# Repository structure

| Path | Role |
| --- | --- |
| `value.mbt` | Semantic `Value` enum, JSON conversion, `execute` boundary. |
| `input.mbt` | Request accessors, coercion helpers, the `input_error` code factory. |
| `expression.mbt` | Lexer, precedence parser, evaluator core with budgets and traces. |
| `static.mbt` | Opt-in schema-based checker mirroring runtime semantics. |
| `decision.mbt` | Rule loading, decide pipeline, operation dispatch, diff. |
| `format.mbt` | Canonical rendering, structural metrics, serialize/roundtrip. |
| `optimize.mbt` | Semantics-preserving rewrites; optimize operation and evaluate flag. |
| `aggregate.mbt` | Group-wise aggregation with semantic ordering. |
| `infer.mbt` | Schema inference over fact samples. |
| `analyze.mbt` | Static rule analysis: dependencies, tautologies, shadowing, ties. |
| `coverage.mbt` | Batch rule coverage tallies and pattern distribution. |
| `graph.mbt` | Fact-sharing dependency graph with union-find components. |
| `report.mbt` | Single-record text decision reports (explain). |
| `program.mbt` | Compile-once rule programs with tamper rejection. |
| `bundle.mbt` | Versioned policy bundles and migration resolution. |
| `quantify.mbt` | Array quantifiers: count_matches, any_match, all_match. |
| `extract.mbt` | Fact projection (pick) with missing-path accounting. |
| `ast.mbt` | Expression AST as JSON interchange. |
| `decision_table.mbt` | Business table compilation and one-call deciding. |
| `lint.mbt` | One-call governance gate composing analysis, types and bundle integrity. |
| `fmt.mbt` | Canonical rule-set formatting with change flags. |
| `schema_export.mbt` | JSON Schema draft 2020-12 export with inference fallback. |
| `migrate.mbt` | Bundle migration application to a run_program-ready artifact. |
| `validate.mbt` | Fact validation against engine schemas with required paths. |
| `conflicts.mbt` | Semantic condition relations: disjointness and subsumption. |
| `stats.mbt` | Engine self-description from compiled trees. |
| `waves.mbt` | Deployment wave scheduling from the dependency graph. |
| `regression.mbt` | Decision regression snapshots and compare diffs. |
| `template.mbt` | Parameterized rule-set rendering. |
| `score.mbt` | Condition complexity scoring with explicit reasons. |
| `explain_rules.mbt` | Plain-language sentence explanations. |
| `merge.mbt` | Rule-set merging with provenance and conflict strategies. |
| `matrix.mbt` | Decision-mode comparison matrix. |
| `audit.mbt` | Compliance-grade decision audit records. |
| `cmd/main/` | The JS host: file/stdin/.jsonl input, exit-code protocol. |
| `tests/cases.json` | The 77 CLI fixtures, mirrored as white-box tests. |
| `engine_wbtest.mbt` | 137 white-box tests over the public `run` boundary. |
| `scripts/` | Verification ladder, oracles, fuzzers, benchmarks; see docs/scripts.md. |
| `examples/` | Three scenario fixtures, the streaming pipeline, the browser demo. |
| `docs/` | Tutorial, API reference, errors, boundaries, design, benchmarks, structure. |

Module layering: everything above `decision.mbt` depends only on `expression.mbt` (trees and evaluation), `input.mbt` (accessors and codes), `format.mbt` (rendering/metrics) and `value.mbt` (values). `decision.mbt` is the only module that dispatches operations, so adding one is a new file plus a dispatch arm — no cross-module rewrites. Test code sits in `engine_wbtest.mbt` and drives the same `run` boundary as production callers.