Document Firstrade US equity platform support

Author: Pigbibi

docs/platform_repo_boundaries.md

@@ -48,6 +48,7 @@ Examples today:
 - `InteractiveBrokersPlatform`
 - `CharlesSchwabPlatform`
 - `LongBridgePlatform`
+- `FirstradePlatform`
 - `BinancePlatform`
 
 These repositories are the actual deployment units.

docs/us_equity_cross_platform_strategy_spec.md

@@ -2,12 +2,13 @@
 
 ## Goal
 
-All US equity strategies should be written once and be portable across the three
+All US equity strategies should be written once and be portable across the
 current broker runtimes:
 
 - `ibkr`
 - `schwab`
 - `longbridge`
+- `firstrade`
 
 This document defines the contract new strategies must follow, and the migration
 target existing strategies should converge to.
@@ -115,6 +116,7 @@ execution style:
 - `ibkr`: native `weight`
 - `schwab`: native `value`
 - `longbridge`: native `value`
+- `firstrade`: native `value`
 
 Strategies must not implement broker-specific execution transforms themselves.
 
@@ -183,13 +185,14 @@ The platform runtime owns:
 
 The strategy layer must not assume broker-local files or service-specific paths.
 
-## Three-platform support rule
+## Broker-platform support rule
 
 For new US equity strategy profiles, the default expectation is:
 
 - `ibkr` adapter present
 - `schwab` adapter present
 - `longbridge` adapter present
+- `firstrade` adapter present
 
 If one platform is intentionally unsupported, the PR must include an explicit
 reason and the profile must remain `eligible=false` there until the gap is

docs/us_equity_execution_translation_spec.md

@@ -20,12 +20,14 @@ Current native preferences are:
 - `ibkr`: `weight`
 - `schwab`: `value`
 - `longbridge`: `value`
+- `firstrade`: `value`
 
 That means platform runtimes must support these translation paths:
 
 - `weight -> value`
   - needed for `schwab`
   - needed for `longbridge`
+  - needed for `firstrade`
 - `value -> weight`
   - needed for `ibkr`
 
@@ -146,7 +148,7 @@ The blocked reason should appear in platform diagnostics or runtime reports.
 
 - `global_etf_rotation`
   - strategy contract is now `market_history` + `target_mode=weight`
-  - `schwab` / `longbridge` need `weight -> value`
+  - `schwab` / `longbridge` / `firstrade` need `weight -> value`
 - `tqqq_growth_income`
   - strategy contract is now canonical `value`
   - `ibkr` needs `value -> weight`