I4154 — The follow backlog test waits on the follower's cursor, not on fifty milliseconds

○READY wave 0 · p1 · implementation profile · parallel safe

Part of ci-critical-path — The critical path from a change to its verdict, and from a merge to its verified deploy, runs under a minute warm.

Objective

http::follow::tests::a_backlog_beyond_the_bound_in_the_stream_starts_the_client_again writes its backlog only once the follower's cursor stands, and writes it whole, so a loaded runner cannot turn it red.

Why

Train 5's validate 39997497168 failed rust (2) on that test alone (3765 passed, 1 failed): 'never came', with one signal and no stream.resync. run() writes stream.ready (follow.rs:500) before it takes its starting cursor (follow.rs:518, a monitor.stream read under the process-wide PAGE mutex). The test waited for ready plus 50 ms, so on the runner the cursor was taken after two of the three sessions. Every append also advances BLACKBOARD (mesh/journal.rs:1999), so a stalled test thread could split the backlog one signal per round. Train 4's run had passed it: a verdict that depends on the runner's load is a rerun, not a verdict.

Current state

The test waits for any frame and sleeps 50 ms before writing three sessions, each its own change.

Desired state

The follower's heartbeat is 50 ms and the test waits for stream.heartbeat, which only the loop after the cursor writes; the three sessions are written under PAGE's lock, so one round reads them whole. The assertions are unchanged.

Scope

• apps/majordomus-cli/src/http/follow.rs
• .ai/repo/project/issues/I4154.yaml

Out of scope

• Production code, which loses no change (I4155 records the caches' keys)

Dependencies

None. This issue is a root of the graph.

What waits on this

• I4155✕BLOCKED The follower's shared board and page caches are keyed by the repository they read

Acceptance criteria

• The test passes 50 times in a row
• The whole http::follow test module passes

Validation

• bash -c 'for i in $(seq 1 50); do cargo test --manifest-path apps/majordomus-cli/Cargo.toml --lib http::follow::tests::a_backlog_beyond_the_bound_in_the_stream_starts_the_client_again -- --exact || exit 1; done'
• cargo test --manifest-path apps/majordomus-cli/Cargo.toml --lib http::follow::tests

Evidence required

• suite

Evidence

None recorded. Every token above needs a command or an artifact behind it before this issue can be completed; narrative is refused.

Risk

Holding PAGE while writing sessions: open_session never takes PAGE, which is private to follow.rs, so it cannot deadlock.

Timeline

started

—

verified

—

completed

—

Those three fields, the evidence above and the state of the dependencies are all the status is made of. There is no status field to disagree with them.

Canonical record: .ai/repo/project/issues/I4154.yaml. Read it back with majordomus plan show I4154.