Note

Medium Risk
Touches shared @t3tools/contracts error shapes and the core VcsProcess boundary; callers matching on VcsError tags must handle four tags instead of one, though the union alias preserves grouping.

Overview
Replaces the single VcsOutputDecodeError (free-form detail) with four distinct tagged errors: VcsProcessStdinWriteError, VcsProcessOutputReadError, VcsProcessOutputLimitError, and VcsProcessMissingExitCodeError. Each exposes structured fields (stdinBytes, stream, maxBytes, observedBytes) and messages derived from those fields only; real I/O failures keep their underlying cause, while limit and missing-exit-code cases do not invent one.

VcsProcess maps ProcessRunner failures directly to these types instead of factory helpers on the old class. VcsError lists the four tags individually; VcsOutputDecodeError remains as a Schema.Union alias for backward grouping. GitLab CLI’s exhaustive fromVcsError matcher adds cases for each new tag, all falling through to GitLabCliCommandError like before.

Tests add a mocked ProcessRunner path to assert exact cause identity, safe messages, and no synthetic cause on missing exit code.

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Note

Structure VCS process boundary errors into granular error types

• Replaces the single VcsOutputDecodeError class in vcs.ts with four dedicated error classes: VcsProcessStdinWriteError, VcsProcessOutputReadError, VcsProcessOutputLimitError, and VcsProcessMissingExitCodeError, each with structured fields and specific tags.
• Updates VcsProcess.ts to emit these granular types instead of the old VcsOutputDecodeError factory methods, preserving underlying causes for stdin/read failures.
• Updates GitLabCli.ts to map each new error tag to a GitLabCliCommandError with the original cause preserved.
• VcsOutputDecodeError is retained as a union type alias over the four new classes for backward compatibility with existing consumers.
• Behavioral Change: VcsError consumers will now see distinct tags per boundary error type rather than a single generic VcsOutputDecodeError tag.

^{Macroscope summarized a6747ab.}