fix(i18n): rescue unparseable translated MDX before attribute repair

[hxy91819]

Problem

Recent Translate Full runs kept failing at shard packaging even after the translation itself succeeded (e.g. run 33169524293: Docs MDX check passed (759 files) then mdx protected attribute repair failed). Root cause: the packaging-time repair chain parses every page with strict format: "mdx", while check-docs-mdx compiles pages by file extension (.md as plain Markdown). Translated pages with JSX-looking damage — fabricated <id> elements, stray closers, malformed attribute characters — therefore pass the workflow gate and only explode inside the repair chain, discarding otherwise complete (and expensive) translation shards.

Fix

Add a parser-guided syntax repair stage (.github/scripts/i18n/repair_mdx_syntax.mjs) that runs before the existing protected-attribute repair in package_artifact.py:

• Acceptance equals the downstream chain's own tolerant parser (parseMdx), and diagnosis reuses the same tolerant masking with an offset map (parseMdxForOffsets, now exported), so valid Markdown constructs — HTML comments, prose less-than — are never diagnosed or rewritten.
• Deterministic bounded loop (64 patches) keyed to the parser's own diagnostics: fabricated elements absent from the source are removed with prose kept (the diagnosed opener is located via a backward, comment/code-aware search — never the first same-name token); missing or stray closing tags are resynced; void elements are self-closed; unquoted attribute values are quoted (stopping before a /> delimiter); unterminated single-line comments are closed. Multi-line unterminated comments fail closed instead of guessing what stays hidden.
• Both repair writers now validate --locale as a single safe path segment before any write (the Python-side manifest validation previously ran only after Node had already written).
• Comment masking preserves UTF-16 code-unit length so astral characters cannot shift diagnostic offsets.
• Artifacts record mdx_syntax_repair_outcome; failed shards keep the existing empty-artifact contract for the weekly reconciliation. Docs updated in docs/.i18n/translation-workflow.md.

Testing

• 14-case parser-guided rescue matrix (fabricated/stray/void/attribute/comment/astral/mixed-prose scenarios) plus fail-closed cases, wiring test asserting syntax repair runs before protected-attribute repair, and locale-traversal rejection for both repair writers: python3 -m pytest .github/scripts/i18n/tests/test_i18n_scripts.py — 106 passed; 2 pre-existing failures unrelated to this change (test_translation_workflows_pin_latest_codex_and_tier_effort expects codex@0.146.0 while the workflow pins 0.146.1; a canary git-rebase test that also fails on pristine main in sandboxed environments), verified failing on unmodified HEAD.
• Structured review (autoreview, Codex gpt-5.6-terra xhigh): clean, no accepted/actionable findings after resolving review findings (locale traversal guard, flow-level fabricated element handling, adjacent stray-closer offsets, astral-safe masking, prose-aware diagnosis, />-aware value quoting).

[chatgpt-codex-connector]

You have reached your Codex usage limits for code reviews. You can see your limits in the Codex usage dashboard.