abhigyanpatwari/GitNexus · error · InvalidBranchError

: branch name must not contain "@

Error message

${source}: branch name must not contain "@{".

What it means

validateBranchName rejects names containing '@{', which in git ref syntax is the reflog/revision prefix (e.g. '@{1}', 'branch@{yesterday}') and can never be part of a real branch name. Throwing here keeps reflog expressions out of a branch-name parameter, per git check-ref-format rules.

Solutions

  1. Pass a plain branch name; resolve the reflog/upstream expression first, e.g. `git rev-parse --abbrev-ref main@{u}`.
  2. Use the library's revision/commit options for '@{...}' expressions instead of the branch parameter.
  3. Strip or reject '@{' at your input boundary before invoking the API.

Example fix

// before
validateBranchName("main@{u}");
// after
const branch = execSync("git rev-parse --abbrev-ref main@{u}").toString().trim(); // e.g. "origin/main"
validateBranchName(branch);
Defensive patterns

Strategy: validation

Validate before calling

function hasReflogExpr(name) { return typeof name === "string" && name.includes("@{"); }
if (hasReflogExpr(branch)) throw new Error(`'${branch}' is a revision expression, not a branch`);

Type guard

function isPlainRef(v: unknown): v is string {
  return typeof v === "string" && !v.includes("@{");
}

Try / catch

try {
  validateBranchName(branch, "cli");
} catch (e) {
  if (e instanceof InvalidBranchError && e.message.includes('"@{"')) {
    console.error("Resolve @{...} expressions with git rev-parse first.");
    process.exitCode = 2;
  } else throw e;
}

Prevention

When it happens

Trigger: Calling validateBranchName with values like 'HEAD@{1}', 'main@{u}', or a revision expression pasted into the branch argument, e.g. `--branch main@{yesterday}`.

Common situations: Users copying reflog queries or upstream shorthand ('@{u}', '@{push}') into a branch field; scripts interpolating `git rev-parse` expressions; docs examples mixing revision syntax with branch parameters.

Understand the failure class

Background: "invalid id" errors: invalid identifier format — why libraries reject IDs before lookup, and how to fix them — this error's family across 37 libraries.

Related errors

AI-assisted analysis of abhigyanpatwari/GitNexus@ac9a4e9abd (2026-09-15). Data as JSON: /api/errors/73f7cb0e63881451. Report an issue: GitHub.

Appendix: source

Thrown at gitnexus/src/core/git-ref.ts:109

  // The remaining `git check-ref-format` rules. Without these the validator
  // accepted refs git itself refuses (`feature.lock`, `/feature`, `feature/`,
  // `feature//next`, `@`, `.hidden`), so the failure surfaced later from the
  // git subprocess instead of here. No real branch can violate them — git
  // could not have created one — so nothing that works today starts failing.
  if (trimmed.endsWith('.lock') || trimmed.split('/').some((part) => part.endsWith('.lock'))) {
    throw new InvalidBranchError(`${source}: branch name must not end with ".lock".`);
  }
  if (trimmed.startsWith('/') || trimmed.endsWith('/')) {
    throw new InvalidBranchError(`${source}: branch name must not start or end with "/".`);
  }
  if (trimmed.includes('//')) {
    throw new InvalidBranchError(`${source}: branch name must not contain consecutive slashes.`);
  }
  if (trimmed === '@') {
    throw new InvalidBranchError(`${source}: branch name must not be the single character "@".`);
  }
  if (trimmed.includes('@{')) {
    throw new InvalidBranchError(`${source}: branch name must not contain "@{".`);
  }
  if (trimmed.endsWith('.') || trimmed.split('/').some((part) => part.startsWith('.'))) {
    throw new InvalidBranchError(
      `${source}: branch name must not end with "." or have a path component starting with ".".`,
    );
  }
  // Git permits a backtick in a ref, but the branch is embedded inside a
  // Markdown inline-code span in the generated AGENTS.md/CLAUDE.md regression
  // example, where a backtick would close the span early and let the rest of
  // the template render as instruction text. Reject it at this single
  // chokepoint so all three tiers (CLI flag, .gitnexusrc, auto-detect via
  // sanitizeDetectedBranch) are covered (#1996 tri-review P1).
  if (trimmed.includes('`')) {
    throw new InvalidBranchError(
      `${source}: branch name must not contain a backtick (it would break the generated Markdown).`,
    );
  }
  return trimmed;

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