💭 I'm checking the diff files to see what's been resolved—the CuaDriverNotConfiguredError issue appears to be fixed. Now I need to review the new files in scope to identify any remaining convention violations across the desktop and server implementations. Looking at how errors are being caught in DesktopApp, there's a pattern using Effect.catch with an internal _tag check to branch between different error types. The conventions suggest using Effect.catchTags for statically known tagged failures, which would be cleaner here since the code is discriminating on the tag and building different context based on which error occurred—that's exactly what catchTags is designed for. For the error schemas themselves, CuaDriverConfigurationError has an optional cause field, but looking at where it's actually constructed in CuaDriverServerEnvironment, it always gets a real cause from the toFileUrl mapError. Since the "not configured" case is now handled by a separate error class, the cause should probably be required here to match the convention that every construction wraps a failure. The CuaDriverNotConfiguredError with no fields is fine per conventions. I'm also noticing that replaceCuaDriverServerEnvironment uses Effect.addFinalizer which requires a Scope, and I need to check if that's available in the DesktopApp startup context. There's also the global mutation of process.env which creates hidden state that violates the principle of not hiding dependencies in module globals. Looking at the environment variable handling, I see resolveEmbeddedDriverPath takes process.env as a default parameter and the configuration functions read it directly. There's an Effect-based way to read environment variables, though these are plain functions rather than services so the service-specific conventions don't strictly apply—but the general Effect code conventions still matter. For monitorEmbeddedCuaDriverExit, the Effect.tryPromise approach that catches exceptions and logs warnings looks reasonable. The imports are correct, using the Effect module and the vitest integration. In serverRuntimeStartup, I'm catching errors and logging them with sanitized attributes like binaryPath and the underlying cause, which aligns with the convention about keeping error logging bounded and preserving the exact value only as the cause field. The stringified cause field is borderline acceptable since it's explicitly labeled as cause rather than being mixed into detail or message fields. Using the actual error object would be cleaner, but this is a weak finding. For the error handling pattern, Effect.catch is appropriate here since the entire error channel is intentionally CuaDriverStartError, though the convention suggests using Effect.catchTags even for single known tags — but in DesktopApp's case, the handler branches on _tag checks despite handling the whole channel, which seems inconsistent with the stated convention. Let me verify the actual code at the current commit to confirm what the diff shows. Looking at the DesktopApp region and serverRuntimeStartup, I'm noticing that CuaDriverConfigurationError.cause is marked optional but every place we construct it provides an actual cause. The pattern suggests this should really be required—if every construction wraps a failure, the field shouldn't be optional. This feels like vestigial optionality from an earlier design decision that no longer applies. I'm weighing whether to flag this as a violation. The convention is clear: make cause optional only when the error can legitimately originate without an underlying failure, which isn't the case here. There's only one construction site at line 108, and it always supplies a real cause. It's a minor issue and risks looking like churn from my earlier comment, but it's defensible to call out as inconsistent with the stated convention. Now I'm checking DesktopApp's use of Effect.catch with an inner _tag branch—that should be using Effect.catchTags instead. Let me also verify serverRuntimeStartup's Effect.catch handling and whether startEmbeddedCuaDriver() properly requires Scope for its finalizers. I found an issue in DesktopApp.ts around line 265-274 where Effect.catch is being used with inline _tag discrimination to handle multiple error types. According to the conventions, this should use Effect.catchTags instead, which is the proper way to handle statically known tagged failures—especially when dealing with multiple tags like CuaDriverConfigurationError and CuaDriverNotConfiguredError. Actually, reconsidering: the entire error channel is being handled here, and the tag branching is just for log context, which technically fits the exception case where Effect.catch is acceptable. This feels like a weak violation given the guidance to avoid flagging optional style preferences, so I'm inclined to skip it. Finding B is more concrete: CuaDriverConfigurationError has cause: Schema.optional(Schema.Defect()), but every actual construction provides a real cause value. The optionality forces awkward null-checking at call sites. The convention says cause should be required, and this is a direct issue tied to that rule—even though it contradicts my earlier suggestion in a different context. I'm torn on whether to flag it since it creates churn risk and looks like I'm contradicting myself, but it's textbook per the conventions and would simplify the handler. Let me scan for stronger findings instead. I'm seeing Effect.tryPromise(waitForExit) that logs the cause object directly, which is fine, and startEmbeddedCuaDriver reading process.env directly rather than through an Effect Config service—though that's not really a listed convention violation. The resolveEmbeddedDriverPath default parameter is handled correctly in both test and production paths. I'm also noticing CodexAdapterV2 has similar process.env reads. I'm noticing they're stringifying error causes when logging startup failures in both the desktop and server modules — that violates the convention against copying arbitrary defect text into log payloads; the exact cause value should be preserved as-is rather than converted to a string. The real question is whether item B is actually a violation of the principle that causes should be required when every construction wraps a failure, or if making it optional is justified here. Looking at CuaDriverConfigurationError, it only ever gets constructed with a real cause, so by convention the cause field should be required. Making it optional forces unnecessary defensive checks in DesktopApp like error.cause === undefined. I can post an inline suggestion on line 14 to make cause required, and mention the simplification at the call site as part of that comment. The change is safe — even though DesktopApp would have a dead code path checking for undefined, it still compiles fine since error.cause would be typed as unknown. Now I'm weighing whether this counts as a clear convention violation. The conventions explicitly state optional is only valid when the error can legitimately originate without an underlying failure, which isn't the case here. But there's a chance the author made it optional intentionally for future flexibility, and I might be the one who suggested optional before. To avoid unnecessary churn and stay fair, maybe I should mark this as neutral rather than failure. Actually, rereading the check definition — it says findings lead to failure, and there are findings here. I'll post the comment and mark it as failure. The comment is accurate and improves the code by removing unnecessary undefined handling, so it's worth including. I'll target line 14 in the new CuaDriverServerEnvironment.ts file.

1. modify_pr — One convention finding on the new Cua driver error definitions. See the inline comment.