feat(v2): V2 plugin API support

[kilng235]

Summary

V2 fork of opencode-visual-cache. Migrates src/index.tsx (~2238 → ~2220 lines) from the V1 plugin API to V2 Plugin.define({ id, setup }).

What's migrated

• Plugin entry: const tui: TuiPlugin = async (api) => … → export default Plugin.define({ id, setup(context) { … } }) from @opencode/plugin/tui
• Theme: V2 ResolvedTheme (no flat primary etc.) mapped to the 7-key palette the components expect (primary / text / textMuted / success / warning / error / border), desaturated through the existing Morandi ceiling
• KV: 30+ api.kv.get/set/ready → single context.storage.store("settings", { initial }) reactive pair; the .ready polling interval is gone
• Dialogs: all 9 <api.ui.DialogPrompt> / <api.ui.DialogSelect> JSX usages → imperative await context.ui.dialog.prompt / select. The chained dialog?.replace(...) + dialog?.clear() pattern collapses to plain awaits
• <api.ui.Prompt> override → prompt.footer.status slot (V2 doesn't let plugins replace the prompt input itself)
• Slots: api.slots.register({ slots: { sidebar_content } }) → context.ui.slot({ append: "sidebar.content", render })
• api.state.part(msgId) → iterate context.data.session.message.list(sid) and read msg.parts
• Commands: api.command.register() → context.keymap.layer(() => ({ commands: [{ slash, run }] }))
• api.state.session.{messages,get,cost} → context.data.session.message.list / get / cost
• api.lifecycle.onDispose(...) → return a single cleanup function from setup()
• api.route.current (used in 2 slash commands) → V2 commands receive sessionID directly in execute()

Behavior deltas

• OpenAI / non-OpenAI provider keys: V2 doesn't expose raw provider keys via api.state.provider. Non-OpenAI providers now require /cache-balance-key; OpenAI still works via the OAuth auth.json fallback.
• App.dataDir: doesn't exist on the V2 App interface. readOpenAIOAuthToken() derives paths from HOME / XDG_DATA_HOME / APPDATA directly.
• Provider pricing: V2 exposes models via context.client.model.list(); pricing is filled best-effort only when the list is synchronously resolvable, so the createEffect reactive graph doesn't block.
• Event subscriptions for token updates: V1 event.on("message.part.updated") has no exact equivalent; substituted with session.usage.updated + session.tool.success / session.tool.failed + session.idle.

Verification

• npm install ✅
• npm run build ✅ emits dist/tui.js (135 KB)
• npm run typecheck ✅
• npm run test:balance ✅
• src/server.ts deleted (V1 server stub no longer needed)

Compatibility

This is a V2-only fork. V1 OpenCode users should keep using the upstream opencode-visual-cache package. Installing @kilng235/opencode-visual-cache against V1 will not work.

If upstream accepts this back, a future change can add the dual-export pattern (per the V1→V2 migration guide) so a single package supports both.

[kilng235]

Closing — opened in wrong repo (targeted upstream instead of fork). Re-open manually at https://github.com/kilng235/opencode-visual-cache if you want to send upstream.