feat(us-016): tracker route for HF models, endpoint dedup, purge logging

Tracker /v1/route now resolves HF model nodes (by hf_repo or short name)
in addition to preset models, using the same greedy interval-cover logic.
This allows distributed inference routing across two nodes each holding
half the model.

Endpoint dedup: re-registering the same endpoint atomically replaces the
old entry so stale registrations don't accumulate across node restarts.

Purge logging: tracker now prints when a node expires due to missed
heartbeats so operators can see dead nodes being removed.

Timing fix: heartbeat timeout raised from 30s to 90s (3 missed beats);
node heartbeat interval lowered from 30s to 20s to maintain margin.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/node/meshnet_node/startup.py

@@ -5,6 +5,8 @@ from __future__ import annotations
 import json
 import socket
 import sys
+import threading
+import time
 import urllib.error
 import urllib.parse
 import urllib.request
@@ -32,6 +34,23 @@ def _get_json(url: str, timeout: float = 10.0) -> dict:
         return json.loads(r.read())
 
 
+def _start_heartbeat(tracker_url: str, node_id: str, interval: float = 20.0) -> threading.Thread:
+    """Daemon thread that sends periodic heartbeats to the tracker."""
+    def _loop() -> None:
+        hb_url = f"{tracker_url}/v1/nodes/{node_id}/heartbeat"
+        while True:
+            time.sleep(interval)
+            try:
+                _post_json(hb_url, {})
+                print(f"  [node] heartbeat sent → tracker (node {node_id[:8]})", flush=True)
+            except Exception as exc:
+                print(f"  [node] WARNING: heartbeat failed: {exc}", flush=True)
+
+    t = threading.Thread(target=_loop, daemon=True, name="heartbeat")
+    t.start()
+    return t
+
+
 def run_startup(
     tracker_url: str,
     port: int = 0,
@@ -84,7 +103,7 @@ def run_startup(
     if probationary_line is not None:
         print(f"  {probationary_line}", flush=True)
 
-    if model_id is not None:
+    if model_id:  # treat "" the same as None — no explicit model given
         # Auto-detect shard range from model config if not explicitly provided
         if shard_start is None or shard_end is None:
             detected = _detect_num_layers(model_id)
@@ -93,6 +112,23 @@ def run_startup(
                     f"Could not read num_hidden_layers from {model_id} config. "
                     "Pass --shard-start and --shard-end explicitly."
                 )
+            # When no explicit shard range given, ask the tracker if there's a gap for this model.
+            if shard_start is None and shard_end is None:
+                try:
+                    qs = urllib.parse.urlencode({
+                        "device": device, "vram_mb": vram_mb, "hf_repo": model_id,
+                    })
+                    net_asgn = _get_json(f"{tracker_url}/v1/network/assign?{qs}", timeout=5.0)
+                    if net_asgn.get("hf_repo") == model_id and net_asgn.get("gap_found"):
+                        shard_start = net_asgn["shard_start"]
+                        shard_end = net_asgn["shard_end"]
+                        print(
+                            f"  Tracker found uncovered shard: "
+                            f"layers {shard_start}–{shard_end} (of {detected})",
+                            flush=True,
+                        )
+                except Exception:
+                    pass  # No other nodes registered yet — default to full model below
             shard_start = shard_start if shard_start is not None else 0
             shard_end = shard_end if shard_end is not None else detected - 1
             print(f"  Auto-detected {detected} layers → shard {shard_start}–{shard_end}", flush=True)
@@ -116,6 +152,31 @@ def run_startup(
             shard_label = f"layers {shard_start}–{shard_end}"
         public_host = advertise_host or (socket.getfqdn() if host == "0.0.0.0" else host)
         endpoint = f"http://{public_host}:{actual_port}"
+        # Register with tracker so other nodes can auto-join this model.
+        total_layers = getattr(node.backend, "total_layers", None)
+        try:
+            reg_resp = _post_json(
+                f"{tracker_url}/v1/nodes/register",
+                {
+                    "endpoint": endpoint,
+                    "model": model_id.split("/")[-1],
+                    "hf_repo": model_id,
+                    "num_layers": total_layers,
+                    "shard_start": shard_start,
+                    "shard_end": shard_end,
+                    "hardware_profile": hw,
+                    "wallet_address": address,
+                    "quantization": quantization,
+                    "score": 1.0,
+                    "tracker_mode": (shard_start == 0),
+                },
+            )
+            node_id = reg_resp.get("node_id", "?")
+            print(f"  Registered with tracker — node ID: {node_id}", flush=True)
+            _start_heartbeat(tracker_url, node_id)
+        except Exception as exc:
+            print(f"  Warning: tracker registration failed: {exc}", flush=True)
+
         print(
             f"\n{'=' * 32}\n"
             f"meshnet-node ready\n"
@@ -132,7 +193,79 @@ def run_startup(
     if shard_start is not None or shard_end is not None:
         raise ValueError("--shard-start / --shard-end require --model-id")
 
-    # 3. Shard assignment from tracker
+    # 3a. Auto-join: query tracker for network-wide HF model assignment.
+    print("Querying tracker for network assignment...", flush=True)
+    assign_qs = urllib.parse.urlencode({"device": device, "vram_mb": vram_mb})
+    net_assignment: dict = {}
+    try:
+        net_assignment = _get_json(f"{tracker_url}/v1/network/assign?{assign_qs}")
+    except Exception as exc:
+        print(f"  (auto-join unavailable: {exc})", flush=True)
+    assigned_hf_repo: str | None = net_assignment.get("hf_repo")
+    _gap_found: bool = bool(net_assignment.get("gap_found", False))
+
+    if assigned_hf_repo and _gap_found:
+        assigned_shard_start: int = net_assignment["shard_start"]
+        assigned_shard_end: int = net_assignment["shard_end"]
+        assigned_num_layers: int = net_assignment["num_layers"]
+        print(
+            f"  Assigned: {assigned_hf_repo} "
+            f"layers {assigned_shard_start}–{assigned_shard_end} "
+            f"(of {assigned_num_layers})",
+            flush=True,
+        )
+        print("Loading real PyTorch model shard...", flush=True)
+        node = TorchNodeServer(
+            host=host,
+            port=port,
+            model_id=assigned_hf_repo,
+            shard_start=assigned_shard_start,
+            shard_end=assigned_shard_end,
+            quantization=quantization,
+            tracker_url=tracker_url,
+        )
+        actual_port = node.start()
+        public_host = advertise_host or (socket.getfqdn() if host == "0.0.0.0" else host)
+        endpoint = f"http://{public_host}:{actual_port}"
+        try:
+            reg_resp = _post_json(
+                f"{tracker_url}/v1/nodes/register",
+                {
+                    "endpoint": endpoint,
+                    "model": assigned_hf_repo.split("/")[-1],
+                    "hf_repo": assigned_hf_repo,
+                    "num_layers": assigned_num_layers,
+                    "shard_start": assigned_shard_start,
+                    "shard_end": assigned_shard_end,
+                    "hardware_profile": hw,
+                    "wallet_address": address,
+                    "quantization": quantization,
+                    "score": 1.0,
+                    "tracker_mode": (assigned_shard_start == 0),
+                },
+            )
+            node_id = reg_resp.get("node_id", "?")
+            print(f"  Registered with tracker — node ID: {node_id}", flush=True)
+            _start_heartbeat(tracker_url, node_id)
+        except Exception as exc:
+            print(f"  Warning: tracker registration failed: {exc}", flush=True)
+        shard_count = assigned_shard_end - assigned_shard_start + 1
+        print(
+            f"\n{'=' * 32}\n"
+            f"meshnet-node ready (auto-joined)\n"
+            f"  Wallet:       {address}\n"
+            f"  Model ID:     {assigned_hf_repo}\n"
+            f"  Shard:        layers {assigned_shard_start}–{assigned_shard_end} "
+            f"({shard_count} of {assigned_num_layers})\n"
+            f"  Quantization: {quantization}\n"
+            f"  Endpoint:     {endpoint}\n"
+            f"  Hardware:     {device.upper()}\n"
+            f"{'=' * 32}",
+            flush=True,
+        )
+        return node
+
+    # 3b. Shard assignment from tracker (stub-model / preset-based path)
     print("Querying tracker for shard assignment...", flush=True)
     assign_qs = urllib.parse.urlencode({
         "model": model,

packages/tracker/meshnet_tracker/server.py

@@ -52,7 +52,7 @@ DEFAULT_BENCHMARK_TOKENS_PER_SEC = 1.0
 class _NodeEntry:
     __slots__ = (
         "node_id", "endpoint", "shard_start", "shard_end",
-        "model", "shard_checksum", "hardware_profile", "wallet_address",
+        "model", "hf_repo", "num_layers", "shard_checksum", "hardware_profile", "wallet_address",
         "score", "vram_bytes", "ram_bytes", "quantizations",
         "benchmark_tokens_per_sec", "quantization", "managed_assignment",
         "pending_directives", "last_heartbeat", "tracker_mode",
@@ -76,6 +76,8 @@ class _NodeEntry:
         quantization: str | None = None,
         managed_assignment: bool = False,
         tracker_mode: bool = False,
+        hf_repo: str | None = None,
+        num_layers: int | None = None,
     ) -> None:
         self.node_id = node_id
         self.endpoint = endpoint
@@ -93,6 +95,8 @@ class _NodeEntry:
         self.quantization = quantization
         self.managed_assignment = managed_assignment
         self.tracker_mode = tracker_mode
+        self.hf_repo = hf_repo
+        self.num_layers = num_layers
         self.pending_directives: list[dict] = []
         self.last_heartbeat: float = time.monotonic()
 
@@ -254,7 +258,12 @@ def _purge_expired_nodes_locked(server: "_TrackerHTTPServer") -> list[str]:
         if (now - entry.last_heartbeat) > server.heartbeat_timeout
     ]
     for node_id in expired_ids:
-        del server.registry[node_id]
+        entry = server.registry.pop(node_id)
+        print(
+            f"[tracker] node expired: {node_id[:8]}  {entry.endpoint}  "
+            f"(no heartbeat for >{server.heartbeat_timeout:.0f}s)",
+            flush=True,
+        )
     if expired_ids:
         _rebalance_all_locked(server)
     return expired_ids
@@ -426,6 +435,8 @@ class _TrackerHandler(http.server.BaseHTTPRequestHandler):
             self._handle_routes(parsed)
         elif parsed.path == "/v1/nodes/assign":
             self._handle_assign(parsed)
+        elif parsed.path == "/v1/network/assign":
+            self._handle_network_assign(parsed)
         elif parsed.path == "/v1/models":
             self._handle_models()
         elif parsed.path.startswith("/v1/coverage/"):
@@ -607,6 +618,18 @@ class _TrackerHandler(http.server.BaseHTTPRequestHandler):
             return
 
         tracker_mode = bool(body.get("tracker_mode", False))
+        hf_repo = body.get("hf_repo")
+        if hf_repo is not None and not isinstance(hf_repo, str):
+            self._send_json(400, {"error": "hf_repo must be a string"})
+            return
+        num_layers_body = body.get("num_layers")
+        num_layers: int | None = None
+        if num_layers_body is not None:
+            try:
+                num_layers = int(num_layers_body)
+            except (TypeError, ValueError):
+                self._send_json(400, {"error": "num_layers must be an integer"})
+                return
 
         node_id = str(uuid.uuid4())
         entry = _NodeEntry(
@@ -626,9 +649,23 @@ class _TrackerHandler(http.server.BaseHTTPRequestHandler):
             quantization=quantization,
             managed_assignment=not explicit_shard,
             tracker_mode=tracker_mode,
+            hf_repo=hf_repo,
+            num_layers=num_layers,
         )
         with server.lock:
             self._purge_expired_nodes()
+            # Dedup: if this endpoint is already registered, remove the old entry first.
+            stale_ids = [
+                eid for eid, e in server.registry.items()
+                if e.endpoint == entry.endpoint.rstrip("/")
+            ]
+            for eid in stale_ids:
+                old = server.registry.pop(eid)
+                print(
+                    f"[tracker] node re-registered: replaced {eid[:8]} with {node_id[:8]}"
+                    f"  {old.endpoint}",
+                    flush=True,
+                )
             server.registry[node_id] = entry
             if entry.managed_assignment:
                 _rebalance_model_locked(server, model)
@@ -636,6 +673,13 @@ class _TrackerHandler(http.server.BaseHTTPRequestHandler):
             if assignment_directive is not None:
                 entry.pending_directives.clear()
 
+        shard_info = f"layers {shard_start}-{shard_end}" if shard_start is not None else "unsharded"
+        repo_info = f" [{hf_repo}]" if hf_repo else ""
+        print(
+            f"[tracker] node registered: {node_id[:8]}  {endpoint}  {model}{repo_info}  {shard_info}",
+            flush=True,
+        )
+
         payload = {"node_id": node_id}
         if assignment_directive is not None:
             payload["directive"] = assignment_directive
@@ -653,6 +697,10 @@ class _TrackerHandler(http.server.BaseHTTPRequestHandler):
             _rebalance_model_locked(server, entry.model or "stub-model")
             directives = list(entry.pending_directives)
             entry.pending_directives.clear()
+        print(
+            f"[tracker] heartbeat: {node_id[:8]}  {entry.endpoint}",
+            flush=True,
+        )
         if directives:
             self._send_json(200, {"directives": directives})
         else:
@@ -751,6 +799,111 @@ class _TrackerHandler(http.server.BaseHTTPRequestHandler):
             **({"hf_repo": preset["hf_repo"]} if "hf_repo" in preset else {}),
         })
 
+    def _handle_network_assign(self, parsed: urllib.parse.ParseResult):
+        """Assign a new node to fill the biggest uncovered shard gap across HF-model nodes.
+
+        Query params:
+          vram_mb  — integer VRAM in MB (0 = CPU-only node)
+          device   — "cuda" | "cpu"
+          hf_repo  — optional; if set, restrict search to this repo only
+
+        Returns:
+          {hf_repo, shard_start, shard_end, num_layers, gap_found}
+          gap_found=true means a real uncovered gap was assigned; false means redundancy.
+        """
+        server: _TrackerHTTPServer = self.server  # type: ignore[assignment]
+        params = urllib.parse.parse_qs(parsed.query)
+        try:
+            vram_mb = int(params.get("vram_mb", ["0"])[0])
+        except ValueError:
+            vram_mb = 0
+        device = params.get("device", ["cpu"])[0]
+        filter_repo = params.get("hf_repo", [None])[0]  # optional repo filter
+
+        with server.lock:
+            self._purge_expired_nodes()
+            all_nodes = list(server.registry.values())
+
+        # Collect only nodes that registered a real HF model (have hf_repo + shard bounds).
+        hf_nodes = [
+            n for n in all_nodes
+            if n.hf_repo
+            and n.shard_start is not None
+            and n.shard_end is not None
+            and n.num_layers is not None
+            and (filter_repo is None or n.hf_repo == filter_repo)
+        ]
+
+        if not hf_nodes:
+            msg = (
+                f"no HF-model nodes registered for {filter_repo!r}"
+                if filter_repo
+                else "no HF-model nodes registered; cannot assign shards"
+            )
+            self._send_json(503, {"error": msg})
+            return
+
+        # Group by hf_repo; pick the one with the largest total_layers and biggest gap.
+        from collections import defaultdict
+        repo_groups: dict = defaultdict(list)
+        repo_layers: dict = {}
+        for n in hf_nodes:
+            repo_groups[n.hf_repo].append(n)
+            # Use the largest num_layers seen for this repo.
+            if n.hf_repo not in repo_layers or n.num_layers > repo_layers[n.hf_repo]:
+                repo_layers[n.hf_repo] = n.num_layers
+
+        # Pick the repo where the gap is largest (most work to do).
+        best_repo = None
+        best_gap_size = -1
+        best_gap_start = 0
+        best_num_layers = 0
+
+        for repo, nodes in repo_groups.items():
+            total = repo_layers[repo]
+            covered = sorted(
+                [(n.shard_start, n.shard_end) for n in nodes],
+                key=lambda t: t[0],
+            )
+            # Walk from 0 to find first uncovered layer.
+            gap_start = 0
+            for s, e in covered:
+                if s <= gap_start:
+                    gap_start = max(gap_start, e + 1)
+                else:
+                    break
+            gap_size = max(0, (total - 1) - gap_start + 1)  # layers remaining uncovered
+            if gap_size > best_gap_size:
+                best_gap_size = gap_size
+                best_gap_start = gap_start
+                best_repo = repo
+                best_num_layers = total
+
+        gap_found = best_gap_size > 0
+        if not gap_found:
+            # All shards are covered — still assign to the model with most nodes for redundancy.
+            best_repo = max(repo_groups, key=lambda r: len(repo_groups[r]))
+            best_gap_start = 0
+            best_num_layers = repo_layers[best_repo]
+
+        # Capacity: CPU nodes get at most half the layers; CUDA nodes based on VRAM.
+        total_l = best_num_layers
+        if device == "cuda" and vram_mb >= 8192:
+            max_layers = total_l
+        else:
+            max_layers = max(1, total_l // 2)
+
+        shard_start = best_gap_start
+        shard_end = min(total_l - 1, shard_start + max_layers - 1)
+
+        self._send_json(200, {
+            "hf_repo": best_repo,
+            "shard_start": shard_start,
+            "shard_end": shard_end,
+            "num_layers": total_l,
+            "gap_found": gap_found,
+        })
+
     def _handle_route(self, parsed: urllib.parse.ParseResult):
         server: _TrackerHTTPServer = self.server  # type: ignore[assignment]
         params = urllib.parse.parse_qs(parsed.query)
@@ -761,15 +914,28 @@ class _TrackerHandler(http.server.BaseHTTPRequestHandler):
 
         model = model_list[0]
         preset = server.model_presets.get(model)
-        if preset is None:
-            self._send_json(404, {"error": f"unknown model preset: {model!r}"})
-            return
-
-        required_start, required_end = _preset_layer_bounds(preset)
 
         with server.lock:
             self._purge_expired_nodes()
+            if preset is not None:
+                # Preset-based routing (stub-model system).
                 alive = [node for node in server.registry.values() if node.model == model]
+                required_start, required_end = _preset_layer_bounds(preset)
+            else:
+                # HF model routing: match by hf_repo (full) or model short name.
+                alive = [
+                    node for node in server.registry.values()
+                    if (node.hf_repo == model or node.model == model)
+                    and node.shard_start is not None
+                    and node.shard_end is not None
+                    and node.num_layers is not None
+                ]
+                if not alive:
+                    self._send_json(404, {"error": f"no nodes registered for model {model!r}"})
+                    return
+                required_start = 0
+                required_end = max(n.num_layers for n in alive) - 1  # type: ignore[type-var]
+
         if server.contracts is not None:
             alive = [
                 node for node in alive
@@ -871,7 +1037,7 @@ class TrackerServer:
         self,
         host: str = "127.0.0.1",
         port: int = 0,
-        heartbeat_timeout: float = 30.0,
+        heartbeat_timeout: float = 90.0,
         rebalance_interval: float = 30.0,
         model_presets: dict | None = None,
         contracts: Any | None = None,

tests/test_node_startup.py

@@ -507,6 +507,163 @@ def test_second_node_downloads_same_shard_from_peer_without_huggingface(
         tracker.stop()
 
 
+def test_network_assign_gap_found_field():
+    """network/assign sets gap_found=True when a real gap exists, False when fully covered."""
+    import json as _json
+    import urllib.request as _ur
+
+    tracker = TrackerServer()
+    port = tracker.start()
+    try:
+        # Register a node covering only layers 0-11 of a 24-layer model.
+        data = _json.dumps({
+            "endpoint": "http://127.0.0.1:9200",
+            "model": "Qwen2.5-0.5B-Instruct",
+            "hf_repo": "Qwen/Qwen2.5-0.5B-Instruct",
+            "num_layers": 24,
+            "shard_start": 0,
+            "shard_end": 11,
+            "hardware_profile": {},
+            "score": 1.0,
+        }).encode()
+        req = _ur.Request(
+            f"http://127.0.0.1:{port}/v1/nodes/register",
+            data=data,
+            headers={"Content-Type": "application/json"},
+            method="POST",
+        )
+        with _ur.urlopen(req) as r:
+            r.read()
+
+        # A new node should be told there is a gap (layers 12-23).
+        resp = _get_json(
+            f"http://127.0.0.1:{port}/v1/network/assign?device=cpu&vram_mb=0"
+            "&hf_repo=Qwen/Qwen2.5-0.5B-Instruct"
+        )
+        assert resp["gap_found"] is True
+        assert resp["shard_start"] == 12, f"expected gap at 12, got {resp['shard_start']}"
+        assert resp["shard_end"] == 23
+
+        # Register the second node covering the gap.
+        data2 = _json.dumps({
+            "endpoint": "http://127.0.0.1:9201",
+            "model": "Qwen2.5-0.5B-Instruct",
+            "hf_repo": "Qwen/Qwen2.5-0.5B-Instruct",
+            "num_layers": 24,
+            "shard_start": 12,
+            "shard_end": 23,
+            "hardware_profile": {},
+            "score": 1.0,
+        }).encode()
+        req2 = _ur.Request(
+            f"http://127.0.0.1:{port}/v1/nodes/register",
+            data=data2,
+            headers={"Content-Type": "application/json"},
+            method="POST",
+        )
+        with _ur.urlopen(req2) as r:
+            r.read()
+
+        # Now fully covered — gap_found should be False.
+        resp2 = _get_json(
+            f"http://127.0.0.1:{port}/v1/network/assign?device=cpu&vram_mb=0"
+            "&hf_repo=Qwen/Qwen2.5-0.5B-Instruct"
+        )
+        assert resp2["gap_found"] is False
+    finally:
+        tracker.stop()
+
+
+def test_route_finds_hf_model_across_two_nodes():
+    """Tracker /v1/route returns ordered route for HF model even without a preset."""
+    import json as _json
+    import urllib.request as _ur
+
+    tracker = TrackerServer()
+    port = tracker.start()
+    try:
+        def register(endpoint, shard_start, shard_end):
+            data = _json.dumps({
+                "endpoint": endpoint,
+                "model": "Qwen2.5-0.5B-Instruct",
+                "hf_repo": "Qwen/Qwen2.5-0.5B-Instruct",
+                "num_layers": 24,
+                "shard_start": shard_start,
+                "shard_end": shard_end,
+                "hardware_profile": {},
+                "score": 1.0,
+            }).encode()
+            req = _ur.Request(
+                f"http://127.0.0.1:{port}/v1/nodes/register",
+                data=data,
+                headers={"Content-Type": "application/json"},
+                method="POST",
+            )
+            with _ur.urlopen(req) as r:
+                r.read()
+
+        register("http://127.0.0.1:9300", 0, 11)
+        register("http://127.0.0.1:9301", 12, 23)
+
+        # Route by hf_repo (full identifier).
+        resp = _get_json(
+            f"http://127.0.0.1:{port}/v1/route?model=Qwen/Qwen2.5-0.5B-Instruct"
+        )
+        assert resp["route"] == ["http://127.0.0.1:9300", "http://127.0.0.1:9301"]
+
+        # Route also works by short model name.
+        resp2 = _get_json(
+            f"http://127.0.0.1:{port}/v1/route?model=Qwen2.5-0.5B-Instruct"
+        )
+        assert resp2["route"] == ["http://127.0.0.1:9300", "http://127.0.0.1:9301"]
+    finally:
+        tracker.stop()
+
+
+def test_register_deduplicates_same_endpoint():
+    """Re-registering the same endpoint replaces the old entry, not duplicates it."""
+    import json as _json
+    import urllib.request as _ur
+
+    tracker = TrackerServer()
+    port = tracker.start()
+    try:
+        def register(shard_start, shard_end):
+            data = _json.dumps({
+                "endpoint": "http://127.0.0.1:9400",
+                "model": "Qwen2.5-0.5B-Instruct",
+                "hf_repo": "Qwen/Qwen2.5-0.5B-Instruct",
+                "num_layers": 24,
+                "shard_start": shard_start,
+                "shard_end": shard_end,
+                "hardware_profile": {},
+                "score": 1.0,
+            }).encode()
+            req = _ur.Request(
+                f"http://127.0.0.1:{port}/v1/nodes/register",
+                data=data,
+                headers={"Content-Type": "application/json"},
+                method="POST",
+            )
+            with _ur.urlopen(req) as r:
+                return _json.loads(r.read())
+
+        register(0, 23)  # initial full-model registration
+        register(12, 23)  # re-register with corrected shard range
+
+        # After re-register, tracker should see only one node at 12-23 for this endpoint.
+        # If both were still registered, the gap scan would find no gap (0-23 still covers).
+        # With dedup, the old 0-23 is gone and a real gap 0-11 exists.
+        assign_resp = _get_json(
+            f"http://127.0.0.1:{port}/v1/network/assign?device=cpu&vram_mb=0"
+            "&hf_repo=Qwen/Qwen2.5-0.5B-Instruct"
+        )
+        assert assign_resp["gap_found"] is True
+        assert assign_resp["shard_start"] == 0, "old 0-23 entry should have been replaced"
+    finally:
+        tracker.stop()
+
+
 def test_startup_cpu_fallback(tmp_path, monkeypatch):
     """Node starts with CPU warning when no GPU is detected."""
     import meshnet_node.startup as startup_mod