Fix: body-only updates incorrectly skipped in update_issue/update_pull_request handlers

[Copilot]

Campaign generator runs failed to update issues when only the body field was provided, logging "No update fields provided" and treating the operation as a no-op.

Root Cause

Body updates use internal fields (_rawBody, _operation) that are processed later by executeUpdate to handle append/prepend/replace operations. The validation logic in update_handler_factory.cjs filtered these out and incorrectly concluded no update was needed:

// Before: Skips when only internal fields present
const updateFields = Object.keys(updateData).filter(k => !k.startsWith("_"));
if (updateFields.length === 0) {
  return { success: true, skipped: true };
}

Changes

• update_handler_factory.cjs: Check for _rawBody existence before skipping validation
• update_handler_factory.test.cjs: Add test case for body-only updates

// After: Proceeds when _rawBody indicates pending body update
const updateFields = Object.keys(updateData).filter(k => !k.startsWith("_"));
const hasRawBody = updateData._rawBody !== undefined;

if (updateFields.length === 0 && !hasRawBody) {
  return { success: true, skipped: true };
}

Impact

Affects update_issue and update_pull_request handlers. The update_discussion handler is unaffected as it sets body directly without using the internal field pattern.

Original prompt

Investigate why campaign generator run skips update-issue:
No update fields provided for issue #11225 - treating as no-op (skipping update)
✓ Message 2 (update_issue) completed successfully
Run: https://github.com/githubnext/gh-aw/actions/runs/21239895948/job/61115627158

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