Identical-content files at different workspace paths share one assets row
(assets.asset_id = blake3 content hash, PRIMARY KEY). The UPSERT
`ON CONFLICT(asset_id) DO UPDATE SET workspace_path = excluded` made
twin files overwrite each other's workspace_path on every ingest, so
`get_asset_by_workspace_path(path1)` returned the OTHER twin's row (or
None) — break idempotent unchanged-detection for both files.
Fix: switch try_skip_unchanged to document-centric lookup. `documents.
workspace_path` is already UNIQUE (V001) and `id_for_doc(path, ...)`
includes path, so each twin has its own stable document row. Compare
`doc.source_asset_id` with the new asset's checksum instead of going
through the assets table.
Dogfood (multi-root: kebab-docs + httpx + zod + lodash) showed 27 of
726 docs marked Updated on every idempotent re-ingest — all 27 are
twin-file victims (empty `__init__.py` ×3, AGENTS.md ↔ CLAUDE.md
same content, duplicate logo PDFs/JPGs).
After: re-ingest reports 0 new / 0 updated / 726 unchanged.
No schema migration needed.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
altair823
641b92af7d