The build GitHub Actions job failed during docs generation because importing eegnb.devices.eeg required muselsl (and effectively pylsl) at module import time, even in environments that do not use streaming backends.

• Root cause

  • eegnb/devices/eeg.py performed unconditional top-level imports of optional streaming dependencies.
  • Docs build path imports EEG modules, triggering ModuleNotFoundError before any streaming feature is invoked.

• What changed

  • Replaced hard imports of muselsl with guarded try/except imports.
  • Replaced hard imports of pylsl with guarded try/except imports.
  • On missing deps, wire symbols to missing_module(...)-backed wrappers so failures are deferred to actual streaming usage instead of package import.

• Behavioral impact

  • Non-streaming contexts (including docs build) can import EEG modules without requiring streaming extras.
  • Streaming code paths still fail fast with explicit runtime guidance when optional deps are not installed.

try:
    from muselsl import stream, list_muses, record, constants as mlsl_cnsts
except (ImportError, OSError):
    muselsl = missing_module("muselsl", "...", "streaming")
    def stream(*args, **kwargs): return muselsl.stream(*args, **kwargs)