feat(codex): inject host credentials via egress

bot_bottle/codex_auth.py

@@ -0,0 +1,96 @@
+"""Host Codex auth helpers.
+
+Reads the host's Codex ChatGPT/device-login auth state and returns only
+the short-lived access token needed by egress. This module deliberately
+does not expose refresh tokens or raw auth payloads.
+"""
+
+from __future__ import annotations
+
+import base64
+import json
+import os
+from datetime import datetime, timezone
+from pathlib import Path
+
+from .log import die
+from .util import expand_tilde
+
+
+def codex_auth_path(host_env: dict[str, str] | None = None) -> Path:
+    env = os.environ if host_env is None else host_env
+    home = env.get("CODEX_HOME")
+    if home:
+        return Path(expand_tilde(home)) / "auth.json"
+    return Path.home() / ".codex" / "auth.json"
+
+
+def codex_host_access_token(
+    host_env: dict[str, str] | None = None,
+    *,
+    now: datetime | None = None,
+) -> str:
+    path = codex_auth_path(host_env)
+    if not path.is_file():
+        die(
+            f"codex host credentials: auth file missing at {path}. "
+            "Run `codex login --device-auth` on the host or disable "
+            "agent_provider.forward_host_credentials."
+        )
+    try:
+        raw = json.loads(path.read_text())
+    except (OSError, json.JSONDecodeError) as e:
+        die(f"codex host credentials: could not read valid JSON at {path}: {e}")
+    if not isinstance(raw, dict):
+        die(f"codex host credentials: {path} must contain a JSON object")
+
+    if raw.get("auth_mode") != "chatgpt":
+        die(
+            "codex host credentials: host Codex auth is not ChatGPT/device "
+            "auth. Run `codex login --device-auth` on the host."
+        )
+
+    tokens = raw.get("tokens")
+    if not isinstance(tokens, dict):
+        die(f"codex host credentials: {path} is missing tokens")
+    access = tokens.get("access_token")
+    if not isinstance(access, str) or not access:
+        die(
+            f"codex host credentials: {path} is missing tokens.access_token. "
+            "Run `codex login --device-auth` on the host."
+        )
+
+    exp = _jwt_exp(access)
+    if exp is None:
+        die("codex host credentials: tokens.access_token is not a JWT with exp")
+    check_now = now or datetime.now(timezone.utc)
+    if exp <= check_now:
+        die(
+            "codex host credentials: host Codex access token is expired. "
+            "Run `codex login --device-auth` on the host and restart the bottle."
+        )
+    return access
+
+
+def _jwt_exp(token: str) -> datetime | None:
+    parts = token.split(".")
+    if len(parts) < 2:
+        return None
+    try:
+        payload = json.loads(_b64url_decode(parts[1]))
+    except (ValueError, json.JSONDecodeError):
+        return None
+    if not isinstance(payload, dict):
+        return None
+    exp = payload.get("exp")
+    if not isinstance(exp, (int, float)):
+        return None
+    return datetime.fromtimestamp(exp, timezone.utc)
+
+
+def _b64url_decode(value: str) -> str:
+    padded = value + ("=" * (-len(value) % 4))
+    return base64.urlsafe_b64decode(padded.encode("ascii")).decode("utf-8")
+
+
+__all__ = ["codex_auth_path", "codex_host_access_token"]