First controller subscription skips task events published before startup #354

Problem

Subscribe creates a new Redis consumer group at $, the current stream tail. Tasks saved before the first controller subscription are skipped, and the controller has no startup scan to reconcile them.

Reproduction

Save before-start before creating the consumer group. Subscribe the first worker, then save after-start and read its first event.

Observed behavior

The first delivered event is after-start; before-start is skipped. The later event is a positive control showing the reader is functioning.

Expected behavior

Initial controller startup should reconcile already-persisted tasks, either by consuming the backlog or scanning existing records.

Executable regression test

TestReviewSubscriptionDeliversPreexistingTasks (includes fixture in the same file).

git clone --branch test/review-regressions https://github.com/fkautz/ax.git ax-review
cd ax-review
git checkout 1dc2613d29e12f306154a7e1183c1825a55d24ed
go test ./internal/store/redis -run '^TestReviewSubscriptionDeliversPreexistingTasks$' -count=1 -v

Requires the Go toolchain specified by go.mod and redis-server on PATH. The test asserts the desired behavior and fails on the published revision. Production code is unchanged.

The regression uses a real isolated redis-server over a private Unix socket. This concerns first creation of a consumer group; ordinary restarts with an existing group are a separate case.