bug_healthz_degraded_blocks_ui_engine_subset: /healthz degraded → 503 blocks the UI when running an engine subset

[github-actions]

Problem

/healthz degraded → 503 blocks the UI when running an engine subset

(Auto-created by reconcile-tracking-issues from the planned-feature folder — the
idea.md is the source of detail; run /idea-preflight to verify claims against the
current tree before execution.)

Status

• Stage: IDEA
• Priority: P1

Definition of done

• See the acceptance criteria in the linked idea.md (backfill this checklist at the SPEC stage).

Artifacts

• Idea: docs/00_overview/planned_features/02_mvp2/bug_healthz_degraded_blocks_ui_engine_subset/idea.md

How to execute

Run /idea-preflight, then /pipeline docs/00_overview/planned_features/02_mvp2/bug_healthz_degraded_blocks_ui_engine_subset --auto.

[SoundMindsAI]

Shipped in #559 (squash-merged ad2992a4, 2026-06-18). /healthz is now engine-selection-aware — an excluded engine reports the non-blocking not_selected state instead of unreachable, so a Solr-only stack's UI starts. Operator-path verified live. Folder archived to implemented_features/2026_06_18_bug_healthz_degraded_blocks_ui_engine_subset/.