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test(demo): off-by-one in parseAddedLines, breaks 2 tests #1

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test(demo): off-by-one in parseAddedLines, breaks 2 tests #1

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2 changes: 1 addition & 1 deletion lib/publish.mjs
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,7 @@ export function parseAddedLines(patch) {
for (const row of patch.split('\n')) {
const hunk = row.match(/^@@ -\d+(?:,\d+)? \+(\d+)(?:,\d+)? @@/)
if (hunk) {
newLine = Number.parseInt(hunk[1], 10)
newLine = Number.parseInt(hunk[1], 10) + 1 // BUG: shifts every added line by one

@coderabbitai coderabbitai Bot Jul 8, 2026

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🎯 Functional Correctness | 🔴 Critical | ⚡ Quick win

The + 1 introduces an off-by-one error that breaks added-line numbering.

The hunk header's newStart (captured in hunk[1]) is already the correct RIGHT-side starting line number. Adding + 1 shifts every subsequent added line up by one. Tracing the test patch @@ -1,3 +1,4 @@:

  • With + 1: newLine starts at 2, context advances to 3, so +added-a→3, +added-b→4 → result {3,4} ≠ expected {2,3}.
  • Without + 1: newLine starts at 1, context advances to 2, so +added-a→2, +added-b→3 → result {2,3} ✓

This breaks the unit test in test/publish.test.mjs and causes partition() (line 62) to anchor inline comments to wrong lines, since lines.has(f.line) will mismatch findings against shifted line numbers.

🐛 Proposed fix: remove the off-by-one offset 
-      newLine = Number.parseInt(hunk[1], 10) + 1 // BUG: shifts every added line by one
+      newLine = Number.parseInt(hunk[1], 10)
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
newLine = Number.parseInt(hunk[1], 10) + 1 // BUG: shifts every added line by one
newLine = Number.parseInt(hunk[1], 10)
🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@lib/publish.mjs` at line 21, Remove the off-by-one offset in the hunk parsing
logic: `publish.mjs` currently initializes `newLine` from `hunk[1]` and then
adds 1, which shifts every added line number incorrectly. Update the line-number
tracking in the patch parsing flow so added lines use the hunk header’s
right-side start directly, and verify the downstream `partition()` mapping still
matches findings against `lines.has(f.line)` in `publish.test.mjs` expectations.

@DorianZheng DorianZheng Jul 8, 2026

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🛑 Off-by-one shifts every added line number
parseAddedLines(PATCH) returns {3,4} instead of {2,3}; ran node --test test/publish.test.mjs → 2/8 fail, causing inline comments to map to wrong lines or hit GitHub's 422 diff-line rejection.

Suggested change
newLine = Number.parseInt(hunk[1], 10) + 1 // BUG: shifts every added line by one
newLine = Number.parseInt(hunk[1], 10)

continue
}
if (row.startsWith('+++') || row.startsWith('---')) continue // defensive: file headers
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