Agent Conversation: anthropic/claude-opus-4.6

Model: anthropic/claude-opus-4.6
Total steps: 8
Messages: 18
UserStep 0

Task: ml-federated-aggregation

Federated Learning Aggregation Strategy Design

Research Question

Design a novel server-side aggregation strategy for federated learning that achieves better convergence and higher test accuracy under heterogeneous (non-IID) data distributions across clients.

Background

Federated Learning (FL) trains a shared global model across many clients without centralizing data. The canonical algorithm, FedAvg, simply averages client model parameters weighted by sample count. However, when client data distributions are heterogeneous (non-IID), FedAvg suffers from "client drift" where local updates diverge, leading to slow convergence or poor final accuracy. Research has produced several improvements: FedProx adds a proximal penalty to local objectives, SCAFFOLD uses control variates for variance reduction, and methods like FedNova normalize updates by local steps. The aggregation strategy — how the server combines client updates into the global model — is the core algorithmic component that determines convergence behavior.

Task

Modify the ServerAggregator class in custom_fl_aggregation.py. You must implement the aggregate() method that takes the current global model state, a list of client updates (model parameters + metadata), and returns the new global model state. You may also customize client selection via select_clients().

Interface

class ServerAggregator:
    def __init__(self, global_model, args):
        # Initialize aggregation state (momentum buffers, control variates, etc.)

    def aggregate(self, global_state_dict, client_updates, round_num):
        # global_state_dict: OrderedDict of current global model parameters
        # client_updates: list of (state_dict, num_samples, avg_loss) tuples
        # round_num: current communication round (0-indexed)
        # Returns: OrderedDict of updated global model parameters

    def select_clients(self, num_available, num_to_select, round_num):
        # Returns: list of client indices to participate this round

Evaluation

The aggregation strategy is evaluated on three benchmarks with non-IID data:

  1. CIFAR-10 with Dirichlet split (alpha=0.1) — 100 clients, image classification
  2. FEMNIST (EMNIST ByClass) with Dirichlet split — 100 clients, character recognition
  3. Shakespeare (next character prediction) — naturally non-IID by speaker

Metric: test accuracy after 200 communication rounds (higher is better). Each round, 10 of 100 clients are selected, each trains for 5 local epochs with SGD (lr=0.01).

flower/custom_fl_aggregation.py [EDITABLE — lines 353–424 only]

     1: # Custom federated learning aggregation strategy for MLS-Bench
     2: #
     3: # EDITABLE section: ServerAggregator class (aggregate method + helpers).
     4: # FIXED sections: everything else (config, data partitioning, client training,
     5: #                 FL simulation loop, evaluation).
     6: import argparse
     
AssistantStep 1edit
Tool Input
1{
2  "op": "replace",
3  "filename": "flower/custom_fl_aggregation.py",
4  "start_line": 353,
5  "end_line": 425,
6  "content": "class ServerAggregator:\n    \"\"\"CGMA — Consensus-Guided Momentum Aggregation.\n\n    A novel federated aggregation strategy that addresses non-IID client drift\n    through three synergistic mechanisms:\n\n    1. **Adaptive Update Clipping**: Clips client pseudo-gradients whose norm\n       exceeds a data-driven threshold (multiple of the median norm), providing\n       robustness against outlier updates from highly skewed local distributions.\n\n    2. **Consensus-Guided Reweighting**: Maintains an EMA of past aggregated\n       update directions as a \"consensus trajectory\". Each round, client updates\n       are reweighted by their cosine similarity with this trajectory — clients\n       aligned with the historical optimization direction get higher weight,\n       while contradictory updates are dampened. Using historical EMA (not\n       current-round average) provides an independent, stable reference.\n\n    3. **Polyak Heavy-Ball Momentum**: Adds a fraction of the previous server\n       step to the current update, smoothing the trajectory and reducing\n       variance from stochastic client sampling (10% participation per round).\n\n    The combination is novel: clipping handles magnitude outliers, consensus\n    reweighting handles directional outliers, and momentum provides temporal\n    smoothing — each addressing a different variance source in non-IID FL.\n    \"\"\"\n\n    def __init__(self, global_model, args):\n        self.args = args\n        # Heavy-ball momentum\n        self.prev_global_state = None\n        self.beta_momentum = 0.5\n        # EMA of update directions for consensus reference\n        self.ema_direction = None\n        self.beta_ema = 0.7\n        # Consensus reweighting strength\n        self.consensus_strength = 0.5\n        # Adaptive clipping factor (multiple of median norm)\n        self.clip_factor = 2.0\n\n    def aggregate(self, global_state_dict, client_updates, round_num):\n        n_clients = len(client_updates)\n        total_samples = sum(n for _, n, _ in client_updates)\n        keys = list(global_state_dict.keys())\n\n        # --- 1. Compute per-client deltas (pseudo-gradients) ---\n        client_deltas = []\n        for state_dict, n_samples, avg_loss in client_updates:\n            delta = OrderedDict()\n            for key in keys:\n                delta[key] = state_dict[key].float() - global_state_dict[key].float()\n            client_deltas.append(delta)\n\n        # --- 2. Adaptive clipping based on median norm ---\n        norms = []\n        for d in client_deltas:\n            norm_sq = sum(d[k].pow(2).sum().item() for k in keys)\n            norms.append(norm_sq ** 0.5)\n\n        sorted_norms = sorted(norms)\n        median_norm = sorted_norms[n_clients // 2]\n        threshold = self.clip_factor * max(median_norm, 1e-8)\n\n        for i in range(n_clients):\n            if norms[i] > threshold:\n                scale = threshold / norms[i]\n                for k in keys:\n                    client_deltas[i][k] *= scale\n\n        # --- 3. Consensus-guided reweighting ---\n        sample_weights = [client_updates[i][1] / total_samples\n                          for i in range(n_clients)]\n\n        if self.ema_direction is not None:\n            # Cosine similarity of each client delta with EMA direction\n            ema_norm_sq = sum(\n                self.ema_direction[k].pow(2).sum().item() for k in keys)\n            ema_norm = max(ema_norm_sq ** 0.5, 1e-8)\n\n            sims = []\n            for i in range(n_clients):\n                dot = sum((client_deltas[i][k] * self.ema_direction[k]).sum().item()\n                          for k in keys)\n                c_norm = sum(client_deltas[i][k].pow(2).sum().item()\n                             for k in keys) ** 0.5\n                c_norm = max(c_norm, 1e-8)\n                sims.append(dot / (c_norm * ema_norm))\n\n            # Boost aligned clients, leave others at baseline\n            weights = []\n            for i in range(n_clients):\n                w = sample_weights[i] * (\n                    1.0 + self.consensus_strength * max(sims[i], 0.0))\n                weights.append(w)\n            w_sum = sum(weights)\n            weights = [w / w_sum for w in weights]\n        else:\n            weights = sample_weights\n\n        # --- 4. Weighted aggregation of deltas ---\n        avg_delta = OrderedDict()\n        for key in keys:\n            avg_delta[key] = sum(\n                client_deltas[i][key] * weights[i] for i in range(n_clients))\n\n        # --- 5. Update EMA direction for future consensus ---\n        if self.ema_direction is None:\n            self.ema_direction = OrderedDict()\n            for k in keys:\n                self.ema_direction[k] = avg_delta[k].clone()\n        else:\n            for k in keys:\n                self.ema_direction[k] = (self.beta_ema * self.ema_direction[k]\n                                         + (1 - self.beta_ema) * avg_delta[k])\n\n        # --- 6. Polyak heavy-ball momentum ---\n        if self.prev_global_state is not None:\n            momentum = OrderedDict()\n            for k in keys:\n                momentum[k] = self.beta_momentum * (\n                    global_state_dict[k].float()\n                    - self.prev_global_state[k].float())\n        else:\n            momentum = {k: torch.zeros_like(global_state_dict[k].float())\n                        for k in keys}\n\n        # Store current state before update\n        self.prev_global_state = OrderedDict()\n        for k in keys:\n            self.prev_global_state[k] = global_state_dict[k].clone()\n\n        # --- 7. Apply: θ_{t+1} = θ_t + Δ_t + β*(θ_t − θ_{t-1}) ---\n        new_state = OrderedDict()\n        for key in keys:\n            updated = (global_state_dict[key].float()\n                       + avg_delta[key] + momentum[key])\n            new_state[key] = updated.to(global_state_dict[key].dtype)\n\n        return new_state\n\n    def select_clients(self, num_available, num_to_select, round_num):\n        return random.sample(range(num_available),\n                             min(num_to_select, num_available))\n"
7}
Tool ResultStep 1
ERROR: Lines 353..425 exceed the editable range. You may only edit lines 353–424.

[Current file: flower/custom_fl_aggregation.py | editable: 353–424 | total: 521 lines]
   353  class ServerAggregator:
   354      """Server-side aggregation strategy for federated learning.
   355  
       ... (66 more lines) ...
   422              list of client indices to participate
   423          """
   424          return random.sample(range(num_available), min(num_to_select, num_available))
AssistantStep 2edit
Tool Input
1{
2  "op": "replace",
3  "filename": "flower/custom_fl_aggregation.py",
4  "start_line": 353,
5  "end_line": 424,
6  "content": "class ServerAggregator:\n    \"\"\"CGMA — Consensus-Guided Momentum Aggregation.\n    Novel aggregation: adaptive clipping + consensus reweighting via EMA\n    trajectory + Polyak heavy-ball momentum for non-IID FL.\n    \"\"\"\n\n    def __init__(self, global_model, args):\n        self.args = args\n        self.prev_global_state = None\n        self.beta_momentum = 0.5\n        self.ema_direction = None\n        self.beta_ema = 0.7\n        self.consensus_strength = 0.5\n        self.clip_factor = 2.0\n\n    def aggregate(self, global_state_dict, client_updates, round_num):\n        n_clients = len(client_updates)\n        total_samples = sum(n for _, n, _ in client_updates)\n        keys = list(global_state_dict.keys())\n\n        # 1. Per-client deltas\n        client_deltas = []\n        for state_dict, n_samples, avg_loss in client_updates:\n            delta = OrderedDict()\n            for key in keys:\n                delta[key] = state_dict[key].float() - global_state_dict[key].float()\n            client_deltas.append(delta)\n\n        # 2. Adaptive clipping (median-based threshold)\n        norms = []\n        for d in client_deltas:\n            norms.append(sum(d[k].pow(2).sum().item() for k in keys) ** 0.5)\n        median_norm = sorted(norms)[n_clients // 2]\n        threshold = self.clip_factor * max(median_norm, 1e-8)\n        for i in range(n_clients):\n            if norms[i] > threshold:\n                s = threshold / norms[i]\n                for k in keys:\n                    client_deltas[i][k] *= s\n\n        # 3. Consensus-guided reweighting\n        sw = [client_updates[i][1] / total_samples for i in range(n_clients)]\n        if self.ema_direction is not None:\n            en = max(sum(self.ema_direction[k].pow(2).sum().item() for k in keys) ** 0.5, 1e-8)\n            sims = []\n            for i in range(n_clients):\n                dot = sum((client_deltas[i][k] * self.ema_direction[k]).sum().item() for k in keys)\n                cn = max(sum(client_deltas[i][k].pow(2).sum().item() for k in keys) ** 0.5, 1e-8)\n                sims.append(dot / (cn * en))\n            weights = [sw[i] * (1.0 + self.consensus_strength * max(sims[i], 0.0)) for i in range(n_clients)]\n            ws = sum(weights)\n            weights = [w / ws for w in weights]\n        else:\n            weights = sw\n\n        # 4. Weighted aggregation\n        avg_delta = OrderedDict()\n        for key in keys:\n            avg_delta[key] = sum(client_deltas[i][key] * weights[i] for i in range(n_clients))\n\n        # 5. Update EMA direction\n        if self.ema_direction is None:\n            self.ema_direction = OrderedDict()\n            for k in keys:\n                self.ema_direction[k] = avg_delta[k].clone()\n        else:\n            for k in keys:\n                self.ema_direction[k] = self.beta_ema * self.ema_direction[k] + (1 - self.beta_ema) * avg_delta[k]\n\n        # 6. Polyak heavy-ball momentum\n        if self.prev_global_state is not None:\n            mom = {k: self.beta_momentum * (global_state_dict[k].float() - self.prev_global_state[k].float()) for k in keys}\n        else:\n            mom = {k: torch.zeros_like(global_state_dict[k].float()) for k in keys}\n        self.prev_global_state = OrderedDict((k, global_state_dict[k].clone()) for k in keys)\n\n        # 7. Apply: θ_{t+1} = θ_t + Δ_t + β*(θ_t − θ_{t-1})\n        new_state = OrderedDict()\n        for key in keys:\n            new_state[key] = (global_state_dict[key].float() + avg_delta[key] + mom[key]).to(global_state_dict[key].dtype)\n        return new_state\n\n    def select_clients(self, num_available, num_to_select, round_num):\n        return random.sample(range(num_available), min(num_to_select, num_available))"
7}
Tool ResultStep 2
OK: Replaced lines 353..424 with 84 line(s) in flower/custom_fl_aggregation.py. Editable range: 353–436.

[Current file: flower/custom_fl_aggregation.py | editable: 353–436 | total: 533 lines]
   353  class ServerAggregator:
   354      """CGMA — Consensus-Guided Momentum Aggregation.
   355      Novel aggregation: adaptive clipping + consensus reweighting via EMA
       ... (78 more lines) ...
   434  
   435      def select_clients(self, num_available, num_to_select, round_num):
   436          return random.sample(range(num_available), min(num_to_select, num_available))
AssistantStep 3test
Tool ResultStep 3
[Test #1] (2 tests remaining; call submit(n=N) to choose which test result to submit as final)

### cifar10 (scripts/cifar10.sh)
Training metrics (last rounds):
TRAIN_METRICS round=180 avg_loss=0.0961 round_time=3.4s
TRAIN_METRICS round=185 avg_loss=0.1110 round_time=4.1s
TRAIN_METRICS round=190 avg_loss=0.0339 round_time=3.2s
TRAIN_METRICS round=195 avg_loss=0.0282 round_time=3.8s
TRAIN_METRICS round=200 avg_loss=0.0489 round_time=3.4s
Evaluation progress:
EVAL round=160 test_loss=1.6712 test_accuracy=0.6418 elapsed=593s
EVAL round=170 test_loss=1.8197 test_accuracy=0.6157 elapsed=636s
EVAL round=180 test_loss=1.6126 test_accuracy=0.6477 elapsed=668s
EVAL round=190 test_loss=1.5527 test_accuracy=0.6687 elapsed=708s
EVAL round=200 test_loss=1.7011 test_accuracy=0.6543 elapsed=746s
Final metrics (cifar10):
test_accuracy_cifar10: 0.6543
test_loss_cifar10: 1.7011
best_accuracy_cifar10: 0.6687

### femnist (scripts/femnist.sh)
Training metrics (last rounds):
TRAIN_METRICS round=180 avg_los
AssistantStep 4edit
Tool Input
1{
2  "op": "replace",
3  "filename": "flower/custom_fl_aggregation.py",
4  "start_line": 353,
5  "end_line": 436,
6  "content": "class ServerAggregator:\n    \"\"\"CGMA — Consensus-Guided Momentum Aggregation with Adaptive Decay.\n    Novel aggregation combining:\n    1. Adaptive median-based clipping for outlier robustness\n    2. Consensus reweighting via EMA trajectory alignment\n    3. Heavy-ball momentum with warm-up and decay\n    \"\"\"\n\n    def __init__(self, global_model, args):\n        self.args = args\n        self.prev_global_state = None\n        self.ema_direction = None\n        self.beta_ema = 0.8\n        self.consensus_strength = 0.5\n        self.clip_factor = 2.5\n        # Momentum schedule: warm up then hold\n        self.beta_momentum_max = 0.4\n        self.momentum_warmup_rounds = 10\n        # Server learning rate > 1 can sometimes help\n        self.server_lr = 1.0\n\n    def aggregate(self, global_state_dict, client_updates, round_num):\n        n_clients = len(client_updates)\n        total_samples = sum(n for _, n, _ in client_updates)\n        keys = list(global_state_dict.keys())\n\n        # Momentum schedule: linear warm-up\n        if round_num < self.momentum_warmup_rounds:\n            beta_m = self.beta_momentum_max * (round_num / self.momentum_warmup_rounds)\n        else:\n            beta_m = self.beta_momentum_max\n\n        # 1. Per-client deltas\n        client_deltas = []\n        for state_dict, n_samples, avg_loss in client_updates:\n            delta = OrderedDict()\n            for key in keys:\n                delta[key] = state_dict[key].float() - global_state_dict[key].float()\n            client_deltas.append(delta)\n\n        # 2. Adaptive clipping (median-based threshold)\n        norms = []\n        for d in client_deltas:\n            norms.append(sum(d[k].pow(2).sum().item() for k in keys) ** 0.5)\n        median_norm = sorted(norms)[n_clients // 2]\n        threshold = self.clip_factor * max(median_norm, 1e-8)\n        for i in range(n_clients):\n            if norms[i] > threshold:\n                s = threshold / norms[i]\n                for k in keys:\n                    client_deltas[i][k] *= s\n\n        # 3. Consensus-guided reweighting using EMA trajectory\n        sw = [client_updates[i][1] / total_samples for i in range(n_clients)]\n        if self.ema_direction is not None and round_num >= 3:\n            en = max(sum(self.ema_direction[k].pow(2).sum().item() for k in keys) ** 0.5, 1e-8)\n            sims = []\n            for i in range(n_clients):\n                dot = sum((client_deltas[i][k] * self.ema_direction[k]).sum().item() for k in keys)\n                cn = max(sum(client_deltas[i][k].pow(2).sum().item() for k in keys) ** 0.5, 1e-8)\n                sims.append(dot / (cn * en))\n            # Soft reweighting: boost aligned, slightly dampen misaligned\n            weights = []\n            for i in range(n_clients):\n                # Use sigmoid-like mapping: max(sim, -0.5) to avoid completely zeroing out\n                sim_clamped = max(sims[i], -0.3)\n                w = sw[i] * (1.0 + self.consensus_strength * sim_clamped)\n                weights.append(max(w, 1e-8))\n            ws = sum(weights)\n            weights = [w / ws for w in weights]\n        else:\n            weights = sw\n\n        # 4. Weighted aggregation\n        avg_delta = OrderedDict()\n        for key in keys:\n            avg_delta[key] = sum(client_deltas[i][key] * weights[i] for i in range(n_clients))\n\n        # 5. Update EMA direction\n        if self.ema_direction is None:\n            self.ema_direction = OrderedDict()\n            for k in keys:\n                self.ema_direction[k] = avg_delta[k].clone()\n        else:\n            for k in keys:\n                self.ema_direction[k] = self.beta_ema * self.ema_direction[k] + (1 - self.beta_ema) * avg_delta[k]\n\n        # 6. Polyak heavy-ball momentum\n        if self.prev_global_state is not None:\n            mom = {k: beta_m * (global_state_dict[k].float() - self.prev_global_state[k].float()) for k in keys}\n        else:\n            mom = {k: torch.zeros_like(global_state_dict[k].float()) for k in keys}\n        self.prev_global_state = OrderedDict((k, global_state_dict[k].clone()) for k in keys)\n\n        # 7. Apply: θ_{t+1} = θ_t + lr * Δ_t + β*(θ_t − θ_{t-1})\n        new_state = OrderedDict()\n        for key in keys:\n            new_state[key] = (global_state_dict[key].float() + self.server_lr * avg_delta[key] + mom[key]).to(global_state_dict[key].dtype)\n        return new_state\n\n    def select_clients(self, num_available, num_to_select, round_num):\n        return random.sample(range(num_available), min(num_to_select, num_available))"
7}
Tool ResultStep 4
OK: Replaced lines 353..436 with 102 line(s) in flower/custom_fl_aggregation.py. Editable range: 353–454.

[Current file: flower/custom_fl_aggregation.py | editable: 353–454 | total: 551 lines]
   353  class ServerAggregator:
   354      """CGMA — Consensus-Guided Momentum Aggregation with Adaptive Decay.
   355      Novel aggregation combining:
       ... (96 more lines) ...
   452  
   453      def select_clients(self, num_available, num_to_select, round_num):
   454          return random.sample(range(num_available), min(num_to_select, num_available))
AssistantStep 5test
Tool ResultStep 5
[Test #2] (1 test remaining; call submit(n=N) to choose which test result to submit as final)

### cifar10 (scripts/cifar10.sh)
Training metrics (last rounds):
TRAIN_METRICS round=180 avg_loss=0.0919 round_time=4.9s
TRAIN_METRICS round=185 avg_loss=0.0981 round_time=5.2s
TRAIN_METRICS round=190 avg_loss=0.0359 round_time=4.4s
TRAIN_METRICS round=195 avg_loss=0.0388 round_time=5.2s
TRAIN_METRICS round=200 avg_loss=0.0662 round_time=4.5s
Evaluation progress:
EVAL round=160 test_loss=1.5424 test_accuracy=0.6323 elapsed=710s
EVAL round=170 test_loss=1.6133 test_accuracy=0.6285 elapsed=765s
EVAL round=180 test_loss=1.5337 test_accuracy=0.6385 elapsed=810s
EVAL round=190 test_loss=1.3986 test_accuracy=0.6731 elapsed=859s
EVAL round=200 test_loss=1.6660 test_accuracy=0.6411 elapsed=910s
Final metrics (cifar10):
test_accuracy_cifar10: 0.6411
test_loss_cifar10: 1.6660
best_accuracy_cifar10: 0.6731

### femnist (scripts/femnist.sh)
Training metrics (last rounds):
TRAIN_METRICS round=180 avg_loss
AssistantStep 6edit
Tool Input
1{
2  "op": "replace",
3  "filename": "flower/custom_fl_aggregation.py",
4  "start_line": 353,
5  "end_line": 454,
6  "content": "class ServerAggregator:\n    \"\"\"CGMA — Consensus-Guided Momentum Aggregation.\n    Combines: (1) adaptive norm clipping, (2) lightweight consensus reweighting\n    via flattened vectors, (3) heavy-ball momentum with warm-up.\n    \"\"\"\n\n    def __init__(self, global_model, args):\n        self.args = args\n        self.prev_global_state = None\n        self.ema_flat = None  # flattened EMA direction\n        self.beta_ema = 0.8\n        self.consensus_strength = 0.5\n        self.clip_factor = 2.5\n        self.beta_momentum_max = 0.4\n        self.momentum_warmup = 10\n        self.keys = None\n\n    def _flatten(self, delta):\n        return torch.cat([delta[k].reshape(-1) for k in self.keys])\n\n    def aggregate(self, global_state_dict, client_updates, round_num):\n        n = len(client_updates)\n        total_samples = sum(ns for _, ns, _ in client_updates)\n        if self.keys is None:\n            self.keys = list(global_state_dict.keys())\n        keys = self.keys\n\n        # Momentum warm-up\n        beta_m = min(self.beta_momentum_max, self.beta_momentum_max * round_num / max(self.momentum_warmup, 1))\n\n        # 1. Per-client flat deltas\n        flat_deltas = []\n        for sd, ns, al in client_updates:\n            parts = []\n            for k in keys:\n                parts.append((sd[k].float() - global_state_dict[k].float()).reshape(-1))\n            flat_deltas.append(torch.cat(parts))\n\n        # 2. Adaptive clipping\n        norms = [fd.norm().item() for fd in flat_deltas]\n        median_norm = sorted(norms)[n // 2]\n        threshold = self.clip_factor * max(median_norm, 1e-8)\n        for i in range(n):\n            if norms[i] > threshold:\n                flat_deltas[i] *= (threshold / norms[i])\n\n        # 3. Consensus reweighting\n        sw = [client_updates[i][1] / total_samples for i in range(n)]\n        if self.ema_flat is not None and round_num >= 3:\n            ema_n = max(self.ema_flat.norm().item(), 1e-8)\n            sims = []\n            for i in range(n):\n                cn = max(flat_deltas[i].norm().item(), 1e-8)\n                dot = torch.dot(flat_deltas[i], self.ema_flat).item()\n                sims.append(dot / (cn * ema_n))\n            weights = []\n            for i in range(n):\n                sim_c = max(sims[i], -0.3)\n                w = sw[i] * (1.0 + self.consensus_strength * sim_c)\n                weights.append(max(w, 1e-8))\n            ws = sum(weights)\n            weights = [w / ws for w in weights]\n        else:\n            weights = sw\n\n        # 4. Weighted average delta (flat)\n        avg_flat = torch.zeros_like(flat_deltas[0])\n        for i in range(n):\n            avg_flat += flat_deltas[i] * weights[i]\n\n        # 5. Update EMA\n        if self.ema_flat is None:\n            self.ema_flat = avg_flat.clone()\n        else:\n            self.ema_flat = self.beta_ema * self.ema_flat + (1 - self.beta_ema) * avg_flat\n\n        # 6. Unflatten avg_delta\n        avg_delta = OrderedDict()\n        offset = 0\n        for k in keys:\n            shape = global_state_dict[k].shape\n            numel = global_state_dict[k].numel()\n            avg_delta[k] = avg_flat[offset:offset+numel].reshape(shape)\n            offset += numel\n\n        # 7. Momentum\n        if self.prev_global_state is not None:\n            mom = OrderedDict()\n            for k in keys:\n                mom[k] = beta_m * (global_state_dict[k].float() - self.prev_global_state[k].float())\n        else:\n            mom = {k: torch.zeros_like(global_state_dict[k].float()) for k in keys}\n        self.prev_global_state = OrderedDict((k, global_state_dict[k].clone()) for k in keys)\n\n        # 8. Apply update\n        new_state = OrderedDict()\n        for k in keys:\n            new_state[k] = (global_state_dict[k].float() + avg_delta[k] + mom[k]).to(global_state_dict[k].dtype)\n        return new_state\n\n    def select_clients(self, num_available, num_to_select, round_num):\n        return random.sample(range(num_available), min(num_to_select, num_available))"
7}
Tool ResultStep 6
OK: Replaced lines 353..454 with 102 line(s) in flower/custom_fl_aggregation.py. Editable range: 353–454.

[Current file: flower/custom_fl_aggregation.py | editable: 353–454 | total: 551 lines]
   353  class ServerAggregator:
   354      """CGMA — Consensus-Guided Momentum Aggregation.
   355      Combines: (1) adaptive norm clipping, (2) lightweight consensus reweighting
       ... (96 more lines) ...
   452  
   453      def select_clients(self, num_available, num_to_select, round_num):
   454          return random.sample(range(num_available), min(num_to_select, num_available))
AssistantStep 7test
Tool ResultStep 7
[Test #3] (0 tests remaining; call submit(n=N) to choose which test result to submit as final)

[NOTE] This was your last test. You MUST now call submit(n=X) to choose which test result to submit as your final answer.

### cifar10 (scripts/cifar10.sh)
[COMMAND FAILED exit=1]
Device: cuda
Loading dataset: cifar10
Number of clients: 100
Traceback (most recent call last):
  File "/srv/home/bohanlyu/MLS-Bench/vendor/workspace/ml-federated-aggregation/anthropic_claude-opus-4.6_20260414_110948/flower/custom_fl_aggregation.py", line 551, in <module>
    run_fl_simulation(args)
  File "/srv/home/bohanlyu/MLS-Bench/vendor/workspace/ml-federated-aggregation/anthropic_claude-opus-4.6_20260414_110948/flower/custom_fl_aggregation.py", line 497, in run_fl_simulation
    updated_state, n_samples, avg_loss = client_local_train(
  File "/srv/home/bohanlyu/MLS-Bench/vendor/workspace/ml-federated-aggregation/anthropic_claude-opus-4.6_20260414_110948/flower/custom_fl_aggregation.py", line 274, in client_l
AssistantStep 8submit
Tool Input
1{
2  "n": 2
3}
Tool ResultStep 8
[submit] Submitting result from test #2 as final.

### cifar10 (scripts/cifar10.sh)
Training metrics (last rounds):
TRAIN_METRICS round=180 avg_loss=0.0919 round_time=4.9s
TRAIN_METRICS round=185 avg_loss=0.0981 round_time=5.2s
TRAIN_METRICS round=190 avg_loss=0.0359 round_time=4.4s
TRAIN_METRICS round=195 avg_loss=0.0388 round_time=5.2s
TRAIN_METRICS round=200 avg_loss=0.0662 round_time=4.5s
Evaluation progress:
EVAL round=160 test_loss=1.5424 test_accuracy=0.6323 elapsed=710s
EVAL round=170 test_loss=1.6133 test_accuracy=0.6285 elapsed=765s
EVAL round=180 test_loss=1.5337 test_accuracy=0.6385 elapsed=810s
EVAL round=190 test_loss=1.3986 test_accuracy=0.6731 elapsed=859s
EVAL round=200 test_loss=1.6660 test_accuracy=0.6411 elapsed=910s
Final metrics (cifar10):
test_accuracy_cifar10: 0.6411
test_loss_cifar10: 1.6660
best_accuracy_cifar10: 0.6731

### femnist (scripts/femnist.sh)
Training metrics (last rounds):
TRAIN_METRICS round=180 avg_loss=0.0153 round_time=60.3s
TRAIN_METRICS round