fix: Launch V2 Unity projects without hanging

[hatayama]

Summary

• V2 projects can now be launched by the native dispatcher instead of waiting for the V3 IPC server.
• Launch reports that Unity opened the project while clearly stating that V2 server readiness was not checked.

User Impact

• uloop launch no longer waits up to ten minutes for a V3 named pipe that V2 projects never create.
• Existing -q and -r process management continues to work for V2 projects.

Changes

• Keep only launch out of V2 CLI delegation; live V2 commands remain delegated.
• Require a UnityLockfile created or updated after the new process begins, and return a structured timeout if it never appears.

Verification

• go test ./... -count=1 from cli/dispatcher
• Repo-local Windows CLI: V2 launch, -q, -r, and forced-stop stale-lockfile relaunch
• scripts/check-go-cli.sh was attempted but Git Bash misreported Windows-path cli/common as containing no Go files; CI will run the authoritative check.

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Review details

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: e578e7d9-cccc-45d6-84e1-64d3dce5cbce

📥 Commits

Reviewing files that changed from the base of the PR and between 45b9ae9 and 00eb247.

📒 Files selected for processing (2)

• cli/dispatcher/internal/dispatcher/launch.go
• cli/dispatcher/internal/dispatcher/launch_unity.go

📝 Walkthrough

Walkthrough

V2 launch commands remain in the native dispatcher. New V2 launch flows wait for a fresh Unity lockfile, skip V3 server readiness probes, and emit V2-specific launch responses with structured timeout handling.

Changes

V2 Native Launch Handling

Layer / File(s)	Summary
Fresh lockfile readiness cli/dispatcher/internal/dispatcher/launch_v2_lockfile.go, cli/dispatcher/internal/dispatcher/launch_v2_lockfile_test.go	Adds polling for post-launch Unity lockfiles, cancellation and timeout handling, and tests for fresh versus stale lockfiles.
V2 launch responses and dependencies cli/dispatcher/internal/dispatcher/launch_deps.go, cli/dispatcher/internal/dispatcher/launch_ready.go	Adds injectable launch timing and lockfile dependencies plus response writers for existing and newly launched V2 projects.
Native V2 launch routing cli/dispatcher/internal/dispatcher/dispatcher_v2_run.go, cli/dispatcher/internal/dispatcher/launch.go, cli/dispatcher/internal/dispatcher/*_test.go	Prevents V2 launch delegation, routes V2 launches through native handling, waits on fresh lockfiles, skips server probes, and validates the resulting responses.

Estimated code review effort: 3 (Moderate) | ~25 minutes

Sequence Diagram(s)

sequenceDiagram
  participant User
  participant Dispatcher
  participant Unity
  participant Lockfile
  User->>Dispatcher: Run V2 launch command
  Dispatcher->>Unity: Start or find Unity process
  Unity->>Lockfile: Update project lockfile
  Dispatcher->>Lockfile: Poll for post-launch modification
  Lockfile-->>Dispatcher: Confirm fresh lockfile
  Dispatcher-->>User: Write V2 project-open response

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Possibly related PRs

• hatayama/unity-cli-loop#1479: Touches the same dispatcher launch dependency-injection plumbing.
• hatayama/unity-cli-loop#1801: Changes V2 dispatcher project detection used by this launch routing.
• hatayama/unity-cli-loop#1807: Intersects with V2 delegation and launch execution-path handling.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: fixing V2 Unity project launch hangs.
Description check	✅ Passed	The description accurately covers the V2 launch flow, lockfile readiness, and process-management behavior.
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 unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/v2-launch-readiness

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🧹 Nitpick comments (1)

cli/dispatcher/internal/dispatcher/launch_v2_lockfile.go (1)

12-15: 📐 Maintainability & Code Quality | 🔵 Trivial | 💤 Low value

Remove unused projectRoot field.

The projectRoot field is never populated or used. The ToCLIError method accurately relies on context.ProjectRoot instead, making this struct field redundant.

♻️ Proposed refactor

 type v2LaunchLockfileTimeoutError struct {
-	projectRoot  string
 	lockfilePath string
 }

🤖 Prompt for 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.

In `@cli/dispatcher/internal/dispatcher/launch_v2_lockfile.go` around lines 12 -
15, Remove the unused projectRoot field from v2LaunchLockfileTimeoutError,
keeping lockfilePath and the existing ToCLIError behavior unchanged.

🤖 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.

Nitpick comments:
In `@cli/dispatcher/internal/dispatcher/launch_v2_lockfile.go`:
- Around line 12-15: Remove the unused projectRoot field from
v2LaunchLockfileTimeoutError, keeping lockfilePath and the existing ToCLIError
behavior unchanged.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 8ec6d996-7c5f-4570-a5a0-49580beb142d

📥 Commits

Reviewing files that changed from the base of the PR and between 1cc123b and 77b257c.

📒 Files selected for processing (8)

• cli/dispatcher/internal/dispatcher/dispatcher_v2_detect_test.go
• cli/dispatcher/internal/dispatcher/dispatcher_v2_run.go
• cli/dispatcher/internal/dispatcher/launch.go
• cli/dispatcher/internal/dispatcher/launch_deps.go
• cli/dispatcher/internal/dispatcher/launch_ready.go
• cli/dispatcher/internal/dispatcher/launch_test.go
• cli/dispatcher/internal/dispatcher/launch_v2_lockfile.go
• cli/dispatcher/internal/dispatcher/launch_v2_lockfile_test.go