Issue 23482 — fixed head 26d95959db; Linux Node v26.12.1.
Only isolated temporary DBs and /home/ubuntu/wt/issue-23482/.t3 were written.

Reporter literal script:
$ node repro-wal-gate.ts worker
checkpointWorker=true: outside reader holds a read transaction
all 1500 writes finished with the reader open (WAL 106.9 MB)

Real server runtime with pinned WAL:
$ node /tmp/issue-23482-pin.cjs
reader pinned; WAL MB 46.289207458496094
This process remained open on a terminal, waiting for a release command. Its read-only
connection had executed BEGIN and SELECT COUNT(*) FROM issue_23482_wal_fixture.
A separate writer had appended 650 x 64 KiB blobs, then closed, leaving the reader open.
$ env -u T3_SERVICE_LAUNCHER_CONTEXT -u T3_BOOT_SERVICE_UNIT node apps/server/src/bin.ts --base-dir /home/ubuntu/wt/issue-23482/.t3 --port 15661 --no-browser
[08:44:20.041] INFO: Listening on http://127.0.0.1:15661
While reader terminal session 85089 remained open (before sending any release):
$ curl --max-time 2 -o /dev/null -w 'HTTP %{http_code}; elapsed %{time_total}s' http://127.0.0.1:15661/api/auth/session
HTTP 200; elapsed 0.010421s
Only AFTER that successful response did lead send 'release' to session 85089:
release
outside reader closed
Stopped server through owned terminal session 44752, exit 130.
No watcher ran. Startup executes database migrations/setup writes; it completed while reader pinned the WAL.

Scope: shared NodeSQLite persistence, no render paths, wire changes, schema changes, provider-specific paths, or client mutations.
Visual fixture matrix empty. Native Electron shell and macOS not exercised; shared server behavior checked on Linux.

Current-head validation: 48b7d20a0b, focused suite 18/18 passing (green-tests.txt).
Source diff confirms production code is unchanged from 26d95959db to 48b7d20a0b; only tests changed.
Server-only exception: visual fixture matrix 0/0; no visible differences.