bridge: REQ-2026-04-16-mc-versioning — Gemini-approved fix for 26.x.x versioning

docs/code-bridge/requests/REQ-2026-04-16-mc-versioning.md

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+# REQ-2026-04-16-mc-versioning
+
+**From:** Chronicler #93  
+**Date:** 2026-04-16  
+**Priority:** HIGH — blocks all version detection in installer  
+**Status:** PENDING  
+**Consultation:** docs/consultations/gemini-modpack-installer-versioning-2026-04-16.md  
+
+---
+
+## Context
+
+Minecraft switched to calendar-based versioning in December 2025. Current version is `26.1.2`, not `1.21.4`. Our installer has hardcoded `1.21.1` as "latest" and the `javaVersionForMC()` function doesn't handle the new scheme. Gemini consulted, architecture locked.
+
+---
+
+## Changes Required
+
+### 1. Replace `javaVersionForMC()` in modpack-installer.js
+
+```javascript
+function javaVersionForMC(mcVersion) {
+  const major = parseInt(mcVersion.split('.')[0]);
+  
+  if (major >= 26) return 21; // New 2026+ calendar scheme
+  
+  if (major === 1) {
+    const minor = parseInt(mcVersion.split('.')[1]);
+    if (minor >= 21) return 21;
+    if (minor >= 17 && minor <= 20) return 17;
+    if (minor <= 16) return 8;
+  }
+  
+  return 21; // Frostwall fallback
+}
+```
+
+### 2. Replace hardcoded version lists with live DB-backed lookups
+
+Add a new DB table `mc_versions` to cache available versions:
+
+```sql
+CREATE TABLE mc_versions (
+  version VARCHAR(20) PRIMARY KEY,
+  java_version INT NOT NULL DEFAULT 21,
+  paper_supported BOOLEAN DEFAULT FALSE,
+  forge_supported BOOLEAN DEFAULT FALSE,
+  neoforge_supported BOOLEAN DEFAULT FALSE,
+  fabric_supported BOOLEAN DEFAULT FALSE,
+  updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
+);
+```
+
+Add a pg-boss cron job that runs at 3AM daily:
+- Hit Paper API for supported versions
+- Hit Modrinth `/tag/game_version` for all MC versions
+- Sort with `semver.rsort()` (add `semver` to package.json)
+- Upsert into `mc_versions` table
+
+Routes that currently show hardcoded version dropdowns should query this table instead.
+
+### 3. Update NextCloud mod stack lookup in modpackInstaller.js
+
+Replace direct path lookup with exact-then-fallback strategy:
+
+```javascript
+async function getNextCloudModStack(mcVersion) {
+  const exactPath = `standard-mods/${mcVersion}/`;
+  const baseRelease = mcVersion.split('.').slice(0, 2).join('.');
+  const fallbackPath = `standard-mods/${baseRelease}/`;
+
+  if (await webdav.exists(exactPath)) return exactPath;
+  if (await webdav.exists(fallbackPath)) return fallbackPath;
+  
+  throw new Error(`Mod stack missing for both ${exactPath} and ${fallbackPath}`);
+}
+```
+
+### 4. Update vanilla form version list
+
+Replace hardcoded MC version list in `_vanilla_form.ejs` with dynamic fetch from `mc_versions` table (Paper-supported versions only).
+
+### 5. Update modpack search version filter
+
+Replace hardcoded `1.21.1` option in `index.ejs` search filter with dynamic list from `mc_versions`.
+
+---
+
+## Notes
+
+- `standard-mods/1.21.1/` has been renamed to `standard-mods/26.1.2/` in NextCloud — the 5 mods are already there
+- NextCloud WebDAV correct path: `/remote.php/dav/files/mkrause612@gmail.com/`
+- Add `semver` to package.json
+
+---
+
+## Migration
+
+Migration 145: `mc_versions` table (see SQL above)
+
+## Deploy
+
+Standard pattern. Run migration 145 + npm install (semver) + restart.