Add SqlCopilotRepository implementing the Repository Protocol's session
lifecycle (create_session/get_session) and compare_and_advance as a real
DB-level version-CAS: a single UPDATE ... WHERE version=base_version, with
rowcount==0 disambiguated into NotFoundError (missing session) vs
ConflictError (stale version). A UNIQUE(session_id, seq) collision on
conversation items during compare_and_advance is caught and mapped to
ConflictError, making the DB the seq authority. Remaining Repository
methods (checkpoints/runs/test-inputs/list_conversation) are stubbed with
NotImplementedError, deferred to Task 5.
Tested against SQLite in-memory: create/get round-trip, CAS version bump,
stale-version conflict leaving the row unchanged, missing-session
NotFoundError, and duplicate-seq ConflictError.
Implements WorkflowServiceDifyPort, the real DifyPort adapter that wires
the pure P1 domain and Task 1-3 helpers to WorkflowService,
AppGenerateService, and the node-execution repository. Each method opens
its own session, resolves account/app via the identity helpers, and
mutates the draft graph client-side (no server-side patch primitive)
before writing it back with graph_only=True/sync_agent_bindings=False.
Pins the publish workflow_id+commit gotcha and the hash-mismatch
re-mapping. Confirmed via mocked-service unit tests and a runtime_checkable
isinstance(..., DifyPort) check.
Charles Yao
