Text unified diff

text-unified-diff · version 1.0.0 · Text · free, no key needed

Emit a one-file unified diff of two texts with comma counts and LF document breaks.

Use when you need to: text unified diff · emit unified diff · unified format text diff.

Supported

• text unified diff
• emit unified diff
• unified format text diff

Not supported

• preserve original CR/LF through unified text
• git diff --git headers
• index/binary markers
• multi-file patches
• binary patches
• fuzzy matching
• filesystem access

Behavior

• left and right are split with splitRecords; hunks use formatUnified with Myers SES and recordEqual.
• from_name and to_name default to a and b. Names must be non-empty, at most 1024 UTF-8 bytes, and must not contain NUL, CR, LF, or tab.
• context defaults to 3, may be 0, and is at most 16.
• The patch document always uses LF after every line, including headers and the final line.
• Hunk headers always include both counts with a comma, including count 1. Nonzero counts use 1-based starts; a zero count uses the GNU insertion index (0 at file start, otherwise the 1-based line before the empty range).
• Body prefixes are space (keep), minus (delete), and plus (insert). A following "\ No newline at end of file" line marks eol "".
• Identical texts yield unified "" and identical true, with no headers.
• Source CRLF is not encoded in the patch body; applying the emitted patch yields LF records except for the missing-final-newline marker.
• Unknown input fields are rejected.

Input

• left (string, required): max length 262144
• right (string, required): max length 262144
• from_name (string, optional): min length 1; max length 1024
• to_name (string, optional): min length 1; max length 1024
• context (integer, optional): min 0; max 16

Output

• unified (string, required): max length 1048576
• identical (boolean, required)

Limits

• max text bytes: 262144
• max line count: 4096
• max line bytes: 16384
• max path bytes: 1024
• max context: 16
• max hunks: 1024
• max output bytes: 1048576

Example

Request input:

{
  "left": "a\n",
  "right": "b\n"
}

Response:

{
  "result": {
    "unified": "--- a\n+++ b\n@@ -1,1 +1,1 @@\n-a\n+b\n",
    "identical": false
  }
}

How to call it

MCP

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

{
  "id": "text-unified-diff",
  "version": "1.0.0",
  "input": {
    "left": "a\n",
    "right": "b\n"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/text-unified-diff/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"left":"a\n","right":"b\n"}'

The machine-readable contract is at /v1/tools/text-unified-diff/versions/1.0.0.

CLI

node cli.mjs run text-unified-diff 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• Text apply unified patch: Apply a one-file unified patch to text at original line addresses with exact hunk matches.
• Text invert unified patch: Invert a one-file unified patch by swapping file names and delete/insert ops.
• Text parse unified patch: Parse a one-file unified patch into path names and 0-based hunks.
• Text conflict render: Render text and conflict parts as merge or diff3 conflict-marker text.
• Text diff stats: Summarize a line-record diff as keep, insert, delete, and hunk counts.
• Text line diff: Diff two texts as line records, preserving each line terminator.