# 007 MK2 Audit Target: Metainterpreter
# Status: PARTIALLY IMPLEMENTED — verified 2026-03-29
# Auditor: Claude Opus 4.6 (code-verified)

## Must Have

| Category | Feature | Status | Evidence |
|---|---|---|---|
| Syntax | Single source of truth for interpreter semantics | PASS | `eval.rs` (2194 lines) is the reference evaluator |
| Architecture | Modular language backends | PASS | 31 backends via BackendRegistry |
| Context | Discourse-bound context (dynamic typing/closures/coroutines) | PARTIAL | Discourse tracked in evaluator + meta-level via DiscourseMetaHook. NO closures, NO coroutines |
| Diagnostics | Error reporting for meta-level execution | PASS | `MetaError` enum (7 variants): ReflectionError, NotARecord, MissingField, FieldTypeError, HarvardViolation, HookError, Unsupported |
| Execution | Direct and meta-circular interpretation | PASS | Full reify→intercept→reflect→eval loop. 4 modes: Direct, MetaCircular, Stepping, Replay. 40 passing tests |

**Must Have: 4.5/5 (90%)**

## Should Have

| Category | Feature | Status | Evidence |
|---|---|---|---|
| Interop | Cross-language meta-interop | PARTIAL | Reified AST is serializable RtValue (serde); can be transmitted to other backends |
| Selection | Dynamic semantic selection (@meta_dynamic) | NOT IMPL | — |
| Performance | JIT for hot paths | NOT IMPL | jit.rs exists but is detection/hint only |
| Tooling | Semantic-aware tooling | PARTIAL | MetaHook trait enables external tools (debuggers, supervisors) to intercept evaluation. LoggingHook, FilterHook built-in |

**Should Have: 1/4 (25%)**

## Could Have

| Category | Feature | Status | Evidence |
|---|---|---|---|
| Concurrency | Parallel evaluation | NOT IMPL | — |
| Codegen | Semantic-aware codegen | NOT IMPL | — |
| Runtime | Runtime semantic switching | NOT IMPL | — |

**Could Have: 0/3 (0%)**

## Aspirational

| Category | Feature | Status | Evidence |
|---|---|---|---|
| Inference | Automated inference | NOT IMPL | — |
| Verification | Formal proofs of meta-interpretation equivalence | NOT IMPL | Roundtrip tests verify reify→reflect identity but no formal proof |
| Consistency | Language-wide consistency checks | NOT IMPL | — |

**Aspirational: 0/3 (0%)**

## Summary

**TOTAL: 5.5/15 (37%) — up from 13% (2/15) on 2026-03-27**

### Key Implementation Details (2026-03-29)

**Reification (AST → RtValue):**
- Complete coverage: DataExpr (14 variants), ControlExpr (17 variants), ControlStmt (15 variants), TopLevelDecl (14 variants)
- Plus: Pattern, BranchArm, GivenClause, GivenItem, Handler, LocaleExpr, BinOp, PredOp
- All nodes become `RtValue::Record` with `__kind` discriminant — pure Data (Harvard-safe)

**Reflection (RtValue → AST):**
- Complete inverse of reification with structured error handling
- Returns `Result<_, MetaError>` for malformed records

**Meta-Circular Eval Loop:**
- Reifies each declaration to Data
- Fires MetaHook callbacks (before_step / after_step)
- Reflects back to AST and evaluates via base evaluator
- Records MetaStep with: reified AST, result value, trace snapshot, env snapshot

**Interception Hooks (MetaHook trait):**
- `MetaHookAction`: Continue, Skip, Pause, Abort
- Built-in: LoggingHook, FilterHook, DiscourseMetaHook
- Stepping mode supports breakpoints and resume

**Discourse-Aware Meta-Evaluation:**
- DiscourseMetaHook enters/exits discourse per step
- INVARIANT 7 preserved: discourse does not leak between steps

**Benchmarks:** 18 criterion benchmarks covering reify/reflect/roundtrip/meta-circular/stepping/replay/hooks

### What Still Needs Work

1. **Closures and coroutines** in the base evaluator (not a meta-interpreter issue per se)
2. **JIT compilation** for hot meta-paths (jit.rs is detection only)
3. **Dynamic semantic selection** at meta-level (@meta_dynamic)
4. **Parallel meta-evaluation** (speculative branch at meta-level)
5. **Formal proofs** of reify→reflect→eval equivalence with direct eval

## Ecosystem Integration
- Package Manager: OPSM
- IDE: PanLL + Visual Codium (ENSAID)
