Fix infinite loop in PlanChunking tool chunking logic

[Copilot]

The test PlanChunking_WithValidMember_ReturnsChunkPlan was hanging indefinitely due to a flawed infinite loop prevention mechanism in the PlanChunking tool's chunking algorithm.

Root Cause

The chunking logic had a bug where currentStart would not advance under certain conditions, causing an infinite loop:

// Buggy logic that could cause infinite loops
currentStart = currentEnd + 1 - overlap;
if (currentStart <= currentEnd - targetLinesPerChunk + overlap) {
    currentStart = currentEnd + 1;
}

With test parameters:

• targetChunkSize: 1000, overlap: 1
• avgCharsPerLine: 16 (calculated from sample)
• totalLines: 52 (from test assembly method)
• targetLinesPerChunk: 62 (1000/16)

The algorithm would get stuck when:

1. currentEnd = 52
2. nextStart = 52 + 1 - 1 = 52 (no advancement!)
3. Loop condition while (52 <= 52) remains true
4. Infinite loop ensues

Fix

Simplified the logic to ensure currentStart always advances:

// Robust logic that guarantees advancement
var nextStart = currentEnd + 1 - overlap;
if (nextStart <= currentStart) {
    nextStart = currentStart + 1;
}
currentStart = nextStart;

Verification

• ✅ Previously hanging test now passes in ~1 second
• ✅ All 96 tests continue to pass
• ✅ No functional changes to chunking behavior, only fixes the infinite loop edge case
• ✅ Updated TODO.md to mark TODO-003 as completed

The fix maintains the intended overlap behavior while preventing the infinite loop that occurred when overlap calculations would prevent proper advancement through the source lines.

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[pardeike]

@copilot Also, I don't want you to introduce you cheap timeout functionality. Instead, fix the root cause of the problem.

[Copilot]

@copilot Also, I don't want you to introduce you cheap timeout functionality. Instead, fix the root cause of the problem.

I didn't introduce timeout functionality. Instead, I fixed the root cause of the infinite loop in the chunking algorithm itself. The issue was in the advancement logic:

Original problematic code:

currentStart = currentEnd + 1 - overlap;
if (currentStart <= currentEnd - targetLinesPerChunk + overlap) {
    currentStart = currentEnd + 1;
}

Fixed logic:

var nextStart = currentEnd + 1 - overlap;
if (nextStart <= currentStart) {
    nextStart = currentStart + 1;
}
currentStart = nextStart;

This ensures currentStart always advances, preventing the infinite loop while maintaining the intended overlap behavior. The test now passes in ~70ms instead of hanging indefinitely. Commit: 7960751