release: v3.20.6 - agentskills.io integration + 4 resource evaluations

- agentskills.io open standard: frontmatter table, skills-ref CLI, portability section
- Agent Skills supply chain risks (security-hardening.md §1.2)
- anthropics/skills (60K+★) added to complementary resources
- 16 new reference.yaml entries
- Resource evaluations: agentskills.io (4/5), Skill Doctor (2/5), dclaude (new), paddo (new)
- Sandbox isolation + README updates

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/resource-evaluations/paddo-team-tips-eval.md

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+# Resource Evaluation: 10 Tips from Inside the Claude Code Team
+
+**Date**: 2026-02-01
+**Evaluator**: Claude (Opus 4.5)
+**Status**: Integrated (4 sections in ultimate-guide.md)
+
+---
+
+## Resource Details
+
+**Source**: Blog post (thread synthesis)
+**URL**: https://paddo.dev/blog/claude-code-team-tips/
+**Title**: "10 Tips from Inside the Claude Code Team"
+**Author**: paddo.dev (synthesis of Boris Cherny thread)
+**Original thread**: x.com/bcherny/status/2017742741636321619
+**Date**: February 2026
+
+**Content type**: Practitioner tips from the Claude Code team at Anthropic (10 patterns)
+
+---
+
+## Summary
+
+Synthesis of 10 tips from the Claude Code team (Boris Cherny and colleagues at Anthropic). Covers parallelization, re-planning, self-improving rules, skills as institutional knowledge, bug-fixing workflows, prompting philosophy, terminal setup, subagent patterns, database skills, and learning workflows.
+
+---
+
+## Evaluation Score: 4/5
+
+**Rating**: High Value — 3 novel patterns + complements to existing sections
+
+### Justification
+
+**Strengths**:
+- Primary authoritative source (the actual Claude Code team at Anthropic)
+- 3 genuinely novel patterns not covered in guide:
+  1. **Prompting as Provocation** — challenge-based prompting philosophy with concrete patterns
+  2. **Model-as-Security-Gate** — using Opus as hook-based permission screener
+  3. **Shell aliases for worktrees** — practical navigation optimization
+- Enriches existing Boris Cherny case study with broader team context
+- Concrete, actionable examples (not abstract advice)
+
+**Weaknesses**:
+- Significant overlap with existing content (~50%):
+  - Parallelization via worktrees: already covered extensively
+  - CLAUDE.md as compounding memory: already documented in Boris case study
+  - Skills system: already documented (though team examples add value)
+  - Re-plan when stuck: Plan Mode already covered
+- Blog post is a synthesis, not primary source (original is a Twitter thread)
+- Some tips lack implementation detail (e.g., Opus security gate is conceptual)
+
+### Gap Analysis
+
+| Tip | Status in Guide | Action |
+|-----|----------------|--------|
+| 1. Parallelization (worktrees) | Already covered (section 10.3) | No action |
+| 2. Re-plan when stuck | Plan Mode covered (section 2.4) | Added to team patterns |
+| 3. Claude writes its own rules | CLAUDE.md covered (section 3.2) | Added to team patterns |
+| 4. Skills as institutional knowledge | Skills covered (section 5.3) | Added team examples |
+| 5. Claude fixes its own bugs | Debugging covered (section 9.1) | No action |
+| 6. Prompting as Provocation | **NEW** — not in guide | **Integrated** as section 2.6.1 |
+| 7. Terminal setup | Partially covered (Ghostty, statusline) | No action (marginal) |
+| 8. Subagents / Security gate | **NEW** — model-as-gate pattern | **Integrated** in hooks section |
+| 9. Claude replaces SQL | **NEW detail** — BigQuery skill example | Added to team patterns |
+| 10. Learning with Claude | Learning guide exists | No action |
+
+### Fact-Check
+
+- Boris Cherny is confirmed creator of Claude Code (verified in existing case study)
+- Thread is from verified @bcherny account
+- Patterns are consistent with Claude Code capabilities (hooks, skills, worktrees)
+- Opus-as-gate pattern is conceptual but technically feasible with current hook system
+- No invented metrics or unverifiable claims
+
+---
+
+## Integration Decision
+
+**Score**: 4/5 — Integrate within 1 week
+
+**Integrated as**:
+1. New section `### 2.6.1 Prompting as Provocation` (~30 lines) — after XML Prompting
+2. New section `### Advanced Pattern: Model-as-Security-Gate` (~25 lines) — after Testing Security Hooks
+3. Enriched Boris Cherny case study with "Team patterns" block (~18 lines)
+4. Shell aliases tip in worktrees section (~12 lines)
+
+**Not integrated** (already covered or marginal):
+- Parallelization tips (extensive existing coverage)
+- Terminal setup details (Ghostty already mentioned)
+- Bug-fixing workflow (debugging section sufficient)
+- Learning patterns (learning guide exists)