feat(synth-overlay): Add Kalshi platform support with real ticker format matching(Closes: #19)

[dev-miro26]

Summary

Extends Synth Overlay to support Kalshi as a second prediction market platform alongside Polymarket. The extension now detects Kalshi pages, scrapes live prices (dollar + cent formats), maps real Kalshi ticker formats to Synth assets/market types, and serves edge data through the existing API server. Includes extension context invalidation guards to prevent errors on extension reload.

Related Issues

Fixes #19

Type of Change

• Improvement to existing tool
• Bug fix
• Documentation

What Changed

Matcher (matcher.py)

• Added _KALSHI_ASSET_MAP with 30+ real Kalshi series tickers (KXBTCD, KXBTC, KXBTC15M, KXETHD, etc.) mapped to assets
• Added _kalshi_series_from_ticker() to extract series from full market tickers (e.g. KXBTCD-26MAR1317-T70499.99 → kxbtcd)
• Short legacy tickers (btc, eth, btcd, ethd) require Kalshi-style date suffix to avoid collision with Polymarket slugs
• Added detect_platform(), asset_from_kalshi_ticker(), get_kalshi_market_type() for Kalshi-specific routing
• normalize_slug() handles multi-segment Kalshi URLs (e.g. /markets/kxsol15m/solana-15-minutes/kxsol15m-26mar121945) and tickers containing periods (e.g. -T70499.99)

Content Script (content.js)

• Added scrapeKalshiPrices() with 4 strategies: cent format ("Yes 52¢"), dollar format ("Yes $0.52"), standalone prices with parent context walk, and order book patterns
• slugFromPage() updated to extract last path segment for deep Kalshi URLs
• Added scanKalshiMarketLinks() to detect crypto market links on Kalshi browse pages
• Added isContextValid() guard + teardown() to prevent "Extension context invalidated" errors — clears polling interval, disconnects MutationObserver, and silences all chrome.runtime calls when extension context dies

Extension (manifest.json, background.js, sidepanel.js)

• Added https://*.kalshi.com/* to host_permissions and content_scripts matches
• background.js: SUPPORTED_ORIGINS includes kalshi.com, null guard on isSupportedUrl()
• sidepanel.js: platform-aware UI labels ("Kalshi" vs "Poly"), Kalshi market link buttons for navigation, updated hint text with real ticker examples

Server (server.py)

• Platform auto-detection from URL parameter via detect_platform()
• Kalshi tickers routed through asset_from_kalshi_ticker() for asset resolution
• Response includes "platform": "kalshi" field

README

• Rewrote Kalshi market matching section with real ticker formats and disambiguation logic
• Updated platform support table (Kalshi: daily, 15min, range)
• Fixed verification URLs and curl examples
• Documented extension context invalidation guard

Testing

• Manually tested
• Tests added/updated

venth-issue-19.mp4

[dev-miro26]

Hi, @e35ventura
I am sorry, I know you are so busy. If you don't mind, could you please review my first PR and leave the feedback kindly?
I appreciate you.

[e35ventura]

It doesn't even work in your demo video? extensions shows kalshi price as 99c to 1c?

[dev-miro26]

It doesn't even work in your demo video? extensions shows kalshi price as 99c to 1c?

bandicam.2026-03-12.21-00-35-853.mp4

@e35ventura
Could you review this video again?
And please leave the feedback kindly.

[ventura-oss]

Closing in favor of #41. PR #41 implements a much more robust Platform Registry architecture and a dynamic grammar parser for Kalshi tickers, which scales significantly better than maintaining a hardcoded list. More importantly, #41 fixes the critical Chrome extension context invalidation bugs on reload and reliably tracks Polymarket balances during SPA navigation. Great effort here, but the structural improvements in #41 make it the preferred path forward.