diff --git a/src/backend/llvm/ops.zig b/src/backend/llvm/ops.zig
index b1c223ab..1c5fc7cf 100644
--- a/src/backend/llvm/ops.zig
+++ b/src/backend/llvm/ops.zig
@@ -1459,11 +1459,6 @@ pub const Ops = struct {
         }
     }
 
-    pub fn emitCompilerCall(self: Ops, instruction: *const Inst) void {
-        // Compiler hooks are comptime-only; if one reaches emission, produce undef
-        self.e.mapRef(c.LLVMGetUndef(self.e.toLLVMType(instruction.ty)));
-    }
-
     pub fn emitCallClosure(self: Ops, instruction: *const Inst, call_op: CallIndirect) void {
         // Closure: { fn_ptr, env }.
         //
diff --git a/src/ir/compiler_hooks.zig b/src/ir/compiler_hooks.zig
index 82f65d78..b8bba39b 100644
--- a/src/ir/compiler_hooks.zig
+++ b/src/ir/compiler_hooks.zig
@@ -1,13 +1,12 @@
 const std = @import("std");
 const Allocator = std.mem.Allocator;
-const interp_mod = @import("interp.zig");
-const Value = interp_mod.Value;
-const Interpreter = interp_mod.Interpreter;
 const inst = @import("inst.zig");
 const FuncId = inst.FuncId;
 
 // ── BuildConfig ─────────────────────────────────────────────────────────
-// Mutable build configuration accumulated by #run blocks via #compiler methods.
+// Mutable build configuration accumulated by the sx-driven build pipeline
+// (`default_pipeline` / an `on_build` callback) running on the comptime VM,
+// which reads/writes these fields via the `abi(.compiler)` primitives.
 
 /// `(src_dir, dest_in_bundle)` pair recorded by
 /// `BuildOptions.add_asset_dir(src, dest)`. The sx bundler walks the
@@ -144,440 +143,3 @@ pub const BuildHooks = struct {
     ) anyerror!void,
 };
 
-// ── Hook system ─────────────────────────────────────────────────────────
-
-pub const HookError = error{
-    CannotEvalComptime,
-    TypeError,
-};
-
-/// Hook function signature. Receives the interpreter (for heap/string access),
-/// resolved argument values, and the mutable build config.
-pub const HookFn = *const fn (
-    interp: *const Interpreter,
-    args: []const Value,
-    bc: *BuildConfig,
-    alloc: Allocator,
-) HookError!Value;
-
-pub const Registry = struct {
-    hooks: std.StringHashMap(HookFn),
-
-    pub fn init(alloc: Allocator) Registry {
-        return .{ .hooks = std.StringHashMap(HookFn).init(alloc) };
-    }
-
-    pub fn deinit(self: *Registry) void {
-        self.hooks.deinit();
-    }
-
-    pub fn get(self: *const Registry, name: []const u8) ?HookFn {
-        return self.hooks.get(name);
-    }
-
-    /// Register all built-in compiler hooks.
-    pub fn registerDefaults(self: *Registry) void {
-        self.hooks.put("build_options", &hookBuildOptions) catch {};
-        self.hooks.put("BuildOptions.add_link_flag", &hookAddLinkFlag) catch {};
-        self.hooks.put("BuildOptions.add_framework", &hookAddFramework) catch {};
-        self.hooks.put("BuildOptions.add_asset_dir", &hookAddAssetDir) catch {};
-        self.hooks.put("BuildOptions.asset_dir_count", &hookAssetDirCount) catch {};
-        self.hooks.put("BuildOptions.asset_dir_src_at", &hookAssetDirSrcAt) catch {};
-        self.hooks.put("BuildOptions.asset_dir_dest_at", &hookAssetDirDestAt) catch {};
-        self.hooks.put("BuildOptions.set_output_path", &hookSetOutputPath) catch {};
-        self.hooks.put("BuildOptions.set_wasm_shell", &hookSetWasmShell) catch {};
-        self.hooks.put("BuildOptions.set_post_link_callback", &hookSetPostLinkCallback) catch {};
-        self.hooks.put("BuildOptions.set_post_link_module", &hookSetPostLinkModule) catch {};
-        self.hooks.put("BuildOptions.binary_path", &hookGetBinaryPath) catch {};
-        // Bundling setters
-        self.hooks.put("BuildOptions.set_bundle_path", &hookSetBundlePath) catch {};
-        self.hooks.put("BuildOptions.set_bundle_id", &hookSetBundleId) catch {};
-        self.hooks.put("BuildOptions.set_codesign_identity", &hookSetCodesignIdentity) catch {};
-        self.hooks.put("BuildOptions.set_provisioning_profile", &hookSetProvisioningProfile) catch {};
-        // Bundling accessors
-        self.hooks.put("BuildOptions.bundle_path", &hookGetBundlePath) catch {};
-        self.hooks.put("BuildOptions.bundle_id", &hookGetBundleId) catch {};
-        self.hooks.put("BuildOptions.codesign_identity", &hookGetCodesignIdentity) catch {};
-        self.hooks.put("BuildOptions.provisioning_profile", &hookGetProvisioningProfile) catch {};
-        // Target accessors — mirror TargetConfig.is{MacOS,IOS,IOSDevice,IOSSimulator,Android}()
-        self.hooks.put("BuildOptions.target_triple", &hookGetTargetTriple) catch {};
-        self.hooks.put("BuildOptions.is_macos", &hookIsMacOS) catch {};
-        self.hooks.put("BuildOptions.is_ios", &hookIsIOS) catch {};
-        self.hooks.put("BuildOptions.is_ios_device", &hookIsIOSDevice) catch {};
-        self.hooks.put("BuildOptions.is_ios_simulator", &hookIsIOSSimulator) catch {};
-        self.hooks.put("BuildOptions.is_android", &hookIsAndroid) catch {};
-        // Android-specific setters + accessors
-        self.hooks.put("BuildOptions.set_manifest_path", &hookSetManifestPath) catch {};
-        self.hooks.put("BuildOptions.manifest_path", &hookGetManifestPath) catch {};
-        self.hooks.put("BuildOptions.set_keystore_path", &hookSetKeystorePath) catch {};
-        self.hooks.put("BuildOptions.keystore_path", &hookGetKeystorePath) catch {};
-        // #jni_main class emissions, exposed by index so bundle.sx can iterate.
-        self.hooks.put("BuildOptions.jni_main_count", &hookJniMainCount) catch {};
-        self.hooks.put("BuildOptions.jni_main_runtime_path_at", &hookJniMainRuntimePathAt) catch {};
-        self.hooks.put("BuildOptions.jni_main_java_source_at", &hookJniMainJavaSourceAt) catch {};
-        // Framework list accessors (for `.app/Frameworks/` embedding)
-        self.hooks.put("BuildOptions.framework_count", &hookFrameworkCount) catch {};
-        self.hooks.put("BuildOptions.framework_at", &hookFrameworkAt) catch {};
-        self.hooks.put("BuildOptions.framework_path_count", &hookFrameworkPathCount) catch {};
-        self.hooks.put("BuildOptions.framework_path_at", &hookFrameworkPathAt) catch {};
-    }
-};
-
-// ── build_options() hook ────────────────────────────────────────────────
-
-fn hookBuildOptions(
-    _: *const Interpreter,
-    _: []const Value,
-    _: *BuildConfig,
-    _: Allocator,
-) HookError!Value {
-    // build_options() returns a sentinel value; the real work happens
-    // when methods like add_link_flag/set_output_path are called on it.
-    return .void_val;
-}
-
-// ── BuildOptions hooks ──────────────────────────────────────────────────
-
-fn hookAddLinkFlag(
-    interp: *const Interpreter,
-    args: []const Value,
-    bc: *BuildConfig,
-    alloc: Allocator,
-) HookError!Value {
-    // args: [self (BuildOptions value), flag_string]
-    if (args.len < 2) return .void_val;
-    const str_val = args[1];
-    if (str_val.asString(interp)) |s| {
-        bc.link_flags.append(alloc, alloc.dupe(u8, s) catch return error.CannotEvalComptime) catch return error.CannotEvalComptime;
-    }
-    return .void_val;
-}
-
-fn hookAddFramework(
-    interp: *const Interpreter,
-    args: []const Value,
-    bc: *BuildConfig,
-    alloc: Allocator,
-) HookError!Value {
-    // args: [self (BuildOptions value), framework_name]
-    if (args.len < 2) return .void_val;
-    const str_val = args[1];
-    if (str_val.asString(interp)) |s| {
-        bc.frameworks.append(alloc, alloc.dupe(u8, s) catch return error.CannotEvalComptime) catch return error.CannotEvalComptime;
-    }
-    return .void_val;
-}
-
-fn hookAddAssetDir(
-    interp: *const Interpreter,
-    args: []const Value,
-    bc: *BuildConfig,
-    alloc: Allocator,
-) HookError!Value {
-    // args: [self (BuildOptions value), src_path, dest_path_in_bundle]
-    if (args.len < 3) return .void_val;
-    const src = args[1].asString(interp) orelse return error.TypeError;
-    const dest = args[2].asString(interp) orelse return error.TypeError;
-    const src_dup = alloc.dupe(u8, src) catch return error.CannotEvalComptime;
-    const dest_dup = alloc.dupe(u8, dest) catch return error.CannotEvalComptime;
-    bc.asset_dirs.append(alloc, .{ .src = src_dup, .dest = dest_dup }) catch return error.CannotEvalComptime;
-    return .void_val;
-}
-
-fn hookAssetDirCount(_: *const Interpreter, _: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    return Value{ .int = @intCast(bc.asset_dirs.items.len) };
-}
-
-fn hookAssetDirSrcAt(_: *const Interpreter, args: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    if (args.len < 2) return Value{ .string = "" };
-    const idx = args[1].asInt() orelse return error.TypeError;
-    if (idx < 0 or @as(usize, @intCast(idx)) >= bc.asset_dirs.items.len) return Value{ .string = "" };
-    return Value{ .string = bc.asset_dirs.items[@intCast(idx)].src };
-}
-
-fn hookAssetDirDestAt(_: *const Interpreter, args: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    if (args.len < 2) return Value{ .string = "" };
-    const idx = args[1].asInt() orelse return error.TypeError;
-    if (idx < 0 or @as(usize, @intCast(idx)) >= bc.asset_dirs.items.len) return Value{ .string = "" };
-    return Value{ .string = bc.asset_dirs.items[@intCast(idx)].dest };
-}
-
-fn hookSetOutputPath(
-    interp: *const Interpreter,
-    args: []const Value,
-    bc: *BuildConfig,
-    alloc: Allocator,
-) HookError!Value {
-    // args: [self (BuildOptions value), path_string]
-    if (args.len < 2) return .void_val;
-    const str_val = args[1];
-    if (str_val.asString(interp)) |s| {
-        bc.output_path = alloc.dupe(u8, s) catch return error.CannotEvalComptime;
-    }
-    return .void_val;
-}
-
-fn hookSetWasmShell(
-    interp: *const Interpreter,
-    args: []const Value,
-    bc: *BuildConfig,
-    alloc: Allocator,
-) HookError!Value {
-    // args: [self (BuildOptions value), path_string]
-    if (args.len < 2) return .void_val;
-    const str_val = args[1];
-    if (str_val.asString(interp)) |s| {
-        bc.wasm_shell_path = alloc.dupe(u8, s) catch return error.CannotEvalComptime;
-    }
-    return .void_val;
-}
-
-fn hookSetPostLinkCallback(
-    _: *const Interpreter,
-    args: []const Value,
-    bc: *BuildConfig,
-    _: Allocator,
-) HookError!Value {
-    // args: [self (BuildOptions value), fn_value]. We accept a function
-    // value (.func_ref) and stash the FuncId so `main.zig` can re-enter
-    // the interpreter after linking.
-    if (args.len < 2) return .void_val;
-    switch (args[1]) {
-        .func_ref => |id| bc.post_link_callback_fn = id,
-        else => return error.TypeError,
-    }
-    return .void_val;
-}
-
-fn hookSetPostLinkModule(
-    interp: *const Interpreter,
-    args: []const Value,
-    bc: *BuildConfig,
-    alloc: Allocator,
-) HookError!Value {
-    if (args.len < 2) return .void_val;
-    if (args[1].asString(interp)) |s| {
-        bc.post_link_module = alloc.dupe(u8, s) catch return error.CannotEvalComptime;
-    }
-    return .void_val;
-}
-
-/// Read the linked-binary path that main.zig populated right before
-/// invoking the post-link callback. Returns the fat-string aggregate
-/// the interpreter normally hands out for sx `string` values.
-fn hookGetBinaryPath(
-    interp: *const Interpreter,
-    _: []const Value,
-    bc: *BuildConfig,
-    _: Allocator,
-) HookError!Value {
-    _ = interp;
-    const path = bc.binary_path orelse "";
-    return Value{ .string = path };
-}
-
-// ── Bundling setters & accessors ─────────────────────────────────────
-// Same pattern as set_output_path: take a string arg, dupe into the
-// long-lived allocator, store on BuildConfig. The companion accessor
-// reads back the same field; empty string when unset.
-
-fn hookSetBundlePath(
-    interp: *const Interpreter,
-    args: []const Value,
-    bc: *BuildConfig,
-    alloc: Allocator,
-) HookError!Value {
-    if (args.len < 2) return .void_val;
-    if (args[1].asString(interp)) |s| {
-        bc.bundle_path = alloc.dupe(u8, s) catch return error.CannotEvalComptime;
-    }
-    return .void_val;
-}
-
-fn hookSetBundleId(
-    interp: *const Interpreter,
-    args: []const Value,
-    bc: *BuildConfig,
-    alloc: Allocator,
-) HookError!Value {
-    if (args.len < 2) return .void_val;
-    if (args[1].asString(interp)) |s| {
-        bc.bundle_id = alloc.dupe(u8, s) catch return error.CannotEvalComptime;
-    }
-    return .void_val;
-}
-
-fn hookSetCodesignIdentity(
-    interp: *const Interpreter,
-    args: []const Value,
-    bc: *BuildConfig,
-    alloc: Allocator,
-) HookError!Value {
-    if (args.len < 2) return .void_val;
-    if (args[1].asString(interp)) |s| {
-        bc.codesign_identity = alloc.dupe(u8, s) catch return error.CannotEvalComptime;
-    }
-    return .void_val;
-}
-
-fn hookSetProvisioningProfile(
-    interp: *const Interpreter,
-    args: []const Value,
-    bc: *BuildConfig,
-    alloc: Allocator,
-) HookError!Value {
-    if (args.len < 2) return .void_val;
-    if (args[1].asString(interp)) |s| {
-        bc.provisioning_profile = alloc.dupe(u8, s) catch return error.CannotEvalComptime;
-    }
-    return .void_val;
-}
-
-fn hookGetBundlePath(_: *const Interpreter, _: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    return Value{ .string = bc.bundle_path orelse "" };
-}
-
-fn hookGetBundleId(_: *const Interpreter, _: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    return Value{ .string = bc.bundle_id orelse "" };
-}
-
-fn hookGetCodesignIdentity(_: *const Interpreter, _: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    return Value{ .string = bc.codesign_identity orelse "" };
-}
-
-fn hookGetProvisioningProfile(_: *const Interpreter, _: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    return Value{ .string = bc.provisioning_profile orelse "" };
-}
-
-// ── Target accessors ──────────────────────────────────────────────────
-// These look at the target_triple that main.zig populates and answer
-// the same questions TargetConfig's helpers do for Zig callers.
-
-fn tripleContains(triple: ?[]const u8, needle: []const u8) bool {
-    const t = triple orelse return false;
-    return std.mem.indexOf(u8, t, needle) != null;
-}
-
-fn isIOSTriple(triple: ?[]const u8) bool {
-    return tripleContains(triple, "apple-ios");
-}
-
-fn hookGetTargetTriple(_: *const Interpreter, _: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    return Value{ .string = bc.target_triple orelse "" };
-}
-
-fn hookIsMacOS(_: *const Interpreter, _: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    if (isIOSTriple(bc.target_triple)) return Value{ .boolean = false };
-    const t = bc.target_triple orelse "";
-    const is_mac = std.mem.indexOf(u8, t, "apple-macosx") != null or
-        std.mem.indexOf(u8, t, "apple-macos") != null or
-        std.mem.indexOf(u8, t, "apple-darwin") != null;
-    return Value{ .boolean = is_mac };
-}
-
-fn hookIsIOS(_: *const Interpreter, _: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    return Value{ .boolean = isIOSTriple(bc.target_triple) };
-}
-
-fn hookIsIOSDevice(_: *const Interpreter, _: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    const ios = isIOSTriple(bc.target_triple);
-    const sim = tripleContains(bc.target_triple, "simulator");
-    return Value{ .boolean = ios and !sim };
-}
-
-fn hookIsIOSSimulator(_: *const Interpreter, _: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    const ios = isIOSTriple(bc.target_triple);
-    const sim = tripleContains(bc.target_triple, "simulator");
-    return Value{ .boolean = ios and sim };
-}
-
-fn hookIsAndroid(_: *const Interpreter, _: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    return Value{ .boolean = tripleContains(bc.target_triple, "android") };
-}
-
-// ── Android-specific bundling setters + accessors ─────────────────────
-
-fn hookSetManifestPath(interp: *const Interpreter, args: []const Value, bc: *BuildConfig, alloc: Allocator) HookError!Value {
-    if (args.len < 2) return .void_val;
-    if (args[1].asString(interp)) |s| {
-        bc.manifest_path = alloc.dupe(u8, s) catch return error.CannotEvalComptime;
-    }
-    return .void_val;
-}
-
-fn hookGetManifestPath(_: *const Interpreter, _: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    return Value{ .string = bc.manifest_path orelse "" };
-}
-
-fn hookSetKeystorePath(interp: *const Interpreter, args: []const Value, bc: *BuildConfig, alloc: Allocator) HookError!Value {
-    if (args.len < 2) return .void_val;
-    if (args[1].asString(interp)) |s| {
-        bc.keystore_path = alloc.dupe(u8, s) catch return error.CannotEvalComptime;
-    }
-    return .void_val;
-}
-
-fn hookGetKeystorePath(_: *const Interpreter, _: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    return Value{ .string = bc.keystore_path orelse "" };
-}
-
-// ── #jni_main emission accessors ──────────────────────────────────────
-// The Android bundler walks these as `0..jni_main_count()` and reads
-// each entry's `(runtime_path, java_source)` pair so it can write a
-// `.java` file per decl, compile via javac, and produce classes.dex
-// via d8 before zipping into the APK.
-
-fn hookJniMainCount(_: *const Interpreter, _: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    return Value{ .int = @intCast(bc.jni_main_runtime_paths.len) };
-}
-
-fn hookJniMainRuntimePathAt(_: *const Interpreter, args: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    if (args.len < 2) return Value{ .string = "" };
-    const idx = args[1].asInt() orelse return error.TypeError;
-    if (idx < 0 or @as(usize, @intCast(idx)) >= bc.jni_main_runtime_paths.len) return Value{ .string = "" };
-    return Value{ .string = bc.jni_main_runtime_paths[@intCast(idx)] };
-}
-
-fn hookJniMainJavaSourceAt(_: *const Interpreter, args: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    if (args.len < 2) return Value{ .string = "" };
-    const idx = args[1].asInt() orelse return error.TypeError;
-    if (idx < 0 or @as(usize, @intCast(idx)) >= bc.jni_main_java_sources.len) return Value{ .string = "" };
-    return Value{ .string = bc.jni_main_java_sources[@intCast(idx)] };
-}
-
-// ── Framework list accessors ──────────────────────────────────────────
-// The Apple .app bundler in `library/modules/platform/bundle.sx` walks
-// the framework list to recursively copy each `<Name>.framework`
-// directory from the user's -F search paths into `<bundle>/Frameworks/`.
-// Slice-of-string returns aren't natively expressible as a Value, so we
-// expose count + indexed lookups instead.
-
-fn intValue(n: i64) Value {
-    return Value{ .int = n };
-}
-
-fn hookFrameworkCount(_: *const Interpreter, _: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    return intValue(@intCast(bc.target_frameworks.len));
-}
-
-fn hookFrameworkAt(_: *const Interpreter, args: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    if (args.len < 2) return Value{ .string = "" };
-    const idx_i64 = args[1].asInt() orelse return error.TypeError;
-    if (idx_i64 < 0 or @as(usize, @intCast(idx_i64)) >= bc.target_frameworks.len) {
-        return Value{ .string = "" };
-    }
-    return Value{ .string = bc.target_frameworks[@intCast(idx_i64)] };
-}
-
-fn hookFrameworkPathCount(_: *const Interpreter, _: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    return intValue(@intCast(bc.target_framework_paths.len));
-}
-
-fn hookFrameworkPathAt(_: *const Interpreter, args: []const Value, bc: *BuildConfig, _: Allocator) HookError!Value {
-    if (args.len < 2) return Value{ .string = "" };
-    const idx_i64 = args[1].asInt() orelse return error.TypeError;
-    if (idx_i64 < 0 or @as(usize, @intCast(idx_i64)) >= bc.target_framework_paths.len) {
-        return Value{ .string = "" };
-    }
-    return Value{ .string = bc.target_framework_paths[@intCast(idx_i64)] };
-}
diff --git a/src/ir/comptime_vm.test.zig b/src/ir/comptime_vm.test.zig
index 5c88999b..d0fbcdaa 100644
--- a/src/ir/comptime_vm.test.zig
+++ b/src/ir/comptime_vm.test.zig
@@ -1314,12 +1314,12 @@ test "comptime_vm tryEval: pure function → Value; unsupported → null" {
     const v = vm.tryEval(alloc, &module, ok_id, null, null) orelse return error.VmShouldHaveHandledIt;
     try std.testing.expectEqual(@as(i64, 42), v.int);
 
-    // fn bad() { compiler_call() }  → an unported op → tryEval yields null (caller
-    // falls back to legacy). (box_any/unbox_any are now VM-native; compiler_call is
-    // still unported until Phase 4D.)
+    // fn bad() { vec_splat(...) }  → an unported op → tryEval yields null. The VM
+    // bails loudly on any op it does not model (never a silent default); vec_splat
+    // is a stable example of one.
     var fb2 = Fb.init(alloc, &.{}, .void);
     const c0 = fb2.block(&.{});
-    _ = fb2.add(c0, inst(.{ .compiler_call = .{ .name = 0, .args = &.{} } }, .void));
+    _ = fb2.add(c0, inst(.{ .vec_splat = .{ .operand = ref(0) } }, .void));
     _ = fb2.add(c0, inst(.ret_void, .void));
     const bad_id = module.addFunction(fb2.func);
 
@@ -1341,18 +1341,18 @@ test "comptime_vm exec: division by zero and unsupported op bail loudly" {
         try std.testing.expectEqual(@as(i64, 4), toI64(try v.run(&fb.func, &.{ fromI64(12), fromI64(3) })));
         try std.testing.expectError(error.DivisionByZero, v.run(&fb.func, &.{ fromI64(12), fromI64(0) }));
     }
-    // A not-yet-ported op (compiler_call) → Unsupported with the op name in `detail`.
+    // A not-yet-ported op (vec_splat) → Unsupported with the op name in `detail`.
     {
         var fb = Fb.init(std.testing.allocator, &.{}, .void);
         defer fb.deinit();
         const b0 = fb.block(&.{});
-        _ = fb.add(b0, inst(.{ .compiler_call = .{ .name = 0, .args = &.{} } }, .void));
+        _ = fb.add(b0, inst(.{ .vec_splat = .{ .operand = ref(0) } }, .void));
         _ = fb.add(b0, inst(.ret_void, .void));
 
         var v = vm.Vm.init(std.testing.allocator);
         defer v.deinit();
         try std.testing.expectError(error.Unsupported, v.run(&fb.func, &.{}));
-        try std.testing.expectEqualStrings("compiler_call", v.detail.?);
+        try std.testing.expectEqualStrings("vec_splat", v.detail.?);
     }
 }
 
diff --git a/src/ir/emit_llvm.zig b/src/ir/emit_llvm.zig
index 749468fb..3c38940b 100644
--- a/src/ir/emit_llvm.zig
+++ b/src/ir/emit_llvm.zig
@@ -1632,7 +1632,6 @@ pub const LLVMEmitter = struct {
 
             // ── Call extensions ───────────────────────────────────────
             .call_builtin => |bi| self.ops().emitCallBuiltin(instruction, bi),
-            .compiler_call => self.ops().emitCompilerCall(instruction),
             .call_closure => |call_op| self.ops().emitCallClosure(instruction, call_op),
 
             // ── Tuple ops ────────────────────────────────────────────
diff --git a/src/ir/inst.zig b/src/ir/inst.zig
index b1f41b2a..5816b9cd 100644
--- a/src/ir/inst.zig
+++ b/src/ir/inst.zig
@@ -207,7 +207,6 @@ pub const Op = union(enum) {
     call_indirect: CallIndirect,
     call_closure: CallIndirect,
     call_builtin: BuiltinCall,
-    compiler_call: CompilerCall,
 
     /// `#objc_call(ReturnT)(recv, sel, args...)` — dispatched through
     /// `objc_msgSend`. emit_llvm.zig synthesizes a per-call-site LLVM
@@ -473,11 +472,6 @@ pub const BuiltinId = enum(u16) {
     type_info,
 };
 
-pub const CompilerCall = struct {
-    name: u32, // StringPool id for qualified name (e.g. "BuildOptions.add_link_flag")
-    args: []const Ref,
-};
-
 pub const ClosureCreate = struct {
     func: FuncId, // trampoline function
     env: Ref, // allocated env pointer (or Ref.none for no captures)
diff --git a/src/ir/interp.zig b/src/ir/interp.zig
index 5cd0475e..12d46c45 100644
--- a/src/ir/interp.zig
+++ b/src/ir/interp.zig
@@ -200,9 +200,6 @@ pub const Interpreter = struct {
     // Mutable build configuration — set by LLVMEmitter, written by #run blocks
     build_config: ?*BuildConfig = null,
 
-    // Compiler hook registry for #compiler methods
-    hooks: compiler_hooks.Registry,
-
     // First op tag that bailed with InterpError, captured the first
     // time the interpreter unwinds so callers can surface "op=foo at
     // <file>:<offset>" alongside the bare error name. Static so it
@@ -234,15 +231,12 @@ pub const Interpreter = struct {
     }
 
     pub fn init(module: *const Module, alloc: Allocator) Interpreter {
-        var hooks = compiler_hooks.Registry.init(alloc);
-        hooks.registerDefaults();
         return .{
             .module = module,
             .alloc = alloc,
             .output = std.ArrayList(u8).empty,
             .heap = std.ArrayList([]u8).empty,
             .global_values = std.AutoHashMap(u32, Value).init(alloc),
-            .hooks = hooks,
         };
     }
 
@@ -268,7 +262,6 @@ pub const Interpreter = struct {
         self.output.deinit(self.alloc);
         self.call_chain.deinit(self.alloc);
         self.global_values.deinit();
-        self.hooks.deinit();
     }
 
     /// Write `val` to the raw host address `addr` using exactly the
@@ -1126,31 +1119,6 @@ pub const Interpreter = struct {
                 return self.execBuiltin(bi, frame, instruction.ty);
             },
 
-            // ── Compiler hook calls (#compiler methods) ────────
-            .compiler_call => |cc| {
-                const name = self.module.types.getString(@enumFromInt(cc.name));
-                if (self.hooks.get(name)) |hook| {
-                    // Resolve args from Ref to Value
-                    var resolved_args = std.ArrayList(Value).empty;
-                    defer resolved_args.deinit(self.alloc);
-                    for (cc.args) |arg| {
-                        resolved_args.append(self.alloc, frame.getRef(arg)) catch return error.CannotEvalComptime;
-                    }
-                    if (self.build_config) |bc| {
-                        const result = hook(self, resolved_args.items, bc, self.alloc) catch return bailDetail("#compiler hook returned an error (see hook impl)");
-                        return .{ .value = result };
-                    }
-                    return .{ .value = .void_val };
-                }
-                if (last_bail_detail == null) {
-                    // Capture which hook name failed so the host diag
-                    // surfaces "compiler_call: unknown hook 'X'" instead
-                    // of a bare CannotEvalComptime.
-                    last_bail_detail = "#compiler hook not registered (likely a target-specific BuildOptions setter)";
-                }
-                return error.CannotEvalComptime;
-            },
-
             // ── Struct GEP (field pointer) ─────────────────────
             .struct_gep => |fa| {
                 const base = frame.getRef(fa.base);
diff --git a/src/ir/lower/call.zig b/src/ir/lower/call.zig
index eafacae9..6af51f1f 100644
--- a/src/ir/lower/call.zig
+++ b/src/ir/lower/call.zig
@@ -494,14 +494,6 @@ pub fn lowerCall(self: *Lowering, c_in: *const ast.Call) Ref {
                     return self.lowerGenericCall(fd, func_name, c, args.items);
                 }
             }
-            // Check for #compiler free functions
-            if (self.program_index.fn_ast_map.get(func_name)) |fd_check| {
-                if (fd_check.body.data == .compiler_expr) {
-                    const ret_ty = if (fd_check.return_type) |rt| type_bridge.resolveAstType(rt, &self.module.types, &self.program_index.type_alias_map, &self.program_index.module_const_map) else TypeId.void;
-                    return self.builder.compilerCall(func_name, args.items, ret_ty);
-                }
-            }
-
             // Look up declared/extern function — try lazy lowering if not yet lowered
             {
                 // First attempt: function may already be declared (from scanDecls)
@@ -907,17 +899,6 @@ pub fn lowerCall(self: *Lowering, c_in: *const ast.Call) Ref {
                 // Try direct qualified name: StructName.method
                 const qualified = std.fmt.allocPrint(self.alloc, "{s}.{s}", .{ sname, fa.field }) catch fa.field;
 
-                // Generic #compiler method dispatch
-                if (self.program_index.fn_ast_map.get(qualified)) |method_fd| {
-                    if (method_fd.body.data == .compiler_expr) {
-                        const ret_ty = if (method_fd.return_type) |rt|
-                            type_bridge.resolveAstType(rt, &self.module.types, &self.program_index.type_alias_map, &self.program_index.module_const_map)
-                        else
-                            .void;
-                        return self.builder.compilerCall(qualified, method_args.items, ret_ty);
-                    }
-                }
-
                 // Generic-struct instance method: select the body via the
                 // instance's STAMPED author (CP-4), so the dispatched method is
                 // the one authored alongside this instance's layout — never the
diff --git a/src/ir/module.zig b/src/ir/module.zig
index 8d643010..478dffe5 100644
--- a/src/ir/module.zig
+++ b/src/ir/module.zig
@@ -570,12 +570,6 @@ pub const Builder = struct {
         return self.emit(.{ .call_builtin = .{ .builtin = builtin, .args = owned } }, ret_ty);
     }
 
-    pub fn compilerCall(self: *Builder, name: []const u8, args: []const Ref, ret_ty: TypeId) Ref {
-        const name_id = self.module.types.strings.intern(self.module.alloc, name);
-        const owned = self.module.slice_arena.allocator().dupe(Ref, args) catch unreachable;
-        return self.emit(.{ .compiler_call = .{ .name = @intFromEnum(name_id), .args = owned } }, ret_ty);
-    }
-
     // ── Closure ─────────────────────────────────────────────────────
 
     pub fn closureCreate(self: *Builder, func_id: FuncId, env: Ref, ty: TypeId) Ref {
diff --git a/src/ir/print.zig b/src/ir/print.zig
index 483d4dba..95b617bc 100644
--- a/src/ir/print.zig
+++ b/src/ir/print.zig
@@ -336,13 +336,6 @@ fn printInst(instruction: *const Inst, ref_idx: u32, tt: *const TypeTable, write
                 a.clobbers.len,
             });
         },
-        .compiler_call => |cc| {
-            const name = tt.getString(@enumFromInt(cc.name));
-            try writer.print("compiler_call \"{s}\"(", .{name});
-            try writeArgs(cc.args, writer);
-            try writer.writeAll(") : ");
-        },
-
         // ── Closure ─────────────────────────────────────────────
         .closure_create => |cc| {
             try writer.print("closure_create @{d}", .{cc.func.index()});