diff --git a/claude_bottle/backend/docker/cred_proxy.py b/claude_bottle/backend/docker/cred_proxy.py
index 6da6fce..d0cfd69 100644
--- a/claude_bottle/backend/docker/cred_proxy.py
+++ b/claude_bottle/backend/docker/cred_proxy.py
@@ -10,6 +10,7 @@ import subprocess
 from pathlib import Path
 
 from ...cred_proxy import (
+    CRED_PROXY_HOSTNAME,
     CredProxy,
     CredProxyPlan,
     cred_proxy_resolve_token_values,
@@ -30,13 +31,6 @@ CRED_PROXY_DOCKERFILE = "Dockerfile.cred-proxy"
 # both reference it.
 CRED_PROXY_PORT = int(os.environ.get("CLAUDE_BOTTLE_CRED_PROXY_PORT", "9099"))
 
-# DNS name agents use to reach the sidecar. Attached as a
-# --network-alias on the internal docker network so the URL the
-# provisioner writes into the agent's environ is stable across
-# bottles (the container name carries the per-bottle slug; the alias
-# does not).
-CRED_PROXY_HOSTNAME = "cred-proxy"
-
 # In-container path the proxy server reads its route table from.
 # Pre-created in Dockerfile.cred-proxy so `docker cp` can drop the
 # file directly.
diff --git a/claude_bottle/cred_proxy.py b/claude_bottle/cred_proxy.py
index 79ee4e5..0856d85 100644
--- a/claude_bottle/cred_proxy.py
+++ b/claude_bottle/cred_proxy.py
@@ -31,6 +31,16 @@ from .log import die
 from .manifest import Bottle
 
 
+# DNS name agents use to reach the per-bottle cred-proxy sidecar.
+# Backend-agnostic by contract: every concrete backend (Docker today,
+# others later) attaches this name to its sidecar on the bottle's
+# internal network so the agent's manifest-driven URLs (`http://
+# cred-proxy:9099/...`) work without a backend-specific hostname.
+# pipelock's allowlist also references this when adding the
+# auto-allow entry for cred-proxy traffic from the agent.
+CRED_PROXY_HOSTNAME = "cred-proxy"
+
+
 @dataclass(frozen=True)
 class CredProxyRoute:
     """One resolved route on the cred-proxy sidecar. Maps a path
@@ -247,6 +257,7 @@ class CredProxy(ABC):
 
 
 __all__ = [
+    "CRED_PROXY_HOSTNAME",
     "CredProxy",
     "CredProxyPlan",
     "CredProxyRoute",
diff --git a/claude_bottle/pipelock.py b/claude_bottle/pipelock.py
index 52f5b23..67234ce 100644
--- a/claude_bottle/pipelock.py
+++ b/claude_bottle/pipelock.py
@@ -17,6 +17,7 @@ from dataclasses import dataclass
 from pathlib import Path
 from typing import cast
 
+from .cred_proxy import CRED_PROXY_HOSTNAME
 from .manifest import Bottle
 
 # Baked-in default allowlist for hosts Claude Code itself needs.
@@ -74,10 +75,17 @@ def pipelock_token_hosts(bottle: Bottle) -> list[str]:
 
 def pipelock_effective_allowlist(bottle: Bottle) -> list[str]:
     """Deduplicated union of: baked-in defaults, bottle.egress.allowlist,
-    and the cred-proxy upstream hosts derived from bottle.cred_proxy.routes.
-    Sorted for stability. Git upstreams declared in `bottle.git` do NOT
-    contribute here — git traffic flows through the per-agent git-gate
-    sidecar (PRD 0008), not pipelock."""
+    the cred-proxy upstream hosts derived from bottle.cred_proxy.routes,
+    and the cred-proxy sidecar's own hostname when any cred_proxy route
+    is declared. Sorted for stability. Git upstreams declared in
+    `bottle.git` do NOT contribute here — git traffic flows through the
+    per-agent git-gate sidecar (PRD 0008), not pipelock.
+
+    The cred-proxy hostname is auto-added because the agent's
+    HTTP_PROXY points at pipelock, so a manifest-driven URL like
+    `http://cred-proxy:9099/anthropic/...` arrives at pipelock as a
+    request for hostname `cred-proxy`. Without this auto-allow,
+    pipelock would 403 the request before it reached the sidecar."""
     seen: dict[str, None] = {}
     for h in DEFAULT_ALLOWLIST:
         seen.setdefault(h, None)
@@ -86,6 +94,8 @@ def pipelock_effective_allowlist(bottle: Bottle) -> list[str]:
             seen.setdefault(h, None)
     for h in pipelock_token_hosts(bottle):
         seen.setdefault(h, None)
+    if bottle.cred_proxy.routes:
+        seen.setdefault(CRED_PROXY_HOSTNAME, None)
     return sorted(seen.keys())
 
 
diff --git a/tests/unit/test_pipelock_allowlist.py b/tests/unit/test_pipelock_allowlist.py
index 29125aa..a10fae1 100644
--- a/tests/unit/test_pipelock_allowlist.py
+++ b/tests/unit/test_pipelock_allowlist.py
@@ -75,6 +75,22 @@ class TestAllowlistWithTokens(unittest.TestCase):
         self.assertIn("registry.npmjs.org", eff)
         self.assertIn("api.github.com", eff)
 
+    def test_cred_proxy_hostname_auto_added_when_routes_exist(self):
+        # The agent's HTTP_PROXY points at pipelock, so a request for
+        # http://cred-proxy:9099/... arrives at pipelock as a request
+        # for hostname `cred-proxy`. pipelock must allow it or the
+        # agent can't reach its own sidecar.
+        eff = pipelock_effective_allowlist(_bottle(_routes([
+            {"path": "/x/", "upstream": "https://x.example",
+             "auth_scheme": "Bearer", "token_ref": "T"},
+        ])))
+        self.assertIn("cred-proxy", eff)
+
+    def test_cred_proxy_hostname_NOT_added_when_no_routes(self):
+        # No cred-proxy sidecar, no auto-allow.
+        eff = pipelock_effective_allowlist(_bottle({}))
+        self.assertNotIn("cred-proxy", eff)
+
 
 class TestTlsPassthrough(unittest.TestCase):
     def test_default_includes_api_anthropic(self):