diff --git a/agent/anthropic_adapter.py b/agent/anthropic_adapter.py
index 7a37fc414..6c22b9912 100644
--- a/agent/anthropic_adapter.py
+++ b/agent/anthropic_adapter.py
@@ -14,6 +14,8 @@ import copy
 import json
 import logging
 import os
+import platform
+import subprocess
 from pathlib import Path
 
 from hermes_constants import get_hermes_home
@@ -465,8 +467,72 @@ def build_anthropic_bedrock_client(region: str):
     )
 
 
+def _read_claude_code_credentials_from_keychain() -> Optional[Dict[str, Any]]:
+    """Read Claude Code OAuth credentials from the macOS Keychain.
+
+    Claude Code >=2.1.114 stores credentials in the macOS Keychain under the
+    service name "Claude Code-credentials" rather than (or in addition to)
+    the JSON file at ~/.claude/.credentials.json.
+
+    The password field contains a JSON string with the same claudeAiOauth
+    structure as the JSON file.
+
+    Returns dict with {accessToken, refreshToken?, expiresAt?} or None.
+    """
+    import platform
+    import subprocess
+
+    if platform.system() != "Darwin":
+        return None
+
+    try:
+        # Read the "Claude Code-credentials" generic password entry
+        result = subprocess.run(
+            ["security", "find-generic-password",
+             "-s", "Claude Code-credentials",
+             "-w"],
+            capture_output=True,
+            text=True,
+            timeout=5,
+        )
+    except (OSError, subprocess.TimeoutExpired):
+        logger.debug("Keychain: security command not available or timed out")
+        return None
+
+    if result.returncode != 0:
+        logger.debug("Keychain: no entry found for 'Claude Code-credentials'")
+        return None
+
+    raw = result.stdout.strip()
+    if not raw:
+        return None
+
+    try:
+        data = json.loads(raw)
+    except json.JSONDecodeError:
+        logger.debug("Keychain: credentials payload is not valid JSON")
+        return None
+
+    oauth_data = data.get("claudeAiOauth")
+    if oauth_data and isinstance(oauth_data, dict):
+        access_token = oauth_data.get("accessToken", "")
+        if access_token:
+            return {
+                "accessToken": access_token,
+                "refreshToken": oauth_data.get("refreshToken", ""),
+                "expiresAt": oauth_data.get("expiresAt", 0),
+                "source": "macos_keychain",
+            }
+
+    return None
+
+
 def read_claude_code_credentials() -> Optional[Dict[str, Any]]:
-    """Read refreshable Claude Code OAuth credentials from ~/.claude/.credentials.json.
+    """Read refreshable Claude Code OAuth credentials.
+
+    Checks two sources in order:
+      1. macOS Keychain (Darwin only) — "Claude Code-credentials" entry
+      2. ~/.claude/.credentials.json file
 
     This intentionally excludes ~/.claude.json primaryApiKey. Opencode's
     subscription flow is OAuth/setup-token based with refreshable credentials,
@@ -475,6 +541,12 @@ def read_claude_code_credentials() -> Optional[Dict[str, Any]]:
 
     Returns dict with {accessToken, refreshToken?, expiresAt?} or None.
     """
+    # Try macOS Keychain first (covers Claude Code >=2.1.114)
+    kc_creds = _read_claude_code_credentials_from_keychain()
+    if kc_creds:
+        return kc_creds
+
+    # Fall back to JSON file
     cred_path = Path.home() / ".claude" / ".credentials.json"
     if cred_path.exists():
         try:
diff --git a/hermes_cli/main.py b/hermes_cli/main.py
index c07b327e0..897a6c3cd 100644
--- a/hermes_cli/main.py
+++ b/hermes_cli/main.py
@@ -4316,6 +4316,8 @@ def _model_flow_anthropic(config, current_model=""):
         from agent.anthropic_adapter import (
             read_claude_code_credentials,
             is_claude_code_token_valid,
+            _is_oauth_token,
+            _resolve_claude_code_token_from_credentials,
         )
 
         cc_creds = read_claude_code_credentials()
@@ -4324,7 +4326,14 @@ def _model_flow_anthropic(config, current_model=""):
     except Exception:
         pass
 
-    has_creds = bool(existing_key) or cc_available
+    # Stale-OAuth guard: if the only existing cred is an expired OAuth token
+    # (no valid cc_creds to fall back on), treat it as missing so the re-auth
+    # path is offered instead of silently accepting a broken token.
+    existing_is_stale_oauth = False
+    if existing_key and _is_oauth_token(existing_key) and not cc_available:
+        existing_is_stale_oauth = True
+
+    has_creds = (bool(existing_key) and not existing_is_stale_oauth) or cc_available
     needs_auth = not has_creds
 
     if has_creds:
diff --git a/tests/agent/test_anthropic_keychain.py b/tests/agent/test_anthropic_keychain.py
new file mode 100644
index 000000000..c0f9c7718
--- /dev/null
+++ b/tests/agent/test_anthropic_keychain.py
@@ -0,0 +1,165 @@
+"""Tests for Bug #12905 fixes in agent/anthropic_adapter.py — macOS Keychain support."""
+
+import json
+import platform
+from unittest.mock import patch, MagicMock
+
+import pytest
+
+from agent.anthropic_adapter import (
+    _read_claude_code_credentials_from_keychain,
+    read_claude_code_credentials,
+)
+
+
+class TestReadClaudeCodeCredentialsFromKeychain:
+    """Bug 4: macOS Keychain support for Claude Code >=2.1.114."""
+
+    def test_returns_none_on_linux(self):
+        """Keychain reading is Darwin-only; must return None on other platforms."""
+        with patch("agent.anthropic_adapter.platform.system", return_value="Linux"):
+            assert _read_claude_code_credentials_from_keychain() is None
+
+    def test_returns_none_on_windows(self):
+        with patch("agent.anthropic_adapter.platform.system", return_value="Windows"):
+            assert _read_claude_code_credentials_from_keychain() is None
+
+    def test_returns_none_when_security_command_not_found(self):
+        """OSError from missing security binary must be handled gracefully."""
+        with patch("agent.anthropic_adapter.platform.system", return_value="Darwin"), \
+             patch("agent.anthropic_adapter.subprocess.run",
+                   side_effect=OSError("security not found")):
+            assert _read_claude_code_credentials_from_keychain() is None
+
+    def test_returns_none_on_nonzero_exit_code(self):
+        """security returns non-zero when the Keychain entry doesn't exist."""
+        with patch("agent.anthropic_adapter.platform.system", return_value="Darwin"), \
+             patch("agent.anthropic_adapter.subprocess.run") as mock_run:
+            mock_run.return_value = MagicMock(returncode=1, stdout="", stderr="")
+            assert _read_claude_code_credentials_from_keychain() is None
+
+    def test_returns_none_for_empty_stdout(self):
+        with patch("agent.anthropic_adapter.platform.system", return_value="Darwin"), \
+             patch("agent.anthropic_adapter.subprocess.run") as mock_run:
+            mock_run.return_value = MagicMock(returncode=0, stdout="", stderr="")
+            assert _read_claude_code_credentials_from_keychain() is None
+
+    def test_returns_none_for_non_json_payload(self):
+        with patch("agent.anthropic_adapter.platform.system", return_value="Darwin"), \
+             patch("agent.anthropic_adapter.subprocess.run") as mock_run:
+            mock_run.return_value = MagicMock(returncode=0, stdout="not valid json", stderr="")
+            assert _read_claude_code_credentials_from_keychain() is None
+
+    def test_returns_none_when_password_field_is_missing_claude_ai_oauth(self):
+        with patch("agent.anthropic_adapter.platform.system", return_value="Darwin"), \
+             patch("agent.anthropic_adapter.subprocess.run") as mock_run:
+            mock_run.return_value = MagicMock(
+                returncode=0,
+                stdout=json.dumps({"someOtherService": {"accessToken": "tok"}}),
+                stderr="",
+            )
+            assert _read_claude_code_credentials_from_keychain() is None
+
+    def test_returns_none_when_access_token_is_empty(self):
+        with patch("agent.anthropic_adapter.platform.system", return_value="Darwin"), \
+             patch("agent.anthropic_adapter.subprocess.run") as mock_run:
+            mock_run.return_value = MagicMock(
+                returncode=0,
+                stdout=json.dumps({"claudeAiOauth": {"accessToken": "", "refreshToken": "x"}}),
+                stderr="",
+            )
+            assert _read_claude_code_credentials_from_keychain() is None
+
+    def test_parses_valid_keychain_entry(self):
+        with patch("agent.anthropic_adapter.platform.system", return_value="Darwin"), \
+             patch("agent.anthropic_adapter.subprocess.run") as mock_run:
+            mock_run.return_value = MagicMock(
+                returncode=0,
+                stdout=json.dumps({
+                    "claudeAiOauth": {
+                        "accessToken": "kc-access-token-abc",
+                        "refreshToken": "kc-refresh-token-xyz",
+                        "expiresAt": 9999999999999,
+                    }
+                }),
+                stderr="",
+            )
+            creds = _read_claude_code_credentials_from_keychain()
+            assert creds is not None
+            assert creds["accessToken"] == "kc-access-token-abc"
+            assert creds["refreshToken"] == "kc-refresh-token-xyz"
+            assert creds["expiresAt"] == 9999999999999
+            assert creds["source"] == "macos_keychain"
+
+
+class TestReadClaudeCodeCredentialsPriority:
+    """Bug 4: Keychain must be checked before the JSON file."""
+
+    def test_keychain_takes_priority_over_json_file(self, tmp_path, monkeypatch):
+        """When both Keychain and JSON file have credentials, Keychain wins."""
+        # Set up JSON file with "older" token
+        json_cred_file = tmp_path / ".claude" / ".credentials.json"
+        json_cred_file.parent.mkdir(parents=True)
+        json_cred_file.write_text(json.dumps({
+            "claudeAiOauth": {
+                "accessToken": "json-token",
+                "refreshToken": "json-refresh",
+                "expiresAt": 9999999999999,
+            }
+        }))
+        monkeypatch.setattr("agent.anthropic_adapter.Path.home", lambda: tmp_path)
+
+        # Mock Keychain to return a "newer" token
+        with patch("agent.anthropic_adapter.platform.system", return_value="Darwin"), \
+             patch("agent.anthropic_adapter.subprocess.run") as mock_run:
+            mock_run.return_value = MagicMock(
+                returncode=0,
+                stdout=json.dumps({
+                    "claudeAiOauth": {
+                        "accessToken": "keychain-token",
+                        "refreshToken": "keychain-refresh",
+                        "expiresAt": 9999999999999,
+                    }
+                }),
+                stderr="",
+            )
+            creds = read_claude_code_credentials()
+
+        # Keychain token should be returned, not JSON file token
+        assert creds is not None
+        assert creds["accessToken"] == "keychain-token"
+        assert creds["source"] == "macos_keychain"
+
+    def test_falls_back_to_json_when_keychain_returns_none(self, tmp_path, monkeypatch):
+        """When Keychain has no entry, JSON file is used as fallback."""
+        json_cred_file = tmp_path / ".claude" / ".credentials.json"
+        json_cred_file.parent.mkdir(parents=True)
+        json_cred_file.write_text(json.dumps({
+            "claudeAiOauth": {
+                "accessToken": "json-fallback-token",
+                "refreshToken": "json-refresh",
+                "expiresAt": 9999999999999,
+            }
+        }))
+        monkeypatch.setattr("agent.anthropic_adapter.Path.home", lambda: tmp_path)
+
+        with patch("agent.anthropic_adapter.platform.system", return_value="Darwin"), \
+             patch("agent.anthropic_adapter.subprocess.run") as mock_run:
+            # Simulate Keychain entry not found
+            mock_run.return_value = MagicMock(returncode=1, stdout="", stderr="")
+            creds = read_claude_code_credentials()
+
+        assert creds is not None
+        assert creds["accessToken"] == "json-fallback-token"
+        assert creds["source"] == "claude_code_credentials_file"
+
+    def test_returns_none_when_neither_keychain_nor_json_has_creds(self, tmp_path, monkeypatch):
+        """No credentials anywhere — must return None cleanly."""
+        monkeypatch.setattr("agent.anthropic_adapter.Path.home", lambda: tmp_path)
+
+        with patch("agent.anthropic_adapter.platform.system", return_value="Darwin"), \
+             patch("agent.anthropic_adapter.subprocess.run") as mock_run:
+            mock_run.return_value = MagicMock(returncode=1, stdout="", stderr="")
+            creds = read_claude_code_credentials()
+
+        assert creds is None
diff --git a/tests/hermes_cli/test_anthropic_model_flow_stale_oauth.py b/tests/hermes_cli/test_anthropic_model_flow_stale_oauth.py
new file mode 100644
index 000000000..85055e108
--- /dev/null
+++ b/tests/hermes_cli/test_anthropic_model_flow_stale_oauth.py
@@ -0,0 +1,210 @@
+"""Tests for Bug #12905 fix — stale OAuth token detection in hermes model flow.
+
+Bug 3: `hermes model` with `provider=anthropic` skips OAuth re-authentication
+when a stale ANTHROPIC_TOKEN exists in ~/.hermes/.env but no valid
+Claude Code credentials are available. The fast-path silently proceeds to
+model selection with a broken token instead of offering re-auth.
+"""
+
+import json
+import pytest
+from unittest.mock import patch, MagicMock
+
+from hermes_cli.config import load_env, save_env_value
+
+
+class TestStaleOAuthTokenDetection:
+    """Bug 3: stale OAuth token must trigger needs_auth=True in _model_flow_anthropic."""
+
+    def test_stale_oauth_token_triggers_reauth(self, tmp_path, monkeypatch, capsys):
+        """
+        Scenario: ANTHROPIC_TOKEN is an expired OAuth token and there are no
+        valid Claude Code credentials anywhere. The flow MUST offer re-auth
+        instead of silently skipping to model selection.
+        """
+        monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+
+        # Pre-load .env with an expired OAuth token (sk-ant- prefix = OAuth)
+        save_env_value("ANTHROPIC_TOKEN", "sk-ant-oat-ExpiredToken00000")
+        save_env_value("ANTHROPIC_API_KEY", "")
+
+        # No valid Claude Code credentials available (expired, no refresh token)
+        monkeypatch.setattr(
+            "agent.anthropic_adapter.read_claude_code_credentials",
+            lambda: {
+                "accessToken": "expired-cc-token",
+                "refreshToken": "",          # No refresh — can't recover
+                "expiresAt": 0,               # Already expired
+                "source": "claude_code_credentials_file",
+            },
+        )
+        monkeypatch.setattr(
+            "agent.anthropic_adapter.is_claude_code_token_valid",
+            lambda creds: False,             # Explicitly expired
+        )
+        monkeypatch.setattr(
+            "agent.anthropic_adapter._is_oauth_token",
+            lambda key: key.startswith("sk-ant-"),
+        )
+        # _resolve_claude_code_token_from_credentials has no valid path
+        monkeypatch.setattr(
+            "agent.anthropic_adapter._resolve_claude_code_token_from_credentials",
+            lambda creds=None: None,
+        )
+
+        # Simulate user types "3" (Cancel) when prompted for re-auth
+        monkeypatch.setattr("builtins.input", lambda _: "3")
+        monkeypatch.setattr("getpass.getpass", lambda _: "")
+
+        from hermes_cli.main import _model_flow_anthropic
+        cfg = {}
+
+        _model_flow_anthropic(cfg)
+
+        output = capsys.readouterr().out
+        # Must show auth method choice since token is stale
+        assert "subscription" in output or "API key" in output, (
+            f"Expected auth method menu but got: {output!r}"
+        )
+
+    def test_valid_api_key_skips_stale_check(self, tmp_path, monkeypatch, capsys):
+        """
+        A non-OAuth ANTHROPIC_API_KEY (regular pay-per-token key) must NOT be
+        flagged as stale even when cc_creds are invalid. Regular API keys don't
+        expire the same way OAuth tokens do.
+        """
+        monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+
+        # Regular API key — NOT an OAuth token
+        save_env_value("ANTHROPIC_API_KEY", "sk-ant-api03-RegularPayPerTokenKey")
+        save_env_value("ANTHROPIC_TOKEN", "")
+
+        monkeypatch.setattr(
+            "agent.anthropic_adapter.read_claude_code_credentials",
+            lambda: None,   # No CC creds
+        )
+        monkeypatch.setattr(
+            "agent.anthropic_adapter.is_claude_code_token_valid",
+            lambda creds: False,
+        )
+        monkeypatch.setattr(
+            "agent.anthropic_adapter._is_oauth_token",
+            lambda key: key.startswith("sk-ant-") and "oat" in key,
+        )
+
+        # Simulate user picks "1" (use existing)
+        monkeypatch.setattr("builtins.input", lambda _: "1")
+
+        from hermes_cli.main import _model_flow_anthropic
+        cfg = {}
+
+        _model_flow_anthropic(cfg)
+
+        output = capsys.readouterr().out
+        # Should show "Use existing credentials" menu, NOT auth method choice
+        assert "Use existing" in output or "credentials" in output.lower()
+
+    def test_valid_oauth_token_with_refresh_available_skips_reauth(self, tmp_path, monkeypatch, capsys):
+        """
+        When ANTHROPIC_TOKEN is OAuth and valid cc_creds with refresh exist,
+        the flow should use existing credentials (no forced re-auth).
+        """
+        monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+
+        save_env_value("ANTHROPIC_TOKEN", "sk-ant-oat-GoodOAuthToken")
+        save_env_value("ANTHROPIC_API_KEY", "")
+
+        # Valid Claude Code credentials with refresh token
+        monkeypatch.setattr(
+            "agent.anthropic_adapter.read_claude_code_credentials",
+            lambda: {
+                "accessToken": "valid-cc-token",
+                "refreshToken": "valid-refresh",
+                "expiresAt": 9999999999999,
+            },
+        )
+        monkeypatch.setattr(
+            "agent.anthropic_adapter.is_claude_code_token_valid",
+            lambda creds: True,
+        )
+        monkeypatch.setattr(
+            "agent.anthropic_adapter._is_oauth_token",
+            lambda key: key.startswith("sk-ant-"),
+        )
+        monkeypatch.setattr(
+            "agent.anthropic_adapter._resolve_claude_code_token_from_credentials",
+            lambda creds=None: "valid-cc-token",
+        )
+
+        # Simulate user picks "1" (use existing)
+        monkeypatch.setattr("builtins.input", lambda _: "1")
+
+        from hermes_cli.main import _model_flow_anthropic
+        cfg = {}
+
+        _model_flow_anthropic(cfg)
+
+        output = capsys.readouterr().out
+        # Should show "Use existing" without forcing re-auth
+        assert "Use existing" in output or "credentials" in output.lower()
+
+
+class TestStaleOAuthGuardLogic:
+    """Unit-level test of the stale-OAuth detection guard logic."""
+
+    def test_stale_oauth_flag_logic_no_cc_creds(self):
+        """
+        When existing_key is OAuth and cc_available is False,
+        existing_is_stale_oauth should be True → has_creds = False.
+        """
+        existing_key = "sk-ant-oat-expiredtoken123"
+        _is_oauth_token = lambda k: k.startswith("sk-ant-")
+        cc_available = False
+
+        existing_is_stale_oauth = (
+            bool(existing_key) and
+            _is_oauth_token(existing_key) and
+            not cc_available
+        )
+        has_creds = (bool(existing_key) and not existing_is_stale_oauth) or cc_available
+
+        assert existing_is_stale_oauth is True
+        assert has_creds is False
+
+    def test_stale_oauth_flag_logic_with_valid_cc_creds(self):
+        """
+        When existing_key is OAuth but cc_available is True (valid creds exist),
+        has_creds should be True — the cc_creds will be used instead.
+        """
+        existing_key = "sk-ant-oat-sometoken"
+        _is_oauth_token = lambda k: k.startswith("sk-ant-")
+        cc_available = True
+
+        existing_is_stale_oauth = (
+            bool(existing_key) and
+            _is_oauth_token(existing_key) and
+            not cc_available
+        )
+        has_creds = (bool(existing_key) and not existing_is_stale_oauth) or cc_available
+
+        assert existing_is_stale_oauth is False
+        assert has_creds is True
+
+    def test_non_oauth_key_not_flagged_as_stale(self):
+        """
+        Regular ANTHROPIC_API_KEY (non-OAuth) must not be flagged as stale
+        even when cc_available is False.
+        """
+        existing_key = "sk-ant-api03-regular-key"
+        _is_oauth_token = lambda k: k.startswith("sk-ant-") and "oat" in k
+        cc_available = False
+
+        existing_is_stale_oauth = (
+            bool(existing_key) and
+            _is_oauth_token(existing_key) and
+            not cc_available
+        )
+        has_creds = (bool(existing_key) and not existing_is_stale_oauth) or cc_available
+
+        assert existing_is_stale_oauth is False
+        assert has_creds is True