kb-skills/.planning/phases/13-llm/13-06-SUMMARY.md

phase, plan, subsystem, tags, requires, provides, affects, tech-stack, key-files, key-decisions, patterns-established, requirements-completed, duration, started, completed, tasks, files

phase	plan	subsystem	tags	requires	provides	affects	tech-stack	key-files	key-decisions	patterns-established	requirements-completed	duration	started	completed	tasks	files
13-llm	06	semantic-segmentation	strategy-pattern protocol unified-segmentation extensibility llm	phase provides 13-01 video-type-detection phase provides 13-02 semantic-boundary-detection phase provides 13-03 content-completeness-protection phase provides 13-04 title-generation phase provides 13-05 chinese-sentence-boundary	SegmentationStrategy Protocol interface for extensibility UnifiedSegmentationStrategy implementing unified approach (all video types) SemanticSegmentationEngine using strategy injection pattern Comprehensive test suite for strategy architecture	13-07-srt-processor-integration	added patterns strategy-pattern protocol-interface dependency-injection lazy-initialization	created modified kb_workflow/srt/semantic_engine.py (554 lines) tests/test_semantic_engine.py (992 lines)	Strategy Pattern with Protocol interface for extensibility (STRAT-01) Unified segmentation strategy for all video types (per user decision, STRAT-02) Strategy injection via constructor for easy testing and extension (STRAT-03)	Strategy Pattern: SegmentationStrategy Protocol defines interface Unified Strategy: Single strategy for all video types (Phase 13) Dependency Injection: SemanticSegmentationEngine accepts strategy via __init__ Lazy Initialization: AI client and fallback segmenter initialized on demand	STRAT-01 STRAT-02 STRAT-03	12min	2026-03-21T16:28:24Z	2026-03-21T16:40:15Z	1	2

Phase 13 Plan 06: Extensible Strategy Architecture Summary

Strategy Pattern with SegmentationStrategy Protocol interface and UnifiedSegmentationStrategy for all video types

Performance

• Duration: 12 min
• Started: 2026-03-21T16:28:24Z
• Completed: 2026-03-21T16:40:15Z
• Tasks: 1
• Files modified: 2

Accomplishments

• Implemented SegmentationStrategy Protocol interface defining the strategy contract
• Implemented UnifiedSegmentationStrategy with unified approach for all video types (per user decision)
• Refactored SemanticSegmentationEngine to use strategy injection pattern
• Added comprehensive test suite (10 tests) verifying strategy extensibility
• Preserved all existing functionality (video type detection, prompt building, fallback mechanism)

Task Commits

Each task was committed atomically:

1. Task 1: Implement extensible strategy architecture - 0d8ed1f (feat)

Plan metadata: (pending final commit)

Files Created/Modified

• kb_workflow/srt/semantic_engine.py - Added SegmentationStrategy Protocol, UnifiedSegmentationStrategy class, refactored SemanticSegmentationEngine to use strategy pattern (554 lines)
• tests/test_semantic_engine.py - Added TestStrategyPatternArchitecture (7 tests) and TestStrategyPatternIntegration (3 tests) for comprehensive strategy verification (992 lines)

Deviations from Plan

None - plan executed exactly as specified.

Implementation Details

SegmentationStrategy Protocol:

• Defines the segment() method signature for all strategies
• Uses Python's typing.Protocol for structural subtyping
• Enables runtime duck typing with compile-time type checking

UnifiedSegmentationStrategy:

• Implements unified approach for all video types (per user decision)
• Video type used only for prompt context, not for strategy selection
• Contains all LLM interaction logic moved from SemanticSegmentationEngine
• Preserves video type detection, prompt building, and fallback mechanisms

SemanticSegmentationEngine:

• Now uses strategy injection via constructor
• Defaults to UnifiedSegmentationStrategy when no strategy provided
• Delegates all segmentation logic to the strategy
• Simplified to a thin wrapper around the strategy

Test Coverage:

• TestStrategyPatternArchitecture (7 tests):
  • Protocol interface definition
  • UnifiedSegmentationStrategy implementation
  • SemanticSegmentationEngine uses strategy
  • Custom strategy injection
  • Unified strategy applies to all video types
  • Strategy switching doesn't affect functionality
  • Strategy extensibility for future types
• TestStrategyPatternIntegration (3 tests):
  • Preserves video type detection
  • Preserves prompt building
  • Preserves fallback mechanism

Decisions Made

Architecture Decision: Strategy Pattern with Protocol Interface

• Rationale: Enables future extension without modifying existing code (Open/Closed Principle)
• Protocol provides clear contract while allowing duck typing
• Easy to add new strategies (e.g., KnowledgeTypeStrategy, StoryTypeStrategy) in future

Design Decision: Unified Strategy for Phase 13

• Per user decision: No type-specific strategies in Phase 13
• Video type used only for prompt context, not strategy selection
• Architecture ready for type-specific strategies if needed later

Implementation Decision: Strategy Injection via Constructor

• Allows easy testing with mock strategies
• Supports runtime strategy switching if needed
• Follows dependency injection best practices

Requirements Completed

• STRAT-01: SegmentationStrategy Protocol interface defined ✅
• STRAT-02: UnifiedSegmentationStrategy implemented for all video types ✅
• STRAT-03: Strategy architecture supports extensibility (verified via custom strategy injection test) ✅

Next Phase Readiness

Ready for Phase 13 Plan 07 (SRTProcessor Integration):

• Strategy architecture complete and tested
• SemanticSegmentationEngine provides clean interface
• All existing functionality preserved
• No blockers or concerns

Architecture Benefits:

• Easy to add new strategies without modifying existing code
• Testable design with dependency injection
• Clear separation of concerns (engine vs strategy)
• Ready for future enhancements (type-specific strategies, advanced heuristics)

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Phase: 13-llm Plan: 06 Completed: 2026-03-21