feat(joinir): Phase 46 - P2-Mid canonical Normalized promotion

Promote P2-Mid patterns (_atoi real, _parse_number real) to canonical
Normalized→MIR(direct) route, completing P2 line transition.

Canonical set expansion (Phase 41 → Phase 46):
- P2-Core: Pattern2Mini, skip_ws mini/real, atoi mini
- P2-Mid: atoi real, parse_number real (NEW)

All JsonParser P2 loops (_skip_whitespace, _atoi, _parse_number) now
canonical Normalized - Structured→MIR is legacy/comparison-only.

Key changes:
- shape_guard.rs: Expanded is_canonical_shape() (+2 patterns)
  - JsonparserAtoiReal
  - JsonparserParseNumberReal
  - Made NormalizedDevShape enum public
- bridge.rs: Updated canonical routing comments (Phase 41 → 46)
- normalized.rs: Made shape_guard module public
- normalized_joinir_min.rs: Added Phase 46 canonical verification test
- phase46-norm-canon-p2-mid.md: Complete design documentation

Out of scope (deferred):
- P3/P4 Normalized support → NORM-P3/NORM-P4 phases
- Selfhost complex loops → separate phases

Benefits:
- Clear P2 boundary: All JsonParser P2 = Normalized canonical
- Infrastructure validation: Phase 43/245B proven production-ready
- Simplified mental model: P2 = Normalized-first, P3/P4 = future

Tests: 937/937 PASS (lib), 20/20 PASS (normalized_dev feature)
Phase 46 test: test_phase46_canonical_set_includes_p2_mid ✅

docs/development/current/main/phase46-norm-canon-p2-mid.md

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+# Phase 46: Normalized Canonical P2-Mid Promotion
+
+**Status**: Implemented ✅ (2025-12-12)
+**Test Coverage**: 937/937 PASS
+
+## Goal
+
+Promote P2-Mid patterns (_atoi real, _parse_number real) to canonical Normalized→MIR(direct) route, alongside existing P2-Core patterns.
+
+## Scope
+
+**In Scope (P2 patterns)**:
+- JsonparserAtoiReal → canonical Normalized
+- JsonparserParseNumberReal → canonical Normalized
+
+**Out of Scope (deferred to future phases)**:
+- Pattern3 (if-sum) → NORM-P3
+- Pattern4 (continue) → NORM-P4
+- Selfhost complex loops → separate phases
+
+## Rationale
+
+With Phase 43/245B infrastructure complete, JsonParser P2-Mid loops (_atoi, _parse_number) are production-ready for canonical Normalized route:
+
+1. **Proven infrastructure**: DigitPos dual-value, NumberAccumulation, StepSchedule all working
+2. **Real-world validation**: JsonParser _atoi/_parse_number tests passing (937/937)
+3. **Clear boundary**: P2 vs P3/P4 separation simplifies rollout
+
+After Phase 46, P2 line becomes "Normalized-first" - Structured→MIR is legacy/comparison only.
+
+## Implementation Checklist
+
+### 1. Expand Canonical Set (shape_guard.rs)
+
+✅ Update `is_canonical_shape()` to include:
+- JsonparserAtoiReal
+- JsonparserParseNumberReal
+
+✅ Update doc comments:
+- "Phase 41 canonical set" → "Phase 46 canonical set: P2-Core + P2-Mid"
+
+### 2. Verify Bridge Routing (bridge.rs)
+
+✅ Confirm `canonical_shapes()` routing unchanged (already calls `is_canonical_shape()`)
+
+✅ Update comments:
+- "Phase 41: P2-Core only" → "Phase 46: P2-Core + P2-Mid (_atoi/_parse_number real)"
+
+### 3. Add/Update Tests
+
+✅ Verify existing tests cover canonical routing:
+- `normalized_pattern2_jsonparser_atoi_real_vm_bridge_direct_matches_structured`
+- `normalized_pattern2_jsonparser_parse_number_real_vm_bridge_direct_matches_structured`
+
+✅ Add new unit test (normalized_dev feature only):
+- Verify canonical_shapes includes _atoi real / _parse_number real
+- Verify bridge always routes to Normalized→MIR(direct)
+
+### 4. Update Documentation
+
+✅ Add Phase 46 section to `joinir-architecture-overview.md`:
+- "JsonParser _skip_whitespace / _atoi / _parse_number now canonical Normalized"
+- Link to P3/P4 future work (NORM-P3/NORM-P4)
+
+✅ Add Phase 46 entry to `CURRENT_TASK.md`:
+- Scope: P2-Core/P2-Mid canonical (P3/P4 out of scope)
+- Done condition: shape_guard + bridge + tests + docs
+
+## Canonical Set Evolution
+
+| Phase | Canonical Patterns | Description |
+|-------|-------------------|-------------|
+| Phase 41 | P2-Core: Pattern2Mini, skip_ws mini/real, atoi mini | Initial canonical set |
+| **Phase 46** | **+ P2-Mid: atoi real, parse_number real** | **JsonParser production patterns** |
+| Future | P3/P4, Selfhost loops | Deferred to NORM-P3/NORM-P4 |
+
+## Testing Strategy
+
+**Existing coverage** (no new tests required):
+- `normalized_joinir_min.rs` already tests _atoi real / _parse_number real
+- VM output comparison verified (Normalized vs Structured)
+
+**New unit test** (shape + bridge integration):
+- Verify `canonical_shapes()` includes P2-Mid
+- Feature-gated: `#[cfg(feature = "normalized_dev")]`
+
+## Benefits
+
+1. **Clear P2 boundary**: All JsonParser P2 loops now Normalized-first
+2. **Simplified mental model**: P2 = Normalized canonical, P3/P4 = future work
+3. **Production-ready**: _atoi/_parse_number real validated through Phase 246-EX/247-EX
+
+## Next Steps (Out of Scope)
+
+- **NORM-P3**: Pattern3 (if-sum) Normalized support
+- **NORM-P4**: Pattern4 (continue) Normalized support
+- **Selfhost**: Complex loops from selfhost compiler
+
+## References
+
+- **Completion Summary**: [PHASE_43_245B_NORMALIZED_COMPLETION.md](./PHASE_43_245B_NORMALIZED_COMPLETION.md)
+- **Phase 44 Capabilities**: [phase44-shape-capabilities-design.md](./phase44-shape-capabilities-design.md)
+- **Phase 45 Mode**: [phase45-norm-mode-design.md](./phase45-norm-mode-design.md)