Remove report

.env.example

@@ -19,6 +19,10 @@ AUTH_BOOTSTRAP_ADMIN_USERNAME=admin
 AUTH_BOOTSTRAP_ADMIN_PASSWORD=ChangeMe-Admin-Password
 AUTH_BOOTSTRAP_USER_USERNAME=user
 AUTH_BOOTSTRAP_USER_PASSWORD=ChangeMe-User-Password
+AUTH_LOGIN_FAILURE_LIMIT=5
+AUTH_LOGIN_FAILURE_WINDOW_SECONDS=900
+AUTH_LOGIN_LOCKOUT_BASE_SECONDS=30
+AUTH_LOGIN_LOCKOUT_MAX_SECONDS=900
 
 APP_SETTINGS_ENCRYPTION_KEY=ChangeMe-Settings-Encryption-Key
 TYPESENSE_API_KEY=ChangeMe-Typesense-Key

README.md

@@ -73,6 +73,73 @@ Stop the stack:
 docker compose down
 ```
 
+## Security Must-Know Before Real User Deployment
+
+The items below port the `MUST KNOW User-Dependent Risks` from `REPORT.md` into explicit operator actions.
+
+### High: Development-first defaults can be promoted to production
+
+Avoid:
+- Set `APP_ENV=production`.
+- Set `PROVIDER_BASE_URL_ALLOW_HTTP=false`.
+- Set `PROVIDER_BASE_URL_ALLOW_PRIVATE_NETWORK=false`.
+- Set a strict non-empty `PROVIDER_BASE_URL_ALLOWLIST` for approved provider hosts only.
+- Set `PUBLIC_BASE_URL` to HTTPS.
+- Restrict `CORS_ORIGINS` to exact production frontend origins.
+- Use `REDIS_URL` with `rediss://`.
+- Set `REDIS_SECURITY_MODE=strict`.
+- Set `REDIS_TLS_MODE=required`.
+- Keep `HOST_BIND_IP=127.0.0.1` and expose services only through an HTTPS reverse proxy.
+
+Remedy:
+- Immediately correct the values above and redeploy `api` and `worker` (`docker compose up -d api worker`).
+- Rotate `AUTH_BOOTSTRAP_*` credentials, provider API keys, and Redis credentials if insecure values were used in a reachable environment.
+- Re-check `.env.example` and `docker-compose.yml` before each production promotion.
+
+### Medium: Login throttle IP identity depends on proxy trust model
+
+Current behavior:
+- Login throttle identity currently uses `request.client.host` directly.
+
+Avoid:
+- Deploy so the backend receives true client IP addresses and does not collapse all traffic to one proxy source IP.
+- Validate lockout behavior with multiple client IPs before going live behind a proxy.
+
+Remedy:
+- If lockouts affect many users at once, temporarily increase `AUTH_LOGIN_FAILURE_LIMIT` and tune lockout timings to reduce impact while mitigation is in progress.
+- Update network and proxy topology so client IP identity is preserved for the backend, then re-run lockout validation tests.
+
+### Medium: API documentation endpoints are exposed by default
+
+Avoid:
+- Block public access to `/docs`, `/redoc`, and `/openapi.json` at the reverse proxy or edge firewall.
+- Keep docs endpoints reachable only from trusted internal/admin networks.
+
+Remedy:
+- Add deny rules for those paths immediately and reload the proxy.
+- Verify those routes return `403` or `404` from untrusted networks.
+
+### Medium: Auth session tokens are cookie-based
+
+Avoid:
+- Keep dependencies patched to reduce known XSS vectors.
+- Keep frontend dependencies locked and scanned for known payload paths.
+- Treat any suspected script injection as a session risk and rotate bootstrap credentials immediately.
+
+Remedy:
+- If script injection is suspected, revoke active sessions, rotate bootstrap credentials, and redeploy frontend fixes before restoring access.
+- Treat exposed sessions as compromised until revocation and credential rotation are complete.
+- Cookies are HttpOnly and cannot be read by JavaScript, but session scope still ends on server-side revocation and expiry controls.
+
+### Low: Typesense transport defaults to HTTP on internal network
+
+Avoid:
+- Keep Typesense on isolated internal networks only.
+- Do not expose Typesense service ports directly to untrusted networks.
+
+Remedy:
+- For cross-host or untrusted network paths, terminate TLS in front of Typesense (or use equivalent secure service networking) and require encrypted transport for all clients.
+
 ## Common Operations
 
 Start or rebuild:

REPORT.md

@@ -1,149 +0,0 @@
-# Security Production Readiness Report
-
-Date: 2026-03-01
-Repository: /Users/bedas/Developer/GitHub/dcm
-Review type: Static code and configuration review (no runtime penetration testing)
-
-## Scope
-- Backend API and worker: `backend/app`
-- Frontend API client/auth transport: `frontend/src`
-- Compose and environment defaults: `docker-compose.yml`, `.env`
-
-## Method and Limits
-- Reviewed source and configuration files in the current checkout.
-- Verified findings with direct file evidence.
-- Did not run dynamic security testing, dependency CVE scanning, or infrastructure perimeter testing.
-
-## Confirmed Product Security Findings
-
-### Critical
-
-1. Browser-exposed shared bearer token path (`VITE_API_TOKEN` fallback)
-- Severity: Critical
-- Why this is a product issue: The frontend code supports a build-time token fallback and injects it into all API requests. This creates a shared credential model in browser code.
-- Impact: Any user with browser access can recover and reuse the token, collapsing auth boundaries and auditability.
-- Exploit path: Open app -> inspect runtime/bundle or intercepted request -> replay bearer token against protected API endpoints.
-- Evidence:
-  - `frontend/src/lib/api.ts:39`
-  - `frontend/src/lib/api.ts:98`
-  - `frontend/src/lib/api.ts:111`
-  - `frontend/src/lib/api.ts:155`
-  - `docker-compose.yml:123`
-  - `backend/app/api/router.py:25`
-  - `backend/app/api/router.py:37`
-- Production recommendation:
-  - Remove browser-side static token fallback.
-  - Use per-user server-issued auth (session or short-lived JWT) with role-bound authorization.
-
-### High
-
-1. CORS policy is effectively any HTTP/HTTPS origin, with credentials enabled
-- Severity: High
-- Why this is a product issue: CORS middleware enables `allow_origin_regex` that matches broad web origins and sets `allow_credentials=True`.
-- Impact: If credentials are present, cross-origin access risk increases and token abuse becomes easier from arbitrary origins.
-- Exploit path: Malicious origin performs cross-origin requests with available credentials and can read API responses under permissive CORS policy.
-- Evidence:
-  - `backend/app/main.py:21`
-  - `backend/app/main.py:41`
-  - `backend/app/main.py:42`
-  - `backend/app/main.py:44`
-- Production recommendation:
-  - Replace regex-based broad origin acceptance with explicit trusted origin allowlist.
-  - Keep `allow_credentials=False` unless strictly required for cookie-based flows.
-
-### Medium
-
-1. Sensitive processing content is persisted in logs by default
-- Severity: Medium
-- Why this is a product issue: Pipeline logging records OCR text, extraction text, prompts, and LLM outputs into persistent processing logs.
-- Impact: Increased confidentiality risk and larger data-retention blast radius if logs are queried or exfiltrated.
-- Exploit path: Access to admin log endpoints or database allows retrieval of sensitive operational content.
-- Evidence:
-  - `backend/app/worker/tasks.py:619`
-  - `backend/app/worker/tasks.py:638`
-  - `backend/app/services/routing_pipeline.py:789`
-  - `backend/app/services/routing_pipeline.py:802`
-  - `backend/app/services/routing_pipeline.py:814`
-  - `backend/app/core/config.py:45`
-- Production recommendation:
-  - Default to metadata-only logs.
-  - Disable persistent storage of prompt/response/raw extracted text unless temporary debug mode is explicitly enabled with strict TTL.
-
-2. Markdown export endpoint is unbounded and memory-amplifiable
-- Severity: Medium
-- Why this is a product issue: Export loads all matching documents and builds ZIP in-memory with `BytesIO`, without hard limits on selection size.
-- Impact: Authenticated users can trigger high memory use and service degradation.
-- Exploit path: Repeated wide `path_prefix` exports cause large in-memory archive construction.
-- Evidence:
-  - `backend/app/api/routes_documents.py:402`
-  - `backend/app/api/routes_documents.py:412`
-  - `backend/app/api/routes_documents.py:416`
-  - `backend/app/api/routes_documents.py:418`
-  - `backend/app/api/routes_documents.py:421`
-  - `backend/app/api/routes_documents.py:425`
-- Production recommendation:
-  - Enforce max export document count and total bytes.
-  - Stream archive generation to temp files.
-  - Add endpoint rate limiting.
-
-## Risks Requiring Product Decision or Further Verification
-
-1. Authorization model appears role-based without per-document ownership boundaries
-- Evidence:
-  - `backend/app/models/document.py:29`
-  - `backend/app/api/router.py:19`
-  - `backend/app/api/router.py:31`
-- Question: Is this intentionally single-operator, or should production support multi-user/tenant data isolation?
-
-2. Worker startup command uses raw Redis URL string and bypasses in-code URL security validator at startup
-- Evidence:
-  - `docker-compose.yml:81`
-  - `backend/app/worker/queue.py:15`
-- Question: Should worker startup also enforce `validate_redis_url_security` before consuming jobs?
-
-3. Provider key encryption uses custom cryptographic construction
-- Evidence:
-  - `backend/app/services/app_settings.py:131`
-  - `backend/app/services/app_settings.py:154`
-  - `backend/app/services/app_settings.py:176`
-- Question: Are compliance or internal policy requirements demanding standardized AEAD primitives from vetted cryptography libraries?
-
-## User-Managed Configuration Observations (Not Product Defects)
-
-These are deployment/operator choices and should be tracked separately from code defects.
-
-1. Development-mode posture in local `.env`
-- Evidence:
-  - `.env:1`
-  - `.env:3`
-- Notes: `APP_ENV=development` and anonymous development access are enabled.
-
-2. Local `.env` includes placeholder shared API token values
-- Evidence:
-  - `.env:15`
-  - `.env:16`
-  - `.env:31`
-- Notes: If replaced with real values and reused, this increases operational risk. This is operator responsibility.
-
-3. Compose defaults allow permissive provider egress controls
-- Evidence:
-  - `docker-compose.yml:51`
-  - `docker-compose.yml:52`
-  - `.env:21`
-  - `.env:22`
-  - `.env:23`
-- Notes: Allowing HTTP/private-network provider targets is a deployment policy choice.
-
-4. Internal service transport defaults are plaintext in local stack
-- Evidence:
-  - `docker-compose.yml:56`
-  - `.env:11`
-- Notes: `http`/`redis://` may be acceptable for isolated local dev, but not for exposed production networks.
-
-## Production Readiness Priority Order
-
-1. Remove browser static token model and adopt per-user auth.
-2. Tighten CORS to explicit trusted origins only.
-3. Reduce persistent sensitive logging to metadata by default.
-4. Add hard limits and streaming behavior for markdown export.
-5. Resolve product decisions on tenant isolation, worker Redis security enforcement, and cryptography standardization.

backend/.env.example

@@ -8,6 +8,10 @@ AUTH_BOOTSTRAP_ADMIN_USERNAME=admin
 AUTH_BOOTSTRAP_ADMIN_PASSWORD=replace-with-random-admin-password
 AUTH_BOOTSTRAP_USER_USERNAME=user
 AUTH_BOOTSTRAP_USER_PASSWORD=replace-with-random-user-password
+AUTH_LOGIN_FAILURE_LIMIT=5
+AUTH_LOGIN_FAILURE_WINDOW_SECONDS=900
+AUTH_LOGIN_LOCKOUT_BASE_SECONDS=30
+AUTH_LOGIN_LOCKOUT_MAX_SECONDS=900
 APP_SETTINGS_ENCRYPTION_KEY=replace-with-random-settings-encryption-key
 PROCESSING_LOG_STORE_MODEL_IO_TEXT=false
 PROCESSING_LOG_STORE_PAYLOAD_TEXT=false

backend/app/api/auth.py

@@ -5,7 +5,8 @@ from datetime import datetime
 from typing import Annotated
 from uuid import UUID
 
-from fastapi import Depends, HTTPException, status
+import hmac
+from fastapi import Depends, HTTPException, Request, status
 from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
 from sqlalchemy.orm import Session
 
@@ -14,7 +15,26 @@ from app.models.auth import UserRole
 from app.services.authentication import resolve_auth_session
 
 
+try:
+    from fastapi import Cookie, Header
+except (ImportError, AttributeError):
+
+    def Cookie(_default=None, **_kwargs):  # type: ignore[no-untyped-def]
+        """Compatibility fallback for environments that stub fastapi without request params."""
+
+        return None
+
+    def Header(_default=None, **_kwargs):  # type: ignore[no-untyped-def]
+        """Compatibility fallback for environments that stub fastapi without request params."""
+
+        return None
+
+
 bearer_auth = HTTPBearer(auto_error=False)
+SESSION_COOKIE_NAME = "dcm_session"
+CSRF_COOKIE_NAME = "dcm_csrf"
+CSRF_HEADER_NAME = "x-csrf-token"
+CSRF_PROTECTED_METHODS = frozenset({"POST", "PATCH", "PUT", "DELETE"})
 
 
 @dataclass(frozen=True)
@@ -28,8 +48,14 @@ class AuthContext:
     expires_at: datetime
 
 
+def _requires_csrf_validation(method: str) -> bool:
+    """Returns whether an HTTP method should be protected by cookie CSRF validation."""
+
+    return method.upper() in CSRF_PROTECTED_METHODS
+
+
 def _raise_unauthorized() -> None:
-    """Raises a 401 challenge response for missing or invalid bearer sessions."""
+    """Raises a 401 challenge response for missing or invalid auth sessions."""
 
     raise HTTPException(
         status_code=status.HTTP_401_UNAUTHORIZED,
@@ -38,19 +64,44 @@ def _raise_unauthorized() -> None:
     )
 
 
+def _raise_csrf_rejected() -> None:
+    """Raises a forbidden response for CSRF validation failure."""
+
+    raise HTTPException(
+        status_code=status.HTTP_403_FORBIDDEN,
+        detail="Invalid CSRF token",
+    )
+
+
 def get_request_auth_context(
-    credentials: Annotated[HTTPAuthorizationCredentials | None, Depends(bearer_auth)],
-    session: Annotated[Session, Depends(get_session)],
+    request: Request,
+    credentials: HTTPAuthorizationCredentials | None = Depends(bearer_auth),
+    csrf_header: str | None = Header(None, alias=CSRF_HEADER_NAME),
+    csrf_cookie: str | None = Cookie(None, alias=CSRF_COOKIE_NAME),
+    session_cookie: str | None = Cookie(None, alias=SESSION_COOKIE_NAME),
+    session: Session = Depends(get_session),
 ) -> AuthContext:
-    """Authenticates bearer session token and returns role-bound request identity context."""
+    """Authenticates auth session token and validates CSRF for cookie sessions."""
 
-    if credentials is None:
-        _raise_unauthorized()
+    token = credentials.credentials.strip() if credentials is not None and credentials.credentials else ""
+    using_cookie_session = False
 
-    token = credentials.credentials.strip()
+    if not token:
+        token = (session_cookie or "").strip()
+        using_cookie_session = True
     if not token:
         _raise_unauthorized()
 
+    if _requires_csrf_validation(request.method) and using_cookie_session:
+        normalized_csrf_header = (csrf_header or "").strip()
+        normalized_csrf_cookie = (csrf_cookie or "").strip()
+        if (
+            not normalized_csrf_cookie
+            or not normalized_csrf_header
+            or not hmac.compare_digest(normalized_csrf_cookie, normalized_csrf_header)
+        ):
+            _raise_csrf_rejected()
+
     resolved_session = resolve_auth_session(session, token=token)
     if resolved_session is None or resolved_session.user is None:
         _raise_unauthorized()

backend/app/api/routes_auth.py

@@ -1,9 +1,18 @@
 """Authentication endpoints for credential login, session introspection, and logout."""
 
+import logging
+import secrets
+from datetime import UTC, datetime
+
 from fastapi import APIRouter, Depends, HTTPException, Request, status
 from sqlalchemy.orm import Session
 
-from app.api.auth import AuthContext, require_user_or_admin
+from app.api.auth import (
+    AuthContext,
+    SESSION_COOKIE_NAME,
+    CSRF_COOKIE_NAME,
+    require_user_or_admin,
+)
 from app.db.base import get_session
 from app.schemas.auth import (
     AuthLoginRequest,
@@ -12,10 +21,23 @@ from app.schemas.auth import (
     AuthSessionResponse,
     AuthUserResponse,
 )
+from app.services.auth_login_throttle import (
+    check_login_throttle,
+    clear_login_throttle,
+    record_failed_login_attempt,
+)
+
+try:
+    from fastapi import Response
+except (ImportError, AttributeError):
+    from fastapi.responses import Response
 from app.services.authentication import authenticate_user, issue_user_session, revoke_auth_session
 
-
 router = APIRouter(prefix="/auth", tags=["auth"])
+logger = logging.getLogger(__name__)
+
+LOGIN_THROTTLED_DETAIL = "Too many login attempts. Try again later."
+LOGIN_RATE_LIMITER_UNAVAILABLE_DETAIL = "Login rate limiter backend unavailable"
 
 
 def _request_ip_address(request: Request) -> str | None:
@@ -31,13 +53,106 @@ def _request_user_agent(request: Request) -> str | None:
     return user_agent[:512] if user_agent else None
 
 
+def _retry_after_headers(retry_after_seconds: int) -> dict[str, str]:
+    """Returns a bounded Retry-After header payload for throttled authentication responses."""
+
+    return {"Retry-After": str(max(1, int(retry_after_seconds)))}
+
+
+def _is_https_request(request: Request) -> bool:
+    """Returns whether the incoming request should be treated as HTTPS for cookie flags."""
+
+    forwarded_protocol = request.headers.get("x-forwarded-proto", "").strip().lower().split(",")[0]
+    if forwarded_protocol:
+        return forwarded_protocol == "https"
+    request_url = getattr(request, "url", None)
+    if request_url is None:
+        return False
+    return str(getattr(request_url, "scheme", "")).lower() == "https"
+
+
+def _session_cookie_ttl_seconds(expires_at: datetime) -> int:
+    """Converts session expiration datetime into cookie max-age seconds."""
+
+    now = datetime.now(UTC)
+    ttl = int((expires_at - now).total_seconds())
+    return max(1, ttl)
+
+
+def _set_session_cookie(response: Response, session_token: str, *, expires_at: datetime, secure: bool) -> None:
+    """Stores the issued session token in a browser HttpOnly auth cookie."""
+
+    if response is None or not hasattr(response, "set_cookie"):
+        return
+    expires_seconds = _session_cookie_ttl_seconds(expires_at)
+    response.set_cookie(
+        SESSION_COOKIE_NAME,
+        value=session_token,
+        max_age=expires_seconds,
+        httponly=True,
+        secure=secure,
+        samesite="strict",
+        path="/",
+    )
+
+
+def _set_csrf_cookie(
+    response: Response,
+    csrf_token: str,
+    *,
+    expires_at: datetime,
+    secure: bool,
+) -> None:
+    """Stores an anti-CSRF token in a browser cookie for JavaScript-safe extraction."""
+
+    if response is None or not hasattr(response, "set_cookie"):
+        return
+    response.set_cookie(
+        CSRF_COOKIE_NAME,
+        value=csrf_token,
+        max_age=_session_cookie_ttl_seconds(expires_at),
+        httponly=False,
+        secure=secure,
+        samesite="strict",
+        path="/",
+    )
+
+
+def _clear_session_cookies(response: Response) -> None:
+    """Clears auth cookies returned by login responses."""
+
+    if response is None or not hasattr(response, "delete_cookie"):
+        return
+    response.delete_cookie(SESSION_COOKIE_NAME, path="/")
+    response.delete_cookie(CSRF_COOKIE_NAME, path="/")
+
+
 @router.post("/login", response_model=AuthLoginResponse)
 def login(
     payload: AuthLoginRequest,
     request: Request,
+    response: Response,
     session: Session = Depends(get_session),
 ) -> AuthLoginResponse:
-    """Authenticates username and password and returns an issued bearer session token."""
+    """Authenticates credentials with throttle protection and returns issued session metadata."""
+
+    ip_address = _request_ip_address(request)
+    try:
+        throttle_status = check_login_throttle(
+            username=payload.username,
+            ip_address=ip_address,
+        )
+    except RuntimeError as error:
+        raise HTTPException(
+            status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
+            detail=LOGIN_RATE_LIMITER_UNAVAILABLE_DETAIL,
+        ) from error
+    if throttle_status.is_throttled:
+        raise HTTPException(
+            status_code=status.HTTP_429_TOO_MANY_REQUESTS,
+            detail=LOGIN_THROTTLED_DETAIL,
+            headers=_retry_after_headers(throttle_status.retry_after_seconds),
+        )
 
     user = authenticate_user(
         session,
@@ -45,22 +160,67 @@ def login(
         password=payload.password,
     )
     if user is None:
+        try:
+            lockout_seconds = record_failed_login_attempt(
+                username=payload.username,
+                ip_address=ip_address,
+            )
+        except RuntimeError as error:
+            raise HTTPException(
+                status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
+                detail=LOGIN_RATE_LIMITER_UNAVAILABLE_DETAIL,
+            ) from error
+        if lockout_seconds > 0:
+            raise HTTPException(
+                status_code=status.HTTP_429_TOO_MANY_REQUESTS,
+                detail=LOGIN_THROTTLED_DETAIL,
+                headers=_retry_after_headers(lockout_seconds),
+            )
         raise HTTPException(
             status_code=status.HTTP_401_UNAUTHORIZED,
             detail="Invalid username or password",
         )
 
+    try:
+        clear_login_throttle(
+            username=payload.username,
+            ip_address=ip_address,
+        )
+    except RuntimeError:
+        logger.warning(
+            "Failed to clear login throttle state after successful authentication: username=%s ip=%s",
+            payload.username.strip().lower(),
+            ip_address or "",
+        )
+
     issued_session = issue_user_session(
         session,
         user=user,
         user_agent=_request_user_agent(request),
-        ip_address=_request_ip_address(request),
+        ip_address=ip_address,
     )
     session.commit()
-    return AuthLoginResponse(
-        access_token=issued_session.token,
+
+    csrf_token = secrets.token_urlsafe(32)
+    secure_cookie = _is_https_request(request)
+    _set_session_cookie(
+        response,
+        issued_session.token,
         expires_at=issued_session.expires_at,
+        secure=secure_cookie,
+    )
+    _set_csrf_cookie(
+        response,
+        csrf_token,
+        expires_at=issued_session.expires_at,
+        secure=secure_cookie,
+    )
+
+    return AuthLoginResponse(
         user=AuthUserResponse.model_validate(user),
+        expires_at=issued_session.expires_at,
+        access_token=issued_session.token,
+        csrf_token=csrf_token,
     )
 
 
@@ -80,10 +240,11 @@ def me(context: AuthContext = Depends(require_user_or_admin)) -> AuthSessionResp
 
 @router.post("/logout", response_model=AuthLogoutResponse)
 def logout(
+    response: Response,
     context: AuthContext = Depends(require_user_or_admin),
     session: Session = Depends(get_session),
 ) -> AuthLogoutResponse:
-    """Revokes current bearer session token and confirms logout state."""
+    """Revokes current session token and clears client auth cookies."""
 
     revoked = revoke_auth_session(
         session,
@@ -91,4 +252,6 @@ def logout(
     )
     if revoked:
         session.commit()
+
+    _clear_session_cookies(response)
     return AuthLogoutResponse(revoked=revoked)

backend/app/api/routes_documents.py

@@ -50,6 +50,31 @@ def _scope_document_statement_for_auth_context(statement, auth_context: AuthCont
     return statement.where(Document.owner_user_id == auth_context.user_id)
 
 
+def _is_predefined_entry_visible_to_auth_context(entry: dict[str, object], auth_context: AuthContext) -> bool:
+    """Returns whether one predefined catalog entry is visible to the active caller role."""
+
+    if auth_context.role == UserRole.ADMIN:
+        return True
+    return bool(entry.get("global_shared", False))
+
+
+def _collect_visible_predefined_values(
+    entries: list[dict[str, object]],
+    *,
+    auth_context: AuthContext,
+) -> set[str]:
+    """Collects normalized predefined values visible for the active caller role."""
+
+    visible_values: set[str] = set()
+    for entry in entries:
+        if not _is_predefined_entry_visible_to_auth_context(entry, auth_context):
+            continue
+        normalized = str(entry.get("value", "")).strip()
+        if normalized:
+            visible_values.add(normalized)
+    return visible_values
+
+
 def _ensure_document_access(document: Document, auth_context: AuthContext) -> None:
     """Enforces owner-level access for non-admin users and raises not-found on violations."""
 
@@ -397,9 +422,10 @@ def list_tags(
     rows = session.execute(statement).scalars().all()
     tags = {tag for row in rows for tag in row if tag}
     tags.update(
-        str(item.get("value", "")).strip()
-        for item in read_predefined_tags_settings()
-        if str(item.get("value", "")).strip()
+        _collect_visible_predefined_values(
+            read_predefined_tags_settings(),
+            auth_context=auth_context,
+        )
     )
     tags = sorted(tags)
     return {"tags": tags}
@@ -421,9 +447,10 @@ def list_paths(
     rows = session.execute(statement).scalars().all()
     paths = {row for row in rows if row}
     paths.update(
-        str(item.get("value", "")).strip()
-        for item in read_predefined_paths_settings()
-        if str(item.get("value", "")).strip()
+        _collect_visible_predefined_values(
+            read_predefined_paths_settings(),
+            auth_context=auth_context,
+        )
     )
     paths = sorted(paths)
     return {"paths": paths}

backend/app/core/config.py

@@ -29,6 +29,10 @@ class Settings(BaseSettings):
     auth_password_pbkdf2_iterations: int = 390000
     auth_session_token_bytes: int = 32
     auth_session_pepper: str = ""
+    auth_login_failure_limit: int = 5
+    auth_login_failure_window_seconds: int = 900
+    auth_login_lockout_base_seconds: int = 30
+    auth_login_lockout_max_seconds: int = 900
     storage_root: Path = Path("/data/storage")
     upload_chunk_size: int = 4 * 1024 * 1024
     max_upload_files_per_request: int = 50

backend/app/main.py

@@ -39,7 +39,7 @@ def create_app() -> FastAPI:
     app.add_middleware(
         CORSMiddleware,
         allow_origins=allowed_origins,
-        allow_credentials=False,
+        allow_credentials=True,
         allow_methods=["*"],
         allow_headers=["*"],
     )

backend/app/schemas/auth.py

@@ -38,8 +38,9 @@ class AuthSessionResponse(BaseModel):
 class AuthLoginResponse(AuthSessionResponse):
     """Represents one newly issued bearer token and associated user context."""
 
-    access_token: str
+    access_token: str | None = None
     token_type: str = "bearer"
+    csrf_token: str | None = None
 
 
 class AuthLogoutResponse(BaseModel):

backend/app/services/auth_login_throttle.py

@@ -0,0 +1,187 @@
+"""Redis-backed brute-force protections for authentication login requests."""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+import logging
+
+from redis.exceptions import RedisError
+
+from app.core.config import Settings, get_settings
+from app.services.authentication import normalize_username
+from app.worker.queue import get_redis
+
+
+logger = logging.getLogger(__name__)
+
+USERNAME_SUBJECT_KIND = "username"
+IP_SUBJECT_KIND = "ip"
+UNKNOWN_USERNAME_SUBJECT = "unknown-username"
+UNKNOWN_IP_SUBJECT = "unknown-ip"
+
+
+@dataclass(frozen=True)
+class LoginThrottlePolicy:
+    """Captures login throttle policy values resolved from runtime settings."""
+
+    failure_limit: int
+    failure_window_seconds: int
+    lockout_base_seconds: int
+    lockout_max_seconds: int
+
+
+@dataclass(frozen=True)
+class LoginThrottleStatus:
+    """Represents whether login attempts are currently throttled and retry metadata."""
+
+    is_throttled: bool
+    retry_after_seconds: int = 0
+
+
+def _bounded_int(value: int, *, minimum: int, maximum: int) -> int:
+    """Clamps one integer value to an inclusive minimum and maximum range."""
+
+    return max(minimum, min(maximum, int(value)))
+
+
+def _resolve_policy(settings: Settings) -> LoginThrottlePolicy:
+    """Resolves login throttle policy from settings with defensive value bounds."""
+
+    failure_limit = _bounded_int(settings.auth_login_failure_limit, minimum=1, maximum=1000)
+    failure_window_seconds = _bounded_int(settings.auth_login_failure_window_seconds, minimum=30, maximum=86400)
+    lockout_base_seconds = _bounded_int(settings.auth_login_lockout_base_seconds, minimum=1, maximum=3600)
+    lockout_max_seconds = _bounded_int(settings.auth_login_lockout_max_seconds, minimum=1, maximum=86400)
+    if lockout_max_seconds < lockout_base_seconds:
+        lockout_max_seconds = lockout_base_seconds
+    return LoginThrottlePolicy(
+        failure_limit=failure_limit,
+        failure_window_seconds=failure_window_seconds,
+        lockout_base_seconds=lockout_base_seconds,
+        lockout_max_seconds=lockout_max_seconds,
+    )
+
+
+def _normalize_login_identity(username: str, ip_address: str | None) -> tuple[str, str]:
+    """Normalizes username and source IP identity values used by throttle storage keys."""
+
+    normalized_username = normalize_username(username) or UNKNOWN_USERNAME_SUBJECT
+    normalized_ip = (ip_address or "").strip()[:64] or UNKNOWN_IP_SUBJECT
+    return normalized_username, normalized_ip
+
+
+def _identity_subjects(username: str, ip_address: str | None) -> tuple[tuple[str, str], tuple[str, str]]:
+    """Builds the username and IP throttle subject tuples for one login attempt."""
+
+    normalized_username, normalized_ip = _normalize_login_identity(username, ip_address)
+    return (
+        (USERNAME_SUBJECT_KIND, normalized_username),
+        (IP_SUBJECT_KIND, normalized_ip),
+    )
+
+
+def _failure_key(*, subject_kind: str, subject_value: str) -> str:
+    """Builds the Redis key used to track failed login counts for one subject."""
+
+    return f"dcm:auth-login:fail:{subject_kind}:{subject_value}"
+
+
+def _lock_key(*, subject_kind: str, subject_value: str) -> str:
+    """Builds the Redis key used to store active lockout state for one subject."""
+
+    return f"dcm:auth-login:lock:{subject_kind}:{subject_value}"
+
+
+def _next_lockout_seconds(*, failure_count: int, policy: LoginThrottlePolicy) -> int:
+    """Computes exponential lockout duration when failed attempts exceed configured limit."""
+
+    if failure_count <= policy.failure_limit:
+        return 0
+
+    additional_failures = failure_count - policy.failure_limit - 1
+    lockout_seconds = policy.lockout_base_seconds
+    while additional_failures > 0 and lockout_seconds < policy.lockout_max_seconds:
+        lockout_seconds = min(policy.lockout_max_seconds, lockout_seconds * 2)
+        additional_failures -= 1
+    return lockout_seconds
+
+
+def check_login_throttle(*, username: str, ip_address: str | None) -> LoginThrottleStatus:
+    """Returns active login throttle status for the username and source IP identity tuple."""
+
+    redis_client = get_redis()
+    try:
+        retry_after_seconds = 0
+        for subject_kind, subject_value in _identity_subjects(username, ip_address):
+            subject_ttl = int(redis_client.ttl(_lock_key(subject_kind=subject_kind, subject_value=subject_value)))
+            if subject_ttl == -1:
+                retry_after_seconds = max(retry_after_seconds, 1)
+            elif subject_ttl > 0:
+                retry_after_seconds = max(retry_after_seconds, subject_ttl)
+    except RedisError as error:
+        raise RuntimeError("Login throttle backend unavailable") from error
+
+    return LoginThrottleStatus(
+        is_throttled=retry_after_seconds > 0,
+        retry_after_seconds=retry_after_seconds,
+    )
+
+
+def record_failed_login_attempt(*, username: str, ip_address: str | None) -> int:
+    """Records one failed login attempt and returns active lockout seconds, if any."""
+
+    settings = get_settings()
+    policy = _resolve_policy(settings)
+    normalized_username, normalized_ip = _normalize_login_identity(username, ip_address)
+    redis_client = get_redis()
+
+    try:
+        highest_failure_count = 0
+        active_lockout_seconds = 0
+        for subject_kind, subject_value in (
+            (USERNAME_SUBJECT_KIND, normalized_username),
+            (IP_SUBJECT_KIND, normalized_ip),
+        ):
+            failure_key = _failure_key(subject_kind=subject_kind, subject_value=subject_value)
+            pipeline = redis_client.pipeline(transaction=True)
+            pipeline.incr(failure_key, 1)
+            pipeline.expire(failure_key, policy.failure_window_seconds + 5)
+            count_value, _ = pipeline.execute()
+            failure_count = int(count_value)
+            highest_failure_count = max(highest_failure_count, failure_count)
+
+            lockout_seconds = _next_lockout_seconds(failure_count=failure_count, policy=policy)
+            if lockout_seconds > 0:
+                redis_client.set(
+                    _lock_key(subject_kind=subject_kind, subject_value=subject_value),
+                    "1",
+                    ex=lockout_seconds,
+                )
+                active_lockout_seconds = max(active_lockout_seconds, lockout_seconds)
+    except RedisError as error:
+        raise RuntimeError("Login throttle backend unavailable") from error
+
+    logger.warning(
+        "Authentication login failure: username=%s ip=%s failed_attempts=%s lockout_seconds=%s",
+        normalized_username,
+        normalized_ip,
+        highest_failure_count,
+        active_lockout_seconds,
+    )
+    return active_lockout_seconds
+
+
+def clear_login_throttle(*, username: str, ip_address: str | None) -> None:
+    """Clears username and source-IP login throttle state after successful authentication."""
+
+    normalized_username, normalized_ip = _normalize_login_identity(username, ip_address)
+    redis_client = get_redis()
+    keys = [
+        _failure_key(subject_kind=USERNAME_SUBJECT_KIND, subject_value=normalized_username),
+        _lock_key(subject_kind=USERNAME_SUBJECT_KIND, subject_value=normalized_username),
+        _failure_key(subject_kind=IP_SUBJECT_KIND, subject_value=normalized_ip),
+        _lock_key(subject_kind=IP_SUBJECT_KIND, subject_value=normalized_ip),
+    ]
+    try:
+        redis_client.delete(*keys)
+    except RedisError as error:
+        raise RuntimeError("Login throttle backend unavailable") from error

backend/tests/test_security_controls.py

@@ -40,6 +40,48 @@ if "pydantic_settings" not in sys.modules:
 if "fastapi" not in sys.modules:
     fastapi_stub = ModuleType("fastapi")
 
+    class _APIRouter:
+        """Minimal APIRouter stand-in supporting decorator registration."""
+
+        def __init__(self, *args: object, **kwargs: object) -> None:
+            self.args = args
+            self.kwargs = kwargs
+
+        def post(self, *_args: object, **_kwargs: object):  # type: ignore[no-untyped-def]
+            """Returns no-op decorator for POST route declarations."""
+
+            def decorator(func):  # type: ignore[no-untyped-def]
+                return func
+
+            return decorator
+
+        def get(self, *_args: object, **_kwargs: object):  # type: ignore[no-untyped-def]
+            """Returns no-op decorator for GET route declarations."""
+
+            def decorator(func):  # type: ignore[no-untyped-def]
+                return func
+
+            return decorator
+
+        def patch(self, *_args: object, **_kwargs: object):  # type: ignore[no-untyped-def]
+            """Returns no-op decorator for PATCH route declarations."""
+
+            def decorator(func):  # type: ignore[no-untyped-def]
+                return func
+
+            return decorator
+
+        def delete(self, *_args: object, **_kwargs: object):  # type: ignore[no-untyped-def]
+            """Returns no-op decorator for DELETE route declarations."""
+
+            def decorator(func):  # type: ignore[no-untyped-def]
+                return func
+
+            return decorator
+
+    class _Request:
+        """Minimal request placeholder for route function import compatibility."""
+
     class _HTTPException(Exception):
         """Minimal HTTPException compatible with route dependency tests."""
 
@@ -54,6 +96,7 @@ if "fastapi" not in sys.modules:
 
         HTTP_401_UNAUTHORIZED = 401
         HTTP_403_FORBIDDEN = 403
+        HTTP_429_TOO_MANY_REQUESTS = 429
         HTTP_503_SERVICE_UNAVAILABLE = 503
 
     def _depends(dependency):  # type: ignore[no-untyped-def]
@@ -61,11 +104,52 @@ if "fastapi" not in sys.modules:
 
         return dependency
 
+    def _query(default=None, **_kwargs):  # type: ignore[no-untyped-def]
+        """Returns FastAPI-like query defaults for dependency-light route imports."""
+
+        return default
+
+    def _file(default=None, **_kwargs):  # type: ignore[no-untyped-def]
+        """Returns FastAPI-like file defaults for dependency-light route imports."""
+
+        return default
+
+    def _form(default=None, **_kwargs):  # type: ignore[no-untyped-def]
+        """Returns FastAPI-like form defaults for dependency-light route imports."""
+
+        return default
+
+    class _UploadFile:
+        """Minimal UploadFile placeholder for route import compatibility."""
+
+    fastapi_stub.APIRouter = _APIRouter
     fastapi_stub.Depends = _depends
+    fastapi_stub.File = _file
+    fastapi_stub.Form = _form
     fastapi_stub.HTTPException = _HTTPException
+    fastapi_stub.Query = _query
+    fastapi_stub.Request = _Request
+    fastapi_stub.UploadFile = _UploadFile
     fastapi_stub.status = _Status()
     sys.modules["fastapi"] = fastapi_stub
 
+if "fastapi.responses" not in sys.modules:
+    fastapi_responses_stub = ModuleType("fastapi.responses")
+
+    class _Response:
+        """Minimal response placeholder for route import compatibility."""
+
+    class _FileResponse(_Response):
+        """Minimal file response placeholder for route import compatibility."""
+
+    class _StreamingResponse(_Response):
+        """Minimal streaming response placeholder for route import compatibility."""
+
+    fastapi_responses_stub.Response = _Response
+    fastapi_responses_stub.FileResponse = _FileResponse
+    fastapi_responses_stub.StreamingResponse = _StreamingResponse
+    sys.modules["fastapi.responses"] = fastapi_responses_stub
+
 if "fastapi.security" not in sys.modules:
     fastapi_security_stub = ModuleType("fastapi.security")
 
@@ -238,8 +322,14 @@ if "app.services.handwriting_style" not in sys.modules:
 
         return None
 
+    def _delete_many_handwriting_style_documents(*_args: object, **_kwargs: object) -> None:
+        """No-op bulk style document delete stub for route import compatibility."""
+
+        return None
+
     handwriting_style_stub.assign_handwriting_style = _assign_handwriting_style
     handwriting_style_stub.delete_handwriting_style_document = _delete_handwriting_style_document
+    handwriting_style_stub.delete_many_handwriting_style_documents = _delete_many_handwriting_style_documents
     sys.modules["app.services.handwriting_style"] = handwriting_style_stub
 
 if "app.services.routing_pipeline" not in sys.modules:
@@ -274,10 +364,13 @@ if "app.services.routing_pipeline" not in sys.modules:
 from fastapi import HTTPException
 
 from app.api.auth import AuthContext, require_admin
+from app.api import routes_auth as auth_routes_module
+from app.api import routes_documents as documents_routes_module
 from app.core import config as config_module
 from app.models.auth import UserRole
 from app.models.processing_log import sanitize_processing_log_payload_value, sanitize_processing_log_text
 from app.schemas.processing_logs import ProcessingLogEntryResponse
+from app.services import auth_login_throttle as auth_login_throttle_module
 from app.services import extractor as extractor_module
 from app.worker import tasks as worker_tasks_module
 
@@ -328,6 +421,498 @@ class AuthDependencyTests(unittest.TestCase):
         self.assertEqual(resolved.role, UserRole.ADMIN)
 
 
+class DocumentCatalogVisibilityTests(unittest.TestCase):
+    """Verifies predefined tag and path discovery visibility by caller role."""
+
+    class _ScalarSequence:
+        """Provides SQLAlchemy-like scalar result chaining for route unit tests."""
+
+        def __init__(self, values: list[object]) -> None:
+            self._values = values
+
+        def scalars(self) -> "DocumentCatalogVisibilityTests._ScalarSequence":
+            """Returns self to emulate `.scalars().all()` call chains."""
+
+            return self
+
+        def all(self) -> list[object]:
+            """Returns deterministic sequence values for route helper queries."""
+
+            return list(self._values)
+
+    class _SessionStub:
+        """Returns a fixed scalar sequence for route metadata queries."""
+
+        def __init__(self, values: list[object]) -> None:
+            self._values = values
+
+        def execute(self, _statement: object) -> "DocumentCatalogVisibilityTests._ScalarSequence":
+            """Ignores query details and returns deterministic scalar sequence results."""
+
+            return DocumentCatalogVisibilityTests._ScalarSequence(self._values)
+
+    @staticmethod
+    def _auth_context(role: UserRole) -> AuthContext:
+        """Builds deterministic auth context fixtures for document discovery tests."""
+
+        return AuthContext(
+            user_id=uuid.uuid4(),
+            username=f"{role.value}-user",
+            role=role,
+            session_id=uuid.uuid4(),
+            expires_at=datetime.now(UTC),
+        )
+
+    def test_non_admin_only_receives_global_shared_predefined_tags_and_paths(self) -> None:
+        """User role receives only globally shared predefined values in discovery responses."""
+
+        session = self._SessionStub(
+            values=[
+                ["owner-tag", ""],
+                ["owner-only-tag"],
+            ]
+        )
+        predefined_tags = [
+            {"value": "SharedTag", "global_shared": True},
+            {"value": "InternalTag", "global_shared": False},
+            {"value": "ImplicitPrivateTag"},
+        ]
+        predefined_paths = [
+            {"value": "Shared/Path", "global_shared": True},
+            {"value": "Internal/Path", "global_shared": False},
+            {"value": "Implicit/Private"},
+        ]
+
+        with (
+            patch.object(documents_routes_module, "read_predefined_tags_settings", return_value=predefined_tags),
+            patch.object(documents_routes_module, "read_predefined_paths_settings", return_value=predefined_paths),
+        ):
+            tags_response = documents_routes_module.list_tags(
+                include_trashed=False,
+                auth_context=self._auth_context(UserRole.USER),
+                session=session,
+            )
+            paths_response = documents_routes_module.list_paths(
+                include_trashed=False,
+                auth_context=self._auth_context(UserRole.USER),
+                session=self._SessionStub(values=["Owner/Path"]),
+            )
+
+        self.assertEqual(tags_response["tags"], ["SharedTag", "owner-only-tag", "owner-tag"])
+        self.assertEqual(paths_response["paths"], ["Owner/Path", "Shared/Path"])
+
+    def test_admin_receives_full_predefined_tags_and_paths_catalog(self) -> None:
+        """Admin role receives full predefined values regardless of global-sharing scope."""
+
+        predefined_tags = [
+            {"value": "SharedTag", "global_shared": True},
+            {"value": "InternalTag", "global_shared": False},
+            {"value": "ImplicitPrivateTag"},
+        ]
+        predefined_paths = [
+            {"value": "Shared/Path", "global_shared": True},
+            {"value": "Internal/Path", "global_shared": False},
+            {"value": "Implicit/Private"},
+        ]
+
+        with (
+            patch.object(documents_routes_module, "read_predefined_tags_settings", return_value=predefined_tags),
+            patch.object(documents_routes_module, "read_predefined_paths_settings", return_value=predefined_paths),
+        ):
+            tags_response = documents_routes_module.list_tags(
+                include_trashed=False,
+                auth_context=self._auth_context(UserRole.ADMIN),
+                session=self._SessionStub(values=[["admin-tag"]]),
+            )
+            paths_response = documents_routes_module.list_paths(
+                include_trashed=False,
+                auth_context=self._auth_context(UserRole.ADMIN),
+                session=self._SessionStub(values=["Admin/Path"]),
+            )
+
+        self.assertEqual(
+            tags_response["tags"],
+            ["ImplicitPrivateTag", "InternalTag", "SharedTag", "admin-tag"],
+        )
+        self.assertEqual(
+            paths_response["paths"],
+            ["Admin/Path", "Implicit/Private", "Internal/Path", "Shared/Path"],
+        )
+
+
+class _FakeRedisPipeline:
+    """Provides deterministic Redis pipeline behavior for login throttle tests."""
+
+    def __init__(self, redis_client: "_FakeRedis") -> None:
+        self._redis_client = redis_client
+        self._operations: list[tuple[str, tuple[object, ...]]] = []
+
+    def incr(self, key: str, amount: int) -> "_FakeRedisPipeline":
+        """Queues one counter increment operation for pipeline execution."""
+
+        self._operations.append(("incr", (key, amount)))
+        return self
+
+    def expire(self, key: str, ttl_seconds: int) -> "_FakeRedisPipeline":
+        """Queues one key expiration operation for pipeline execution."""
+
+        self._operations.append(("expire", (key, ttl_seconds)))
+        return self
+
+    def execute(self) -> list[object]:
+        """Executes queued operations in order and returns Redis-like result values."""
+
+        results: list[object] = []
+        for operation, arguments in self._operations:
+            if operation == "incr":
+                key, amount = arguments
+                previous = int(self._redis_client.values.get(str(key), 0))
+                updated = previous + int(amount)
+                self._redis_client.values[str(key)] = updated
+                results.append(updated)
+            elif operation == "expire":
+                key, ttl_seconds = arguments
+                self._redis_client.ttl_seconds[str(key)] = int(ttl_seconds)
+                results.append(True)
+        return results
+
+
+class _FakeRedis:
+    """In-memory Redis replacement with TTL behavior needed by throttle tests."""
+
+    def __init__(self) -> None:
+        self.values: dict[str, object] = {}
+        self.ttl_seconds: dict[str, int] = {}
+
+    def pipeline(self, transaction: bool = True) -> _FakeRedisPipeline:
+        """Creates a fake transaction pipeline for grouped increment operations."""
+
+        _ = transaction
+        return _FakeRedisPipeline(self)
+
+    def set(self, key: str, value: str, ex: int | None = None) -> bool:
+        """Stores key values and optional TTL metadata used by lockout keys."""
+
+        self.values[key] = value
+        if ex is not None:
+            self.ttl_seconds[key] = int(ex)
+        return True
+
+    def ttl(self, key: str) -> int:
+        """Returns TTL for existing keys or Redis-compatible missing-key indicator."""
+
+        return int(self.ttl_seconds.get(key, -2))
+
+    def delete(self, *keys: str) -> int:
+        """Deletes keys and returns number of removed entries."""
+
+        removed_count = 0
+        for key in keys:
+            if key in self.values:
+                self.values.pop(key, None)
+                removed_count += 1
+            self.ttl_seconds.pop(key, None)
+        return removed_count
+
+
+def _login_throttle_settings(
+    *,
+    failure_limit: int = 2,
+    failure_window_seconds: int = 60,
+    lockout_base_seconds: int = 10,
+    lockout_max_seconds: int = 40,
+) -> SimpleNamespace:
+    """Builds deterministic login-throttle settings for service-level unit coverage."""
+
+    return SimpleNamespace(
+        auth_login_failure_limit=failure_limit,
+        auth_login_failure_window_seconds=failure_window_seconds,
+        auth_login_lockout_base_seconds=lockout_base_seconds,
+        auth_login_lockout_max_seconds=lockout_max_seconds,
+    )
+
+
+class AuthLoginThrottleServiceTests(unittest.TestCase):
+    """Verifies login throttle lockout progression, cap behavior, and clear semantics."""
+
+    def test_failed_attempts_trigger_lockout_after_limit(self) -> None:
+        """Failed attempts beyond configured limit activate login lockouts."""
+
+        fake_redis = _FakeRedis()
+        with (
+            patch.object(
+                auth_login_throttle_module,
+                "get_settings",
+                return_value=_login_throttle_settings(failure_limit=2, lockout_base_seconds=12),
+            ),
+            patch.object(auth_login_throttle_module, "get_redis", return_value=fake_redis),
+        ):
+            self.assertEqual(
+                auth_login_throttle_module.record_failed_login_attempt(
+                    username="admin",
+                    ip_address="203.0.113.10",
+                ),
+                0,
+            )
+            self.assertEqual(
+                auth_login_throttle_module.record_failed_login_attempt(
+                    username="admin",
+                    ip_address="203.0.113.10",
+                ),
+                0,
+            )
+            lockout_seconds = auth_login_throttle_module.record_failed_login_attempt(
+                username="admin",
+                ip_address="203.0.113.10",
+            )
+            status = auth_login_throttle_module.check_login_throttle(
+                username="admin",
+                ip_address="203.0.113.10",
+            )
+
+        self.assertEqual(lockout_seconds, 12)
+        self.assertTrue(status.is_throttled)
+        self.assertEqual(status.retry_after_seconds, 12)
+
+    def test_lockout_duration_escalates_and_respects_max_cap(self) -> None:
+        """Repeated failures after threshold double lockout duration up to configured maximum."""
+
+        fake_redis = _FakeRedis()
+        with (
+            patch.object(
+                auth_login_throttle_module,
+                "get_settings",
+                return_value=_login_throttle_settings(
+                    failure_limit=1,
+                    lockout_base_seconds=10,
+                    lockout_max_seconds=25,
+                ),
+            ),
+            patch.object(auth_login_throttle_module, "get_redis", return_value=fake_redis),
+        ):
+            first_lockout = auth_login_throttle_module.record_failed_login_attempt(
+                username="admin",
+                ip_address="198.51.100.15",
+            )
+            second_lockout = auth_login_throttle_module.record_failed_login_attempt(
+                username="admin",
+                ip_address="198.51.100.15",
+            )
+            third_lockout = auth_login_throttle_module.record_failed_login_attempt(
+                username="admin",
+                ip_address="198.51.100.15",
+            )
+            fourth_lockout = auth_login_throttle_module.record_failed_login_attempt(
+                username="admin",
+                ip_address="198.51.100.15",
+            )
+
+        self.assertEqual(first_lockout, 0)
+        self.assertEqual(second_lockout, 10)
+        self.assertEqual(third_lockout, 20)
+        self.assertEqual(fourth_lockout, 25)
+
+    def test_clear_login_throttle_removes_active_lockout_state(self) -> None:
+        """Successful login clears active lockout keys for username and IP subjects."""
+
+        fake_redis = _FakeRedis()
+        with (
+            patch.object(
+                auth_login_throttle_module,
+                "get_settings",
+                return_value=_login_throttle_settings(
+                    failure_limit=1,
+                    lockout_base_seconds=15,
+                    lockout_max_seconds=30,
+                ),
+            ),
+            patch.object(auth_login_throttle_module, "get_redis", return_value=fake_redis),
+        ):
+            auth_login_throttle_module.record_failed_login_attempt(
+                username="admin",
+                ip_address="192.0.2.20",
+            )
+            auth_login_throttle_module.record_failed_login_attempt(
+                username="admin",
+                ip_address="192.0.2.20",
+            )
+            throttled_before_clear = auth_login_throttle_module.check_login_throttle(
+                username="admin",
+                ip_address="192.0.2.20",
+            )
+            auth_login_throttle_module.clear_login_throttle(
+                username="admin",
+                ip_address="192.0.2.20",
+            )
+            throttled_after_clear = auth_login_throttle_module.check_login_throttle(
+                username="admin",
+                ip_address="192.0.2.20",
+            )
+
+        self.assertTrue(throttled_before_clear.is_throttled)
+        self.assertFalse(throttled_after_clear.is_throttled)
+        self.assertEqual(throttled_after_clear.retry_after_seconds, 0)
+
+    def test_backend_errors_raise_runtime_error(self) -> None:
+        """Redis backend failures are surfaced as RuntimeError for caller fail-closed handling."""
+
+        class _BrokenRedis:
+            """Raises RedisError for all Redis interactions used by login throttle service."""
+
+            def ttl(self, _key: str) -> int:
+                raise auth_login_throttle_module.RedisError("redis unavailable")
+
+        with patch.object(auth_login_throttle_module, "get_redis", return_value=_BrokenRedis()):
+            with self.assertRaises(RuntimeError):
+                auth_login_throttle_module.check_login_throttle(
+                    username="admin",
+                    ip_address="203.0.113.88",
+                )
+
+
+class AuthLoginRouteThrottleTests(unittest.TestCase):
+    """Verifies `/auth/login` route throttle responses and success-flow state clearing."""
+
+    class _SessionStub:
+        """Tracks commit calls for route-level login tests without database dependencies."""
+
+        def __init__(self) -> None:
+            self.commit_count = 0
+
+        def commit(self) -> None:
+            """Records one commit invocation."""
+
+            self.commit_count += 1
+
+    @staticmethod
+    def _response_stub() -> SimpleNamespace:
+        """Builds a minimal response object for direct route invocation."""
+
+        return SimpleNamespace(
+            set_cookie=lambda *_args, **_kwargs: None,
+            delete_cookie=lambda *_args, **_kwargs: None,
+        )
+
+    @staticmethod
+    def _request_stub(ip_address: str = "203.0.113.2", user_agent: str = "unit-test") -> SimpleNamespace:
+        """Builds request-like object containing client host and user-agent header fields."""
+
+        return SimpleNamespace(
+            client=SimpleNamespace(host=ip_address),
+            headers={"user-agent": user_agent},
+        )
+
+    def test_login_rejects_when_precheck_reports_active_throttle(self) -> None:
+        """Pre-auth throttle checks return a stable 429 response without credential lookup."""
+
+        payload = auth_routes_module.AuthLoginRequest(username="admin", password="bad-password")
+        session = self._SessionStub()
+        throttled = auth_login_throttle_module.LoginThrottleStatus(
+            is_throttled=True,
+            retry_after_seconds=21,
+        )
+        with (
+            patch.object(auth_routes_module, "check_login_throttle", return_value=throttled),
+            patch.object(auth_routes_module, "authenticate_user") as authenticate_mock,
+        ):
+            with self.assertRaises(HTTPException) as raised:
+                auth_routes_module.login(
+                    payload=payload,
+                    request=self._request_stub(),
+                    response=self._response_stub(),
+                    session=session,
+                )
+        self.assertEqual(raised.exception.status_code, 429)
+        self.assertEqual(raised.exception.detail, auth_routes_module.LOGIN_THROTTLED_DETAIL)
+        self.assertEqual(raised.exception.headers.get("Retry-After"), "21")
+        authenticate_mock.assert_not_called()
+        self.assertEqual(session.commit_count, 0)
+
+    def test_login_returns_throttle_response_when_failure_crosses_limit(self) -> None:
+        """Failed credentials return stable 429 response once lockout threshold is crossed."""
+
+        payload = auth_routes_module.AuthLoginRequest(username="admin", password="bad-password")
+        session = self._SessionStub()
+        with (
+            patch.object(
+                auth_routes_module,
+                "check_login_throttle",
+                return_value=auth_login_throttle_module.LoginThrottleStatus(
+                    is_throttled=False,
+                    retry_after_seconds=0,
+                ),
+            ),
+            patch.object(auth_routes_module, "authenticate_user", return_value=None),
+            patch.object(auth_routes_module, "record_failed_login_attempt", return_value=30),
+        ):
+            with self.assertRaises(HTTPException) as raised:
+                auth_routes_module.login(
+                    payload=payload,
+                    request=self._request_stub(),
+                    response=self._response_stub(),
+                    session=session,
+                )
+        self.assertEqual(raised.exception.status_code, 429)
+        self.assertEqual(raised.exception.detail, auth_routes_module.LOGIN_THROTTLED_DETAIL)
+        self.assertEqual(raised.exception.headers.get("Retry-After"), "30")
+        self.assertEqual(session.commit_count, 0)
+
+    def test_login_clears_throttle_state_after_successful_authentication(self) -> None:
+        """Successful login clears throttle state and commits issued session token."""
+
+        payload = auth_routes_module.AuthLoginRequest(username="admin", password="correct-password")
+        session = self._SessionStub()
+        fake_user = SimpleNamespace(
+            id=uuid.uuid4(),
+            username="admin",
+            role=UserRole.ADMIN,
+        )
+        fake_session = SimpleNamespace(
+            token="session-token",
+            expires_at=datetime.now(UTC),
+        )
+        with (
+            patch.object(
+                auth_routes_module,
+                "check_login_throttle",
+                return_value=auth_login_throttle_module.LoginThrottleStatus(
+                    is_throttled=False,
+                    retry_after_seconds=0,
+                ),
+            ),
+            patch.object(auth_routes_module, "authenticate_user", return_value=fake_user),
+            patch.object(auth_routes_module, "clear_login_throttle") as clear_mock,
+            patch.object(auth_routes_module, "issue_user_session", return_value=fake_session),
+        ):
+            response = auth_routes_module.login(
+                payload=payload,
+                request=self._request_stub(),
+                response=self._response_stub(),
+                session=session,
+            )
+        self.assertEqual(response.access_token, "session-token")
+        self.assertEqual(response.user.username, "admin")
+        clear_mock.assert_called_once()
+        self.assertEqual(session.commit_count, 1)
+
+    def test_login_returns_503_when_throttle_backend_is_unavailable(self) -> None:
+        """Throttle backend errors fail closed with a deterministic 503 login response."""
+
+        payload = auth_routes_module.AuthLoginRequest(username="admin", password="password")
+        session = self._SessionStub()
+        with patch.object(auth_routes_module, "check_login_throttle", side_effect=RuntimeError("redis down")):
+            with self.assertRaises(HTTPException) as raised:
+                auth_routes_module.login(
+                    payload=payload,
+                    request=self._request_stub(),
+                    response=self._response_stub(),
+                    session=session,
+                )
+        self.assertEqual(raised.exception.status_code, 503)
+        self.assertEqual(raised.exception.detail, auth_routes_module.LOGIN_RATE_LIMITER_UNAVAILABLE_DETAIL)
+        self.assertEqual(session.commit_count, 0)
+
+
 class ProviderBaseUrlValidationTests(unittest.TestCase):
     """Verifies allowlist, scheme, and private-network SSRF protections."""
 

backend/tests/test_upload_request_size_middleware.py

@@ -29,6 +29,7 @@ def _install_main_import_stubs() -> dict[str, ModuleType | None]:
             "app.core.config",
             "app.db.base",
             "app.services.app_settings",
+            "app.services.authentication",
             "app.services.handwriting_style",
             "app.services.storage",
             "app.services.typesense_index",
@@ -139,6 +140,14 @@ def _install_main_import_stubs() -> dict[str, ModuleType | None]:
     app_settings_stub.ensure_app_settings = ensure_app_settings
     sys.modules["app.services.app_settings"] = app_settings_stub
 
+    authentication_stub = ModuleType("app.services.authentication")
+
+    def ensure_bootstrap_users() -> None:
+        """No-op bootstrap user initializer for middleware scope tests."""
+
+    authentication_stub.ensure_bootstrap_users = ensure_bootstrap_users
+    sys.modules["app.services.authentication"] = authentication_stub
+
     handwriting_style_stub = ModuleType("app.services.handwriting_style")
 
     def ensure_handwriting_style_collection() -> None:

doc/README.md

@@ -6,7 +6,7 @@ This directory contains technical documentation for DMS.
 
 - `../README.md` - project overview, setup, and quick operations
 - `architecture-overview.md` - backend, frontend, and infrastructure architecture
-- `api-contract.md` - API endpoint contract grouped by route module, including session auth, role and ownership scope, upload limits, and settings or processing-log security constraints
+- `api-contract.md` - API endpoint contract grouped by route module, including session auth, login throttle responses, role and ownership scope, upload limits, and settings or processing-log security constraints
 - `data-model-reference.md` - database entity definitions and lifecycle states
 - `operations-and-configuration.md` - runtime operations, hardened compose defaults, DEV and LIVE security values, and persisted settings configuration behavior
 - `frontend-design-foundation.md` - frontend visual system, tokens, UI implementation rules, authenticated media delivery under session auth, processing-log timeline behavior, and settings helper-copy guidance

doc/api-contract.md

@@ -13,10 +13,12 @@ Primary implementation modules:
 
 ## Authentication And Authorization
 
-- Authentication is session-based bearer auth.
+- Authentication is cookie-based session auth with a server-issued hashed session token.
 - Clients authenticate with `POST /auth/login` using username and password.
-- Backend issues per-user bearer session tokens and stores hashed session state server-side.
-- Clients send issued tokens as `Authorization: Bearer <token>`.
+- Backend issues a server-stored session token and sets `HttpOnly` `dcm_session` and readable `dcm_csrf` cookies.
+- Login brute-force protection enforces Redis-backed throttle checks keyed by username and source IP.
+- State-changing requests from browser clients must send `x-csrf-token: <dcm_csrf>` in request headers (double-submit pattern).
+- For non-browser API clients, the optional `Authorization: Bearer <token>` path remains supported when the token is sent explicitly.
 - `GET /auth/me` returns current identity and role.
 - `POST /auth/logout` revokes current session token.
 
@@ -35,6 +37,10 @@ Ownership rules:
 - `POST /auth/login`
   - Body model: `AuthLoginRequest`
   - Response model: `AuthLoginResponse`
+  - Additional responses:
+    - `401` for invalid credentials
+    - `429` for throttled login attempts, with stable message and `Retry-After` header
+    - `503` when the login rate-limiter backend is unavailable
 - `GET /auth/me`
   - Response model: `AuthSessionResponse`
 - `POST /auth/logout`
@@ -56,9 +62,15 @@ Ownership rules:
 - `GET /documents/tags`
   - Query: `include_trashed`
   - Response: `{ "tags": string[] }`
+  - Behavior:
+    - all document-assigned tags visible to caller scope are included
+    - predefined tags are role-filtered: `admin` receives full catalog, `user` receives only entries with `global_shared=true`
 - `GET /documents/paths`
   - Query: `include_trashed`
   - Response: `{ "paths": string[] }`
+  - Behavior:
+    - all document-assigned logical paths visible to caller scope are included
+    - predefined paths are role-filtered: `admin` receives full catalog, `user` receives only entries with `global_shared=true`
 - `GET /documents/types`
   - Query: `include_trashed`
   - Response: `{ "types": string[] }`

doc/frontend-design-foundation.md

@@ -52,7 +52,7 @@ Do not hardcode new palette or spacing values in component styles when a token a
 ## Authenticated Media Delivery
 
 - Document previews and thumbnails must load through authenticated fetch flows in `frontend/src/lib/api.ts`, then render via temporary object URLs.
-- Runtime auth uses server-issued per-user session tokens persisted with `setRuntimeApiToken` and read by `getRuntimeApiToken`.
+- Runtime auth is cookie-backed; valid sessions are reused by browser reload and tab reuse while the `dcm_session` cookie remains valid.
 - Static build-time token distribution is not supported.
 - Direct `window.open` calls for protected media endpoints are not allowed because browser navigation requests do not include the API token header.
 - Download actions for original files and markdown exports must use authenticated blob fetches plus controlled browser download triggers.

doc/operations-and-configuration.md

@@ -45,13 +45,18 @@ docker compose logs -f
 ## Authentication Model
 
 - Legacy shared build-time frontend token behavior was removed.
-- API now uses server-issued per-user bearer sessions.
+- API now uses server-issued sessions that are stored in HttpOnly cookies (`dcm_session`) with a separate CSRF cookie (`dcm_csrf`).
 - Bootstrap users are provisioned from environment:
   - `AUTH_BOOTSTRAP_ADMIN_USERNAME`
   - `AUTH_BOOTSTRAP_ADMIN_PASSWORD`
   - optional `AUTH_BOOTSTRAP_USER_USERNAME`
   - optional `AUTH_BOOTSTRAP_USER_PASSWORD`
-- Frontend signs in through `/api/v1/auth/login` and stores issued session token in browser session storage.
+- Login brute-force protection is enabled by default and keyed by username and source IP:
+  - `AUTH_LOGIN_FAILURE_LIMIT`
+  - `AUTH_LOGIN_FAILURE_WINDOW_SECONDS`
+  - `AUTH_LOGIN_LOCKOUT_BASE_SECONDS`
+  - `AUTH_LOGIN_LOCKOUT_MAX_SECONDS`
+  - Frontend signs in through `/api/v1/auth/login` and relies on browser session persistence for valid cookie-backed sessions.
 
 ## DEV And LIVE Configuration Matrix
 
@@ -67,6 +72,10 @@ Use `.env.example` as baseline. The table below documents user-managed settings
 | `REDIS_URL` | `redis://:<password>@redis:6379/0` in isolated local network | `rediss://:<password>@redis.internal:6379/0` |
 | `REDIS_SECURITY_MODE` | `compat` or `auto` | `strict` |
 | `REDIS_TLS_MODE` | `allow_insecure` or `auto` | `required` |
+| `AUTH_LOGIN_FAILURE_LIMIT` | default `5` | tune to identity-protection policy and support requirements |
+| `AUTH_LOGIN_FAILURE_WINDOW_SECONDS` | default `900` | tune to identity-protection policy and support requirements |
+| `AUTH_LOGIN_LOCKOUT_BASE_SECONDS` | default `30` | tune to identity-protection policy and support requirements |
+| `AUTH_LOGIN_LOCKOUT_MAX_SECONDS` | default `900` | tune to identity-protection policy and support requirements |
 | `PROVIDER_BASE_URL_ALLOW_HTTP` | `true` only when intentionally testing local HTTP provider endpoints | `false` |
 | `PROVIDER_BASE_URL_ALLOW_PRIVATE_NETWORK` | `true` only for trusted local development targets | `false` |
 | `PROVIDER_BASE_URL_ALLOWLIST` | allow needed test hosts | explicit production allowlist, for example `["api.openai.com"]` |
@@ -89,7 +98,7 @@ Recommended LIVE pattern:
 2. Keep container published ports bound to localhost or internal network.
 3. Set `PUBLIC_BASE_URL` and `VITE_API_BASE` to final HTTPS URLs.
 4. Set `CORS_ORIGINS` to exact HTTPS frontend origins.
-5. Credentialed CORS is intentionally disabled in application code for bearer-header auth.
+5. Credentialed CORS is enabled and constrained for cookie-based sessions with strict origin allowlists.
 
 ## Security Controls
 
@@ -99,6 +108,7 @@ Recommended LIVE pattern:
   - legacy `enc-v1` payloads are read for backward compatibility
   - new writes use `enc-v2`
 - Processing logs default to metadata-only persistence.
+- Login endpoint applies escalating temporary lockout on repeated failed credentials using Redis-backed subject keys for username and source IP.
 - Markdown export enforces:
   - max document count
   - max total markdown bytes
@@ -109,7 +119,7 @@ Recommended LIVE pattern:
 ## Frontend Runtime
 
 - Frontend no longer consumes `VITE_API_TOKEN`.
-- Session token storage key is `dcm.access_token` in browser session storage.
+- Session authentication is cookie-based; browser reloads and new tabs can reuse an active session until it expires or is revoked.
 - Protected media and file download flows still use authenticated fetch plus blob/object URL handling.
 
 ## Validation Checklist

docker-compose.yml

@@ -47,6 +47,10 @@ services:
       AUTH_BOOTSTRAP_ADMIN_PASSWORD: ${AUTH_BOOTSTRAP_ADMIN_PASSWORD:?AUTH_BOOTSTRAP_ADMIN_PASSWORD must be set}
       AUTH_BOOTSTRAP_USER_USERNAME: ${AUTH_BOOTSTRAP_USER_USERNAME:-}
       AUTH_BOOTSTRAP_USER_PASSWORD: ${AUTH_BOOTSTRAP_USER_PASSWORD:-}
+      AUTH_LOGIN_FAILURE_LIMIT: ${AUTH_LOGIN_FAILURE_LIMIT:-5}
+      AUTH_LOGIN_FAILURE_WINDOW_SECONDS: ${AUTH_LOGIN_FAILURE_WINDOW_SECONDS:-900}
+      AUTH_LOGIN_LOCKOUT_BASE_SECONDS: ${AUTH_LOGIN_LOCKOUT_BASE_SECONDS:-30}
+      AUTH_LOGIN_LOCKOUT_MAX_SECONDS: ${AUTH_LOGIN_LOCKOUT_MAX_SECONDS:-900}
       APP_SETTINGS_ENCRYPTION_KEY: ${APP_SETTINGS_ENCRYPTION_KEY:?APP_SETTINGS_ENCRYPTION_KEY must be set}
       PROVIDER_BASE_URL_ALLOWLIST: '${PROVIDER_BASE_URL_ALLOWLIST:-[]}'
       PROVIDER_BASE_URL_ALLOW_HTTP: ${PROVIDER_BASE_URL_ALLOW_HTTP:-true}

frontend/src/App.tsx

@@ -20,7 +20,6 @@ import {
   deleteDocument,
   exportContentsMarkdown,
   getCurrentAuthSession,
-  getRuntimeApiToken,
   getAppSettings,
   listDocuments,
   listPaths,
@@ -30,7 +29,6 @@ import {
   loginWithPassword,
   logoutCurrentSession,
   resetAppSettings,
-  setRuntimeApiToken,
   searchDocuments,
   trashDocument,
   updateAppSettings,
@@ -161,21 +159,19 @@ export default function App(): JSX.Element {
   }, []);
 
   /**
-   * Exchanges submitted credentials for server-issued bearer session and activates app shell.
+   * Exchanges submitted credentials for a server-issued session and activates the app shell.
    */
   const handleLogin = useCallback(async (username: string, password: string): Promise<void> => {
     setIsAuthenticating(true);
     setAuthError(null);
     try {
       const payload = await loginWithPassword(username, password);
-      setRuntimeApiToken(payload.access_token);
       setAuthUser(payload.user);
       setAuthPhase('authenticated');
       setError(null);
     } catch (caughtError) {
       const message = caughtError instanceof Error ? caughtError.message : 'Login failed';
       setAuthError(message);
-      setRuntimeApiToken(null);
       setAuthUser(null);
       setAuthPhase('unauthenticated');
       resetApplicationState();
@@ -192,7 +188,6 @@ export default function App(): JSX.Element {
     try {
       await logoutCurrentSession();
     } catch {}
-    setRuntimeApiToken(null);
     setAuthUser(null);
     setAuthError(null);
     setAuthPhase('unauthenticated');
@@ -303,13 +298,6 @@ export default function App(): JSX.Element {
   }, [isAdmin]);
 
   useEffect(() => {
-    const existingToken = getRuntimeApiToken();
-    if (!existingToken) {
-      setAuthPhase('unauthenticated');
-      setAuthUser(null);
-      return;
-    }
-
     const resolveSession = async (): Promise<void> => {
       try {
         const sessionPayload = await getCurrentAuthSession();
@@ -317,7 +305,6 @@ export default function App(): JSX.Element {
         setAuthError(null);
         setAuthPhase('authenticated');
       } catch {
-        setRuntimeApiToken(null);
         setAuthUser(null);
         setAuthPhase('unauthenticated');
         resetApplicationState();

frontend/src/components/LoginScreen.tsx

@@ -11,7 +11,7 @@ interface LoginScreenProps {
 }
 
 /**
- * Renders credential form used to issue per-user API bearer sessions.
+ * Renders credential form used to issue per-user API sessions.
  */
 export default function LoginScreen({
   error,

frontend/src/lib/api.test.ts

@@ -5,10 +5,8 @@ import {
   getCurrentAuthSession,
   getDocumentPreviewBlob,
   getDocumentThumbnailBlob,
-  getRuntimeApiToken,
   loginWithPassword,
   logoutCurrentSession,
-  setRuntimeApiToken,
   updateDocumentMetadata,
 } from './api.ts';
 
@@ -48,53 +46,23 @@ function toRequestUrl(input: RequestInfo | URL): string {
   return input.url;
 }
 
-/**
- * Creates a minimal session storage implementation for Node-based tests.
- */
-function createMemorySessionStorage(): Storage {
-  const values = new Map<string, string>();
-  return {
-    get length(): number {
-      return values.size;
-    },
-    clear(): void {
-      values.clear();
-    },
-    getItem(key: string): string | null {
-      return values.has(key) ? values.get(key) ?? null : null;
-    },
-    key(index: number): string | null {
-      return Array.from(values.keys())[index] ?? null;
-    },
-    removeItem(key: string): void {
-      values.delete(key);
-    },
-    setItem(key: string, value: string): void {
-      values.set(key, String(value));
-    },
-  };
-}
-
 /**
  * Runs API helper tests for authenticated media and auth session workflows.
  */
 async function runApiTests(): Promise<void> {
   const originalFetch = globalThis.fetch;
-  const sessionStorageDescriptor = Object.getOwnPropertyDescriptor(globalThis, 'sessionStorage');
+  const globalWithDocument = globalThis as typeof globalThis & { document?: { cookie?: string } };
+  const originalDocument = globalWithDocument.document;
 
   try {
-    Object.defineProperty(globalThis, 'sessionStorage', {
-      configurable: true,
-      writable: true,
-      value: createMemorySessionStorage(),
-    });
-    setRuntimeApiToken(null);
-
     const requestUrls: string[] = [];
     const requestAuthHeaders: Array<string | null> = [];
+    const requestCsrfHeaders: Array<string | null> = [];
     globalThis.fetch = (async (input: RequestInfo | URL, init?: RequestInit): Promise<Response> => {
       requestUrls.push(toRequestUrl(input));
-      requestAuthHeaders.push(new Headers(init?.headers).get('Authorization'));
+      const normalizedHeaders = new Headers(init?.headers);
+      requestAuthHeaders.push(normalizedHeaders.get('Authorization'));
+      requestCsrfHeaders.push(normalizedHeaders.get('x-csrf-token'));
       return new Response('preview-bytes', { status: 200 });
     }) as typeof fetch;
 
@@ -113,27 +81,26 @@ async function runApiTests(): Promise<void> {
     );
     assert(requestAuthHeaders[0] === null, `Expected no auth header for thumbnail request, got "${requestAuthHeaders[0]}"`);
     assert(requestAuthHeaders[1] === null, `Expected no auth header for preview request, got "${requestAuthHeaders[1]}"`);
+    assert(requestCsrfHeaders[0] === null, `Expected no CSRF header for thumbnail request, got "${requestCsrfHeaders[0]}"`);
+    assert(requestCsrfHeaders[1] === null, `Expected no CSRF header for preview request, got "${requestCsrfHeaders[1]}"`);
 
-    setRuntimeApiToken('session-user-token');
-    assert(getRuntimeApiToken() === 'session-user-token', 'Expected session token readback to match persisted token');
-    globalThis.fetch = (async (_input: RequestInfo | URL, init?: RequestInit): Promise<Response> => {
-      const authHeader = new Headers(init?.headers).get('Authorization');
-      assert(authHeader === 'Bearer session-user-token', `Expected session token auth header, got "${authHeader}"`);
-      return new Response('preview-bytes', { status: 200 });
-    }) as typeof fetch;
-    await getDocumentPreviewBlob('doc-session-auth');
-
-    let mergedContentType: string | null = null;
-    let mergedAuthorization: string | null = null;
+    globalWithDocument.document = {
+      cookie: 'dcm_csrf=csrf-session-token',
+    };
+    let metadataCsrfHeader: string | null = null;
+    let metadataContentType: string | null = null;
+    let metadataAuthHeader: string | null = null;
     globalThis.fetch = (async (_input: RequestInfo | URL, init?: RequestInit): Promise<Response> => {
       const headers = new Headers(init?.headers);
-      mergedContentType = headers.get('Content-Type');
-      mergedAuthorization = headers.get('Authorization');
+      metadataCsrfHeader = headers.get('x-csrf-token');
+      metadataAuthHeader = headers.get('Authorization');
+      metadataContentType = headers.get('Content-Type');
       return new Response('{}', { status: 200 });
     }) as typeof fetch;
     await updateDocumentMetadata('doc-headers', { original_filename: 'renamed.pdf' });
-    assert(mergedContentType === 'application/json', `Expected JSON content type to be preserved, got "${mergedContentType}"`);
-    assert(mergedAuthorization === 'Bearer session-user-token', `Expected auth header, got "${mergedAuthorization}"`);
+    assert(metadataContentType === 'application/json', `Expected JSON content type to be preserved, got "${metadataContentType}"`);
+    assert(metadataAuthHeader === null, `Expected no auth header, got "${metadataAuthHeader}"`);
+    assert(metadataCsrfHeader === 'csrf-session-token', `Expected CSRF header, got "${metadataCsrfHeader}"`);
 
     globalThis.fetch = (async (): Promise<Response> => {
       return new Response(
@@ -202,13 +169,12 @@ async function runApiTests(): Promise<void> {
 
     await assertRejects(async () => downloadDocumentContentMarkdown('doc-4'), 'Failed to download document markdown');
   } finally {
-    setRuntimeApiToken(null);
-    if (sessionStorageDescriptor) {
-      Object.defineProperty(globalThis, 'sessionStorage', sessionStorageDescriptor);
-    } else {
-      delete (globalThis as { sessionStorage?: Storage }).sessionStorage;
-    }
     globalThis.fetch = originalFetch;
+    if (originalDocument !== undefined) {
+      globalWithDocument.document = originalDocument;
+    } else {
+      delete globalWithDocument.document;
+    }
   }
 }
 

frontend/src/lib/api.ts

@@ -36,90 +36,69 @@ function resolveApiBase(): string {
 const API_BASE = resolveApiBase();
 
 /**
- * Session storage key used for per-user runtime token persistence.
+ * CSRF cookie contract used by authenticated requests.
  */
-export const API_TOKEN_RUNTIME_STORAGE_KEY = 'dcm.access_token';
+const CSRF_COOKIE_NAME = "dcm_csrf";
+const CSRF_HEADER_NAME = "x-csrf-token";
+const CSRF_SAFE_METHODS = new Set(["GET", "HEAD", "OPTIONS"]);
 
 type ApiRequestInit = Omit<RequestInit, 'headers'> & { headers?: HeadersInit };
 
 type ApiErrorPayload = { detail?: string } | null;
 
 /**
- * Normalizes candidate token values by trimming whitespace and filtering non-string values.
+ * Returns a cookie value by name for the active browser runtime.
  */
-function normalizeBearerToken(candidate: unknown): string | undefined {
-  if (typeof candidate !== 'string') {
+function getCookieValue(name: string): string | undefined {
+  if (typeof document === "undefined") {
     return undefined;
   }
-  const normalized = candidate.trim();
-  return normalized ? normalized : undefined;
+  const rawCookie = document.cookie ?? "";
+  return rawCookie
+    .split(";")
+    .map((entry) => entry.trim())
+    .find((entry) => entry.startsWith(`${name}=`))
+    ?.slice(name.length + 1);
 }
 
 /**
- * Resolves bearer token persisted for current browser session.
+ * Resolves the runtime CSRF token from browser cookie storage for API requests.
  */
-export function getRuntimeApiToken(): string | undefined {
-  if (typeof globalThis.sessionStorage === 'undefined') {
-    return undefined;
-  }
-  try {
-    return normalizeBearerToken(globalThis.sessionStorage.getItem(API_TOKEN_RUNTIME_STORAGE_KEY));
-  } catch {
-    return undefined;
-  }
+function resolveCsrfToken(): string | undefined {
+  return getCookieValue(CSRF_COOKIE_NAME);
 }
 
 /**
- * Resolves bearer token from authenticated browser-session storage.
+ * Returns whether a method should include CSRF metadata.
  */
-function resolveApiToken(): string | undefined {
-  return getRuntimeApiToken();
+function requiresCsrfHeader(method: string): boolean {
+  const normalizedMethod = method.toUpperCase();
+  return !CSRF_SAFE_METHODS.has(normalizedMethod);
 }
 
 /**
- * Stores or clears the per-user runtime API token in session storage.
- *
- * @param token Token value to persist for this browser session; clears persisted token when empty.
+ * Merges request headers and appends CSRF metadata for state-changing requests.
  */
-export function setRuntimeApiToken(token: string | null | undefined): void {
-  if (typeof globalThis.sessionStorage === 'undefined') {
-    return;
-  }
-  try {
-    const normalized = normalizeBearerToken(token);
-    if (normalized) {
-      globalThis.sessionStorage.setItem(API_TOKEN_RUNTIME_STORAGE_KEY, normalized);
-      return;
-    }
-    globalThis.sessionStorage.removeItem(API_TOKEN_RUNTIME_STORAGE_KEY);
-  } catch {
-    return;
-  }
-}
-
-/**
- * Merges request headers and appends bearer authorization when a token can be resolved.
- */
-function buildRequestHeaders(headers?: HeadersInit): Headers | undefined {
-  const apiToken = resolveApiToken();
-  if (!apiToken && !headers) {
-    return undefined;
-  }
-
+function buildRequestHeaders(method: string, headers?: HeadersInit): Headers | undefined {
   const requestHeaders = new Headers(headers);
-  if (apiToken) {
-    requestHeaders.set('Authorization', `Bearer ${apiToken}`);
+  if (method && requiresCsrfHeader(method)) {
+    const csrfToken = resolveCsrfToken();
+    if (csrfToken) {
+      requestHeaders.set(CSRF_HEADER_NAME, csrfToken);
+    }
   }
   return requestHeaders;
 }
 
 /**
- * Executes an API request with centralized auth-header handling.
+ * Executes an API request with shared fetch options and CSRF handling.
  */
 function apiRequest(input: string, init: ApiRequestInit = {}): Promise<Response> {
-  const headers = buildRequestHeaders(init.headers);
+  const method = init.method ?? "GET";
+  const headers = buildRequestHeaders(method, init.headers);
   return fetch(input, {
     ...init,
+    credentials: 'include',
     ...(headers ? { headers } : {}),
   });
 }
@@ -183,11 +162,12 @@ export function downloadBlobFile(blob: Blob, filename: string): void {
 }
 
 /**
- * Authenticates one user and returns issued bearer token plus role-bound session metadata.
+ * Authenticates one user and returns authenticated session metadata.
  */
 export async function loginWithPassword(username: string, password: string): Promise<AuthLoginResponse> {
   const response = await fetch(`${API_BASE}/auth/login`, {
     method: 'POST',
+    credentials: 'include',
     headers: { 'Content-Type': 'application/json' },
     body: JSON.stringify({
       username: username.trim(),
@@ -220,7 +200,7 @@ export async function getCurrentAuthSession(): Promise<AuthSessionInfo> {
 }
 
 /**
- * Revokes the current authenticated bearer session.
+ * Revokes the current authenticated session.
  */
 export async function logoutCurrentSession(): Promise<void> {
   const response = await apiRequest(`${API_BASE}/auth/logout`, {

frontend/src/types.ts

@@ -76,11 +76,12 @@ export interface AuthSessionInfo {
 }
 
 /**
- * Represents login response payload with issued bearer token and session metadata.
+ * Represents login response payload with issued session metadata.
  */
 export interface AuthLoginResponse extends AuthSessionInfo {
-  access_token: string;
+  access_token?: string;
   token_type: 'bearer';
+  csrf_token?: string;
 }
 
 /**