# Implementation Build Order
> **Historical document.** This describes the *scaffold build order* (Phases 1–13 below), not the release roadmap. For current milestone status, use [ROADMAP.md](../../ROADMAP.md) (Phases 0.1–0.10).
| 1–2 | 0.1 | Skeleton, COM |
| 3–4 | 0.1 | Parsing, diagnostics |
| 5–7 | 0.1–0.2 | Validation, types, interfaces |
| 8–10 | 0.3 | Compatibility, evolution, lineage |
| 11 | 0.7–0.9 | Plan, compile, runtime (now implemented) |
| 12–13 | 0.4–0.6 | Registry, stdlib, semantic analysis |
## Rule
Every implementation phase should consult `SPEC.md` first.
## Phase 1 — Project Skeleton
- Create Rust crate.
- Add dependencies.
- Add module structure.
- Add minimal README and examples.
## Phase 2 — Canonical Object Model
- Implement serializable structs.
- Use serde.
- Preserve identifiers and references.
- Avoid execution logic.
## Phase 3 — Parsing
- Load YAML.
- Load JSON.
- Convert into Canonical Object Model.
- Return structured diagnostics.
## Phase 4 — Diagnostics
- Implement diagnostic model.
- Severity, category, stage, message, object reference.
- Implement diagnostic report.
## Phase 5 — Validation
Implement validation phases from `SPEC.md`:
1. Document validation
2. Canonical Object Model validation
3. Structural validation
4. Type validation
5. Reference validation
6. Semantic validation
7. Extension validation
## Phase 6 — CLI
Commands:
```bash
dtcs validate contract.yaml
dtcs inspect contract.yaml
dtcs diagnostics contract.yaml
dtcs version
```
## Phase 7 — Contract Analysis (Phase 0.3)
- Compatibility comparison and five-level classification
- Evolution analysis with change categories
- Ch 25 versioning validation
- Dataset-level lineage analysis
Additional CLI commands:
```bash
dtcs compat source.yaml target.yaml
dtcs evolve older.yaml newer.yaml
dtcs lineage contract.yaml
```
## Phase 8 — Registries & Extensibility (Phase 0.4)
- Identifier registry model and embedded `dtcs:` catalog
- File/URI loading with offline cache
- Registry-aware semantic and extension validation
- `validate_with_registry` for vendor catalogs
Additional CLI commands:
```bash
dtcs registry list
dtcs registry resolve <id>
```
## Phase 9 — Standard Libraries (Phase 0.5)
- Embedded YAML catalogs under `src/registry/builtin/` for semantic actions, functions, and rules
- Structured JSON `definition` blocks on registry entries
- Registry-driven semantics validation in `src/validation/semantics.rs` (target types, phases, arity, return types)
- Starter catalog: string actions, common string/numeric functions, and constraint rules
Additional CLI commands (unchanged from Phase 8):
```bash
dtcs registry list
dtcs registry resolve <id>
```
## Phase 10 — Semantic Analysis (Phase 0.6)
- Static analysis of transformation semantics (Ch 7) and expression semantics (Ch 8)
- Expression AST parsing, type checking, constant folding, null semantics
- `analysis::check_contract` integrates with validation and plan lowering
Additional CLI command:
```bash
dtcs analyze <contract>
```
## Phase 11 — Transformation Plan (Phase 0.7)
- Canonical plan IR (`src/plan/model.rs`)
- Deterministic COM → plan lowering (`src/plan/lowering.rs`)
- Acyclic dependency graph (`src/plan/graph.rs`)
- Plan validation (`src/plan/validate.rs`)
- Golden plan fixtures under `tests/fixtures/plans/`
Additional CLI command:
```bash
dtcs plan <contract>
```
Phases 12–13 (optimization, capability matching, compilation, runtime) are implemented in ROADMAP 0.8–0.9. See [ROADMAP.md](../../ROADMAP.md).
## Phase 12 — Plan Optimization (Phase 0.8)
- Semantics-preserving plan optimization (`src/plan/optimize.rs`, `src/plan/equivalence.rs`)
- Expression constant folding and algebraic simplification
- Registry-gated deterministic function evaluation
- Action fusion and rule deduplication
- Golden optimized plan fixtures under `tests/fixtures/plans_optimized/`
Additional CLI command:
```bash
dtcs optimize <contract-or-plan>
```
## Phase 13 — Execution Pipeline (Phase 0.9)
- Engine capability model and embedded `dtcs:reference` profile
- Capability matching against transformation plans
- `ExecutionPlan` IR and reference compiler
- In-memory reference runtime for embedded `dtcs:` stdlib entries
- Golden runtime fixtures and end-to-end `customer_normalize` coverage
Additional CLI commands:
```bash
dtcs match <contract-or-plan>
dtcs compile <contract-or-plan>
dtcs run <contract> --input <json>
```