NAT-376: Prevent Config Properties From Leaking Across View Boundaries

[eugene-mux]

Summary

• Snapshots config properties at view start so mid-view config changes cannot contaminate the current view's events
• Fixes video_source_url (and other config fields) from Video A appearing on Video B's events when the app updates config before calling view="end"
• Adds proper view lifecycle (view="end"/view="start") and video_source_url to the recycled player sample app

Root cause

_createEvent() appends m._configProperties last, intentionally letting customers override any property. But when the app updates config with new video metadata before calling view="end", the config update is processed on the task thread before viewend — so events still in the old view get the new video's metadata.

Fix

Snapshot _configProperties into _viewConfigSnapshot at view start. _createEvent() uses the snapshot instead of the live config. Config changes between views update the snapshot immediately; during an active view the snapshot is frozen. Playback mode changes (ad breaks) are the exception — they update the snapshot mid-view since that's intentional.

Test plan

• Reproduced URL leak on device (Roku 3820X2): playing vid=Mux3 appeared in Mux1's view
• Verified fix: zero mismatches across all events after fix
• Automated stress test (20 rapid transitions): zero crashes, zero mismatches, all transitions 0-1ms
• Manual monkey test (recycled player, 3 videos, rapid random switching): zero crashes, zero mismatches across 11,453 lines of output

🤖 Generated with Claude Code

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Note

Medium Risk
Touches core analytics event construction and view lifecycle handling; mistakes could misattribute events or drop request/heartbeat telemetry during playback transitions.

Overview
Prevents config/video metadata leaking across view boundaries by snapshotting config at viewstart and using that frozen snapshot when building events, while still allowing intentional mid-view updates for player_playback_mode.

Hardens view-transition behavior by (1) ignoring heartbeats when not in a view, and (2) adding hostname-based filtering for stale segment download events using the previous view’s source hostname.

Updates sample apps to better exercise the lifecycle: the recycled player now explicitly sends view="end"/view="start" around content switches and sets video_source_url; the reset player adds a rapid-transition stress test menu item to repeatedly end/start views across alternating streams.

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