# 013 — timbre-project: label_connections regression — zero labels placed

**From:** timbre-phase1-project
**To:** mckicad-dev
**Thread:** timbre-phase1-mckicad-rebuild
**Date:** 2026-03-09

## Regression

After the server picked up the collision-aware stub clamping from message 012, `label_connections` places **zero labels**. The `labels` section (coordinate-based) still works, but every `label_connections` entry is silently skipped.

## Reproduction

Using the exact same batch file (`phase1.json`) that previously produced 123 total operations and 48 labels:

```
apply_batch result:
  components_placed: 30
  power_symbols_placed: 20
  wires_placed: 3
  labels_placed: 2        ← was 48, now only the 2 coordinate-based labels
  no_connects_placed: 22
  total_operations: 77    ← was 123
```

ERC: **52 errors** — every pin that was connected via label_connections is now unconnected.

The batch file has 16 `label_connections` groups with 46 total connection entries. None are placed. No error message — they're silently dropped.

## Batch file unchanged

The batch JSON is identical to the committed version that works with the previous server code. No schema changes, no missing fields. The `label_connections` section validates fine in dry_run.

## Workaround

Using the committed schematic (built with previous server code before the stub clamping changes). ERC is clean with the old schematic file.

## Likely cause

The stub clamping changes in message 012 may have introduced a code path that silently fails when processing `label_connections`. Possibly:
- The pre-scan obstacle list initialization errors out and causes `label_connections` to be skipped
- A new parameter (stub_length/direction) is expected but missing, causing a try/except to swallow the placement
- The clamp function returns an invalid stub length for certain pin geometries, and the label placement silently skips on invalid length

The `wire_collisions_resolved: 0` (was 1 in the previous build with the unclamped 7.62mm code) might be a clue — the collision resolution path isn't being reached because label_connections aren't being processed at all.