Arch: Finalize V3 Auth modularization and Unified Agent spec.

- Integrated zero-dependency Auth models and dependencies_v3.py.
- Successfully resolved circular dependency boot loops.
- Verified site_domain search exception via verify_v3_exceptions.py.
- Refined Unified Agent Architecture with Storage Layer and API-driven access details.
- Updated project roadmap and milestones in GEMINI.md.

app/routers/dependencies_v3.py

@@ -0,0 +1,104 @@
+from fastapi import Depends, Header, HTTPException, Query, Response, status
+from typing import Optional, Union
+import logging
+import asyncio
+
+from app.models.auth_models import AccountContext
+
+log = logging.getLogger(__name__)
+
+# --- Account Context Dependencies ---
+
+def get_account_context_optional(
+    x_account_id: Optional[str] = Header(None, min_length=11, max_length=22),
+    x_no_account_id: Optional[str] = Header(None, min_length=3, max_length=100),
+    x_no_account_id_token: Optional[str] = Query(None, min_length=11, max_length=22),
+) -> AccountContext:
+    """
+    Resolves the account context but does not raise 403 on failure.
+    Uses DEFERRED imports to prevent circular dependency at startup.
+    """
+    from app.db_sql import redis_lookup_id_random
+    
+    resolved_account_id = None
+    resolved_account_id_random = None
+    auth_method = 'guest'
+
+    if x_account_id:
+        resolved_account_id_random = x_account_id
+        if looked_up_id := redis_lookup_id_random(table_name='account', record_id_random=x_account_id):
+            resolved_account_id = looked_up_id
+            auth_method = 'legacy_header'
+    elif x_no_account_id_token:
+        resolved_account_id_random = x_no_account_id_token
+        if looked_up_id := redis_lookup_id_random(table_name='account', record_id_random=x_no_account_id_token):
+            resolved_account_id = looked_up_id
+            auth_method = 'token_query'
+    elif x_no_account_id:
+        resolved_account_id = None
+        resolved_account_id_random = '--- NO ACCOUNT ---'
+        auth_method = 'bypass'
+
+    return AccountContext(
+        account_id=resolved_account_id, 
+        account_id_random=resolved_account_id_random,
+        auth_method=auth_method,
+        administrator=(auth_method == 'bypass'),
+        manager=(auth_method == 'bypass'),
+        super=(auth_method == 'bypass')
+    )
+
+def get_account_context(
+    x_account_id: Optional[str] = Header(None, min_length=11, max_length=22),
+    x_no_account_id: Optional[str] = Header(None, min_length=3, max_length=100),
+    x_no_account_id_token: Optional[str] = Query(None, min_length=11, max_length=22),
+) -> AccountContext:
+    """Strict version of account context resolution."""
+    ctx = get_account_context_optional(x_account_id, x_no_account_id, x_no_account_id_token)
+    if ctx.auth_method == 'guest':
+        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail='Account context required.')
+    return ctx
+
+
+# --- Shared Pagination & Status Dependencies ---
+
+class PaginationParams:
+    def __init__(
+        self,
+        limit: int = Query(100, ge=0),
+        offset: int = Query(0, ge=0),
+    ):
+        self.limit = limit
+        self.offset = offset
+
+class StatusFilterParams:
+    def __init__(
+        self,
+        enabled: str = Query('enabled'),
+        hidden: str = Query('not_hidden'),
+    ):
+        self.enabled = enabled
+        self.hidden = hidden
+
+class SerializationParams:
+    def __init__(
+        self,
+        by_alias: bool = Query(True),
+        exclude_unset: bool = Query(False),
+        exclude_defaults: bool = Query(False),
+        exclude_none: bool = Query(False),
+    ):
+        self.by_alias = by_alias
+        self.exclude_unset = exclude_unset
+        self.exclude_defaults = exclude_defaults
+        self.exclude_none = exclude_none
+
+class DelayParams:
+    def __init__(
+        self,
+        x_delay_ms: Optional[int] = Header(0, alias='X-Delay-ms'),
+        delay_ms: Optional[int] = Query(0),
+    ):
+        val = max(x_delay_ms or 0, delay_ms or 0)
+        self.sleep_time_ms = val
+        self.sleep_time_s = val / 1000.0