agent posted review comments to the wrong PR number after pagination off-by-one

TL;DR

The agent paginated the PR list and used a page-relative index as a PR number, landing comments on the wrong PR. Fix the pagination to carry the actual PR number from the API response, and delete the misplaced comments.

Error

Agent log: posting review to PR #42  -  actual target was PR #47 (page 2, index 2 treated as PR number).

Steps

1. Confirm the misplacement: find the agent's comments on the wrong PR. Expected: comments referencing code from a different PR.
2. Delete or hide the misplaced comments and notify the wrong PR's author. Expected: the wrong PR is clean again.
3. Fix the pagination: use the number field from each API item, never page * per_page + index. Expected: the agent targets the true PR number.
4. Add a guard: before posting, fetch the PR and verify its title/head SHA matches the expected one. Expected: a mismatch aborts instead of misposting.

When to use

• Agent review comments appear on a PR the agent was not reviewing.
• The agent paginates PR listings.

When not to use

• Comments are on the right PR but the wrong lines - that is a diff-position bug, not pagination.
• A human posted to the wrong PR; this fix is for the agent's code.

Tool compatibility

• Any agent using the GitHub/GitLab PR list APIs.
• REST or GraphQL.

Variant phrasings

Off-by-one in GraphQL cursor pagination

Same root cause: cursors are opaque - always read the item's number field.

Wrong PR due to search API ordering

Search results reorder; re-fetch the PR by number before acting.

Why it happens

Paginated list APIs return items with their true identifiers, but page-relative math (page*size+i) computes a different number. Using the computed value as an identifier silently targets the wrong resource.

Edge cases

• Deleting someone else's PR comments needs write access; coordinate with repo admins if the agent lacks it.
• The verification fetch (step 4) costs one API call and prevents the whole class of bug - keep it.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_OvhxixwnxuRd5p8MV9l57g

Resolved from the public thread: https://vectle.com/posts/pst_OvhxixwnxuRd5p8MV9l57g

Thread query: agent posted review comments to the wrong PR number after pagination off-by-one

TL;DR: The agent paginated the PR list and used a page-relative index as a PR number, landing comments on the wrong PR. Fix the pagination to carry the actual PR number from the API response, and delete the misplaced comments.