feat: add LaTeX/TikZ export for generated diagrams and plots

[YB0y]

Summary

• Adds TikZExporterAgent — a new VLM-powered agent that converts any generated image to compilable LaTeX source by reasoning about its visual structure
• Integrates export into the pipeline via --export-tikz (diagrams) and --export-pgfplots (plots); the .tex file is saved alongside the raster output in the same run directory
• Adds a standalone paperbanana tikz --input <image> subcommand for post-hoc conversion of any previously generated image
• Adds examples/tikz_export.py demonstrating all three usage patterns

Motivation

Academic venues (IEEE, ACL, NeurIPS camera-ready) require editable figure source files. Until now, the only output was raster images (PNG/JPEG/WebP), forcing researchers to manually redraw figures in TikZ after using PaperBanana for the conceptual work. This PR closes that gap without changing any existing behaviour — export is opt-in via flags.

Changes

Area	What changed
agents/tikz_exporter.py	New TikZExporterAgent extending BaseAgent; VLM call at temperature=0.2 with image + context; strips code fences; prepends metadata header
prompts/diagram/tikz_exporter.txt	Prompt instructing the VLM to produce a \begin{tikzpicture} snippet using only standard packages
prompts/plot/tikz_exporter.txt	Prompt for PGFPlots output with \begin{axis} structure
core/config.py	export_tikz: bool and export_pgfplots: bool settings; YAML key map entries
core/types.py	TIKZ_EXPORTER_START/END progress stages; tikz_path: Optional[str] on GenerationOutput
core/pipeline.py	Instantiates TikZExporterAgent; runs it after the final image is saved; writes .tex; populates result.tikz_path; budget/cost tracking included
cli.py	--export-tikz on generate; --export-pgfplots on plot; tikz_path printed in result output; new tikz subcommand
examples/tikz_export.py	Three documented patterns: generate+export, post-hoc export, plot+PGFPlots

Usage

# Generate + export TikZ in one shot
paperbanana generate \
  --input method.txt \
  --caption "Transformer encoder architecture" \
  --export-tikz
# → outputs/<run_id>/final_output.png
# → outputs/<run_id>/final_output.tex

# Convert an existing image post-hoc
paperbanana tikz \
  --input outputs/<run_id>/final_output.png \
  --source-context method.txt \
  --caption "Transformer encoder architecture"

# Statistical plot → PGFPlots
paperbanana plot \
  --data data.csv \
  --intent "Accuracy vs model size" \
  --export-pgfplots

Test plan

• paperbanana generate --input ... --caption ... --export-tikz produces a .tex file alongside the PNG with correct metadata header
• paperbanana tikz --input <existing_image> writes a .tex file to the same directory
• paperbanana plot --data ... --intent ... --export-pgfplots produces PGFPlots output
• --export-tikz absent → no .tex file written, result.tikz_path is None (no behaviour change)
• Emitted .tex compiles under pdflatex without errors on a sample diagram
• paperbanana tikz --help shows all flags correctly

Closes #174

[YB0y]

Hi @dippatel1994 I've opened PR for new feature. Could you please review this and share any feedback?

[dippatel1994]

Hey @YB0y, heads up that PR #145 by @itdeveloper1988 implements the same TikZ/LaTeX export feature for the same issue #137. PR #145 includes 19 tests while this one ships examples/tikz_export.py. Could you two coordinate on a single PR? Also lint is failing here - please run ruff check && ruff format and add tests for the agent and CLI paths.

[YB0y]

Hi @dippatel1994 Thank you for your feedback. I added test code and fixed lint error. Could you take another look at this?

[dippatel1994]

Tests added (14 functions covering extract_code, agent run, and CLI subcommand) and lint clean. Nice PGFPlots support and venue/header metadata. Thanks @YB0y!

[dippatel1994]

Hey @YB0y, CI is failing with SyntaxError: '(' was never closed and 4 lint errors. Looks like the merge with main introduced a syntax issue. Please check and fix locally - run python -c 'import paperbanana.cli' to find the unclosed paren, then ruff check to catch the rest.

[YB0y]

@dippatel1994 Thank you for taking the time to review my PR. I’ve resolved the conflicts and lint errors. Could you please take another look?

[dippatel1994]

Hey @YB0y, lint passes now but all 9 test jobs are still failing. Please check the test failures locally with pytest tests/ -v --tb=short and push a fix.

[dippatel1994]

Hey @YB0y, tests are still red. Two failures:

1. test_tikz_subcommand_help - assertion '--input' in output fails because Rich wraps the help text at narrow terminal widths in CI. Try setting terminal_width on the CliRunner or use --no-color / COLUMNS=200.
2. test_plot_accepts_export_pgfplots_flag - the --export-pgfplots flag is not rendered in plot help at all. Verify the flag is actually wired on the plot command.

[YB0y]

@dippatel1994 please review this.

[YB0y]

@dippatel1994 , I’d appreciate it if you could review this when you have time.