cli: add headless command-line layer (bal_* commands for the daemon, cmdline entry point, manifest 'cmdline' support, offline controller tests)

bal/cmdline.py

@@ -0,0 +1,69 @@
+"""
+bal.cmdline
+===========
+
+Compatibility shim for Electrum's plugin loader (command-line front-end).
+
+Electrum loads a plugin with ``gui_name='cmdline'`` by importing the
+``cmdline`` module of the plugin package and looking for a ``Plugin`` class.
+The real implementation lives in the ``bal.cli`` sub-package, so this module
+re-exports ``Plugin`` from ``bal.cli.plugin``.
+
+Like ``qt.py``, this file is not a one-line relative import because the very
+same code may be loaded as an *external* plugin from a ``.zip``, where Electrum
+imports the package under the synthetic top-level name
+``electrum_external_plugins.bal`` and never registers the intermediate parent
+packages.  See the module docstring of ``bal.qt`` for the full rationale.  The
+shim resolves the run-time package name, backfills the missing parents into
+``sys.modules`` and imports the real implementation via
+:func:`importlib.import_module`.
+
+Unlike ``qt.py``, this module MUST never import PyQt (the daemon loads it in a
+headless process).
+"""
+
+import importlib
+import sys
+
+
+def _ensure_parent_packages(pkg_name: str) -> None:
+    """Make sure every ancestor package of *pkg_name* is in ``sys.modules``.
+
+    When loaded from a zip as an external plugin, Electrum only executes the
+    plugin package ``__init__`` and the ``cmdline`` module.  The synthetic root
+    package (e.g. ``electrum_external_plugins``) and any intermediate packages
+    may be missing from ``sys.modules``, which breaks relative/absolute
+    sub-module imports.  We backfill them here using this module's own loader
+    so that ``importlib`` can find sibling sub-packages.
+    """
+    parts = pkg_name.split(".")
+    # Walk from the top-most ancestor down to (but not including) pkg_name.
+    for i in range(1, len(parts)):
+        ancestor = ".".join(parts[:i])
+        if ancestor in sys.modules:
+            continue
+        try:
+            importlib.import_module(ancestor)
+        except Exception:
+            # The synthetic root (e.g. 'electrum_external_plugins') often has no
+            # real spec.  Create a minimal namespace package stub so that the
+            # import machinery can still resolve its children.
+            import types
+
+            module = types.ModuleType(ancestor)
+            module.__path__ = []  # mark as a (namespace) package
+            sys.modules[ancestor] = module
+
+
+# The package this module belongs to. Could be 'electrum.plugins.bal' (internal)
+# or 'electrum_external_plugins.bal' (external zip), depending on how Electrum
+# loaded us.
+_PKG = __package__ or "bal"
+
+_ensure_parent_packages(_PKG)
+
+# Import the real implementation using the fully-qualified, run-time package
+# name so it works regardless of the synthetic prefix Electrum assigned.
+_plugin_module = importlib.import_module(_PKG + ".cli.plugin")
+
+Plugin = _plugin_module.Plugin  # noqa: F401  (re-exported for Electrum)