Extends the existing dispatch_allow flag (which already injects .dispatch-allow, #43/#51/#53) to also append owner/name to mathias/dispatch's git-tracked dispatch-repos.txt (dispatch#19) — the second of the two required dispatch gates. Being listed there is necessary but not sufficient on its own (the repo still needs its own .dispatch-allow marker) — both are applied independently, neither implies the other, matching dispatch#3's structural trust-zone design where both must say yes. Idempotent: a repo already listed (e.g. dispatch_allow re-requested on resume) is a no-op, not a duplicate line. Failure is reported in its own dispatch_allowlist_failure field, distinct from partial_failure (substitution) and dispatch_allow_failure (the marker file) — the three gates can each fail independently, never conflated (same principle as #51). The allowlist owner/repo/path/branch are hardcoded to match mathias/dispatch's own DISPATCH_ALLOWLIST_* env defaults, confirmed unoverridden in the live CronJob (2026-07-06) before implementing. Tests: fresh registration (existing entries preserved, not clobbered), already-listed no-op (zero writes), allowlist-write failure as a distinct field, dispatch_allow=false never touches the file. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>