v2.18.8 — Ledger API: specs 215-218 (DiffEntry.rel_info, history filter, NodeNotFoundError, post_commit_properties)

v2.18.8 (2026-09-10)

Ledger API: specs 215-218 — four friction-report items

Full SpecKit pipeline (specify → clarify → plan → tasks → analyze → implement)
completed for all four specs. E2E integration tests on ivg-iris-enterprise gate
each phase. 14 new unit tests + 10 new integration tests.

Spec 215 — DiffEntry.rel_info + fingerprint docstring (doc + minor API)

• DiffEntry.rel_info property: returns {"s","p","o","graph"} dict for
  relationship diff entries (entity_id is an opaque stmt_id; actual tuple is in
  after/before JSON). Returns None for non-relationship entries.
• Changeset.fingerprint() now has a docstring stating exactly which fields are
  hashed (actor, actor_type, ops) and which are excluded (expected_head,
  idempotency_key, etc.).
• CommitResult class docstring notes replayed=True can occur with a different
  expected_head — fingerprint does not include it.
• USER_GUIDE §10: new Idempotency subsection; rel_info usage example in diff section.

Spec 216 — ledger.history() source filter (enhancement)

• history(correlation_id=..., source=...) — new filter params pushed to SQL.
• idx_ledger_correlation added to ensure_indexes() as an optional index.
• Multi-tenant example added to USER_GUIDE §10 History subsection.

Spec 217 — create_relationship missing-node (bug fix + enhancement)

• NodeNotFoundError(LedgerError) — new exception with .missing_node attribute;
  raised by commit() when a node is missing (parses "node_not_found: 'X'" from
  ObjectScript response).
• Changeset(auto_stub_missing_nodes=True) — create_relationship(s, p, o) auto-
  prepends upsert_node(s) and upsert_node(o) if not already in the changeset.
• NodeNotFoundError exported from iris_vector_graph.ledger.

Spec 218 — post_commit_properties (enhancement)

• Changeset.post_commit_properties: dict[str, dict[str, str]] — applied after
  successful commit via direct SQL (Approach A — no new revision created).
• REVISION_ID_SENTINEL = "$REVISION_ID" — placeholder substituted with the actual
  revision_id after commit, enabling audit trails without a second commit.
• CommitResult.post_commit_applied: bool and CommitResult.post_commit_error: Optional[str].
• USER_GUIDE §10: Post-commit properties section with audit trail example.