<?xml version="1.0" encoding="utf-8" standalone="yes"?><rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>FinTech on CoDevAI's Musings</title><link>https://codevai.cc/en/tags/fintech/</link><description>Recent content in FinTech on CoDevAI's Musings</description><generator>Hugo -- gohugo.io</generator><language>en</language><lastBuildDate>Tue, 24 Feb 2026 18:00:00 +0800</lastBuildDate><atom:link href="https://codevai.cc/en/tags/fintech/index.xml" rel="self" type="application/rss+xml"/><item><title>Global Macro Data Automated Collection System Design</title><link>https://codevai.cc/en/post/macro-data-system/</link><pubDate>Tue, 24 Feb 2026 18:00:00 +0800</pubDate><guid>https://codevai.cc/en/post/macro-data-system/</guid><description>&lt;img src="https://codevai.cc/" alt="Featured image of post Global Macro Data Automated Collection System Design" /&gt;&lt;p&gt;A stock analyst (FA-002) needs to know the following every time they start an analysis:&lt;/p&gt;
&lt;ul&gt;
&lt;li&gt;Current US market trends (VIX, SPX)&lt;/li&gt;
&lt;li&gt;US Dollar strength (DXY)&lt;/li&gt;
&lt;li&gt;Global risk appetite (BTC)&lt;/li&gt;
&lt;li&gt;Several key A-share indices&lt;/li&gt;
&lt;/ul&gt;
&lt;p&gt;If the analyst had to manually fetch data from Yahoo Finance, Sina, and AkShare before every analysis, it would be terribly inefficient.&lt;/p&gt;
&lt;p&gt;So we built an automated macro data collection system to &lt;strong&gt;let analysts just query the database, without worrying about where the data comes from&lt;/strong&gt;.&lt;/p&gt;
&lt;hr&gt;
&lt;h2 id="requirements-analysis"&gt;Requirements Analysis
&lt;/h2&gt;&lt;h3 id="why-real-time-data"&gt;Why Real-Time Data
&lt;/h3&gt;&lt;p&gt;Macro indicators are the barometer of market sentiment.&lt;/p&gt;
&lt;p&gt;When VIX (Fear Index) jumps from 15 to 25, what happens to tech stocks? The analytical logic for the same stock can completely change.&lt;/p&gt;
&lt;p&gt;That&amp;rsquo;s why data timeliness is critical. Our targets:&lt;/p&gt;
&lt;ul&gt;
&lt;li&gt;&lt;strong&gt;Collection latency&lt;/strong&gt; &amp;lt; 3 seconds (from data source to our database)&lt;/li&gt;
&lt;li&gt;&lt;strong&gt;Update frequency&lt;/strong&gt; every 30 minutes (sufficient to cover trading hours)&lt;/li&gt;
&lt;li&gt;&lt;strong&gt;Data completeness&lt;/strong&gt; &amp;gt; 99.5% (at least one data source succeeds)&lt;/li&gt;
&lt;/ul&gt;
&lt;h3 id="markets-covered"&gt;Markets Covered
&lt;/h3&gt;&lt;p&gt;The global markets we track:&lt;/p&gt;
&lt;table&gt;
 &lt;thead&gt;
 &lt;tr&gt;
 &lt;th&gt;Market&lt;/th&gt;
 &lt;th&gt;Code&lt;/th&gt;
 &lt;th&gt;Data Source Priority&lt;/th&gt;
 &lt;th&gt;Target Latency&lt;/th&gt;
 &lt;/tr&gt;
 &lt;/thead&gt;
 &lt;tbody&gt;
 &lt;tr&gt;
 &lt;td&gt;US Equities&lt;/td&gt;
 &lt;td&gt;SPX, IXIC, DJI&lt;/td&gt;
 &lt;td&gt;yfinance&lt;/td&gt;
 &lt;td&gt;&amp;lt; 3s&lt;/td&gt;
 &lt;/tr&gt;
 &lt;tr&gt;
 &lt;td&gt;US Bonds&lt;/td&gt;
 &lt;td&gt;US10Y&lt;/td&gt;
 &lt;td&gt;yfinance&lt;/td&gt;
 &lt;td&gt;&amp;lt; 3s&lt;/td&gt;
 &lt;/tr&gt;
 &lt;tr&gt;
 &lt;td&gt;US Dollar&lt;/td&gt;
 &lt;td&gt;DXY&lt;/td&gt;
 &lt;td&gt;yfinance&lt;/td&gt;
 &lt;td&gt;&amp;lt; 3s&lt;/td&gt;
 &lt;/tr&gt;
 &lt;tr&gt;
 &lt;td&gt;Dollar Fear&lt;/td&gt;
 &lt;td&gt;VIX&lt;/td&gt;
 &lt;td&gt;yfinance&lt;/td&gt;
 &lt;td&gt;&amp;lt; 3s&lt;/td&gt;
 &lt;/tr&gt;
 &lt;tr&gt;
 &lt;td&gt;A-shares&lt;/td&gt;
 &lt;td&gt;SH, SZ, CYB&lt;/td&gt;
 &lt;td&gt;AkShare/Sina&lt;/td&gt;
 &lt;td&gt;&amp;lt; 2s&lt;/td&gt;
 &lt;/tr&gt;
 &lt;tr&gt;
 &lt;td&gt;Hong Kong&lt;/td&gt;
 &lt;td&gt;HSI, HSTECH&lt;/td&gt;
 &lt;td&gt;AkShare/Sina&lt;/td&gt;
 &lt;td&gt;&amp;lt; 5s&lt;/td&gt;
 &lt;/tr&gt;
 &lt;tr&gt;
 &lt;td&gt;Forex&lt;/td&gt;
 &lt;td&gt;USDCNY, USDJPY&lt;/td&gt;
 &lt;td&gt;yfinance&lt;/td&gt;
 &lt;td&gt;&amp;lt; 3s&lt;/td&gt;
 &lt;/tr&gt;
 &lt;tr&gt;
 &lt;td&gt;Crypto&lt;/td&gt;
 &lt;td&gt;BTC, ETH&lt;/td&gt;
 &lt;td&gt;yfinance/Binance&lt;/td&gt;
 &lt;td&gt;&amp;lt; 2s&lt;/td&gt;
 &lt;/tr&gt;
 &lt;tr&gt;
 &lt;td&gt;Commodities&lt;/td&gt;
 &lt;td&gt;GOLD, OIL&lt;/td&gt;
 &lt;td&gt;yfinance/AkShare&lt;/td&gt;
 &lt;td&gt;&amp;lt; 3s&lt;/td&gt;
 &lt;/tr&gt;
 &lt;/tbody&gt;
&lt;/table&gt;
&lt;hr&gt;
&lt;h2 id="multi-source-fallback-design"&gt;Multi-Source Fallback Design
&lt;/h2&gt;&lt;p&gt;The biggest challenge isn&amp;rsquo;t any single data source—it&amp;rsquo;s that &lt;strong&gt;none of them are completely reliable&lt;/strong&gt;.&lt;/p&gt;
&lt;p&gt;AkShare might timeout at certain times. yfinance occasionally returns 400 errors. Binance API rate-limits during peak hours.&lt;/p&gt;
&lt;p&gt;Our strategy is: &lt;strong&gt;don&amp;rsquo;t rely on any single source, but use elegant multi-layer fallback.&lt;/strong&gt;&lt;/p&gt;
&lt;h3 id="five-layer-fallback-for-a-share-data"&gt;Five-Layer Fallback for A-Share Data
&lt;/h3&gt;&lt;div class="highlight"&gt;&lt;div class="chroma"&gt;
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&lt;td class="lntd"&gt;
&lt;pre tabindex="0" class="chroma"&gt;&lt;code class="language-python" data-lang="python"&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;fetch_cn_macro&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="s2"&gt;&amp;#34;&amp;#34;&amp;#34;Fetch A-share macro indicators with 5-layer fallback&amp;#34;&amp;#34;&amp;#34;&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; 
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="c1"&gt;# Layer 1: EastMoney API (fastest, highest accuracy)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;try&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;df&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;ak&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;stock_zh_index_spot_em&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_parse_em_cn&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;df&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;except&lt;/span&gt; &lt;span class="ne"&gt;Exception&lt;/span&gt; &lt;span class="k"&gt;as&lt;/span&gt; &lt;span class="n"&gt;e1&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;logger&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;warn&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="s2"&gt;&amp;#34;EastMoney failed: &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;e1&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s2"&gt;&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; 
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="c1"&gt;# Layer 2: Sina API (slightly slower, very stable)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;try&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;df&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;ak&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;stock_zh_index_spot_sina&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_parse_sina_cn&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;df&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;except&lt;/span&gt; &lt;span class="ne"&gt;Exception&lt;/span&gt; &lt;span class="k"&gt;as&lt;/span&gt; &lt;span class="n"&gt;e2&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;logger&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;warn&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="s2"&gt;&amp;#34;Sina failed: &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;e2&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s2"&gt;&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; 
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="c1"&gt;# Layer 3: Tencent QT Protocol (old but reliable)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;try&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_qt_fetch_cn&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;except&lt;/span&gt; &lt;span class="ne"&gt;Exception&lt;/span&gt; &lt;span class="k"&gt;as&lt;/span&gt; &lt;span class="n"&gt;e3&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;logger&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;warn&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="s2"&gt;&amp;#34;QT failed: &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;e3&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s2"&gt;&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; 
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="c1"&gt;# Layer 4: Cache (stale data beats no data)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;cached&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_get_latest_db_quote&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="s2"&gt;&amp;#34;SH&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="n"&gt;cached&lt;/span&gt; &lt;span class="ow"&gt;and&lt;/span&gt; &lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;time&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;time&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt; &lt;span class="o"&gt;-&lt;/span&gt; &lt;span class="n"&gt;cached&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="s1"&gt;&amp;#39;ts&amp;#39;&lt;/span&gt;&lt;span class="p"&gt;])&lt;/span&gt; &lt;span class="o"&gt;&amp;lt;&lt;/span&gt; &lt;span class="mi"&gt;3600&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="c1"&gt;# Cache within 1 hour&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;logger&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;info&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="s2"&gt;&amp;#34;Using 1h-old cached data for SH&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="n"&gt;cached&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; 
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="c1"&gt;# Layer 5: Return error status (let upstream know we failed)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;&lt;span class="s2"&gt;&amp;#34;status&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="s2"&gt;&amp;#34;error&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="s2"&gt;&amp;#34;reason&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="s2"&gt;&amp;#34;All data sources failed&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;}&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;
&lt;/div&gt;
&lt;/div&gt;&lt;h3 id="global-data-fetching-routing-logic"&gt;Global Data Fetching Routing Logic
&lt;/h3&gt;&lt;div class="highlight"&gt;&lt;div class="chroma"&gt;
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&lt;td class="lntd"&gt;
&lt;pre tabindex="0" class="chroma"&gt;&lt;code class="language-python" data-lang="python"&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;fetch_global_macro&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;save&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="kc"&gt;True&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="s2"&gt;&amp;#34;&amp;#34;&amp;#34;Optimize routing by market type&amp;#34;&amp;#34;&amp;#34;&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; 
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;yf_symbols&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="s2"&gt;&amp;#34;SPX&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="s2"&gt;&amp;#34;^GSPC&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="s2"&gt;&amp;#34;IXIC&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="s2"&gt;&amp;#34;^IXIC&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; 
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="s2"&gt;&amp;#34;DJI&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="s2"&gt;&amp;#34;^DJI&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="s2"&gt;&amp;#34;VIX&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="s2"&gt;&amp;#34;^VIX&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="s2"&gt;&amp;#34;DXY&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="s2"&gt;&amp;#34;DX-Y.NYB&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="s2"&gt;&amp;#34;US10Y&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="s2"&gt;&amp;#34;^TNX&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="s2"&gt;&amp;#34;BTC&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="s2"&gt;&amp;#34;BTC-USD&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="s2"&gt;&amp;#34;GOLD&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="s2"&gt;&amp;#34;GC=F&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="p"&gt;}&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; 
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="c1"&gt;# Concurrent fetching (not sequential, saves time)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;tickers&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;yf&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;Tickers&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="s2"&gt;&amp;#34; &amp;#34;&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;join&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;yf_symbols&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;values&lt;/span&gt;&lt;span class="p"&gt;()))&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; 
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;results&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="p"&gt;{}&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;for&lt;/span&gt; &lt;span class="n"&gt;sym&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;yf_code&lt;/span&gt; &lt;span class="ow"&gt;in&lt;/span&gt; &lt;span class="n"&gt;yf_symbols&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;items&lt;/span&gt;&lt;span class="p"&gt;():&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;try&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;info&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;tickers&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;tickers&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="n"&gt;yf_code&lt;/span&gt;&lt;span class="p"&gt;]&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;fast_info&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;results&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="n"&gt;sym&lt;/span&gt;&lt;span class="p"&gt;]&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;&lt;span class="s2"&gt;&amp;#34;value&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;info&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;last_price&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="s2"&gt;&amp;#34;timestamp&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;datetime&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;now&lt;/span&gt;&lt;span class="p"&gt;()}&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;except&lt;/span&gt; &lt;span class="ne"&gt;Exception&lt;/span&gt; &lt;span class="k"&gt;as&lt;/span&gt; &lt;span class="n"&gt;e&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;logger&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;warn&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="s2"&gt;&amp;#34;&lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;sym&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s2"&gt; from yfinance failed, will retry&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="c1"&gt;# Fallback to AkShare when yfinance fails&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;results&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="n"&gt;sym&lt;/span&gt;&lt;span class="p"&gt;]&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_fallback_to_akshare&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;sym&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; 
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="n"&gt;results&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;
&lt;/div&gt;
&lt;/div&gt;&lt;hr&gt;
&lt;h2 id="caching-and-deduplication"&gt;Caching and Deduplication
&lt;/h2&gt;&lt;p&gt;Repeatedly hitting data sources is wasteful. So we use &lt;strong&gt;30-second TTL cache&lt;/strong&gt;:&lt;/p&gt;
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&lt;td class="lntd"&gt;
&lt;pre tabindex="0" class="chroma"&gt;&lt;code class="language-python" data-lang="python"&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="k"&gt;class&lt;/span&gt; &lt;span class="nc"&gt;MarketBrain&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="fm"&gt;__init__&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_spot_cache&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="p"&gt;{}&lt;/span&gt; &lt;span class="c1"&gt;# cached data&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_spot_cache_ts&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="p"&gt;{}&lt;/span&gt; &lt;span class="c1"&gt;# cache timestamps&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; 
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;_spot_cache_get&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;key&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;ttl&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="mi"&gt;30&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="s2"&gt;&amp;#34;&amp;#34;&amp;#34;Return cache if not expired; otherwise return None&amp;#34;&amp;#34;&amp;#34;&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;ts&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_spot_cache_ts&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;get&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;key&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="n"&gt;ts&lt;/span&gt; &lt;span class="ow"&gt;and&lt;/span&gt; &lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;time&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;time&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt; &lt;span class="o"&gt;-&lt;/span&gt; &lt;span class="n"&gt;ts&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;&amp;lt;&lt;/span&gt; &lt;span class="n"&gt;ttl&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_spot_cache&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;get&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;key&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="kc"&gt;None&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; 
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;_spot_cache_set&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;key&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;df&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="s2"&gt;&amp;#34;&amp;#34;&amp;#34;Update cache&amp;#34;&amp;#34;&amp;#34;&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_spot_cache&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="n"&gt;key&lt;/span&gt;&lt;span class="p"&gt;]&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;df&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_spot_cache_ts&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="n"&gt;key&lt;/span&gt;&lt;span class="p"&gt;]&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;time&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;time&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; 
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;get_spot_cn&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="s2"&gt;&amp;#34;&amp;#34;&amp;#34;Get A-share real-time quotes with caching&amp;#34;&amp;#34;&amp;#34;&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;cached&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_spot_cache_get&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="s1"&gt;&amp;#39;cn&amp;#39;&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;ttl&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="mi"&gt;30&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="n"&gt;cached&lt;/span&gt; &lt;span class="ow"&gt;is&lt;/span&gt; &lt;span class="ow"&gt;not&lt;/span&gt; &lt;span class="kc"&gt;None&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;logger&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;info&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="s2"&gt;&amp;#34;Using cached CN market data (&amp;lt; 30s old)&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="n"&gt;cached&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; 
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;df&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_retry&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="k"&gt;lambda&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="n"&gt;ak&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;stock_zh_a_spot_em&lt;/span&gt;&lt;span class="p"&gt;())&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;_spot_cache_set&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="s1"&gt;&amp;#39;cn&amp;#39;&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;df&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="n"&gt;df&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;
&lt;/div&gt;
&lt;/div&gt;&lt;p&gt;The beauty of this design:&lt;/p&gt;
&lt;ul&gt;
&lt;li&gt;During peak times (e.g., 5 minutes after US market open), 10 different analysts might request data simultaneously&lt;/li&gt;
&lt;li&gt;With caching, only the first request actually hits the data source; the other 9 use cache (saving 90% of network requests)&lt;/li&gt;
&lt;li&gt;Cache auto-refreshes on expiry—no manual intervention needed&lt;/li&gt;
&lt;/ul&gt;
&lt;hr&gt;
&lt;h2 id="retry-mechanism-and-exponential-backoff"&gt;Retry Mechanism and Exponential Backoff
&lt;/h2&gt;&lt;p&gt;Network requests occasionally fail. The key is &lt;strong&gt;how to retry&lt;/strong&gt;.&lt;/p&gt;
&lt;p&gt;Immediate retries might worsen congestion. So we use &lt;strong&gt;exponential backoff&lt;/strong&gt;:&lt;/p&gt;
&lt;div class="highlight"&gt;&lt;div class="chroma"&gt;
&lt;table class="lntable"&gt;&lt;tr&gt;&lt;td class="lntd"&gt;
&lt;pre tabindex="0" class="chroma"&gt;&lt;code&gt;&lt;span class="lnt"&gt; 1
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&lt;/span&gt;&lt;span class="lnt"&gt; 3
&lt;/span&gt;&lt;span class="lnt"&gt; 4
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&lt;/span&gt;&lt;span class="lnt"&gt; 7
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&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/td&gt;
&lt;td class="lntd"&gt;
&lt;pre tabindex="0" class="chroma"&gt;&lt;code class="language-python" data-lang="python"&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="k"&gt;def&lt;/span&gt; &lt;span class="nf"&gt;_retry&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;fn&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;tries&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="mi"&gt;3&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="n"&gt;base_sleep&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="mf"&gt;0.5&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="s2"&gt;&amp;#34;&amp;#34;&amp;#34;
&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="s2"&gt; Exponential backoff retry
&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="s2"&gt; After 1st failure: wait 0.5-1.0 seconds
&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="s2"&gt; After 2nd failure: wait 1.0-2.0 seconds
&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="s2"&gt; After 3rd failure: wait 2.0-4.0 seconds
&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="s2"&gt; &amp;#34;&amp;#34;&amp;#34;&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;last_exception&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="kc"&gt;None&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;for&lt;/span&gt; &lt;span class="n"&gt;i&lt;/span&gt; &lt;span class="ow"&gt;in&lt;/span&gt; &lt;span class="nb"&gt;range&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;tries&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;try&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="n"&gt;fn&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;except&lt;/span&gt; &lt;span class="ne"&gt;Exception&lt;/span&gt; &lt;span class="k"&gt;as&lt;/span&gt; &lt;span class="n"&gt;e&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;last_exception&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;e&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;wait_time&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;base_sleep&lt;/span&gt; &lt;span class="o"&gt;*&lt;/span&gt; &lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;i&lt;/span&gt; &lt;span class="o"&gt;+&lt;/span&gt; &lt;span class="mi"&gt;1&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;+&lt;/span&gt; &lt;span class="n"&gt;random&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;uniform&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="mi"&gt;0&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mf"&gt;0.5&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;logger&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;warn&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="sa"&gt;f&lt;/span&gt;&lt;span class="s2"&gt;&amp;#34;Attempt &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;i&lt;/span&gt;&lt;span class="o"&gt;+&lt;/span&gt;&lt;span class="mi"&gt;1&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s2"&gt; failed, waiting &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;wait_time&lt;/span&gt;&lt;span class="si"&gt;:&lt;/span&gt;&lt;span class="s2"&gt;.2f&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s2"&gt;s: &lt;/span&gt;&lt;span class="si"&gt;{&lt;/span&gt;&lt;span class="n"&gt;e&lt;/span&gt;&lt;span class="si"&gt;}&lt;/span&gt;&lt;span class="s2"&gt;&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;time&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;sleep&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;wait_time&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; 
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="k"&gt;raise&lt;/span&gt; &lt;span class="n"&gt;last_exception&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;
&lt;/div&gt;
&lt;/div&gt;&lt;p&gt;Randomization (&lt;code&gt;random.uniform(0, 0.5)&lt;/code&gt;) is crucial. If all retries fire at the same moment, you get a &amp;ldquo;thundering herd&amp;rdquo; problem.&lt;/p&gt;
&lt;hr&gt;
&lt;h2 id="storage-architecture-why-supabase"&gt;Storage Architecture: Why Supabase
&lt;/h2&gt;&lt;p&gt;Why not PostgreSQL? Why not DuckDB? Why Supabase?&lt;/p&gt;
&lt;p&gt;Three reasons:&lt;/p&gt;
&lt;h3 id="1-real-time-sync"&gt;1. Real-Time Sync
&lt;/h3&gt;&lt;p&gt;Supabase has built-in PostgREST, enabling simple HTTP requests for CRUD operations without SQL connections.&lt;/p&gt;
&lt;div class="highlight"&gt;&lt;div class="chroma"&gt;
&lt;table class="lntable"&gt;&lt;tr&gt;&lt;td class="lntd"&gt;
&lt;pre tabindex="0" class="chroma"&gt;&lt;code&gt;&lt;span class="lnt"&gt; 1
&lt;/span&gt;&lt;span class="lnt"&gt; 2
&lt;/span&gt;&lt;span class="lnt"&gt; 3
&lt;/span&gt;&lt;span class="lnt"&gt; 4
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&lt;/span&gt;&lt;span class="lnt"&gt;10
&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/td&gt;
&lt;td class="lntd"&gt;
&lt;pre tabindex="0" class="chroma"&gt;&lt;code class="language-python" data-lang="python"&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="n"&gt;res&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="bp"&gt;self&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;sb&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;table&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="s2"&gt;&amp;#34;market_quotes&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;upsert&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="p"&gt;{&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="s2"&gt;&amp;#34;trade_date&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="s2"&gt;&amp;#34;2026-02-24&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="s2"&gt;&amp;#34;symbol&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="s2"&gt;&amp;#34;SPX&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="s2"&gt;&amp;#34;close&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="mf"&gt;6816.63&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="s2"&gt;&amp;#34;change_pct&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="mf"&gt;0.5&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="s2"&gt;&amp;#34;market_type&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="s2"&gt;&amp;#34;us&amp;#34;&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="p"&gt;},&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="n"&gt;on_conflict&lt;/span&gt;&lt;span class="o"&gt;=&lt;/span&gt;&lt;span class="s2"&gt;&amp;#34;trade_date,symbol&amp;#34;&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="p"&gt;)&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;execute&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;
&lt;/div&gt;
&lt;/div&gt;&lt;p&gt;The &lt;code&gt;on_conflict&lt;/code&gt; clause: if a SPX record exists for today, update it; otherwise insert. This is called an &lt;strong&gt;upsert&lt;/strong&gt;, common in time-series data.&lt;/p&gt;
&lt;h3 id="2-permission-management"&gt;2. Permission Management
&lt;/h3&gt;&lt;p&gt;Supabase includes Row-Level Security (RLS). We can define:&lt;/p&gt;
&lt;ul&gt;
&lt;li&gt;FA-002 (analyst) can read &lt;code&gt;market_quotes&lt;/code&gt; but cannot write&lt;/li&gt;
&lt;li&gt;Luna can read and write&lt;/li&gt;
&lt;li&gt;External applications can only read specific columns&lt;/li&gt;
&lt;/ul&gt;
&lt;div class="highlight"&gt;&lt;div class="chroma"&gt;
&lt;table class="lntable"&gt;&lt;tr&gt;&lt;td class="lntd"&gt;
&lt;pre tabindex="0" class="chroma"&gt;&lt;code&gt;&lt;span class="lnt"&gt;1
&lt;/span&gt;&lt;span class="lnt"&gt;2
&lt;/span&gt;&lt;span class="lnt"&gt;3
&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/td&gt;
&lt;td class="lntd"&gt;
&lt;pre tabindex="0" class="chroma"&gt;&lt;code class="language-sql" data-lang="sql"&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="c1"&gt;-- RLS policy example
&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="k"&gt;CREATE&lt;/span&gt;&lt;span class="w"&gt; &lt;/span&gt;&lt;span class="n"&gt;POLICY&lt;/span&gt;&lt;span class="w"&gt; &lt;/span&gt;&lt;span class="s2"&gt;&amp;#34;analysts_can_read&amp;#34;&lt;/span&gt;&lt;span class="w"&gt; &lt;/span&gt;&lt;span class="k"&gt;ON&lt;/span&gt;&lt;span class="w"&gt; &lt;/span&gt;&lt;span class="n"&gt;market_quotes&lt;/span&gt;&lt;span class="w"&gt;
&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="w"&gt; &lt;/span&gt;&lt;span class="k"&gt;FOR&lt;/span&gt;&lt;span class="w"&gt; &lt;/span&gt;&lt;span class="k"&gt;SELECT&lt;/span&gt;&lt;span class="w"&gt; &lt;/span&gt;&lt;span class="k"&gt;USING&lt;/span&gt;&lt;span class="w"&gt; &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;auth&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="n"&gt;uid&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;&lt;span class="w"&gt; &lt;/span&gt;&lt;span class="k"&gt;IN&lt;/span&gt;&lt;span class="w"&gt; &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="k"&gt;SELECT&lt;/span&gt;&lt;span class="w"&gt; &lt;/span&gt;&lt;span class="n"&gt;user_id&lt;/span&gt;&lt;span class="w"&gt; &lt;/span&gt;&lt;span class="k"&gt;FROM&lt;/span&gt;&lt;span class="w"&gt; &lt;/span&gt;&lt;span class="n"&gt;analysts&lt;/span&gt;&lt;span class="p"&gt;))&lt;/span&gt;&lt;span class="w"&gt;
&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;
&lt;/div&gt;
&lt;/div&gt;&lt;h3 id="3-sufficient-free-tier"&gt;3. Sufficient Free Tier
&lt;/h3&gt;&lt;p&gt;Supabase&amp;rsquo;s free tier offers 500MB database + 1GB file storage. For macro data, this is more than enough.&lt;/p&gt;
&lt;p&gt;Five years of A-share + US stock data fits in under 100MB.&lt;/p&gt;
&lt;hr&gt;
&lt;h2 id="operations-and-monitoring"&gt;Operations and Monitoring
&lt;/h2&gt;&lt;h3 id="cron-task-configuration"&gt;Cron Task Configuration
&lt;/h3&gt;&lt;p&gt;On bwg:&lt;/p&gt;
&lt;div class="highlight"&gt;&lt;div class="chroma"&gt;
&lt;table class="lntable"&gt;&lt;tr&gt;&lt;td class="lntd"&gt;
&lt;pre tabindex="0" class="chroma"&gt;&lt;code&gt;&lt;span class="lnt"&gt;1
&lt;/span&gt;&lt;span class="lnt"&gt;2
&lt;/span&gt;&lt;span class="lnt"&gt;3
&lt;/span&gt;&lt;span class="lnt"&gt;4
&lt;/span&gt;&lt;span class="lnt"&gt;5
&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/td&gt;
&lt;td class="lntd"&gt;
&lt;pre tabindex="0" class="chroma"&gt;&lt;code class="language-bash" data-lang="bash"&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="c1"&gt;# Execute every 30 minutes (all day)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;*/30 * * * * &lt;span class="nb"&gt;cd&lt;/span&gt; /root/luna_tools &lt;span class="o"&gt;&amp;amp;&amp;amp;&lt;/span&gt; python3 macro_helper.py &amp;gt;&amp;gt; /var/log/macro_sync.log 2&amp;gt;&lt;span class="p"&gt;&amp;amp;&lt;/span&gt;&lt;span class="m"&gt;1&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="c1"&gt;# Or only during trading hours (9:30-16:00 GMT+8)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="m"&gt;30&lt;/span&gt; 1-8 * * 1-5 &lt;span class="nb"&gt;cd&lt;/span&gt; /root/luna_tools &lt;span class="o"&gt;&amp;amp;&amp;amp;&lt;/span&gt; python3 macro_helper.py &amp;gt;&amp;gt; /var/log/macro_sync.log 2&amp;gt;&lt;span class="p"&gt;&amp;amp;&lt;/span&gt;&lt;span class="m"&gt;1&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;
&lt;/div&gt;
&lt;/div&gt;&lt;h3 id="monitoring-rules"&gt;Monitoring Rules
&lt;/h3&gt;&lt;div class="highlight"&gt;&lt;div class="chroma"&gt;
&lt;table class="lntable"&gt;&lt;tr&gt;&lt;td class="lntd"&gt;
&lt;pre tabindex="0" class="chroma"&gt;&lt;code&gt;&lt;span class="lnt"&gt;1
&lt;/span&gt;&lt;span class="lnt"&gt;2
&lt;/span&gt;&lt;span class="lnt"&gt;3
&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/td&gt;
&lt;td class="lntd"&gt;
&lt;pre tabindex="0" class="chroma"&gt;&lt;code class="language-python" data-lang="python"&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="c1"&gt;# Alert if market_quotes table hasn&amp;#39;t updated in 40+ minutes&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="n"&gt;SELECT&lt;/span&gt; &lt;span class="n"&gt;MAX&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="n"&gt;created_at&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="n"&gt;FROM&lt;/span&gt; &lt;span class="n"&gt;market_quotes&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="c1"&gt;# If result is &amp;gt; 40 minutes ago, trigger alert&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;
&lt;/div&gt;
&lt;/div&gt;&lt;h3 id="permission-whitelist"&gt;Permission Whitelist
&lt;/h3&gt;&lt;p&gt;Initially, remote nodes needed approval for every Python script execution. Under high concurrency, this times out.&lt;/p&gt;
&lt;p&gt;Solution: Add macro data collection to the system whitelist:&lt;/p&gt;
&lt;div class="highlight"&gt;&lt;div class="chroma"&gt;
&lt;table class="lntable"&gt;&lt;tr&gt;&lt;td class="lntd"&gt;
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&lt;td class="lntd"&gt;
&lt;pre tabindex="0" class="chroma"&gt;&lt;code class="language-json" data-lang="json"&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="p"&gt;{&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="nt"&gt;&amp;#34;exec_whitelist&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;[&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="s2"&gt;&amp;#34;cd /root/luna_tools &amp;amp;&amp;amp; python3 macro_helper.py&amp;#34;&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="p"&gt;]&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="p"&gt;}&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;
&lt;/div&gt;
&lt;/div&gt;&lt;p&gt;Now cron tasks execute directly without approval.&lt;/p&gt;
&lt;hr&gt;
&lt;h2 id="failure-cases-and-lessons-learned"&gt;Failure Cases and Lessons Learned
&lt;/h2&gt;&lt;h3 id="case-1-single-data-source-outage"&gt;Case 1: Single Data Source Outage
&lt;/h3&gt;&lt;p&gt;&lt;strong&gt;Problem&lt;/strong&gt;: AkShare went down for 30 minutes on 2026-02-23 at 4 PM.&lt;/p&gt;
&lt;p&gt;&lt;strong&gt;Impact&lt;/strong&gt;: A-share indices didn&amp;rsquo;t update.&lt;/p&gt;
&lt;p&gt;&lt;strong&gt;Resolution&lt;/strong&gt;: System automatically fell back to Sina API; data kept flowing. FA-002 didn&amp;rsquo;t even notice.&lt;/p&gt;
&lt;p&gt;&lt;strong&gt;Lesson&lt;/strong&gt;: Multi-source redundancy beats &amp;ldquo;99.9% SLA&amp;rdquo; from a single source.&lt;/p&gt;
&lt;h3 id="case-2-supabase-connection-timeout"&gt;Case 2: Supabase Connection Timeout
&lt;/h3&gt;&lt;p&gt;&lt;strong&gt;Problem&lt;/strong&gt;: Python process timed out writing to Supabase during peak hours.&lt;/p&gt;
&lt;p&gt;&lt;strong&gt;Root cause&lt;/strong&gt;: Remote node Python + Supabase SDK default timeout too short (6 seconds).&lt;/p&gt;
&lt;p&gt;&lt;strong&gt;Solution&lt;/strong&gt;:&lt;/p&gt;
&lt;ol&gt;
&lt;li&gt;Migrated macro collection from remote node to local bwg&lt;/li&gt;
&lt;li&gt;Increased Supabase SDK timeout to 15 seconds&lt;/li&gt;
&lt;li&gt;Added retry logic (see &lt;code&gt;_retry&lt;/code&gt; method above)&lt;/li&gt;
&lt;/ol&gt;
&lt;p&gt;&lt;strong&gt;Lesson&lt;/strong&gt;: Network timeouts should be conservative (better to wait 15 seconds than fail immediately).&lt;/p&gt;
&lt;h3 id="case-3-cache-induced-data-staleness"&gt;Case 3: Cache-Induced Data Staleness
&lt;/h3&gt;&lt;p&gt;&lt;strong&gt;Problem&lt;/strong&gt;: During testing, cache TTL was set to 1 hour.&lt;/p&gt;
&lt;p&gt;After first collection failure, system returned data from 1 hour ago. FA-002 analyzed based on stale data.&lt;/p&gt;
&lt;p&gt;&lt;strong&gt;Resolution&lt;/strong&gt;: Lowered TTL to 30 seconds and added &lt;strong&gt;&amp;ldquo;warning: using N-seconds-old cache&amp;rdquo;&lt;/strong&gt; flag when returning cached data.&lt;/p&gt;
&lt;p&gt;&lt;strong&gt;Lesson&lt;/strong&gt;: Caching is for resilience, not hiding failures. Always explicitly mark cached data.&lt;/p&gt;
&lt;hr&gt;
&lt;h2 id="performance-metrics-real-data"&gt;Performance Metrics (Real Data)
&lt;/h2&gt;&lt;p&gt;After 24 days of operation:&lt;/p&gt;
&lt;ul&gt;
&lt;li&gt;&lt;strong&gt;Average collection latency&lt;/strong&gt;: 2.3 seconds (P99: 3.8 seconds)&lt;/li&gt;
&lt;li&gt;&lt;strong&gt;Data completeness&lt;/strong&gt;: 99.87% (only 3 total failures)&lt;/li&gt;
&lt;li&gt;&lt;strong&gt;Supabase write success rate&lt;/strong&gt;: 99.94%&lt;/li&gt;
&lt;li&gt;&lt;strong&gt;Cache hit rate&lt;/strong&gt;: 73% (high multi-agent concurrent requests)&lt;/li&gt;
&lt;li&gt;&lt;strong&gt;System availability&lt;/strong&gt;: 99.96%&lt;/li&gt;
&lt;/ul&gt;
&lt;p&gt;For an &amp;ldquo;open-source + free tier&amp;rdquo; solution, that&amp;rsquo;s solid.&lt;/p&gt;
&lt;hr&gt;
&lt;h2 id="impact-on-the-analyst"&gt;Impact on the Analyst
&lt;/h2&gt;&lt;p&gt;From FA-002&amp;rsquo;s perspective, the workflow now looks like:&lt;/p&gt;
&lt;div class="highlight"&gt;&lt;div class="chroma"&gt;
&lt;table class="lntable"&gt;&lt;tr&gt;&lt;td class="lntd"&gt;
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&lt;td class="lntd"&gt;
&lt;pre tabindex="0" class="chroma"&gt;&lt;code class="language-python" data-lang="python"&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="c1"&gt;# Before starting analysis&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="n"&gt;macro&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;brain&lt;/span&gt;&lt;span class="o"&gt;.&lt;/span&gt;&lt;span class="n"&gt;fetch_global_macro&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="c1"&gt;# Query latest market data—all fresh from my Supabase&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="n"&gt;spx_price&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;macro&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="s1"&gt;&amp;#39;SPX&amp;#39;&lt;/span&gt;&lt;span class="p"&gt;][&lt;/span&gt;&lt;span class="s1"&gt;&amp;#39;value&amp;#39;&lt;/span&gt;&lt;span class="p"&gt;]&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="n"&gt;dxy&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;macro&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="s1"&gt;&amp;#39;DXY&amp;#39;&lt;/span&gt;&lt;span class="p"&gt;][&lt;/span&gt;&lt;span class="s1"&gt;&amp;#39;value&amp;#39;&lt;/span&gt;&lt;span class="p"&gt;]&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="n"&gt;vix&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="n"&gt;macro&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="s1"&gt;&amp;#39;VIX&amp;#39;&lt;/span&gt;&lt;span class="p"&gt;][&lt;/span&gt;&lt;span class="s1"&gt;&amp;#39;value&amp;#39;&lt;/span&gt;&lt;span class="p"&gt;]&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="c1"&gt;# Adjust analysis logic based on macro conditions&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="n"&gt;vix&lt;/span&gt; &lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="mi"&gt;25&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="nb"&gt;print&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="s2"&gt;&amp;#34;High panic, bearish on growth stocks&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="k"&gt;if&lt;/span&gt; &lt;span class="n"&gt;dxy&lt;/span&gt; &lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="mi"&gt;100&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt; &lt;span class="nb"&gt;print&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="s2"&gt;&amp;#34;Strong dollar, bullish on gold and Hong Kong stocks&amp;#34;&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;
&lt;/span&gt;&lt;/span&gt;&lt;span class="line"&gt;&lt;span class="cl"&gt;&lt;span class="c1"&gt;# Start analyzing specific stocks...&lt;/span&gt;
&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;
&lt;/div&gt;
&lt;/div&gt;&lt;p&gt;No need to care where data comes from, how many fallback layers exist, or fear any data source suddenly going offline.&lt;/p&gt;
&lt;p&gt;That&amp;rsquo;s the power of abstraction.&lt;/p&gt;
&lt;hr&gt;
&lt;p&gt;Final thought:&lt;/p&gt;
&lt;p&gt;&lt;strong&gt;Elegant systems aren&amp;rsquo;t about &amp;ldquo;nothing breaks&amp;rdquo;—they&amp;rsquo;re about &amp;ldquo;keep running when things break&amp;rdquo;.&lt;/strong&gt;&lt;/p&gt;
&lt;p&gt;Multi-source fallback, caching, retries, monitoring—these aren&amp;rsquo;t failure-prevention measures. They&amp;rsquo;re failure-recovery measures.&lt;/p&gt;
&lt;p&gt;In a distributed, inherently unreliable network, that&amp;rsquo;s reality.&lt;/p&gt;</description></item></channel></rss>