---
phase: 10-proxy-pool
plan: 01
subsystem: crawler
tags: [proxy, round-robin, yaml-config, pydantic, playwright]

# Dependency graph
requires: []
provides:
  - ProxyPool class for multi-proxy management
  - ProxyEntry class for proxy state tracking
  - ProxyPoolConfig class for YAML configuration
  - Round-robin rotation strategy
  - Backward compatible env var loading
affects: [11-behavior-masking, 12-captcha-handling, zhihu-crawler]

# Tech tracking
tech-stack:
  added: []
  patterns:
    - Pydantic BaseModel for configuration
    - Lazy recovery check for cooldown
    - Round-robin with index pointer

key-files:
  created:
    - kb_workflow/crawler/proxy_pool.py
    - tests/test_crawler/test_proxy_pool.py
  modified: []

key-decisions:
  - "Use index pointer instead of itertools.cycle for better testability"
  - "Lazy cooldown check in get_next_proxy() instead of background timer"
  - "Fallback to first proxy when all unavailable"

patterns-established:
  - "Pattern: from_yaml() class method for file-based config loading"
  - "Pattern: from_env_fallback() for backward compatibility"

requirements-completed: [PROXY-01, PROXY-02]

# Metrics
duration: 3min
completed: "2026-03-18"
---

# Phase 10 Plan 01: Proxy Pool Core Summary

**Proxy pool infrastructure with YAML configuration, round-robin rotation, and backward compatible environment variable fallback**

## Performance

- **Duration:** 3 min
- **Started:** 2026-03-18T08:37:15Z
- **Completed:** 2026-03-18T08:40:28Z
- **Tasks:** 2
- **Files modified:** 2

## Accomplishments
- ProxyPool class manages multiple proxies with round-robin rotation
- ProxyEntry tracks proxy state including failures and availability
- YAML configuration loading from ~/.kb_proxies.yaml
- Backward compatible HTTPS_PROXY/HTTP_PROXY environment variable loading
- Lazy cooldown recovery check without background threads

## Task Commits

Each task was committed atomically:

1. **Task 0: 创建测试脚手架** - `bcf1a88` (test)
2. **Task 1: 实现 ProxyEntry + ProxyPool 核心类** - `c58a7d0` (feat)

_Note: TDD tasks have multiple commits (test → feat)_

## Files Created/Modified
- `kb_workflow/crawler/proxy_pool.py` - ProxyPool, ProxyEntry, ProxyPoolConfig classes
- `tests/test_crawler/test_proxy_pool.py` - 11 unit tests for proxy pool functionality

## Decisions Made
- Use index pointer (`_current_index`) for round-robin instead of `itertools.cycle` for better testability and predictable behavior
- Lazy cooldown check in `get_next_proxy()` instead of background timer to avoid threading complexity
- When all proxies are unavailable, fallback to first proxy instead of returning None

## Deviations from Plan

None - plan executed exactly as written.

## Issues Encountered
None - implementation followed RESEARCH.md pattern examples directly.

## User Setup Required

None - no external service configuration required.

## Next Phase Readiness
- Proxy pool core functionality complete
- Ready for Plan 02 (health check and failure recovery)
- Integration with ZhihuCrawler pending

---
*Phase: 10-proxy-pool*
*Completed: 2026-03-18*