Return every differing position between equal-width bit strings, preserving Hamming witnesses rather than just a count.

• Prepare the supplied left, right fields for this operation.
• Compare the complete example with the representation used by your own input before carrying the result into another step.

1. Enter left, right. Use the exact text syntax, units and index conventions explained below.
2. Run the tool. If input validation fails, correct the supplied fields before interpreting any result.
3. Read result.positions. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.

Require equal-length binary strings and collect each zero-based index where left and right differ.^[1]

• No alignment, insertion or deletion is attempted. Different input lengths are errors rather than compared with padding.
• Every bitstring is at most 128 characters and contains only literal zero and one.
• All declared input fields are required and unexpected top-level fields are rejected. Numbers must be finite; lists are limited to 128 entries and ordinary text fields to 8,192 UTF-16 code units, with tighter limits where stated.
• JSON text inputs must parse within bounded nesting and size limits. Numeric outputs outside the safe finite range are rejected; large exact integer results use decimal strings. Indexes and half-open spans are zero-based unless a rank is explicitly described as one-based.

Choose a packed-integer or textual-bit representation deliberately before combining operations. Preserve the documented index direction, width and exclusive boundaries; do not substitute a rank query for select.

• Bit String Next Set Position

  Find the first set bit at or after an explicit position; null preserves absence instead of inventing an index.

• Bit String Previous Set Position

  Find the last set bit strictly before an explicit position; null preserves absence instead of inventing an index.