diff --git a/render/examples/smoke-config.typ b/render/examples/smoke-config.typ
new file mode 100644
index 0000000..9847344
--- /dev/null
+++ b/render/examples/smoke-config.typ
@@ -0,0 +1,14 @@
+// Smoke test — exercises the per-target presentation `config` override path
+// (ADR-0009). Here the engineering-file-supplied `config.numbering.heading`
+// overrides the framework-default heading numbering. The patterns happen to
+// match the correct per-level scheme (level-1 `一、`, level-2 `1.1`), proving
+// the override is wired AND yields correct (NOT `二、一、`) output.
+#import "../lib.typ": display
+#import "smoke-parts.typ": info, parts
+
+#display(
+  info: info,
+  target: "teacher",
+  parts: parts,
+  config: (numbering: (heading: ("{1:一}、", "{1:1}.{2:1}"))),
+)
diff --git a/render/examples/smoke-parts.typ b/render/examples/smoke-parts.typ
index fec937d..2a118c1 100644
--- a/render/examples/smoke-parts.typ
+++ b/render/examples/smoke-parts.typ
@@ -8,13 +8,26 @@
 )
 
 #let parts = (
-  // segment
+  // segment — with NESTED headings so per-level numbering is visible:
+  //   level-1 `=` should render `一、`, level-2 `==` should render `1.1`
+  //   (NOT the old buggy `二、一、`).
   (
     kind: "segment",
     textbook: [
+      = 平面向量的数量积
+
       本节研究平面向量的基本运算。设 $arrow(a)$、$arrow(b)$ 为平面内两个向量，
       其数量积定义为 $arrow(a) dot arrow(b) = |arrow(a)| |arrow(b)| cos theta$，
       其中 $theta$ 为两向量的夹角。
+
+      == 坐标表示
+
+      在直角坐标系下，若 $arrow(a) = (x_1, y_1)$、$arrow(b) = (x_2, y_2)$，则
+      $arrow(a) dot arrow(b) = x_1 x_2 + y_1 y_2$。
+
+      == 几何意义
+
+      数量积等于一个向量的模与另一向量在其方向上投影之积。
     ],
   ),
   // example WITH source
diff --git a/render/lib.typ b/render/lib.typ
index 04f64e7..ac45b1d 100644
--- a/render/lib.typ
+++ b/render/lib.typ
@@ -23,7 +23,7 @@
 //             fields). Never crashes. The "no render rule => warning"
 //             diagnostic is the Rust side's job, not ours.
 
-#import "src/style.typ": base-style, title-block, subtitle-block
+#import "src/style.typ": base-style, default-heading-numbering, title-block, subtitle-block
 #import "src/elements/segment.typ": display-segment
 #import "src/elements/example.typ": display-example
 #import "src/elements/lemma.typ": display-lemma
@@ -75,17 +75,34 @@
 /// - `info`:   dict, e.g. (title: "…", author: "…"). `author` may be absent.
 /// - `target`: string. MVP: "student" | "teacher". Unknown => conservative.
 /// - `parts`:  ordered array of part dicts (see file header).
-#let display(info: (:), target: "student", parts: ()) = {
+/// - `config`: dict carrying the target's build/presentation overrides
+///             (ADR-0009). Open/forward-compatible — read keys with
+///             `.at(.., default: ..)`. Recognised keys (MVP):
+///               `config.numbering.heading`: array of per-level numbly pattern
+///                 strings, e.g. `("{1:一}、", "{1:1}.{2:1}")`. Optional; when
+///                 absent the framework default (correct per-level scheme) is
+///                 used. Future presentation knobs slot in without touching
+///                 this signature.
+#let display(info: (:), target: "student", parts: (), config: (:)) = {
   let title = info.at("title", default: [])
   let author = info.at("author", default: none)
 
+  // Resolve presentation config -> framework defaults, file may override.
+  // `config.numbering.heading` (array of numbly patterns) overrides the
+  // framework default per-level numbering when present.
+  let numbering-cfg = config.at("numbering", default: (:))
+  let heading-numbering = numbering-cfg.at(
+    "heading",
+    default: default-heading-numbering,
+  )
+
   // `document` author wants a string/array; normalise the optional field.
   set document(
     title: title,
     author: if author == none { () } else { author },
   )
 
-  show: base-style
+  show: base-style.with(heading-numbering: heading-numbering)
 
   // Reset shared counters so each rendered lesson numbers from 1.
   example-counter.update(0)
diff --git a/render/src/style.typ b/render/src/style.typ
index cb97c20..b26313f 100644
--- a/render/src/style.typ
+++ b/render/src/style.typ
@@ -1,18 +1,36 @@
 // Base document styling: CJK fonts, headings, math, paragraph layout, page.
 //
-// Zero external dependencies. Heading numbering uses builtin `numbering`
-// strings (no @preview/numbly) so the package compiles with no network.
+// Heading numbering is PER-LEVEL and built from a numbly pattern array passed
+// in by the caller (lib.typ resolves it from config + framework default). This
+// fixes the old single-pattern bug where one `numbering: "一、"` was reused for
+// every level (a level-2 heading rendered as `二、一、…`). The only @preview
+// dependency is `@preview/numbly`, vendored under `render/vendor/...` for
+// network-free CI; see render/typst.toml's note.
 
+#import "@preview/numbly:0.1.0": numbly
 #import "fonts.typ"
 
-/// Apply the base style to a document body. Used as `show: base-style`.
-#let base-style(doc) = {
+/// Framework-default per-level heading numbering patterns (numbly syntax).
+/// Level 1 -> `一、`, level 2 -> `1.1`, level 3 -> `1.1.1`. This is the
+/// correct-by-default scheme; `config.numbering.heading` overrides it.
+#let default-heading-numbering = (
+  "{1:一}、",
+  "{1:1}.{2:1}",
+  "{1:1}.{2:1}.{3:1}",
+)
+
+/// Apply the base style to a document body. Used as `show: base-style(..)`.
+///
+/// `heading-numbering` is an array of per-level numbly pattern strings; it is
+/// spread into `numbly(..)` to build the per-level heading numbering function.
+#let base-style(heading-numbering: default-heading-numbering, doc) = {
   // Language / region drive CJK line-breaking and punctuation.
   set text(lang: "zh", region: "cn", size: 12pt, font: fonts.serif)
   set text(cjk-latin-spacing: auto)
 
-  // Heading numbering: 一、 / 1.1 / 1.1.1 — builtin numbering, no deps.
-  set heading(numbering: "一、")
+  // Per-level heading numbering via numbly: each level gets its own pattern,
+  // so level 2 renders `1.1`, not the old buggy `二、一、`.
+  set heading(numbering: numbly(..heading-numbering))
   show heading: set text(font: fonts.sans)
 
   // Number display equations.
diff --git a/render/typst.toml b/render/typst.toml
index 058fabc..b45f153 100644
--- a/render/typst.toml
+++ b/render/typst.toml
@@ -6,3 +6,13 @@ compiler = "0.15.0"
 authors = ["curriculum-project-hub"]
 license = "MIT"
 description = "Curriculum lesson render package: single `display` entry over an ordered list of typed parts (segment/example/lemma/sop), targeting student/teacher handouts."
+
+# External @preview dependencies (resolved via the typst package registry):
+#   @preview/numbly:0.1.0  — per-level heading numbering (src/style.typ).
+# numbly is dependency-free (pure typst). For network-free CI the package is
+# VENDORED in-repo at:
+#   render/vendor/typst-packages/preview/numbly/0.1.0/
+# mirroring the typst preview-cache layout
+# ({cache}/typst/packages/preview/numbly/0.1.0/). Point typst's package cache /
+# resolver at render/vendor/typst-packages (e.g. TYPST_PACKAGE_CACHE_PATH or the
+# embedded World's preview dir) so `@preview/numbly:0.1.0` resolves offline.
diff --git a/render/vendor/typst-packages/preview/numbly/0.1.0/LICENSE b/render/vendor/typst-packages/preview/numbly/0.1.0/LICENSE
new file mode 100644
index 0000000..9162d3e
--- /dev/null
+++ b/render/vendor/typst-packages/preview/numbly/0.1.0/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2024 梦飞翔
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
\ No newline at end of file
diff --git a/render/vendor/typst-packages/preview/numbly/0.1.0/README.md b/render/vendor/typst-packages/preview/numbly/0.1.0/README.md
new file mode 100644
index 0000000..c8547fe
--- /dev/null
+++ b/render/vendor/typst-packages/preview/numbly/0.1.0/README.md
@@ -0,0 +1,43 @@
+# numbly
+
+A package that helps you to specify different numbering formats for different levels of headings.
+
+Suppose you want to specify the following numbering format for your document:
+
+- Appendix A. Guide
+  - A.1. Installation
+    - Step 1. Download
+    - Step 2. Install
+  - A.2. Usage
+
+You might use `if` to achieve this:
+
+```typst
+#set heading(numbering: (..nums) => {
+  nums = nums.pos()
+  if nums.len() == 1 {
+    return "Appendix " + numbering("A.", ..nums)
+  } else if nums.len() == 2 {
+    return numbering("A.1.", ..nums)
+  } else {
+    return "Step " + numbering("1.", nums.last())
+  }
+})
+
+= Guide
+== Installation
+=== Download
+=== Install
+== Usage
+```
+
+But with `numbly`, you can do this more easily:
+
+```typst
+#import "@preview/numbly:0.1.0": numbly
+#set heading(numbering: numbly(
+  "Appendix {1:A}.", // use {level:format} to specify the format
+  "{1:A}.{2}.", // if format is not specified, arabic numbers will be used
+  "Step {3}.", // here, we only want the 3rd level
+))
+```
diff --git a/render/vendor/typst-packages/preview/numbly/0.1.0/lib.typ b/render/vendor/typst-packages/preview/numbly/0.1.0/lib.typ
new file mode 100644
index 0000000..baac794
--- /dev/null
+++ b/render/vendor/typst-packages/preview/numbly/0.1.0/lib.typ
@@ -0,0 +1,31 @@
+#let numbly(..arr, default: "1.") = (..nums) => {
+  let arr = arr.pos()
+  nums = nums.pos()
+  if nums.len() > arr.len() {
+    if default == none {
+      return none
+    }
+    if type(default) == function {
+      return default(..nums)
+    }
+    return numbering(default, ..nums)
+  }
+  let format = arr.at(nums.len() - 1)
+  if format == none {
+    return none
+  }
+  if type(format) == function {
+    return format(..nums)
+  }
+  format.replace(
+    regex("\{(\d)(:(.+?))?\}"),
+    m => {
+      let (a, b, c) = m.captures
+      if b != none {
+        numbering(c, nums.at(int(a) - 1))
+      } else {
+        str(nums.at(int(a) - 1))
+      }
+    },
+  )
+}
diff --git a/render/vendor/typst-packages/preview/numbly/0.1.0/typst.toml b/render/vendor/typst-packages/preview/numbly/0.1.0/typst.toml
new file mode 100644
index 0000000..9ecc5e7
--- /dev/null
+++ b/render/vendor/typst-packages/preview/numbly/0.1.0/typst.toml
@@ -0,0 +1,10 @@
+[package]
+name = "numbly"
+version = "0.1.0"
+entrypoint = "lib.typ"
+authors = ["flaribbit <@flaribbit>"]
+license = "MIT"
+description = "A package that helps you to specify different numbering formats for different levels of headings."
+categories = ["utility"]
+keywords = ["numbering", "helper", "tool"]
+repository = "https://github.com/flaribbit/numbly"
\ No newline at end of file