diff --git a/src/llvm_py/builders/block_lower.py b/src/llvm_py/builders/block_lower.py
index 15e6bab6..bec132bc 100644
--- a/src/llvm_py/builders/block_lower.py
+++ b/src/llvm_py/builders/block_lower.py
@@ -58,9 +58,9 @@ class DeferredTerminator(NamedTuple):
     vmap_snapshot: Dict[int, ir.Value]
 
 
-def resolve_jump_only_snapshots(builder, block_by_id: Dict[int, Dict[str, Any]], func_name: str = "unknown"):
+def resolve_jump_only_snapshots(builder, block_by_id: Dict[int, Dict[str, Any]], context):
     """Phase 131-14-B P0-2: Resolve jump-only block snapshots (Pass B).
-    Phase 132-P0: Use tuple-key (func_name, block_id) to prevent cross-function collision.
+    Phase 132-P1: Use context Box for function-local state isolation.
 
     This function runs AFTER all blocks have been lowered (Pass A) but BEFORE
     PHI finalization. It resolves snapshots for jump-only blocks by following
@@ -71,14 +71,14 @@ def resolve_jump_only_snapshots(builder, block_by_id: Dict[int, Dict[str, Any]],
     SSOT: Snapshots are based on CFG structure, not processing order.
 
     Args:
-        func_name: Function name for tuple-key (func_name, block_id) in block_end_values
+        context: FunctionLowerContext Box containing function-local state
     """
     import sys
 
     strict_mode = os.environ.get('NYASH_LLVM_STRICT') == '1'
     trace_vmap = os.environ.get('NYASH_LLVM_TRACE_VMAP') == '1'
 
-    jump_only = getattr(builder, '_jump_only_blocks', {})
+    jump_only = context.jump_only_blocks
     if not jump_only:
         if trace_vmap:
             print("[vmap/resolve/passB] No jump-only blocks to resolve", file=sys.stderr)
@@ -114,9 +114,9 @@ def resolve_jump_only_snapshots(builder, block_by_id: Dict[int, Dict[str, Any]],
             return resolved[bid]
 
         # Normal block - already has snapshot from Pass A
-        # Phase 132-P0: Use tuple-key (func_name, block_id)
-        if (func_name, bid) in builder.block_end_values:
-            snapshot = builder.block_end_values[(func_name, bid)]
+        # Phase 132-P1: Use context.block_end_values (simple block_id key)
+        snapshot = context.get_block_snapshot(bid)
+        if snapshot:
             if trace_vmap:
                 print(
                     f"[vmap/resolve/passB] bb{bid} is normal block with snapshot "
@@ -171,10 +171,10 @@ def resolve_jump_only_snapshots(builder, block_by_id: Dict[int, Dict[str, Any]],
         return {}
 
     # Resolve all jump-only blocks
-    # Phase 132-P0: Use tuple-key (func_name, block_id)
+    # Phase 132-P1: Use context.set_block_snapshot (simple block_id key)
     for bid in sorted(jump_only.keys()):
         snapshot = resolve(bid)
-        builder.block_end_values[(func_name, bid)] = snapshot
+        context.set_block_snapshot(bid, snapshot)
 
         if trace_vmap:
             print(
@@ -187,12 +187,12 @@ def resolve_jump_only_snapshots(builder, block_by_id: Dict[int, Dict[str, Any]],
         print(f"[vmap/resolve/passB] Pass B complete: resolved {len(jump_only)} jump-only blocks", file=sys.stderr)
 
 
-def lower_blocks(builder, func: ir.Function, block_by_id: Dict[int, Dict[str, Any]], order: List[int], loop_plan: Dict[str, Any] | None, func_name: str = "unknown"):
+def lower_blocks(builder, func: ir.Function, block_by_id: Dict[int, Dict[str, Any]], order: List[int], loop_plan: Dict[str, Any] | None, context):
     """Lower blocks in multi-pass to ensure PHIs are always before terminators.
 
     Phase 131-4: Multi-pass block lowering architecture
     Phase 131-14-B: Two-pass snapshot resolution
-    Phase 132-P0: Tuple-key (func_name, block_id) to prevent cross-function collision
+    Phase 132-P1: Use context Box for function-local state isolation
     - Pass A: Lower non-terminator instructions only (terminators deferred)
       - jump-only blocks: record metadata only, NO snapshot resolution
     - Pass B: PHI finalization happens in function_lower.py
@@ -203,7 +203,7 @@ def lower_blocks(builder, func: ir.Function, block_by_id: Dict[int, Dict[str, An
     other instructions, and terminators must be last.
 
     Args:
-        func_name: Function name for tuple-key (func_name, block_id) in block_end_values
+        context: FunctionLowerContext Box containing function-local state
     """
     skipped: set[int] = set()
     if loop_plan is not None:
@@ -329,10 +329,10 @@ def lower_blocks(builder, func: ir.Function, block_by_id: Dict[int, Dict[str, An
             else:
                 body_ops.append(inst)
         # Per-block SSA map
-        # Phase 132-Post: Use PhiManager Box for PHI filtering (Box-First principle)
+        # Phase 132-P1: Use context.phi_manager for PHI filtering (Box-First principle)
         vmap_cur: Dict[int, ir.Value] = {}
         try:
-            vmap_cur = builder.phi_manager.filter_vmap_preserve_phis(
+            vmap_cur = context.phi_manager.filter_vmap_preserve_phis(
                 builder.vmap or {},
                 int(bid)
             )
@@ -414,8 +414,9 @@ def lower_blocks(builder, func: ir.Function, block_by_id: Dict[int, Dict[str, An
                         created_ids.append(dst)
                         # P0-1.5: Update def_blocks IMMEDIATELY after instruction lowering
                         # This ensures resolver can detect defined_here for same-block uses
+                        # Phase 132-P1: Use context.add_def_block
                         try:
-                            builder.def_blocks.setdefault(dst, set()).add(block_data.get("id", 0))
+                            context.add_def_block(dst, block_data.get("id", 0))
                         except Exception:
                             pass
             except Exception:
@@ -434,12 +435,12 @@ def lower_blocks(builder, func: ir.Function, block_by_id: Dict[int, Dict[str, An
                 print(f"[vmap/id] Pass A bb{bid} snapshot id={id(vmap_snapshot)} keys={sorted(vmap_snapshot.keys())[:10]}", file=sys.stderr)
         # Phase 131-7: Sync ALL created values to global vmap (not just PHIs)
         # This ensures Pass C (deferred terminators) can access values from Pass A
-        # Phase 132-Post: Use PhiManager Box for PHI protection (Box-First principle)
+        # Phase 132-P1: Use context.phi_manager for PHI protection (Box-First principle)
         try:
             # Create sync dict from created values only
             sync_dict = {vid: vmap_cur[vid] for vid in created_ids if vid in vmap_cur}
             # PhiManager.sync_protect_phis ensures PHIs are never overwritten (SSOT)
-            builder.phi_manager.sync_protect_phis(builder.vmap, sync_dict)
+            context.phi_manager.sync_protect_phis(builder.vmap, sync_dict)
             if os.environ.get('NYASH_LLVM_VMAP_TRACE') == '1':
                 print(f"[vmap/sync] bb{bid} synced {len(sync_dict)} values to builder.vmap (PHIs protected)", file=sys.stderr)
         except Exception:
@@ -449,10 +450,6 @@ def lower_blocks(builder, func: ir.Function, block_by_id: Dict[int, Dict[str, An
         strict_mode = os.environ.get('NYASH_LLVM_STRICT') == '1'
         trace_vmap = os.environ.get('NYASH_LLVM_TRACE_VMAP') == '1'
 
-        # Initialize jump_only_blocks dict if not exists
-        if not hasattr(builder, '_jump_only_blocks'):
-            builder._jump_only_blocks = {}
-
         is_jump_only = is_jump_only_block(block_data)
         if trace_vmap:
             print(
@@ -483,7 +480,7 @@ def lower_blocks(builder, func: ir.Function, block_by_id: Dict[int, Dict[str, An
             elif len(preds_list) == 1:
                 # Single predecessor - record metadata for Pass B resolution
                 pred_bid = preds_list[0]
-                builder._jump_only_blocks[bid] = pred_bid
+                context.register_jump_only_block(bid, pred_bid)
 
                 # DO NOT create snapshot here - will be resolved in Pass B
                 # Set snap to None to indicate "skip storing in block_end_values"
@@ -516,7 +513,7 @@ def lower_blocks(builder, func: ir.Function, block_by_id: Dict[int, Dict[str, An
             snap = dict(vmap_cur)
 
         # Phase 131-14-B: Only store snapshot if not deferred (snap is not None)
-        # Phase 132-P0: Use tuple-key (func_name, block_id)
+        # Phase 132-P1: Use context.set_block_snapshot (simple block_id key)
         if snap is not None:
             try:
                 keys = sorted(list(snap.keys()))
@@ -525,8 +522,8 @@ def lower_blocks(builder, func: ir.Function, block_by_id: Dict[int, Dict[str, An
             trace_phi_json({"phi": "snapshot", "block": int(bid), "keys": [int(k) for k in keys[:20]]})
             for vid in created_ids:
                 if vid in vmap_cur:
-                    builder.def_blocks.setdefault(vid, set()).add(block_data.get("id", 0))
-            builder.block_end_values[(func_name, bid)] = snap
+                    context.add_def_block(vid, block_data.get("id", 0))
+            context.set_block_snapshot(bid, snap)
         else:
             # Jump-only block with deferred snapshot - don't store yet
             if trace_vmap:
diff --git a/src/llvm_py/builders/function_lower.py b/src/llvm_py/builders/function_lower.py
index 65e1aac1..16c33b3e 100644
--- a/src/llvm_py/builders/function_lower.py
+++ b/src/llvm_py/builders/function_lower.py
@@ -9,74 +9,8 @@ from phi_wiring import (
     finalize_phis as _finalize_phis,
     build_succs as _build_succs,
 )
-
-
-def _clear_function_local_state(builder):
-    """
-    Phase 132-P1: Clear all function-local state at function boundary.
-
-    Box-First Principle: Prevents cross-function ValueId/BlockId collisions
-    by clearing all function-scoped state when entering a new function.
-
-    Cleared state:
-    1. PhiManager.predeclared - (bid, vid) -> phi_value
-    2. Resolver caches - i64_cache, ptr_cache, f64_cache, _end_i64_cache
-    3. Jump-only blocks - _jump_only_blocks
-    4. PHI incomings - block_phi_incomings, def_blocks
-    5. String/NewBox caches - function-local string handling
-    """
-    try:
-        # 1. PhiManager predeclared PHIs (bid, vid) -> phi_value
-        if hasattr(builder, 'phi_manager') and hasattr(builder.phi_manager, 'predeclared'):
-            builder.phi_manager.predeclared.clear()
-    except Exception:
-        pass
-
-    try:
-        # 2. Resolver caches (all keyed by block/value IDs)
-        builder.resolver.i64_cache.clear()
-        builder.resolver.ptr_cache.clear()
-        builder.resolver.f64_cache.clear()
-        if hasattr(builder.resolver, '_end_i64_cache'):
-            builder.resolver._end_i64_cache.clear()
-
-        # 3. String-related caches (function-local)
-        if hasattr(builder.resolver, 'string_ids'):
-            builder.resolver.string_ids.clear()
-        if hasattr(builder.resolver, 'string_literals'):
-            builder.resolver.string_literals.clear()
-        if hasattr(builder.resolver, 'string_ptrs'):
-            builder.resolver.string_ptrs.clear()
-        if hasattr(builder.resolver, 'length_cache'):
-            builder.resolver.length_cache.clear()
-
-        # 4. NewBox→string-arg hints (function-local)
-        if hasattr(builder.resolver, 'newbox_string_args') and isinstance(builder.resolver.newbox_string_args, dict):
-            builder.resolver.newbox_string_args.clear()
-    except Exception:
-        pass
-
-    try:
-        # 5. Jump-only blocks (bid -> pred_bid)
-        if hasattr(builder, '_jump_only_blocks'):
-            builder._jump_only_blocks.clear()
-    except Exception:
-        pass
-
-    try:
-        # 6. PHI incomings and def_blocks (function-local)
-        if hasattr(builder, 'block_phi_incomings'):
-            builder.block_phi_incomings.clear()
-        if hasattr(builder, 'def_blocks'):
-            builder.def_blocks.clear()
-
-        # Also clear resolver's references to these
-        if hasattr(builder.resolver, 'block_phi_incomings'):
-            builder.resolver.block_phi_incomings = {}
-        if hasattr(builder.resolver, 'def_blocks'):
-            builder.resolver.def_blocks.clear()
-    except Exception:
-        pass
+from context import FunctionLowerContext
+from phi_manager import PhiManager
 
 
 def lower_function(builder, func_data: Dict[str, Any]):
@@ -117,8 +51,24 @@ def lower_function(builder, func_data: Dict[str, Any]):
         builder.bb_map.clear()
     except Exception:
         builder.bb_map = {}
-    # Phase 132-P1: Clear all function-local state (prevent cross-function collision)
-    _clear_function_local_state(builder)
+
+    # Phase 132-P1: Create function-local context Box
+    # This automatically isolates all function-scoped state
+    context = FunctionLowerContext(name)
+
+    # Initialize PHI manager within context
+    context.phi_manager = PhiManager()
+
+    # Connect builder attributes to context storage (for backward compatibility)
+    builder.phi_manager = context.phi_manager
+    builder.block_phi_incomings = context.block_phi_incomings
+    builder.def_blocks = context.def_blocks
+
+    # Bind resolver to context (redirects caches to context storage)
+    builder.resolver.bind_context(context)
+
+    # Store context in builder for access by sub-components
+    builder.context = context
 
     # Phase 131-15-P1: Load value_types metadata from JSON into resolver
     try:
@@ -248,8 +198,9 @@ def lower_function(builder, func_data: Dict[str, Any]):
         if os.environ.get('NYASH_LLVM_PREPASS_IFMERGE') == '1':
             plan = plan_ret_phi_predeclare(block_by_id)
             if plan:
-                if not hasattr(builder, 'block_phi_incomings') or builder.block_phi_incomings is None:
-                    builder.block_phi_incomings = {}
+                # Phase 132-P1: block_phi_incomings already points to context storage
+                # No need to reassign - just ensure it exists
+                pass
                 for bbid, ret_vid in plan.items():
                     try:
                         preds_raw = [p for p in builder.preds.get(bbid, []) if p != bbid]
@@ -297,8 +248,8 @@ def lower_function(builder, func_data: Dict[str, Any]):
                     except Exception:
                         pass
             return uses
-        if not hasattr(builder, 'block_phi_incomings') or builder.block_phi_incomings is None:
-            builder.block_phi_incomings = {}
+        # Phase 132-P1: block_phi_incomings already points to context storage
+        # No need to reassign - it's already initialized
         for bid, blk in block_by_id.items():
             try:
                 preds_raw = [p for p in local_preds.get(int(bid), []) if p != int(bid)]
@@ -339,14 +290,14 @@ def lower_function(builder, func_data: Dict[str, Any]):
         loop_plan = None
 
     # Phase 131-4 Pass A: Lower non-terminator instructions (terminators deferred)
-    # Phase 132-P0: Pass func.name for tuple-key (func_name, block_id)
+    # Phase 132-P1: Pass context Box for function-local state isolation
     from builders.block_lower import lower_blocks as _lower_blocks
-    _lower_blocks(builder, func, block_by_id, order, loop_plan, func_name=name)
+    _lower_blocks(builder, func, block_by_id, order, loop_plan, context)
 
     # Phase 131-14-B Pass B: Resolve jump-only block snapshots (BEFORE PHI finalization)
-    # Phase 132-P0: Pass func_name for tuple-key
+    # Phase 132-P1: Pass context Box for function-local state isolation
     from builders.block_lower import resolve_jump_only_snapshots as _resolve_jump_only_snapshots
-    _resolve_jump_only_snapshots(builder, block_by_id, func_name=name)
+    _resolve_jump_only_snapshots(builder, block_by_id, context)
 
     # Optional: capture lowering ctx for downstream helpers
     try:
@@ -370,8 +321,8 @@ def lower_function(builder, func_data: Dict[str, Any]):
         pass
 
     # Phase 131-4 Pass B (now Pass B2): Finalize PHIs (wires incoming edges)
-    # Phase 132-P0: Pass func_name for tuple-key resolution
-    _finalize_phis(builder, func_name=name)
+    # Phase 132-P1: Pass context Box for function-local state isolation
+    _finalize_phis(builder, context)
 
     # Phase 131-4 Pass C: Lower deferred terminators (after PHIs are placed)
     from builders.block_lower import lower_terminators as _lower_terminators
diff --git a/src/llvm_py/context/__init__.py b/src/llvm_py/context/__init__.py
new file mode 100644
index 00000000..4cda5028
--- /dev/null
+++ b/src/llvm_py/context/__init__.py
@@ -0,0 +1,9 @@
+"""
+Phase 132-P1: Function-local context module
+
+Box-First principle: Isolate function-level state to prevent cross-function collisions.
+"""
+
+from .function_lower_context import FunctionLowerContext
+
+__all__ = ['FunctionLowerContext']
diff --git a/src/llvm_py/context/function_lower_context.py b/src/llvm_py/context/function_lower_context.py
new file mode 100644
index 00000000..e2214ada
--- /dev/null
+++ b/src/llvm_py/context/function_lower_context.py
@@ -0,0 +1,148 @@
+"""
+Function-local state container for LLVM lowering.
+
+Phase 132-P1: Box-First isolation of function-level state.
+Prevents cross-function state leakage and collisions.
+"""
+
+from typing import Dict, Set, Any
+from llvmlite import ir
+
+
+class FunctionLowerContext:
+    """
+    Box containing all function-local lowering state.
+
+    Lifetime: Created at function entry, destroyed at function exit.
+    Scope: Single MIR function lowering.
+
+    Benefits:
+    - Automatic state isolation (no manual clearing needed)
+    - Clear ownership (context belongs to one function)
+    - Easy to test (create context, lower, verify)
+
+    Design Principle (Box-First):
+    All function-scoped state lives here. This Box is created fresh for each
+    function and automatically destroyed when the function lowering completes,
+    ensuring zero cross-function contamination.
+    """
+
+    def __init__(self, func_name: str):
+        """Initialize function-local context.
+
+        Args:
+            func_name: Name of the function being lowered (for debugging/tracing)
+        """
+        self.func_name = func_name
+
+        # Block snapshot state (was: builder.block_end_values with tuple-key)
+        # Maps: block_id -> {value_id -> ir.Value}
+        # SSOT: End-of-block value snapshots for PHI wiring
+        self.block_end_values: Dict[int, Dict[int, ir.Value]] = {}
+
+        # Definition tracking (was: builder.def_blocks)
+        # Maps: value_id -> set of block_ids where it's defined
+        # Used by resolver to determine if value is defined in current block
+        self.def_blocks: Dict[int, Set[int]] = {}
+
+        # Jump-only blocks (was: builder._jump_only_blocks)
+        # Maps: jump_only_block_id -> predecessor_block_id
+        # Used for snapshot resolution in Pass B
+        self.jump_only_blocks: Dict[int, int] = {}
+
+        # PHI management (was: builder.phi_manager)
+        # Will be set to PhiManager instance
+        self.phi_manager: Any = None  # Type: PhiManager (avoid circular import)
+
+        # Resolver caches (function-local)
+        # These caches are keyed by (block_name, value_id) and must be
+        # cleared between functions to prevent cross-function collisions
+        self.resolver_i64_cache: Dict = {}
+        self.resolver_ptr_cache: Dict = {}
+        self.resolver_f64_cache: Dict = {}
+        self.resolver_end_i64_cache: Dict = {}
+
+        # String-related caches (function-local)
+        self.resolver_string_ids: Set[int] = set()
+        self.resolver_string_literals: Dict[int, str] = {}
+        self.resolver_string_ptrs: Dict[int, ir.Value] = {}
+        self.resolver_length_cache: Dict[int, ir.Value] = {}
+
+        # NewBox→string-arg hints (function-local)
+        self.resolver_newbox_string_args: Dict = {}
+
+        # PHI incomings metadata (function-local)
+        # Maps: block_id -> {value_id -> [(pred_bid, val_vid), ...]}
+        self.block_phi_incomings: Dict[int, Dict[int, Any]] = {}
+
+    def get_block_snapshot(self, block_id: int) -> Dict[int, ir.Value]:
+        """Get end-of-block value snapshot for a block.
+
+        Args:
+            block_id: Block ID to get snapshot for
+
+        Returns:
+            Dictionary mapping value_id -> ir.Value (empty dict if not found)
+        """
+        return self.block_end_values.get(block_id, {})
+
+    def set_block_snapshot(self, block_id: int, snapshot: Dict[int, ir.Value]) -> None:
+        """Set end-of-block value snapshot for a block.
+
+        Args:
+            block_id: Block ID to set snapshot for
+            snapshot: Dictionary mapping value_id -> ir.Value
+        """
+        self.block_end_values[block_id] = snapshot
+
+    def register_jump_only_block(self, block_id: int, pred_id: int) -> None:
+        """Register a block as jump-only (trampoline block).
+
+        Args:
+            block_id: ID of jump-only block
+            pred_id: ID of predecessor block to copy snapshot from
+        """
+        self.jump_only_blocks[block_id] = pred_id
+
+    def is_jump_only(self, block_id: int) -> bool:
+        """Check if a block is registered as jump-only.
+
+        Args:
+            block_id: Block ID to check
+
+        Returns:
+            True if block is jump-only, False otherwise
+        """
+        return block_id in self.jump_only_blocks
+
+    def add_def_block(self, value_id: int, block_id: int) -> None:
+        """Record that a value is defined in a block.
+
+        Args:
+            value_id: Value ID
+            block_id: Block ID where value is defined
+        """
+        if value_id not in self.def_blocks:
+            self.def_blocks[value_id] = set()
+        self.def_blocks[value_id].add(block_id)
+
+    def is_defined_in_block(self, value_id: int, block_id: int) -> bool:
+        """Check if a value is defined in a specific block.
+
+        Args:
+            value_id: Value ID to check
+            block_id: Block ID to check
+
+        Returns:
+            True if value is defined in the block, False otherwise
+        """
+        return block_id in self.def_blocks.get(value_id, set())
+
+    def __repr__(self) -> str:
+        """String representation for debugging."""
+        return (
+            f"FunctionLowerContext(func_name={self.func_name!r}, "
+            f"blocks={len(self.block_end_values)}, "
+            f"jump_only={len(self.jump_only_blocks)}, "
+            f"defs={len(self.def_blocks)})"
+        )
diff --git a/src/llvm_py/llvm_builder.py b/src/llvm_py/llvm_builder.py
index acbcdbbb..e5b49917 100644
--- a/src/llvm_py/llvm_builder.py
+++ b/src/llvm_py/llvm_builder.py
@@ -112,8 +112,9 @@ class NyashLLVMBuilder:
         self.phi_deferrals: List[Tuple[int, int, List[Tuple[int, int]]]] = []
         # Predecessor map and per-block end snapshots
         self.preds: Dict[int, List[int]] = {}
-        # Phase 132-P0: Tuple-key (func_name, block_id) to prevent cross-function collision
-        self.block_end_values: Dict[Tuple[str, int], Dict[int, ir.Value]] = {}
+        # Phase 132-P1: Legacy storage (replaced by FunctionLowerContext Box per-function)
+        # These are now only used as fallback/backward compatibility
+        self.block_end_values: Dict[int, Dict[int, ir.Value]] = {}
         # Definition map: value_id -> set(block_id) where the value is defined
         # Used as a lightweight lifetime hint to avoid over-localization
         self.def_blocks: Dict[int, set] = {}
diff --git a/src/llvm_py/phi_wiring/tagging.py b/src/llvm_py/phi_wiring/tagging.py
index 288ef8df..237ce595 100644
--- a/src/llvm_py/phi_wiring/tagging.py
+++ b/src/llvm_py/phi_wiring/tagging.py
@@ -18,7 +18,11 @@ def setup_phi_placeholders(builder, blocks: List[Dict[str, Any]]):
     """
     try:
         produced_str = collect_produced_stringish(blocks)
-        builder.block_phi_incomings = analyze_incomings(blocks)
+        # Phase 132-P1: Update existing block_phi_incomings dict (points to context storage)
+        # Don't replace it with assignment, as that breaks the connection to context
+        analyzed = analyze_incomings(blocks)
+        builder.block_phi_incomings.clear()
+        builder.block_phi_incomings.update(analyzed)
         trace({"phi": "setup", "produced_str_keys": list(produced_str.keys())})
 
         # Phase 132: Create all PHI placeholders FIRST, before any other operations
diff --git a/src/llvm_py/phi_wiring/wiring.py b/src/llvm_py/phi_wiring/wiring.py
index 313ddc35..3d74372e 100644
--- a/src/llvm_py/phi_wiring/wiring.py
+++ b/src/llvm_py/phi_wiring/wiring.py
@@ -137,12 +137,12 @@ def nearest_pred_on_path(
     return None
 
 
-def wire_incomings(builder, block_id: int, dst_vid: int, incoming: List[Tuple[int, int]], func_name: str = "unknown"):
+def wire_incomings(builder, block_id: int, dst_vid: int, incoming: List[Tuple[int, int]], context=None):
     """Wire PHI incoming edges for (block_id, dst_vid) using declared (decl_b, v_src) pairs.
-    Phase 132-P0: Accept func_name for tuple-key (func_name, block_id) resolution.
+    Phase 132-P1: Use context Box for function-local state isolation.
 
     Args:
-        func_name: Function name for tuple-key (func_name, block_id) in block_end_values
+        context: FunctionLowerContext Box containing function-local state
     """
     bb = builder.bb_map.get(block_id)
     if bb is None:
@@ -150,9 +150,14 @@ def wire_incomings(builder, block_id: int, dst_vid: int, incoming: List[Tuple[in
     # Prefer an existing PHI already materialized in this block (e.g., by resolver)
     phi = None
     try:
-        snap = getattr(builder, 'block_end_values', {}) or {}
-        # Phase 132-P0: Use tuple-key (func_name, block_id)
-        cur = (snap.get((func_name, int(block_id)), {}) or {}).get(int(dst_vid))
+        # Phase 132-P1: Use context.get_block_snapshot (simple block_id key)
+        if context is not None:
+            snapshot = context.get_block_snapshot(int(block_id))
+            cur = snapshot.get(int(dst_vid))
+        else:
+            # Fallback for backward compatibility
+            snap = getattr(builder, 'block_end_values', {}) or {}
+            cur = snap.get(int(block_id), {}).get(int(dst_vid))
         if cur is not None and hasattr(cur, 'add_incoming'):
             # Ensure it belongs to the same block
             cur_bb_name = getattr(getattr(cur, 'basic_block', None), 'name', None)
@@ -216,8 +221,8 @@ def wire_incomings(builder, block_id: int, dst_vid: int, incoming: List[Tuple[in
             trace({"phi": "wire_replaced_src", "original": original_vs, "replaced": vs})
         try:
             # P0-4: Use resolve_incoming for PHI incoming values
-            # Phase 132-P0: Pass func_name for tuple-key resolution
-            val = builder.resolver.resolve_incoming(pred_match, vs, func_name=func_name)
+            # Phase 132-P1: Pass context for function-local state isolation
+            val = builder.resolver.resolve_incoming(pred_match, vs, context=context)
             trace({"phi": "wire_resolved", "vs": vs, "pred": pred_match, "val_type": type(val).__name__})
         except Exception as e:
             trace({"phi": "wire_resolve_fail", "vs": vs, "pred": pred_match, "error": str(e)})
@@ -246,21 +251,21 @@ def wire_incomings(builder, block_id: int, dst_vid: int, incoming: List[Tuple[in
     return wired
 
 
-def finalize_phis(builder, func_name: str = "unknown"):
+def finalize_phis(builder, context):
     """Finalize PHI nodes by wiring their incoming edges.
-    Phase 132-P0: Pass func_name for tuple-key (func_name, block_id) resolution.
+    Phase 132-P1: Use context Box for function-local state isolation.
 
     Args:
-        func_name: Function name for tuple-key (func_name, block_id) in block_end_values
+        context: FunctionLowerContext Box containing function-local state
     """
     total_blocks = 0
     total_dsts = 0
     total_wired = 0
-    for block_id, dst_map in (getattr(builder, "block_phi_incomings", {}) or {}).items():
+    for block_id, dst_map in (context.block_phi_incomings or {}).items():
         total_blocks += 1
         for dst_vid, incoming in (dst_map or {}).items():
             total_dsts += 1
-            wired = wire_incomings(builder, int(block_id), int(dst_vid), incoming, func_name=func_name)
+            wired = wire_incomings(builder, int(block_id), int(dst_vid), incoming, context=context)
             total_wired += int(wired or 0)
             trace({"phi": "finalize", "block": int(block_id), "dst": int(dst_vid), "wired": int(wired or 0)})
     trace({"phi": "finalize_summary", "blocks": int(total_blocks), "dsts": int(total_dsts), "incoming_wired": int(total_wired)})
diff --git a/src/llvm_py/resolver.py b/src/llvm_py/resolver.py
index 43a7f654..f1428ffc 100644
--- a/src/llvm_py/resolver.py
+++ b/src/llvm_py/resolver.py
@@ -35,8 +35,12 @@ class Resolver:
             except Exception:
                 self.global_vmap = None
                 self.global_bb_map = None
-        
+
+        # Phase 132-P1: Context reference (will be set by bind_context)
+        self.context = None
+
         # Caches: (block_name, value_id) -> llvm value
+        # Phase 132-P1: These are now managed via context, but kept for backward compatibility
         self.i64_cache: Dict[Tuple[str, int], ir.Value] = {}
         self.ptr_cache: Dict[Tuple[str, int], ir.Value] = {}
         self.f64_cache: Dict[Tuple[str, int], ir.Value] = {}
@@ -49,7 +53,7 @@ class Resolver:
         self.string_ids: set[int] = set()
         # Cache for repeated string length queries when immutably known
         self.length_cache: Dict[int, ir.Value] = {}
-        
+
         # Type shortcuts
         self.i64 = ir.IntType(64)
         self.i8p = ir.IntType(8).as_pointer()
@@ -58,14 +62,39 @@ class Resolver:
         self._end_i64_cache: Dict[Tuple[int, int], ir.Value] = {}
         # Lifetime hint: value_id -> set(block_id) where it's known to be defined
         # Populated by the builder when available.
+        # Phase 132-P1: Now managed via context, but kept for backward compatibility
         self.def_blocks = {}
         # Optional: block -> { dst_vid -> [(pred_bid, val_vid), ...] } for PHIs from MIR JSON
         self.block_phi_incomings = {}
         # P0-1: SSOT for end-of-block values (snapshots)
+        # Phase 132-P1: Now managed via context, but kept for backward compatibility
         self.block_end_values = {}
         # P0-3: Circular reference detection (hang prevention)
         self._visited: Set[Tuple[int, int]] = set()
 
+    def bind_context(self, context):
+        """Phase 132-P1: Bind resolver to function-local context Box.
+
+        This connects the resolver's caches to the context's function-local storage,
+        enabling automatic isolation between functions.
+
+        Args:
+            context: FunctionLowerContext instance
+        """
+        self.context = context
+        # Redirect to context-managed storage
+        self.i64_cache = context.resolver_i64_cache
+        self.ptr_cache = context.resolver_ptr_cache
+        self.f64_cache = context.resolver_f64_cache
+        self._end_i64_cache = context.resolver_end_i64_cache
+        self.string_ids = context.resolver_string_ids
+        self.string_literals = context.resolver_string_literals
+        self.string_ptrs = context.resolver_string_ptrs
+        self.length_cache = context.resolver_length_cache
+        self.def_blocks = context.def_blocks
+        self.block_phi_incomings = context.block_phi_incomings
+        # Note: block_end_values access goes through context methods
+
     def mark_string(self, value_id: int) -> None:
         try:
             self.string_ids.add(int(value_id))
@@ -124,9 +153,9 @@ class Resolver:
         # Non-STRICT: fallback to 0
         return ir.Constant(ir.IntType(64), 0)
 
-    def resolve_incoming(self, pred_block_id: int, value_id: int, func_name: str = "unknown") -> ir.Value:
+    def resolve_incoming(self, pred_block_id: int, value_id: int, context=None) -> ir.Value:
         """P0-2: PHI incoming resolution (snapshot-only reference)
-        Phase 132-P0: Use tuple-key (func_name, block_id) to prevent cross-function collision
+        Phase 132-P1: Use context Box for function-local state isolation
 
         Used for resolving PHI incoming values from predecessor blocks.
         Only looks at block_end_values snapshot, never vmap_cur.
@@ -134,19 +163,26 @@ class Resolver:
         Args:
             pred_block_id: Predecessor block ID
             value_id: Value ID to resolve from predecessor
-            func_name: Function name for tuple-key (func_name, block_id) in block_end_values
+            context: FunctionLowerContext Box (if None, uses self.context)
 
         Returns:
             LLVM IR value (i64)
         """
-        # Phase 132-P0: Use tuple-key (func_name, block_id)
-        snapshot = self.block_end_values.get((func_name, pred_block_id), {})
+        # Phase 132-P1: Use context.get_block_snapshot (simple block_id key)
+        ctx = context if context is not None else self.context
+        if ctx is not None:
+            snapshot = ctx.get_block_snapshot(pred_block_id)
+        else:
+            # Fallback for backward compatibility (legacy code path)
+            snapshot = self.block_end_values.get(pred_block_id, {})
+
         val = snapshot.get(value_id)
         if val is not None:
             return val
 
         # Fail-Fast: snapshot miss → structural bug
         if os.environ.get('NYASH_LLVM_STRICT') == '1':
+            func_name = ctx.func_name if ctx else "unknown"
             raise RuntimeError(
                 f"[LLVM_PY/STRICT] resolve_incoming: v{value_id} not in {func_name}:bb{pred_block_id} snapshot. "
                 f"Available: {sorted(snapshot.keys())}"