[Yipxiyi]

Summary

• validate repaired provider output inside the recursive safety fallback so incomplete or structurally invalid multi-row responses split into smaller requests
• treat persisted jobs without adaptive metadata as legacy custom jobs and preserve their manual concurrency, timeout, and retry settings
• preserve exact text-node whitespace when oversized leaf blocks are split and merged
• add missing v0.9.0 adaptive-processing notes and document these fixes under Unreleased
• add regression coverage for all three code paths

Root cause

The original adaptive reliability change validated provider rows only after returning from the recursive fallback, defaulted missing adaptive plan metadata to enabled, and normalized split output through element_text(). Those paths respectively bypassed splitting, overrode legacy settings, and collapsed significant whitespace.

Validation

• PYTHONPATH=src:tests python3 -m unittest discover -s tests -v — 84 passed
• python3 -m py_compile src/babel_epub/*.py
• npm test --prefix web — 8 passed
• npm run build --prefix web
• git diff --check

Follow-up to the unresolved review feedback on #3.