Contingent later: tiny TEFAS cache backend if the device cannot reach TEFAS

[beagle1903]

Status

Contingent + later. Frozen spec: if device-TEFAS is impossible on the A23, a cache backend is a separate product decision. It is not a v1 task.

Do this only after (1) the browser-like TefasClient fails on the phone, and (2) we explicitly decide to add a server. Until then, isolate and swap the client only.

Why it exists as a tracked item

A cache would be more reliable than the phone hitting TEFAS (rate limits, Akamai). v1 chose no backend / no accounts to get a sideload APK first.

If we ever do it

• Same UI and FundRepository.
• Only TefasClient (or a new client behind it) changes.
• Still refresh followed funds, not the whole market on a timer.
• Failure still keeps last cache + follows.
• Multi-device sync is still out of v1 unless we reopen accounts (see accounts issue).

Explicitly not this

• HTML scraping of tefas.gov.tr
• Restoring BindHistory*
• Turning the app into a chat consultant or broker

Links

• Frozen spec §4 last paragraph + §14: https://github.com/beagle1903/fund-helper/blob/main/docs/superpowers/specs/2026-08-22-fund-helper-v1-design.md
• ADR 003 (local-only) and ADR 004 (device talks to TEFAS): https://github.com/beagle1903/fund-helper/blob/main/docs/decisions.md
• Architecture “Out of this map”: https://github.com/beagle1903/fund-helper/blob/main/docs/architecture.md
• Product durable facts: https://github.com/beagle1903/fund-helper/blob/main/docs/context.md

[beagle1903]

Issue board (opened 2026-08-31)

v1 remaining

• QA: Günlük on the A23 (empty, airplane HATA, Temizle) #26 QA: Günlük on the A23
• Contingent: swap TefasClient if TEFAS/Akamai blocks the phone #27 Contingent: swap TefasClient if TEFAS/Akamai blocks

After A23 / Play

• Play Store listing, privacy policy, and financial-features declaration #28 Play listing, privacy policy, financial-features
• Store/SPK-facing disclaimer (in-app sentence stays off) #29 Store/SPK-facing disclaimer
• Contingent later: tiny TEFAS cache backend if the device cannot reach TEFAS #30 Contingent: TEFAS cache backend

Out of v1 (tracked, not scheduled)

• Out of v1: BES / BEFAS as primary universe #31 BES / BEFAS
• Out of v1: charts, sparklines, and date-range history #32 Charts
• Out of v1: holdings, TL amounts, and cost basis #33 Holdings / cost basis
• Out of v1: accounts, login, and cloud sync #34 Accounts / login / sync
• Out of v1: iOS (and other non-Android clients) #35 iOS
• Out of v1: LLM / chat consultant #36 LLM / chat
• Out of v1: buy/sell recommendations (hard product rule) #37 Buy/sell recommendations

Milestones: https://github.com/beagle1903/fund-helper/milestones