hakorune/docs/development/current/main/phase64-implementation-report.md

Phase 64 Implementation Report: Ownership P3 Production Integration

Executive Summary

Status: ✅ Complete Date: 2025-12-12 Feature Gate: normalized_dev Test Results: 49/49 tests passing, no regressions

Successfully integrated OwnershipPlan analysis into production P3 (if-sum) route with dev-only validation and Fail-Fast consistency checks.

Implementation Overview

Changes Made

1. Core API: analyze_loop() helper (ast_analyzer.rs)

Purpose: Analyze a single loop with parent context for P3 production integration.

pub fn analyze_loop(
    condition: &ASTNode,
    body: &[ASTNode],
    parent_defined: &[String],
) -> Result<OwnershipPlan, String>

Features:

• Creates temporary function scope for parent-defined variables
• Analyzes loop scope with condition (is_condition=true) and body
• Returns OwnershipPlan for loop scope only (not parent scope)
• Private helper build_plan_for_scope() for single-scope extraction

Key Design: Avoids analyzing entire function - only analyzes the specific loop being lowered.

2. P3 Production Integration (pattern3_with_if_phi.rs)

Location: Inside lower_pattern3_if_sum() method, after ConditionEnv building

Integration Point:

#[cfg(feature = "normalized_dev")]
{
    use crate::mir::join_ir::ownership::analyze_loop;

    // Collect parent-defined variables
    let parent_defined: Vec<String> = self.variable_map.keys()
        .filter(|name| *name != &loop_var_name)
        .cloned()
        .collect();

    // Analyze loop
    match analyze_loop(condition, body, &parent_defined) {
        Ok(plan) => {
            // Run consistency checks
            check_ownership_plan_consistency(&plan, &ctx.carrier_info, &condition_binding_names)?;
            // Continue with existing lowering (analysis-only)
        }
        Err(e) => {
            // Warn and continue (analysis is optional)
        }
    }
}

Key Design: Analysis happens after ConditionEnv but before JoinIR lowering, ensuring:

• All existing infrastructure is available for comparison
• No behavior change to lowering (analysis-only)
• Fail-Fast on critical errors only (multi-hop relay)

3. Consistency Checks (check_ownership_plan_consistency())

Check 1: Multi-hop relay rejection (Fail-Fast)

for relay in &plan.relay_writes {
    if relay.relay_path.len() > 1 {
        return Err(format!(
            "Phase 64 limitation: multi-hop relay not supported. Variable '{}' has relay path length {}",
            relay.name, relay.relay_path.len()
        ));
    }
}

Why Fail-Fast: Multi-hop relay requires semantic design beyond Phase 64 scope.

Check 2: Carrier set consistency (warn-only)

let plan_carriers: BTreeSet<String> = plan.owned_vars
    .iter()
    .filter(|v| v.is_written)
    .map(|v| v.name.clone())
    .collect();

let existing_carriers: BTreeSet<String> = carrier_info.carriers
    .iter()
    .map(|c| c.name.clone())
    .collect();

if plan_carriers != existing_carriers {
    eprintln!("[phase64/ownership] Carrier set mismatch (warn-only, order SSOT deferred):");
    eprintln!("  OwnershipPlan carriers: {:?}", plan_carriers);
    eprintln!("  Existing carriers: {:?}", existing_carriers);
}

Why warn-only: Carrier order SSOT is deferred to Phase 65+. This is a monitoring check only.

Check 3: Condition captures consistency (warn-only)

let plan_cond_captures: BTreeSet<String> = plan.condition_captures
    .iter()
    .map(|c| c.name.clone())
    .collect();

if !plan_cond_captures.is_subset(condition_bindings) {
    let extra: Vec<_> = plan_cond_captures
        .difference(condition_bindings)
        .collect();
    eprintln!("[phase64/ownership] Extra condition captures in plan (warn-only): {:?}", extra);
}

Why warn-only: Some patterns may legitimately have extra captures during development.

4. Regression Tests (normalized_joinir_min.rs)

Test 1: test_phase64_p3_ownership_prod_integration()

• Pattern: loop(i < 10) { local sum=0; local i=0; sum=sum+i; i=i+1; }
• Verifies:
  • Owned vars: sum (is_written=true), i (is_written=true, is_condition_only=true)
  • No relay writes (all loop-local)
  • Single-hop relay constraint

Test 2: test_phase64_p3_multihop_relay_detection()

• Pattern: Nested loops with function-scoped variable written in inner loop
• Verifies:
  • Multi-hop relay detection (relay_path.len() = 2)
  • Documents that rejection happens in consistency check (not analyze_loop)

Test Results

# Phase 64 specific tests
cargo test --features normalized_dev --test normalized_joinir_min test_phase64
# Result: 2/2 passed

# Ownership module tests
cargo test --features normalized_dev --lib ownership
# Result: 23/23 passed

# Full normalized_joinir_min suite
cargo test --features normalized_dev --test normalized_joinir_min
# Result: 49/49 passed (no regressions)

Design Decisions

Why analyze_loop() instead of full function analysis?

Decision: Create a loop-specific helper that analyzes only the loop scope.

Rationale:

• P3 production route only needs loop-level information
• Full function analysis would require threading through call stack
• Loop-specific API matches the existing P3 lowering architecture
• Simpler to test and verify correctness

Why dev-only (normalized_dev feature)?

Decision: Gate all new code with #[cfg(feature = "normalized_dev")].

Rationale:

• Analysis-only implementation (no behavior change)
• Early detection of inconsistencies without risk
• Allows iterative refinement before canonical promotion
• Easy to disable if issues are discovered

Why Fail-Fast only for multi-hop relay?

Decision: Only reject multi-hop relay (relay_path.len() > 1), warn for other mismatches.

Rationale:

• Multi-hop relay requires semantic design (Phase 65+)
• Carrier set mismatches might indicate existing edge cases (monitor first)
• Condition capture extras might be expected during development
• Fail-Fast only for truly blocking issues

Why integrate after ConditionEnv building?

Decision: Call analyze_loop() after ConditionEnv is built but before JoinIR lowering.

Rationale:

• ConditionEnv provides condition_bindings for comparison
• CarrierInfo is available from PatternPipelineContext
• ExitMeta will be available after lowering for future comparison
• No behavior change - analysis is non-invasive

Constraints and Limitations

Phase 64 Constraints

1. Single-hop relay only: relay_path.len() > 1 → Err
2. Analysis-only: No changes to lowering behavior
3. Dev-only: #[cfg(feature = "normalized_dev")] throughout
4. Warn-only mismatches: Carrier set and condition captures

Known Limitations

1. No carrier order SSOT: Existing CarrierInfo order is preserved
2. No owner-based init: Legacy FromHost initialization unchanged
3. No multi-hop relay support: Out of scope for Phase 64
4. Parent context simplification: Uses all variable_map keys except loop_var

Future Work (Phase 65+)

Phase 65: Carrier Order SSOT

Goal: Use OwnershipPlan to determine carrier order (upgrade warn to error).

Changes:

• Make OwnershipPlan the source of truth for carrier set
• Remove existing carrier inference logic
• Enforce carrier order consistency (fail on mismatch)

Phase 66: Owner-Based Initialization

Goal: Replace legacy FromHost with owner-based initialization.

Changes:

• Use OwnershipPlan to determine initialization strategy
• Implement proper initialization for relay writes
• Handle condition-only carriers correctly

Phase 67+: Multi-Hop Relay Support

Goal: Remove relay_path.len() > 1 limitation.

Semantic Design Needed:

• How to represent multi-hop relay in JoinIR
• PHI insertion strategy for intermediate loops
• Boundary input/output handling
• Exit line connection across multiple loops

References

• Phase 62: Ownership P3 Route Design
• Phase 63: AST Ownership Analyzer
• Phase 64 Summary: PHASE_64_SUMMARY.md
• JoinIR Architecture: joinir-architecture-overview.md

Conclusion

Phase 64 successfully connects OwnershipPlan analysis to production P3 route with:

• ✅ Dev-only validation (no behavior change)
• ✅ Fail-Fast for critical errors (multi-hop relay)
• ✅ Comprehensive consistency checks (carrier set, condition captures)
• ✅ Full test coverage (49/49 tests passing)
• ✅ Zero regressions

The implementation provides a solid foundation for Phase 65+ enhancements while maintaining existing functionality.