docs: Add investigation of ElectricSQL freeze after shape handle expiration#1194
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docs: Add investigation of ElectricSQL freeze after shape handle expiration#1194KyleAMathews wants to merge 3 commits intomainfrom
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…ent row
Root cause is a two-layer problem:
1. ElectricSQL Cloud serves stale Cloudflare-cached snapshot after handle expiration
2. state.ts applies Object.assign({}, undefined, partialData) creating incomplete row
The incomplete row (only 5 of ~20 fields) enters the collection and BTree index,
causing the maybeRunGraph while(pendingWork()) loop to not converge properly during
lazy loading for ORDER BY + LIMIT queries.
Documented root cause, code flow analysis, and four recommended fixes.
https://claude.ai/code/session_01MbYMCjmyKh3MdebLHd2ytq
The original notes show NO 409 response. The old handle was already marked expired in ExpiredShapesCache (from a prior session). The expired_handle param is a cache buster but Cloudflare still served stale data (cf-cache-status: HIT, age: 663). This may be related to the stale cache offset bug in electric-sql/electric#3785 where stale responses cause mismatched handle/offset state. https://claude.ai/code/session_01MbYMCjmyKh3MdebLHd2ytq
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🎯 Changes
This PR adds a comprehensive investigation document (
INVESTIGATION-electricsql-freeze.md) that details a critical issue where the application freezes when navigating back to a meeting page after an ElectricSQL shape handle has expired.Problem Summary
The freeze occurs due to a two-layer problem:
ElectricSQL Cloud Stale Cache: When a shape handle expires and reconnects, the initial snapshot may be served from Cloudflare cache (up to 11 minutes stale), missing rows that were created/modified after caching.
TanStack/db Partial Update Without Guard: The
state.tscollection handler applies partial UPDATEs viaObject.assign({}, undefined, partialData)when a row doesn't exist in the current sync session, creating an incomplete row object with only 5 of ~20 expected fields.Root Cause Chain
undefinedstart_timefield (nulls-first ordering)null→false)requestLimitedSnapshot→index.take()must traverse past this entrymaybeRunGraphloop'swhile (pendingWork())repeatedly triggers BTree traversalsInvestigation Includes
cf-cache-status: HIT,age: 663)state.ts(primary fix)maybeRunGraphloop✅ Checklist
🚀 Release Impact
This investigation document serves as a reference for implementing the recommended fixes and understanding the interaction between ElectricSQL's shape caching, partial updates, and TanStack/db's query execution pipeline.
https://claude.ai/code/session_01MbYMCjmyKh3MdebLHd2ytq