Add v5.0.6 release notes

RELEASE-NOTES.md

@@ -1,5 +1,26 @@
 # Superpowers Release Notes
 
+## v5.0.6 (2026-03-24)
+
+### Inline Self-Review Replaces Subagent Review Loops
+
+The subagent review loop (dispatching a fresh agent to review plans/specs) doubled execution time (~25 min overhead) without measurably improving plan quality. Regression testing across 5 versions with 5 trials each showed identical quality scores regardless of whether the review loop ran.
+
+- **brainstorming** — replaced Spec Review Loop (subagent dispatch + 3-iteration cap) with inline Spec Self-Review checklist: placeholder scan, internal consistency, scope check, ambiguity check
+- **writing-plans** — replaced Plan Review Loop (subagent dispatch + 3-iteration cap) with inline Self-Review checklist: spec coverage, placeholder scan, type consistency
+- **writing-plans** — added explicit "No Placeholders" section defining plan failures (TBD, vague descriptions, undefined references, "similar to Task N")
+- Self-review catches 3-5 real bugs per run in ~30s instead of ~25 min, with comparable defect rates to the subagent approach
+
+### Bug Fixes
+
+- **writing-skills** — corrected false claim that SKILL.md frontmatter supports "only two fields"; now says "two required fields" and links to the agentskills.io specification for all supported fields (PR #882 by @arittr)
+
+### Codex App Compatibility
+
+- **codex-tools** — added named agent dispatch mapping documenting how to translate Claude Code's named agent types to Codex's `spawn_agent` with worker roles (PR #647 by @arittr)
+- **codex-tools** — added environment detection and Codex App finishing sections for worktree-aware skills (by @arittr)
+- **Design spec** — added Codex App compatibility design spec (PRI-823) covering read-only environment detection, worktree-safe skill behavior, and sandbox fallback patterns (by @arittr)
+
 ## v5.0.5 (2026-03-17)
 
 ### Bug Fixes