Temporal Legitimacy Span - The Time-Metric Inside Identity

This paper introduces a structural primitive inside identity: legitimacy span — the bounded amount of temporal displacement a finite agent can carry while continuing to treat the present as legitimate (inhabitable as a basis for continued agency). The account is pre-psychological and non-normative: it does not diagnose persons, prescribe values, or moralize outcomes. It identifies the time-metric implicit in any identity that persists under finitude and irreversible time, derives its collapse geometries, and shows how anchoring determines which changes count as existentially significant. Worked examples are provided separately as illustrative appendices.