release: v3.28.1 - Visual Diagrams Series (40 Mermaid diagrams)

guide/diagrams/: new directory with 40 interactive Mermaid diagrams
- 10 thematic files: foundations, context/sessions, configuration,
  architecture, MCP ecosystem, dev workflows, multi-agent patterns,
  security/production, cost/optimization, adoption/learning
- Each diagram: Mermaid (GitHub-native) + ASCII fallback + source link
- Bold Guy palette (6-color system) consistent across all diagrams
- README with index, visual palette legend, navigation by use case

Also includes (backlog from v3.28.0→v3.28.1):
- guide/ultimate-guide.md: Managing Large MCP Server Sets, AI Code
  Disclosure Policy, claude-mem Gemini alternative, observability
- guide/workflows/plan-driven.md: Boris Tane custom markdown plans (+172L)
- guide/security-hardening.md: Part 4 PR security review workflow
- examples/agents/security-patcher.md: new security agent
- examples/hooks/bash/security-gate.sh: PreToolUse security hook
- guide/observability.md: activity monitoring, external tools, proxying
- docs/resource-evaluations/: 4 new evaluations (Boris Cherny, Moigneu,
  Boris Tane, Aristote AI instructions)
- README.md: Visual Diagrams section in "What Makes This Guide Unique"

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

machine-readable/reference.yaml

@@ -3,7 +3,7 @@
 # Source: guide/ultimate-guide.md
 # Purpose: Condensed index for LLMs to quickly answer user questions about Claude Code
 
-version: "3.28.0"
+version: "3.28.1"
 updated: "2026-02-17"
 
 # ════════════════════════════════════════════════════════════════
@@ -12,6 +12,12 @@ updated: "2026-02-17"
 # For architecture internals, see guide/architecture.md
 # ════════════════════════════════════════════════════════════════
 deep_dive:
+  # Visual Diagrams Series (40 Mermaid diagrams)
+  mermaid_diagrams:
+    path: "guide/diagrams/"
+    description: "40 interactive Mermaid diagrams: model selection, agent lifecycle, memory hierarchy, security threats, multi-agent patterns"
+    files: 10
+    total_diagrams: 40
   # AI-Assisted Development Workflows (from MetalBear/arXiv research)
   exploration_workflow: "guide/workflows/exploration-workflow.md"
   script_generation: "guide/workflows/iterative-refinement.md:192"
@@ -237,7 +243,7 @@ deep_dive:
   third_party_toad: "https://github.com/batrachianai/toad"
   third_party_conductor: "https://docs.conductor.build"
   # Configuration Management & Backup (Added 2026-02-02)
-  config_management_guide: "guide/ultimate-guide.md:4085"  # Section 3.28.0
+  config_management_guide: "guide/ultimate-guide.md:4085"  # Section 3.28.1
   config_hierarchy: "guide/ultimate-guide.md:4095"  # Global → Project → Local precedence
   config_git_strategy_project: "guide/ultimate-guide.md:4110"  # What to commit in .claude/
   config_git_strategy_global: "guide/ultimate-guide.md:4133"  # Version control ~/.claude/
@@ -1280,7 +1286,7 @@ ecosystem:
       - "Cross-links modified → Update all 4 repos"
     history:
       - date: "2026-01-20"
-        event: "Code Landing sync v3.28.0, 66 templates, cross-links"
+        event: "Code Landing sync v3.28.1, 66 templates, cross-links"
         commit: "5b5ce62"
       - date: "2026-01-20"
         event: "Cowork Landing fix (paths, README, UI badges)"
@@ -1292,7 +1298,7 @@ ecosystem:
 onboarding_matrix_meta:
   version: "2.0.0"
   last_updated: "2026-02-05"
-  aligned_with_guide: "3.28.0"
+  aligned_with_guide: "3.28.1"
   changelog:
     - version: "2.0.0"
       date: "2026-02-05"
@@ -1320,7 +1326,7 @@ onboarding_matrix:
       core: [rules, sandbox_native_guide, commands]
       time_budget: "5 min"
       topics_max: 3
-      note: "SECURITY FIRST - sandbox before commands (v3.28.0 critical fix)"
+      note: "SECURITY FIRST - sandbox before commands (v3.28.1 critical fix)"
 
     beginner_15min:
       core: [rules, sandbox_native_guide, workflow, essential_commands]
@@ -1405,7 +1411,7 @@ onboarding_matrix:
         - default: agent_validation_checklist
       time_budget: "60 min"
       topics_max: 6
-      note: "Dual-instance pattern for quality workflows (v3.28.0)"
+      note: "Dual-instance pattern for quality workflows (v3.28.1)"
 
   learn_security:
     intermediate_30min:
@@ -1416,7 +1422,7 @@ onboarding_matrix:
         - default: permission_modes
       time_budget: "30 min"
       topics_max: 4
-      note: "NEW goal (v3.28.0) - Security-focused learning path"
+      note: "NEW goal (v3.28.1) - Security-focused learning path"
 
     power_60min:
       core: [sandbox_native_guide, mcp_secrets_management, security_hardening]
@@ -1441,7 +1447,7 @@ onboarding_matrix:
       core: [rules, sandbox_native_guide, workflow, essential_commands, context_management, plan_mode]
       time_budget: "60 min"
       topics_max: 6
-      note: "Security foundation + core workflow (v3.28.0 sandbox added)"
+      note: "Security foundation + core workflow (v3.28.1 sandbox added)"
 
     intermediate_120min:
       core: [plan_mode, agents, skills, config_hierarchy, git_mcp_guide, hooks, mcp_servers]