feat(understand): room frames, the nearest panel and possible packages — what the field test asked for

The takeoffs were run again on a real P&ID pair (kept outside the repository)
and compared with the hand-made workbooks. The user chose how three gaps
should close:

- Rooms drawn as frames. A room label that no wall face holds takes the
  smallest closed, straight-sided polyline around it, provided it holds no
  other room number and is at least ten label heights a side (label+frame,
  0.8). A P&ID draws its rooms this way, so P&ID lengths are now cut at the
  frames rather than sent to the nearest label. An unnumbered mention inside
  a frame ('hot room') does not deny it.
- The nearest panel, flagged. cable_takeoff(panel_rule="nearest") is the
  default: a load that no callout places takes the nearest panel on the
  layout, among names with a panel prefix (is_panel_name: CP, JB, DB,
  MCC ...) or names a callout gives. The row is flagged panel_inferred, and
  an inferred panel never makes a package. panel_rule="stated" keeps the old
  behaviour. The takeoff_roundtrip gate and the cable correctness check read
  stated panels only: a guess is no evidence.
- Possible packages and detail copies. pipe_takeoff reports detail_copies:
  compact groups of tags drawn twice (repeated), and compact groups of one
  equipment's own parts, such as M150B, M150C and M150D of M150 (family). A
  vendor package or an equipment detail shows up this way. Nothing is
  removed until exclude_regions names a region. The runs left out go to the
  control rows as excluded_region and to excluded_m. The workbook's method
  sheet names the regions.

Each change has a synthetic test that failed first. Suite: 4986 passed, 1
xfailed. The inventory and the document numbers match (README: 4987
collected).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FKFStjEFzpGyLq5bMpWxTd

engineering/understand/draw.py

@@ -16,6 +16,7 @@ from engineering.understand.network import build_network
 from engineering.understand.report import check_lang, write_workbook
 from engineering.understand.snapshot import take_snapshot
 from engineering.understand.takeoff import (
+    PANEL_RULES,
     cable_rows,
     check_allowance,
     check_pipe_options,
@@ -51,6 +52,7 @@ async def run_pipe_takeoff(
     force: bool = False,
     layers=None,
     tol: float | None = None,
+    exclude_regions=None,
 ) -> dict:
     """`pipe_rows` over a P&ID and an optional layout, plus the workbook when `output` is named.
 
@@ -85,6 +87,7 @@ async def run_pipe_takeoff(
             vertical_allowance=options["vertical_allowance"],
             length_source=options["length_source"],
             force=bool(force),
+            exclude_regions=tuple(exclude_regions or ()),
         )
 
     result = await asyncio.to_thread(compute)
@@ -105,15 +108,25 @@ async def run_cable_takeoff(
     lang: str = "en",
     allowance: float = 0.20,
     section_rules=None,
+    panel_rule: str = "nearest",
 ) -> dict:
     """`cable_rows` over a P&ID and an optional layout, plus the workbook when `output` is named."""
     check_lang(lang)
     allowance = check_allowance(allowance)
     rules = check_section_rules(section_rules)
+    if panel_rule not in PANEL_RULES:
+        raise ValueError(
+            f"panel_rule: {panel_rule!r} unknown; choose from {', '.join(PANEL_RULES)}"
+        )
     pid = await take_snapshot(backend, pid_path)
     layout = await take_snapshot(backend, layout_path) if layout_path else None
     result = await asyncio.to_thread(
-        cable_rows, pid, layout, allowance=allowance, section_rules=list(rules) or None
+        cable_rows,
+        pid,
+        layout,
+        allowance=allowance,
+        section_rules=list(rules) or None,
+        panel_rule=panel_rule,
     )
     result["files"] = (
         await asyncio.to_thread(write_workbook, result, kind="cable", lang=lang, path=output)