sp500: simplify rebalancer with blended SPY+VEA and 100-stock cap

sp500/Makefile

@@ -1,10 +1,11 @@
 AMOUNT ?= 100000
-TOP ?= 500
+MAX_STOCKS ?= 100
+US_WEIGHT ?= 0.60
 
 .PHONY: build run
 
 build:
 	docker build --pull --rm . -t devbox:latest
 
 run:
-	docker run --rm devbox:latest --amount $(AMOUNT) --top $(TOP)
+	docker run --rm devbox:latest --amount $(AMOUNT) --max-stocks $(MAX_STOCKS) --us-weight $(US_WEIGHT)

sp500/README.md

@@ -1,6 +1,11 @@
 # About
 
-Simple SP500 rebalancer takes the dollar amount to invest and stocks you want to exclude and produces how much of each SP500 stock to buy today.
+Simplified blended rebalancer for **S&P 500 + FTSE Developed (ex-US)**.
+
+Pulls live SPY (S&P 500) and VEA (FTSE Developed Markets ex-US) holdings,
+applies your exclusion list, then caps the buy list to the top N names by
+blended weight (default **100**) so the plan can actually be executed by a
+single trader.
 
 ## Instructions
 
@@ -16,10 +21,29 @@ docker build --pull --rm . -t devbox:latest
 docker run --rm devbox:latest --amount 100000
 ```
 
-With a custom exclusion list and top-N preview:
+Default behaviour: 60% S&P 500 / 40% FTSE Developed ex-US, capped at 100
+holdings, with the built-in exclusion list (TSLA, MSFT, NVDA, INTC, AMD,
+DELL, HPQ, ORCL, PLTR).
+
+Custom exclusion and tighter cap:
+
+```shell
+docker run --rm devbox:latest --amount 100000 \
+  --exclude TSLA,MSFT,NVDA --max-stocks 50
+```
+
+Different US/International split, write a CSV:
+
+```shell
+docker run --rm devbox:latest --amount 100000 \
+  --us-weight 0.7 --csv plan.csv
+```
+
+US-only or International-only:
 
 ```shell
-docker run --rm devbox:latest --amount 100000 --exclude TSLA,MSFT,NVDA --top 20
+docker run --rm devbox:latest --amount 100000 --us-only
+docker run --rm devbox:latest --amount 100000 --intl-only
 ```
 
 ### Debug in VSCode