{
  "slug": "jj-string-substr-allows-omitting-end-582453ef02c0",
  "title": "jj String.substr() allows omitting end",
  "tools": [
    "jj"
  ],
  "tags": [
    "agent"
  ],
  "introduced_at": "2026-04-02T05:17:00.000Z",
  "announced_at": "2026-04-02T05:17:00.000Z",
  "effective_at": null,
  "date_basis": "source-publication",
  "status": "unknown",
  "how": {
    "incantation": "When a jj template needs the substring from a start index through the string’s end, call `.substr(start)`; `end` is optional. [jj v0.40.0 release notes](https://github.com/jj-vcs/jj/releases/tag/v0.40.0)",
    "examples": [
      "<string>.substr(<start>)"
    ],
    "gotchas": [
      "Version: v0.40.0",
      "start (required): Zero-based start index, in UTF-8 bytes for String; negative values count from the end.",
      "end: Exclusive end index; negative values count from the end. Omit to return through the string’s end. No mutual-exclusion rule applies."
    ]
  },
  "why_it_matters": "Format a string template using a substring that extends to the string's end.",
  "sources": [
    "https://github.com/jj-vcs/jj/releases/tag/v0.40.0",
    "https://github.com/jj-vcs/jj/blob/main/docs/templates.md"
  ],
  "rank": 0.96014,
  "judge": {
    "publish": true,
    "judge_model": "codex-cli/gpt-6-luna+typesafe/jev-1.13.0",
    "prompt_version": "extract-v7+enrich-v2+judge-v2x3+jev-publish-v1"
  },
  "review_state": "approved",
  "provenance": {
    "run_id": "wave1b-tools-20261017",
    "verdict_id": "wave1b-tools-20261017:wave1b-tools-20261017-34044c1addbb4b79-1:gate",
    "evidence_hash": "44e36299f6c057798e890ce5ef92d45dcdc47f6447415ad1f831fe92f52e9efb"
  },
  "review": {
    "draft_hash": "2f5d9093e3327860da4cce60c302810bf9fa5a8bae9686f961115af8464a21e1",
    "reviewer": "publication-gate",
    "reviewed_at": "2026-10-07T00:00:00.000Z",
    "decision": "wave1b-tools-20261017:gate",
    "reason": "3 of 3 judge runs approved with p_yes >= 0.9 (mean 0.96 >= 0.9; 2 needed) and Jev gave 0.61 (>= 0.6 needed)."
  }
}