- SQLite dedup race: add UNIQUE(collection_name, file_hash) and switch
save_document to a plain INSERT. add_document now catches the
IntegrityError from a concurrent add of the same content, cleans up its
managed files, and returns the winning doc_id — instead of two doc_ids
for one file (each having paid for its own LLM indexing).
- PDF image paths: store the absolute path to each extracted image
instead of a path relative to the indexing process's cwd. The
 references broke as soon as a query ran from a different
directory.
- LegacyCloudAPI: URL-encode doc_id / retrieval_id path segments (added
_enc()), matching CloudBackend. An id containing '/', '?', '#' or a
space previously hit the wrong endpoint or produced a malformed URL.
Adds regression tests: UNIQUE enforcement, the add-race resolving to the
winner, absolute image paths, and encoded legacy URLs.
Claude-Session: https://claude.ai/code/session_01Kx5DgKbhK1N8autqXH8SmS
