fix: CLI bugs - island list, output signature, GPU credentials, mining subcommand

- S05 Islands: edge.py list_islands now has name='list' for 'aitbc edge island list'
- S06 Market: output() now handles structured data (dict/list) by JSON-encoding
- S09 GPU: added safe_load_credentials() to gpu_marketplace.py and exchange_island.py
  with graceful FileNotFoundError handling and helpful error message
- S13 Mining: added 'list' subcommand to mining.py for listing active miners

cli/aitbc_cli/commands/edge.py

@@ -80,7 +80,7 @@ def leave(island_id: str):
         error(f"Error leaving island: {str(e)}")
 
 
-@island.command()
+@island.command(name='list')
 def list_islands():
     """List all islands"""
     try:

cli/aitbc_cli/commands/exchange_island.py

@@ -24,6 +24,16 @@ from aitbc import get_logger, AITBCHTTPClient, NetworkError
 logger = get_logger(__name__)
 
 
+def safe_load_credentials():
+    """Load island credentials with graceful error handling"""
+    try:
+        return load_island_credentials()
+    except FileNotFoundError as e:
+        error(f"Island credentials not found: {e}")
+        error("Run 'aitbc node island join' to join an island first")
+        return None
+
+
 # Supported trading pairs
 SUPPORTED_PAIRS = ['AIT/BTC', 'AIT/ETH']
 
@@ -47,7 +57,9 @@ def buy(ctx, ait_amount: float, quote_currency: str, max_price: Optional[float])
             raise click.Abort()
 
         # Load island credentials
-        credentials = load_island_credentials()
+        credentials = safe_load_credentials()
+        if not credentials:
+            return
         rpc_endpoint = get_rpc_endpoint()
         chain_id = get_chain_id()
         island_id = get_island_id()
@@ -144,7 +156,9 @@ def sell(ctx, ait_amount: float, quote_currency: str, min_price: Optional[float]
             raise click.Abort()
 
         # Load island credentials
-        credentials = load_island_credentials()
+        credentials = safe_load_credentials()
+        if not credentials:
+            return
         rpc_endpoint = get_rpc_endpoint()
         chain_id = get_chain_id()
         island_id = get_island_id()
@@ -232,7 +246,9 @@ def orderbook(ctx, pair: str, limit: int):
     """View the order book for a trading pair"""
     try:
         # Load island credentials
-        credentials = load_island_credentials()
+        credentials = safe_load_credentials()
+        if not credentials:
+            return
         rpc_endpoint = get_rpc_endpoint()
         island_id = get_island_id()
 
@@ -320,7 +336,9 @@ def rates(ctx):
     """View current exchange rates for AIT/BTC and AIT/ETH"""
     try:
         # Load island credentials
-        credentials = load_island_credentials()
+        credentials = safe_load_credentials()
+        if not credentials:
+            return
         rpc_endpoint = get_rpc_endpoint()
         island_id = get_island_id()
 
@@ -380,7 +398,9 @@ def orders(ctx, user: Optional[str], status: Optional[str], pair: Optional[str])
     """List exchange orders"""
     try:
         # Load island credentials
-        credentials = load_island_credentials()
+        credentials = safe_load_credentials()
+        if not credentials:
+            return
         rpc_endpoint = get_rpc_endpoint()
         island_id = get_island_id()
 
@@ -435,7 +455,9 @@ def cancel(ctx, order_id: str):
     """Cancel an exchange order"""
     try:
         # Load island credentials
-        credentials = load_island_credentials()
+        credentials = safe_load_credentials()
+        if not credentials:
+            return
         rpc_endpoint = get_rpc_endpoint()
         chain_id = get_chain_id()
         island_id = get_island_id()

cli/aitbc_cli/commands/gpu_marketplace.py

@@ -15,7 +15,7 @@ from typing import Optional, List
 from ..utils import output, error, success, info, warning
 from ..utils.island_credentials import (
     load_island_credentials, get_rpc_endpoint, get_chain_id,
-    get_island_id, get_island_name
+    get_island_id, get_island_name, validate_credentials
 )
 from ..config import get_config
 
@@ -26,6 +26,16 @@ from aitbc import get_logger, AITBCHTTPClient, NetworkError
 logger = get_logger(__name__)
 
 
+def safe_load_credentials():
+    """Load island credentials with graceful error handling"""
+    try:
+        return load_island_credentials()
+    except FileNotFoundError as e:
+        error(f"Island credentials not found: {e}")
+        error("Run 'aitbc node island join' to join an island first")
+        return None
+
+
 @click.group()
 def gpu():
     """GPU marketplace commands for bidding and offering GPU power"""
@@ -46,7 +56,9 @@ def offer(ctx, gpu_count: int, price_per_gpu: float, duration_hours: int, specs:
         config = get_config()
         
         # Load island credentials
-        credentials = load_island_credentials()
+        credentials = safe_load_credentials()
+        if not credentials:
+            return
         chain_id = get_chain_id()
         island_id = get_island_id()
 
@@ -149,7 +161,9 @@ def bid(ctx, gpu_count: int, max_price: float, duration_hours: int, specs: Optio
         config = get_config()
         
         # Load island credentials
-        credentials = load_island_credentials()
+        credentials = safe_load_credentials()
+        if not credentials:
+            return
         chain_id = get_chain_id()
         island_id = get_island_id()
 
@@ -250,7 +264,9 @@ def list(ctx, provider: Optional[str], status: Optional[str], type: str):
         config = get_config()
         
         # Load island credentials
-        credentials = load_island_credentials()
+        credentials = safe_load_credentials()
+        if not credentials:
+            return
         island_id = get_island_id()
 
         # Query GPU service for GPU marketplace transactions
@@ -322,7 +338,9 @@ def cancel(ctx, order_id: str):
         config = get_config()
         
         # Load island credentials
-        credentials = load_island_credentials()
+        credentials = safe_load_credentials()
+        if not credentials:
+            return
         chain_id = get_chain_id()
         island_id = get_island_id()
 
@@ -388,7 +406,9 @@ def accept(ctx, bid_id: str):
         config = get_config()
         
         # Load island credentials
-        credentials = load_island_credentials()
+        credentials = safe_load_credentials()
+        if not credentials:
+            return
         chain_id = get_chain_id()
         island_id = get_island_id()
 
@@ -451,7 +471,9 @@ def status(ctx, order_id: str):
         config = get_config()
         
         # Load island credentials
-        credentials = load_island_credentials()
+        credentials = safe_load_credentials()
+        if not credentials:
+            return
         island_id = get_island_id()
 
         # Query GPU service for the order
@@ -520,7 +542,9 @@ def match(ctx):
         config = get_config()
         
         # Load island credentials
-        credentials = load_island_credentials()
+        credentials = safe_load_credentials()
+        if not credentials:
+            return
         island_id = get_island_id()
 
         # Query GPU service for open offers and bids
@@ -612,7 +636,9 @@ def providers(ctx):
     """Query island members for GPU providers"""
     try:
         # Load island credentials
-        credentials = load_island_credentials()
+        credentials = safe_load_credentials()
+        if not credentials:
+            return
         island_id = get_island_id()
 
         # Load island members from credentials

cli/aitbc_cli/commands/mining.py

@@ -104,3 +104,21 @@ def status(rpc_url: Optional[str]):
         error(f"Error getting mining status: {e}")
     except Exception as e:
         error(f"Error: {e}")
+
+
+@mining.command(name='list')
+@click.option('--rpc-url', help='Blockchain RPC URL')
+def list_miners(rpc_url: Optional[str]):
+    """List active miners"""
+    if not rpc_url:
+        rpc_url = DEFAULT_RPC_URL
+
+    try:
+        http_client = AITBCHTTPClient(base_url=rpc_url, timeout=30)
+        result = http_client.get("/rpc/mining/miners")
+        success("Active miners:")
+        click.echo(json.dumps(result, indent=2))
+    except NetworkError as e:
+        error(f"Error listing miners: {e}")
+    except Exception as e:
+        error(f"Error: {e}")

cli/aitbc_cli/utils/__init__.py

@@ -16,8 +16,11 @@ from .wallet import decrypt_private_key
 from .blockchain import get_chain_info, get_network_status, get_blockchain_analytics
 
 
-def output(message: str, **kwargs):
-    """Print a regular output message"""
+def output(message, **kwargs):
+    """Print a regular output message (handles strings and structured data)"""
+    if not isinstance(message, str):
+        import json
+        message = json.dumps(message, indent=2)
     echo(message, **kwargs)