diff --git a/CLAUDE.md b/CLAUDE.md
index 54c8d0de08..2cfcaa523f 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -8,7 +8,7 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 
 Perry is a native TypeScript compiler written in Rust that compiles TypeScript source code directly to native executables. It uses SWC for TypeScript parsing and LLVM for code generation.
 
-**Current Version:** 0.5.1292
+**Current Version:** 0.5.1293
 
 
 ## TypeScript Parity Status
diff --git a/Cargo.lock b/Cargo.lock
index 8af8536395..2ad3a86324 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -5547,7 +5547,7 @@ checksum = "9b4f627cb1b25917193a259e49bdad08f671f8d9708acfd5fe0a8c1455d87220"
 
 [[package]]
 name = "perry"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "anyhow",
  "base64",
@@ -5607,14 +5607,14 @@ dependencies = [
 
 [[package]]
 name = "perry-api-manifest"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "serde",
 ]
 
 [[package]]
 name = "perry-audio-miniaudio"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "cc",
  "libc",
@@ -5622,7 +5622,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "anyhow",
  "inkwell",
@@ -5639,7 +5639,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-arkts"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "anyhow",
  "perry-hir",
@@ -5647,7 +5647,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-glance"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "anyhow",
  "perry-hir",
@@ -5655,7 +5655,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-js"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "anyhow",
  "perry-dispatch",
@@ -5664,7 +5664,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-swiftui"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "anyhow",
  "perry-hir",
@@ -5672,7 +5672,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-wasm"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "anyhow",
  "base64",
@@ -5684,7 +5684,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-wear-tiles"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "anyhow",
  "perry-hir",
@@ -5692,7 +5692,7 @@ dependencies = [
 
 [[package]]
 name = "perry-container-compose"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "anyhow",
  "async-trait",
@@ -5721,14 +5721,14 @@ dependencies = [
 
 [[package]]
 name = "perry-container-e2e"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "anyhow",
 ]
 
 [[package]]
 name = "perry-diagnostics"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "serde",
  "serde_json",
@@ -5736,7 +5736,7 @@ dependencies = [
 
 [[package]]
 name = "perry-dispatch"
-version = "0.5.1292"
+version = "0.5.1293"
 
 [[package]]
 name = "perry-doc-fixture-my-bindings"
@@ -5747,7 +5747,7 @@ dependencies = [
 
 [[package]]
 name = "perry-doc-tests"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "anyhow",
  "clap",
@@ -5762,7 +5762,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-ads"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "block2",
  "objc2",
@@ -5772,7 +5772,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-argon2"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "argon2",
  "perry-ffi",
@@ -5780,7 +5780,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-axios"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "perry-ffi",
  "reqwest",
@@ -5789,7 +5789,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-bcrypt"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "bcrypt",
  "perry-ffi",
@@ -5797,7 +5797,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-better-sqlite3"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "perry-ffi",
  "rusqlite",
@@ -5805,7 +5805,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-cheerio"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "perry-ffi",
  "scraper",
@@ -5813,7 +5813,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-commander"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "perry-ffi",
  "perry-runtime",
@@ -5821,7 +5821,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-cron"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "chrono",
  "cron",
@@ -5831,7 +5831,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-dayjs"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "chrono",
  "perry-ffi",
@@ -5839,7 +5839,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-decimal"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "perry-ffi",
  "rust_decimal",
@@ -5847,7 +5847,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-dotenv"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "perry-ffi",
  "serde_json",
@@ -5855,7 +5855,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-ethers"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "perry-ffi",
  "rand 0.10.1",
@@ -5863,7 +5863,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-events"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "perry-ffi",
  "perry-runtime",
@@ -5871,14 +5871,14 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-exponential-backoff"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "perry-ffi",
 ]
 
 [[package]]
 name = "perry-ext-fastify"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "bytes",
  "http-body-util",
@@ -5896,7 +5896,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-fetch"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "bytes",
  "lazy_static",
@@ -5909,7 +5909,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-http"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "bytes",
  "h2",
@@ -5933,7 +5933,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-ioredis"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "lazy_static",
  "perry-ffi",
@@ -5943,7 +5943,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-jsonwebtoken"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "base64",
  "jsonwebtoken",
@@ -5954,7 +5954,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-lru-cache"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "lru",
  "perry-ffi",
@@ -5963,7 +5963,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-moment"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "chrono",
  "perry-ffi",
@@ -5971,7 +5971,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-mongodb"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "bson",
  "futures-util",
@@ -5983,7 +5983,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-mysql2"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "chrono",
  "perry-ffi",
@@ -5993,7 +5993,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-nanoid"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "nanoid",
  "perry-ffi",
@@ -6002,7 +6002,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-net"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "bytes",
  "perry-ffi",
@@ -6015,7 +6015,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-node-forge"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "const-oid 0.9.6",
  "der 0.7.10",
@@ -6034,7 +6034,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-nodemailer"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "lettre",
  "perry-ffi",
@@ -6044,7 +6044,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-pdf"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "perry-ffi",
  "printpdf",
@@ -6052,7 +6052,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-pg"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "perry-ffi",
  "sqlx",
@@ -6061,7 +6061,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-ratelimit"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "governor",
  "perry-ffi",
@@ -6069,7 +6069,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-sharp"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "fast_image_resize",
  "image",
@@ -6079,14 +6079,14 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-slugify"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "perry-ffi",
 ]
 
 [[package]]
 name = "perry-ext-streams"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "lazy_static",
  "perry-ffi",
@@ -6095,7 +6095,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-undici"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "perry-ffi",
  "perry-runtime",
@@ -6104,7 +6104,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-uuid"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "perry-ffi",
  "uuid",
@@ -6112,7 +6112,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-validator"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "perry-ffi",
  "regex",
@@ -6122,7 +6122,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-ws"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "futures-util",
  "lazy_static",
@@ -6135,7 +6135,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-zlib"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "brotli",
  "flate2",
@@ -6145,7 +6145,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ffi"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "dashmap",
  "once_cell",
@@ -6154,7 +6154,7 @@ dependencies = [
 
 [[package]]
 name = "perry-hir"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "anyhow",
  "perry-api-manifest",
@@ -6172,7 +6172,7 @@ dependencies = [
 
 [[package]]
 name = "perry-parser"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "anyhow",
  "perry-diagnostics",
@@ -6184,7 +6184,7 @@ dependencies = [
 
 [[package]]
 name = "perry-runtime"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "anyhow",
  "base64",
@@ -6226,14 +6226,14 @@ dependencies = [
 
 [[package]]
 name = "perry-runtime-static"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "perry-runtime",
 ]
 
 [[package]]
 name = "perry-stdlib"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "aes 0.8.4",
  "aes 0.9.1",
@@ -6328,14 +6328,14 @@ dependencies = [
 
 [[package]]
 name = "perry-stdlib-static"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "perry-stdlib",
 ]
 
 [[package]]
 name = "perry-transform"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "anyhow",
  "perry-hir",
@@ -6344,14 +6344,14 @@ dependencies = [
 
 [[package]]
 name = "perry-ui"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "perry-ui-model",
 ]
 
 [[package]]
 name = "perry-ui-android"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "base64",
  "itoa",
@@ -6368,7 +6368,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-geisterhand"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "rand 0.10.1",
  "serde",
@@ -6378,7 +6378,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-gtk4"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "base64",
  "cairo-rs 0.22.0",
@@ -6401,7 +6401,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-ios"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "base64",
  "block2",
@@ -6417,7 +6417,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-macos"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "base64",
  "block2",
@@ -6432,7 +6432,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-model"
-version = "0.5.1292"
+version = "0.5.1293"
 
 [[package]]
 name = "perry-ui-test"
@@ -6443,11 +6443,11 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-testkit"
-version = "0.5.1292"
+version = "0.5.1293"
 
 [[package]]
 name = "perry-ui-tvos"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "base64",
  "block2",
@@ -6463,7 +6463,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-visionos"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "base64",
  "block2",
@@ -6479,7 +6479,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-watchos"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "block2",
  "libc",
@@ -6492,7 +6492,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-windows"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "base64",
  "libc",
@@ -6509,14 +6509,14 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-windows-winui"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "perry-ui-windows",
 ]
 
 [[package]]
 name = "perry-updater"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "anyhow",
  "base64",
@@ -6532,7 +6532,7 @@ dependencies = [
 
 [[package]]
 name = "perry-wasm-host"
-version = "0.5.1292"
+version = "0.5.1293"
 dependencies = [
  "wasmi",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 3270356078..f4f6de0a43 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -315,7 +315,7 @@ codegen-units = 16
 codegen-units = 16
 
 [workspace.package]
-version = "0.5.1292"
+version = "0.5.1293"
 edition = "2021"
 license = "MIT"
 repository = "https://github.com/PerryTS/perry"
diff --git a/changelog.d/7515-class-ctor-dead-field-init.md b/changelog.d/7515-class-ctor-dead-field-init.md
new file mode 100644
index 0000000000..591c6cc795
--- /dev/null
+++ b/changelog.d/7515-class-ctor-dead-field-init.md
@@ -0,0 +1,68 @@
+### Codegen: the dead-default-field-init elision now reaches user-written constructors (#7512)
+
+#7469 elides the default-`undefined` write for a class field the constructor's
+own prologue provably overwrites. Its changelog said it covered "plain user
+ctors like `constructor(a, b) { this.a = a; this.b = b }`". It did not, and
+could not: `ctor_prologue_param_assigned_fields` matched the prologue on
+`Expr::PropertySet`, and **no user syntax lowers to that node**.
+`perry-hir/src/lower/lower_expr/assignment.rs` turns every source-level
+`obj.prop = value` — `this.v = v` included — into the spec `PutValue` node
+`Expr::PutValueSet`. `Expr::PropertySet` is emitted only by *synthesized* HIR,
+which is exactly what the anon-shape object-literal constructor
+(`lower/context.rs::mint_anon_shape_class`) is built from. The elision was
+therefore measured on the one construction form it reached, and was
+structurally unreachable for the declared class it was documented as covering.
+
+The visible consequence is the anomaly filed as #7512: `new Node(v, w)` with two
+declared `number` fields was **slower** than the equivalent `{v, w}` literal, so
+the most statically-known construction form in the language was the least
+optimized one. Emitted-IR census of the two constructors, same workload, same
+compiler (`--trace llvm`):
+
+| per construction | `{v, w}` literal | `new Node(v, w)` before | after |
+|---|--:|--:|--:|
+| field-store IC diamonds | 2 | **4** | 2 |
+| `js_typed_feedback_class_field_set_guard` | 2 | 2 | 0 |
+| `js_class_field_set_fallback` | 2 | 2 | 0 |
+| `js_array_numeric_value_to_raw_f64` | 0 | 4 | 2 |
+| constructor body, IR lines | 111 | **314** | 157 |
+
+The two extra diamonds each stored a compile-time-constant `undefined` that the
+next two statements overwrote. Both took the cold by-name arm on *every*
+construction rather than occasionally: a freshly allocated instance carries no
+typed-shape descriptor (`js_gc_init_typed_shape_layout` runs after the
+constructor returns), so a `requires_raw_f64` set-guard on a declared `number`
+field cannot pass, and `js_class_field_set_fallback` — a feedback-fallback
+record plus a linear-key-search `js_object_set_field_by_name` — ran twice per
+object. A class whose fields are declared `any` paid the same two dead diamonds.
+
+The fix is one recognizer, `prologue_assigned_field`, accepting both spellings
+of `this.<field> = <plain parameter>`. The proof obligation is unchanged and is
+about the *operands*, not the store opcode: `This` and `LocalGet` of a plain
+parameter cannot throw, allocate, or observe `this`, so the prologue write is
+reached before any other effect of the constructor. `PutValueSet` additionally
+requires a constant string key and a `This` receiver. Every existing refusal
+still applies — derived classes, field initializers, computed keys, parameter
+defaults, setter-shadowed fields, and any statement that breaks the leading run.
+
+The elided write is not an observable `[[Set]]`, so it cannot change how many
+times an accessor runs. A class field declaration is a `CreateDataProperty` — a
+DEFINE — so it never consults an inherited accessor, and it installs an own data
+property that the prologue assignment then writes directly.
+`test-files/test_class_field_init_proto_setter.ts` pins that at the execution
+level for the case the compile-time `class.setters` check structurally cannot
+see: a setter installed on `C.prototype` *after* compilation runs **zero** times,
+byte-identical to Node, both before and after this change.
+
+Behaviour is unchanged elsewhere too: an 11-case semantics probe (unassigned
+fields still read `undefined`, `Object.keys`/JSON shape, declared-accessor
+shadowing, derived classes, interrupted prologues, post-construction
+reassignment, 200-instance shared-shape consistency) produces byte-identical
+output before and after, and an A/B of every `test-files/*.ts` containing a
+`constructor(` finds no drift between the two compilers.
+
+**Not fixed here, and worth its own ticket:** the residual gap is an ordering
+one. `lower_call/new.rs` emits `js_gc_init_typed_shape_layout` *after* the
+constructor call, so no raw-f64-declared class-field store inside any
+constructor can ever pass its guard — the surviving real stores still take
+`js_put_value_set`. That belongs with #7510's construction-path item.
diff --git a/crates/perry-codegen/src/lower_call/field_init.rs b/crates/perry-codegen/src/lower_call/field_init.rs
index 92bbeef0dc..32ffad47dd 100644
--- a/crates/perry-codegen/src/lower_call/field_init.rs
+++ b/crates/perry-codegen/src/lower_call/field_init.rs
@@ -13,15 +13,100 @@ use crate::expr::{lower_expr, FnCtx};
 use crate::nanbox::{double_literal, POINTER_MASK_I64};
 use crate::types::{DOUBLE, I32, I64};
 
+/// The field name a constructor-prologue statement assigns from a plain
+/// parameter, or `None` if the statement is not of that shape.
+///
+/// **Two HIR shapes mean the same thing here, and matching only one of them is
+/// what #7512 was** (`new Node(v, w)` measured 63% slower than the equivalent
+/// `{v, w}` literal, the reverse of the expected ordering):
+///
+/// - `Expr::PropertySet` is what the compiler SYNTHESIZES. Every anon-shape
+///   object-literal constructor (`lower/context.rs::mint_anon_shape_class`)
+///   and the destructuring lowering emit it directly.
+/// - `Expr::PutValueSet` is what USER SOURCE lowers to. `lower_expr`'s
+///   assignment arm (`perry-hir/src/lower/lower_expr/assignment.rs`) turns
+///   *every* source-level `obj.prop = value` — `this.v = v` in a hand-written
+///   constructor included — into the spec `PutValue` node. Nothing a user can
+///   type produces `Expr::PropertySet`.
+///
+/// So #7469's elision, which only ever matched `PropertySet`, fired on the
+/// synthesized literal ctor and was structurally unreachable for the declared
+/// class it was documented as covering. The class paid two extra full
+/// class-field-set IC diamonds per construction — a guard call plus a
+/// by-name `js_class_field_set_fallback` each, since a fresh instance has no
+/// typed-shape descriptor yet and the raw-f64 guard therefore cannot pass —
+/// writing a compile-time-constant `undefined` that the next two statements
+/// overwrite.
+///
+/// The proof obligation is identical for both shapes and is entirely about the
+/// *operand* expressions, not the store opcode: `This` and `LocalGet(<plain
+/// param>)` cannot throw, allocate, or observe `this`, so the assignment is
+/// reached before any other effect of the constructor.
+///
+/// **What the elided write is NOT** (the obvious objection, and it is
+/// measurably wrong — `test-files/test_class_field_init_proto_setter.ts`): it
+/// is not an observable `[[Set]]`, so eliding it cannot change how many times
+/// an accessor runs. A class field declaration is a `CreateDataProperty` — a
+/// DEFINE — per `ClassFieldDefinitionRecord` evaluation, so it never consults
+/// an inherited accessor, and it installs an OWN data property that the
+/// prologue's assignment then writes directly rather than dispatching past.
+/// A setter installed on the prototype *after* compilation (which the
+/// `class.setters` check below cannot see, by construction) runs **zero**
+/// times either way, matching Node exactly. The reading in which the field
+/// init is a `[[Set]]` and the setter therefore fires twice is the legacy
+/// `useDefineForClassFields: false` behaviour, which neither this compiler nor
+/// Node implements. The `class.setters` refusal below exists for the separate
+/// case of a setter the class DECLARES, where Perry's own class-field-set
+/// lowering does dispatch to the synthesized `__set_<name>` method.
+///
+/// `PutValueSet` additionally requires a constant string key (a computed key
+/// is an arbitrary expression that can run user code) and `receiver` to be
+/// `This` as well, since codegen evaluates both.
+fn prologue_assigned_field<'a>(
+    stmt: &'a Stmt,
+    param_ids: &std::collections::HashSet<u32>,
+) -> Option<&'a str> {
+    let is_plain_param = |e: &Expr| matches!(e, Expr::LocalGet(id) if param_ids.contains(id));
+    match stmt {
+        // Synthesized (anon-shape ctor, destructuring lowering).
+        Stmt::Expr(Expr::PropertySet {
+            object,
+            property,
+            value,
+        }) if matches!(object.as_ref(), Expr::This) && is_plain_param(value.as_ref()) => {
+            Some(property.as_str())
+        }
+        // User-written `this.f = p;`.
+        Stmt::Expr(Expr::PutValueSet {
+            target,
+            key,
+            value,
+            receiver,
+            strict: _,
+        }) if matches!(target.as_ref(), Expr::This)
+            && matches!(receiver.as_ref(), Expr::This)
+            && is_plain_param(value.as_ref()) =>
+        {
+            match key.as_ref() {
+                Expr::String(property) => Some(property.as_str()),
+                _ => None,
+            }
+        }
+        _ => None,
+    }
+}
+
 /// Field names whose default-`undefined` initializer write is provably dead
 /// because the class's own constructor unconditionally overwrites them before
-/// anything can observe `this` (#7469).
+/// anything can observe `this` (#7469; extended to user-written constructors
+/// by #7512).
 ///
 /// A field declared without an initializer must normally be written as
 /// `undefined` in the init phase (#486: `new C().x === undefined` is spec, not
 /// zero-bytes-from-the-allocator). But the most common constructor shape —
-/// including every synthesized anon-shape literal ctor
-/// (`lower/context.rs::mint_anon_shape_class`) — opens with a run of plain
+/// every synthesized anon-shape literal ctor
+/// (`lower/context.rs::mint_anon_shape_class`), and the hand-written
+/// `constructor(v, w) { this.v = v; this.w = w }` — opens with a run of plain
 /// `this.f = <param>` statements. For those fields the `undefined` write is a
 /// dead store: it is overwritten before any code that could read `this.f`
 /// runs. On `churn.ts` that dead store was 2 of the 4 guarded field-store
@@ -49,18 +134,18 @@ use crate::types::{DOUBLE, I32, I64};
 /// - **Every constructor parameter is plain**: no default (a default expression
 ///   evaluates before the prologue and, in the general lowering, could observe
 ///   `this`), no rest, no decorators, no `arguments` materialization.
-/// - **No setter shares a name with a prologue-assigned field** — the
-///   PropertySet would dispatch to the setter instead of writing the slot, and
-///   the elided `undefined` write was the only slot write.
+/// - **No setter shares a name with a prologue-assigned field** — the store
+///   would dispatch to the setter instead of writing the slot, and the elided
+///   `undefined` write was the only slot write.
 /// - The field itself is public and non-computed (`is_private` false,
 ///   `key_expr` none).
 ///
-/// The prologue is the maximal leading run of
-/// `Stmt::Expr(PropertySet { object: This, property, value: LocalGet(<param>) })`
-/// statements. A `LocalGet` of a plain parameter cannot throw, allocate, or
-/// observe `this`, so every field it assigns is written before ANY other
-/// effect of the constructor — which is exactly the guarantee that makes the
-/// earlier `undefined` write dead.
+/// The prologue is the maximal leading run of statements that
+/// [`prologue_assigned_field`] recognizes as `this.<f> = <plain param>`. A
+/// `LocalGet` of a plain parameter cannot throw, allocate, or observe `this`,
+/// so every field it assigns is written before ANY other effect of the
+/// constructor — which is exactly the guarantee that makes the earlier
+/// `undefined` write dead.
 fn ctor_prologue_param_assigned_fields(
     class: &perry_hir::Class,
 ) -> std::collections::HashSet<String> {
@@ -91,17 +176,11 @@ fn ctor_prologue_param_assigned_fields(
     let param_ids: std::collections::HashSet<_> = ctor.params.iter().map(|p| p.id).collect();
     let mut assigned = std::collections::HashSet::new();
     for stmt in &ctor.body {
-        match stmt {
-            Stmt::Expr(Expr::PropertySet {
-                object,
-                property,
-                value,
-            }) if matches!(object.as_ref(), Expr::This)
-                && matches!(value.as_ref(), Expr::LocalGet(id) if param_ids.contains(id)) =>
-            {
-                assigned.insert(property.clone());
+        match prologue_assigned_field(stmt, &param_ids) {
+            Some(property) => {
+                assigned.insert(property.to_string());
             }
-            _ => break,
+            None => break,
         }
     }
     if assigned.is_empty() {
@@ -449,3 +528,6 @@ pub(crate) fn apply_field_initializers_recursive(
     }
     Ok(())
 }
+
+#[cfg(test)]
+mod tests;
diff --git a/crates/perry-codegen/src/lower_call/field_init/tests.rs b/crates/perry-codegen/src/lower_call/field_init/tests.rs
new file mode 100644
index 0000000000..1d8b5d601b
--- /dev/null
+++ b/crates/perry-codegen/src/lower_call/field_init/tests.rs
@@ -0,0 +1,314 @@
+//! Unit tests for the #7469 / #7512 dead-default-field-init predicate.
+//!
+//! The whole point of these is the pair
+//! `synthesized_and_user_ctor_prologues_agree` pins: the two HIR spellings of
+//! `this.f = <param>` must be treated identically. #7469 shipped matching only
+//! the SYNTHESIZED one, which is why the elision was measured working on an
+//! object literal and was structurally unreachable for the hand-written class
+//! its own changelog claimed to cover (#7512).
+
+use super::*;
+use perry_hir::types::Type;
+use perry_hir::{Class, ClassField, Function, Param};
+
+fn param(id: u32, name: &str) -> Param {
+    Param {
+        id,
+        name: name.to_string(),
+        ty: Type::Number,
+        default: None,
+        decorators: Vec::new(),
+        is_rest: false,
+        arguments_object: None,
+    }
+}
+
+fn field(name: &str) -> ClassField {
+    ClassField {
+        name: name.to_string(),
+        key_expr: None,
+        ty: Type::Number,
+        init: None,
+        is_private: false,
+        is_readonly: false,
+        decorators: Vec::new(),
+    }
+}
+
+fn func(params: Vec<Param>, body: Vec<Stmt>) -> Function {
+    Function {
+        id: 0,
+        name: "constructor".to_string(),
+        type_params: Vec::new(),
+        params,
+        return_type: Type::Void,
+        body,
+        is_async: false,
+        is_generator: false,
+        is_strict: false,
+        is_exported: false,
+        captures: Vec::new(),
+        decorators: Vec::new(),
+        was_plain_async: false,
+        was_unrolled: false,
+    }
+}
+
+fn class(fields: Vec<ClassField>, constructor: Option<Function>) -> Class {
+    Class {
+        id: 0,
+        name: "Node".to_string(),
+        type_params: Vec::new(),
+        extends: None,
+        extends_name: None,
+        native_extends: None,
+        extends_expr: None,
+        heritage_lexically_shadowed: false,
+        fields,
+        constructor,
+        methods: Vec::new(),
+        getters: Vec::new(),
+        setters: Vec::new(),
+        static_fields: Vec::new(),
+        static_methods: Vec::new(),
+        computed_members: Vec::new(),
+        decorators: Vec::new(),
+        is_exported: false,
+        aliases: Vec::new(),
+        is_nested: false,
+        alloc_width_hint: 0,
+        static_accessor_names: Vec::new(),
+        static_accessor_fn_ids: Vec::new(),
+    }
+}
+
+/// The shape a USER writes. `this.v = v` lowers to `Expr::PutValueSet`
+/// (`perry-hir/src/lower/lower_expr/assignment.rs`), never
+/// `Expr::PropertySet` — no source syntax produces the latter.
+fn user_this_assign(property: &str, param_id: u32) -> Stmt {
+    Stmt::Expr(Expr::PutValueSet {
+        target: Box::new(Expr::This),
+        key: Box::new(Expr::String(property.to_string())),
+        value: Box::new(Expr::LocalGet(param_id)),
+        receiver: Box::new(Expr::This),
+        strict: true,
+    })
+}
+
+/// The shape the COMPILER synthesizes for an anon-shape object-literal
+/// constructor (`lower/context.rs::mint_anon_shape_class`).
+fn synthesized_this_assign(property: &str, param_id: u32) -> Stmt {
+    Stmt::Expr(Expr::PropertySet {
+        object: Box::new(Expr::This),
+        property: property.to_string(),
+        value: Box::new(Expr::LocalGet(param_id)),
+    })
+}
+
+fn sorted(set: std::collections::HashSet<String>) -> Vec<String> {
+    let mut v: Vec<String> = set.into_iter().collect();
+    v.sort();
+    v
+}
+
+/// #7512: a hand-written `constructor(v, w) { this.v = v; this.w = w }` must
+/// qualify. Before the fix the predicate matched only `Expr::PropertySet`, so
+/// a declared class emitted two extra class-field-set IC diamonds per
+/// construction that the equivalent `{v, w}` literal did not — making the more
+/// statically-known construction form the slower one.
+#[test]
+fn user_written_ctor_prologue_qualifies() {
+    let c = class(
+        vec![field("v"), field("w")],
+        Some(func(
+            vec![param(1, "v"), param(2, "w")],
+            vec![user_this_assign("v", 1), user_this_assign("w", 2)],
+        )),
+    );
+    assert_eq!(
+        sorted(ctor_prologue_param_assigned_fields(&c)),
+        vec!["v".to_string(), "w".to_string()]
+    );
+}
+
+/// The regression pin for the ordering #7512 is about: the object-literal form
+/// and the class form of the same program must elide the same field set. If
+/// this ever diverges again, one construction form is silently paying
+/// bookkeeping the other does not.
+#[test]
+fn synthesized_and_user_ctor_prologues_agree() {
+    let synthesized = class(
+        vec![field("v"), field("w")],
+        Some(func(
+            vec![param(1, "v"), param(2, "w")],
+            vec![
+                synthesized_this_assign("v", 1),
+                synthesized_this_assign("w", 2),
+            ],
+        )),
+    );
+    let user = class(
+        vec![field("v"), field("w")],
+        Some(func(
+            vec![param(1, "v"), param(2, "w")],
+            vec![user_this_assign("v", 1), user_this_assign("w", 2)],
+        )),
+    );
+    let synthesized_fields = sorted(ctor_prologue_param_assigned_fields(&synthesized));
+    assert_eq!(synthesized_fields, vec!["v".to_string(), "w".to_string()]);
+    assert_eq!(
+        synthesized_fields,
+        sorted(ctor_prologue_param_assigned_fields(&user))
+    );
+}
+
+/// The prologue is the MAXIMAL LEADING run: a statement that is not a plain
+/// `this.f = <param>` ends it, and every field assigned after it keeps its
+/// default `undefined` write.
+#[test]
+fn prologue_stops_at_the_first_non_matching_statement() {
+    let c = class(
+        vec![field("v"), field("w")],
+        Some(func(
+            vec![param(1, "v"), param(2, "w")],
+            vec![
+                user_this_assign("v", 1),
+                // A call can allocate, throw, and observe `this`, so `w`'s
+                // default write is not provably dead.
+                Stmt::Expr(Expr::Call {
+                    callee: Box::new(Expr::LocalGet(9)),
+                    args: Vec::new(),
+                    type_args: Vec::new(),
+                    byte_offset: 0,
+                }),
+                user_this_assign("w", 2),
+            ],
+        )),
+    );
+    assert_eq!(
+        sorted(ctor_prologue_param_assigned_fields(&c)),
+        vec!["v".to_string()]
+    );
+}
+
+/// A non-parameter RHS is not covered by the "cannot throw, allocate, or
+/// observe `this`" argument, so it does not open a prologue.
+#[test]
+fn non_param_rhs_does_not_qualify() {
+    let c = class(
+        vec![field("v")],
+        Some(func(
+            vec![param(1, "v")],
+            vec![Stmt::Expr(Expr::PutValueSet {
+                target: Box::new(Expr::This),
+                key: Box::new(Expr::String("v".to_string())),
+                // A body local, not a constructor parameter.
+                value: Box::new(Expr::LocalGet(77)),
+                receiver: Box::new(Expr::This),
+                strict: true,
+            })],
+        )),
+    );
+    assert!(ctor_prologue_param_assigned_fields(&c).is_empty());
+}
+
+/// A computed key (`this[k] = p`) evaluates an arbitrary expression to produce
+/// the key, so it neither names a field statically nor is effect-free.
+#[test]
+fn computed_key_put_value_set_does_not_qualify() {
+    let c = class(
+        vec![field("v")],
+        Some(func(
+            vec![param(1, "v")],
+            vec![Stmt::Expr(Expr::PutValueSet {
+                target: Box::new(Expr::This),
+                key: Box::new(Expr::LocalGet(5)),
+                value: Box::new(Expr::LocalGet(1)),
+                receiver: Box::new(Expr::This),
+                strict: true,
+            })],
+        )),
+    );
+    assert!(ctor_prologue_param_assigned_fields(&c).is_empty());
+}
+
+/// `PutValueSet` carries the object in both `target` and `receiver` and
+/// codegen evaluates both; a receiver that is not `this` is a different
+/// operation and must not be read as a prologue field write.
+#[test]
+fn non_this_receiver_does_not_qualify() {
+    let c = class(
+        vec![field("v")],
+        Some(func(
+            vec![param(1, "v")],
+            vec![Stmt::Expr(Expr::PutValueSet {
+                target: Box::new(Expr::This),
+                key: Box::new(Expr::String("v".to_string())),
+                value: Box::new(Expr::LocalGet(1)),
+                receiver: Box::new(Expr::LocalGet(4)),
+                strict: true,
+            })],
+        )),
+    );
+    assert!(ctor_prologue_param_assigned_fields(&c).is_empty());
+}
+
+/// A same-named setter swallows the prologue store, leaving the elided
+/// `undefined` as the only write that ever reached the slot.
+#[test]
+fn setter_shadowed_field_refuses_the_elision() {
+    let mut c = class(
+        vec![field("v"), field("w")],
+        Some(func(
+            vec![param(1, "v"), param(2, "w")],
+            vec![user_this_assign("v", 1), user_this_assign("w", 2)],
+        )),
+    );
+    c.setters
+        .push(("v".to_string(), func(vec![param(3, "x")], Vec::new())));
+    assert!(ctor_prologue_param_assigned_fields(&c).is_empty());
+}
+
+/// A parameter default evaluates before the prologue and can, in the general
+/// lowering, observe `this`.
+#[test]
+fn param_default_refuses_the_elision() {
+    let mut params = vec![param(1, "v"), param(2, "w")];
+    params[1].default = Some(Expr::Number(0.0));
+    let c = class(
+        vec![field("v"), field("w")],
+        Some(func(
+            params,
+            vec![user_this_assign("v", 1), user_this_assign("w", 2)],
+        )),
+    );
+    assert!(ctor_prologue_param_assigned_fields(&c).is_empty());
+}
+
+/// A field carrying an initializer expression means the init phase runs user
+/// code that may legally read an earlier field.
+#[test]
+fn field_initializer_refuses_the_elision() {
+    let mut fields = vec![field("v"), field("w")];
+    fields[1].init = Some(Expr::Number(1.0));
+    let c = class(
+        fields,
+        Some(func(
+            vec![param(1, "v"), param(2, "w")],
+            vec![user_this_assign("v", 1), user_this_assign("w", 2)],
+        )),
+    );
+    assert!(ctor_prologue_param_assigned_fields(&c).is_empty());
+}
+
+/// A derived class has its own `super()` machinery between the field-init
+/// phase and the constructor body.
+#[test]
+fn derived_class_refuses_the_elision() {
+    let mut c = class(
+        vec![field("v")],
+        Some(func(vec![param(1, "v")], vec![user_this_assign("v", 1)])),
+    );
+    c.extends_name = Some("Base".to_string());
+    assert!(ctor_prologue_param_assigned_fields(&c).is_empty());
+}
diff --git a/test-files/test_class_field_init_proto_setter.ts b/test-files/test_class_field_init_proto_setter.ts
new file mode 100644
index 0000000000..405f35ab6d
--- /dev/null
+++ b/test-files/test_class_field_init_proto_setter.ts
@@ -0,0 +1,89 @@
+// #7512 / #7515: the dead-default-field-init elision must not change how many
+// times an accessor runs.
+//
+// A setter installed on `C.prototype` AFTER compilation is invisible to the
+// compile-time `class.setters` check that guards the elision, so this pins the
+// observable behaviour directly rather than through that check.
+//
+// The spec answer is ZERO setter calls: a class field declaration (`v;`) is a
+// CreateDataProperty — a DEFINE, not a [[Set]] — so it never consults an
+// inherited accessor, and it installs an OWN data property that the
+// constructor's `this.v = v` then writes directly. Eliding the default write
+// therefore removes nothing observable. (The "field init is a [[Set]]" reading
+// is the legacy `useDefineForClassFields: false` behaviour, which is not what
+// this compiler or Node implements.)
+
+let calls = 0;
+let seen = "";
+
+class C {
+  v: number;
+  w: number;
+  constructor(v: number, w: number) {
+    this.v = v;
+    this.w = w;
+  }
+}
+
+Object.defineProperty(C.prototype, "v", {
+  configurable: true,
+  set(x: any) {
+    calls = calls + 1;
+    seen = seen + "[" + String(x) + "]";
+  },
+  get(): any {
+    return 999;
+  },
+});
+
+const c1 = new C(1, 2);
+console.log("setter_calls", calls);
+console.log("setter_args", seen);
+console.log("read_v", c1.v);
+console.log("read_w", c1.w);
+
+// Per-construction and stable across instances.
+const c2 = new C(3, 4);
+console.log("setter_calls_after_2", calls);
+console.log("read_v2", c2.v, "read_w2", c2.w);
+
+// A setter on a SEPARATE prototype the class does not declare, reached through
+// the same post-compilation route, on a field the prologue assigns second.
+let wCalls = 0;
+
+class D {
+  a: number;
+  b: number;
+  constructor(a: number, b: number) {
+    this.a = a;
+    this.b = b;
+  }
+}
+
+Object.defineProperty(D.prototype, "b", {
+  configurable: true,
+  set(x: any) {
+    wCalls = wCalls + 1;
+  },
+  get(): any {
+    return -1;
+  },
+});
+
+const d = new D(8, 9);
+console.log("d_setter_calls", wCalls);
+console.log("d", d.a, d.b);
+
+// A field the prologue does NOT assign still reads `undefined`.
+class E {
+  a: number;
+  b: number;
+  c: number;
+  constructor(a: number, b: number) {
+    this.a = a;
+    this.b = b;
+  }
+}
+
+const e = new E(5, 6);
+console.log("e", e.a, e.b, String(e.c), e.c === undefined, JSON.stringify(e));