fix(notebook): handle plain-string outputs in _extract_output

[wallidsaydi-creator]

Summary

Converts the fix offered in #603 into a reviewable PR.

process_notebook corrupts cell outputs into one-character-per-line garbage whenever an output stores its text as a plain string rather than a list of strings — which the nbformat v4 schema explicitly allows for both stream.text and output.data["text/plain"] (the schema permits string | array of strings for multiline vs single-line storage).

A normal output like hello world currently renders as:

# Output:
#   h
#   e
#   l
#   l
#   o
#    
#   w
#   o
#   r
#   l
#   d

burning tokens and destroying readability for any notebook produced by a tool that serializes single-line outputs as strings (common in programmatic notebook generation and some exporter paths).

Root cause

_extract_output in src/gitingest/utils/notebook.py returned the raw value. The caller (_process_cell) then does raw_lines += _extract_output(output) — when the value is a str, list.__iadd__ iterates characters, and each character becomes its own # -prefixed line. cell["source"] in the same file already handles both forms correctly, so _extract_output was the only unguarded site.

Fix

Coerce the string form via splitlines() in both branches. This also restores correct rendering for multi-line string-form outputs, matching the list-form behavior line-for-line.

Verification

• Reproduced on stock main (4e259a0): string-form stream + execute_result outputs explode into per-character lines (regression test fails with the exact signature below).
• With the fix: both render as # hello world / # 42 on single lines; multi-line string form splits correctly.
• New regression test test_process_notebook_string_form_output in tests/test_notebook_utils.py — proven RED on stock (stash control) and GREEN with the patch.
• Full local suite: 152 passed (151 stock + this test). The only failures anywhere are 3 pre-existing network-dependent bitbucket cases in test_git_host_agnostic.py that fail identically on unpatched stock (verified via stash control).
• ruff check parity with stock (no new findings; the 2 CPY001 copyright notices are pre-existing on both trees).

Fixes #603

---

Context: I run FreshContext — a $5 pack that keeps AI coding agents off stale docs and deprecated patterns. Recently credited in llm-docs-builder v1.0.0 for a similar LLM-pipeline correctness fix, and have a merged fix in cloudflare-docs#32985.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-08-29T20:06:41.209850Z	aa2c3a4	PR opened

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review" or "@codex security review".

Codex reacts with 👀 while any review is running, comments if it has suggestions, and reacts with 👍 once all reviews finish with no findings.