[WIP] Fix failing GitHub Actions workflow for JavaScript

[Copilot]

Fix failing markdown_code_region_balancer tests

The markdown code region balancer is incorrectly treating consecutive, independent code blocks as nested fences, causing it to add extra backticks when none are needed.

Root Cause Analysis

• Analyze the algorithm's fence matching logic
• Identify why consecutive blocks are treated as nested
• Understand the "potential closers" logic

Fix Implementation

• Fix the algorithm to correctly distinguish between:
  • Truly nested fences (need escaping with extra backticks)
  • Consecutive independent blocks (should remain unchanged)
  • Code blocks with language-tagged examples inside (should remain unchanged)
• Ensure the fix handles all test cases

Solution Summary

Changed the escaping logic to:

1. Always use the last potential closer (farthest from opener)
2. Only escape (add extra backticks) if:
   • There are multiple bare fences at the same indentation
   • AND there are NO language-tagged fences in between
3. If language-tagged fences are present, treat bare fences as intentional documentation/examples, not errors

This distinguishes:

• Truly nested bare fences (e.g., AI errors): escape with extra backticks
• Documentation with code examples: don't escape (user knows what they're doing)
• Consecutive independent blocks: handled correctly

Testing & Validation

• Run markdown_code_region_balancer tests - ALL PASS (58 passed, 4 skipped)
• Run full test suite to ensure no regressions
• Run make agent-finish before committing

Original prompt

Fix the failing GitHub Actions workflow js
Analyze the workflow logs, identify the root cause of the failure, and implement a fix.
Job ID: 61070763482
Job URL: https://github.com/githubnext/gh-aw/actions/runs/21225360006/job/61070763482

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