[Consolidation] Security track 9/9B/9C/10/11/12: remove 9B + 9C as standalone chapters (-1,050 lines) #1905

Problem

The security and governance track spans 1,669 lines across six chapters. The review shows that the same material is covered 3–5 times. Chapter 9B is 80% code bloat (Terraform module + stub Python). Chapter 9C is a stub (91 lines) that duplicates threat modelling.

Decisions required

Remove 9B as a standalone chapter

09b_security_patterns.md (647 lines) consists of:

• Lines 7–55: SOAR/AI-ML/observability — generic textbook prose → move to ch. 9 (10 lines)
• Lines 59–75: HashiCorp state protection — verbatim duplicate of 09:204–225 → DELETE
• Lines 77–282: Terraform "security foundation module" (200 lines) → move to an appendix
• Lines 286–310: Rego snippet with "omitted for brevity" → DELETE
• Lines 312–586: Python AdvancedThreatDetection with stub methods → DELETE (it is a façade)
• Lines 588–614: Future trends + recommendations + summary → replace with a 5-line summary
• Lines 616–647: Reference list identical to ch. 9 → DELETE

Merge 9C into ch. 9

09c_risk_and_threat_as_code.md (91 lines) duplicates threat modelling and risk topics. Retain the unique material (the risk-as-code YAML schema and chaos security, ~30 lines) as a new section in ch. 9.

Consolidate the rest

Specific cuts

• 12_compliance.md:67–252 — DELETE 175 lines of Python/YAML/Terraform under "Practical Examples" which are not compliance but infrastructure. Also contains autoscaling:* wildcard with a "least-privilege" comment (anti-pattern) and ECDSA P-384 labelled "Post-Quantum" (misleading).
• 12_compliance.md:57–65 — DELETE "Future-facing Considerations (Speculative)" — the author admits to the speculation.
• 11_governance_as_code.md:3–12 — DELETE Learning Objectives (inconsistent with the book's style).

Consequences and prerequisites

Must update:

• docs/book_index.json (remove 9B, 9C; add sections to 9)
• 33_references.md (references to 9B/9C)
• Tests in tests/test_completeness.py

Expected saving

~1,050 lines (63% of the track).

Source

Hard critical review of Parts C & D. See CUT_PROPOSAL.md.