diff --git a/src/forge/proxy/__main__.py b/src/forge/proxy/__main__.py
index 055bae0..4ef0688 100644
--- a/src/forge/proxy/__main__.py
+++ b/src/forge/proxy/__main__.py
@@ -67,6 +67,12 @@ def main() -> None:
     parser.add_argument("--serialize", action="store_true", default=None, help="Force request serialization")
     parser.add_argument("--no-serialize", action="store_true", help="Disable request serialization")
     parser.add_argument("--max-retries", type=int, default=3, help="Max retries per request (default: 3)")
+    parser.add_argument(
+        "--backend-timeout",
+        type=float,
+        default=300.0,
+        help="Backend response timeout in seconds (default: 300)",
+    )
     parser.add_argument("--no-rescue", action="store_true", help="Disable rescue parsing")
     parser.add_argument("--verbose", "-v", action="store_true", help="Verbose logging")
 
@@ -104,6 +110,7 @@ def main() -> None:
         rescue_enabled=not args.no_rescue,
         mode=args.mode,
         backend_protocol=args.backend_protocol,
+        backend_timeout=args.backend_timeout,
     )
 
     def _shutdown(sig: int, _frame: object) -> None:
diff --git a/src/forge/proxy/proxy.py b/src/forge/proxy/proxy.py
index d534411..a4d3c8d 100644
--- a/src/forge/proxy/proxy.py
+++ b/src/forge/proxy/proxy.py
@@ -9,6 +9,7 @@
 
 import asyncio
 import logging
+import math
 import threading
 from pathlib import Path
 from typing import Literal
@@ -68,6 +69,7 @@ def __init__(
         rescue_enabled: bool = True,
         mode: Literal["native", "prompt"] = "native",
         backend_protocol: Literal["openai", "anthropic"] = "openai",
+        backend_timeout: float = 300.0,
     ) -> None:
         """
         Args:
@@ -101,6 +103,8 @@ def __init__(
                 for Anthropic-shape downstreams (the official Anthropic API,
                 LiteLLM's /v1/messages, a self-hosted Anthropic proxy).
                 Only meaningful in external mode; ignored in managed mode.
+            backend_timeout: Timeout in seconds for requests from the proxy to
+                the downstream backend.
         """
         if backend_url is None and backend is None:
             raise ValueError("Provide either backend_url (external) or backend (managed)")
@@ -126,6 +130,8 @@ def __init__(
                 "backend='vllm' parses tool calls server-side (native only); "
                 "mode='prompt' is not applicable."
             )
+        if not math.isfinite(backend_timeout) or backend_timeout <= 0:
+            raise ValueError("backend_timeout must be a finite value greater than 0")
         # Managed mode: each backend requires its own identity field. Fail
         # fast at construction with a clear message (mirrors setup_backend).
         if backend_url is None:
@@ -151,6 +157,7 @@ def __init__(
         self._rescue_enabled = rescue_enabled
         self._mode = mode
         self._backend_protocol = backend_protocol
+        self._backend_timeout = backend_timeout
 
         # Auto-detect serialization: managed (no external url) = single local
         # GPU = serialize. External callers manage their own concurrency.
@@ -257,6 +264,7 @@ async def _setup_external(self) -> tuple[LLMClient, ContextManager]:
             client: LLMClient = AnthropicClient(
                 model=self._model or "claude",
                 base_url=self._backend_url.rstrip("/"),
+                timeout=self._backend_timeout,
             )
             # Anthropic models report a known context length; keep the legacy
             # 8192 fallback rather than failing the well-behaved Path-1 case.
@@ -273,7 +281,11 @@ async def _setup_external(self) -> tuple[LLMClient, ContextManager]:
             base = base + "/v1"
 
         if self._backend == "vllm":
-            client = VLLMClient(model_path="default", base_url=base)
+            client = VLLMClient(
+                model_path="default",
+                base_url=base,
+                timeout=self._backend_timeout,
+            )
             # Unlike llama.cpp, vLLM validates the wire `model` field against
             # its --served-model-name aliases (404 on mismatch). External mode
             # has no model path to send, so discover the served identity from
@@ -299,6 +311,7 @@ async def _setup_external(self) -> tuple[LLMClient, ContextManager]:
                 gguf_path=self._model or "default",
                 base_url=base,
                 mode=self._mode,
+                timeout=self._backend_timeout,
             )
 
         if self._budget_tokens is not None:
@@ -348,18 +361,23 @@ def _build_managed_client(self) -> LLMClient:
         base_url = f"http://localhost:{self._backend_port}/v1"
         if self._backend == "ollama":
             assert self._model is not None
-            return OllamaClient(model=self._model)
+            return OllamaClient(
+                model=self._model,
+                timeout=self._backend_timeout,
+            )
         if self._backend in ("llamaserver", "llamafile"):
             return LlamafileClient(
                 gguf_path=self._gguf or "default",
                 base_url=base_url,
                 mode=self._mode,
+                timeout=self._backend_timeout,
             )
         if self._backend == "vllm":
             assert self._model_path is not None
             return VLLMClient(
                 model_path=self._model_path,
                 base_url=base_url,
+                timeout=self._backend_timeout,
             )
         raise ValueError(f"unsupported backend: {self._backend!r}")
 
diff --git a/tests/unit/test_proxy_path1.py b/tests/unit/test_proxy_path1.py
index 5ba902b..6a1d591 100644
--- a/tests/unit/test_proxy_path1.py
+++ b/tests/unit/test_proxy_path1.py
@@ -12,7 +12,7 @@
 
 from __future__ import annotations
 
-from unittest.mock import AsyncMock, MagicMock
+from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
 
@@ -55,6 +55,28 @@ def test_openai_default_unchanged(self):
         )
         assert proxy._backend_protocol == "openai"
 
+    @pytest.mark.asyncio
+    async def test_anthropic_external_receives_backend_timeout(self):
+        proxy = ProxyServer(
+            backend_url="http://localhost:8080",
+            backend_protocol="anthropic",
+            backend_timeout=1800.0,
+        )
+        with patch("forge.clients.anthropic.AnthropicClient") as mock_client_cls:
+            mock_client = MagicMock()
+            mock_client.get_context_length = AsyncMock(return_value=200000)
+            mock_client_cls.return_value = mock_client
+
+            client, ctx = await proxy._setup_external()
+
+        assert client is mock_client
+        assert ctx.budget_tokens == 200000
+        mock_client_cls.assert_called_once_with(
+            model="claude",
+            base_url="http://localhost:8080",
+            timeout=1800.0,
+        )
+
 
 # ── AnthropicClient verbatim path ────────────────────────────
 
diff --git a/tests/unit/test_proxy_proxy.py b/tests/unit/test_proxy_proxy.py
index 7cd8e32..56f8c34 100644
--- a/tests/unit/test_proxy_proxy.py
+++ b/tests/unit/test_proxy_proxy.py
@@ -62,6 +62,15 @@ def test_managed_vllm_requires_model_path(self) -> None:
         with pytest.raises(ValueError, match="requires model_path"):
             ProxyServer(backend="vllm")
 
+    @pytest.mark.parametrize("backend_timeout", [0, -1, float("nan"), float("inf")])
+    def test_backend_timeout_must_be_finite_and_positive(
+        self, backend_timeout: float,
+    ) -> None:
+        with pytest.raises(
+            ValueError, match="backend_timeout must be a finite value greater than 0",
+        ):
+            ProxyServer(backend_url="http://x:8000", backend_timeout=backend_timeout)
+
     def test_managed_ok(self) -> None:
         ProxyServer(backend="llamaserver", gguf="m.gguf")
         ProxyServer(backend="llamafile", gguf="m.gguf")
@@ -75,6 +84,11 @@ def test_external_ok(self) -> None:
         proxy2 = ProxyServer(backend_url="http://x:8000", backend="vllm")
         assert proxy2._backend == "vllm"
 
+    def test_backend_timeout_default_and_override(self) -> None:
+        assert ProxyServer(backend_url="http://x:8000")._backend_timeout == 300.0
+        proxy = ProxyServer(backend_url="http://x:8000", backend_timeout=1800.0)
+        assert proxy._backend_timeout == 1800.0
+
     # Serialize auto-detection: managed (no url) serializes, external does not.
     def test_serialize_auto_managed_true(self) -> None:
         assert ProxyServer(backend="vllm", model_path="/m")._serialize is True
@@ -92,10 +106,15 @@ class TestSetupExternal:
 
     @pytest.mark.asyncio
     async def test_llamaserver_uses_llamafile_client(self) -> None:
-        proxy = ProxyServer(backend_url="http://localhost:8080", budget_tokens=8192)
+        proxy = ProxyServer(
+            backend_url="http://localhost:8080",
+            budget_tokens=8192,
+            backend_timeout=1800.0,
+        )
         client, ctx = await proxy._setup_external()
         assert isinstance(client, LlamafileClient)
         assert client.base_url == "http://localhost:8080/v1"
+        assert client._http.timeout.read == 1800.0
         assert ctx.budget_tokens == 8192
 
     @pytest.mark.asyncio
@@ -109,7 +128,10 @@ async def test_explicit_llamafile_backend_uses_llamafile_client(self) -> None:
     @pytest.mark.asyncio
     async def test_vllm_uses_vllm_client(self) -> None:
         proxy = ProxyServer(
-            backend_url="http://localhost:8000", backend="vllm", budget_tokens=8192,
+            backend_url="http://localhost:8000",
+            backend="vllm",
+            budget_tokens=8192,
+            backend_timeout=1800.0,
         )
         with patch.object(
             VLLMClient, "get_served_model_name", new_callable=AsyncMock, return_value=None,
@@ -117,6 +139,7 @@ async def test_vllm_uses_vllm_client(self) -> None:
             client, ctx = await proxy._setup_external()
         assert isinstance(client, VLLMClient)
         assert client.base_url == "http://localhost:8000/v1"
+        assert client._http.timeout.read == 1800.0
         assert ctx.budget_tokens == 8192
 
     @pytest.mark.asyncio
@@ -186,6 +209,7 @@ async def test_llamaserver_wiring(self) -> None:
             backend_port=8080,
             budget_mode=BudgetMode.FORGE_FAST,
             extra_flags=["-ngl", "99"],
+            backend_timeout=1800.0,
         )
         mock_ctx = ContextManager.__new__(ContextManager)
         mock_ctx.budget_tokens = 16384
@@ -199,6 +223,7 @@ async def test_llamaserver_wiring(self) -> None:
 
         assert isinstance(client, LlamafileClient)
         assert client.base_url == "http://localhost:8080/v1"
+        assert client._http.timeout.read == 1800.0
         kwargs = mock_setup.await_args.kwargs
         assert kwargs["backend"] == "llamaserver"
         assert kwargs["gguf_path"] == "/models/x.gguf"
@@ -217,6 +242,7 @@ async def test_vllm_wiring(self) -> None:
         proxy = ProxyServer(
             backend="vllm", model_path="/models/awq", backend_port=8000,
             budget_tokens=113000, budget_mode=BudgetMode.MANUAL,
+            backend_timeout=1800.0,
         )
         mock_ctx = ContextManager.__new__(ContextManager)
         mock_ctx.budget_tokens = 113000
@@ -228,6 +254,7 @@ async def test_vllm_wiring(self) -> None:
 
         assert isinstance(client, VLLMClient)
         assert client.base_url == "http://localhost:8000/v1"
+        assert client._http.timeout.read == 1800.0
         kwargs = mock_setup.await_args.kwargs
         assert kwargs["backend"] == "vllm"
         assert kwargs["model_path"] == "/models/awq"
@@ -238,7 +265,11 @@ async def test_vllm_wiring(self) -> None:
 
     @pytest.mark.asyncio
     async def test_ollama_wiring(self) -> None:
-        proxy = ProxyServer(backend="ollama", model="ministral-3:14b")
+        proxy = ProxyServer(
+            backend="ollama",
+            model="ministral-3:14b",
+            backend_timeout=1800.0,
+        )
         mock_ctx = ContextManager.__new__(ContextManager)
         mock_ctx.budget_tokens = 4096
         with patch(
@@ -247,6 +278,7 @@ async def test_ollama_wiring(self) -> None:
         ) as mock_setup:
             client, _ = await proxy._setup_managed()
         assert isinstance(client, OllamaClient)
+        assert client._http.timeout.read == 1800.0
         kwargs = mock_setup.await_args.kwargs
         assert kwargs["backend"] == "ollama"
         assert kwargs["model"] == "ministral-3:14b"