WS3: percent-autogrowth-on-large-files config recommendation

[erikdarlingdata]

Scope

First WS3 catalog fact for the recommendations-engine rebuild: a percent-autogrowth-on-large-files config recommendation. Flags data/log files that are large (total_size_mb >= 10240, i.e. 10 GB) AND on PERCENTAGE autogrowth (is_percent_growth = 1) — a % growth on a big file is a single huge allocation that stalls writes — and recommends switching to a size-tiered fixed-MB FILEGROWTH. System DBs (master/msdb/model/tempdb) excluded; both data and log files included (labelled by file_type_desc).

Advise + copy-paste ONLY this PR — no Apply. No handler is registered for the FILE_AUTOGROWTH_PERCENT fact key, so HasHandlerFor returns false → no Apply button, no destructive-consent path. The fact mirrors the existing DB_CONFIG config-advisory pattern end to end.

Size tiers for the suggested fixed FILEGROWTH: 256 MB (10–50 GB), 512 MB (50–200 GB), 1024 MB (> 200 GB) — a starting point the advice tells the operator to tune.

File:line changelog

Shared analysis (PerformanceMonitor.Analysis)

• RemediationAction.cs:36 — FileGrowthTargets trailing optional ctor param; :147 new FileGrowthTarget record (advisory-only carrier).
• FactScorer.cs:36 — "config" dispatch arm; :246 ScoreConfigFact (base 0.3 for FILE_AUTOGROWTH_PERCENT when file_count > 0, 0 otherwise; every other config-source fact still scores 0).
• InferenceEngine.cs:40 — FILE_AUTOGROWTH_PERCENT added to ConfigAdvisoryRootKeys (roots standalone at 0.3).
• FactAdvice.cs:428 — authored t["FILE_AUTOGROWTH_PERCENT"] AdviceBlock (Headline "Large file(s) growing in percentage steps").
• FactRemediation.cs:42 GenerateForFinding arm; :107 BuildFileAutogrowthAction; :617 ExtractFileGrowthTargets; :668 GenerateForFileAutogrowth; :686 RecommendedGrowthMbFor (tier); :700 BuildModifyFileStatement (shared QUOTENAME renderer).

Notifications (PerformanceMonitor.Notifications)

• AlertContext.cs:86 RemediationActionDto.FileGrowthTargets; :150 FileGrowthTargetDto; ToDto/FromDto branches so the advisory action round-trips through remediation_action_json.

Dashboard

• Analysis/SqlServerFactCollector.cs:50 pipeline wire; :1551 CollectFileAutogrowthFactsAsync (reads collect.database_size_stats, parameterized @minSizeMb).
• Analysis/SqlServerDrillDownCollector.cs:58 pre-0.5-gate dispatch; :806 CollectAutogrowthPercentFiles (emits autogrowth_percent_files with per-file detail + alter_statement via the shared renderer, TOP (50)).
• Analysis/AnalysisService.cs:171 ?? BuildFileAutogrowthAction(finding) in the action-build chain.
• Services/Recommendations/RecommendationsReader.cs:250 BuildCopyPasteFromAction renders MODIFY FILE from FileGrowthTargets (SettingFromAction already returns None → never de-dupes).
• Mcp/McpAnalysisTools.cs:456 next-tool map entry.

Lite (advise/copy-paste only; drill-down is the fix surface — no action persisted)

• Analysis/DuckDbFactCollector.cs:50 pipeline wire; :1446 CollectFileAutogrowthFactsAsync (reads database_size_stats, $1 server filter).
• Analysis/DrillDownCollector.cs:56 pre-0.5-gate dispatch; :846 CollectAutogrowthPercentFiles (reads v_database_size_stats).
• Analysis/TestDataSeeder.cs:1819 SeedPercentAutogrowthFilesAsync (test helper).
• Mcp/McpAnalysisTools.cs:792 next-tool map entry.

Tests

• Dashboard.Tests/FactScorerTests.cs — scorer 0.3-when-files / 0-when-none, advice-block-exists.
• Dashboard.Tests/InferenceEngineTests.cs — FileAutogrowthPercentFact_RootsStandalone_BelowMinimumSeverity.
• Dashboard.Tests/RecommendationDeduperTests.cs — BuildCopyPasteFromAction MODIFY FILE rendering + MapEngineFinding carries copy-paste / Setting == None.
• Dashboard.Tests/AnalysisNotificationTests.cs — build-from-drill-down + SerializeAction/DeserializeAction round-trip.
• Lite.Tests/FactCollectorTests.cs — collector emission smoke tests (qualifying-only; absent-when-none) against the real DuckDB schema.

Test counts (real, --no-build)

• Dashboard.Tests: 324 passed, 0 failed, 0 skipped.
• Lite.Tests: 362 passed, 0 failed, 0 skipped. (the order-dependent AzureAuthConnectionStringTests.UpdateServer_ServicePrincipalToEntraMfa_BlankUsername_DeletesOrphanedSecret passed in-suite this run.)
• dotnet build PerformanceMonitor.sln -c Debug: 0 warnings, 0 errors.

Needs integration verification (live server, e.g. sql2022)

The SQL collection + drill-down need a server with a real large percent-growth file; not exercised by the unit suite:

1. CollectFileAutogrowthFactsAsync actually emits the FILE_AUTOGROWTH_PERCENT fact on a server whose collect.database_size_stats has a >= 10 GB file with is_percent_growth = 1 in a user DB.
2. The finding surfaces (roots at 0.3) and the autogrowth_percent_files drill-down lists the file(s) with a valid copy-paste ALTER DATABASE ... MODIFY FILE statement.
3. The persisted advisory action round-trips through config.analysis_findings.remediation_action_json and the Recommendations reader's CopyPasteSql carries the MODIFY FILE text on read.
4. No Apply affordance appears for the finding (advisory only).

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