feat(channels): migrate doubao/douyin to thick fetch() with bounded retry

[1012839419a-alt]

Summary

doubao_research and douyin_detail declared capabilities (default_rate, auth_kind) but never overrode fetch(), so run_channel treated them as unmigrated: no runner protocol, and CDP race failures ("CDP connection is not open", "Inspected target navigated or closed", "cloneNode") had no retry semantics — the outer worker had to brute-force retry, and a captcha wall was the only classified error.

Changes

• doubao_research_channel: classify transient CDP races as ConnectionError (retryable in error_taxonomy) alongside the existing captcha_challenge classification; add fetch() override with exponential-backoff bounded retry (max_retries default 3, retry_base_delay default 2s). Captcha is NEVER auto-retried — the pipeline's captcha branch (PR fix(control): close the captcha governance loop #65) pauses the source for a human.
• douyin_detail_channel: same transient classification on open/eval failures + same fetch() retry loop; permanent failures fail immediately.
• collect() stays the single source of truth in both; ctx.http is not threaded through (subprocess transport, same trade-off as opencli_channel.fetch()).

Test Plan

• doubao: 19 tests (7 new) — retry-then-success, give-up after max_retries, captcha/permanent never retried, metadata passthrough, CDP transient classification
• douyin: 6 tests (3 new) — same retry semantics
• channel contract + runner suites: green (38 passed total)

Note: kept independent of PR #65 (captcha governance) so each merges separately; uses inline captcha_challenge marker instead of is_captcha() for that reason.

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📥 Commits

Reviewing files that changed from the base of the PR and between 94ab53d and a440d81.

📒 Files selected for processing (4)

• backend/channels/doubao_research_channel.py
• backend/channels/douyin_detail_channel.py
• tests/unit/channels/test_doubao_research_channel.py
• tests/unit/channels/test_douyin_detail_channel.py

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[repowise-bot]

⚠️ Health of changed files: 8.5 → 8.4 (-0.1)
_{🚨 Change risk: high, riskier than 73% of this repo's commits.}

📋 At a glance
3 files changed health · 3 hotspots touched · 4 new findings introduced.

Files & modules (2)

• backend (2 files)
  • backend/channels/douyin_detail_channel.py
  • backend/channels/doubao_research_channel.py
• tests (2 files)
  • .../channels/test_douyin_detail_channel.py
  • .../channels/test_doubao_research_channel.py

✅ Health gate: passed

🔎 More signals (2)

🗺️ Change map

flowchart LR
  subgraph PR ["Changed in this PR (2 with dependents)"]
    f_backend_channels_doubao_research_channel_py["backend/channels/doubao_research_channel.py 🔥"]:::changed
    f_backend_channels_douyin_detail_channel_py["backend/channels/douyin_detail_channel.py 🔥"]:::changed
  end
  f_backend_channels_registry_py["backend/channels/registry.py"]
  f_backend_channels_doubao_research_channel_py --> f_backend_channels_registry_py
  f_backend_channels_douyin_detail_channel_py --> f_backend_channels_registry_py
  classDef changed fill:#dbeafe,stroke:#1d4ed8,color:#1e3a5f
  classDef warn fill:#fef3c7,stroke:#b45309,color:#78350f
  classDef guard fill:#dcfce7,stroke:#15803d,color:#14532d

Loading

_{Solid arrows: code that imports the changed files (1 direct dependent, from the last indexed snapshot). Dashed: history/tests.}

🔥 Hotspots touched (3)

• backend/channels/doubao_research_channel.py: 2 commits/90d, 2 dependents · primary owner: 2233admin (70%)
• .../channels/test_doubao_research_channel.py: 2 commits/90d, 0 dependents
• backend/channels/douyin_detail_channel.py: 1 commits/90d, 2 dependents · primary owner: 2233admin (100%)

👀 Suggested reviewers @2233admin

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