implementation-pitfallslisted

# Implementation pitfalls (project-local failure catalog) Concrete past misses on this project. Each entry has: - **What went wrong** — the specific incident with commit refs - **Why it slipped review** — the mechanism that let it through - **Mitigation** — what to insert into implementer / reviewer prompts to catch it next time These are NOT generic best practices — they are this-project trap-pattern documentation derived from incidents on `main`. Read this BEFORE you start dispatching subagents or writing a fresh implementation. They are the most cost-effective additions to your subagent prompts. --- ## Pitfall 1 — Spec scope contraction (problem statement ≠ implementation section) **What went wrong**: The Phase B spec (`docs/superpowers/specs/2026-05-22-server-mode-runner-reverse-dial-design.md`) said in the **Problem** section that ALL `harness-cli` subcommands on a runner host suffer from ACL outbound block. But the **Implementation** section was titled "Phase B: Agent leg = objproto negotiated proxy" — and the implementation shipped covering only the `agent` subcommand. User caught it months later: `harness-cli ls` from inside a runner-spawned process silently failed because cli.Dial didn't check the proxy env. Fixed in commit `2365260` (moved proxy detection into `cli.DialPeerConn`, shared by every subcommand). **Why it slipped review**: The reviewer subagent compared the diff to the Implementation section only. Spec compliance was technically PASS. The Problem