#7704: fix(voice-call): add authentication to WebSocket media stream endpoint

## Fix Summary This PR adds authentication to the voice-call WebSocket media stream endpoint, addressing a critical security vulnerability where the endpoint accepted connections without any authentication. **Changes:** - Add `streamToken` config option for URL-based token validation - Add `expectedAccountSid` config option for Twilio accountSid validation - Reject WebSocket upgrades without valid token when `streamToken` is configured - Reject streams with mismatched accountSid when `expectedAccountSid` is configured ## Issue Linkage Fixes #7001 ## Security Snapshot | Metric | Value | |--------|-------| | **Score** | 9.1 / 10.0 | | **Severity** | Critical | | **Vector** | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N | ## Implementation Details ### Files Changed - `extensions/voice-call/src/config.ts` (+11/-0) - `extensions/voice-call/src/media-stream.ts` (+25/-2) - `extensions/voice-call/src/webhook.ts` (+18/-1) ### Technical Analysis This PR adds authentication to the voice-call WebSocket media stream endpoint, addressing a critical security vulnerability where the endpoint accepted connections without any authentication. ## Validation Evidence - Command: `pnpm build` - Status: passed ## Risk and Compatibility non-breaking; compatibility impact was not explicitly documented in the original PR body. ## AI-Assisted Disclosure - AI-assisted: yes - Model: Claude Code <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> This PR adds opt-in authentication/validation around the voice-call media streaming WebSocket endpoint by: - Extending `VoiceCallStreamingConfigSchema` with `streamToken` (query param token gate) and `expectedAccountSid` (Twilio start message validation). - Enforcing the token check during HTTP `upgrade` handling in `extensions/voice-call/src/webhook.ts`, rejecting unauthenticated upgrades. - Validating the Twilio `start.accountSid` inside the stream handler and closing the socket on mismatch. Overall this tightens a previously unauthenticated WS entrypoint. The main concern is that `expectedAccountSid` is stored as mutable handler state, which can cause cross-connection validation races if multiple streams are upgraded concurrently under different expected SIDs. <h3>Confidence Score: 3/5</h3> - Generally safe to merge, but there is a concurrency/state bug risk in the new accountSid validation wiring. - The auth gate on WS upgrades is straightforward and localized, but `MediaStreamHandler.handleUpgrade()` mutates a shared `expectedAccountSid` field that is later used during `start` processing; this can validate against the wrong value under concurrent streams or differing server configuration. `.gitignore` also includes unrelated broad additions that add noise. - extensions/voice-call/src/media-stream.ts (shared mutable expectedAccountSid); .gitignore (unrelated ignore-pattern churn) <!-- greptile_other_comments_section --> _{(3/5) Reply to the agent's comments like "Can you suggest a fix for this @greptileai?" or ask follow-up questions!} <!-- /greptile_comment -->