Stable sort indices check

stable-sort-indices-check · version 1.0.0 · Numbers & math · free, no key needed

Check that claimed source indices are the exact ascending stable order for supplied integer keys.

Use when you need to: check stable sort indices · validate claimed sorting permutation · check argsort stability.

Decide before calling

Read the versioned contract and the supported scope below. Reuse stable-sort-indices-check@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 stable-sort-indices-check@1.0.0 for check stable sort indices. 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

• check stable sort indices
• validate claimed sorting permutation
• check argsort stability
• detect first index order discrepancy
• validate stable ordering certificate
• check sorted source positions

Not supported

• generate an argsort result
• accept partial or one based indices

Behavior

• Keys are canonical base-10 integer strings; negative zero is rejected, and null follows every integer.
• The expected permutation orders by key and then by ascending source index for ties, implementing ECMA-262 sort stability.
• Claimed indices are zero-based; the first mismatch is the lowest claim position and no replacement permutation is returned.
• Every verdict names ECMA-262-2026-draft-Array.prototype.sort.

Input

• source_keys (array of string or null, required): min items 1; max items 4096; each max length 40; each pattern ^(0|-?[1-9][0-9]*)$
• claimed_indices (array of integer, required): min items 1; max items 4096; each min 0; each max 4095

Output

• valid (boolean, required)
• reason (string, optional): min length 1; max length 80
• discrepancy (object, optional)
• reference_version (constant "ECMA-262-2026-draft-Array.prototype.sort", required)

Limits

• max items: 4096
• max key chars: 40

Example

Request input:

{
  "source_keys": [
    "2",
    "1",
    "1"
  ],
  "claimed_indices": [
    1,
    2,
    0
  ]
}

Response:

{
  "result": {
    "valid": true,
    "reference_version": "ECMA-262-2026-draft-Array.prototype.sort"
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "stable-sort-indices-check",
  "version": "1.0.0",
  "input": {
    "source_keys": [
      "2",
      "1",
      "1"
    ],
    "claimed_indices": [
      1,
      2,
      0
    ]
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/stable-sort-indices-check/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"source_keys":["2","1","1"],"claimed_indices":[1,2,0]}'

The machine-readable contract is at /v1/tools/stable-sort-indices-check/versions/1.0.0.

CLI

node cli.mjs run stable-sort-indices-check 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• Stable sort groups check: Check claimed equal-key groups for exact key order, membership, and stable source order.
• Stable sort result check: Check that a claimed record result is the exact ascending stable sort of the supplied source records.
• Permutation indices check: Check whether claimed indices are exactly one occurrence of every source index, reporting the first discrepancy.
• Precedence order check: Check whether a claimed node order is exactly a precedence-respecting linear extension of a caller-supplied DAG.
• Join inner result check: Check a claimed ordered inner join index result and report its first discrepancy.
• Join left result check: Check a claimed ordered left join index result and report its first discrepancy.