v0.6.8a2

Added

• StealthDependencyError — typed exception for compiled-dependency failures
  New exception class in exceptions.py that inherits from both StealthException and
  ImportError, fitting naturally into both the package exception hierarchy and standard
  except ImportError handlers.
  Raised whenever a compiled optional dependency (wreq, curl_cffi) fails to load —
  typically because a required native DLL or shared library could not be found.

  The exception provides a platform-aware, actionable message at raise time:

  • Windows — instructs the user to install both x64 and x86 Visual C++ Redistributables
    (2015–2022) with direct download links.
  • Linux — suggests the appropriate apt-get / yum packages for missing system
    libraries (libssl, libcurl).

  StealthDependencyError is exported from the top-level package and added to __all__,
  making it catchable in user code alongside the other stealth exceptions.

Fixed

• engines/basic.py — ImportError: DLL load failed while importing wreq on fresh Windows
  The bare from wreq.blocking import Client and from wreq.proxy import Proxy module-level
  imports crashed immediately on machines without the Visual C++ Redistributable installed,
  surfacing as an opaque DLL load failed traceback deep inside Scrapy's middleware loader.
  Both imports are now wrapped in try/except ImportError and delegate to
  StealthDependencyError.check("wreq", exc) for a clear, actionable error message.

• engines/turbo.py — same DLL failure for curl_cffi on fresh Windows
  from curl_cffi import CurlHttpVersion and from curl_cffi.requests import Session suffer
  the same failure path as wreq when the VCRT is absent.
  Both imports are now guarded with StealthDependencyError.check("curl_cffi", exc).

• utils/profiles.py — wreq.emulation crash at import time propagated silently
  from wreq.emulation import Emulation, Profile was a module-level import, meaning the
  entire profiles module — and by extension every engine that imports it — failed to load
  on VCRT-missing machines, producing the same deep DLL load failed traceback.
  The import is now guarded with a _WREQ_AVAILABLE flag; Emulation and Profile fall
  back to None so the module loads cleanly. The private _require_wreq() helper raises
  StealthDependencyError at the point of actual use (inside _resolve_basic), not at
  import time, keeping the turbo and browser drivers unaffected on machines where
  wreq is broken but curl_cffi loads fine.