Engineering archive

These notes describe work at the date shown. See the usage reference for current behavior.

Combined status-logs wire (PERF 5.4)

Date: 2026-09-10. Base: faf6eff437390dc1f996b498f9fb8aae48c6c83d. Status: implements root protocol-decision.md. Final integrated PROTOCOL_VERSION is 7. PERF does not bump the constant; FLOW owns the dedicated version commit. This track uses the shared constant.

Goal

Replace per-poll host status + two host log-chunk calls with one optional host status-logs call. Keep typed reported_checks on TaskStatus/result (FLOW). Do not scrape display logs to preserve a v6 label.

Host command

New clap subcommand: worker host status-logs (HostOperation::StatusLogs). Existing status and log-chunk stay.

Request (canonical JSON, deny_unknown_fields):

• protocol_version (must equal PROTOCOL_VERSION)
• job_id
• stdout_offset, stdout_limit
• stderr_offset, stderr_limit

Limits use the same caps as log-chunk (MAX_LOG_CHUNK_BYTES).

Response:

• protocol_version
• status (StatusResponse — job, not TaskStatus)
• stdout / stderr (LogChunk)

task-status remains a separate host command. Combined payload does not carry reported_checks.

Mixed-version matrix (root decision)

Direction	Contract
New v7 client → new v7 helper with status-logs	Combined JSON success.
New v7 client → v7 helper without status-logs	Narrow unsupported-command fallback: SSH not 255, empty stdout, stderr matches clap unknown-command for status-logs. Sequential status + two log-chunk for the rest of that follow. Capability is cached per worker identity, not globally on the client.
New v7 client/helper ↔ v6 peer	Existing PROTOCOL_MISMATCH at probe/preflight, before launch/mutate. Intentional upgrade boundary. Document client/helper upgrade together. Not a status-logs fallback success.
New client → broken matching-version helper	Truncated/malformed JSON, permission, auth, or decoded host JSON error: real failure. No fallback.

Do not treat every HOST_REQUEST_FAILED as missing-command. Do not claim v6 wire compatibility. serde(default) is not old-reader compatibility.

Runner behavior

follow_remote tries combined first. On unsupported command (matching protocol only), sequential for the rest of that follow. Preserve byte offsets, terminal two-phase drain/revalidation, cancellation, startup timeout, transport caps. Skip WAIT_POLL when a chunk progressed.

Auth-incident integration (not in this branch)

External draft 71841f8 is withdrawn. Parent is reworking a bounded/streaming signature scan. PERF 5.5 will stream stdout/stderr with a bounded rolling window so a later matcher can scan fixed phrases without allocating 256 MiB. PERF does not implement AgentAdapter::auth_failure_signatures and will not cherry-pick that branch.

SSH multiplexing

Inspect effective ssh -G ControlMaster/ControlPersist/ControlPath only. Do not write user SSH config. Do not invent multiplexing if already effective.