When Agent Skills Overlap: Auditing Superpowers Against Codex Harness
Agent Skills are multiplying fast, and the default assumption that more Skills equals better engineering is breaking down. When a Skill suite silently overrides a project's branch strategy, CI gates, or source-of-truth documents, the cost is duplicated work, conflicting approvals, and governance drift that outlasts the plugin itself. The audit framework and prompts here give teams a repeatable way to cut overlap before it hardens into technical debt.
Running Superpowers alongside Codex Harness creates conflicts in how work gets planned, approved, and wrapped up, not in code execution. The overlap centers on five areas: a global Skill router that forces invocation even for simple tasks, fixed approval gates that pause every creative change regardless of risk, parallel document sources of truth that diverge from ADRs and issues, generic sub-agent and worktree orchestration that ignores project-specific branch and dependency rules, and one-size-fits-all verification that cannot substitute for lint, contract tests, or consumer canaries.
A four-layer model — Harness, Project Governance, Skill, Tool — makes the boundaries explicit. Skills that change execution order for all tasks, override existing authorization rules, or establish new long-term fact sources have crossed into Harness territory. The practical fix is a triage: keep narrow methods like systematic debugging and TDD, rewrite useful Skills whose triggers are too broad, and disable anything that duplicates Harness scheduling, approval, or branch lifecycle management.
AIHero and mattpocock/skills offer a lower-intrusion reference design: per-Skill installation, explicit vs. model-invoked distinction, and reviewable file-based Skills. Cross-Harness discovery requires placing shared Skills in `~/.agents/skills/` or the repo's `.agents/skills/`, since Cursor and Codex scan different directories. The article ships five ready-to-use audit prompts that inventory overlaps, rewrite broad Skills, decouple before plugin removal, troubleshoot discovery, and generate governance rules for AGENTS.md.
The instinct to install a comprehensive Skill suite as a quick fix for engineering discipline creates a governance debt that is harder to unwind than the original lack of process. The plugin's assumptions about branching, dependency installation, and approval gates become invisible defaults that outlive the plugin itself.
Skill intrusiveness is not about file size or count — it is about whether the Skill participates in global scheduling. A single Skill that requires invocation before every reply does more architectural damage than twenty narrowly triggered utility Skills.
The directory discovery asymmetry between Cursor and Codex (`~/.cursor/skills/` vs `~/.agents/skills/`) is a concrete interoperability gap that will produce silent failures as teams mix agents. The fix is trivial — one shared directory — but the failure mode is invisible until a Skill silently doesn't load.
Parallel document sources of truth are the hardest overlap to detect and the most expensive to fix. When architecture conclusions live in both ADRs and Skill design drafts, the repo accumulates two diverging narratives, and removing the plugin later leaves dangling references that break institutional memory.
The four-layer model (Harness → Project Governance → Skill → Tool) is a useful litmus test that generalizes beyond Superpowers and Codex: any Skill that reaches upward into Harness or sideways into Project Governance is a candidate for rewrite or removal.