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/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