fix(frank-large): load the model as its native 3-way split, not a concatenated file

The first cutover crash-looped the unit with 'invalid split file name':
the fetch script concatenated the three split parts into a single GGUF,
but part 1's header carries ggml.file_count=3, so the byte-correct
concatenation still advertises itself as a split and the loader demands
a -NNNNN-of-NNNNN filename.

- serve-frank-large.sh: -m points at part 1; llama.cpp loads the split
  natively (parts 2-3 auto-discovered in the same directory)
- deploy-remote.sh: LLM_LARGE_MODEL gate path follows
- download-frank-large-unsloth.sh: assembly removed; the parts ARE the
  canonical payload, verified against live Hub LFS oids
- docs: runbook model section + troubleshooting note, AGENTS.md, log
- the redundant 87 GiB assembled file is staged on dankclaw at
  ~/.AGENTTRASH/20260921-frank-large-assembled/

scripts/download-frank-large-unsloth.sh

@@ -1,29 +1,30 @@
 #!/usr/bin/env bash
-# Download and assemble unsloth/Qwen3.8-Flash-Next-GGUF:UD-IQ4_XS (the
+# Download unsloth/Qwen3.8-Flash-Next-GGUF:UD-IQ4_XS (the
 # frank-large model) on Dankclaw.
 #
 #   bash scripts/download-frank-large-unsloth.sh
 #   bash scripts/download-frank-large-unsloth.sh --verify-only
 #
 # The UD-IQ4_XS GGUF ships as three llama.cpp split parts (HF caps uploads at
-# 50 GB); concatenating them in numeric order reconstructs the single GGUF.
+# 50 GB). The parts ARE the canonical payload: the serve script points -m at
+# part 1 and llama.cpp loads the 3-way split natively. Do NOT concatenate
+# them into a single file to serve — part 1's header carries
+# ggml.file_count=3, so a byte-correct concatenation still advertises itself
+# as a split and the loader rejects the non-split filename.
 # The MTP shared-Q8_0 head borrows the token embedding and the output
 # projection from the main model at runtime (it is the 2.6 GB remainder of
 # the 4B MTP layer). The F16 projector is fetched for a future vision flip;
 # the serve script does not load it while ENABLE_VISION=0.
 #
 # Integrity: every part is checked against its LFS sha256 (fetched live from
-# the Hub tree API, not trusted from disk), then the assembled GGUF against
-# the recorded SHA256SUMS. The repo is public (gated: false); an HF token at
-# ~/.cache/huggingface/token is used when present to clear the anonymous rate
-# limit on a 94 GB transfer.
+# the Hub tree API, not trusted from disk). The repo is public (gated:
+# false); an HF token at ~/.cache/huggingface/token is used when present to
+# clear the anonymous rate limit on a 94 GB transfer.
 #
 # Layout after a successful run (MODEL_DIR):
-#   Qwen3.8-Flash-Next-UD-IQ4_XS.gguf             93,682,584,224  main model
+#   UD-IQ4_XS/Qwen3.8-Flash-Next-UD-IQ4_XS-0000{1,2,3}-of-00003.gguf  the 3-way split
 #   mtp/mtp-Qwen3.8-Flash-Next-shared-Q8_0.gguf   2,786,568,256  draft head
 #   vision/mmproj-F16.gguf                         904,004,000  projector
-#   UD-IQ4_XS/  the three verified transport parts (kept for --verify-only)
-#   SHA256SUMS
 set -euo pipefail
 
 REPO="unsloth/Qwen3.8-Flash-Next-GGUF"
@@ -104,19 +105,11 @@ for rel in sorted(expected):
 sys.exit(0 if ok else 1)
 PY
 
-FINAL="$MODEL_DIR/Qwen3.8-Flash-Next-UD-IQ4_XS.gguf"
 if [[ "$mode" == "download" ]]; then
-    echo "assembling the GGUF from the split parts"
-    cat "$MODEL_DIR"/UD-IQ4_XS/Qwen3.8-Flash-Next-UD-IQ4_XS-0000{1,2,3}-of-00003.gguf > "$FINAL"
-    [[ "$(stat -c %s "$FINAL")" -eq 93682584224 ]] || {
-        echo "assembled size wrong: $(stat -c %s "$FINAL")" >&2; exit 1; }
     mkdir -p "$MODEL_DIR/mtp" "$MODEL_DIR/vision"
     [[ -e "$MODEL_DIR/mtp/mtp-Qwen3.8-Flash-Next-shared-Q8_0.gguf" ]] ||
         mv "$MODEL_DIR/MTP/mtp-Qwen3.8-Flash-Next-shared-Q8_0.gguf" "$MODEL_DIR/mtp/"
     [[ -e "$MODEL_DIR/vision/mmproj-F16.gguf" ]] || mv "$MODEL_DIR/mmproj-F16.gguf" "$MODEL_DIR/vision/"
-    (cd "$MODEL_DIR" && sha256sum Qwen3.8-Flash-Next-UD-IQ4_XS.gguf > SHA256SUMS)
 fi
 
-echo "verifying assembled files against SHA256SUMS"
-(cd "$MODEL_DIR" && sha256sum -c SHA256SUMS)
 echo "frank-large payload complete: $MODEL_DIR"