feat(AppHost): add WithShowStatsCommand for local dev stats

[mpaulosky]

Closes #261

Working as Sam (Backend/.NET)

Changes

• Added WithShowStatsCommand to MongoDbResourceBuilderExtensions
• Command name: show-myblog-stats, display: 📊 Show MyBlog Stats
• Returns Markdown table of collection document counts via CommandResultData with DisplayImmediately = true
• Empty DB returns *(no collections found)* row with Success = true
• Shared _clearMutex prevents concurrent operations (non-blocking WaitAsync(0))
• Skips system.* collections consistent with clear command
• UpdateState gates on HealthStatus.Healthy → Enabled, else Disabled
• Unit tests: MongoDbStatsCommandTests (5 tests)
• Collection definition: Infrastructure/MongoStatsIntegrationCollection
• Integration tests: MongoShowStatsIntegrationTests (3 tests)
• All 16 prior unit tests continue to pass

[Copilot]

Pull request overview

Adds a new Aspire dashboard operator command for local development to display MongoDB collection document counts (“show-myblog-stats”), along with unit and integration tests in AppHost.Tests.

Changes:

• Registers WithShowStatsCommand in WithMongoDbDevCommands and returns Markdown output via CommandResultData (displayed immediately).
• Implements non-blocking concurrency gating via the shared _clearMutex and skips system.* collections.
• Adds new unit and integration test coverage scaffolding for the stats command.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
src/AppHost/MongoDbResourceBuilderExtensions.cs	Adds WithShowStatsCommand and wires it into the existing MongoDB dev commands pipeline.
tests/AppHost.Tests/MongoDbStatsCommandTests.cs	Adds model-level tests for stats command annotation/state behavior.
tests/AppHost.Tests/MongoShowStatsIntegrationTests.cs	Adds integration tests invoking the new command against a real Aspire+MongoDB container.
tests/AppHost.Tests/Infrastructure/MongoStatsIntegrationCollection.cs	Adds an xUnit collection definition for stats integration tests.

[github-actions]

Test Results Summary

331 tests  +8   330 ✅ +8   19s ⏱️ ±0s
  6 suites ±0     1 💤 ±0 
  6 files   ±0     0 ❌ ±0 

Results for commit 2d0289e. ± Comparison against base commit 924edfc.

♻️ This comment has been updated with latest results.

[codecov]

Codecov Report

❌ Patch coverage is 97.70115% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.57%. Comparing base (924edfc) to head (2d0289e).

Files with missing lines	Patch %	Lines
src/AppHost/MongoDbResourceBuilderExtensions.cs	97.70%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev     #264      +/-   ##
==========================================
+ Coverage   85.56%   86.57%   +1.01%     
==========================================
  Files          44       44              
  Lines         956     1043      +87     
  Branches      115      116       +1     
==========================================
+ Hits          818      903      +85     
- Misses         94       96       +2     
  Partials       44       44              

Files with missing lines	Coverage Δ
src/AppHost/MongoDbResourceBuilderExtensions.cs	94.88% <97.70%> (+1.08%)	⬆️

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[mpaulosky]

❌ Aragorn Review — Changes Required (1 CI Failure)

Failing test: ShowMyBlogStats_Concurrent_Invocations_Allow_Only_One_Run

CI result: AppHost.Tests — 47 passed, 1 failed, 1 skipped.

Error from runner:

Expected results.Count(static r => r.Success) to be 1 because the semaphore
should allow only one stats operation to run at a time, but found 2.
  at MongoShowStatsIntegrationTests.cs:line 96

---

Root cause

The concurrent test calls PrepareAsync(blogPostCount: 0) — an empty database.
The stats handler for an empty DB is essentially instantaneous:

1. Acquires mutex
2. Resolves connection string (already cached in the fixture)
3. ListCollectionNamesAsync → empty cursor, returns in microseconds
4. Builds the one-row empty-table markdown
5. Releases mutex — well before the second Task.WhenAll task has a chance to call WaitAsync(0)

Both tasks succeed → assertion fails.

Compare with ClearMyBlogData_Concurrent_Invocations_Allow_Only_One_Run (passing ✅): it seeds 50 posts + 50 comments + 50 tags = 150 docs before firing two concurrent tasks. That gives the first task real I/O work to do while holding the mutex, so the overlap window exists.

---

Required fix

In MongoShowStatsIntegrationTests.cs, change the concurrent test's arrange step:

// BEFORE — empty DB, first operation completes before second even starts
await PrepareAsync(blogPostCount: 0);

// AFTER — enough documents to hold the mutex open while the 2nd task races
await PrepareAsync(blogPostCount: 50);

One-line fix. The exact count isn't critical; anything that makes the handler do real DB work (network round-trip + document counting) is sufficient.

---

Everything else ✅

Checklist item	Result
File headers on all 3 new .cs files	✅
No .squad/ files in diff	✅
Command name "show-myblog-stats" hardcoded	✅
CommandResultData { Format = Markdown, DisplayImmediately = true }	✅
Empty DB → *(no collections found)* row	✅
system.* collections filtered out	✅
_clearMutex.WaitAsync(0) non-blocking guard reused	✅
IsHighlighted = false (default; unit test verifies)	✅
WithShowStatsCommand wired into WithMongoDbDevCommands	✅
xUnit collection definition follows existing pattern	✅
[Collection("MongoStatsIntegration")] on integration test class	✅
Code style matches existing file	✅
Codecov patch ✅ project ✅ — no coverage decrease	✅
All other 16 CI checks (CodeQL, build, Web/Domain/Arch/Bunit/Integration)	✅

One fix needed, then this is ready to squash-merge. 🎯

— Aragorn, Lead Developer