{
  "slug": "wrangler-previews-block-accepts-placement-configuration-c556450408ca",
  "title": "wrangler previews block accepts placement configuration",
  "tools": [
    "wrangler"
  ],
  "tags": [
    "agent"
  ],
  "introduced_at": "2026-09-16T20:30:32.000Z",
  "announced_at": "2026-09-16T20:30:32.000Z",
  "effective_at": null,
  "date_basis": "source-publication",
  "status": "unknown",
  "how": {
    "incantation": "When a Worker needs a Preview placement different from production, set `placement` inside the Wrangler `previews` block; this overrides top-level placement for Previews.",
    "examples": [
      "{\"placement\":{\"region\":\"<provider>:<region>\"},\"previews\":{\"placement\":{\"mode\":\"smart\"}}}"
    ],
    "gotchas": [
      "Version: 4.133.0",
      "previews.placement: Preview placement configuration; overrides top-level placement for Previews.",
      "placement.mode: Set to `\"smart\"` for automatic placement near back-end services.",
      "placement.region: Cloud region in `{provider}:{region}` format, such as `aws:us-east-1`.",
      "placement.host: Hostname and port for a single-homed layer 4 service.",
      "placement.hostname: Hostname for a single-homed layer 7 service.",
      "placement choice: `mode`, `region`, `host`, and `hostname` are mutually exclusive placement options.",
      "Prerequisite: Use a Wrangler configuration file. Deployable Workers require `name`, `main`, and `compatibility_date` (with `main` optional for assets-only Workers)."
    ]
  },
  "why_it_matters": "Configure a Worker’s Preview placement independently from its production placement.",
  "sources": [
    "https://github.com/cloudflare/workers-sdk/releases/tag/wrangler%404.133.0",
    "https://developers.cloudflare.com/workers/previews/configuration/",
    "https://developers.cloudflare.com/workers/configuration/placement/",
    "https://developers.cloudflare.com/workers/wrangler/configuration/"
  ],
  "rank": 0.92023,
  "judge": {
    "publish": true,
    "judge_model": "codex-cli/gpt-6-luna+typesafe/jev-1.13.0",
    "prompt_version": "extract-v7+enrich-v1+judge-v2x3+jev-publish-v1"
  },
  "review_state": "approved",
  "provenance": {
    "run_id": "regrade-20261008",
    "verdict_id": "regrade-20261008:by-tool-wrangler-20261002--item-326a3b24305624cb87f6b91b:gate",
    "evidence_hash": "3602a30ddf6066bf5e1197864c9ba9d42b171c0e9afcda3bd7698833b5967b7c"
  },
  "review": {
    "draft_hash": "3615877b334065ab296e86246be6d1f04592023cf6712f0928249579fadc5897",
    "reviewer": "publication-gate",
    "reviewed_at": "2026-10-07T00:00:00.000Z",
    "decision": "regrade-20261008:gate",
    "reason": "3 of 3 judge runs approved with p_yes >= 0.9 (mean 0.92 >= 0.9; 2 needed) and Jev gave 0.73 (>= 0.6 needed)."
  }
}