- read_transitions: catch sqlite3.Error (not just OperationalError) so a corrupt
ledger degrades to empty rather than raising into callers
- recorder open-row lookup: order by the monotonic transition_id (drop the
timestamp-format dependency)
- TransitionRecorder.close(): release the retained in-memory test connection
- dashboard task_detail: return only the exception TYPE, never str(exc) (a SQLite
message can carry the DB path)
- _instrument: coerce a status enum to .value defensively before the terminal check
- schema.migrate: document the ordering constraint for future ALTERs vs the
unconditional idempotent tail
Add a v3 task_transitions table (additive migration + startup assertion) and a
fail-soft, idempotent TransitionRecorder. build_graph gains an injected
transition_recorder that wraps every node via a functools.wraps'd _instrument
(signature-preserving so LangGraph still injects RunnableConfig); the coordinator
wires it. Records one row per node entry (idempotent under resume replay) and
closes the open row on terminal status. Backs the dashboard task-history view.
