Practical Note VI: Fairall 9 as a Regime-Dependent Two-Branch Quantum-Horizon Echo Candidate with a Phase-Ladder Signature

We apply the QHCC two-branch quantum-horizon echo test to the public first-year Swift/LCO continuum light curves of Fairall 9. The analysis uses Swift/UVW2 as the driver and a clean UV/optical response set consisting of Swift UVM2, Swift UVW1, Swift B, Swift V, LCO B, LCO g, LCO V, and LCO r. The primary scan is performed over the black-hole mass range 10⁸--3×10⁸\,M_ using the fixed QHCC branch pair α=2/3 and α=4/3. The full raw campaign gives a strong two-shelf morphology at Mgrid=2.35×10⁸\,M_. The mean selected peaks are $48.00$ h and $96.675$ h, compared with predicted QHCC branch delays of $48.198$ h and $96.396$ h. The branch ratio is $2.014$, both branches contain $8/8$ strict clean-band points, and the inverse timing masses inferred from the two shelves are 2.340×10⁸\,M_ and 2.357×10⁸\,M_, differing by $0.69%$. After second-order polynomial detrending, the two-branch morphology remains present but shifts to a lower preferred mass family, Mgrid=1.67×10⁸\,M_, with mean selected peaks $34.65$ h and $69.375$ h and an inverse-mass mismatch of only $0.11%$. An internal four-segment split shows that Fairall 9 is not stationary in this diagnostic: S1 and S3 support a high-mass family near $(2.5$--2.7)×10⁸\,M_, S4 supports a lower family near 1.2×10⁸\,M_, and S2 is mixed/weak. We therefore interpret Fairall 9 not as a single fixed timing-mass calibrator, but as a regime-dependent two-branch echo candidate. The result is not claimed as a formal detection; it is a reproducible morphology and timing-mass consistency test requiring stronger null tests and the full official segmented data set for confirmation.