OBSL-1025: emit metrics[] in scan-results payload when measurements present

[mivds]

PR chain (soda-core)

1. OBSL-1013: ship table discovery in soda-core (soda data-source discover) #2773 — ship table/column discovery
2. OBSL-1025: emit metrics[] in scan-results payload when measurements present #2774 — emit metrics[] in scan-results payload ← this PR
3. OBSL-1027: SQL AST window functions + UNION-in-CTE #2776 — SQL AST window functions + UNION-in-CTE
4. OBSL-1019/1007 (soda-core part): raw feature-config passthroughs on the dataset-config DTO + MM/dialect seams #2777 — raw feature-config passthrough (config DTO)
5. All-datasource dialect groundwork: time/interval, percentile, typed timestamp literal, NaN filter #2787 — all-datasource dialect groundwork

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Summary

Extends v4's _build_check_collection_results_json_dict to emit a top-level metrics: [...] array — the prerequisite for metric monitoring (OBSL-1008 / OBSL-1024) to send measurements.

• Adds an optional measurement_dicts: list[dict] field to CheckCollectionResult (defaults empty; distinct from the engine-internal measurements: list[Measurement]). MM callers populate it; contracts leave it empty.
• The builder collects measurement dicts across results and adds payload["metrics"] only when at least one is present.
• Byte-identical for contracts: when there are no measurements the "metrics" key is absent entirely (not null, not []), so existing contract payloads are unchanged.

Stacked on #2773 (OBSL-1013). Review/merge that first; this branch targets it.

Test Plan

• Unit: contracts-only payload omits the metrics key; measurements present → metrics: [...] populated
• Regression: full unit suite (986) passes; pre-commit (isort/black/autoflake) clean
• MM tickets (OBSL-1008/1024) will populate measurement_dicts with v3 metric.get_cloud_dict()-shaped dicts

🤖 Generated with Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[m1n0]

Reviewed as a small incremental change to the shared payload builder. No blocking findings. Verified: no pre-existing metrics key in the builder dict, the dataclass field addition is safe (default after defaults), the byte-identical-for-contracts claim holds, and both branches are pinned by tests. CI green.

One robustness point worth a look before the MM PRs build on this:

• payload["metrics"] bypasses to_jsonnable (added after the builder's call). Today that's rescued by an accident: _execute_cqrs_request runs to_jsonnable(request_body) for debug logging (soda_cloud.py:1177), which mutates the body in place before requests serializes it with stock json.dumps. In v3 the metrics dicts were only JSON-safe because the whole body went through JsonHelper.to_jsonnable (cloud/soda_cloud.py:184→223) — get_cloud_dict() values can be Decimal/timedelta/datetime. So an MM caller attaching raw v3-shaped dicts works today only via the logging side effect; anyone making that log line lazy breaks sends. Suggest making it explicit — payload["metrics"] = to_jsonnable(all_measurement_dicts) (and consciously pick remove_null_values_in_dicts, since the accidental pass currently strips nulls inside measurement dicts too) — or pin the "pre-serialised" contract with a test that json.dumps(payload) succeeds with realistic (Decimal/datetime) values.

Nit: getattr(r, "measurement_dicts", None) — the sibling accumulations (post_processing_stages, token_usage) use direct attribute access; the field lives on the base dataclass, so r.measurement_dicts works and won't hide typos.

[mivds]

Both points addressed in 2057a7c:

• metrics serialisation — made explicit: payload["metrics"] = to_jsonnable(all_measurement_dicts), so it no longer relies on the debug-log to_jsonnable side effect mutating the shared list at the send site. Kept remove_null_values_in_dicts at its default True to match the null-stripping the payload dict already gets, and pinned the pre-serialised contract with a json.dumps(payload) test over Decimal/datetime values.
• getattr nit — confirmed measurement_dicts is a declared field on CheckCollectionResult (default_factory=list), so switched to direct r.measurement_dicts like the sibling accumulations.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud