fix(run-result): replace inlined child envelopes with bounded per-child summaries

[chubes4]

Summary

Parent run_result envelopes no longer inline the full stored run_result of every child job. RunResultEnvelope::fromJobSummary() now emits a bounded per-child summary (job_id, status, counts, outcome class counts) at metadata.datamachine.child_job_summaries, with full child state hydrated by ref via the existing child_run_refs. This keeps fan-out parent engine_data bounded regardless of child count, fixing the engine_data_query_oversize rejections (3.5–4.7 MB parents observed on events.extrachill.com) and reducing multi-MB CAS writes on hot parent rows. Child rows are also fetched once per envelope build instead of twice.

What changed

• inc/Core/RunResultEnvelope.php: removed childJobEnvelopes(); added childJobSummaries() producing bounded per-child summaries (job_id, status, counts, outcome_class_counts) under metadata.datamachine.child_job_summaries, with an int-only counts filter guaranteeing boundedness
• inc/Core/RunResultEnvelope.php: fromJobSummary() now fetches child job rows once and shares them between child_run_refs and child_job_summaries (previously two full child-row loads per terminal envelope build)
• tests/Unit/Core/RunResultEnvelopeChildSummaryTest.php (new): parent with 40 children each holding a ~60KB valid run_result (~2.4MB if inlined) asserts the parent envelope stays within the 163,840-byte validate bound, passes validate(), contains no child_job_envelopes, and carries correct child_run_refs and bounded summaries; runs in the SQLite suite
• tests/Unit/Abilities/Engine/RunFlowAbilityLifecycleTest.php: updated the parent-completion test to assert bounded child_job_summaries and child_run_refs instead of inlined child_job_envelopes

How to test

1. Run homeboy review test data-machine; expect passes as recorded by Cook's deterministic gate.

Compatibility

metadata.datamachine.child_job_envelopes is removed from newly built parent envelopes and replaced by child_job_summaries; a repo-wide grep found no other consumers of child_job_envelopes in inc/ or tests besides the updated test. Previously stored envelopes are untouched (existing valid stored run_results are never migrated, per the established rebuild-on-invalid policy). child_run_refs, outputs.child_jobs totals, and all other envelope fields are unchanged. CHANGELOG/versions untouched (release-owned).

Evidence

• Verified command homeboy review test data-machine: status=succeeded; candidate commit 5ad4cca1d303e651ac7ef98c0e75820891a1259a, tree 67e727e1798e26d7ddd12749b6c7a67f4b4d9aaf, fingerprint cd8a49434dc96299d8327a67c52c2830bf84442ec848bc79965de3aa529b9a1d; durable gate gate-1
• Base unchanged since verification: main remains at 0f03814.
• CI expected: Homeboy CI after push
• Candidate adoption provenance: the candidate was promoted from the recorded Cook task execution.
• Cook deterministic verification: 1 gate(s) completed green.
• Durable run execution: Succeeded
• Reviewer-resolvable evidence from source_refs[0]: fix: parent run_result inlines full child envelopes → multi-MB engine_data rejected as oversize #3637
• Task objective: fix: parent run_result inlines full child envelopes → multi-MB engine_data rejected as oversize #3637
• Verified candidate scope: 3 changed file(s): inc/Core/RunResultEnvelope.php, tests/Unit/Abilities/Engine/RunFlowAbilityLifecycleTest.php, tests/Unit/Core/RunResultEnvelopeChildSummaryTest.php.
• Verified finalization base: main at 0f03814
• deterministic gate passed: sh -c homeboy review test data-machine (Passed)

AI assistance

• AI assistance: Yes
• Tool(s): Homeboy (pi)
• Model: anthropic-claude-fable-5
• Used for: Resolves fix: parent run_result inlines full child envelopes → multi-MB engine_data rejected as oversize #3637: fan-out parent run_result inlining full child envelopes caused multi-MB engine_data writes rejected as engine_data_query_oversize and contributed to EngineData CAS exhaustion.