[codex] Structure preview session key errors

[juliusmarminge]

Summary

The preview-session atom rejected malformed scoped thread keys with a generic Error. Although the message included the raw key, the failure had no stable tag or structured field, so telemetry and error inspection could not distinguish this invariant from unrelated exceptions without parsing text.

This change replaces that generic throw with a Schema.TaggedErrorClass carrying the malformed threadKey. The message remains the same and is derived from that field. The validation and construction stay inline at the existing failure boundary, avoiding a constructor-only wrapper or an extra helper module.

No behavior test was added for this pure internal-invariant refactor.

Validation

• pnpm vp check (passes with existing repository warnings)
• pnpm vp run typecheck

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Note

Low Risk
Internal error-shape refactor only; same message and failure timing with no auth, data, or API behavior changes.

Overview
Malformed scoped thread keys in previewSessionSyncAtom now throw PreviewSessionThreadKeyParseError (Effect Schema.TaggedErrorClass) with a structured threadKey field instead of a plain Error.

The user-facing message is unchanged; the null check is tightened to threadRef === null. Validation still happens at the same inline boundary in usePreviewSession.ts.

^{Reviewed by Cursor Bugbot for commit 0455679. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Replace generic Error with typed PreviewSessionThreadKeyParseError for invalid preview thread keys

Introduces PreviewSessionThreadKeyParseError, a tagged error class (via effect/Schema) with a structured shape and message, to replace the generic Error thrown when an invalid scoped preview thread key is encountered in previewSessionSyncAtom. Also tightens the invalid key check from a falsy guard to an explicit === null check.

^{Macroscope summarized 0455679.}

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[macroscopeapp]

Approvability

Verdict: Approved

Straightforward error handling refactoring that replaces a plain Error with a structured TaggedErrorClass. The runtime behavior and error message remain unchanged; only the error type is now tagged for better Effect ecosystem integration.

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