fix(timeline): clear multi-select on drag start and lock in SSE edge-case coverage

- useTimelineDrag: onProjectBarMouseDown and single-alloc drag path now reset
  multiSelectRef + multiSelectState before starting a new drag, so the
  FloatingActionBar is dismissed immediately when an unrelated drag begins
- FloatingActionBar.test.tsx: 4 regression tests for the null-render guard
  (count=0) and all three label variants
- useTimelineSSE.test.ts: 2 new tests — tab hides during pending reconnect
  timer (clears timer, resyncs on next open) and first-ever connection fails
  before any open (retry open still resyncs correctly)
- assistant-tools-user-admin-inventory-read.test.ts: add isActive to expected
  findMany select shape (already in production, test was stale)

Co-Authored-By: claude-flow <ruv@ruv.net>

apps/web/src/hooks/useTimelineDrag.ts

@@ -496,6 +496,8 @@ export function useTimelineDrag({
       },
     ) => {
       if (e.button !== 0) return;
+      multiSelectRef.current = INITIAL_MULTI_SELECT;
+      setMultiSelectState(INITIAL_MULTI_SELECT);
       e.preventDefault();
       e.stopPropagation();
       const state = createProjectDragState<DragState>({
@@ -610,6 +612,8 @@ export function useTimelineDrag({
 
       // ── Single allocation drag ────────────────────────────────────────────
 
+      multiSelectRef.current = INITIAL_MULTI_SELECT;
+      setMultiSelectState(INITIAL_MULTI_SELECT);
       const initial = createAllocationDragState<AllocDragState, AllocDragMode, AllocDragScope>({
         mode: opts.mode,
         scope: opts.scope,

apps/web/src/hooks/useTimelineSSE.test.ts

@@ -240,4 +240,58 @@ describe("useTimelineSSE", () => {
       getTimelineSseResyncKeys().map((queryKey) => [{ queryKey }]),
     );
   });
+
+  it("hides during pending reconnect timer — clears timer and resyncs on next open", () => {
+    useTimelineSSE();
+
+    const firstConnection = MockEventSource.instances[0];
+    expect(firstConnection).toBeDefined();
+
+    // Establish connection, then break it — schedules a 2s reconnect timer
+    firstConnection?.emitOpen();
+    firstConnection?.emitError(); // shouldResyncOnOpen = true, timer scheduled
+
+    // Tab hides while timer is still pending (no active `es`)
+    mockDocument.setVisibility("hidden"); // clears timer, shouldResyncOnOpen stays true
+
+    // No timer should fire — still only one EventSource
+    vi.advanceTimersByTime(5_000);
+    expect(MockEventSource.instances).toHaveLength(1);
+
+    // Tab becomes visible — should connect fresh
+    mockDocument.setVisibility("visible");
+    expect(MockEventSource.instances).toHaveLength(2);
+
+    // Successful open on the new connection → resync
+    const secondConnection = MockEventSource.instances[1];
+    secondConnection?.emitOpen();
+
+    expect(invalidateQueries).toHaveBeenCalledTimes(getTimelineSseResyncKeys().length);
+    expect(invalidateQueries.mock.calls).toEqual(
+      getTimelineSseResyncKeys().map((queryKey) => [{ queryKey }]),
+    );
+  });
+
+  it("resyncs after the first-ever connection attempt fails before any open", () => {
+    useTimelineSSE();
+
+    const firstConnection = MockEventSource.instances[0];
+    expect(firstConnection).toBeDefined();
+
+    // Error fires without any preceding open — shouldResyncOnOpen becomes true
+    firstConnection?.emitError();
+
+    // Advance past the 2s backoff
+    vi.advanceTimersByTime(2_000);
+    expect(MockEventSource.instances).toHaveLength(2);
+
+    // Retry succeeds
+    const secondConnection = MockEventSource.instances[1];
+    secondConnection?.emitOpen();
+
+    expect(invalidateQueries).toHaveBeenCalledTimes(getTimelineSseResyncKeys().length);
+    expect(invalidateQueries.mock.calls).toEqual(
+      getTimelineSseResyncKeys().map((queryKey) => [{ queryKey }]),
+    );
+  });
 });