diff --git a/gitnexus/src/core/group/sync.ts b/gitnexus/src/core/group/sync.ts
index 5c535f29f..a329500be 100644
Binary files a/gitnexus/src/core/group/sync.ts and b/gitnexus/src/core/group/sync.ts differ
diff --git a/gitnexus/src/core/lbug/pool-adapter.ts b/gitnexus/src/core/lbug/pool-adapter.ts
index e5338e3d0..11b1f7690 100644
--- a/gitnexus/src/core/lbug/pool-adapter.ts
+++ b/gitnexus/src/core/lbug/pool-adapter.ts
@@ -103,6 +103,31 @@ const IDLE_TIMEOUT_MS = 5 * 60 * 1000; // 5 minutes
 /** Max connections per repo (caps concurrent queries per repo) */
 const MAX_CONNS_PER_REPO = 8;
 
+/**
+ * Repos exempt from AUTOMATIC eviction (LRU + idle timeout) until explicitly
+ * unpinned. Used by bounded multi-repo operations like `group sync`, which
+ * initializes one pool per repo and then resolves cross-repo manifest/workspace
+ * links against ALL of those pools after the init loop. Without pinning, a
+ * group larger than MAX_POOL_SIZE would LRU-evict the earliest repos before
+ * resolution runs, leaving the deferred executor closures pointing at dead pool
+ * entries (issue #2189).
+ *
+ * Pins are REFERENCE-COUNTED: the map holds repoId → active lease count. This
+ * lets overlapping holders (two windows of one sync, or two concurrent
+ * `group sync` calls sharing a repo) coexist safely — the repo stays exempt
+ * until the LAST holder releases. A boolean Set could not represent "two
+ * holders," so the first release would wrongly clear a pin another holder still
+ * needs (PR #2191 review, Finding 1).
+ *
+ * Pins block only automatic eviction (LRU + idle). Explicit teardown
+ * (closeOne / closeLbug) always closes the entry and force-clears its count —
+ * teardown is authoritative. A present key always means count ≥ 1. While every
+ * pooled repo is pinned, evictLRU finds no eligible victim and the pool may
+ * transiently exceed MAX_POOL_SIZE — the same soft-cap behavior that already
+ * occurs when every entry is checked out.
+ */
+const pinnedRepos = new Map<string, number>();
+
 // Behavior-neutral RSS tracing for the FTS evict→reload memory repro
 // (gitnexus/scripts/bench/fts-evict-reload-rss.mjs). Two invariants keep it safe
 // in the pool init/close hot path: it writes ONLY to stderr (stdout is the MCP
@@ -145,6 +170,7 @@ function ensureIdleTimer(): void {
   idleTimer = setInterval(() => {
     const now = Date.now();
     for (const [repoId, entry] of pool) {
+      if (pinnedRepos.has(repoId)) continue;
       if (now - entry.lastUsed > IDLE_TIMEOUT_MS && entry.checkedOut === 0) {
         closeOne(repoId);
       }
@@ -167,7 +193,64 @@ export const touchRepo = (repoId: string): void => {
 };
 
 /**
- * Evict the least-recently-used repo if pool is at capacity
+ * Acquire one eviction-exemption lease on a repo (LRU + idle timeout) by
+ * incrementing its reference count. The repoId must match the key passed to
+ * initLbug (e.g. group sync leases by handle.id — the same id it inits with).
+ * Leasing a repoId before it enters the pool is allowed and protects the entry
+ * once it is created, but the lease does NOT survive a teardown: closeOne
+ * force-clears the count, so a later re-init of the same repoId starts
+ * unpinned. Each pinRepo MUST be balanced by exactly one release (the repo
+ * stays exempt until the last lease is released). See the pinnedRepos docstring
+ * for the full contract.
+ *
+ * Returns a `release` disposer (mirroring addPoolCloseListener) that releases
+ * THIS lease exactly once — calling it twice is a no-op, so it can never
+ * over-decrement a sibling holder's count. Prefer the disposer
+ * (`const release = pinRepo(id); try { … } finally { release(); }`) so the
+ * pin/release pair is leak-proof; unpinRepo remains available for callers that
+ * pair explicitly.
+ */
+export const pinRepo = (repoId: string): (() => void) => {
+  pinnedRepos.set(repoId, (pinnedRepos.get(repoId) ?? 0) + 1);
+  let released = false;
+  return () => {
+    if (released) return;
+    released = true;
+    unpinRepo(repoId);
+  };
+};
+
+/**
+ * Release one eviction-exemption lease on a repo. The repo becomes eligible for
+ * automatic eviction again only once its count reaches 0 (the key is deleted).
+ * Idempotent at the floor: releasing a repo with no active lease is a no-op (no
+ * negative counts). Does NOT close the repo's pool.
+ */
+export const unpinRepo = (repoId: string): void => {
+  const count = pinnedRepos.get(repoId);
+  if (count === undefined) return;
+  if (count <= 1) {
+    pinnedRepos.delete(repoId);
+  } else {
+    pinnedRepos.set(repoId, count - 1);
+  }
+};
+
+/**
+ * Maximum number of repos a bounded multi-repo operation (e.g. group sync's
+ * windowed manifest resolution) should hold resident at once. Equals
+ * MAX_POOL_SIZE today, but exposed under an intent-named accessor so callers
+ * size their working set against "max repos a bounded op should hold" rather
+ * than coupling to the LRU eviction-cap constant, which may be tuned
+ * independently.
+ */
+export const getMaxResidentRepos = (): number => MAX_POOL_SIZE;
+
+/**
+ * Evict the least-recently-used repo if pool is at capacity.
+ * Pinned repos are never chosen as the eviction victim — when every eligible
+ * entry is pinned, no eviction occurs and the pool transiently exceeds
+ * MAX_POOL_SIZE (see the pinnedRepos docstring).
  */
 function evictLRU(): void {
   if (pool.size < MAX_POOL_SIZE) return;
@@ -175,6 +258,7 @@ function evictLRU(): void {
   let oldestId: string | null = null;
   let oldestTime = Infinity;
   for (const [id, entry] of pool) {
+    if (pinnedRepos.has(id)) continue;
     if (entry.checkedOut === 0 && entry.lastUsed < oldestTime) {
       oldestTime = entry.lastUsed;
       oldestId = id;
@@ -244,6 +328,11 @@ function closeOne(repoId: string): void {
 
   pool.delete(repoId);
 
+  // Clear any eviction pin — the entry is gone, so the pin is meaningless and
+  // would otherwise leak across operations in a long-lived process. Teardown
+  // is authoritative: an explicit close always wins over a pin.
+  pinnedRepos.delete(repoId);
+
   // Notify listeners AFTER the pool entry is gone so any cache-invalidation
   // they perform is consistent with `isLbugReady(repoId) === false`.
   for (const listener of poolCloseListeners) {
diff --git a/gitnexus/test/unit/group/sync-windowed-resolution.test.ts b/gitnexus/test/unit/group/sync-windowed-resolution.test.ts
new file mode 100644
index 000000000..d7cdb4090
--- /dev/null
+++ b/gitnexus/test/unit/group/sync-windowed-resolution.test.ts
@@ -0,0 +1,243 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import * as os from 'node:os';
+import * as path from 'node:path';
+import { mkdtempSync, writeFileSync, mkdirSync, rmSync } from 'node:fs';
+import type { GroupConfig, GroupManifestLink } from '../../../src/core/group/types.js';
+
+// Two test surfaces for the windowed manifest resolution (issue #2189 / PR #2191
+// review, Finding 3 — bound peak pool residency to MAX_POOL_SIZE regardless of
+// group size):
+//
+//   1. partitionManifestWindows — a pure function; the bounded-residency logic
+//      lives here (every window references <= maxResident repos, every link in
+//      exactly one window). Tested directly, no pool.
+//   2. A real-pool integration test that drives syncGroup through the actual
+//      pool (native LadybugDB layer mocked, as in lbug-pool-pinning.test.ts) and
+//      asserts the count of concurrently-open Databases never exceeds the
+//      resident cap — the end-to-end residency bound the review flagged as
+//      missing.
+
+// ── Surface 1: pure partition function ──────────────────────────────────────
+
+describe('partitionManifestWindows (issue #2189 windowed resolution)', () => {
+  const link = (from: string, to: string): GroupManifestLink => ({
+    from,
+    to,
+    type: 'http',
+    contract: `GET::/${from}-${to}`,
+    role: 'consumer',
+  });
+
+  it('keeps every window within maxResident repos and places every link exactly once', async () => {
+    const { partitionManifestWindows } = await import('../../../src/core/group/sync.js');
+    const repos = ['r1', 'r2', 'r3', 'r4', 'r5', 'r6', 'r7', 'r8'];
+    const known = new Set(repos);
+    // A star: every leaf links to the hub r1, plus a few leaf-leaf links.
+    const links = [
+      link('r1', 'r2'),
+      link('r1', 'r3'),
+      link('r1', 'r4'),
+      link('r1', 'r5'),
+      link('r1', 'r6'),
+      link('r7', 'r8'),
+      link('r2', 'r3'),
+    ];
+    const maxResident = 5;
+    const windows = partitionManifestWindows(links, known, maxResident);
+
+    // Bounded residency: no window references more than maxResident repos.
+    for (const w of windows) expect(w.repos.size).toBeLessThanOrEqual(maxResident);
+
+    // True partition: every link appears in exactly one window.
+    const placed = windows.flatMap((w) => w.links);
+    expect(placed).toHaveLength(links.length);
+    const placedKeys = placed.map((l) => `${l.from}->${l.to}`).sort();
+    const inputKeys = links.map((l) => `${l.from}->${l.to}`).sort();
+    expect(placedKeys).toEqual(inputKeys);
+    // No link appears twice (the contract-dedup invariant — KTD-4).
+    expect(new Set(placedKeys).size).toBe(placedKeys.length);
+  });
+
+  it('counts only in-group repos toward a window; dangling links consume no budget', async () => {
+    const { partitionManifestWindows } = await import('../../../src/core/group/sync.js');
+    const known = new Set(['r1']);
+    const links = [
+      link('r1', 'external-a'), // 1 in-group repo
+      link('external-b', 'external-c'), // 0 in-group repos (fully dangling)
+    ];
+    const windows = partitionManifestWindows(links, known, 5);
+    // Both links are still placed (so they yield synthetic-UID contracts)...
+    expect(windows.flatMap((w) => w.links)).toHaveLength(2);
+    // ...but the only repo counted is r1.
+    const allRepos = new Set(windows.flatMap((w) => [...w.repos]));
+    expect(allRepos).toEqual(new Set(['r1']));
+  });
+
+  it('returns no windows for an empty link set', async () => {
+    const { partitionManifestWindows } = await import('../../../src/core/group/sync.js');
+    expect(partitionManifestWindows([], new Set(['r1']), 5)).toEqual([]);
+  });
+
+  it('splits links across multiple windows when referenced repos exceed maxResident', async () => {
+    const { partitionManifestWindows } = await import('../../../src/core/group/sync.js');
+    const known = new Set(['r1', 'r2', 'r3', 'r4', 'r5', 'r6']);
+    // 3 disjoint repo-pairs = 6 distinct repos; maxResident 2 forces ≥3 windows.
+    const links = [link('r1', 'r2'), link('r3', 'r4'), link('r5', 'r6')];
+    const windows = partitionManifestWindows(links, known, 2);
+    expect(windows.length).toBeGreaterThanOrEqual(3);
+    for (const w of windows) expect(w.repos.size).toBeLessThanOrEqual(2);
+    expect(windows.flatMap((w) => w.links)).toHaveLength(3);
+  });
+});
+
+// ── Surface 2: real-pool residency bound through syncGroup ───────────────────
+
+const { loadFTSExtensionMock, openCounter } = vi.hoisted(() => ({
+  loadFTSExtensionMock: vi.fn(),
+  openCounter: { live: 0, peak: 0 },
+}));
+
+vi.mock('@ladybugdb/core', () => ({
+  default: {
+    Database: vi.fn(),
+    Connection: vi.fn(function (this: any) {
+      this.query = vi.fn().mockResolvedValue({
+        getAll: vi.fn().mockResolvedValue([]),
+        close: vi.fn(),
+      });
+      // executeParameterized's prepare/execute path (manifest resolveSymbol).
+      this.prepare = vi.fn().mockResolvedValue({
+        isSuccess: () => true,
+        getErrorMessage: vi.fn().mockResolvedValue(''),
+      });
+      this.execute = vi.fn().mockResolvedValue({
+        getAll: vi.fn().mockResolvedValue([]),
+        close: vi.fn(),
+      });
+      this.close = vi.fn().mockResolvedValue(undefined);
+    }),
+  },
+}));
+
+vi.mock('../../../src/core/lbug/lbug-adapter.js', () => ({
+  isReadOnlyDbError: vi.fn(() => false),
+  loadFTSExtension: loadFTSExtensionMock,
+}));
+
+vi.mock('../../../src/core/lbug/lbug-config.js', () => ({
+  // Track concurrently-open Databases: a fresh fake per open, decrement on close.
+  createLbugDatabase: vi.fn(() => {
+    openCounter.live += 1;
+    openCounter.peak = Math.max(openCounter.peak, openCounter.live);
+    return {
+      init: vi.fn().mockResolvedValue(undefined),
+      close: vi.fn().mockImplementation(async () => {
+        openCounter.live -= 1;
+      }),
+    };
+  }),
+  toNativeSafePath: vi.fn((p: string) => p),
+  isWalCorruptionError: vi.fn(() => false),
+  WAL_RECOVERY_SUGGESTION: '',
+}));
+
+vi.mock('../../../src/core/lbug/sidecar-recovery.js', () => ({
+  preflightLbugSidecars: vi.fn().mockResolvedValue(undefined),
+  isMissingFsError: vi.fn(() => false),
+  isMissingShadowSidecarError: vi.fn(() => false),
+  isReadOnlyShadowReplayError: vi.fn(() => false),
+  quarantineWalForMissingShadow: vi.fn().mockResolvedValue(''),
+  renameFailureMessage: vi.fn((p: string) => `rename failed for ${p}`),
+  statIfExists: vi.fn().mockResolvedValue(null),
+}));
+
+// readRegistry is called in syncGroup's else branch; resolveRepoHandle is
+// supplied, so an empty registry is fine (only the meta.json fallback reads it).
+vi.mock('../../../src/storage/repo-manager.js', () => ({
+  readRegistry: vi.fn().mockResolvedValue([]),
+}));
+
+const { syncGroup } = await import('../../../src/core/group/sync.js');
+const { closeLbug, getMaxResidentRepos } = await import('../../../src/core/lbug/pool-adapter.js');
+
+describe('syncGroup windowed resolution bounds pool residency (real pool, #2189)', () => {
+  let tmpRoot: string;
+
+  beforeEach(() => {
+    tmpRoot = mkdtempSync(path.join(os.tmpdir(), 'gn-window-resid-'));
+    loadFTSExtensionMock.mockResolvedValue(true);
+    openCounter.live = 0;
+    openCounter.peak = 0;
+  });
+
+  afterEach(async () => {
+    await closeLbug().catch(() => {});
+    rmSync(tmpRoot, { recursive: true, force: true });
+  });
+
+  it('never holds more than getMaxResidentRepos() Databases open for a large group', async () => {
+    const maxResident = getMaxResidentRepos();
+    const repoCount = maxResident + 4; // exceed the cap so windowing must split
+
+    const repos: Record<string, string> = {};
+    const links: GroupManifestLink[] = [];
+    for (let i = 1; i <= repoCount; i++) {
+      const gp = `app/repo-${i}`;
+      repos[gp] = `repo-${i}`;
+      // Star topology: every repo links to repo-1 → many windows reference repo-1.
+      if (i > 1) {
+        links.push({
+          from: gp,
+          to: 'app/repo-1',
+          type: 'http',
+          contract: `GET::/api/${i}`,
+          role: 'consumer',
+        });
+      }
+    }
+
+    const config: GroupConfig = {
+      version: 1,
+      name: 'test',
+      description: '',
+      repos,
+      links,
+      packages: {},
+      // All detection off → init loop just opens pools (no extractor file reads).
+      detect: {
+        http: false,
+        grpc: false,
+        thrift: false,
+        topics: false,
+        shared_libs: false,
+        embedding_fallback: false,
+        workspace_deps: false,
+      },
+      matching: { bm25_threshold: 0.7, embedding_threshold: 0.65, max_candidates_per_step: 3 },
+    };
+
+    await syncGroup(config, {
+      resolveRepoHandle: async (_name, groupPath) => {
+        // Each repo gets a real storage dir with a fake lbug file so fs.stat in
+        // doInitLbug succeeds; distinct paths → distinct Databases.
+        const storagePath = path.join(tmpRoot, groupPath);
+        mkdirSync(storagePath, { recursive: true });
+        writeFileSync(path.join(storagePath, 'lbug'), '');
+        return {
+          id: groupPath.replace(/\//g, '-'),
+          path: groupPath,
+          repoPath: storagePath,
+          storagePath,
+        };
+      },
+      skipWrite: true,
+    });
+
+    // The init loop (no pin) keeps the pool at the LRU cap; windowed resolution
+    // leases <= maxResident repos per window and releases them. Peak concurrent
+    // open Databases must stay within the resident cap (+ at most one transient
+    // overshoot at an init boundary — the pool's documented soft cap).
+    expect(openCounter.peak).toBeGreaterThan(0);
+    expect(openCounter.peak).toBeLessThanOrEqual(maxResident + 1);
+  });
+});
diff --git a/gitnexus/test/unit/group/sync.test.ts b/gitnexus/test/unit/group/sync.test.ts
index 4fc320076..061f5cfc4 100644
--- a/gitnexus/test/unit/group/sync.test.ts
+++ b/gitnexus/test/unit/group/sync.test.ts
@@ -166,20 +166,19 @@ describe('syncGroup', () => {
     expect(result).toBeDefined();
   });
 
-  it('test_syncGroup_closes_only_opened_pools', async () => {
+  it('test_syncGroup_does_not_force_close_pools (release-not-close, #2191 review)', async () => {
+    // Post windowed-resolution refactor, syncGroup releases its eviction leases
+    // and lets the pool's LRU reclaim repos — it does NOT call closeLbug. This
+    // avoids tearing down a pool entry a concurrent MCP reader may share.
     const config = makeConfig({
       'app/backend': 'backend-repo',
       'app/frontend': 'frontend-repo',
     });
 
-    const closedIds: string[] = [];
-
     const { vi } = await import('vitest');
     const poolAdapter = await import('../../../src/core/lbug/pool-adapter.js');
     const initSpy = vi.spyOn(poolAdapter, 'initLbug').mockResolvedValue(undefined);
-    const closeSpy = vi.spyOn(poolAdapter, 'closeLbug').mockImplementation(async (id?: string) => {
-      if (id) closedIds.push(id);
-    });
+    const closeSpy = vi.spyOn(poolAdapter, 'closeLbug').mockResolvedValue(undefined);
 
     try {
       await syncGroup(config, {
@@ -192,19 +191,8 @@ describe('syncGroup', () => {
         skipWrite: true,
       }).catch(() => {});
 
-      // closeLbug must have been called at least once with specific pool ids
-      expect(closeSpy.mock.calls.length).toBeGreaterThan(0);
-      expect(closedIds).toContain('app-backend');
-      expect(closedIds).toContain('app-frontend');
-
-      // Every call must have a truthy string id
-      for (const id of closedIds) {
-        expect(id).toBeTruthy();
-        expect(typeof id).toBe('string');
-      }
-      // No blanket close (no-arg or empty-string or undefined)
-      const blanketCalls = closeSpy.mock.calls.filter((args) => args.length === 0 || !args[0]);
-      expect(blanketCalls).toHaveLength(0);
+      // No closeLbug — repos are left evictable for the LRU to reclaim.
+      expect(closeSpy.mock.calls.length).toBe(0);
     } finally {
       initSpy.mockRestore();
       closeSpy.mockRestore();
@@ -534,7 +522,9 @@ service OrderService {
         },
       });
       expect(initSpy).toHaveBeenCalledWith('billing-repo', path.join(storageDir, 'lbug'));
-      expect(closeSpy).toHaveBeenCalledWith('billing-repo');
+      // syncGroup no longer force-closes pools (release-not-close, #2191 review);
+      // repos are left evictable for the LRU. Assert no teardown call here.
+      expect(closeSpy).not.toHaveBeenCalled();
     } finally {
       initSpy.mockRestore();
       closeSpy.mockRestore();
@@ -1044,18 +1034,20 @@ service OrderService {
         skipWrite: true,
       });
 
-      // Manifest symbol resolution must run while pools are still open
+      // Manifest symbol resolution runs against live (leased) pools.
       expect(manifestResolvedWhilePoolOpen).toBe(true);
-      expect(closeLbugCalled).toBe(true);
 
       // The manifest cross-link must use the real UID from the DB, not synthetic
+      // — the #2189 fix, now via windowed resolution (the svc/orders↔svc/payments
+      // link forms one window whose repos are re-inited + leased for resolution).
       const manifestLinks = result.crossLinks.filter((cl) => cl.matchType === 'manifest');
       expect(manifestLinks).toHaveLength(1);
       expect(manifestLinks[0].to.symbolUid).toBe('real-uid-checkout');
       expect(manifestLinks[0].to.symbolUid).not.toContain('manifest::');
 
-      // closeLbug must fire exactly twice (one per repo)
-      expect(closeSpy).toHaveBeenCalledTimes(2);
+      // syncGroup no longer force-closes pools (release-not-close, #2191 review).
+      expect(closeLbugCalled).toBe(false);
+      expect(closeSpy).not.toHaveBeenCalled();
     } finally {
       initSpy.mockRestore();
       closeSpy.mockRestore();
@@ -1105,6 +1097,198 @@ service OrderService {
   });
 });
 
+// Lifecycle wiring for issue #2189: syncGroup must pin every repo it
+// initializes (so a group larger than MAX_POOL_SIZE survives deferred
+// manifest/workspace resolution) and release those pins on completion AND on
+// error. The eviction-survival MECHANISM itself is proven against real
+// evictLRU in test/unit/lbug-pool-pinning.test.ts; these tests prove the sync
+// loop drives that mechanism correctly. (A full end-to-end proof through the
+// real pool — real symbolUid instead of synthetic after >5 repos — would
+// require a real or fully-native-mocked LadybugDB stack; mechanism + wiring
+// coverage stands in for it here.)
+describe('syncGroup windowed manifest resolution (issue #2189 / PR #2191 review)', () => {
+  const groupConfig = (count: number, links: GroupManifestLink[] = []): GroupConfig => {
+    const repos: Record<string, string> = {};
+    for (let i = 1; i <= count; i++) repos[`app/repo-${i}`] = `repo-${i}`;
+    return {
+      version: 1,
+      name: 'test',
+      description: '',
+      repos,
+      links,
+      packages: {},
+      detect: {
+        http: true,
+        grpc: false,
+        thrift: false,
+        topics: false,
+        shared_libs: false,
+        embedding_fallback: false,
+        workspace_deps: false,
+      },
+      matching: { bm25_threshold: 0.7, embedding_threshold: 0.65, max_candidates_per_step: 3 },
+    };
+  };
+
+  const okHandle = async (_name: string, groupPath: string): Promise<RepoHandle> => ({
+    id: groupPath.replace(/\//g, '-'),
+    path: groupPath,
+    repoPath: '/tmp/' + groupPath,
+    storagePath: '/tmp/' + groupPath + '/.gitnexus',
+  });
+
+  const httpLink = (from: string, to: string): GroupManifestLink => ({
+    from,
+    to,
+    type: 'http',
+    contract: 'GET::/api/x',
+    role: 'consumer',
+  });
+
+  // pinRepo now returns a release disposer; the spy returns a tracked spy fn so
+  // tests can assert every acquired lease was released.
+  const setupPoolSpies = async () => {
+    const poolAdapter = await import('../../../src/core/lbug/pool-adapter.js');
+    const releaseSpies: Array<ReturnType<typeof vi.fn>> = [];
+    const initSpy = vi.spyOn(poolAdapter, 'initLbug').mockResolvedValue(undefined);
+    const execSpy = vi.spyOn(poolAdapter, 'executeParameterized').mockResolvedValue([]);
+    const pinSpy = vi.spyOn(poolAdapter, 'pinRepo').mockImplementation(() => {
+      const release = vi.fn();
+      releaseSpies.push(release);
+      return release;
+    });
+    const restore = () => {
+      initSpy.mockRestore();
+      execSpy.mockRestore();
+      pinSpy.mockRestore();
+    };
+    return { releaseSpies, initSpy, execSpy, pinSpy, restore };
+  };
+
+  it('pins only the repos referenced by manifest links, not the whole group', async () => {
+    const { pinSpy, restore } = await setupPoolSpies();
+    try {
+      await syncGroup(groupConfig(8, [httpLink('app/repo-1', 'app/repo-2')]), {
+        resolveRepoHandle: okHandle,
+        skipWrite: true,
+      });
+      const pinnedIds = pinSpy.mock.calls.map((c) => c[0]).sort();
+      // Only the windowed (link-referenced) repos are leased — bounded residency,
+      // not the whole 8-repo group.
+      expect(pinnedIds).toEqual(['app-repo-1', 'app-repo-2']);
+      expect(pinnedIds).not.toContain('app-repo-3');
+    } finally {
+      restore();
+    }
+  });
+
+  it('does not pin during the init loop when there are no manifest links', async () => {
+    const { pinSpy, restore } = await setupPoolSpies();
+    try {
+      await syncGroup(groupConfig(8, []), { resolveRepoHandle: okHandle, skipWrite: true });
+      // The init loop extracts contracts without pinning; with no links there
+      // are no resolution windows, so nothing is ever pinned.
+      expect(pinSpy.mock.calls.length).toBe(0);
+    } finally {
+      restore();
+    }
+  });
+
+  it('releases every window lease on successful completion', async () => {
+    const { releaseSpies, restore } = await setupPoolSpies();
+    try {
+      await syncGroup(
+        groupConfig(8, [
+          httpLink('app/repo-1', 'app/repo-2'),
+          httpLink('app/repo-7', 'app/repo-8'),
+        ]),
+        { resolveRepoHandle: okHandle, skipWrite: true },
+      );
+      expect(releaseSpies.length).toBeGreaterThan(0);
+      for (const release of releaseSpies) expect(release).toHaveBeenCalled();
+    } finally {
+      restore();
+    }
+  });
+
+  it('releases the window leases even when resolution throws mid-window', async () => {
+    const { ManifestExtractor } =
+      await import('../../../src/core/group/extractors/manifest-extractor.js');
+    const { releaseSpies, restore } = await setupPoolSpies();
+    const manifestSpy = vi
+      .spyOn(ManifestExtractor.prototype, 'extractFromManifest')
+      .mockRejectedValue(new Error('resolution boom'));
+    try {
+      await expect(
+        syncGroup(groupConfig(8, [httpLink('app/repo-1', 'app/repo-2')]), {
+          resolveRepoHandle: okHandle,
+          skipWrite: true,
+        }),
+      ).rejects.toThrow('resolution boom');
+      // The window's finally released its acquired leases despite the throw.
+      expect(releaseSpies.length).toBeGreaterThan(0);
+      for (const release of releaseSpies) expect(release).toHaveBeenCalled();
+    } finally {
+      restore();
+      manifestSpy.mockRestore();
+    }
+  });
+
+  it('does not pin a repo that fails to resolve (no pool handle)', async () => {
+    const { pinSpy, restore } = await setupPoolSpies();
+    try {
+      await syncGroup(groupConfig(3, [httpLink('app/repo-1', 'app/repo-2')]), {
+        resolveRepoHandle: async (_name, groupPath) =>
+          groupPath === 'app/repo-2' ? null : okHandle(_name, groupPath),
+        skipWrite: true,
+      });
+      const pinnedIds = pinSpy.mock.calls.map((c) => c[0]);
+      // repo-2 has no handle (resolve returned null) → not in knownRepos →
+      // never windowed, never leased; repo-1 (resolved) is.
+      expect(pinnedIds).toContain('app-repo-1');
+      expect(pinnedIds).not.toContain('app-repo-2');
+    } finally {
+      restore();
+    }
+  });
+
+  it('releases an already-acquired lease when a later init in the same window throws', async () => {
+    const poolAdapter = await import('../../../src/core/lbug/pool-adapter.js');
+    const releaseSpies: Array<ReturnType<typeof vi.fn>> = [];
+    // Throw on the SECOND init of app-repo-2 — the first is the init-loop
+    // extraction; the second is the window re-init. This isolates the failure
+    // to window setup, after app-repo-1's lease was already acquired.
+    const initCounts = new Map<string, number>();
+    const initSpy = vi.spyOn(poolAdapter, 'initLbug').mockImplementation(async (id: string) => {
+      const n = (initCounts.get(id) ?? 0) + 1;
+      initCounts.set(id, n);
+      if (id === 'app-repo-2' && n === 2) throw new Error('window init boom');
+    });
+    const execSpy = vi.spyOn(poolAdapter, 'executeParameterized').mockResolvedValue([]);
+    const pinSpy = vi.spyOn(poolAdapter, 'pinRepo').mockImplementation(() => {
+      const release = vi.fn();
+      releaseSpies.push(release);
+      return release;
+    });
+    try {
+      await expect(
+        syncGroup(groupConfig(2, [httpLink('app/repo-1', 'app/repo-2')]), {
+          resolveRepoHandle: okHandle,
+          skipWrite: true,
+        }),
+      ).rejects.toThrow('window init boom');
+      // Exactly one lease was acquired (app-repo-1) before app-repo-2's init
+      // threw, and the window finally released it — no leaked lease.
+      expect(releaseSpies.length).toBe(1);
+      expect(releaseSpies[0]).toHaveBeenCalled();
+    } finally {
+      initSpy.mockRestore();
+      execSpy.mockRestore();
+      pinSpy.mockRestore();
+    }
+  });
+});
+
 describe('stableRepoPoolId', () => {
   it('returns lowercase name when no collision', () => {
     const entry: RegistryEntry = {
diff --git a/gitnexus/test/unit/lbug-pool-pinning.test.ts b/gitnexus/test/unit/lbug-pool-pinning.test.ts
new file mode 100644
index 000000000..914647b09
--- /dev/null
+++ b/gitnexus/test/unit/lbug-pool-pinning.test.ts
@@ -0,0 +1,223 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import * as os from 'node:os';
+import * as path from 'node:path';
+import { mkdtempSync, writeFileSync, rmSync } from 'node:fs';
+
+// Drive the REAL initLbug path (which calls evictLRU) rather than
+// initLbugWithDb (which bypasses eviction entirely). The native LadybugDB
+// open/connect/FTS stack is mocked exactly as in lbug-pool-fts-load.test.ts,
+// plus sidecar-recovery so openReadOnlyDatabase's preflight is a no-op. fs is
+// NOT mocked — each repo uses a real temp file so the fs.stat existence check
+// in doInitLbug succeeds naturally.
+//
+// Covers issue #2189: a group sync larger than MAX_POOL_SIZE must keep every
+// repo resident through deferred manifest/workspace resolution. Pinning makes
+// that resident set survive automatic (LRU + idle) eviction.
+
+const { loadFTSExtensionMock } = vi.hoisted(() => ({
+  loadFTSExtensionMock: vi.fn(),
+}));
+
+vi.mock('@ladybugdb/core', () => ({
+  default: {
+    Database: vi.fn(),
+    Connection: vi.fn(function (this: any) {
+      // probeDatabaseForShadowReplay() runs a probe query during the
+      // read-only open; the result must expose getAll()/close().
+      this.query = vi.fn().mockResolvedValue({
+        getAll: vi.fn().mockResolvedValue([]),
+        close: vi.fn(),
+      });
+      this.close = vi.fn().mockResolvedValue(undefined);
+    }),
+  },
+}));
+
+vi.mock('../../src/core/lbug/lbug-adapter.js', () => ({
+  isReadOnlyDbError: vi.fn(() => false),
+  loadFTSExtension: loadFTSExtensionMock,
+}));
+
+vi.mock('../../src/core/lbug/lbug-config.js', () => ({
+  // A fresh fake Database per call so distinct dbPaths get distinct entries
+  // and closeOne's db.close() resolves per repo.
+  createLbugDatabase: vi.fn(() => ({
+    init: vi.fn().mockResolvedValue(undefined),
+    close: vi.fn().mockResolvedValue(undefined),
+  })),
+  toNativeSafePath: vi.fn((p: string) => p),
+  isWalCorruptionError: vi.fn(() => false),
+  WAL_RECOVERY_SUGGESTION: '',
+}));
+
+vi.mock('../../src/core/lbug/sidecar-recovery.js', () => ({
+  preflightLbugSidecars: vi.fn().mockResolvedValue(undefined),
+  isMissingFsError: vi.fn(() => false),
+  isMissingShadowSidecarError: vi.fn(() => false),
+  isReadOnlyShadowReplayError: vi.fn(() => false),
+  quarantineWalForMissingShadow: vi.fn().mockResolvedValue(''),
+  renameFailureMessage: vi.fn((p: string) => `rename failed for ${p}`),
+  statIfExists: vi.fn().mockResolvedValue(null),
+}));
+
+const { initLbug, closeLbug, isLbugReady, pinRepo, unpinRepo } =
+  await import('../../src/core/lbug/pool-adapter.js');
+
+describe('pool-adapter repo pinning (issue #2189)', () => {
+  let tmpDir: string;
+  // Track every repoId touched so afterEach can fully reset module-global state.
+  const touched = new Set<string>();
+
+  const dbPathFor = (repoId: string): string => {
+    const p = path.join(tmpDir, `${repoId}.lbug`);
+    writeFileSync(p, ''); // real file so fs.stat() in doInitLbug succeeds
+    return p;
+  };
+
+  const init = async (repoId: string): Promise<void> => {
+    touched.add(repoId);
+    await initLbug(repoId, dbPathFor(repoId));
+  };
+
+  beforeEach(() => {
+    tmpDir = mkdtempSync(path.join(os.tmpdir(), 'gn-pin-test-'));
+    loadFTSExtensionMock.mockResolvedValue(true);
+  });
+
+  afterEach(async () => {
+    vi.useRealTimers();
+    await closeLbug().catch(() => {});
+    for (const id of touched) unpinRepo(id);
+    touched.clear();
+    loadFTSExtensionMock.mockReset();
+    rmSync(tmpDir, { recursive: true, force: true });
+  });
+
+  // MAX_POOL_SIZE is 5; the 6th init triggers evictLRU.
+  it('characterization: WITHOUT pinning, the earliest repo is LRU-evicted past the cap', async () => {
+    for (let i = 1; i <= 6; i++) await init(`repo-${i}`);
+
+    // repo-1 had the oldest lastUsed and nothing was checked out, so it is the
+    // eviction victim — exactly the stale-executor scenario from #2189.
+    expect(isLbugReady('repo-1')).toBe(false);
+    // The most recently initialized repo survives.
+    expect(isLbugReady('repo-6')).toBe(true);
+  });
+
+  it('FIX: pinning each repo keeps all of them resident past the cap', async () => {
+    for (let i = 1; i <= 6; i++) {
+      await init(`repo-${i}`);
+      pinRepo(`repo-${i}`);
+    }
+
+    for (let i = 1; i <= 6; i++) {
+      expect(isLbugReady(`repo-${i}`)).toBe(true);
+    }
+  });
+
+  it('explicit close beats the pin AND clears it (no cross-operation leak)', async () => {
+    pinRepo('repo-x');
+    await init('repo-x');
+    expect(isLbugReady('repo-x')).toBe(true);
+
+    // Explicit teardown closes a pinned repo without needing an unpin first.
+    await closeLbug('repo-x');
+    expect(isLbugReady('repo-x')).toBe(false);
+
+    // The pin must have been cleared on close: re-init repo-x FIRST (oldest
+    // lastUsed) and fill past the cap. If the pin had leaked, repo-x would be
+    // un-evictable; instead it is evicted as the LRU victim.
+    await init('repo-x');
+    for (let i = 1; i <= 5; i++) await init(`fresh-${i}`);
+    expect(isLbugReady('repo-x')).toBe(false);
+  });
+
+  it('idle-timeout sweep skips pinned repos but still evicts idle unpinned ones', async () => {
+    vi.useFakeTimers();
+
+    await init('pinned-idle');
+    pinRepo('pinned-idle');
+    await init('unpinned-idle');
+
+    expect(isLbugReady('pinned-idle')).toBe(true);
+    expect(isLbugReady('unpinned-idle')).toBe(true);
+
+    // The idle timer runs every 60s and closes entries idle past
+    // IDLE_TIMEOUT_MS (5 min) with no checked-out connections. advance past
+    // both thresholds, flushing microtasks between fires.
+    await vi.advanceTimersByTimeAsync(5 * 60 * 1000 + 60 * 1000);
+
+    expect(isLbugReady('pinned-idle')).toBe(true);
+    expect(isLbugReady('unpinned-idle')).toBe(false);
+  });
+
+  it('unpinRepo re-enables eviction for that repo', async () => {
+    // Pin five repos and fill the pool; a sixth init evicts nothing (all pinned).
+    for (let i = 1; i <= 5; i++) {
+      await init(`p-${i}`);
+      pinRepo(`p-${i}`);
+    }
+    await init('p-6'); // unpinned; pool now holds 6 (soft-cap exceeded)
+    for (let i = 1; i <= 6; i++) expect(isLbugReady(`p-${i}`)).toBe(true);
+
+    // Unpin the oldest, then init a 7th repo — the now-unpinned p-1 is the LRU
+    // victim.
+    unpinRepo('p-1');
+    await init('p-7');
+    expect(isLbugReady('p-1')).toBe(false);
+    expect(isLbugReady('p-7')).toBe(true);
+  });
+
+  it('reference-counts leases: two pins need two unpins before eviction (Finding 1)', async () => {
+    // Fill the pool to capacity, all leased.
+    for (let i = 1; i <= 4; i++) {
+      await init(`rc-${i}`);
+      pinRepo(`rc-${i}`);
+    }
+    await init('rc-shared');
+    pinRepo('rc-shared'); // lease 1
+    pinRepo('rc-shared'); // lease 2 (two holders)
+
+    // Release ONE lease — a holder remains, so rc-shared stays exempt even
+    // under eviction pressure.
+    unpinRepo('rc-shared');
+    await init('rc-extra'); // evictLRU finds no unpinned victim → pool grows
+    expect(isLbugReady('rc-shared')).toBe(true);
+
+    // Release the LAST lease — now rc-shared (oldest unpinned) is evictable.
+    unpinRepo('rc-shared');
+    await init('rc-extra2');
+    expect(isLbugReady('rc-shared')).toBe(false);
+  });
+
+  it('unpinRepo floors at zero and tolerates unknown repoIds', () => {
+    expect(() => {
+      unpinRepo('never-touched'); // unknown repoId → no-op
+      pinRepo('floor-x');
+      unpinRepo('floor-x'); // count 0 → key deleted
+      unpinRepo('floor-x'); // already gone → no-op, never a negative count
+    }).not.toThrow();
+  });
+
+  it('pinRepo returns a disposer that releases exactly once and composes with refcount', async () => {
+    for (let i = 1; i <= 4; i++) {
+      await init(`d-${i}`);
+      pinRepo(`d-${i}`);
+    }
+    await init('d-shared');
+    const release1 = pinRepo('d-shared'); // lease 1
+    const release2 = pinRepo('d-shared'); // lease 2
+
+    release1();
+    release1(); // double-call is a no-op — must NOT decrement lease 2
+
+    // lease 2 still held → d-shared survives eviction pressure.
+    await init('d-extra');
+    expect(isLbugReady('d-shared')).toBe(true);
+
+    // Release the last lease via its own disposer → now evictable.
+    release2();
+    await init('d-extra2');
+    expect(isLbugReady('d-shared')).toBe(false);
+  });
+});