night-shift note: packed-Engram cutover — decode c1 29 → 72-74 t/s

history/night-shifts/2026-09-27.md

@@ -170,3 +170,26 @@ beyond the 30-min readiness budget if the weight load is also cold, so the
 first live serve should use `--no-wait`; the aiden16 manifest flavor is a
 pending format; packed shards cost ~48 GiB/node (fits, but P3's LRU needs
 to know about them).
+
+## P2 live cutover — Mia packed Engram, decode 29 → 72-74 t/s
+
+Cutover executed per operator decision: stop `dsv41-flash-4x-mia` → serve
+with the [[staging]] block (`--no-wait` for the first pass). One bug hit —
+the deployed release binary predated the `out_dir.mkdir` fix, the pack
+aborted on missing dst (fixed by rebuild, serve relaunched; staging
+resumed cleanly, nothing partial written). Pack took ~8 min/node for both
+layers (~50 GiB/node from the NAS snapshot, 4 nodes in parallel); boot log
+confirmed `Exact nvme Engram ... packed=True` for both layers and the
+derived r0 range `[0,96001542)` matched the row-split math exactly.
+Weight load dropped to 1320 s (vs 2060). **Decode c1 probes: 71.9 / 73.8 /
+74.0 tok/s** — 2.5× the unpacked-NAS lane (29 t/s), closing most of the gap
+to Mia's claimed 87.7 (rest is their 87.7-prose probe shape). This is the
+measured proof of the staging thesis: a launcher feature, not a manual
+script, moved a production metric.
+
+Lane state after cutover: `dsv41-flash-4x-mia` live on 4nodes-switch,
+packed engram at `/home/kilork/mia-state/engram` (~50 GiB/node, ledger
+`<dir>/.sm121-staging-engram.json`), `DSV41_PACKED_DIR=/state/engram`.
+Second serves verify-only (sampled row hashes) in ~2 s. Full bench of the
+packed lane is the next measurement (note the harness-bias caveat when
+comparing to the 169/184 EXL3 report).