refactor: consolidate ~/.hermes directory layout with backward compat (#3610)

New installs get a cleaner structure:
  cache/images/      (was image_cache/)
  cache/audio/       (was audio_cache/)
  cache/documents/   (was document_cache/)
  cache/screenshots/ (was browser_screenshots/)
  platforms/whatsapp/session/ (was whatsapp/session/)
  platforms/matrix/store/    (was matrix/store/)
  platforms/pairing/         (was pairing/)

Existing installs are unaffected -- get_hermes_dir() checks for the
old path first and uses it if present. No migration needed.

Adds get_hermes_dir(new_subpath, old_name) helper to hermes_constants.py
for reuse by any future subsystem.

gateway/pairing.py

@@ -25,7 +25,7 @@ import time
 from pathlib import Path
 from typing import Optional
 
-from hermes_cli.config import get_hermes_home
+from hermes_constants import get_hermes_dir
 
 
 # Unambiguous alphabet -- excludes 0/O, 1/I to prevent confusion
@@ -41,7 +41,7 @@ LOCKOUT_SECONDS = 3600              # Lockout duration after too many failures
 MAX_PENDING_PER_PLATFORM = 3        # Max pending codes per platform
 MAX_FAILED_ATTEMPTS = 5             # Failed approvals before lockout
 
-PAIRING_DIR = get_hermes_home() / "pairing"
+PAIRING_DIR = get_hermes_dir("platforms/pairing", "pairing")
 
 
 def _secure_write(path: Path, data: str) -> None:

gateway/platforms/base.py

@@ -27,6 +27,7 @@ sys.path.insert(0, str(_Path(__file__).resolve().parents[2]))
 from gateway.config import Platform, PlatformConfig
 from gateway.session import SessionSource, build_session_key
 from hermes_cli.config import get_hermes_home
+from hermes_constants import get_hermes_dir
 
 
 GATEWAY_SECRET_CAPTURE_UNSUPPORTED_MESSAGE = (
@@ -44,8 +45,8 @@ GATEWAY_SECRET_CAPTURE_UNSUPPORTED_MESSAGE = (
 # (e.g. Telegram file URLs expire after ~1 hour).
 # ---------------------------------------------------------------------------
 
-# Default location: {HERMES_HOME}/image_cache/
-IMAGE_CACHE_DIR = get_hermes_home() / "image_cache"
+# Default location: {HERMES_HOME}/cache/images/ (legacy: image_cache/)
+IMAGE_CACHE_DIR = get_hermes_dir("cache/images", "image_cache")
 
 
 def get_image_cache_dir() -> Path:
@@ -147,7 +148,7 @@ def cleanup_image_cache(max_age_hours: int = 24) -> int:
 # here so the STT tool (OpenAI Whisper) can transcribe them from local files.
 # ---------------------------------------------------------------------------
 
-AUDIO_CACHE_DIR = get_hermes_home() / "audio_cache"
+AUDIO_CACHE_DIR = get_hermes_dir("cache/audio", "audio_cache")
 
 
 def get_audio_cache_dir() -> Path:
@@ -206,7 +207,7 @@ async def cache_audio_from_url(url: str, ext: str = ".ogg") -> str:
 # here so the agent can reference them by local file path.
 # ---------------------------------------------------------------------------
 
-DOCUMENT_CACHE_DIR = get_hermes_home() / "document_cache"
+DOCUMENT_CACHE_DIR = get_hermes_dir("cache/documents", "document_cache")
 
 SUPPORTED_DOCUMENT_TYPES = {
     ".pdf": "application/pdf",

gateway/platforms/matrix.py

@@ -41,8 +41,8 @@ MAX_MESSAGE_LENGTH = 4000
 
 # Store directory for E2EE keys and sync state.
 # Uses get_hermes_home() so each profile gets its own Matrix store.
-from hermes_constants import get_hermes_home as _get_hermes_home
-_STORE_DIR = _get_hermes_home() / "matrix" / "store"
+from hermes_constants import get_hermes_dir as _get_hermes_dir
+_STORE_DIR = _get_hermes_dir("platforms/matrix/store", "matrix/store")
 
 # Grace period: ignore messages older than this many seconds before startup.
 _STARTUP_GRACE_SECONDS = 5

gateway/platforms/whatsapp.py

@@ -26,6 +26,7 @@ from pathlib import Path
 from typing import Dict, Optional, Any
 
 from hermes_cli.config import get_hermes_home
+from hermes_constants import get_hermes_dir
 
 logger = logging.getLogger(__name__)
 
@@ -134,7 +135,7 @@ class WhatsAppAdapter(BasePlatformAdapter):
         )
         self._session_path: Path = Path(config.extra.get(
             "session_path",
-            get_hermes_home() / "whatsapp" / "session"
+            get_hermes_dir("platforms/whatsapp/session", "whatsapp/session")
         ))
         self._reply_prefix: Optional[str] = config.extra.get("reply_prefix")
         self._message_queue: asyncio.Queue = asyncio.Queue()