---
phase: 04-analysis-orchestration
plan: 02
subsystem: pipeline-architecture
tags: [processor, download, metadata, content, tdd, pydantic]

requires:
  - phase: 01-foundation
    provides: WorkflowStateManager, StepInput/StepOutput schemas
  - phase: 02-platform-skills
    provides: BilibiliAdapter, ZhihuAdapter
  - phase: 04-analysis-orchestration
    plan: 04-01
    provides: BaseProcessor, ParseProcessor
provides:
  - DownloadProcessor for unified metadata and content downloading
  - DownloadInput/DownloadOutput schemas for download step
affects: [04-03, 04-04, 04-05]

tech-stack:
  added: []
  patterns:
    - "TDD workflow: RED (failing tests) -> GREEN (implementation) -> commit"
    - "PlatformAdapter integration for multi-platform support"
    - "Content type discrimination (video vs article)"

key-files:
  created:
    - kb_pipeline/processors/download.py
    - tests/test_processors/test_download.py
  modified:
    - kb_pipeline/schemas.py
    - kb_pipeline/processors/__init__.py

key-decisions:
  - "Video content skipped in download step (handled by ASR in Phase 3)"
  - "Text content (article, answer, zhuanlan) downloaded and saved as Markdown"
  - "Metadata and content files follow naming convention: {platform}_{id}_{suffix}"
  - "State recording on success/failure with summary info"

patterns-established:
  - "DownloadProcessor uses PlatformAdapter for platform-specific operations"
  - "Idempotency: skip step if already completed in workflow state"

requirements-completed: [MNT-01]

duration: 7min
completed: 2026-03-13
---

# Phase 04 Plan 02: DownloadProcessor Summary

**Unified DownloadProcessor for metadata extraction and content downloading across Bilibili and Zhihu platforms**

## Performance

- **Duration:** 7 min
- **Started:** 2026-03-13T15:17:17Z
- **Completed:** 2026-03-13T15:24:11Z
- **Tasks:** 3
- **Files modified:** 4

## Accomplishments
- DownloadInput/DownloadOutput schemas with proper validation
- DownloadProcessor correctly fetching metadata from Bilibili and Zhihu adapters
- Content downloading for text-based content (article, answer, zhuanlan)
- Video content marked for ASR processing (not downloaded in this step)
- State recording on success/failure
- Module export from kb_pipeline.processors

## Task Commits

Each task was committed atomically:

1. **Task 1: Define Download Schemas** - `9d5c3ff`/`1e01236` (test/feat)
2. **Task 2: Create DownloadProcessor with metadata fetching** - `567bd32`/`fc6fba7` (test/feat)
3. **Task 3: Add content downloading and __init__.py export** - `ec268f7` (feat)

**Plan metadata:** pending (docs: complete plan)

_Note: TDD tasks may have multiple commits (test -> feat -> refactor)_

## Files Created/Modified
- `kb_pipeline/processors/download.py` - DownloadProcessor implementation with metadata and content handling
- `kb_pipeline/processors/__init__.py` - Added DownloadProcessor to exports
- `kb_pipeline/schemas.py` - Added DownloadInput and DownloadOutput schemas
- `tests/test_processors/test_download.py` - Comprehensive tests (17 test cases)

## Decisions Made
- Video content is not downloaded (handled by ASR in Phase 3)
- Text content is downloaded and saved as Markdown with YAML frontmatter
- File naming follows pattern: `{platform}_{content_id}_{suffix}`
- State recording uses summary format: `title={title}, type={content_type}`

## Deviations from Plan

None - plan executed exactly as written.

## Issues Encountered
- Test mock path needed adjustment: mock `kb_pipeline.processors.base.get_settings` because BaseProcessor.__init__ calls get_settings()
- Zhihu adapter mock needed AsyncMock for fetch_content method

## User Setup Required

None - no external service configuration required.

## Next Phase Readiness
- DownloadProcessor provides metadata and content for downstream analysis
- Video content flow: DownloadProcessor (metadata) -> ASRProcessor (transcription)
- Article content flow: DownloadProcessor (metadata + content) -> AnalysisProcessor

---
*Phase: 04-analysis-orchestration*
*Completed: 2026-03-13*

## Self-Check: PASSED

All files verified:
- kb_pipeline/processors/download.py
- kb_pipeline/processors/__init__.py
- kb_pipeline/schemas.py
- tests/test_processors/test_download.py

All commits verified:
- 9d5c3ff: test(04-02): add failing tests for DownloadInput/DownloadOutput schemas
- 1e01236: feat(04-02): add DownloadInput and DownloadOutput schemas
- 567bd32: test(04-02): add failing tests for DownloadProcessor metadata fetching
- fc6fba7: feat(04-02): implement DownloadProcessor with metadata fetching
- ec268f7: feat(04-02): add content downloading and module export for DownloadProcessor