Layer 1: Insertion-time dedup in openrouter-extract-v2.py — skip if source_slug
already appears in claim content.
Layer 2: Insertion-time dedup in entity_batch.py — skip if PR number already
enriched this claim.
Layer 3: Post-rebase dedup in merge.py — scan rebased files for duplicate
evidence blocks (same source reference) and remove them before force-push.
Root cause: multiple enrichment branches modify the same claim at the same
insertion point. When rebased sequentially, evidence blocks are duplicated.
(Leo: PRs #1751, #1752)
lib/dedup.py: standalone module — parses evidence headers, deduplicates by
source key, preserves trailing content (Relevant Notes, Topics sections).
9 tests covering all patterns including the real PR #1751 duplication case.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
