remove completed todo

TODO.md

@@ -33,28 +33,6 @@ opts ESPP/HSA accounts into cash-based attribution.
 Related: ESPP-style accrual blind spot in the "Audit: manual-check
 accounts mechanism" section above.
 
-## On-demand server-side fetch for new symbols
-
-Currently the server's SRF endpoints (`/candles`, `/dividends`, etc.) are pure
-cache reads - they 404 if the data isn't already on disk. New symbols only get
-populated when added to the portfolio and picked up by the next cron refresh.
-
-Consider: on a cache miss, instead of blocking the HTTP response with a
-multi-second provider fetch, kick off an async background fetch (or just
-auto-add the symbol to the portfolio) and return 404 as usual. The next
-request - or the next cron run - would then have the data. This gives
-"instant-ish gratification" for new symbols without the downsides of
-synchronous fetch-on-miss (latency, rate limit contention, unbounded cache
-growth from arbitrary tickers).
-
-Note that this process doesn't do anything to eliminate all the API keys
-that are necessary for a fully functioning system. A more aggressive view
-would be to treat ZFIN_SERVER as a 100% source of record, but that would
-introduce some opacity to the process as we wait for candles (for example) to
-populate. This could be solved on the server by spawning a thread to fetch the
-data, then returning 202 Accepted, which could then be polled client side. Maybe
-this is a better long term approach?
-
 ## Infra / performance
 
 - **HTTP connection pooling.** Parallel server sync in `loadAllPrices`