# Sprint 11 Contract: MathJax Warning Mitigation

Status: Implemented
Last updated: 2026-05-11

## Objective

Add a conservative local cleanup pass for MathJax-invalid formulas:

1. Run the existing MathJax renderability check on normalized Markdown.
2. Build repair candidates only for expressions that failed MathJax validation.
3. Re-check each candidate with the same local checker.
4. Replace only candidates that pass.
5. Re-run final quality checks before writing Markdown, metadata JSON, and report Markdown.

The feature should reduce `MATH_RENDER_FAILED` warnings without hiding that a formula was changed.

## Current Precondition

- `pdf2md convert` writes normalized Markdown, metadata JSON, and `<stem>.report.md`.
- `pdf2md recheck` can rerun quality checks for an existing generated Markdown file without rerunning MinerU.
- Local MathJax checking is already optional and nonfatal.
- `outputs/MITC공부/MITC공부.md` currently has two MathJax render failures:
  - expression 8: `Double exponent: use braces to clarify`
  - expression 83: `Unknown environment 'a'`
- `samples/MITC공부.pdf` is the requested real local validation sample.

## Touched Surfaces

Allowed during implementation:

- `src/pdf2md/quality.py`
- `src/pdf2md/math_repair.py`
- `src/pdf2md/conversion.py`
- `src/pdf2md/ir.py`
- `tests/test_quality.py`
- `tests/test_math_repair.py`
- `tests/test_conversion.py`
- `tests/test_cli.py`
- `docs/Sprints/SPRINT11CONTRACT.md`
- `PLAN.md`
- `PROGRESS.md`

Not allowed:

- Remote OCR, remote LLMs, remote render APIs, or external document upload paths.
- Alternate PDF conversion engines.
- Switchable conversion-engine behavior.
- A full LaTeX parser or symbolic math rewrite engine.
- New CLI flags unless a later user request explicitly asks for them.
- Mandatory default tests that require real MinerU, GPU, Node.js, MathJax, network, Obsidian, or `samples/`.
- Committed files under `samples/`.
- Committed generated conversion outputs under `outputs/`.

## Product Behavior

Repair activation:

- Repair runs automatically when a local math checker is available and at least one math expression fails validation.
- If the checker is unavailable, behavior remains unchanged: conversion/recheck continues with an info-level unavailable-checker warning.
- The same repair path applies to fresh `convert` output and existing Markdown processed through `recheck`.

Initial deterministic repair rules:

- Repeated same-direction script repair:
  - Convert consecutive superscripts/subscripts such as `^ {i} ^ {t}` to `^ {i} {} ^ {t}`.
  - This resolves MathJax double-super/subscript syntax while preserving both script tokens.
- Truncated array environment repair:
  - Convert `\end{a}` to `\end{array}` only when the expression has unmatched `\begin{array}` / `\end{array}` counts.
  - This targets obvious extraction truncation, not arbitrary environment renaming.

Provenance:

- Applied repairs produce `MATH_RENDER_REPAIRED` info warnings.
- Successfully repaired expressions must not count as `math_render_error_count`.
- Unrepaired expressions keep the original `MATH_RENDER_FAILED` warning behavior.
- The report remains derived from metadata and local quality checks.

## Architecture Plan

### WP11.1: Failed Math Detail Capture

Actions:

- Add a project-owned result type that can include failed `MathExpression` records and checker messages.
- Preserve the current `check_math_renderability()` return behavior for existing callers.
- Keep expression extraction outside fenced code and inline code.

Expected output:

- Conversion can access failed expression spans without parsing warning message text.

### WP11.2: Repair Module

Actions:

- Add `src/pdf2md/math_repair.py`.
- Define repair result records.
- Generate candidates only for failed expressions.
- Revalidate candidates through the injected checker.
- Apply replacements from right to left so Markdown spans remain stable.

Expected output:

- Pure string-level repair behavior that is deterministic, local-only, and independently testable.

### WP11.3: Conversion And Recheck Integration

Actions:

- Route `convert` normalized Markdown through repair before final metadata/report construction.
- Route `recheck` Markdown through the same repair path before rewriting metadata/report.
- Re-run final quality checks after any repair.
- Preserve asset checking and strict-local behavior unchanged.

Expected output:

- Fresh conversions and rechecks both benefit from MathJax warning mitigation.

### WP11.4: Tests

Default tests:

- Repeated superscripts are repaired only when the original expression failed.
- `\end{a}` repairs to `\end{array}` only when array environments are unbalanced.
- A candidate that still fails is not written back.
- Passing expressions are not changed.
- Conversion writes repaired Markdown only after candidate revalidation.
- Recheck can repair an existing Markdown output and regenerate metadata/report.
- Existing unavailable-checker behavior remains nonfatal.

Optional local validation:

- Run `uv run pdf2md convert samples\MITC공부.pdf --out outputs\sprint11-MITC공부 --overwrite`.
- Confirm the generated report has `Math render error count: 0` for the requested sample, or record any remaining failures exactly.

## Acceptance Criteria

- Default fast tests pass without real MinerU, GPU, Node.js, MathJax, network, Obsidian, or `samples/`.
- `pdf2md convert` and `pdf2md recheck` share the same repair behavior.
- MathJax failed spans are repaired only after candidate revalidation succeeds.
- Successfully repaired formulas remain visible through `MATH_RENDER_REPAIRED` info warnings.
- Existing strict-local and MinerU-only constraints are unchanged.
- `samples/MITC공부.pdf` is validated locally as requested, with generated outputs kept ignored under `outputs/`.

## Hard Failure Criteria

- Repair changes a math span that did not fail initial MathJax validation.
- Repair drops an entire formula or removes meaningful LaTeX tokens solely to silence warnings.
- Repair claims success without re-running the local checker on the candidate.
- `convert` or `recheck` starts requiring MathJax when it was previously optional.
- Default tests require real MinerU, GPU, Node.js, MathJax, network, Obsidian, or `samples/`.
- `samples/` or generated `outputs/` files are committed.

## Verification Commands

```powershell
uv run pytest tests/test_quality.py tests/test_math_repair.py tests/test_conversion.py tests/test_cli.py tests/test_report.py
uv run pytest
uv run pdf2md convert samples\MITC공부.pdf --out outputs\sprint11-MITC공부 --overwrite
git diff --check
git status --short --untracked-files=all
```

## Handoff Requirements

After implementation:

- Update `PROGRESS.md` with files changed, commands run, test outcomes, sample validation outcome, known failures, and next action.
- Keep sample PDFs and generated outputs out of the commit.
- Commit the completed sprint if verification passes.

## Implementation Handoff

- Files changed: `src/pdf2md/quality.py`, `src/pdf2md/math_repair.py`, `src/pdf2md/conversion.py`, `src/pdf2md/ir.py`, tests, `ARCHITECTURE.md`, `docs/V1IMPLEMENTATIONPLAN.md`, `PLAN.md`, and `PROGRESS.md`.
- Default verification: `uv run pytest` passed 172 tests with 1 skipped.
- Targeted verification: `uv run pytest tests/test_quality.py tests/test_math_repair.py tests/test_conversion.py tests/test_cli.py tests/test_report.py` passed 56 tests.
- Requested sample verification: `uv run pdf2md convert samples\MITC공부.pdf --out outputs\sprint11-MITC공부 --overwrite` succeeded; final report shows `Math render error count: 0` and two `MATH_RENDER_REPAIRED` info warnings.
- Known failures: none.
- Residual risk: repair rules are deliberately narrow; future PDFs may expose MathJax failures that should remain warnings until a deterministic rule is added and tested.
- Next action: optional Obsidian visual review or additional sample validation.