Share Grace.Server restart scenarios

[ScottArbeit]

Share Grace.Server restart scenarios

Related to Issue #1026.

Why

Five ordinary resilience scenarios each restarted Grace.Server independently. They can retain the same behavior checks across one deliberate restart, shortening the broad validation path without changing product behavior.

What changed

• Split Agent Session, Approval, Webhook, and durable-actor restart flows into typed preparation and post-restart scenario functions.
• Add one explicit single-instance, nonparallel fixture that prepares all contexts against the same server process.
• Perform one observed Grace.Server restart with fresh non-ready, Healthy, HTTP-ready, and /healthz checks.
• Keep five separately named post-restart tests for clear scenario-level failures.
• Remove the four redundant ordinary restart calls.

No production, Aspire helper, project, validation workflow, WDU, persistence, public contract, generated, or measurement path changed.

Validation

• Release build: 0 warnings, 0 errors
• Focused shared fixture: 5/5 passed
• Focused test time: 49.69 seconds
• Ordinary restart-call inventory across the four owned files: exactly one
• Existing separate Manifest Contribution Accounting restart remains [<Explicit>]
• Fantomas and git diff --check: clean

The applicable baseline Validate run used unchanged relevant inputs, reported 284 passing Grace.Server.Tests in 4m52s, and logged five ordinary restarts. The focused Windows timing is not directly comparable; current-head GitHub Validate will provide the comparable assembly result.

Delivery

• Base: epic/835-working-directory-update
• Candidate head: 12ae257255c711622c76561844da6dfe4e2b2b53
• Candidate tree: 69b6bcb388bd94115a662128e413b2c734fc3468
• Docs impact: none
• Skipped: local Fast/Full; required GitHub Validate, Shape Review, and R1 are controller-owned
• Concurrent work: Issue WDU-10: Retire superseded paths and complete the contract audit #846 has a disjoint WDU CLI/docs write set. Landing is serialized; the second candidate will refresh and revalidate against the first merge.

[ScottArbeit]

Review and validation complete

Pinned head: 12ae257255c711622c76561844da6dfe4e2b2b53

• Shape Review: completed with material shape changes, zero owner questions, and passing layout checks at 1440, 1024, and 768 CSS pixels.
• R1 verdict: PASS, no findings and no accepted risks.
• Current-head GitHub Validate: passed, run 32912574561.
• Grace.Server.Tests: 284 passed in 3m28s, compared with 4m52s on the applicable baseline run.
• Runtime evidence: one ordinary shared restart context instead of five, with the same 284 passing tests.
• Focused local fixture: 5/5 passed.
• Release build, Fantomas, and git diff --check: clean.
• Scope: four declared server-test files only; no production, helper, project, validation, WDU, contract, persistence, or generated change.

The one-sample timing supports the intended reduction but is not a performance guarantee.

PR #1028 is ready for owner approval at the pinned head. It has not been merged.