M0 e M1 revisados e fixes implementados

RI/src/emcp_bus/registry/lifecycle.py

@@ -0,0 +1,44 @@
+"""Registry lifecycle state machine (EP-02-T04, README.md §23).
+
+    Nominate -> Review -> Register -> Publish -> Observe
+                                          Observe -> Change -> Publish
+                                          Observe -> Deprecate -> Retire
+
+`ACTIVE` collapses README.md's Publish+Observe into one steady state (a
+manifest that is live and being observed simultaneously, from this RI's
+point of view -- there is no separate "being observed" flag to track). The
+one invariant every caller of `transition()` gets for free is the one this
+task's acceptance criterion names directly: nothing reaches `ACTIVE` without
+having passed through `REVIEW` first.
+"""
+
+from __future__ import annotations
+
+from emcp_bus.registry.models import LifecycleStatus
+
+_ALLOWED_TRANSITIONS: dict[LifecycleStatus, frozenset[LifecycleStatus]] = {
+    LifecycleStatus.NOMINATE: frozenset({LifecycleStatus.REVIEW}),
+    # A rejected review goes back to NOMINATE (revise and resubmit) rather
+    # than staying stuck in REVIEW or disappearing from the registry.
+    LifecycleStatus.REVIEW: frozenset({LifecycleStatus.REGISTER, LifecycleStatus.NOMINATE}),
+    LifecycleStatus.REGISTER: frozenset({LifecycleStatus.ACTIVE}),
+    # "Change" (README.md §23) re-publishes an already-active capability;
+    # modeled as ACTIVE -> ACTIVE rather than a distinct state.
+    LifecycleStatus.ACTIVE: frozenset({LifecycleStatus.ACTIVE, LifecycleStatus.DEPRECATED}),
+    LifecycleStatus.DEPRECATED: frozenset({LifecycleStatus.RETIRED}),
+    LifecycleStatus.RETIRED: frozenset(),
+}
+
+
+class InvalidLifecycleTransitionError(Exception):
+    pass
+
+
+def validate_transition(current: LifecycleStatus, target: LifecycleStatus) -> None:
+    """Raises `InvalidLifecycleTransitionError` unless `current -> target` is
+    an allowed edge of the state machine above."""
+    if target not in _ALLOWED_TRANSITIONS.get(current, frozenset()):
+        raise InvalidLifecycleTransitionError(
+            f"{current.value} -> {target.value} is not an allowed registry "
+            f"lifecycle transition (README.md §23)"
+        )