046: 029's principle 2 put to its breaking experiment on one Pi, the tools and the numbers: an owner (pure-run --store) with shim.so preloaded ships every change its store makes to its files (ops.h: create, write, truncate, allocate, rename, unlink, mkdir), cut at each fsync or fdatasync, over pure link (shipper.c, follower.c), and its sync returns once the follower has the cut (synchronous: one cut in flight, no log); identity: 100,000 messages (200,081 cuts; 34 compactions, an image written again) and 200,000 (400,149 cuts; 67 compactions, a second log segment), the stores compared byte for byte every 1,999 and 3,001 cuts and at the end: 0 differences, the follower's store opened as owner holding every message; takeover: 70 kill -9s (owner alone, the whole node, the node with cuts of 512 and 64 B records): all open, hold every message the owner said done, none not sent, the entries in order (and equal to the owner's own store each time); prefixes: 867 op boundaries of a 100,000-message stream (568 within cuts, 266 around installs) opened as stores: all pass; the price: 204 to 400 us a message on tmpfs (155 us waiting for acks, two cuts a message), 903 bytes shipped a message, 42% of them zeros written ahead (a compaction's new file and the tree's tail)

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diff --git a/research/experiments/046-commit-replica/2026-10-19-identity.jsonl b/research/experiments/046-commit-replica/2026-10-19-identity.jsonl
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+{"run": "identity", "events": 100000, "done": 100000, "owner_exit": 0, "every": 1999, "samples": 100, "samples_differing": 0, "first_differing": [], "end_differences": [], "shim": {"cuts": 200081, "shipped_bytes": 90258606, "waited_ms": 15199.8, "create": [40, 1149], "write": [306989, 88255228], "truncate": [0, 0], "allocate": [1, 24], "rename": [38, 1237], "unlink": [0, 0], "mkdir": [1, 7], "sync": [200081, 2000961], "renamed_to": {"pure.tree": 34, "image-entries": 2, "image-0heard": 1, "image-0sent": 1}}, "shipper": {"cuts": 200081, "records": 200114, "record_bytes": 92059632, "waited_ms": 12018.6, "packets": 228164, "resent": 0}, "follower": {"heard": 200114, "cuts": 200081, "ops": 507150, "op_bytes": 90258606, "received": 228164, "deliveries": 200114, "stored": 200114}, "owner_files": {".writer.lock": 0, "image-0heard": 50, "image-0sent": 60, "image-entries": 655480, "log-0": 8388608, "pure.tree": 1123399}, "follower_opened": {"opened": true, "fault": "none", "total": 100000, "summed": 49975000}}
+{"run": "identity", "events": 200000, "done": 200000, "owner_exit": 0, "every": 3001, "samples": 133, "samples_differing": 0, "first_differing": [], "end_differences": [], "shim": {"cuts": 400149, "shipped_bytes": 178744674, "waited_ms": 43096.0, "create": [74, 2122], "write": [613932, 174738440], "truncate": [0, 0], "allocate": [2, 48], "rename": [71, 2293], "unlink": [0, 0], "mkdir": [1, 7], "sync": [400149, 4001764], "renamed_to": {"pure.tree": 67, "image-entries": 2, "image-0heard": 1, "image-0sent": 1}}, "shipper": {"cuts": 400149, "records": 400215, "record_bytes": 182346609, "waited_ms": 33989.4, "packets": 454929, "resent": 0}, "follower": {"within_cut": false, "heard": 400215, "cuts": 400149, "ops": 1014229, "op_bytes": 178744674, "received": 454929, "deliveries": 400215, "stored": 400215}, "owner_files": {".writer.lock": 0, "image-0heard": 50, "image-0sent": 60, "image-entries": 655480, "log-0": 8388608, "log-1": 8388608, "pure.tree": 1123399}, "follower_opened": {"opened": true, "fault": "none", "total": 200000, "summed": 99950000}}