[markusbrand]

Summary

Fixes an issue where file and folder path segment sanitization rejected filenames containing the ASCII dollar sign ($) and Unicode currency or symbol characters (€, £, ¥, ©, ™, °, etc.) or Office temporary lockfiles (~$Document.docx).

When users uploaded or synced these files, the server returned 400 Bad Request: Unsafe path segment, causing persistent sync failures and warning states on desktop clients.

Changes

• Backend storage sanitization (backend/app/files/storage.py):
  • Updated _SAFE_SEGMENT_ASCII regex to include $.
  • Updated _is_safe_path_char to allow $ and Unicode category S (symbols, including currency Sc, math Sm, modifier Sk, and other symbols So).
• Tests (backend/tests/test_storage.py):
  • Added unit tests verifying resolve_user_path accepts $, €, £, ¥, ~$Doc.docx, ©, ™, and °.
• OpenSpec:
  • Scaffolded and validated fix-storage-symbol-path-sanitization change specification artifacts.

Verification

• Ran PYTHONPATH=backend .venv/bin/python -m pytest backend -q (110 passed).
• Ran full project QA suite ./scripts/run-qa.sh (all components passed: client-tauri, web, backend, docs).