fix(deep_research): join chapter body with real newline, not literal backslash-n

[Osamaali313]

Problem

report_read_chapter in functions/function_calling/deep_research.py joins the chapter body with the literal 2-character string "\n" (a backslash followed by n), not a newline:

# report_read_chapter, line 274
return "\\n".join(lines[start+1:end])

_read_report_lines builds lines with str.splitlines() (line 175), which strips the newlines, so the body must be re-joined with a real newline to reconstruct the text. Every sibling in this module does exactly that:

• _save_report → "\n".join(lines) (line 181)
• report_outline → "\n".join(outline) (line 298)
• report_read → returns read_text() (real newlines)

Only report_read_chapter uses "\\n". The result is that the tool returns the chapter with visible \n markers and no line breaks — one mangled line.

report_read_chapter is registered as an agent-callable tool (yaml_instance/deep_research_v1.yaml:347), so its return value is fed back to the model. Every time an agent reads a multi-line chapter back, it receives corrupted content — in the very deep-research workflow that assembles that report.

Reproduction

Reading a chapter whose body is two lines (Background line 1. / Background line 2.) via the real _read_report_lines + _find_chapter_range:

	join separator	real newlines	output
Before	"\\n" (backslash-n)	0	Background line 1.\nBackground line 2. (literal \n)
After	"\n" (newline)	1	proper two-line text

Fix

One character:

return "\n".join(lines[start+1:end])

No test suite covers deep_research.py today; the fix restores consistency with the three sibling functions in the same file.

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