Zen free tier incorrectly requires 'OpenCode 1.18.0 or newer' on Desktop v1.18.33 (API key auth) #52393

Description

Zen free-tier requests are rejected in OpenCode Desktop with OpenCode 1.18.0 or newer is required to use the free tier, even though the Desktop version (v1.18.33) is newer than 1.18.0. Affects all -free Zen models (e.g. muse-spark-1.3-contributor-free). Reported via Meta Muse Spark.

Plugins

No response

OpenCode version

Desktop v1.18.33 (no standalone CLI installed)

Steps to reproduce

1. Install / update to OpenCode Desktop v1.18.33 on Linux.
2. Authenticate Zen with an API key (not OAuth).
3. Select any free-tier Zen model (e.g. opencode/muse-spark-1.3-contributor-free or any -free model).
4. Send a message in Desktop chat.
5. Request is rejected with: OpenCode 1.18.0 or newer is required to use the free tier.

Expected: v1.18.33 satisfies >= 1.18.0, so free-tier requests should be accepted.

Suspected causes (to verify): Desktop may send a wrong/missing client version header on the Zen free-tier path (e.g. 1.18.33-desktop failing semver parsing, or header omitted on API-key auth), or the server-side gate compares versions as strings.

Note on possible duplicates: checked #49944 (1.18.30, no repro details) and #49918 (same error after update). This report adds Desktop v1.18.33 + API-key auth + Arch Linux repro, and the gate still fails on a version newer than both of those.

Screenshot and/or share link

Error text: OpenCode 1.18.0 or newer is required to use the free tier

Operating System

Arch Linux (Hyprland)

Terminal

Desktop app (not terminal); no local opencode CLI installed