chore: Simplify shared Roslyn worker lifecycle ownership

[hatayama]

Summary

• The shared Roslyn worker now has one instance-owned session for its process, temporary directory, synchronization lock, and test seams.
• The static host remains the stable orchestration facade without directly owning mutable worker state.

User Impact

• Dynamic code compilation behavior, retry policy, shutdown timing, fallback behavior, and diagnostics are unchanged.
• Worker lifecycle ownership is explicit, reducing the risk of future start, retry, and shutdown paths mutating related state under different locks.

Changes

• Add SharedRoslynCompilerWorkerSession as the single owner of worker process and directory state, synchronization, startup, request I/O, compiler test delegation, and shutdown cleanup.
• Keep the existing SharedRoslynCompilerWorkerHost entrypoints and test facades, delegating through one private ServiceValue.
• Preserve the existing whole-compile lock scope with ExecuteLocked<T> and assert every lock-required session operation with Monitor.IsEntered.
• Extend static facade guards so mutable state cannot move back into the host and the session cannot become a static service.
• Preserve the currently orphaned directory-deleter test seam for behavior-equivalent extraction; its removal is tracked separately as R2-37.
• Add a process-free test that verifies shutdown is idempotent before a worker starts. Real worker lifecycle EditMode tests remain intentionally excluded because PR fix: keep EditMode tests from freezing the editor #942 removed them to prevent Unity Test Runner freezes.

Verification

• Confirmed the static facade guard was Red before extraction on the host's direct lock, request sender, process, and directory state.
• dist/darwin-arm64/uloop compile --project-path <PROJECT_ROOT>: 0 errors, 0 warnings
• SharedRoslynCompilerWorkerHostTests: 15 passed
• ExternalCompilerPathResolverTests: 15 passed
• ExternalCompilerMessageParserTests: 1 passed
• StaticFacadeStateGuardTests: 20 passed
• OnionAssemblyDependencyTests: 83 passed
• Confirmed SharedRoslynCompilerWorkerSession has no dependency on SharedRoslynCompilerWorkerHost.
• No wire-format or protocol-version change

Refs: R2-32 in the Unity CLI Loop refactoring ToDo.

[coderabbitai]

📝 Walkthrough

Walkthrough

Shared Roslyn compiler worker process lifecycle and I/O handling is extracted from SharedRoslynCompilerWorkerHost into a new internal SharedRoslynCompilerWorkerSession class. The host now delegates locking, startup, compile requests, output reading, directory tracking, and shutdown to the session. Tests and static-guard allowlists are updated accordingly.

Changes

Worker Session Extraction

Layer / File(s)	Summary
New SharedRoslynCompilerWorkerSession class Packages/.../SharedRoslynCompilerWorkerSession.cs	Adds a class encapsulating locked process lifecycle: liveness checks, startup, compile request sending, output reading, worker directory recording/cleanup, assembly compilation with test override hooks, graceful/forced shutdown, and lock-assertion.
Host refactored to delegate to session Packages/.../SharedRoslynCompilerWorkerHost.cs	Host adds a ServiceValue field of the new session type and routes TryCompile, readiness checks, assembly building, process startup, compile request/response, directory recording, cancellation/retry shutdown, and test swap hooks through session *Locked methods; removes prior local implementations, the Debug alias, and shutdown-failure logging.
Tests and static-guard allowlist updates Assets/Tests/Editor/DynamicCodeToolTests/SharedRoslynCompilerWorkerHostTests.cs, Assets/Tests/Editor/StaticFacadeStateGuardTests.cs	Adds a test verifying Shutdown is idempotent when the worker was never started, and extends MigratedFacadePaths/InstanceServicePaths allowlists to include the host and session files.

Estimated code review effort: 4 (Complex) | ~60 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Host as SharedRoslynCompilerWorkerHost
  participant Session as SharedRoslynCompilerWorkerSession
  participant Process as Worker Process

  Host->>Session: ExecuteLocked(TryCompileWithRetries)
  Session->>Session: HasLiveProcessLocked()
  alt worker not ready
    Session->>Session: CompileWorkerAssemblyLocked()
    Session->>Process: StartProcessLocked(startInfo)
  end
  Session->>Process: SendCompileRequestLocked(requestFile)
  Session->>Process: GetOutputReaderLocked()
  Process-->>Session: response
  Session-->>Host: compile result
  Host->>Session: ShutdownProcessLocked() (on cancel/retry failure)

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Possibly related PRs

• hatayama/unity-cli-loop#901: Introduces SharedRoslynCompilerWorkerHost and its original tests, which this PR refactors to delegate lifecycle to the new session class.
• hatayama/unity-cli-loop#1156: Removes SharedRoslynCompilerWorkerHostTests.cs entirely, conflicting with this PR's addition of a new test method to the same fixture.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the refactor that moves shared Roslyn worker lifecycle ownership into a session.
Description check	✅ Passed	The description is clearly aligned with the refactor and its tests, so it passes the lenient relevance check.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch refactor/hatayama/extract-shared-roslyn-worker-lifecycle

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[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In
`@Packages/src/Editor/FirstPartyTools/ExecuteDynamicCode/DynamicCompilation/SharedRoslynCompilerWorkerSession.cs`:
- Around line 100-127: The shutdown path in SharedRoslynCompilerWorkerSession
currently exits to the catch blocks on StandardInput failures before reaching
the Kill() fallback, which can leave the worker process orphaned after
_workerProcess is cleared. Refactor the quit/flush/wait logic in the worker
shutdown code so that any IOException, ObjectDisposedException, or
InvalidOperationException from writing
SharedRoslynCompilerWorkerProtocol.SharedCompilerWorkerQuitCommand still falls
through to the kill fallback when workerProcess.HasExited is false, and keep
LogWorkerShutdownFailure as the shared error reporting path.
- Around line 41-45: Dispose any stale cached worker before replacing it in
StartProcessLocked. When ProcessStartHelper.TryStart returns a new process,
check the existing _workerProcess and, if it is non-null and not live according
to HasLiveProcessLocked(), dispose it before assigning the new process handle.
Use the StartProcessLocked and HasLiveProcessLocked methods in
SharedRoslynCompilerWorkerSession to keep the cached process lifecycle correct.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

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Review profile: CHILL

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Run ID: c7f8c80e-ac21-432c-8b67-bf792fad4c0c

📥 Commits

Reviewing files that changed from the base of the PR and between e1eb989 and bca55f5.

⛔ Files ignored due to path filters (1)

• Packages/src/Editor/FirstPartyTools/ExecuteDynamicCode/DynamicCompilation/SharedRoslynCompilerWorkerSession.cs.meta is excluded by none and included by none

📒 Files selected for processing (4)

• Assets/Tests/Editor/DynamicCodeToolTests/SharedRoslynCompilerWorkerHostTests.cs
• Assets/Tests/Editor/StaticFacadeStateGuardTests.cs
• Packages/src/Editor/FirstPartyTools/ExecuteDynamicCode/DynamicCompilation/SharedRoslynCompilerWorkerHost.cs
• Packages/src/Editor/FirstPartyTools/ExecuteDynamicCode/DynamicCompilation/SharedRoslynCompilerWorkerSession.cs

[cubic-dev-ai]

All reported issues were addressed across 5 files

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