[GGboya]

Fixes #626

bitstring 5.0.0 (released 2026-10-11) removed the old stream classes (BitStream / ConstBitStream). The dependency is declared as bitstring>=4.3.0 with no upper bound, so every fresh install now resolves to 5.x and crashes at import:

babeldoc/format/pdf/document_il/backend/pdf_creater.py", line 16, in <module>
    from bitstring import BitStream
ImportError: cannot import name 'BitStream' from 'bitstring'

Repo CI didn't catch this because it installs from uv.lock (still pinned to 4.x).

Fix

BitStream → BitArray in pdf_creater.py (17 references, single file):

• The file only uses the write-side .append() semantics — no pos / read / peek read-position API anywhere.
• In 4.x BitStream is a subclass of BitArray (MRO: BitStream → ConstBitStream → BitArray → Bits), so the swap is behavior-identical there.
• In 5.x BitArray is the mutable class, i.e. the forward-compatible spelling.

No version pin needed; compatible with both 4.x and 5.x.

Verification

Editable install of this branch, then the exact no-secret E2E from checks.yml:

babeldoc --openai --openai-api-key ci-dummy-key \
  --files examples/ci/test.pdf \
  --only-parse-generate-pdf --skip-scanned-detection

• bitstring 5.0.0: ✅ test.zh.dual.pdf / test.zh.mono.pdf generated
• bitstring 4.4.0: ✅ same
• ruff check on the changed file: clean

🤖 Generated with Claude Code

---

Summary by cubic

Fixes the import crash on fresh installs caused by bitstring 5.0.0 removing BitStream. The filed only uses .append() write semantics, and since 4.x BitStream is a subclass of BitArray, the swap is behavior-identical on both versions. CI didn't catch this because uv.lock still pins 4.x.

^{Written for commit 2dfae1c. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 1 file

_{View guided diff | Re-trigger cubic}