MazeNET phase 2 step 6. Equips the repo layer with the CRUD the web
editor needs before deploy.
- TopologyNotEditable exception: raised when a pending-only method hits
a non-pending topology. The intent is "free-form edits stop at deploy;
the mutator (step 7) takes over for live topologies."
- _assert_pending helper checks status inside the session.
- update_lan / update_topology_decky accept enforce_pending=True for
pre-deploy callers (existing internal callers default to False so
behavior is unchanged).
- delete_lan: cascades edges; refuses if any decky has only one edge
(= this LAN is its home) to prevent orphans.
- delete_topology_decky: cascades edges.
- delete_topology_edge: bare-bones removal.
All four mutators accept expected_version for optimistic concurrency.
Existing tests continue to pass (no behavior change for persist/deploy).
MazeNET phase 2 step 4. Readies the repo layer for concurrent editors
(web canvas + CLI + mutator) without lost-write races.
- Topology.version: monotonically bumped on supervised child-row writes.
- VersionConflict exception carries {current, expected} for the UI.
- _check_and_bump_version helper reads Topology in the same session,
compares against expected_version, raises on mismatch, bumps on match.
Commit happens in the caller's existing transaction so check+bump+write
are atomic per mutation.
- add_lan / update_lan / add_topology_decky / update_topology_decky /
add_topology_edge accept expected_version=None by default, preserving
every existing caller's behavior.
When expected_version is None, no check runs and version stays put —
internal callers (persist) that don't care about concurrency keep
working unchanged.
Adds decnet/topology/ with:
- config.TopologyConfig: pydantic model driving generation (depth,
branching_factor, deckies_per_lan_min/max, bridge_forward_probability,
cross_edge_probability, subnet_base_prefix, service selection, seed).
Emits GeneratedTopology dataclass (lans, deckies, edges).
- status.TopologyStatus + assert_transition: seven-state machine with
an explicit legal-transition table. torn_down is terminal; degraded
is schema-reserved for future Healer use.
- generator.generate: deterministic DAG generation under config.seed.
Builds a tree of LANs (DMZ at root), plants deckies in each LAN,
promotes one decky per non-DMZ LAN to a parent bridge, and rolls
cross-edges per cross_edge_probability for DAG shape.
- persistence: persist() writes a plan to the repo as pending;
transition_status() enforces state-machine legality; hydrate() loads
topology + children into a single dict.
Covered by tests/topology/{test_status,test_generator,test_persistence}.
