WS4: missing-index CREATE statements as copy-paste on Recommendations cards

[erikdarlingdata]

What

Surfaces the SQL Server-suggested CREATE INDEX statement(s) on a MISSING_INDEX Recommendations card as "Copy fix". Previously the card showed advice + Ask-AI but no way to copy the suggested index.

Why it needed shared-library work (not just a reader tweak)

The missing_indexes drill-down (where create_statement lives) is ephemeral — config.analysis_findings has no drill-down column and ReadFinding only rehydrates the built RemediationAction. So the reader never saw the CREATE text. This carries it on the persisted action (FactKey MISSING_INDEX) through the round-trip — exactly the pattern the autogrowth / server-config-memory advisories already use.

Copy-only by design

There is deliberately no handler for MISSING_INDEX — creating an index is a judgement call (over-indexing, write + storage cost), matching the rebuild plan's "advise, over-indexing caveats" stance. So:

• Copy fix ✅ (the CREATE statement)
• Apply ❌ (the reader leaves the card's Remediation null → ShowApply stays false)
• Stays an incident — keeps Open-in-Active-Queries / Ask-AI. A new IsMissingIndexAdvisory flag gates only ShowCopyFix, so the card isn't reclassified.

Changes

Shared (PerformanceMonitor.Analysis / .Notifications)

• RemediationAction: + MissingIndexTarget record + MissingIndexTargets field
• FactRemediation: + BuildMissingIndexAction / ExtractMissingIndexTargets (reads missing_indexes: table / impact / create_statement)
• AlertContext: + MissingIndexTargetDto + ToDto/FromDto round-trip (trailing-optional → backward-compatible)

Dashboard

• AnalysisService: + BuildMissingIndexAction in the build chain
• RecommendationsReader: render the CREATEs as CopyPasteSql, leave Remediation null
• RecommendationItem / RecommendationsViewModel: IsMissingIndexAdvisory → ShowCopyFix

Tests

MissingIndexAdvisoryTests (builder, extractor skip/cap, serializer round-trip, reader copy-only mapping, card affordances) + a MISSING_INDEX copy-only case in RemediationGoldenSampleTests (drill-down → builder drift guard: non-null + targets + not registry-dispatchable). Dashboard.Tests 476 / 0, Lite.Tests 406 / 0.

Scope notes

• Lite + read-only surfaces (email/webhook/MCP) render copy-paste via the shared FactRemediation.GenerateForFinding, which doesn't yet handle MISSING_INDEX — Lite parity is a one-switch-case follow-up, out of scope for this Dashboard-card PR.
• Live verification: the dev servers are well-indexed (no MISSING_INDEX finding fires), so the card won't appear naturally — covered by the round-trip + golden-sample tests instead. Happy to seed a missing-index scenario to demo it end-to-end.

🤖 Generated with Claude Code