Instruction file imported from ncosentino/pitcrew-dashboard (.github/instructions/genesis/parser-outcomes.instructions.md). Copyright stays with the author.

Parser Outcome and Speculative Probe Rules

Apply these rules when the matching file parses or speculatively probes structured input. An ordinary I/O reader that does not interpret input is outside this instruction's scope.

• Model expected outcomes explicitly, preserving distinctions such as success, no-match, incomplete input, invalid input, unsupported input, and budget exceeded whenever callers respond differently to them.
• Do not use a deliberately thrown exception as a parser branch, backtracking signal, or probe result.
• A speculative probe must either commit or restore every input position, buffered value, diagnostic, budget counter, and terminal disposition it was allowed to change.
• A failed probe must not consume input or leak provisional diagnostics unless that is part of its documented result contract.
• Prefer immutable/local probe state or an explicit snapshot-and-restore boundary over manually reversing individual mutations.
• Catch exception-based framework parsers only at the narrow conversion boundary and translate malformed input into the explicit parser outcome.