tools/epro2/kicad: Phase-2 lib_symbols — render symbol bodies from SYMBOL docs

Phase 1 emit的 .kicad_sch 里组件位置 + 属性都对，但 lib_symbols 是空
stub —— KiCad 渲染时每个组件显示成红色 "?"。Phase 2 把 SYMBOL 文档
里的 PART + RECT/POLY/CIRCLE/TEXT/PIN primitives 翻成 KiCad lib symbol
块，填到 lib_symbols 里，让 KiCad 显示真正的原理图符号。

新增 tools/epro2/kicad/sym_writer.py:
  write_lib_symbol(symbol_doc) → S-expr list 形如:
    (symbol "facere:<partId>"
      (pin_numbers (hide no))
      (pin_names (offset 1.016))
      (in_bom yes) (on_board yes)
      (property "Reference" "U" ...)
      (property "Value" "<title>" ...)
      (property "Footprint" "" hide)
      (property "Datasheet" "" hide)
      (symbol "<partId>_1_1"
        (rectangle ...)        ← from RECT.dotX1/Y1/dotX2/Y2
        (polyline (pts ...))   ← from POLY.points + closed → fill
        (circle ...)            ← from CIRCLE.center/radius
        (text "..." ...)        ← from TEXT.value/x/y/rotation
        (pin <type> line (at ...) (length ...) (name ...) (number ...))
                                ← from PIN + sibling ATTR ops
      ))

PIN 名字/编号/电气类型解析（这是关键数据探测点）：
  EPRO2 PIN 不直接带 number/name/type 字段；这些信息存为独立 ATTR 操作
  (parentId=<pin_id>, key="Pin Name"/"Pin Number"/"Pin Type")
  Pin Type 取值映射：IN→input, OUT→output, BIDIR→bidirectional,
  POWER_IN→power_in, POWER_OUT→power_out, NC→no_connect, ...
  默认 passive（保守）

sch_writer 集成（lib_symbols 自动填）：
  write_sch_page(doc, project_relations=pr) — 增 pr 可选参数
  内部 _build_lib_symbols(): 收集本 sheet 用到的 partIds → 通过
  ProjectRelations.parts_by_id 解析到 SYMBOL 文档 → write_lib_symbol →
  组装 (lib_symbols ...) 块；同 partId 多 SYMBOL 候选取第一个，去重
  WriteStats 增 lib_symbols_embedded / lib_symbols_missing

CLI 加 --no-lib-symbols 用于回到 Phase-1 行为（占位符调试用）。

ESP-VoCat 重导出验证：9/9 SCH_PAGE 全部 0 lib_miss
  P1_45092758.kicad_sch    wires=187 symbols=138 lib_emb=29
  codec_0b0163fa.kicad_sch wires=190 symbols=112 lib_emb=20
  Interface_b336a7c7.kicad_sch        symbols=95  lib_emb=13
  ...
  P1_408c9f4f.kicad_sch    wires=  6 symbols= 10 lib_emb= 3

测试：6 个新单测覆盖 outer wrapper / pin ATTR pull / 多形状 primitives /
sch_writer 集成路径 / 缺失 lib 计数 / no-pr 回退到 Phase 1。
合计 **39/39 通过**（parser 6 + relations 9 + project_relations 6 +
sexpr 6 + sch_writer 6 + sym_writer 6）。

下一步 Phase 3：footprint library + .kicad_pcb 导出。

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tools/epro2/kicad/__init__.py

@@ -16,5 +16,6 @@ mm. Conversion factor ``MIL_TO_MM = 0.0254`` is applied at writer level.
 
 from .sch_writer import write_sch_page  # noqa: F401
 from .sexpr import Sym, to_sexpr  # noqa: F401
+from .sym_writer import write_lib_symbol  # noqa: F401
 
-__all__ = ["Sym", "to_sexpr", "write_sch_page"]
+__all__ = ["Sym", "to_sexpr", "write_sch_page", "write_lib_symbol"]

tools/epro2/kicad/__main__.py

@@ -15,6 +15,7 @@ import re
 import sys
 from pathlib import Path
 
+from ..project_relations import ProjectRelations
 from ..replay import Project, replay_project
 from .sch_writer import write_sch_page
 
@@ -27,7 +28,12 @@ def _safe_filename(s: str) -> str:
     return s or "untitled"
 
 
-def _convert_one(proj: Project, doc_uuid: str, out_dir: Path) -> Path:
+def _convert_one(
+    proj: Project,
+    doc_uuid: str,
+    out_dir: Path,
+    pr: ProjectRelations | None = None,
+) -> Path:
     if doc_uuid not in proj.documents:
         candidates = [u for u in proj.documents if u.startswith(doc_uuid)]
         if len(candidates) != 1:
@@ -37,7 +43,7 @@ def _convert_one(proj: Project, doc_uuid: str, out_dir: Path) -> Path:
     if doc.doc_type != "SCH_PAGE":
         raise SystemExit(f"doc {doc_uuid} is {doc.doc_type!r}, not SCH_PAGE")
 
-    text = write_sch_page(doc)
+    text = write_sch_page(doc, project_relations=pr)
     title = (doc.objects.get("META") or {}).get("title") or doc_uuid[:12]
     out_path = out_dir / f"{_safe_filename(title)}_{doc_uuid[:8]}.kicad_sch"
     out_path.write_text(text, encoding="utf-8")
@@ -46,6 +52,7 @@ def _convert_one(proj: Project, doc_uuid: str, out_dir: Path) -> Path:
         print(
             f"  {out_path.name}: wires={stats.wires} symbols={stats.symbol_placements} "
             f"text={stats.text} skipped={stats.skipped} "
+            f"lib_emb={stats.lib_symbols_embedded} lib_miss={stats.lib_symbols_missing}"
         )
     return out_path
 
@@ -57,13 +64,19 @@ def main(argv: list[str] | None = None) -> int:
     g.add_argument("--doc", help="SCH_PAGE doc uuid (or unique prefix) to convert")
     g.add_argument("--all-sch", action="store_true", help="convert every SCH_PAGE")
     ap.add_argument("--out", type=Path, default=Path("data/processed/kicad_sch"))
+    ap.add_argument(
+        "--no-lib-symbols",
+        action="store_true",
+        help="skip lib_symbols generation (Phase 1 mode — placements only, red ?)",
+    )
     args = ap.parse_args(argv)
 
     proj = replay_project(args.project_dir)
     args.out.mkdir(parents=True, exist_ok=True)
+    pr = None if args.no_lib_symbols else ProjectRelations.build(proj)
 
     if args.doc:
-        _convert_one(proj, args.doc, args.out)
+        _convert_one(proj, args.doc, args.out, pr=pr)
         return 0
 
     targets = [u for u, d in proj.documents.items() if d.doc_type == "SCH_PAGE"]
@@ -73,7 +86,7 @@ def main(argv: list[str] | None = None) -> int:
     print(f"Converting {len(targets)} SCH_PAGE docs → {args.out}")
     for u in targets:
         try:
-            _convert_one(proj, u, args.out)
+            _convert_one(proj, u, args.out, pr=pr)
         except Exception as e:  # noqa: BLE001
             print(f"  FAIL {u[:12]}: {e}", file=sys.stderr)
     return 0

tools/epro2/kicad/sch_writer.py

@@ -19,6 +19,7 @@ import math
 import uuid as _uuid
 from dataclasses import dataclass
 
+from ..project_relations import ProjectRelations
 from ..relations import Relations
 from ..replay import Document
 from .sexpr import Sym, to_sexpr
@@ -41,6 +42,8 @@ class WriteStats:
     symbol_placements: int = 0
     text: int = 0
     skipped: int = 0
+    lib_symbols_embedded: int = 0
+    lib_symbols_missing: int = 0
 
 
 def _new_uuid() -> str:
@@ -66,11 +69,18 @@ def write_sch_page(
     *,
     title: str | None = None,
     sheet_origin_mm: tuple[float, float] = (25.4, 25.4),
+    project_relations: ProjectRelations | None = None,
 ) -> str:
     """Render a single SCH_PAGE Document as kicad_sch text.
 
     ``sheet_origin_mm`` is added to every coordinate so the schematic doesn't
     sit at (0,0) (KiCad's title block lives there). Default 1 inch margin.
+
+    When ``project_relations`` is given, the ``lib_symbols`` block is
+    populated by resolving each placement's ``partId`` to the SYMBOL doc(s)
+    hosting that PART; the body of the first matching SYMBOL is rendered via
+    :func:`sym_writer.write_lib_symbol`. If a partId can't be resolved, we
+    still emit the placement (KiCad shows a red ``?``).
     """
     if doc.doc_type != "SCH_PAGE":
         raise ValueError(f"expected SCH_PAGE doc, got {doc.doc_type!r}")
@@ -165,6 +175,10 @@ def write_sch_page(
         or doc.doc_uuid[:12]
     )
 
+    # Populate lib_symbols block from used partIds (Phase 2).
+    lib_symbols = _build_lib_symbols(rel, project_relations, stats) \
+        if project_relations is not None else [Sym("lib_symbols")]
+
     sch: list = [
         Sym("kicad_sch"),
         [Sym("version"), KICAD_SCH_VERSION],
@@ -175,7 +189,7 @@ def write_sch_page(
             [Sym("title"), sch_title],
             [Sym("comment"), 1, f"epro2 doc_uuid: {doc.doc_uuid}"],
             [Sym("comment"), 2, f"editor: {doc.head.get('editVersion','')}"]],
-        [Sym("lib_symbols")],  # empty for Phase 1; Phase 2 will populate
+        lib_symbols,
         *elements,
         [Sym("sheet_instances"),
             [Sym("path"), "/", [Sym("page"), "1"]]],
@@ -184,3 +198,46 @@ def write_sch_page(
     # Stash stats on the function for tests / CLI to inspect.
     write_sch_page.last_stats = stats  # type: ignore[attr-defined]
     return to_sexpr(sch, pretty=True)
+
+
+def _build_lib_symbols(
+    sch_rel: Relations,
+    pr: ProjectRelations,
+    stats: WriteStats,
+) -> list:
+    """Resolve every COMPONENT.partId on this sheet to a SYMBOL doc and
+    embed its body in the ``(lib_symbols ...)`` block.
+
+    Returns the full ``[Sym("lib_symbols"), <symbol entry>, ...]`` list.
+    """
+    from .sym_writer import write_lib_symbol  # local to avoid cycle
+
+    used_part_ids: set[str] = set()
+    for cid, comp in sch_rel.components.items():
+        pid = comp.get("partId")
+        if pid:
+            used_part_ids.add(str(pid))
+
+    block: list = [Sym("lib_symbols")]
+    seen_emitted: set[str] = set()
+    for pid in sorted(used_part_ids):
+        sym_docs = pr.parts_by_id.get(pid, [])
+        if not sym_docs:
+            stats.lib_symbols_missing += 1
+            continue
+        # Use first SYMBOL doc. Skip if same partId already emitted (dedupe).
+        if pid in seen_emitted:
+            continue
+        sym_doc = pr.project.documents.get(sym_docs[0])
+        if not sym_doc:
+            stats.lib_symbols_missing += 1
+            continue
+        entry = write_lib_symbol(sym_doc)
+        if entry is None:
+            stats.lib_symbols_missing += 1
+            continue
+        block.append(entry)
+        seen_emitted.add(pid)
+        stats.lib_symbols_embedded += 1
+
+    return block

tools/epro2/kicad/sym_writer.py

@@ -0,0 +1,179 @@
+"""Convert one EPRO2 SYMBOL Document → a KiCad ``(symbol ...)`` lib entry.
+
+Phase-2 scope: render the SYMBOL primitives so KiCad's lib_symbols block can
+provide a real graphical body for each placement (vs the Phase-1 red ``?``).
+
+Coverage / fidelity:
+  - PART        → outer (symbol "facere:<partId>" ...) wrapper + properties
+  - PIN + ATTR  → (pin <type> line (at x y rot) (length L) (name ...) (number ...))
+                  with ATTR(parent=pin, key="Pin Name"/"Pin Number"/"Pin Type")
+                  pulled from sibling ATTR ops
+  - RECT        → (rectangle (start ...) (end ...) ...)
+  - POLY        → (polyline (pts (xy ...) ...) ...) with closed→fill
+  - CIRCLE      → (circle (center ...) (radius ...) ...)
+  - TEXT        → (text "..." (at ...) ...)
+  - ATTR (no parent / on PART) → contributes to symbol-level Reference/Value/...
+                                  (best-effort; mostly ignored at body level)
+
+Coordinate convention:
+  EPRO2 SYMBOL primitives use **mil** (same as schematic); we convert via
+  ``MIL_TO_MM = 0.0254``. KiCad lib symbol coords are **Y-up** internally,
+  but the placement of pins relative to body origin is what matters; for
+  ESP-VoCat the empirical Y orientation is consistent (pins on left at -X,
+  pins on right at +X), so we do not flip Y. If KiCad renders flipped, the
+  fix is a per-axis sign in ``_pt`` here.
+"""
+
+from __future__ import annotations
+
+from ..relations import Relations
+from ..replay import Document
+from .sch_writer import MIL_TO_MM
+from .sexpr import Sym
+
+# EPRO2 Pin Type -> KiCad electrical type. Empirical mapping; defaults to passive.
+PIN_TYPE_MAP: dict[str, str] = {
+    "IN": "input",
+    "OUT": "output",
+    "BIDIR": "bidirectional",
+    "BIDIRECTIONAL": "bidirectional",
+    "TRI_STATE": "tri_state",
+    "TRISTATE": "tri_state",
+    "PASSIVE": "passive",
+    "POWER_IN": "power_in",
+    "POWER_OUT": "power_out",
+    "OPEN_COLLECTOR": "open_collector",
+    "OPEN_EMITTER": "open_emitter",
+    "NC": "no_connect",
+    "NOT_CONNECTED": "no_connect",
+    "UNSPECIFIED": "unspecified",
+}
+
+
+def _pt(v) -> float:
+    """Coerce a mil number to mm. None → 0.0."""
+    if v is None:
+        return 0.0
+    try:
+        return float(v) * MIL_TO_MM
+    except (TypeError, ValueError):
+        return 0.0
+
+
+def _stroke(width: float = 0.254) -> list:
+    return [Sym("stroke"), [Sym("width"), width], [Sym("type"), Sym("default")]]
+
+
+def _fill(kind: str = "none") -> list:
+    return [Sym("fill"), [Sym("type"), Sym(kind)]]
+
+
+def _font(size: float = 1.27) -> list:
+    return [Sym("effects"), [Sym("font"), [Sym("size"), size, size]]]
+
+
+def _hidden_font(size: float = 1.27) -> list:
+    return [Sym("effects"), [Sym("font"), [Sym("size"), size, size]],
+            [Sym("hide"), Sym("yes")]]
+
+
+def _property(name: str, value: str, idx: int, *, hide: bool = False) -> list:
+    return [
+        Sym("property"), name, value,
+        [Sym("at"), 0, 0, 0],
+        _hidden_font() if hide else _font(),
+    ]
+
+
+def write_lib_symbol(doc: Document, *, lib_prefix: str = "facere") -> list | None:
+    """Render a SYMBOL Document as a KiCad ``(symbol ...)`` block (S-expr list).
+
+    Returns ``None`` if the doc has no PART (malformed lib doc). The caller
+    embeds the returned list into a parent ``(lib_symbols ...)`` container.
+    """
+    if doc.doc_type != "SYMBOL":
+        return None
+
+    rel = Relations.build(doc)
+    if not rel.parts:
+        return None
+
+    # Pick the first PART (ESP-VoCat probe shows 1 PART per SYMBOL doc).
+    part_id, part = next(iter(rel.parts.items()))
+    title = str(part.get("title") or part_id)
+
+    # Body primitives: RECT, POLY, CIRCLE, TEXT, PIN.
+    body: list = [Sym("symbol"), f"{part_id}_1_1"]
+    for oid, obj in doc.objects.items():
+        t = obj.get("_type")
+        # Filter to primitives owned by this part (ignore stray objects)
+        if obj.get("partId") != part_id:
+            continue
+        if t == "RECT":
+            x1, y1 = _pt(obj.get("dotX1")), _pt(obj.get("dotY1"))
+            x2, y2 = _pt(obj.get("dotX2")), _pt(obj.get("dotY2"))
+            body.append([
+                Sym("rectangle"),
+                [Sym("start"), x1, y1],
+                [Sym("end"), x2, y2],
+                _stroke(),
+                _fill(),
+            ])
+        elif t == "POLY":
+            pts = obj.get("points") or []
+            xy_list = [Sym("pts")] + [
+                [Sym("xy"), _pt(p.get("x")), _pt(p.get("y"))] for p in pts
+                if isinstance(p, dict)
+            ]
+            if len(xy_list) >= 3:  # at least 2 points + the "pts" tag
+                body.append([
+                    Sym("polyline"),
+                    xy_list,
+                    _stroke(),
+                    _fill("outline" if obj.get("closed") else "none"),
+                ])
+        elif t == "CIRCLE":
+            body.append([
+                Sym("circle"),
+                [Sym("center"), _pt(obj.get("centerX")), _pt(obj.get("centerY"))],
+                [Sym("radius"), _pt(obj.get("radius"))],
+                _stroke(),
+                _fill(),
+            ])
+        elif t == "TEXT":
+            val = str(obj.get("value") or "").strip()
+            if not val:
+                continue
+            body.append([
+                Sym("text"), val,
+                [Sym("at"), _pt(obj.get("x")), _pt(obj.get("y")),
+                            float(obj.get("rotation") or 0)],
+                _font(),
+            ])
+        elif t == "PIN":
+            attrs = rel.attrs_dict(oid)
+            pin_number = str(attrs.get("Pin Number") or "")
+            pin_name = str(attrs.get("Pin Name") or "")
+            pin_type_raw = str(attrs.get("Pin Type") or "").upper()
+            elec = PIN_TYPE_MAP.get(pin_type_raw, "passive")
+            body.append([
+                Sym("pin"), Sym(elec), Sym("line"),
+                [Sym("at"), _pt(obj.get("x")), _pt(obj.get("y")),
+                            float(obj.get("rotation") or 0)],
+                [Sym("length"), _pt(obj.get("length"))],
+                [Sym("name"), pin_name or "~", _font()],
+                [Sym("number"), pin_number or "~", _font()],
+            ])
+
+    return [
+        Sym("symbol"), f"{lib_prefix}:{part_id}",
+        [Sym("pin_numbers"), [Sym("hide"), Sym("no")]],
+        [Sym("pin_names"), [Sym("offset"), 1.016]],
+        [Sym("in_bom"), Sym("yes")],
+        [Sym("on_board"), Sym("yes")],
+        _property("Reference", "U", 0),
+        _property("Value", title, 1),
+        _property("Footprint", "", 2, hide=True),
+        _property("Datasheet", "", 3, hide=True),
+        body,
+    ]

tools/epro2/tests/test_sym_writer.py

@@ -0,0 +1,126 @@
+"""Symbol writer regression: synthetic SYMBOL doc → KiCad lib symbol entry."""
+
+from tools.epro2.kicad._sexpr_reader import parse
+from tools.epro2.kicad.sch_writer import write_sch_page
+from tools.epro2.kicad.sexpr import to_sexpr
+from tools.epro2.kicad.sym_writer import write_lib_symbol
+from tools.epro2.project_relations import ProjectRelations
+from tools.epro2.replay import Document, Project
+
+
+def _sym_doc(uuid: str, part_id: str, primitives: list[tuple[str, dict]]) -> Document:
+    d = Document(doc_uuid=uuid, doc_type="SYMBOL")
+    d.objects[part_id] = {"_type": "PART", "BBOX": [-10, 10, 10, -10], "title": part_id}
+    for k, v in primitives:
+        d.objects[k] = v
+    return d
+
+
+def _block(parsed, name):
+    return [c for c in parsed if isinstance(c, list) and c and c[0] == name]
+
+
+def test_write_lib_symbol_emits_outer_wrapper_and_body():
+    d = _sym_doc("sym1", "MyPart.1", [])
+    entry = write_lib_symbol(d)
+    assert entry is not None
+    text = to_sexpr(entry)
+    p = parse(text)
+    assert p[0] == "symbol"
+    assert p[1] == "facere:MyPart.1"
+    # Properties: Reference / Value / Footprint / Datasheet
+    props = _block(p, "property")
+    by_name = {x[1]: x[2] for x in props}
+    assert by_name["Reference"] == "U"
+    assert by_name["Value"] == "MyPart.1"
+    assert by_name["Footprint"] == ""
+    # Inner body wrapper named <part>_1_1
+    inner = _block(p, "symbol")
+    assert len(inner) == 1
+    assert inner[0][1] == "MyPart.1_1_1"
+
+
+def test_pin_renders_with_attr_pulled_metadata():
+    d = _sym_doc("sym1", "MyPart.1", [
+        ("e5", {"_type": "PIN", "partId": "MyPart.1",
+                "x": -15, "y": 0, "length": 10, "rotation": 0}),
+        ("e6", {"_type": "ATTR", "parentId": "e5", "key": "Pin Name", "value": "VCC"}),
+        ("e7", {"_type": "ATTR", "parentId": "e5", "key": "Pin Number", "value": "1"}),
+        ("e8", {"_type": "ATTR", "parentId": "e5", "key": "Pin Type", "value": "POWER_IN"}),
+    ])
+    entry = write_lib_symbol(d)
+    text = to_sexpr(entry)
+    parsed = parse(text)
+    inner_body = next(c for c in parsed if isinstance(c, list) and c and c[0] == "symbol")
+    pins = [c for c in inner_body if isinstance(c, list) and c and c[0] == "pin"]
+    assert len(pins) == 1
+    pin = pins[0]
+    assert pin[1] == "power_in"     # electrical type mapped
+    assert pin[2] == "line"          # shape
+    name_block = next(c for c in pin if isinstance(c, list) and c and c[0] == "name")
+    num_block = next(c for c in pin if isinstance(c, list) and c and c[0] == "number")
+    assert name_block[1] == "VCC"
+    assert num_block[1] == "1"
+
+
+def test_rect_poly_circle_text_emit_correct_shapes():
+    d = _sym_doc("sym1", "MyPart.1", [
+        ("r1", {"_type": "RECT", "partId": "MyPart.1",
+                "dotX1": -10, "dotY1": -5, "dotX2": 10, "dotY2": 5}),
+        ("p1", {"_type": "POLY", "partId": "MyPart.1",
+                "points": [{"x": 0, "y": 0}, {"x": 5, "y": 0}, {"x": 5, "y": 5}],
+                "closed": True}),
+        ("c1", {"_type": "CIRCLE", "partId": "MyPart.1",
+                "centerX": 0, "centerY": 0, "radius": 3}),
+        ("t1", {"_type": "TEXT", "partId": "MyPart.1",
+                "x": 0, "y": -5, "value": "label"}),
+    ])
+    entry = write_lib_symbol(d)
+    parsed = parse(to_sexpr(entry))
+    inner = next(c for c in parsed if isinstance(c, list) and c[0] == "symbol")
+    types = [c[0] for c in inner if isinstance(c, list)]
+    assert "rectangle" in types
+    assert "polyline" in types
+    assert "circle" in types
+    assert "text" in types
+
+
+def test_non_symbol_doc_returns_none():
+    d = Document(doc_uuid="x", doc_type="SCH_PAGE")
+    assert write_lib_symbol(d) is None
+
+
+def test_sch_writer_embeds_lib_symbols_via_project_relations():
+    sym = _sym_doc("sym1", "MyPart.1", [
+        ("e5", {"_type": "PIN", "partId": "MyPart.1", "x": 0, "y": 0, "length": 10}),
+        ("e6", {"_type": "ATTR", "parentId": "e5", "key": "Pin Name", "value": "1"}),
+        ("e7", {"_type": "ATTR", "parentId": "e5", "key": "Pin Number", "value": "1"}),
+    ])
+    sch = Document(doc_uuid="sch1", doc_type="SCH_PAGE")
+    sch.objects["e1"] = {"_type": "COMPONENT", "partId": "MyPart.1", "x": 0, "y": 0, "rotation": 0}
+    sch.objects["e2"] = {"_type": "COMPONENT", "partId": "GhostPart.99", "x": 50, "y": 50}
+
+    p = Project(project_uuid="p")
+    p.documents["sym1"] = sym
+    p.documents["sch1"] = sch
+    pr = ProjectRelations.build(p)
+
+    text = write_sch_page(sch, project_relations=pr)
+    parsed = parse(text)
+    lib = next(c for c in parsed if isinstance(c, list) and c[0] == "lib_symbols")
+    embedded = [c for c in lib[1:] if isinstance(c, list) and c[0] == "symbol"]
+    assert len(embedded) == 1                     # MyPart found, GhostPart missed
+    assert embedded[0][1] == "facere:MyPart.1"
+    stats = getattr(write_sch_page, "last_stats")
+    assert stats.lib_symbols_embedded == 1
+    assert stats.lib_symbols_missing == 1
+
+
+def test_sch_writer_without_project_relations_emits_empty_lib_symbols():
+    sch = Document(doc_uuid="sch1", doc_type="SCH_PAGE")
+    sch.objects["e1"] = {"_type": "COMPONENT", "partId": "X.1", "x": 0, "y": 0}
+    text = write_sch_page(sch)  # no pr passed
+    parsed = parse(text)
+    lib = next(c for c in parsed if isinstance(c, list) and c[0] == "lib_symbols")
+    # Phase-1 stub: just `(lib_symbols)` with no children
+    assert lib == ["lib_symbols"]