fleetd #637: pin the fleet_list window wiring and fold the threshold into the gauge's cache key

Fleetd.leadConfigDirSource built its window argument with nothing calling the
factory itself to prove it, so a mutation to a no-op lookup left the whole
suite green. Add a wiring test that calls the factory directly, modeled on
FleetdLeadConfigDirSourceWiringTest's shape for the configDir half of the
same factory.

LeadContextGauge's result cache keyed only on (configDir, sessionId), but the
cached Reading's state now depends on the caller's resolved effective window.
Fold the derived threshold into the cache key so two reads of the same
session with different windows inside the TTL each report against their own
window.

fleetd/src/main/java/dev/ltms/fleet/lead/LeadContextGauge.java

@@ -68,8 +68,10 @@ import java.util.function.LongSupplier;
  * (never the whole 52 MB a long-lived transcript reaches on the host this was measured on), and
  * {@link #DEFAULT_CACHE_TTL_MILLIS} bounds how often that bounded read actually happens — a burst
  * of {@code fleet_list} calls inside one TTL window reads the file once. One instance's cache is
- * keyed by {@code (configDir, sessionId)}, so it is safe to share across every lead a single
- * {@code fleet_list} call reports on.
+ * keyed by {@code (configDir, sessionId, highThreshold)}, so it is safe to share across every lead
+ * a single {@code fleet_list} call reports on, and a call that resolves a different effective
+ * window for the same lead never reads back a state computed against the other window's
+ * threshold.
  */
 public final class LeadContextGauge {
 
@@ -192,13 +194,14 @@ public final class LeadContextGauge {
         String base = (configDir == null || configDir.isBlank())
                 ? System.getProperty("user.home") + "/.claude"
                 : configDir;
-        String cacheKey = base + '\u0000' + sessionId;
+        long highThreshold = highThreshold(effectiveWindowTokens);
+        String cacheKey = base + '\u0000' + sessionId + '\u0000' + highThreshold;
         long now = clock.getAsLong();
         CacheEntry cached = cache.get(cacheKey);
         if (cached != null && now - cached.readAtMillis() < ttlMillis) {
             return cached.reading();
         }
-        Reading fresh = readUncached(base, sessionId, highThreshold(effectiveWindowTokens));
+        Reading fresh = readUncached(base, sessionId, highThreshold);
         cache.put(cacheKey, new CacheEntry(fresh, now));
         return fresh;
     }

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

@@ -0,0 +1,63 @@
+package dev.ltms.fleet;
+
+import dev.ltms.fleet.config.FleetConfig;
+import dev.ltms.fleet.mcp.FleetMcp;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+/**
+ * Pins {@link Fleetd#leadConfigDirSource}'s own wiring of the window lookup into the returned
+ * {@link FleetMcp.LeadConfigDirSource}, not only the detached {@link Fleetd#leadContextWindowLookup}
+ * factory it delegates to. Calls the producer directly, with real {@link FleetConfig.Profile}/
+ * {@link FleetConfig.Leader} fixtures, and asserts on {@code windowFor()} — the companion of
+ * {@link FleetdLeadConfigDirSourceWiringTest}, which pins the same factory's {@code configDirFor()}.
+ */
+class FleetdLeadConfigDirSourceWindowWiringTest {
+
+    private static FleetConfig.Profile profileWithWindow(String name, Integer autoCompactWindow) {
+        return new FleetConfig.Profile(name, null, "claude-sonnet-5", null, null, null,
+                "tab", "fleet", "w #{n}", null, null, null, null, null, null, null,
+                null, null, true, null, null, null, null, null, autoCompactWindow, null);
+    }
+
+    private static FleetConfig.Leader leadOnProfile(String profile) {
+        return new FleetConfig.Leader(profile, "lead: primary", 1, "lead:", 10, "claude", "claude-sonnet-5");
+    }
+
+    @Test
+    @DisplayName("the returned source resolves the lead's REAL configured effective window, not a hardcoded null")
+    void resolvesTheRealConfiguredWindow() {
+        Map<String, FleetConfig.Profile> profiles = Map.of("opus", profileWithWindow("opus", 250_000));
+        Map<String, FleetConfig.Leader> leaders = Map.of("primary", leadOnProfile("opus"));
+
+        FleetMcp.LeadConfigDirSource source = Fleetd.leadConfigDirSource(() -> profiles, leaders);
+
+        assertEquals(250_000L, source.windowFor().apply("primary"),
+                "windowFor must delegate to the real leadContextWindowLookup, not a stub that always "
+                        + "returns null");
+    }
+
+    @Test
+    @DisplayName("a lead on a profile with no window configured still resolves to null, not a crash")
+    void leadWithNoWindowConfiguredResolvesToNull() {
+        Map<String, FleetConfig.Profile> profiles = Map.of("opus", profileWithWindow("opus", null));
+        Map<String, FleetConfig.Leader> leaders = Map.of("primary", leadOnProfile("opus"));
+
+        FleetMcp.LeadConfigDirSource source = Fleetd.leadConfigDirSource(() -> profiles, leaders);
+
+        assertNull(source.windowFor().apply("primary"));
+    }
+
+    @Test
+    @DisplayName("an unrecognised lead name resolves to null, not a thrown exception")
+    void unrecognisedLeadNameResolvesToNull() {
+        FleetMcp.LeadConfigDirSource source = Fleetd.leadConfigDirSource(Map::of, Map.of());
+
+        assertNull(source.windowFor().apply("ghost-lead"));
+    }
+}

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

@@ -88,4 +88,23 @@ class LeadContextGaugeHighThresholdTest {
                 legacyGauge.read(legacyConfigDir, SESSION_ID, "claude").state(),
                 "the 3-arg read() (no window argument at all) must behave exactly like passing a null window");
     }
+
+    @Test
+    @DisplayName("a second read with a different window, within the TTL, reports against its own window, not the first call's cached state")
+    void aSecondReadWithADifferentWindowWithinTheTtlReportsAgainstItsOwnWindow(@TempDir Path tmp) throws IOException {
+        String configDir = writeTranscript(tmp, SESSION_ID, 90_000);
+        long[] now = {0L};
+        LeadContextGauge gauge = new LeadContextGauge(() -> now[0], 5_000);
+
+        LeadContextGauge.Reading first = gauge.read(configDir, SESSION_ID, "claude", 100_000L);
+        assertEquals(LeadContextGauge.State.HIGH, first.state(),
+                "90,000 tokens against a 100,000 window is HIGH");
+
+        now[0] += 1_000; // stays inside the 5,000ms TTL — the cache key must still vary with the window
+        LeadContextGauge.Reading second = gauge.read(configDir, SESSION_ID, "claude", 1_000_000L);
+
+        assertEquals(LeadContextGauge.State.OK, second.state(),
+                "90,000 tokens against a 1,000,000 window must report OK regardless of the previous call's "
+                        + "window, even while that call's cache entry is still within its TTL");
+    }
 }