# Myers distance bounded

`myers-distance-bounded` · version 1.0.0 · Sequences & diffs · free, no key needed

Compute Myers insert/delete distance up to a caller cap, returning null predictably when the cap is exceeded.

**Use when you need to: compute bounded Myers distance · edit distance with a maximum cap · count insertions and deletions between sequences.**

## Decide before calling

Read the [versioned contract](/v1/tools/myers-distance-bounded/versions/1.0.0) and the supported scope below. Reuse `myers-distance-bounded@1.0.0` when your input, required output and limits match it. Choose another approach for an unsupported operation.

## Explain the choice

"I can use `myers-distance-bounded@1.0.0` for compute bounded Myers distance. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

## Supported

- compute bounded Myers distance
- edit distance with a maximum cap
- count insertions and deletions between sequences
- fail fast when diff distance is too high
- bounded shortest edit script length
- compare token arrays with Myers algorithm

## Not supported

- Levenshtein substitution distance
- producing edit operations (use myers-diff-bounded)

## Behavior

- Implements Myers 1986 shortest edit script with insertion and deletion cost one; substitution costs two.
- Search stops after max_distance; ties choose deletion before insertion and strings compare exactly by UTF-16 code units.

## Input

- `a` (array of string, required): max items 256; each max length 1024
- `b` (array of string, required): max items 256; each max length 1024
- `max_distance` (integer, required): min 0; max 512

## Output

- `reference` (constant "Myers 1986; RFC 3284 section 5", required)
- `version` (constant "1.0.0", required)
- `within_limit` (boolean, required)
- `distance` (integer or null, required): min 0; max 512

## Limits

- max input bytes: 131072
- max items: 256
- max item bytes: 1024
- max distance: 512
- max iterations: 263169
- max output items: 512

## Example

Request input:

```json
{
  "a": [
    "A",
    "B"
  ],
  "b": [
    "A",
    "C"
  ],
  "max_distance": 2
}
```

Response:

```json
{
  "result": {
    "reference": "Myers 1986; RFC 3284 section 5",
    "version": "1.0.0",
    "within_limit": true,
    "distance": 2
  }
}
```

## How to call it

### MCP

Connect `https://computefirst.net/mcp` ([setup](/docs#connect)), then call `execute` with:

```json
{
  "id": "myers-distance-bounded",
  "version": "1.0.0",
  "input": {
    "a": [
      "A",
      "B"
    ],
    "b": [
      "A",
      "C"
    ],
    "max_distance": 2
  }
}
```

### HTTP (no key)

```sh
curl -X POST https://computefirst.net/v1/tools/myers-distance-bounded/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"a":["A","B"],"b":["A","C"],"max_distance":2}'
```

The machine-readable contract is at [/v1/tools/myers-distance-bounded/versions/1.0.0](/v1/tools/myers-distance-bounded/versions/1.0.0).

### CLI

```sh
node cli.mjs run myers-distance-bounded 1.0.0 --input input.json --base-url https://computefirst.net
```

Get the client at [/clients/cli/](/clients/cli/).

## Related tools

- [Myers diff bounded](/tools/myers-diff-bounded): Produce a canonical Myers edit script within a caller distance cap, or a deterministic over-cap result.
- [Myers common subsequence](/tools/myers-common-subsequence): Return a canonical indexed LCS witness derived from bounded Myers search, or null when its cap is exceeded.
- [Sequence edit script](/tools/sequence-edit-script): Compute the Myers shortest edit script between two bounded sequences, with keep/delete/insert counts.
- [Sequence apply edit script](/tools/sequence-apply-edit-script): Apply a keep/delete/insert edit script to a bounded sequence with exact value matching and no fuzz.
- [Sequence key order check](/tools/sequence-key-order-check): Check an exact stable ordering claim for bounded records by a scalar key.
- [Sequence three way merge](/tools/sequence-three-way-merge): Three-way merge two sequence descendants against a shared base into clean or conflict regions.