docs + guard: single 262k slot state, split-limits analysis, cache incident

- spec matrix + PP doc: production state = 1 slot @ 262144, split 0.53
  (34 blocks), KV 8192/8192, 3090 at 23460/24576. New 'Split limits
  (measured 2026-08-17)' section: 0.50/0.54/0.55 boundary data, the
  KV-per-device rounding rule (round(f x 66)), and why 35 blocks is
  unreachable (9-FA flip at f~0.538).
- PP doc: cache incident writeup - full Dankserver disk -> 0-byte cache
  entries -> corrupt weights -> degenerate output; fix + signature.
- deployment.md + AGENTS.md + index.md: numbers brought current.
- scripts/prune-rpc-cache.sh: cron guard capping the worker cache at
  40 GiB (oldest first) to prevent the disk-full recurrence.

docs/qwen3.8-spec-matrix.md

@@ -5,32 +5,36 @@ tuning for the unsloth Qwen3.8-27B `UD-Q8_K_XL` service
 (`frank-default-large`), now a pipeline-parallel head with a Dankserver
 worker.
 
-## Production state (2026-08-16: PP split + MTP)
+## Production state (2026-08-17: single 262k slot, split 0.53)
 
 Current production, verified against the live process and journal
-(2026-08-16, service start 15:03). Topology detail:
+(2026-08-17, load 01:21, output smoke test). Topology detail:
 [[Pipeline Parallelism/Qwen3.8 PP Deployment]].
 
 - Devices: `RPC0` (Dankserver RTX 3090) + `ROCm0` (Strix iGPU). The head
   passes no `--device` flag. Default selection puts RPC first and picks
   ROCm for the iGPU (HIP registers before Vulkan). The Vulkan0 side stays
   an option via `HEAD_BIN=.../build-vulkan-rpc`.
-- Split: `--tensor-split 0.40,0.60` — 40% of the layers on the 3090
-  (its maximum under the KV budget), 60% on the iGPU.
-- Context: pool 401400, 2 slots. The journal reports
-  `n_ctx_slot = 200704`. The pi `models.json` declares 200000
-  (conservative).
-- Spec: **MTP re-enabled** — `--spec-type draft-mtp --spec-draft-n-max 4`
-  (bundled head) with the `--spec-default` ngram-mod fallback (48/64/24).
-  Journal acceptance over one production window: MTP mean len 3.00
-  (per-position 0.730/0.541/0.411/0.323, 58934 drafts); ngram-mod as the
-  rare fallback (423 drafts in the same window).
-- KV: `f16` K / `f16` V on both devices (15680 MiB ROCm0 + 9408 MiB RPC0
-  at load).
+- Split: `--tensor-split 0.53,0.47` — 34 of 65 blocks (0-33) on the
+  3090, about 52% of the layer weight. This is the maximum provably-safe
+  value (measured 2026-08-17): 0.54 jumped the KV to 9 full-attention
+  layers -> cudaMalloc OOM. The KV-per-device count rounds the fraction
+  over 66 layers, independent of the weight boundary; the 9-FA flip sits
+  at frac ~= 0.538. Boundary analysis: the PP deployment doc.
+- Context: pool 262144, 1 slot. `n_ctx_slot = 262144` exactly. The pi
+  `models.json` declares 262144 (contextWindow = maxTokens, house
+  convention).
+- Spec: **MTP** — `--spec-type draft-mtp --spec-draft-n-max 4` (bundled
+  head) with the `--spec-default` ngram-mod fallback (48/64/24). Smoke
+  acceptance 0.83 (50/60, 2026-08-17); full production-window stats in
+  the superseded section below.
+- KV: `f16` K / `f16` V. At the 262144 pool: 8192 MiB per device
+  (8 full-attention layers each; FA at blocks 3,7,...,63).
+- Worker steady state: 23460/24576 MiB used on the 3090, ~667 MiB free.
 - Batch 8192 / ubatch 256, `--direct-io`, `--fit off`,
   `--gpu-layers all`.
 
-## Result (superseded 2026-08-16: standalone --spec-default)
+## Result (superseded 2026-08-17: 2 slots x 200704, split 0.40)
 
 Superseded for topology on 2026-08-16, when the PP split became
 production. The ngram-mod preset survives as the fallback layer under