Expand model tag support: add GLM-5.1, simplify Anthropic IDs, scan tags anywhere in message

- Flink update_bars debouncing
- update_bars subscription idempotency bugfix
- Price decimal correction bugfix of previous commit
- Add GLM-5.1 model tag alongside renamed GLM-5
- Use short Anthropic model IDs (sonnet/haiku/opus) instead of full version strings
- Allow @tags anywhere in message content, not just at start
- Return hasOtherContent flag instead of trimmed rest string
- Only trigger greeting stream when tag has no other content
- Update workspace knowledge base references to platform/workspace and platform/shapes
- Hierarchical knowledge base catalog
- 151 Trading Strategies knowledge base articles
- Shapes knowledge base article
- MutateShapes tool instead of workspace patch

gateway/knowledge/trading/strategies/etfs/leveraged-etfs.md

@@ -0,0 +1,49 @@
+---
+description: "Exploits the negative drift of leveraged ETF pairs by simultaneously shorting both a leveraged ETF and its inverse counterpart tracking the same index, capturing decay from daily rebalancing compounding."
+tags: [etfs, leveraged-etf, letf, short-volatility, decay]
+---
+
+# Leveraged ETFs (LETFs)
+
+**Section**: 4.5 | **Asset Class**: ETFs | **Type**: Short-Volatility / Structural Decay
+
+## Overview
+A leveraged (or inverse) ETF seeks to deliver a fixed multiple (2x, 3x) or the inverse (-1x, -2x, -3x) of the daily return of its underlying index. To maintain the target daily leverage, LETFs must rebalance every day — buying when the market is up and selling when it is down. This daily rebalancing creates a negative drift (volatility decay) in the long run, which can be exploited by shorting both a leveraged ETF and its corresponding leveraged inverse ETF on the same underlying index.
+
+## Construction / Signal
+A leveraged ETF with leverage factor L rebalances daily to maintain L × (daily index return). This requires:
+- **On up days**: Buy more of the underlying index
+- **On down days**: Sell the underlying index
+
+The compounding of daily returns with daily rebalancing creates a path-dependent negative drift over time:
+
+```
+LETF cumulative return < L × (index cumulative return)    [for L > 1 or L < -1]
+```
+
+**Strategy**: Short both a leveraged ETF (e.g., 2x) and its leveraged inverse ETF (-2x) on the same underlying index. Both positions decay in value over time due to daily rebalancing, generating profit from the combined negative drift.
+
+Proceeds from both short positions can be invested in an uncorrelated asset (e.g., a Treasury ETF).
+
+## Entry / Exit Rules
+- **Entry**: Simultaneously short a leveraged ETF (e.g., 2x long) and its corresponding inverse leveraged ETF (e.g., 2x inverse) on the same underlying index.
+- **Exit**: Positions are held as long as both ETFs continue to decay; may require periodic rebalancing of the short pair as relative prices change.
+- **Capital deployment**: Invest the short proceeds into a Treasury ETF or other low-risk asset.
+
+## Key Parameters
+- **Leverage factor**: 2x or 3x (and their -2x or -3x inverses)
+- **Underlying index**: Same index for both the leveraged and inverse leveraged ETF
+- **Rebalancing of short pair**: Periodically rebalance the short positions to maintain equal dollar exposure
+- **Volatility regime**: Decay is larger in high-volatility regimes
+
+## Variations
+- **3x pair**: Short a 3x leveraged ETF and its -3x inverse (higher decay, higher risk)
+- **Single-leg short**: Short only the leveraged (not inverse) ETF when directional bias exists
+- **Volatility regime filter**: Enter positions only in high-volatility environments where decay is expected to be larger
+
+## Notes
+- The negative drift from daily rebalancing is mathematically guaranteed over time for both the leveraged and inverse ETF, making this a structural (not purely alpha-dependent) source of return.
+- **Key risk**: In the short term, if one leg of the short pair (e.g., the inverse ETF) has a large positive return (the market rallies strongly), the short position in the inverse ETF suffers a sizable loss. This short-term risk can be significant even though the long-term drift is negative.
+- The strategy can have a significant downside in the short term if one short leg moves sharply against the position.
+- Transaction costs (borrow costs for short selling LETFs, bid-ask spreads) must be carefully considered; LETF borrow rates can be elevated.
+- Volatility decay is proportional to variance: approximately `L(L-1)/2 × sigma^2` per period for a leverage factor L.