feat(claude): add forward_host_credentials support

Reads the host's Claude OAuth session key from ~/.claude.json at launch
and forwards it only to the egress sidecar (never to the agent), placing
a placeholder CLAUDE_CODE_OAUTH_TOKEN in the agent env so Claude Code
starts without seeing the real credential.

Mirrors the existing Codex forward_host_credentials flow (PRD 0029).
Adds claude_auth.py to extract and validate the sessionKey, a
CLAUDE_HOST_CREDENTIAL_TOKEN_REF constant in egress.py, and updates
manifest_agent.py to allow the flag for both 'codex' and 'claude'
templates. Also adds a mutual-exclusion check that rejects setting
both auth_token and forward_host_credentials together.

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

tests/unit/test_agent_provider.py

@@ -9,11 +9,15 @@ import unittest
 from pathlib import Path
 
 from bot_bottle.agent_provider import (
+    CLAUDE_HOST_CREDENTIAL_HOSTS,
     CODEX_HOST_CREDENTIAL_HOSTS,
     build_agent_provision_plan,
     prompt_args,
 )
-from bot_bottle.egress import CODEX_HOST_CREDENTIAL_TOKEN_REF
+from bot_bottle.egress import (
+    CLAUDE_HOST_CREDENTIAL_TOKEN_REF,
+    CODEX_HOST_CREDENTIAL_TOKEN_REF,
+)
 
 
 def _jwt(exp: int) -> str:
@@ -289,6 +293,65 @@ class TestAgentProviderRuntime(unittest.TestCase):
             )
         self.assertEqual({}, plan.provisioned_env)
 
+    def test_claude_forward_host_credentials_populates_egress_route(self):
+        session_key = "sk-ant-oat01-test-key"
+        with tempfile.TemporaryDirectory(prefix="bb-provider.") as tmp:
+            home = Path(tmp) / "host-claude"
+            home.mkdir()
+            (home / ".claude.json").write_text(json.dumps({
+                "oauthAccount": {"sessionKey": session_key},
+            }))
+            plan = build_agent_provision_plan(
+                template="claude",
+                dockerfile="",
+                state_dir=Path(tmp),
+                instance_name="bot-bottle-test",
+                prompt_file=Path(tmp) / "prompt.txt",
+                forward_host_credentials=True,
+                host_env={"HOME": str(home)},
+            )
+        self.assertEqual(1, len(plan.egress_routes))
+        route = plan.egress_routes[0]
+        self.assertIn(route.host, CLAUDE_HOST_CREDENTIAL_HOSTS)
+        self.assertEqual("Bearer", route.auth_scheme)
+        self.assertEqual(CLAUDE_HOST_CREDENTIAL_TOKEN_REF, route.token_ref)
+        self.assertEqual("egress-placeholder", plan.env_vars["CLAUDE_CODE_OAUTH_TOKEN"])
+        self.assertEqual(frozenset({"CLAUDE_CODE_OAUTH_TOKEN"}), plan.hidden_env_names)
+
+    def test_claude_forward_host_credentials_populates_provisioned_env(self):
+        session_key = "sk-ant-oat01-test-key"
+        with tempfile.TemporaryDirectory(prefix="bb-provider.") as tmp:
+            home = Path(tmp) / "host-claude"
+            home.mkdir()
+            (home / ".claude.json").write_text(json.dumps({
+                "oauthAccount": {"sessionKey": session_key},
+            }))
+            plan = build_agent_provision_plan(
+                template="claude",
+                dockerfile="",
+                state_dir=Path(tmp),
+                instance_name="bot-bottle-test",
+                prompt_file=Path(tmp) / "prompt.txt",
+                forward_host_credentials=True,
+                host_env={"HOME": str(home)},
+            )
+        self.assertEqual(
+            {CLAUDE_HOST_CREDENTIAL_TOKEN_REF: session_key},
+            plan.provisioned_env,
+        )
+
+    def test_claude_without_forward_host_credentials_has_empty_provisioned_env(self):
+        with tempfile.TemporaryDirectory(prefix="bb-provider.") as tmp:
+            plan = build_agent_provision_plan(
+                template="claude",
+                dockerfile="",
+                state_dir=Path(tmp),
+                instance_name="bot-bottle-test",
+                prompt_file=Path(tmp) / "prompt.txt",
+                forward_host_credentials=False,
+            )
+        self.assertEqual({}, plan.provisioned_env)
+
     def test_pi_plan_writes_default_ollama_models(self):
         with tempfile.TemporaryDirectory(prefix="bb-provider.") as tmp:
             plan = build_agent_provision_plan(

tests/unit/test_contrib_claude_auth.py

@@ -0,0 +1,106 @@
+"""Unit: host Claude auth extraction."""
+
+from __future__ import annotations
+
+import json
+import tempfile
+import unittest
+from datetime import datetime, timezone
+from pathlib import Path
+
+from bot_bottle.contrib.claude.claude_auth import (
+    claude_auth_path,
+    claude_host_access_token,
+)
+from bot_bottle.log import Die
+
+
+class TestClaudeHostAccessToken(unittest.TestCase):
+    def setUp(self):
+        self.tmp = tempfile.TemporaryDirectory(prefix="bb-claude-auth.")
+        self.home = Path(self.tmp.name)
+        self.auth_path = self.home / ".claude.json"
+
+    def tearDown(self):
+        self.tmp.cleanup()
+
+    def _write(self, payload: dict) -> None:  # type: ignore
+        self.auth_path.write_text(json.dumps(payload))
+
+    def test_auth_path_uses_home_env(self):
+        self.assertEqual(
+            self.auth_path,
+            claude_auth_path({"HOME": str(self.home)}),
+        )
+
+    def test_returns_session_key(self):
+        key = "sk-ant-oat01-real-key"
+        self._write({"oauthAccount": {"sessionKey": key}})
+        out = claude_host_access_token({"HOME": str(self.home)})
+        self.assertEqual(key, out)
+
+    def test_missing_auth_file_dies(self):
+        with self.assertRaises(Die):
+            claude_host_access_token({"HOME": str(self.home)})
+
+    def test_missing_oauth_account_dies(self):
+        self._write({"hasCompletedOnboarding": True})
+        with self.assertRaises(Die):
+            claude_host_access_token({"HOME": str(self.home)})
+
+    def test_missing_session_key_dies(self):
+        self._write({"oauthAccount": {"expiresAt": 2000000000}})
+        with self.assertRaises(Die):
+            claude_host_access_token({"HOME": str(self.home)})
+
+    def test_empty_session_key_dies(self):
+        self._write({"oauthAccount": {"sessionKey": ""}})
+        with self.assertRaises(Die):
+            claude_host_access_token({"HOME": str(self.home)})
+
+    def test_expired_token_dies(self):
+        self._write({
+            "oauthAccount": {
+                "sessionKey": "sk-ant-oat01-x",
+                "expiresAt": 1000,
+            },
+        })
+        with self.assertRaises(Die):
+            claude_host_access_token(
+                {"HOME": str(self.home)},
+                now=datetime(2026, 1, 1, tzinfo=timezone.utc),
+            )
+
+    def test_future_expiry_is_accepted(self):
+        key = "sk-ant-oat01-y"
+        self._write({
+            "oauthAccount": {
+                "sessionKey": key,
+                "expiresAt": 2000000000,
+            },
+        })
+        out = claude_host_access_token(
+            {"HOME": str(self.home)},
+            now=datetime(2026, 1, 1, tzinfo=timezone.utc),
+        )
+        self.assertEqual(key, out)
+
+    def test_absent_expiry_field_is_accepted(self):
+        key = "sk-ant-oat01-z"
+        self._write({"oauthAccount": {"sessionKey": key}})
+        out = claude_host_access_token({"HOME": str(self.home)})
+        self.assertEqual(key, out)
+
+    def test_non_json_file_dies(self):
+        self.auth_path.write_text("not json {{{")
+        with self.assertRaises(Die):
+            claude_host_access_token({"HOME": str(self.home)})
+
+    def test_json_array_root_dies(self):
+        self.auth_path.write_text("[]")
+        with self.assertRaises(Die):
+            claude_host_access_token({"HOME": str(self.home)})
+
+
+if __name__ == "__main__":
+    unittest.main()

tests/unit/test_manifest_egress.py

@@ -80,11 +80,19 @@ class TestAgentProviderHostCredentials(unittest.TestCase):
                 "forward_host_credentials": "yes",
             })
 
-    def test_forward_host_credentials_rejected_for_claude(self):
+    def test_forward_host_credentials_allowed_for_claude(self):
+        b = _provider_config_bottle({
+            "template": "claude",
+            "forward_host_credentials": True,
+        })
+        self.assertTrue(b.agent_provider.forward_host_credentials)
+
+    def test_forward_host_credentials_and_auth_token_rejected_together(self):
         with self.assertRaises(ManifestError):
             _provider_config_bottle({
                 "template": "claude",
                 "forward_host_credentials": True,
+                "auth_token": "SOME_TOKEN",
             })
 
     def test_auth_token_defaults_empty(self):

tests/unit/test_manifest_validation.py

@@ -82,10 +82,22 @@ class TestAgentProviderValidation(unittest.TestCase):
                 "b", {"forward_host_credentials": True, "template": "weird"}
             )
 
-    def test_forward_creds_non_codex_template(self) -> None:
+    def test_forward_creds_pi_template_rejected(self) -> None:
         with self.assertRaises(ManifestError):
             ManifestAgentProvider.from_dict(
-                "b", {"forward_host_credentials": True, "template": "claude"}
+                "b", {"forward_host_credentials": True, "template": "pi"}
+            )
+
+    def test_forward_creds_claude_allowed(self) -> None:
+        p = ManifestAgentProvider.from_dict(
+            "b", {"forward_host_credentials": True, "template": "claude"}
+        )
+        self.assertTrue(p.forward_host_credentials)
+
+    def test_forward_creds_and_auth_token_rejected(self) -> None:
+        with self.assertRaises(ManifestError):
+            ManifestAgentProvider.from_dict(
+                "b", {"forward_host_credentials": True, "auth_token": "T", "template": "claude"}
             )
 
     def test_valid_claude_auth_token(self) -> None: