JSON array three way merge

json-array-three-way-merge · version 1.0.0 · JSON & JSONL · free, no key needed

Merge base, left and right JSON arrays, returning deterministic output and explicit conflicting edit regions.

Use when you need to: merge three JSON arrays · three way JSON array merge · combine array edits from two branches.

Decide before calling

Read the versioned contract and the supported scope below. Reuse json-array-three-way-merge@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 json-array-three-way-merge@1.0.0 for merge three JSON arrays. 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

merge three JSON arrays
three way JSON array merge
combine array edits from two branches
detect JSON array merge conflicts
merge duplicate array values safely
reconcile ordered JSON lists

Not supported

merging JSON objects by key
reading JSON text or files

Behavior

Values are compared by RFC 8259 JSON structure with object member names sorted; array order and number spelling after parsing follow JavaScript JSON values.
Alignment uses longest common subsequence; on equal alternatives it advances the first input, a deterministic deletion-before-insertion tie rule. Duplicate values are identified by matched occurrence, never by value alone.
The implementation is synchronous, offline and deterministic and reports RFC 8259 + Myers 1986 and version 1.0.0.

Input

base (array of any JSON value, required): max items 128
left (array of any JSON value, required): max items 128
right (array of any JSON value, required): max items 128

Output

reference (constant "RFC 8259 + Myers 1986", required)
version (constant "1.0.0", required)
clean (boolean, required)
result (array of any JSON value, required): max items 256
conflicts (array of object, required): max items 256

Limits

max input bytes: 65536
max items: 128
max result items: 256
max iterations: 49152
max output bytes: 131072

Example

Request input:

{
  "base": [
    "a"
  ],
  "left": [
    "a",
    "b"
  ],
  "right": [
    "a"
  ]
}

Response:

{
  "result": {
    "reference": "RFC 8259 + Myers 1986",
    "version": "1.0.0",
    "clean": true,
    "result": [
      "a",
      "b"
    ],
    "conflicts": []
  }
}

How to call it

MCP

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

{
  "id": "json-array-three-way-merge",
  "version": "1.0.0",
  "input": {
    "base": [
      "a"
    ],
    "left": [
      "a",
      "b"
    ],
    "right": [
      "a"
    ]
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/json-array-three-way-merge/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"base":["a"],"left":["a","b"],"right":["a"]}'

The machine-readable contract is at /v1/tools/json-array-three-way-merge/versions/1.0.0.

CLI

node cli.mjs run json-array-three-way-merge 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

JSON keyed array merge: Three-way merge JSON arrays by a JSON Pointer key, returning edits, moves, inserts, deletes, and conflicts.
JSON array align: Align two JSON arrays with duplicate-safe occurrence pairs and deterministic LCS tie-breaking.
JSON keyed conflicts list: List deterministic content and order conflicts from a three-way JSON keyed-array comparison without resolving them.
JSON keyed resolution apply: Apply explicit choices to every keyed-array merge conflict and return the fully reconstructed JSON array.
JSON array merge verify: Verify a candidate JSON array against the deterministic three-way merge result and return an exact witness.
JSON array concat: Concatenate multiple JSON arrays of objects into one.