4 years of failed algos, finally hit something that works!

I've been playing with trading algorithms as a side project for more than 4 years now. Most of that time was spent tinkering with different indicators, losing money on paper, scrapping strategies, a couple of them that made it to live trading, but still lost money, and then starting over. But, it seems that I have finally hit something that works, and I would like some constructive criticism on whether my methodology is sound.

The Setup

The strategy is long only, CNC stocks. The backtest engine is custom python, daily OLHCV dataset, charges modelled (STT, exchange fees, SEBI fees, stamp duty etc). The backtesting results are as follows:

5 Years (Sep 2021 – Sep 2026)

Things I'm aware of:

• The 5Y CAGR is inflated by compounding at scale. The simulated portfolio grows to a lot by year 5, and I am sure I can't deploy that much capital using the strategy without moving prices/slippages. The % numbers are only meaningful at small capital, but enough for retail money.
• The CAGR grows significantly after year 3, which probably points towards survivorship bias, since the universe is based on today's traded assets, and not what was most-traded in 2021.
• The 2Y period (covering the choppy 2024-25 market) is the weakest at 29.9% CAGR. I actually find this reassuring, since this means the system struggled when the market struggled, which is what you'd expect from an honest backtest.

Live Results

I know that backtests don't mean shit, so I put my money where my mouth is, and started trading the strategy live since April. Every trade was tracked manually. The signals are generated by the algorithm, but the trades are executed manually. Zerodha is my broker. Here are some details:

The live run is actually tracking ahead of the backtest. I'm treating that with appropriate skepticism given it's only 4.5 months of data, but I am still increasing capital slowly. I do think that the risk management is executing correctly since the average losing trade is well within the stop threshold.

What I'm Looking for Feedback On

• Backtesting methodology: These result do look a little too promising, so are there frameworks to validate the backtest code/results more formally?.
• What broke your backtested strategy in live trading? I'm more interested in failure patterns than success stories right now.

For anyone still grinding, the process is worth it. I'd be happy to answer questions (well, except the strategy details, obviously)

Disclaimer: Not SEBI registered. Not financial advice. Capital at risk.