Speed up schema diff reporting with bounded comparison

[inxilpro]

Summary

Replaces PHPUnit's full-document differ (which takes ~15 minutes on the Linear schema) with a bounded diff that walks both sides once, re-syncs over short runs of changes, and stops after a few hunks. This allows schema validation tests to complete in seconds rather than timing out.

Changes

• Added BoundedDiff support class (tests/Support/BoundedDiff.php): A line-by-line differ that:

  • Walks both documents once instead of weighing every line against every other
  • Re-syncs when lines match again (within a configurable window)
  • Stops after a configurable number of hunks
  • Truncates long runs of changes to avoid overwhelming output
  • Completes in milliseconds even on 40,000-line documents

• Added BoundedDiffTest (tests/Feature/BoundedDiffTest.php): Comprehensive test coverage including:

  • Matching documents
  • Single-line changes
  • Insertions that shift subsequent lines
  • Hunk limits
  • Documents that never re-sync
  • Performance validation (40,000 lines in <5 seconds)

• Updated SchemaFetcherTest to use BoundedDiff:

  • Compares schemas by hash first (fast path for no changes)
  • Only describes first few differences when schemas diverge
  • Replaces assertion with descriptive failure message

• Reduced CI timeout from 30 to 15 minutes: The bounded diff eliminates the need for extra time to render a 15-minute diff.

Implementation Details

The BoundedDiff algorithm:

1. Walks both sides in parallel, advancing when lines match
2. When lines diverge, searches forward up to window lines for a re-sync point (3+ matching lines)
3. Emits a hunk with context lines and truncated change bodies
4. Stops after max_hunks hunks or when no re-sync is found
5. Reports line numbers and counts to help locate changes in large documents

https://claude.ai/code/session_01XyfyD8QtJPci6seYNVdBXx