BE-3541 Single Error Emission

The single-emission migration, previously the top-ranked deferral of BE-3482 Datadog Logs and APM Conformance: flow-step failures are emitted exactly ONCE at the step boundary, with HttpContext carried on the error instead of a second at-site log line. MERGED into develop via MR !571 (squash d1cf9c75 “refactor: emit step errors once by removing the logged-at-site path”, merge commit 1c4c33a5; verified against git 2026-07-22).

For Agents

Since !571, ErrorWithStepStatus.logged_at_site and the logged() constructor are GONE. Always construct with new/message and never error!-log at the detection site; the step boundary emits the single ERROR line. The AGENTS.md section 6.3 “in-flight BE-3541” note is now landed behavior.

What changed

• One ERROR emission per step failure, at the step boundary.
• ErrorWithStepStatus.logged_at_site flag and logged() constructor removed; new/message are the only constructors.
• HttpContext rides the error to the boundary, so http.* fields survive without at-site logging.

What it closes

• BE-3482 deferral 1 (“biggest win” in the ranked list).
• The known limit recorded in Continuation: error.fingerprint activity component (2026-07-13, MR !569 open): at-site-logged variants (e.g. VolueEmsError::ApiError) used to reach the boundary as WARN with no fingerprint at all. With single emission, fingerprint and http.* are emitted for those paths too.

Downstream

• BE-3656 APM Span Enrichment was originally stacked on the pre-merge BE-3541 head dee24ad3; after !571 merged, its MR !578 was rebased zero-conflict onto the post-!571 develop 1c4c33a5.
• Part of the dev throwaway build 1.16.1-feat.2682437891.b7d15e2c (see Dev prototype verification (build b7d15e2c)).
• develop moved on to e2ff6b79 afterwards via the unrelated BE-3685 merge (“feat: generate data point constants and simplify domain generation”).

Related

• BE-3482 Datadog Logs and APM Conformance - the conformance program; this was its deferral 1
• BE-3656 APM Span Enrichment - stacked on this work, now MR !578
• BE-3657 error_stack Adoption - next stage of the error-handling train
• BE-3117 Per-Flow Error Context Store - error-handling redesign lineage
• Agent Context