fix(hubs): repair ListCost/ContractedCost for rows without a meter/offer ID

[Michael Flanakin (flanakin)]

🛠️ Description

Fixes defects 2 and 4 from #2214 (defect 1 is #2248; defect 3 is out of scope — see below):

• Defect 2 — cost-repair fallback unreachable without a meter/offer ID. IngestionSetup_v1_0.kql and IngestionSetup_v1_2.kql gated the ListCost/ContractedCost repair fallback behind the same condition as the price-sheet lookup, which requires x_SkuMeterId/x_SkuOfferId. Rows without either — most commonly third-party Marketplace/ISV purchases, which have no Microsoft retail list price by design — never reached the repair fallback, leaving ListCost at 0 despite a real EffectiveCost. That collapses x_TotalSavings and corrupts Effective Savings Rate reporting (negative ESR observed on production hubs in Rows with EffectiveCost but no ListCost produce negative savings rates in the ADX dashboard #2214; reported again independently after an EA→MCA migration in Wrong ESR Calculation after moving from EA to MCA in Rate Optimization #2235).
• Defect 4 — MissingListCost flag doesn't clear after repair. The flag in x_SourceChanges was computed before the repair ran, so a successfully repaired row still reported itself as broken (98.9% of flagged rows on one production hub, per Rows with EffectiveCost but no ListCost produce negative savings rates in the ADX dashboard #2214's data).

Splits the combined gate into two: tmp_MissingCost (no meter/offer ID requirement) now gates entry into the repair fallback; tmp_MissingPrices narrows that further to rows the price-sheet join can actually resolve a key for. A row that's tmp_MissingCost but not tmp_MissingPrices skips the join — all joined columns come back null — and falls through the existing case() blocks' null-safe branches straight to the EffectiveCost-based fallback. That's the same outcome #2214 asked for, and it needed zero new branches in the case() blocks — they already handle the join's no-match case correctly, just weren't reachable for these rows before. MissingListCost is cleared from x_SourceChanges once ListCost is known-good post-repair, in both files.

Scope notes (defect 3 excluded): v1.2 already has x_SourceValues/checkReal provenance tracking, and it automatically picks up newly-repaired rows — old_ListCost is captured before the gate runs, so checkReal('ListCost', old_ListCost, ListCost) downstream correctly detects the change. No new code needed. v1.0's Costs_final_v1_0 schema does not get x_SourceValues and this is intentional, not deferred: v1.0 is kept specifically so people can revert to legacy behavior, and its schema must never gain new columns. Confirmed via a Pester test that asserts x_SourceValues never appears in IngestionSetup_v1_0.kql.

Fixes #2214, #2235
Related: #2286

📷 Screenshots

Not applicable — KQL ingestion transform change, no UI.

📋 Checklist

🔬 How did you test this change?

• 🤏 Lint tests
• 🤞 PS -WhatIf / az validate
• 👍 Manually deployed + verified
• 💪 Unit tests
• 🙌 Integration tests

Added HubsMissingCostGate.Tests.ps1 asserting both KQL files have the gate split, the join is correctly scoped, the merge-back uses the right gate, the MissingListCost clearing logic is present, and v1.0's schema stays frozen. Added MissingCostGateSplit.kql — executable equivalence harness (same pattern as ContractedCostTolerance.kql) covering rows missing one/both IDs, unused spend commitments, non-Microsoft providers, and already-correct prices; verified by hand against the gate logic (PASS = 0 rows on a real Kusto database, not yet run against one). Full PowerShell lint suite passes (3586/3586); full unit test suite passes (2295/2295). Not yet manually deployed or run against a live ingestion pipeline with real cost data — see deploy-to-test below.

📦 Deploy to test?

• Hubs + ADX (managed)
• Hubs + Fabric (manual) — URI:
• Hubs (manual)
• Hubs (no data)
• Workbooks
• Alerts

🙋‍♀️ Do any of the following that apply?

• 🚨 This is a breaking change.
• 🤏 The change is less than 20 lines of code.

📑 Did you update docs/changelog.md?

• ✅ Updated changelog (required for dev PRs)
• ➡️ Will add log in a future PR (feature branch PRs only)
• ❎ Log not needed (small/internal change)

📖 Did you update documentation?

• ✅ Public docs in docs (required for dev)
• ✅ Public docs in docs-mslearn (required for dev)
• ✅ Internal dev docs in docs-wiki (required for dev)
• ✅ Internal dev docs in src (required for dev)
• ➡️ Will add docs in a future PR (feature branch PRs only)
• ❎ Docs not needed (small/internal change)

Internal ingestion-pipeline fix with no user-facing behavior surface beyond the changelog entry — no parameter, template, or public API changed.

Draft — this touches the ingestion pipeline's write path; wants a second pass on the case() fallback behavior for previously-unreachable rows before merging, and a live-data verification run given deploy to test is checked but hasn't actually run yet.

🤖 Generated with Claude Code

[github-actions]

Hubs + ADX (managed) deployed to pr-2290-adx.