fix: PlayMode start reports compiler errors instead of timing out

[hatayama]

Summary

• PlayMode start now fails fast with saved compiler diagnostics when Unity reports script compilation errors.
• The CLI returns a structured compiler-error envelope instead of waiting until the PlayMode transition times out.

User Impact

• Before this change, running uloop control-play-mode --action Play with compiler errors could hang until the wait timeout and hide the actual cause.
• After this change, users immediately see the compiler error count and diagnostics, including errors that appear while the CLI is polling for PlayMode to finish starting.

Changes

• Record Unity compiler errors from the editor compilation callbacks for the current editor domain.
• Gate PlayMode start on Unity script-compilation failure state and include saved diagnostics in the tool response.
• Teach the CLI to turn those responses into CONTROL_PLAY_MODE_COMPILE_ERRORS during both the initial request and polling.

Verification

• cli/dist/darwin-arm64/uloop compile --project-path "$(git rev-parse --show-toplevel)"
• cli/dist/darwin-arm64/uloop run-tests --project-path "$(git rev-parse --show-toplevel)" --test-mode EditMode --filter-type regex --filter-value "ControlPlayModeUseCaseTests"
• go test ./internal/cli -run TestRunControlPlayModeWithStateWait
• scripts/check-go-cli.sh
• /Users/a12115/dotfiles/.claude/skills/codex-review/scripts/codex-review v3-beta

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: ae8c79fb-9af6-485f-aa80-42b1d28eb01c

📥 Commits

Reviewing files that changed from the base of the PR and between 2ee34eb and 3d8933e.

⛔ Files ignored due to path filters (5)

• Packages/src/Editor/FirstPartyTools/ControlPlayMode/AssemblyInfo.cs.meta is excluded by none and included by none
• Packages/src/Editor/FirstPartyTools/ControlPlayMode/ControlPlayModeCompilationFailureService.cs.meta is excluded by none and included by none
• Packages/src/Editor/FirstPartyTools/ControlPlayMode/ControlPlayModeCompileError.cs.meta is excluded by none and included by none
• Packages/src/Editor/FirstPartyTools/ControlPlayMode/ControlPlayModeEditorStartup.cs.meta is excluded by none and included by none
• Packages/src/Editor/FirstPartyTools/ControlPlayMode/ControlPlayModeServices.cs.meta is excluded by none and included by none

📒 Files selected for processing (12)

• Assets/Tests/Editor/ControlPlayModeUseCaseTests.cs
• Packages/src/Editor/FirstPartyTools/ControlPlayMode/AssemblyInfo.cs
• Packages/src/Editor/FirstPartyTools/ControlPlayMode/ControlPlayModeCompilationFailureService.cs
• Packages/src/Editor/FirstPartyTools/ControlPlayMode/ControlPlayModeCompileError.cs
• Packages/src/Editor/FirstPartyTools/ControlPlayMode/ControlPlayModeEditorStartup.cs
• Packages/src/Editor/FirstPartyTools/ControlPlayMode/ControlPlayModeResponse.cs
• Packages/src/Editor/FirstPartyTools/ControlPlayMode/ControlPlayModeServices.cs
• Packages/src/Editor/FirstPartyTools/ControlPlayMode/ControlPlayModeUseCase.cs
• Packages/src/Editor/FirstPartyTools/FirstPartyToolsEditorStartup.cs
• cli/internal/cli/control_play_mode_wait.go
• cli/internal/cli/control_play_mode_wait_test.go
• cli/internal/cli/error_envelope.go

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📝 Walkthrough

Walkthrough

Adds compile-error blocking to the play-mode control feature. A new Unity service tracks script compilation failures via pipeline events and snapshots diagnostics. The use case checks compilation state before entering play mode and returns a blocked response with error details. The Go CLI decodes these blocked responses and exits early with a structured error envelope. Tests cover all new paths on both sides.

Changes

Compile-Error Blocking for Control-Play-Mode

Layer / File(s)	Summary
Data contracts: compile error DTO, response fields, Go structs, error code Packages/src/Editor/FirstPartyTools/ControlPlayMode/ControlPlayModeCompileError.cs, Packages/src/Editor/FirstPartyTools/ControlPlayMode/ControlPlayModeResponse.cs, cli/internal/cli/control_play_mode_wait.go, cli/internal/cli/error_envelope.go	ControlPlayModeCompileError sealed class with Message/File/Line and internal factory from CompilerMessage; ControlPlayModeResponse extended with BlockedByCompileErrors, CompileErrorCount, CompileErrors; Go response struct and sub-type mirroring these fields; new errorCodeControlPlayModeCompileErrors constant.
Unity compilation-failure service, registry, and startup wiring Packages/src/Editor/FirstPartyTools/ControlPlayMode/ControlPlayModeCompilationFailureService.cs, Packages/src/Editor/FirstPartyTools/ControlPlayMode/ControlPlayModeServices.cs, Packages/src/Editor/FirstPartyTools/ControlPlayMode/ControlPlayModeEditorStartup.cs, Packages/src/Editor/FirstPartyTools/ControlPlayMode/AssemblyInfo.cs, Packages/src/Editor/FirstPartyTools/FirstPartyToolsEditorStartup.cs	IControlPlayModeCompilationFailureProvider and IControlPlayModeCompilationFailureGate interfaces; ControlPlayModeCompilationFailureService subscribes to Unity compilation events, records errors, snapshots on failure, and clears on next start/success; ControlPlayModeCompilationFailureGate wraps EditorUtility.scriptCompilationFailed; registry and static facade expose them; ControlPlayModeEditorStartup called from FirstPartyToolsEditorStartup.Initialize(); InternalsVisibleTo added for friend assemblies.
ControlPlayModeUseCase compile-error gating Packages/src/Editor/FirstPartyTools/ControlPlayMode/ControlPlayModeUseCase.cs	New constructor with optional IControlPlayModeCompilationFailureProvider and IControlPlayModeCompilationFailureGate parameters; compilation-failure guard inserted in StatusOnly=Play and Play action paths; CreateCompileErrorBlockedResponse helper added; CreateResponse initializes CompileErrors to empty array.
Go CLI compile-error detection and early-exit handling cli/internal/cli/control_play_mode_wait.go	requestControlPlayModeStatus now passes action in payload; initial-response and polling-loop paths check BlockedByCompileErrors and return immediately via controlPlayModeCompileErrorsError; new helper builds cliError with computed count and compile error details.
C# and Go tests Assets/Tests/Editor/ControlPlayModeUseCaseTests.cs, cli/internal/cli/control_play_mode_wait_test.go	Seven new C# tests covering ControlPlayModeCompilationFailureService event-driven state transitions and ControlPlayModeUseCase blocking scenarios (StatusOnly-Play, StatusOnly-Stop, Play with/without saved snapshot), with stub provider/gate helpers; two new Go tests simulate immediate block and mid-poll block, validating exit code, error code, and diagnostics content.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

• hatayama/unity-cli-loop#1312: Modifies runControlPlayModeWithStateWait in the same control_play_mode_wait.go file, adjusting spinner progress callback wiring in the function this PR also extends.
• hatayama/unity-cli-loop#1300: Extends ControlPlayModeResponse and ControlPlayModeUseCase/control_play_mode_wait.go response construction, the same files this PR modifies to add compile-error blocking fields.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 9.52% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'fix: PlayMode start reports compiler errors instead of timing out' directly and clearly describes the main change: fixing PlayMode startup to immediately report compiler errors rather than timing out.
Description check	✅ Passed	The description provides a comprehensive summary of changes related to the changeset, covering the problem (PlayMode start hanging on compiler errors), the solution (fast failure with diagnostics), and the verification approach.
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.

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✨ 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 fix/play-mode

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[cubic-dev-ai]

No issues found across 17 files

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