Address review findings on 01510a8:
1. BLOCKER: sessionRetryBackoff summed to 30min, shorter than the up-to-
~60min gap between a session dying and the next hourly SYB sync
refreshing it. Changed to 5m/10m/15m/30m/30m (total 90min across
maxSessionRetryAttempts=6), updated the code comment to state the
~90min > one hourly sync period rationale, and added
TestSessionRetryBackoffTotalExceedsHourlySyncWindow to guard it.
2. Test gap: the CheckSession probe added inside
restoreOrderWritebackClient was only exercised through a fake
Factory, never through a real sybclient.Client. Added
httptest-backed tests that run restoreOrderWritebackClient against
an emulated /am/user/get (matching the envelope shape in
sybclient/client.go's `envelope` type): valid session returns a
client, mismatched username maps to ErrSessionInvalid, 5xx/timeout
map to a non-invalid error — each asserting the syb_session row is
left untouched. Added an end-to-end worker test using the real
Factory against the invalid-session server, asserting
failed/SYB_SESSION_UNAVAILABLE with a scheduled backoff and an
intact session row.
3. sessionUnavailableMessage: renamed the default category to
"会话恢复失败（网络/其他）" and wrapped every category in an
actionable template ("SYB会话不可用（<类别>），将自动重试；如持续
失败请恢复登录后重试"), still well under the 300-char column limit
and free of raw error text/credentials.
Tests: go vet ./app/goauto/purchase/... (clean); go test
./app/goauto/purchase/... (ok, 3.4s, includes the new httptest-backed
CheckSession coverage and the backoff-window guard).
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NTDbDcwbDw1TSAcE6wfh2F
