splitOversized can break dependency-linked groups

[Iron-Ham]

Problem

pipeline.splitOversized (in internal/pipeline/decompose.go) naively chunks groups by position when they exceed MaxTeamSize. It does not consider dependency edges, so it can place dependent tasks in different chunks — creating separate teams with unsatisfiable cross-team dependencies.

This is the exact same class of bug fixed in #697 (cross-team dependency deadlock). The fix in #697 unions tasks along DependsOn edges, which makes large dependency-connected groups more likely to form, increasing the probability of hitting this splitOversized path.

Current risk

Low — MaxTeamSize defaults to 0 (disabled). Only affects users who explicitly configure it.

Proposed fixes

Options (pick one):

1. Make splitOversized dependency-aware — refuse to split across dependency edges
2. Skip splitting for groups that contain internal dependencies
3. Re-run union-find after splitting to detect and re-merge broken dependency chains

Context

Discovered during deep review of #697. Flagged by 5 of 10 review agents.

Files

• internal/pipeline/decompose.go:146-162 (splitOversized function)