feat(bundles): metapackage split (Phase A) — engine-only lfx, lfx-bundles long tail, 5 graduated partner packages

BUNDLE_API.md

@@ -402,3 +402,20 @@ the deserialize half is covered by
   added to ``ERROR_CODES`` (additive; codes-as-contract semantics
   preserved).  In-tree polling clients that never sent the parameter
   are unaffected.
+- **Manifest-less `lfx.bundles` discovery (metapackage split, 1.11).**  A
+  distribution may declare `[project.entry-points."lfx.bundles"]` whose
+  value is an importable package; each immediate subdirectory is loaded as
+  one bundle at the `@official` slot with **no `extension.json`** (the
+  langchain-community model; exempt from `lfx extension validate`).
+  `load_lfx_bundles_extensions` is exported from `lfx.extension` (additive).
+  Discovery precedence for cross-source bundle-name collisions becomes
+  `installed > seed > lfx_bundles > dev > inline` -- **manifest always
+  wins**, so a manifest-shipping `lfx-<provider>` shadows the same-named
+  provider in a metapackage with the existing `bundle-shadowed` warning
+  (graduation requires no lockstep release).  New warning-only code
+  `bundle-discovery-malformed` added to `ERROR_CODES` (additive) for
+  unresolvable declarations and invalid provider directory names; it never
+  aborts startup.  Manifest-less bundles bypass the
+  `version-constraint-unsatisfied` API-version gate by construction (no
+  manifest to carry `lfx.compat`); install-time compatibility rides on the
+  metapackage's PEP 508 `lfx>=X,<Y` pin instead.

src/lfx/src/lfx/extension/__init__.py

@@ -79,6 +79,7 @@
         installed_extension_roots,
         load_extension,
         load_installed_extensions,
+        load_lfx_bundles_extensions,
         load_seed_extensions,
         manifest_owning_distributions,
     )
@@ -159,6 +160,7 @@
     "installed_extension_roots": "loader",
     "load_extension": "loader",
     "load_installed_extensions": "loader",
+    "load_lfx_bundles_extensions": "loader",
     "load_seed_extensions": "loader",
     "manifest_owning_distributions": "loader",
     # dev_registry
@@ -261,6 +263,7 @@ def __dir__() -> list[str]:
     "load_dev_extensions",
     "load_extension",
     "load_installed_extensions",
+    "load_lfx_bundles_extensions",
     "load_manifest",
     "load_migration_table",
     "load_seed_extensions",

src/lfx/src/lfx/extension/errors.py

@@ -86,6 +86,11 @@
         "seed-directory-not-found",
         "seed-bundle-shadowed",
         "bundle-shadowed",
+        # Manifest-less lfx.bundles root whose entry-point declaration could
+        # not be resolved to a real package directory. Surfaced as a *warning*
+        # (never aborts startup) so a broken third-party declaration degrades
+        # to "that bundle root is skipped".
+        "bundle-discovery-malformed",
         "duplicate-extension-id",
         # Reload-specific codes
         "reload-in-progress",
@@ -284,6 +289,9 @@ def __bool__(self) -> bool:  # pragma: no cover - convenience
         "Bundle {content!r} is registered from multiple discovery sources; the lower-precedence copy "
         "at {location} is being skipped in favor of the higher-precedence one."
     ),
+    "bundle-discovery-malformed": (
+        "lfx.bundles entry point {content!r} could not be resolved to a package directory: {message}"
+    ),
     "duplicate-extension-id": ("Extension id {content!r} is registered more than once (already at {location})."),
     "reload-in-progress": (
         "Reload already in progress for bundle {content!r}; refuse to start a second concurrent reload."

src/lfx/src/lfx/extension/loader/__init__.py

@@ -52,6 +52,10 @@
 follow-on touching one banner-section at a time.
 """
 
+from lfx.extension.loader._bundles_root import (
+    LFX_BUNDLES_ENTRY_POINT_GROUP,
+    load_lfx_bundles_extensions,
+)
 from lfx.extension.loader._discovery import DEFAULT_MODULE_NAMESPACE
 from lfx.extension.loader._orchestrator import (
     discover_inline_bundles,
@@ -78,6 +82,7 @@
 
 __all__ = [
     "DEFAULT_MODULE_NAMESPACE",
+    "LFX_BUNDLES_ENTRY_POINT_GROUP",
     "SLOT_EXTRA",
     "SLOT_OFFICIAL",
     "SLOT_VALUES",
@@ -90,6 +95,7 @@
     "load_extension",
     "load_inline_bundle",
     "load_installed_extensions",
+    "load_lfx_bundles_extensions",
     "load_seed_extensions",
     "manifest_owning_distributions",
 ]