fix: iteration race, NID bounds check, and DRY delay parsing

gossip: _poll_loop_once iterated self.rids directly while _discover_rids
could append to it from the same call — replaced with list(self.rids)
snapshot to avoid RuntimeError on concurrent modification.

gossip: _on_announce was missing the nid_len bounds clamp that bridge.py
has, allowing a malformed truncated packet to slice beyond available bytes.
Now consistent with bridge.py: nid_len = min(nid_len, available).

cli: announce_retry_delays string→tuple parsing was copy-pasted three times
across cmd_gossip, cmd_seed, and cmd_bridge. Extracted to _parse_delays().
cmd_seed now validates delays before starting any processes so it never
needs to stop a running seed just to report a bad argument.

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

src/radicle_reticulum/cli.py

@@ -49,6 +49,14 @@ def detect_radicle_nid() -> Optional[str]:
         return None
 
 
+def _parse_delays(s: str) -> Tuple[int, ...]:
+    try:
+        return tuple(int(x.strip()) for x in s.split(",") if x.strip())
+    except ValueError:
+        print("Error: --announce-retry-delays must be comma-separated integers.", file=sys.stderr)
+        sys.exit(1)
+
+
 def on_peer_discovered(peer: PeerInfo):
     """Callback when a new peer is discovered."""
     print(f"[+] Discovered peer: {peer.identity.did}")
@@ -257,13 +265,7 @@ def cmd_gossip(args):
     if nid:
         print(f"Local NID: {nid}")
 
-    try:
-        announce_retry_delays = tuple(
-            int(x.strip()) for x in args.announce_retry_delays.split(",") if x.strip()
-        )
-    except ValueError:
-        print("Error: --announce-retry-delays must be comma-separated integers.", file=sys.stderr)
-        sys.exit(1)
+    announce_retry_delays = _parse_delays(args.announce_retry_delays)
 
     relay = GossipRelay(
         identity=identity,
@@ -318,6 +320,9 @@ def cmd_seed(args):
     """Start a dedicated seed radicle-node, bridge, and gossip relay."""
     seed_home = Path(args.seed_home)
 
+    # Validate args before starting any processes
+    announce_retry_delays = _parse_delays(args.announce_retry_delays)
+
     seed = SeedNode(seed_home=seed_home, port=args.seed_port)
 
     # First-time setup: guide the user
@@ -345,19 +350,9 @@ def cmd_seed(args):
         seed.stop()
         sys.exit(1)
 
-    # Start bridge pointing at the seed
     identity = RadicleIdentity.load_or_generate(args.identity)
     _print_identity_info(args.identity)
 
-    try:
-        announce_retry_delays = tuple(
-            int(x.strip()) for x in args.announce_retry_delays.split(",") if x.strip()
-        )
-    except ValueError:
-        print("Error: --announce-retry-delays must be comma-separated integers.", file=sys.stderr)
-        seed.stop()
-        sys.exit(1)
-
     bridge = RadicleBridge(
         identity=identity,
         listen_port=args.bridge_port,
@@ -452,13 +447,7 @@ def cmd_bridge(args):
     auto_connect = not args.no_auto_connect and not args.connect
     auto_seed = not args.no_auto_seed
 
-    try:
-        announce_retry_delays = tuple(
-            int(x.strip()) for x in args.announce_retry_delays.split(",") if x.strip()
-        )
-    except ValueError:
-        print("Error: --announce-retry-delays must be comma-separated integers, e.g. 5,15,30", file=sys.stderr)
-        sys.exit(1)
+    announce_retry_delays = _parse_delays(args.announce_retry_delays)
 
     bridge = RadicleBridge(
         identity=identity,

src/radicle_reticulum/gossip.py

@@ -261,7 +261,7 @@ class GossipRelay:
         if self.auto_discover:
             self._discover_rids()
 
-        for rid in self.rids:
+        for rid in list(self.rids):  # snapshot: _discover_rids may append mid-iteration
             try:
                 refs = _read_refs(self.storage, rid)
                 with self._refs_lock:
@@ -414,8 +414,9 @@ class GossipRelay:
             try:
                 offset = len(GOSSIP_MAGIC)
                 nid_len = struct.unpack("!H", app_data[offset:offset + 2])[0]
-                raw = app_data[offset + 2: offset + 2 + nid_len]
-                radicle_nid = raw.decode() or None
+                offset += 2
+                nid_len = min(nid_len, len(app_data) - offset)
+                radicle_nid = app_data[offset:offset + nid_len].decode() or None
             except Exception:
                 pass