fix(llvm_py): tag stringish across copy/phi for concat

src/llvm_py/instructions/binop.py

@@ -243,21 +243,29 @@ def lower_binop(
                     return val
                 return ir.Constant(i64, 0)
 
-            # Phase 196: TypeFacts SSOT - Use handle+handle only when BOTH are strings
-            lhs_tag = False; rhs_tag = False
+            # Phase 196: TypeFacts/Resolver SSOT - Use handle+handle only when BOTH are strings.
+            # Root cause (Phase 102): loop-carried string accumulator may be i64-handle but not present in value_types;
+            # tag lookup MUST consult resolver.is_stringish()/string_ids.
+            lhs_tag = False
+            rhs_tag = False
             try:
                 if resolver is not None:
-                    # Check string_literals (actual string constants)
+                    # SSOT: resolver's stringish tag (propagated via Copy/PHI)
+                    if hasattr(resolver, 'is_stringish'):
+                        lhs_tag = bool(resolver.is_stringish(lhs))
+                        rhs_tag = bool(resolver.is_stringish(rhs))
+                    # Legacy: actual string constants by ValueId
                     if hasattr(resolver, 'string_literals'):
-                        lhs_tag = lhs in resolver.string_literals
-                        rhs_tag = rhs in resolver.string_literals
-                    # Check value_types for String/StringBox types
-                    if not lhs_tag and hasattr(resolver, 'value_types'):
+                        lhs_tag = lhs_tag or (lhs in resolver.string_literals)
+                        rhs_tag = rhs_tag or (rhs in resolver.string_literals)
+                    # Legacy: value_types hints (best-effort)
+                    if hasattr(resolver, 'value_types'):
+                        if not lhs_tag:
                             lhs_ty = resolver.value_types.get(lhs)
                             if lhs_ty and (lhs_ty.get('kind') == 'string' or
                                           (lhs_ty.get('kind') == 'handle' and lhs_ty.get('box_type') == 'StringBox')):
                                 lhs_tag = True
-                    if not rhs_tag and hasattr(resolver, 'value_types'):
+                        if not rhs_tag:
                             rhs_ty = resolver.value_types.get(rhs)
                             if rhs_ty and (rhs_ty.get('kind') == 'string' or
                                           (rhs_ty.get('kind') == 'handle' and rhs_ty.get('box_type') == 'StringBox')):

src/llvm_py/phi_wiring/analysis.py

@@ -5,7 +5,20 @@ from .common import trace
 
 
 def collect_produced_stringish(blocks: List[Dict[str, Any]]) -> Dict[int, bool]:
+    """Collect value-ids that are known to be string handles (best-effort).
+
+    This is used for early tagging (PHI placeholder setup) before instructions
+    are lowered/executed. Keep it monotonic and conservative.
+
+    Phase 102 root-cause:
+    - A string accumulator often goes through `copy` then `phi` before it's used
+      in `binop '+'`. If we don't propagate stringish across copy/phi here, the
+      PHI dst won't be tagged early, and the concat lowerer may incorrectly box
+      an i64-handle as an IntegerBox (breaking runtime string length/parity).
+    """
     produced_str: Dict[int, bool] = {}
+
+    # Seed: explicit producers with reliable type signals.
     for block_data in blocks:
         for inst in block_data.get("instructions", []) or []:
             try:
@@ -35,6 +48,57 @@ def collect_produced_stringish(blocks: List[Dict[str, Any]]) -> Dict[int, bool]:
                     produced_str[int(dstx)] = True
             except Exception:
                 pass
+
+    # Propagate: copy/phi/binop('+') can carry/produce stringish values even when
+    # dst_type metadata is missing. Use a small fixpoint iteration to cover chains.
+    changed = True
+    while changed:
+        changed = False
+        for block_data in blocks:
+            for inst in block_data.get("instructions", []) or []:
+                try:
+                    opx = inst.get("op")
+                    dstx = inst.get("dst")
+                    if dstx is None:
+                        continue
+                    dst_i = int(dstx)
+                    if produced_str.get(dst_i):
+                        continue
+
+                    if opx == "copy":
+                        src = inst.get("src")
+                        if src is not None and produced_str.get(int(src)):
+                            produced_str[dst_i] = True
+                            changed = True
+                            continue
+
+                    if opx == "phi":
+                        incoming0 = inst.get("incoming", []) or []
+                        # JSON v0 incoming pairs are (value_id, block_id)
+                        for (v_src, _b) in incoming0:
+                            try:
+                                if produced_str.get(int(v_src)):
+                                    produced_str[dst_i] = True
+                                    changed = True
+                                    break
+                            except Exception:
+                                continue
+                        continue
+
+                    if opx == "binop" and inst.get("operation") == "+":
+                        lhs = inst.get("lhs")
+                        rhs = inst.get("rhs")
+                        if lhs is not None and produced_str.get(int(lhs)):
+                            produced_str[dst_i] = True
+                            changed = True
+                            continue
+                        if rhs is not None and produced_str.get(int(rhs)):
+                            produced_str[dst_i] = True
+                            changed = True
+                            continue
+                except Exception:
+                    continue
+
     return produced_str
 
 
@@ -65,4 +129,3 @@ def analyze_incomings(blocks: List[Dict[str, Any]]) -> Dict[int, Dict[int, List[
                 except Exception:
                     pass
     return result
-