Backportcheck

backportcheck

A fix lands on the newest line, and then the harder question arrives: which of the older release branches still in the field need it too? Answering by gut feel either skips a branch that is quietly exposed or backports everything everywhere and burns the release team. backportcheck turns the decision into a fixed, auditable procedure: hand it the fix, and it hands back a plan.

First, the branches are filtered down to real candidates. A branch qualifies only when all three hold: it is still supported, its version is strictly older than the version the fix lands in, and — when you say which version introduced the bug — it is at or after that version, because a branch older than the bug cannot contain it. Versions are plain x.y.z numbers, compared numerically component by component, so 1.10.0 correctly sorts newer than 1.9.0.

Every branch that fails the filter is still reported, with exactly one reason, and the reasons are checked in a fixed order so the report never blames the wrong thing: an unsupported branch is unsupported even if it is also too new; next comes not older than fix version; last, predates bug introduction.

Each candidate then gets an action from the severity:

• critical — every candidate is backport. A critical fix goes everywhere it can.
• major — candidates on the same major line as the fix are backport; candidates on older major lines are consider.
• minor — candidates on the same major line are consider; candidates on older major lines are skip.

needs_backport is true exactly when at least one candidate's action is backport. The plan and the skipped list are each sorted by version descending, ties broken by branch name ascending, so the newest branches — usually the most urgent — come first. Malformed input is a validation error naming the offending path: a version that is not x.y.z, a severity outside its enum, a branch entry missing its name, version, or supported flag. The computation is pure and local: no network, no configuration, and no repository is read or touched — backportcheck only decides the plan.

CLI

npx @reneturcios/backportcheck check --input args.jsonnpx @reneturcios/backportcheck --version

args.json contains the full arguments object:

{  "fix_version": "3.2.0",  "severity": "major",  "introduced_in": "2.4.0",  "branches": [    { "name": "release-3.1", "version": "3.1.4", "supported": true },    { "name": "release-3.0", "version": "3.0.9", "supported": true },    { "name": "release-2.5", "version": "2.5.1", "supported": true },    { "name": "release-2.3", "version": "2.3.8", "supported": true },    { "name": "release-1.9", "version": "1.9.0", "supported": false }  ]}

The result is printed as JSON:

{  "needs_backport": true,  "fix_version": "3.2.0",  "severity": "major",  "plan": [    { "branch": "release-3.1", "version": "3.1.4", "action": "backport" },    { "branch": "release-3.0", "version": "3.0.9", "action": "backport" },    { "branch": "release-2.5", "version": "2.5.1", "action": "consider" }  ],  "skipped_branches": [    { "branch": "release-2.3", "version": "2.3.8", "reason": "predates bug introduction" },    { "branch": "release-1.9", "version": "1.9.0", "reason": "unsupported" }  ]}

Exit codes: 0 on success, 1 on a runtime error (including an unreadable or invalid input file, or invalid input), 2 on a usage error.

MCP server

npx -y @reneturcios/backportcheck mcp

MCP client config:

{  "mcpServers": {    "backportcheck": {      "command": "npx",      "args": ["-y", "@reneturcios/backportcheck", "mcp"]    }  }}

Tools

• check_backport — Decide whether a fix needs a backport, and to which release branches.

  • fix_version (string, required) — version the fix lands in, as x.y.z
  • severity (string, required) — one of critical, major, minor
  • branches (array, required, non-empty) — release branches, each {name, version, supported} with a non-empty string name, an x.y.z version, and a boolean supported
  • introduced_in (string, optional) — version that introduced the bug, as x.y.z

  Returns {needs_backport, fix_version, severity, plan, skipped_branches}.

Docker

docker run -i ghcr.io/cloudcorprecords/backportcheckdocker run --rm -v "$PWD:/w" ghcr.io/cloudcorprecords/backportcheck check --input /w/args.json

Development

npm installnpm run build   # tsc -> dist/npm test        # tsx --test test/*.test.ts (pure local, no network)npm run dev     # run the CLI from source

License

MIT — Copyright (c) 2026 Rene Turcios