splitGraph 0.2.0

New features

• JSON serialization for both core handoff objects: write_dependency_graph() / read_dependency_graph() and write_split_spec() / read_split_spec(). The on-disk format is documented under ?write_dependency_graph and ?write_split_spec, carries a schema_version field, and round-trips NA values faithfully. This makes splitGraph objects portable across R sessions and across language boundaries (Python, Julia, CLI tools — anything that can read JSON). Requires jsonlite (added to Suggests); a helpful error is raised if it is not installed.
• A new vignette, adapter-cookbook, walks through three small adapter patterns: a base-R leave-one-group-out adapter (executed), a grouped-CV adapter built on rsample::group_vfold_cv() (illustrative), and an ordered-evaluation adapter built on rsample::rolling_origin() (illustrative). It also shows the JSON cross-language handoff path.
• validate_graph() and validate_depgraph() now accept a documented validation_overrides argument. Currently supported override: allow_multi_subject_samples (default FALSE); when TRUE, samples linked to multiple subjects are not flagged by the semantic validator and derive_split_constraints(mode = "subject") keeps the first listed assignment instead of erroring. The override mechanism is now first-class and merges into any graph-level override for the duration of the call only.
• derive_split_constraints(mode = "subject") honors allow_multi_subject_samples consistently with validate_graph(). When the override is active and ambiguity exists, the choice is recorded in metadata$warnings so it is not invisible.
• query_paths() now applies a finite default safety cap on max_length (8 edges) so that igraph::all_simple_paths() cannot blow up on dense graphs. Pass max_length = Inf to opt out and search exhaustively, or any non-negative integer for an explicit cap. Negative values and non-numeric inputs are rejected with a clear error.

Improvements

• build_dependency_graph() returns a more useful error when edge endpoints don’t match any node ID and the mismatch looks like a prefix problem (e.g. edges built with from_prefix = TRUE but nodes built with prefix = FALSE). The error now points at the likely cause.
• graph_from_metadata() warns when it constructs Outcome nodes from a numeric outcome_value column (which produces outcome:0 / outcome:1 nodes that are usually not what the user wants). To silence the warning, pass outcome_id (character class label) instead, or coerce outcome_value to character first.
• The data-model schema_version is now explicitly decoupled from the package version. Bumping the package will not bump the schema; only an explicit, documented schema change should.

Deprecations

These remain functional in 0.2.0 but emit .Deprecated() warnings and are scheduled for removal in a future release. Use the canonical names instead:

• validate_graph(checks = …) → use levels = … and severities = ….
• build_depgraph() → use build_dependency_graph().
• validate_depgraph() → use validate_graph().
• new_depgraph_nodes() → use graph_node_set().
• new_depgraph_edges() → use graph_edge_set().
• new_depgraph() → use dependency_graph().

Documentation

• README and the main vignette now use outcome_id (character) in their quick-start example instead of numeric outcome_value, matching the new warning behavior.
• The validation_overrides parameter and the allow_multi_subject_samples key are now documented on ?build_dependency_graph / ?validate_graph.

splitGraph 0.1.0

Initial public release. Highlights:

• Typed dependency-graph construction from canonical metadata via graph_from_metadata(), or from explicit node and edge tables via create_nodes() / create_edges() / build_dependency_graph().
• Structural, semantic, and leakage-relevant validation (validate_graph()), typed query helpers, and projected sample-dependency detection.
• Split-constraint derivation (derive_split_constraints()) for subject, batch, study, time, and composite modes, translated into a stable, tool-agnostic split_spec via as_split_spec() with preflight validation and leakage-risk summaries.
• plot() method for dependency_graph with a typed, layered layout, per-type node colors, and an auto-generated node-type legend.
• splitGraph emits split_spec objects without runtime dependencies on downstream tooling. Adapters are expected to live in consumer packages (e.g. packages built on top of rsample) so that splitGraph itself stays neutral.

See the README for a full feature overview and a runnable Quick Start.