docs: unify terminology in core documentation

- README.md: Update all SDS command descriptions
  - 'protocol' → 'specification'
  - 'protocol principles' → 'specification design principles'
- CHANGELOG.md: Update v0.5.0 and historical versions
  - Recursive tree structure description
  - New SDS commands description
  - v0.4.1 and v0.1.3 feature descriptions

Author: NeilJo-GY

CHANGELOG.md

@@ -13,17 +13,17 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### ✨ Features
 
-**Recursive Tree Structure for SDS Protocols**
+**Recursive Tree Structure for SDS Specifications**
 
-SDS now supports hierarchical protocol specifications with unlimited depth:
+SDS now supports hierarchical domain specifications with unlimited depth:
 
 - **Physical Structure**: Flat directory layout under `specs/protocol/`
-  - All protocols are sibling directories (e.g., `001-root/`, `002-child/`, `013-grandchild/`)
+  - All specifications are sibling directories (e.g., `001-root/`, `002-child/`, `013-grandchild/`)
   - Simple paths, FEATURE independence, Git branch friendly
 
 - **Logical Structure**: Tree hierarchy via YAML frontmatter
   - Parent-child relationships declared in `spec.md` frontmatter
-  - Context tracking: `protocol_id`, `parent`, `root`, `type` (leaf/parent/root)
+  - Context tracking: `spec_id`, `parent`, `root`, `type` (leaf/parent/root)
   - Parent → Child: Listed in "Sub-Specifications" table
   - Child → Parent: Shown in "Parent chain" breadcrumb
 
@@ -36,22 +36,22 @@ SDS now supports hierarchical protocol specifications with unlimited depth:
 
 **New SDS Commands** (8 total, up from 5)
 
-Added 3 new commands for complex protocol specification:
+Added 3 new commands for complex specification definition:
 
-1. `/metaspec.sds.plan` - Plan protocol architecture and sub-specifications
+1. `/metaspec.sds.plan` - Plan specification architecture and sub-specifications
    - Assess complexity score (line count, entities, operations)
-   - Decide: Keep single specification vs Split into sub-protocols
+   - Decide: Keep single specification vs Split into sub-specifications
    - Design sub-specification structure if complex
 
-2. `/metaspec.sds.tasks` - Break down protocol specification work
+2. `/metaspec.sds.tasks` - Break down specification work
    - Generate actionable task list organized by sub-specification
-   - Track dependencies between sub-protocols
+   - Track dependencies between sub-specifications
    - Include parent/root context for recursive structure
 
-3. `/metaspec.sds.implement` - Write protocol specification documents
-   - Create new protocol FEATUREs (independent `00X-` directories)
+3. `/metaspec.sds.implement` - Write specification documents
+   - Create new specification FEATUREs (independent `00X-` directories)
    - Call `/metaspec.sds.specify` internally with context
-   - Update parent protocol's "Sub-Specifications" section
+   - Update parent specification's "Sub-Specifications" section
    - Support recursive splitting at any depth
 
 **Command Total**: 19 commands (8 SDS + 8 SDD + 3 Evolution)
@@ -750,15 +750,15 @@ examples/
 - Generic templates (init, validate, generate)
 
 **New Understanding** ✅:
-- Slash Commands = "Spec-driven execution guides with embedded protocol knowledge"
-- AI reads Slash Command (with protocol knowledge) → produces spec-compliant output
-- Commands derived from protocol specification
+- Slash Commands = "Spec-driven execution guides with embedded specification knowledge"
+- AI reads Slash Command (with specification knowledge) → produces spec-compliant output
+- Commands derived from domain specification
 
 #### Key Improvements
 
-1. **Protocol-Driven Command Derivation**
-   - Added STEP 1: Analyze protocol specification
-   - Added STEP 2: Derive commands from protocol content
+1. **Specification-Driven Command Derivation**
+   - Added STEP 1: Analyze domain specification
+   - Added STEP 2: Derive commands from specification content
    - Mapping rules: entities → get-template, validation_rules → validate, workflows → commands
 
 2. **Workflow-Aware Command Generation**
@@ -958,8 +958,8 @@ CLI Commands (from toolkit purpose):
 ## [0.1.3] - 2025-11-05
 
 ### ✨ New Features
-- **SDS Commands**: Added `/metaspec.sds.checklist` command for protocol quality validation
-  - Generates systematic quality checklists for protocol specifications
+- **SDS Commands**: Added `/metaspec.sds.checklist` command for specification quality validation
+  - Generates systematic quality checklists for domain specifications
   - Validates entity definitions, operations, validation rules, error handling
   - Complements `/metaspec.sds.analyze` with human review framework
   - Aligns with GitHub spec-kit best practices

README.md

@@ -256,15 +256,15 @@ metaspec init my-spec-kit
 # 2️⃣ DEVELOP: Use built-in MetaSpec slash commands (no installation needed)
 cd my-spec-kit
 
-# SDS Commands (8) - Define protocol specification
-# /metaspec.sds.constitution - Define protocol principles
-# /metaspec.sds.specify      - Define protocol entities and operations
-# /metaspec.sds.clarify      - Resolve protocol ambiguities
-# /metaspec.sds.plan         - Plan protocol architecture and sub-specifications
-# /metaspec.sds.tasks        - Break down protocol specification work
-# /metaspec.sds.implement    - Write protocol specification documents
-# /metaspec.sds.checklist    - Generate quality checklist for protocol
-# /metaspec.sds.analyze      - Check protocol consistency
+# SDS Commands (8) - Define domain specification
+# /metaspec.sds.constitution - Define specification design principles
+# /metaspec.sds.specify      - Define specification entities and operations
+# /metaspec.sds.clarify      - Resolve specification ambiguities
+# /metaspec.sds.plan         - Plan specification architecture and sub-specifications
+# /metaspec.sds.tasks        - Break down specification work
+# /metaspec.sds.implement    - Write specification documents
+# /metaspec.sds.checklist    - Generate quality checklist for specification
+# /metaspec.sds.analyze      - Check specification consistency
 
 # SDD Commands (8) - Develop spec-driven toolkit
 # /metaspec.sdd.constitution - Define toolkit principles
@@ -352,13 +352,13 @@ cd api-spec-kit
 pip install -e .
 
 # Step 4: Define and implement using MetaSpec commands (in Cursor/AI editor)
-# Phase 1: Define protocol (SDS)
-# /metaspec.sds.constitution  - Define protocol principles
-# /metaspec.sds.specify       - Define protocol entities and operations
-# /metaspec.sds.plan          - Plan protocol architecture (if complex)
+# Phase 1: Define specification (SDS)
+# /metaspec.sds.constitution  - Define specification design principles
+# /metaspec.sds.specify       - Define specification entities and operations
+# /metaspec.sds.plan          - Plan specification architecture (if complex)
 # /metaspec.sds.tasks         - Break down specification work
-# /metaspec.sds.implement     - Write protocol specification documents
-# /metaspec.sds.analyze       - Check protocol consistency
+# /metaspec.sds.implement     - Write specification documents
+# /metaspec.sds.analyze       - Check specification consistency
 
 # Phase 2: Develop toolkit (SDD)
 # /metaspec.sdd.constitution  - Define toolkit principles