feat(product): v1.5.2 hardening - compliance checklist, validation scripts, strict template enforcement

- Added CRITICAL COMPLIANCE CHECKLIST to implement.md with strict enforcement rules
- Added validation scripts: validate-prd.sh, validate-pdr.sh
- Restructured prd-template.md: Visual Summary = Section 1 (numbered), Document Info = Section 2
- Added compliance banners to section templates (overview.md, requirements.md)
- Added ASCII to Mermaid conversion instructions in implement.md
- Created TROUBLESHOOTING.md guide with common issues and fixes
- Updated README.md with validation scripts section
- Bumped extension version: 1.5.1 -> 1.5.2
- Bumped CLI version: 0.8.12+adlc9 -> 0.8.12+adlc10

Author: kanfil

extensions/product/CHANGELOG.md

@@ -2,6 +2,58 @@
 
 All notable changes to the Product extension will be documented in this file.
 
+## [1.5.2] - 2026-05-19
+
+### Added
+
+- **CRITICAL COMPLIANCE CHECKLIST**: Added strict compliance requirements to `commands/implement.md`
+  - MUST use templates (not generate from scratch)
+  - MUST use Mermaid diagrams (ASCII art prohibited in main content)
+  - MUST place Visual Summary as Section 1 (numbered)
+  - MUST validate output with validation scripts
+  
+- **Validation Scripts**: New bash scripts in `scripts/bash/`
+  - `validate-prd.sh`: Validates PRD compliance with v1.5.2 standards
+    - Checks Visual Summary is Section 1
+    - Detects ASCII diagrams in main content
+    - Validates Mermaid syntax
+    - Checks unfilled placeholders
+    - Verifies PDR traceability
+    - Supports `--strict` and `--warn` modes
+  - `validate-pdr.sh`: Validates PDR completeness
+    - Checks constitution is populated (not template)
+    - Validates required sections
+    - Reports inconsistency flags
+
+- **Template Compliance Banners**: Added to all section templates
+  - HTML comment banners at top of each template
+  - Reminds to use Mermaid (not ASCII)
+  - Notes section numbering in final PRD
+  - References validation script
+
+### Changed
+
+- **PRD Template Restructure** (`templates/prd-template.md`):
+  - Section 1: Visual Summary (now **numbered**)
+  - Section 2: Document Information (**new section**)
+  - Sections 3-13: Renumbered content sections
+  - Added compliance banner at top
+  - Added validation checklist at bottom
+  
+- **Hardened implement.md Command**:
+  - Added CRITICAL COMPLIANCE CHECKLIST at top
+  - Added STRICT ENFORCEMENT RULES section
+  - Enhanced template loading instructions (MUST read template first)
+  - Added ASCII to Mermaid conversion instructions
+  - Added validation step to section generation workflow
+
+### Fixed
+
+- **ASCII Diagram Detection**: Added explicit detection and conversion instructions
+  - ASCII diagrams only allowed in `<details>` blocks as fallbacks
+  - Main content MUST use Mermaid
+  - Added validation check for box-drawing characters
+
 ## [1.5.1] - 2026-05-19
 
 ### Fixed

extensions/product/README.md

@@ -128,6 +128,34 @@ Validate feature spec alignment with PRD (READ-ONLY).
 - Metric alignment
 - Traceability verification
 
+### Validation Scripts (v1.5.2+)
+
+Validate PRD/PDR compliance before or after generation:
+
+```bash
+# Validate PRD compliance (strict mode)
+.specify/extensions/product/scripts/bash/validate-prd.sh PRD.md --strict
+
+# Validate with warnings only
+.specify/extensions/product/scripts/bash/validate-prd.sh PRD.md --warn
+
+# Validate PDR completeness
+.specify/extensions/product/scripts/bash/validate-pdr.sh .specify/drafts/pdr.md
+```
+
+**Validation Checks:**
+
+- Visual Summary is Section 1 (numbered)
+- No ASCII diagrams in main content (Mermaid required)
+- All placeholders filled
+- PDR traceability for requirements
+- Constitution alignment (if claimed)
+
+**Exit Codes:**
+- `0`: All checks passed ✓
+- `1`: Errors found (strict mode)
+- `2`: Warnings only (warn mode)
+
 ## Workflow
 
 ### Greenfield Product
@@ -233,9 +261,30 @@ Located in `templates/sections/`:
 ## Templates
 
 - [pdr-template.md](./templates/pdr-template.md) - Product Decision Record format
-- [prd-template.md](./templates/prd-template.md) - Product Requirements Document format
+- [prd-template.md](./templates/prd-template.md) - Product Requirements Document format (v1.5.2: Visual Summary is Section 1)
 - `templates/sections/` - Individual section templates for DAG workflow
 
+### Template Compliance (v1.5.2+)
+
+All templates include compliance banners reminding you to:
+- ✓ Use Mermaid diagrams (NOT ASCII art)
+- ✓ Fill ALL [PLACEHOLDERS]
+- ✓ Trace content to PDRs
+- ✓ Validate with `./scripts/validate-prd.sh --strict`
+
+**Note:** v1.5.2 restructured `prd-template.md`:
+- Section 1: Visual Summary (numbered)
+- Section 2: Document Information
+- Sections 3-13: Content sections
+
+## Troubleshooting
+
+See [TROUBLESHOOTING.md](./TROUBLESHOOTING.md) for:
+- Common issues and fixes
+- ASCII to Mermaid conversion
+- Validation error resolution
+- Regeneration procedures
+
 ## Examples
 
 See [CNE Agent PRD example](../../CNE%20Agent%20(2).md) for a complete PRD example.