diff --git a/src/aioproxies/manager.py b/src/aioproxies/manager.py
index 6701092..99e350c 100644
--- a/src/aioproxies/manager.py
+++ b/src/aioproxies/manager.py
@@ -56,7 +56,7 @@ class AioProxies:
         self.session_len = session_len
         self.cooldown = cooldown
         self._shuffle = shuffle
-        self._static = parse(static) if static is not None else None
+        self._static = to_proxy(static) if static is not None else None
         self._proxies = self._dedupe([parse(p) for p in proxies]) if proxies is not None else []
         if self._proxies and shuffle:
             random.shuffle(self._proxies)
@@ -116,6 +116,17 @@ class AioProxies:
             return False
         return now >= timeout
 
+    @staticmethod
+    def _clear_stale_burn(state: Dict[str, object]) -> None:
+        """self-clear a lazily-expired timed burn's `burned` flag once found available
+
+        mirrors the lazy expiry already applied to `timeout` itself: a timed burn()
+        that has simply run out its clock should stop upgrading routine cooldown
+        fallthrough logs to warning, without requiring an explicit restore().
+        """
+        if state["timeout"] not in (None, 0, _DEAD):
+            state["burned"] = False
+
     def next(self, **fields: object) -> Proxy:
         """return the next proxy from the configured source
 
@@ -145,7 +156,7 @@ class AioProxies:
                 # a malformed template (e.g. an unmatched '{') makes str.format raise a
                 # bare ValueError - re-raise naming the cause so it isn't cryptic
                 raise ValueError(f"malformed proxy template {self.template!r}: {exc}") from exc
-            return parse(filled)
+            return to_proxy(filled)
         return self._next_from_list()
 
     def _next_from_list(self) -> Proxy:
@@ -158,9 +169,10 @@ class AioProxies:
         fine: List[int] = []
         for offset in range(count):
             idx = (self._index + offset) % count
-            timeout = self._state[self._proxies[idx].key()]["timeout"]
-            if self._available(timeout, now):
+            state = self._state[self._proxies[idx].key()]
+            if self._available(state["timeout"], now):
                 fine.append(idx)
+                self._clear_stale_burn(state)
 
         if fine:
             chosen = fine[0]
@@ -248,8 +260,11 @@ class AioProxies:
         key = canonical_key(proxy)
         if key not in self._state:
             return False
-        timeout = self._state[key]["timeout"]
-        return not self._available(timeout, time.time())
+        state = self._state[key]
+        available = self._available(state["timeout"], time.time())
+        if available:
+            self._clear_stale_burn(state)
+        return not available
 
     def stats(self) -> List[Dict[str, object]]:
         """per-proxy usage + state snapshot (list sources only, else empty)
@@ -293,11 +308,15 @@ class AioProxies:
         keep_state=False (default) wipes all per-proxy state (fresh batch).
         keep_state=True preserves uses/timeout for proxies whose canonical key
         survives the swap; new proxies start clean, dropped ones are forgotten.
-        resets the rotation index and honors the manager's shuffle setting.
+        resets the rotation index and honors the manager's shuffle setting. raises
+        ValueError on an empty list, matching the constructor's guard - use remove()
+        to drop proxies one at a time if you actually want a smaller pool.
         """
         if not self._is_list_source():
             self._warn_non_list("replace()")
             return
+        if len(proxies) == 0:
+            raise ValueError("proxies list is empty; provide at least one proxy")
         old_state = self._state
         incoming = [to_proxy(p) for p in proxies]
         if self._shuffle:
diff --git a/src/aioproxies/net.py b/src/aioproxies/net.py
index 195dc3a..a5f3da4 100644
--- a/src/aioproxies/net.py
+++ b/src/aioproxies/net.py
@@ -7,7 +7,7 @@ calling a function without it raises a clear error.
 import logging
 from typing import Optional, Union
 
-from .proxy import Proxy, parse
+from .proxy import Proxy, to_proxy
 
 log = logging.getLogger(__name__)
 
@@ -32,7 +32,7 @@ async def current_ip(
     """
     if not _HAVE_AIOHTTP:
         raise RuntimeError(_MISSING)
-    p = parse(proxy)
+    p = to_proxy(proxy)
     t = aiohttp.ClientTimeout(total=timeout)
     try:
         async with aiohttp.ClientSession(timeout=t) as session:
diff --git a/src/aioproxies/proxy.py b/src/aioproxies/proxy.py
index 7eb3588..30b4f4c 100644
--- a/src/aioproxies/proxy.py
+++ b/src/aioproxies/proxy.py
@@ -97,12 +97,15 @@ class Proxy:
 
 
 def parse(spec: Union[str, Proxy]) -> Proxy:
-    """parse a proxy spec into a Proxy
+    """parse a colon-delimited proxy spec into a Proxy
 
     accepts an existing Proxy (returned as-is) or a colon-delimited string in
     `host:port` or `host:port:user:pass` form. the 4-part form splits on the first
-    three colons only, so a password may itself contain colons. raises ValueError
-    on anything else rather than guessing.
+    three colons only, so a password may itself contain colons. this is spec-string
+    only - it does not understand url shapes (`scheme://user:pass@host:port`); a
+    url has 3+ colons and would be misparsed as a 4-part spec rather than rejected.
+    use `to_proxy()` for url / dict / spec input, or anywhere the shape isn't
+    guaranteed to be a bare spec string.
     """
     if isinstance(spec, Proxy):
         return spec