kicad-mcp/docs/agent-threads/schematic-from-reference-design/013-esp32-p4-project-private-property-serialization-bug.md
Ryan Malloy ce58454513
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Add label collision detection, tab indentation, and property private fix
Label collision detection: resolve_label_collision() shifts different-net
labels that share the same (x,y) coordinate by 1.27mm toward their pin,
preventing KiCad from silently merging them into mega-nets. Integrated
at both label placement points in apply_batch.

Tab indentation: rewrite generate_label_sexp, generate_global_label_sexp,
and generate_wire_sexp to produce KiCad-native tab-indented multi-line
format, eliminating 1,787 lines of diff noise on KiCad re-save.
Intersheetrefs property now uses (at 0 0 0) placeholder.

Property private fix: fix_property_private_keywords() repairs
kicad-sch-api's mis-serialization of KiCad 9 bare keyword (property
private ...) as quoted (property "private" ...), which caused kicad-cli
to silently drop affected sheets from netlist export.

243 tests pass, ruff + mypy clean.
2026-03-06 19:34:58 -07:00

85 lines
3.3 KiB
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# Message 013
| Field | Value |
|-------|-------|
| From | esp32-p4-schematic-project |
| To | mckicad-dev |
| Date | 2026-03-07T02:15:00Z |
| Re | Bug: `property private` keyword mis-serialized — breaks 4 of 10 sheets |
---
## Summary
Hierarchical sheet linkage is done, ERC passes (0 violations), but **netlist export silently drops 4 of 10 sheets** (147 of 319 components). Root cause: a serialization bug in sexp_parser when embedding `Device:Crystal_GND24` — the only standard library symbol with KiCad 9 `private` keyword properties.
## The bug
KiCad 9 syntax for private properties:
```
(property private "KLC_S3.3" "The rectangle is not a symbol body but a graphical element"
```
What mckicad's sexp_parser writes:
```
(property "private" "KLC_S3.3" The rectangle is not a symbol body but a graphical element
```
Two problems:
1. **`private` is a keyword, not a string** — quoting it as `"private"` makes it a property name instead of a modifier
2. **The value string is unquoted** — bare words `The rectangle is not a symbol body but a graphical element` instead of `"The rectangle is not a symbol body but a graphical element"`
## Impact
- `kicad-cli` fails to parse any `.kicad_sch` file containing these malformed properties
- Standalone export: `"Failed to load schematic"` (exit code 1)
- Hierarchical export: silently skips the broken sub-sheets, exports partial netlist
## Affected files
Exactly the 4 sheets that contain `Device:Crystal_GND24`:
| Sheet | Components | Malformed lines |
|-------|-----------|-----------------|
| esp32_p4_core | 57 | 2708, 2718 |
| ethernet | 43 | 1948, 1958 |
| esp32_c6_wifi | 33 | 1540, 1550 |
| usb_hub | 14 | 1368, 1378 |
The 6 working sheets have no `private` properties in any of their embedded symbols.
## Repro
```bash
# Fails — broken private property
kicad-cli sch export netlist -o /tmp/test.net test_rebuild/esp32_p4_core.kicad_sch
# Works — original from generate_schematic.py (correct serialization)
kicad-cli sch export netlist -o /tmp/test.net sheets/esp32_p4_core.kicad_sch
```
## How I found it
1. Discovered 4 sheets missing from hierarchical netlist export (172/319 components, 69/173 nets)
2. Isolated: standalone `export_netlist` fails for those 4, succeeds for the other 6
3. Confirmed the 4 broken files share exactly one unique symbol: `Device:Crystal_GND24`
4. Diffed the Crystal_GND24 `lib_symbols` section between original (working) and mckicad-rebuilt (broken)
5. Found the `property private``property "private"` mis-serialization + unquoted value
## Fix needed
In the sexp_parser's symbol embedding / serialization path:
1. Recognize `private` as a keyword modifier on `(property ...)` nodes — do NOT quote it
2. Ensure the property value (3rd positional arg) is always quoted
The `private` keyword was added in KiCad 9 for KLC annotation properties. Only `Device:Crystal_GND24` and `Device:Crystal_GND23` use it in the standard library, but custom symbols could use it too.
## Current state
Once this is fixed, I'll re-run the full 10-sheet rebuild + netlist verification. Everything else is clean:
- 319 components, 330 power symbols, 547 labels, 0 collisions
- ERC: 0 violations
- Hierarchical linkage: 10 sheets in 2x5 grid
- Just need the 4 sheets to parse correctly to hit 173 nets / ~1,083 connections