test(examples): TH-141 to template model — exports/*.typ + manifest v2 (WU-E')

Acceptance fixture for ADR-0011's template build model. TH-141 gains
exports/student.typ + exports/teacher.typ (the framework default templates,
copied from render/templates/ — these should be auto-seeded at project creation,
out of scope this round). manifest.toml [targets.*] converted to v2: artifact =
{type="single-file", filepath} + a typst-compile step naming the template;
numbering removed (it now lives in the template).

Verified end-to-end through the new path (template compiled as main + augmented
manifest, no generated driver): `cph check` → 0 errors/0 warnings; `cph build`
student → 9pp PDF, teacher → 12pp PDF; numbering correct (一、 / 2.1 / 2.2, zero
"二、一"); real content rendered.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

examples/TH-141/exports/student.typ

@@ -0,0 +1,79 @@
+// DEFAULT STUDENT TEMPLATE (framework default; ADR-0011).
+//
+// This is a *real, editable* file that lives in an engineering file at
+// `exports/student.typ`. The framework compiles it AS THE MAIN FILE with the
+// manifest injected:
+//   typst compile --root <eng-root> --input manifest=<path-rel-to-root> exports/student.typ <out>
+//
+// It is intentionally self-contained (no shared helper import) so it can be
+// copied verbatim into a new engineering file's `exports/`. Presentation —
+// heading numbering — lives HERE (editable per engineering file), not in the
+// manifest and not hardcoded in the cph-render package.
+//
+// WHY THE INCLUDE LOOP IS HERE AND NOT IN cph-render: typst resolves a dynamic
+// `include` path relative to the file it lexically appears in, and a package has
+// its own virtual root — an include inside cph-render would resolve against the
+// PACKAGE, not the engineering root. A `/<part.path>/<field>.typ` written HERE
+// (this template lives under `--root`) resolves against `--root`. So the
+// template loads content and hands cph-render an already-assembled `parts` array.
+//
+// OPEN CONTRACT POINT — optional-content presence. typst has no "does this file
+// exist" primitive (a missing `include` is a hard compile error). So the
+// template CANNOT probe disk the way the old Rust driver did for lemma `proof`.
+// It relies on the manifest declaring which optional content fields are present,
+// via a per-part `fields` array listing the content fields that exist on disk
+// (the engine knows this — it walks the part dir). Required fields are loaded
+// unconditionally; optional fields load only if listed in `fields`. If a part
+// omits `fields`, optional content is skipped (conservative). The exact shape of
+// this declaration is for the manifest/Rust contract to pin.
+
+#import "@local/cph-render:0.1.0": render-lesson, part-fields, default-heading-numbering
+
+// This template IS the student build, so the target is fixed.
+#let target = "student"
+
+// Read the injected manifest (a path string relative to typst --root).
+#let manifest = toml(sys.inputs.manifest)
+#let info = manifest.at("info", default: (:))
+#let raw-parts = manifest.at("parts", default: ())
+
+// Assemble each part: include its content fields (computed absolute paths,
+// resolved against --root) and read scalar fields from <path>/element.toml.
+// `part-fields` (from cph-render) is the single source of truth for kind->fields.
+#let parts = raw-parts.map(raw => {
+  let kind = raw.at("kind", default: none)
+  let path = raw.at("path", default: none)
+  let spec = part-fields.at(kind, default: (content: (), optional-content: (), scalars: ()))
+  // Which optional content fields are present on disk (manifest-declared).
+  let present = raw.at("fields", default: ())
+  let part = (kind: kind)
+
+  // Required content fields: <path>/<field>.typ (absolute, root-relative).
+  for field in spec.content {
+    part.insert(field, include "/" + path + "/" + field + ".typ")
+  }
+  // Optional content fields: only when the manifest says the file exists.
+  for field in spec.optional-content {
+    if field in present {
+      part.insert(field, include "/" + path + "/" + field + ".typ")
+    }
+  }
+  // Scalar fields come from <path>/element.toml.
+  if spec.scalars.len() > 0 {
+    let element = toml("/" + path + "/element.toml")
+    for field in spec.scalars {
+      let v = element.at(field, default: none)
+      if v != none and v != "" { part.insert(field, v) }
+    }
+  }
+  part
+})
+
+// Presentation: per-level heading numbering. Default (一、 / 1.1 / 1.1.1) comes
+// from cph-render; override here per engineering file if desired.
+#render-lesson(
+  info: info,
+  target: target,
+  parts: parts,
+  heading-numbering: default-heading-numbering,
+)

examples/TH-141/exports/teacher.typ

@@ -0,0 +1,62 @@
+// DEFAULT TEACHER TEMPLATE (framework default; ADR-0011).
+//
+// Lives in an engineering file at `exports/teacher.typ`. Compiled AS MAIN with
+// the manifest injected:
+//   typst compile --root <eng-root> --input manifest=<path-rel-to-root> exports/teacher.typ <out>
+//
+// Self-contained (copyable into an engineering file). Identical to student.typ
+// except the fixed target is "teacher" (so the (kind x target) render matrix in
+// cph-render shows solutions and proofs). See student.typ for the full notes on
+// why the include loop lives here (package virtual-root resolution) and on the
+// OPEN optional-content (`fields`) contract point.
+
+#import "@local/cph-render:0.1.0": render-lesson, part-fields, default-heading-numbering
+
+// This template IS the teacher build, so the target is fixed.
+#let target = "teacher"
+
+// Read the injected manifest (a path string relative to typst --root).
+#let manifest = toml(sys.inputs.manifest)
+#let info = manifest.at("info", default: (:))
+#let raw-parts = manifest.at("parts", default: ())
+
+// Assemble each part: include its content fields (computed absolute paths,
+// resolved against --root) and read scalar fields from <path>/element.toml.
+// `part-fields` (from cph-render) is the single source of truth for kind->fields.
+#let parts = raw-parts.map(raw => {
+  let kind = raw.at("kind", default: none)
+  let path = raw.at("path", default: none)
+  let spec = part-fields.at(kind, default: (content: (), optional-content: (), scalars: ()))
+  // Which optional content fields are present on disk (manifest-declared).
+  let present = raw.at("fields", default: ())
+  let part = (kind: kind)
+
+  // Required content fields: <path>/<field>.typ (absolute, root-relative).
+  for field in spec.content {
+    part.insert(field, include "/" + path + "/" + field + ".typ")
+  }
+  // Optional content fields: only when the manifest says the file exists.
+  for field in spec.optional-content {
+    if field in present {
+      part.insert(field, include "/" + path + "/" + field + ".typ")
+    }
+  }
+  // Scalar fields come from <path>/element.toml.
+  if spec.scalars.len() > 0 {
+    let element = toml("/" + path + "/element.toml")
+    for field in spec.scalars {
+      let v = element.at(field, default: none)
+      if v != none and v != "" { part.insert(field, v) }
+    }
+  }
+  part
+})
+
+// Presentation: per-level heading numbering. Default (一、 / 1.1 / 1.1.1) comes
+// from cph-render; override here per engineering file if desired.
+#render-lesson(
+  info: info,
+  target: target,
+  parts: parts,
+  heading-numbering: default-heading-numbering,
+)

examples/TH-141/manifest.toml

@@ -162,16 +162,20 @@ path = "segments/各模型对水的预测对照"
 kind = "segment"
 path = "segments/算不准背后的真实物理"
 
-# Export targets (ADR-0009): each is a build producing a typed artifact, with
-# file-resident presentation config that overrides the framework defaults.
-# Heading numbering is given explicitly per level (level-1 一、, level-2 1.1,
-# level-3 1.1.1) — overriding the render package's default via the in-file path.
+# Export targets (ADR-0009/0011): each target is a build producing a typed
+# artifact, run as an ordered list of typed steps. A `typst-compile` step names a
+# real template file under `exports/` — the framework compiles it as the main
+# file with the manifest injected, and the template reads the manifest and renders
+# the lesson. Presentation (heading numbering, styling) lives in the template
+# file, NOT here (ADR-0011 moved it off the manifest).
 [targets.student]
-artifact = "single-file"
-[targets.student.numbering]
-heading = ["{1:一}、", "{1:1}.{2:1}", "{1:1}.{2:1}.{3:1}"]
+artifact = { type = "single-file", filepath = "build/student.pdf" }
+[[targets.student.steps]]
+type = "typst-compile"
+template = "exports/student.typ"
 
 [targets.teacher]
-artifact = "single-file"
-[targets.teacher.numbering]
-heading = ["{1:一}、", "{1:1}.{2:1}", "{1:1}.{2:1}.{3:1}"]
+artifact = { type = "single-file", filepath = "build/teacher.pdf" }
+[[targets.teacher.steps]]
+type = "typst-compile"
+template = "exports/teacher.typ"