Seven arrows, 429 trees: a seven-year naming mistake that surfaced during cleanup of Mermaid visualization

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This article examines a seven-year-old naming mistake in the turing-machine-js project that surfaced during Mermaid visualization cleanup. The core issue involves a halt-state override API whose naming and behavior created confusing nested state names and misleading call traces. The piece walks through the bug, its impact on generated diagrams, and the reasoning behind the corrected API design in v7. It also highlights a rename from withOverrodeHaltState to withOverriddenHaltState to better reflect past-tense semantics and reduce ambiguity for developers. The update is most relevant to JavaScript library maintainers and teams working with developer tooling or state-machine abstractions.

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