms.fleet.testing.CapturedLog;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
-import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
 import java.nio.charset.StandardCharsets;
@@ -489,36 +486,33 @@ class GitWorktreesTest {
     // ---- CB-189: broader remote-URL coverage — every remote, both fetch and push URLs, any
     // non-SSH scheme. Reporting only, additive to the origin/https strip-and-refuse tests above. ----
 
-    private Logger reportingLogger;
-    private ListAppender<ILoggingEvent> reportingAppender;
+    private CapturedLog reportingLog;
 
     /** {@link GitWorktrees}'s own logger, captured fresh for each test so assertions never see a
-     *  message left over from a previous test. */
+     *  message left over from a previous test. fleetd #529: {@link CapturedLog#close} restores the
+     *  level it captured here (whatever it truly was before this test, not just WARN), so a test
+     *  below that further lowers the level to INFO for its own assertion (via {@link
+     *  #reportingLog}'s {@link CapturedLog#setLevel}) can never leak that INFO pin past its own
+     *  {@code @AfterEach} — every test's window is self-contained. */
     @BeforeEach
     void attachReportingLogCapture() {
-        LoggerContext ctx = (LoggerContext) LoggerFactory.getILoggerFactory();
-        reportingLogger = ctx.getLogger(GitWorktrees.class);
-        reportingLogger.setLevel(Level.WARN);
-        reportingAppender = new ListAppender<>();
-        reportingAppender.setContext(ctx);
-        reportingAppender.start();
-        reportingLogger.addAppender(reportingAppender);
+        reportingLog = CapturedLog.at(GitWorktrees.class, Level.WARN);
     }
 
     @AfterEach
     void detachReportingLogCapture() {
-        reportingLogger.detachAppender(reportingAppender);
+        reportingLog.close();
     }
 
     private List<String> capturedMessages() {
-        return reportingAppender.list.stream().map(ILoggingEvent::getFormattedMessage).toList();
+        return reportingLog.events().stream().map(ILoggingEvent::getFormattedMessage).toList();
     }
 
     /** Asserts {@code secret} appears in no captured message, and in no attached exception's
      *  message either — the constraint is that a credential must never reach a log, however it
      *  would have gotten there. */
     private void assertNoLeak(String secret) {
-        for (ILoggingEvent event : reportingAppender.list) {
+        for (ILoggingEvent event : reportingLog.events()) {
             assertFalse(event.getFormattedMessage().contains(secret),
                     "log message leaked a credential (" + secret + "): " + event.getFormattedMessage());
             IThrowableProxy thrown = event.getThrowableProxy();
@@ -596,7 +590,7 @@ class GitWorktreesTest {
 
         new GitWorktrees(tmp.resolve("wts").toString()).add(repo.toString(), "cb-189-d", "HEAD");
 
-        assertTrue(reportingAppender.list.isEmpty(),
+        assertTrue(reportingLog.events().isEmpty(),
                 "expected no report for an ssh remote and a credential-free https remote, got:\n"
                         + capturedMessages());
     }
@@ -812,7 +806,7 @@ class GitWorktreesTest {
     /** Criterion 1, all three present: the summary names the denominator and every neutralized file. */
     @Test
     void isolateToolSurfaceLogsAllThreeConfigsNeutralized(@TempDir Path tmp) throws Exception {
-        reportingLogger.setLevel(Level.INFO);
+        reportingLog.setLevel(Level.INFO);
         Path repo = initRepoWithAllThreeConfigs(tmp.resolve("repo"));
 
         new GitWorktrees(tmp.resolve("wts").toString()).add(repo.toString(), "cb-134-log-all", "HEAD");
@@ -827,7 +821,7 @@ class GitWorktreesTest {
     /** Criterion 1, two absent: the summary must still name the denominator and say why. */
     @Test
     void isolateToolSurfaceLogsAbsentConfigsWithReason(@TempDir Path tmp) throws Exception {
-        reportingLogger.setLevel(Level.INFO);
+        reportingLog.setLevel(Level.INFO);
         Path repo = initRepo(tmp.resolve("repo")); // only .mcp.json + README committed
 
         new GitWorktrees(tmp.resolve("wts").toString()).add(repo.toString(), "cb-134-log-partial", "HEAD");
@@ -1435,7 +1429,7 @@ class GitWorktreesTest {
     /** Criterion 2: both candidates present — the summary line names both and the denominator. */
     @Test
     void overlayParityLogsBothCopiedWhenBothCandidatesArePresent(@TempDir Path tmp) throws Exception {
-        reportingLogger.setLevel(Level.INFO);
+        reportingLog.setLevel(Level.INFO);
         Path repo = initRepo(tmp.resolve("repo"));
         Files.writeString(repo.resolve(".env"), "A=1\n");
         Files.writeString(repo.resolve(".envrc"), "export A=1\n");
@@ -1452,7 +1446,7 @@ class GitWorktreesTest {
      *  denominator, and why the other candidate was not copied. */
     @Test
     void overlayParityLogsOneCopiedOneAbsent(@TempDir Path tmp) throws Exception {
-        reportingLogger.setLevel(Level.INFO);
+        reportingLog.setLevel(Level.INFO);
         Path repo = initRepo(tmp.resolve("repo"));
         Files.writeString(repo.resolve(".env"), "A=1\n");
         // .envrc deliberately not created — the absent candidate.
@@ -1472,7 +1466,7 @@ class GitWorktreesTest {
      *  change, silently, unless this line told it so beforehand. */
     @Test
     void overlayParityLogsSkipWorktreeConsequenceForATrackedFile(@TempDir Path tmp) throws Exception {
-        reportingLogger.setLevel(Level.INFO);
+        reportingLog.setLevel(Level.INFO);
         Path repo = initRepo(tmp.resolve("repo"));
         Files.writeString(repo.resolve(".env"), "A=1\n");
         git(repo, "add", ".env");
@@ -1495,7 +1489,7 @@ class GitWorktreesTest {
     /** Criterion 5: null and empty overlay lists return quietly — no exception, no log noise. */
     @Test
     void overlayParityWithNoCandidatesLogsNothing(@TempDir Path tmp) throws Exception {
-        reportingLogger.setLevel(Level.INFO);
+        reportingLog.setLevel(Level.INFO);
         Path repo = initRepo(tmp.resolve("repo"));
         Path wt = bareWorktree(repo, tmp.resolve("wt"), "cb134-empty");
         GitWorktrees worktrees = new GitWorktrees(tmp.resolve("wts").toString());
@@ -1503,7 +1497,7 @@ class GitWorktreesTest {
         worktrees.overlayParity(repo.toString(), wt.toString(), null);
         worktrees.overlayParity(repo.toString(), wt.toString(), List.of());
 
-        assertTrue(reportingAppender.list.isEmpty(),
+        assertTrue(reportingLog.events().isEmpty(),
                 "a null/empty overlay must log nothing, got:\n" + capturedMessages());
     }
 
@@ -1683,7 +1677,7 @@ class GitWorktreesTest {
      *  denominator, what was seeded, and what was kept because the repo already had it. */
     @Test
     void seedSkillsLogsSeededAndKept(@TempDir Path tmp) throws Exception {
-        reportingLogger.setLevel(Level.INFO);
+        reportingLog.setLevel(Level.INFO);
         Path repo = tmp.resolve("repo");
         Files.createDirectories(repo);
         git(repo, "init", "-q", "-b", "main");

fleetd/src/test/java/dev/ltms/fleet/session/SessionManagerTest.java

@@ -1,9 +1,7 @@
 package dev.ltms.fleet.session;
 
 import ch.qos.logback.classic.Level;
-import ch.qos.logback.classic.LoggerContext;
 import ch.qos.logback.classic.spi.ILoggingEvent;
-import ch.qos.logback.core.read.ListAppender;
 import dev.ltms.fleet.auth.MemberRegistry;
 import dev.ltms.fleet.auth.MemberLifecycle;
 import dev.ltms.fleet.config.ConfigRef;
@@ -25,6 +23,7 @@ import dev.ltms.fleet.peer.SpawnRequest;
 import dev.ltms.fleet.placement.BackendQuarantine;
 import dev.ltms.fleet.placement.PlacementDecision;
 import dev.ltms.fleet.placement.PlacementPolicies;
+import dev.ltms.fleet.testing.CapturedLog;
 import org.junit.jupiter.api.AfterAll;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.MethodOrderer;
@@ -123,54 +122,8 @@ class SessionManagerTest {
         return new SessionManager(workers, worktrees, clock);
     }
 
-    /**
-     * fleetd #525: captures a logger's output and, on {@link #close}, restores <em>both</em> the
-     * appender and the level to what they were before. A bare {@code addAppender}/{@code
-     * setLevel} pair whose {@code finally} only detaches the appender leaves the level pinned —
-     * {@code ch.qos.logback.classic.Logger} instances are cached per class and shared across the
-     * whole JVM, so a level set by one test in this class is still in effect for every test that
-     * runs after it, in this class or any other. try-with-resources makes "restored the appender
-     * but not the level" impossible to write, because there is only one thing to close.
-     */
-    private static final class CapturedLog implements AutoCloseable {
-        private final ch.qos.logback.classic.Logger logger;
-        private final Level originalLevel;
-        private final ListAppender<ILoggingEvent> appender;
-
-        private CapturedLog(Class<?> loggerClass, Level pinnedLevel) {
-            LoggerContext ctx = (LoggerContext) LoggerFactory.getILoggerFactory();
-            this.logger = (ch.qos.logback.classic.Logger) LoggerFactory.getLogger(loggerClass);
-            this.originalLevel = logger.getLevel();
-            this.appender = new ListAppender<>();
-            appender.setContext(ctx);
-            appender.start();
-            logger.addAppender(appender);
-            if (pinnedLevel != null) {
-                logger.setLevel(pinnedLevel);
-            }
-        }
-
-        /** Capture {@code loggerClass}'s output, pinning its level to {@code pinnedLevel} for the
-         *  duration of the try-with-resources block. */
-        static CapturedLog at(Class<?> loggerClass, Level pinnedLevel) {
-            return new CapturedLog(loggerClass, pinnedLevel);
-        }
-
-        /** Capture {@code loggerClass}'s output without changing its level. */
-        static CapturedLog of(Class<?> loggerClass) {
-            return new CapturedLog(loggerClass, null);
-        }
-
-        List<ILoggingEvent> events() {
-            return appender.list;
-        }
-
-        @Override
-        public void close() {
-            logger.detachAppender(appender);
-            logger.setLevel(originalLevel);
-        }
-    }
+    // fleetd #529: CapturedLog moved to dev.ltms.fleet.testing.CapturedLog (imported above) so
+    // every test file shares one implementation instead of each hand-rolling its own capture.
 
     /**
      * CB-581: a {@link Worktrees} test double whose {@code hasUncommitted} and {@code remove} can

fleetd/src/test/java/dev/ltms/fleet/session/WorktreeSessionManagerTest.java

@@ -7,13 +7,17 @@ import dev.ltms.fleet.herdr.AgentControl;
 import dev.ltms.fleet.herdr.FakeHerdr;
 import dev.ltms.fleet.herdr.WorkspaceControl;
 import ch.qos.logback.classic.Level;
-import ch.qos.logback.classic.LoggerContext;
 import ch.qos.logback.classic.spi.ILoggingEvent;
-import ch.qos.logback.core.read.ListAppender;
 import dev.ltms.fleet.member.ClaudeCodeLauncher;
 import dev.ltms.fleet.msg.TestTurnTokens;
 import dev.ltms.fleet.peer.MemberRole;
+import dev.ltms.fleet.testing.CapturedLog;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.MethodOrderer;
+import org.junit.jupiter.api.Order;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestMethodOrder;
 import org.slf4j.LoggerFactory;
 
 import java.util.List;
@@ -27,9 +31,41 @@ import static org.junit.jupiter.api.Assertions.*;
  * CB-301-ext acceptance tests for worktree provisioning and config-parity overlay.
  * No live git — every Worktrees call is handled by {@link FakeWorktrees} and every herdr
  * call by {@link FakeHerdr}, matching the project's fake-based test style.
+ *
+ * <p>fleetd #529: only {@link #releasePreservesDirtyWorktreeAndLogsWarn} (explicitly
+ * {@link Order#value() @Order(1)}) and the proving test right after it
+ * ({@link #sharedSessionManagerLoggerLevelIsRestoredAfterDirtyWorktreeReleasePinsWarn},
+ * {@code @Order(2)}) care about method order — every other test here has no {@code @Order} and so
+ * runs after both (JUnit 5's {@link MethodOrderer.OrderAnnotation} gives an unannotated method the
+ * lowest priority), in whatever relative order it already ran in.
  */
+@TestMethodOrder(MethodOrderer.OrderAnnotation.class)
 class WorktreeSessionManagerTest {
 
+    /**
+     * fleetd #529: the level {@link SessionManager}'s logger had when this class started, captured
+     * before any test here touches it, then forced to a distinctive, known value (TRACE) so {@link
+     * #sharedSessionManagerLoggerLevelIsRestoredAfterDirtyWorktreeReleasePinsWarn} can tell "the
+     * level came back to what it was" apart from "the level happens to already be WARN because
+     * some other test class in this JVM fork (surefire reuses forks by default) left it there".
+     */
+    private static ch.qos.logback.classic.Level sessionManagerLevelBeforeThisClass;
+
+    @BeforeAll
+    static void pinSessionManagerLoggerToAKnownBaseline() {
+        ch.qos.logback.classic.Logger sessionLog =
+                (ch.qos.logback.classic.Logger) LoggerFactory.getLogger(SessionManager.class);
+        sessionManagerLevelBeforeThisClass = sessionLog.getLevel();
+        sessionLog.setLevel(ch.qos.logback.classic.Level.TRACE);
+    }
+
+    @AfterAll
+    static void restoreSessionManagerLoggerLevel() {
+        ch.qos.logback.classic.Logger sessionLog =
+                (ch.qos.logback.classic.Logger) LoggerFactory.getLogger(SessionManager.class);
+        sessionLog.setLevel(sessionManagerLevelBeforeThisClass);
+    }
+
     private static MemberRegistry members() {
         return new MemberRegistry(new FleetConfig.Fleet(Map.of(),
                 Map.of("architect", new FleetConfig.Slot("ltms-local")),
@@ -254,6 +290,7 @@ class WorktreeSessionManagerTest {
      * path, the session, and the cause an operator needs to find the work.
      */
     @Test
+    @Order(1)
     void releasePreservesDirtyWorktreeAndLogsWarn() {
         FakeHerdr herdr = new FakeHerdr();
         FakeWorktrees worktrees = new FakeWorktrees().withRepoRoot("/repo").withPrefix("/wt")
@@ -262,21 +299,13 @@ class WorktreeSessionManagerTest {
         MemberSession s = sessions.acquire("ltms-local", null, "/caller/proj", null,
                 new WorktreeRequest("cb-576", null));
 
-        LoggerContext ctx = (LoggerContext) LoggerFactory.getILoggerFactory();
-        ch.qos.logback.classic.Logger sessionLog =
-                (ch.qos.logback.classic.Logger) LoggerFactory.getLogger(SessionManager.class);
-        ListAppender<ILoggingEvent> appender = new ListAppender<>();
-        appender.setContext(ctx);
-        appender.start();
-        sessionLog.addAppender(appender);
-        sessionLog.setLevel(Level.WARN);
-        try {
+        try (CapturedLog log = CapturedLog.at(SessionManager.class, Level.WARN)) {
             sessions.release(s.paneId());
 
             assertTrue(herdr.called("pane.close"), "release still tears the worker pane down");
             assertTrue(worktrees.removeCalls().isEmpty(),
                     "a dirty worktree is never removed — it holds the only copy of the work");
-            String warn = appender.list.stream()
+            String warn = log.events().stream()
                     .filter(e -> e.getLevel().equals(Level.WARN))
                     .map(ILoggingEvent::getFormattedMessage)
                     .filter(m -> m.contains("dirty worktree"))
@@ -285,11 +314,38 @@ class WorktreeSessionManagerTest {
             assertTrue(warn.contains(s.worktree()), "the WARN names the worktree path: " + warn);
             assertTrue(warn.contains(s.terminalId()), "the WARN names the session: " + warn);
             assertTrue(warn.contains("COMPLETED"), "the WARN names the release cause: " + warn);
-        } finally {
-            sessionLog.detachAppender(appender);
         }
     }
 
+    /**
+     * fleetd #529 proving test: pins that the leak this ticket fixes stays fixed. {@link
+     * #releasePreservesDirtyWorktreeAndLogsWarn} above (which runs immediately before this, via
+     * {@code @Order}) pins the shared {@link SessionManager} logger to WARN through a {@link
+     * CapturedLog}; if {@link CapturedLog#close} only detached the appender — the original bug —
+     * the level would still read WARN here instead of the {@code TRACE} baseline this class's
+     * {@code @BeforeAll} set. Runs at {@code @Order(2)}, guaranteed after {@code @Order(1)} and
+     * before every other (unannotated) test in this class.
+     *
+     * <p>This proves only the WITHIN-CLASS case: JUnit 5's {@code @TestMethodOrder} orders methods
+     * inside one class, not test classes relative to each other, and surefire's default class order
+     * is not something a single test can force. The cross-class leak fleetd #525 measured — this
+     * class's {@code releasePreservesDirtyWorktreeAndLogsWarn} pinning WARN and bleeding into a
+     * later-running {@code SessionManagerTest} in the same fork — is fixed by the same {@link
+     * CapturedLog} mechanism proven here, but that cross-class ordering itself is NOT asserted by
+     * any test and remains unproven by construction.
+     */
+    @Test
+    @Order(2)
+    void sharedSessionManagerLoggerLevelIsRestoredAfterDirtyWorktreeReleasePinsWarn() {
+        ch.qos.logback.classic.Logger sessionLog =
+                (ch.qos.logback.classic.Logger) LoggerFactory.getLogger(SessionManager.class);
+        assertEquals(ch.qos.logback.classic.Level.TRACE, sessionLog.getLevel(),
+                "releasePreservesDirtyWorktreeAndLogsWarn pins the shared SessionManager logger to "
+                        + "WARN; its cleanup must restore the level it captured (TRACE, set by this "
+                        + "class's @BeforeAll) rather than leaving WARN pinned for every test that "
+                        + "runs after it");
+    }
+
     /**
      * CB-576 review (fleetd #116). A worktree that is already gone (operator cleanup,
      * {@code git worktree prune}, an earlier half-completed release) must not break teardown.

fleetd/src/test/java/dev/ltms/fleet/testing/CapturedLog.java

@@ -0,0 +1,112 @@
+package dev.ltms.fleet.testing;
+
+import ch.qos.logback.classic.Level;
+import ch.qos.logback.classic.Logger;
+import ch.qos.logback.classic.LoggerContext;
+import ch.qos.logback.classic.spi.ILoggingEvent;
+import ch.qos.logback.core.read.ListAppender;
+import org.slf4j.LoggerFactory;
+
+import java.util.List;
+
+/**
+ * fleetd #529 (promoted from {@code SessionManagerTest}, merged in #527 for fleetd #525): captures
+ * a logger's output and, on {@link #close}, restores <em>both</em> the appender and the level to
+ * what they were before.
+ *
+ * <p>{@code ch.qos.logback.classic.Logger} instances are cached per class and shared across the
+ * whole JVM — and surefire reuses forks by default — so a bare {@code addAppender}/{@code
+ * setLevel} pair whose {@code finally} only detaches the appender leaves the level pinned for
+ * every test that runs after it, in the same class or in a completely unrelated one sharing the
+ * fork. try-with-resources makes "restored the appender but not the level" impossible to write,
+ * because there is only one thing to close.
+ *
+ * <p>New code must use this rather than hand-rolling the {@code ListAppender} + {@code setLevel} +
+ * {@code finally detachAppender} pattern: use {@link #at} or {@link #of}. It is <em>not</em> yet
+ * the only instance of the pattern in this test tree, and the earlier wording here said it was —
+ * which would leave a reader who greps unable to tell a leftover from a violation.
+ *
+ * <p>Measured on main at af95897 (2026-09-12): nine test files still hand-roll it, with 42
+ * {@code setLevel} calls on a raw logback {@code Logger} between them — {@code
+ * FleetdStartupReportTest}, {@code GitHostShapeReportTest}, {@code MemberCredentialsGapReportTest},
+ * {@code MemberTrustModelReportTest}, {@code FleetHealthMonitorTest}, {@code
+ * ClaudeCodeLauncherTest}, {@code HerdrPeerLauncherAllowListWiringTest}, {@code
+ * HerdrPeerLauncherCharterTest} and {@code OpenCodeLauncherTest}. Every one of them pairs its pin
+ * with a restore, so none is the fleetd #525 leak and none was in fleetd #529's scope, which was
+ * the 19 <em>unrestored</em> pins only. They are unmigrated, not broken.
+ *
+ * <p>Re-measure with the two commands below, from the repo root. A file that appears in the first
+ * list and not the second still hand-rolls the pattern. When the first list comes back empty, this
+ * paragraph is spent and the sentence above can go back to saying "the one way" — delete the
+ * paragraph then rather than updating the count.
+ *
+ * <pre>{@code
+ * grep -rlE '\.setLevel\(' fleetd/src/test/java --include='*.java' | grep -v CapturedLog.java
+ * grep -rl 'CapturedLog' fleetd/src/test/java --include='*.java'
+ * }</pre>
+ */
+public final class CapturedLog implements AutoCloseable {
+    private final Logger logger;
+    private final Level originalLevel;
+    private final ListAppender<ILoggingEvent> appender;
+
+    private CapturedLog(Logger logger, Level pinnedLevel) {
+        LoggerContext ctx = (LoggerContext) LoggerFactory.getILoggerFactory();
+        this.logger = logger;
+        this.originalLevel = logger.getLevel();
+        this.appender = new ListAppender<>();
+        appender.setContext(ctx);
+        appender.start();
+        logger.addAppender(appender);
+        if (pinnedLevel != null) {
+            logger.setLevel(pinnedLevel);
+        }
+    }
+
+    /** Capture {@code loggerClass}'s output, pinning its level to {@code pinnedLevel} for the
+     *  duration of the try-with-resources block. */
+    public static CapturedLog at(Class<?> loggerClass, Level pinnedLevel) {
+        return new CapturedLog((Logger) LoggerFactory.getLogger(loggerClass), pinnedLevel);
+    }
+
+    /** Capture {@code loggerClass}'s output without changing its level. */
+    public static CapturedLog of(Class<?> loggerClass) {
+        return new CapturedLog((Logger) LoggerFactory.getLogger(loggerClass), null);
+    }
+
+    /**
+     * Capture the named logger's output, pinning its level to {@code pinnedLevel}. For a logger
+     * obtained in production code via {@code LoggerFactory.getLogger("some-name")} rather than a
+     * class — e.g. {@code AuditLog}'s {@code "audit"} logger — where {@link #at(Class, Level)}
+     * would capture the wrong {@code Logger} instance (class name and logger name are different
+     * strings and resolve to different cached loggers).
+     */
+    public static CapturedLog at(String loggerName, Level pinnedLevel) {
+        return new CapturedLog((Logger) LoggerFactory.getLogger(loggerName), pinnedLevel);
+    }
+
+    /** Capture the named logger's output without changing its level. See {@link #at(String, Level)}. */
+    public static CapturedLog of(String loggerName) {
+        return new CapturedLog((Logger) LoggerFactory.getLogger(loggerName), null);
+    }
+
+    public List<ILoggingEvent> events() {
+        return appender.list;
+    }
+
+    /**
+     * Re-pin the level while this capture is still open — for example to lower it further for one
+     * assertion inside a test whose fixture already pinned a coarser baseline in {@code @BeforeEach}.
+     * This does not change what {@link #close} restores: that is always the level captured when
+     * this instance was created, never a value set through this method.
+     */
+    public void setLevel(Level level) {
+        logger.setLevel(level);
+    }
+
+    @Override
+    public void close() {
+        logger.detachAppender(appender);
+        logger.setLevel(originalLevel);
+    }
+}

fleetd/src/test/java/dev/ltms/fleet/testing/CapturedLogTest.java

@@ -0,0 +1,96 @@
+package dev.ltms.fleet.testing;
+
+import ch.qos.logback.classic.Level;
+import ch.qos.logback.classic.Logger;
+import org.junit.jupiter.api.Test;
+import org.slf4j.LoggerFactory;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+/**
+ * fleetd #537: pins {@link CapturedLog#close}'s own contract — the appender detach half, the level
+ * restore half, and that {@link CapturedLog#setLevel} does not change what {@code close} restores.
+ * Before this, only the level-restore half was pinned (by {@code
+ * WorktreeSessionManagerTest.sharedSessionManagerLoggerLevelIsRestoredAfterDirtyWorktreeReleasePinsWarn}).
+ * Measured: deleting {@code logger.detachAppender(appender);} from {@code close()} still left
+ * {@code mvn clean install} green — 1701 tests, 0 failures — before this file existed.
+ *
+ * <p>Every test below uses a logger name no production class uses, and unique per test, so this
+ * file cannot become the next entry in fleetd #525's leak family: {@link CapturedLog}'s own
+ * javadoc re-measure commands (top of that file) would otherwise need to start naming this class.
+ */
+class CapturedLogTest {
+
+    /**
+     * The appender must be detached on close: an event logged through the raw logger after close
+     * must not land in {@link CapturedLog#events()}. Asserting on the observable list (rather than
+     * {@code logger.iteratorForAppenders()}) is what the ticket asked for, and it is also what a
+     * real leak would actually break — a later test's own {@code ListAppender} silently gaining
+     * events emitted by code under test that has nothing to do with it.
+     */
+    @Test
+    void closeDetachesTheAppenderSoALaterLogIsNotCaptured() {
+        String loggerName = "capturedlog-test-only.appender-detach";
+        Logger rawLogger = (Logger) LoggerFactory.getLogger(loggerName);
+
+        CapturedLog log = CapturedLog.of(loggerName);
+        rawLogger.info("while open");
+        int eventsWhileOpen = log.events().size();
+        assertEquals(1, eventsWhileOpen, "the event logged while open must be captured");
+
+        log.close();
+        rawLogger.info("after close");
+
+        assertEquals(eventsWhileOpen, log.events().size(),
+                "close() must detach the appender: an event logged after close must not be "
+                        + "captured, but the captured list grew from " + eventsWhileOpen + " to "
+                        + log.events().size());
+    }
+
+    /**
+     * The helper's own headline contract, pinned in one place independent of any production
+     * class's behaviour: {@code close()} restores the level the logger had before {@link
+     * CapturedLog#at} pinned it.
+     */
+    @Test
+    void closeRestoresTheLevelCapturedAtOpen() {
+        String loggerName = "capturedlog-test-only.level-restore";
+        Logger rawLogger = (Logger) LoggerFactory.getLogger(loggerName);
+        rawLogger.setLevel(Level.DEBUG);
+
+        CapturedLog log = CapturedLog.at(loggerName, Level.ERROR);
+        assertEquals(Level.ERROR, rawLogger.getLevel(), "the pinned level took effect while open");
+
+        log.close();
+
+        assertEquals(Level.DEBUG, rawLogger.getLevel(),
+                "close() must restore the level captured when at() was called (DEBUG), not leave "
+                        + "the pinned level (ERROR) in place");
+    }
+
+    /**
+     * {@link CapturedLog#setLevel}'s javadoc claims that re-pinning the level mid-capture does not
+     * change what {@code close()} restores — that restore always uses the level captured when the
+     * instance was created, never a value set through {@code setLevel}. Nothing checked this
+     * before: open with a pinned WARN, call {@code setLevel(TRACE)}, close, and the result must be
+     * the level from BEFORE {@code at} — neither WARN nor TRACE.
+     */
+    @Test
+    void setLevelDuringCaptureDoesNotChangeWhatCloseRestores() {
+        String loggerName = "capturedlog-test-only.setlevel-no-effect";
+        Logger rawLogger = (Logger) LoggerFactory.getLogger(loggerName);
+        rawLogger.setLevel(Level.DEBUG);
+
+        CapturedLog log = CapturedLog.at(loggerName, Level.WARN);
+        log.setLevel(Level.TRACE);
+        assertEquals(Level.TRACE, rawLogger.getLevel(), "setLevel took effect immediately");
+
+        log.close();
+
+        assertEquals(Level.DEBUG, rawLogger.getLevel(),
+                "close() must restore the level captured at open (DEBUG) regardless of any "
+                        + "later setLevel() call: it must be neither WARN (the level pinned by "
+                        + "at()) nor TRACE (the level set via setLevel() mid-capture), but got "
+                        + rawLogger.getLevel());
+    }
+}

scripts/redeploy-fleetd.sh

@@ -314,10 +314,12 @@ systemd_loaded() {
 #      never assigned to a global: a global set inside a `$( )` subshell dies with that subshell.
 #      This function packs BOTH values (kind and detail) onto that one stdout line, joined by
 #      $SUPERVISOR_DETAIL_SEP, and the caller unpacks them on its own side of the subshell boundary.
-#   2. This script runs under `set -euo pipefail` (line 50), so an unset variable is a loud
-#      failure. Do not add a `${VAR:-default}` anywhere downstream to paper over a value that
-#      should always be there — that hides a lost value instead of surfacing it (fleetd #497's
-#      defect class).
+#   2. This script runs under `set -u` (part of the `set -euo pipefail` at the top of the file), so
+#      an unset variable is a loud failure. Do not add a `${VAR:-default}` anywhere downstream to
+#      paper over a value that should always be there — that hides a lost value instead of
+#      surfacing it (fleetd #497's defect class). The mechanism is named rather than cited by line
+#      number on purpose: a line number in a comment goes stale on the next insert above it, and
+#      this one already had — it said line 50 while the `set` line was at 54.
 #   3. Every `case` on this function's return value needs an explicit final `*)` arm, chosen by
 #      whether that caller ACTS on the value (`die` — an unrecognised value must never be silently
 #      driven) or only DISPLAYS it (`echo`/`warn` and continue — a diagnostic must not go silent on