Initial import from garrytan/gstack@026751e (main snapshot via local relay)

Source: https://github.com/garrytan/gstack/commit/026751e

scripts/resolvers/preamble/generate-upgrade-check.ts

@@ -0,0 +1,17 @@
+import type { TemplateContext } from '../types';
+
+export function generateUpgradeCheck(ctx: TemplateContext): string {
+  return `If \`PROACTIVE\` is \`"false"\`, do not auto-invoke or proactively suggest skills. If a skill seems useful, ask: "I think /skillname might help here — want me to run it?"
+
+If \`SKILL_PREFIX\` is \`"true"\`, suggest/invoke \`/gstack-*\` names. Disk paths stay \`${ctx.paths.skillRoot}/[skill-name]/SKILL.md\`.
+
+If output shows \`UPGRADE_AVAILABLE <old> <new>\`: read \`${ctx.paths.skillRoot}/gstack-upgrade/SKILL.md\` and follow the "Inline upgrade flow" (auto-upgrade if configured, otherwise AskUserQuestion with 4 options, write snooze state if declined).
+
+If output shows \`JUST_UPGRADED <from> <to>\`: print "Running gstack v{to} (just updated!)". If \`SPAWNED_SESSION\` is true, skip feature discovery.
+
+Feature discovery, max one prompt per session:
+- Missing \`${ctx.paths.skillRoot}/.feature-prompted-continuous-checkpoint\`: AskUserQuestion for Continuous checkpoint auto-commits. If accepted, run \`${ctx.paths.binDir}/gstack-config set checkpoint_mode continuous\`. Always touch marker.
+- Missing \`${ctx.paths.skillRoot}/.feature-prompted-model-overlay\`: inform "Model overlays are active. MODEL_OVERLAY shows the patch." Always touch marker.
+
+After upgrade prompts, continue workflow.`;
+}