Discard virtualizer measurement corrections suppressed during an active user gesture instead of replaying stale offsets at scrollend. Preserve post-scroll live anchoring and add unit plus Electron coverage for ordinary scrolling without updates.
Track real user scrolling through scrollend with a quiet watchdog, defer timeline commits and virtualizer corrections until settlement, and make SessionDetail the sole tail-follow owner. Add unit and Electron regressions for scroll writes, reader anchoring, near-tail escape, explicit navigation, and flap timing.
Virtualize SessionDetail rows behind stable presentation boundaries and apply typed incremental patches only after visible commits. Preserve reader state across live updates, handle coalesced and reordered patches, and verify the 120Hz append path with Electron tracing.
Render SessionDetail through measured dynamic-height virtual rows while preserving disclosure state, UUID navigation, reader anchoring, and tail-follow across live updates.
Add focused state/reconciliation tests plus a production Electron harness covering long-session DOM bounds, scrolling performance, offscreen navigation, and live viewport stability.
Implement the full ADR-0006 plan: three-layer separation of transaction
correctness, retry policy, and cross-process writer coordination.
Layer 1 — scripts/tx.ts (transaction correctness):
- runWriteTransaction executes work exactly once; no internal retry.
- BEGIN IMMEDIATE takes the write lock up front (avoids SQLITE_BUSY_SNAPSHOT).
- Guarded rollback: checks inTransaction() via adapter before attempting
ROLLBACK; never masks the primary exception.
- WriteTxDiagnostics attached to errors: phase, code, label,
rollbackSucceeded, rollbackError, transactionActive.
- Binding adapters (betterSqliteTransactionAdapter, nodeSqliteTransactionAdapter)
mapping better-sqlite3's `.inTransaction` and node:sqlite's `.isTransaction`.
- configureConnection centralizes WAL + synchronous + busy_timeout.
Layer 2 — scripts/write-coordinator.ts (retry policy):
- runRetryableWriteTransaction: bounded retry with total time budget.
- Only retries when the transaction confirmed ended (transactionActive=false)
and the error is SQLITE_BUSY during work/commit phase.
- BEGIN-phase BUSY = abort entire build (isBeginBusyFailure); the caller
returns `{ deferred: true, reason: 'writer_busy' }` instead of waiting.
- hasUnusableTransaction detects a still-active transaction after failure;
aborts the build immediately, never retries.
Layer 3 — scripts/writer-lease.ts (cross-process coordination):
- acquireWriterLease: dedicated writer.lock.sqlite with busy_timeout=0 +
BEGIN IMMEDIATE. Non-blocking attempt; bounded wait with retryDelayMs.
- writerLockPathFor derives lock path from the target DB path.
- Lease held for the entire build; released on completion or failure.
- Lock DB uses DELETE journal (not WAL); crash/close auto-releases.
- All consumers obey: skill acquires at build start (returns deferred if
unavailable); app daemon (via worker) acquires for its build cycle.
Build semantics changes:
- affectedSessionIds updated only after successful commit.
- BuildIndexResult gains skipped/skippedFiles for observability.
- Skill finalize failure now fails the build (was silently warned).
- Checkpoint changed to PASSIVE (TRUNCATE reserved for maintenance/exit).
- Skill buildIndex returns { deferred, reason } on lease contention;
indexer-service reschedules the build (deferredRetryMs) without publishing
a heartbeat (so the build-deferred state is visible to cross-process
arbitration).
- Service publishes heartbeat immediately on start() for correct arbitration.
Tests:
- tests/write-transaction.test.mjs: single-shot execution, diagnostics
propagation, auto-rolled-back transaction detected, rollback failure
captured as metadata, BEGIN IMMEDIATE semantics.
- tests/writer-lease.test.mjs: acquire/release, contention returns null,
bounded wait with release during budget.
- tests/app-writer-lease.test.mjs: better-sqlite3 adapter integration.
- tests/app-rollback-guard.test.mjs: rewritten — transient BUSY recovered
by coordinator, persistent BUSY skips file, begin-busy aborts build,
live-transaction aborts build, phantom affectedSessionIds prevented.
- tests/daemon-arbitration.test.mjs: skill defers to fresh app heartbeat,
builds when heartbeat is stale.
- tests/app-indexer-service.test.mjs: new cases for deferred-retry
scheduling and immediate heartbeat on start.
- app/tests/electron-concurrency.mjs + child: dual-child IPC structure for
real better-sqlite3 contention (holder acquires lock → build child starts
→ delayed release → result collected; persistent contention bounded).
ADR-0006 updated to reflect the implemented design.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
tommy0103
