Local AI: the model service production runs, and how to build its model

packaging/local-ai/ holds what runs the AI spam classifier's model on
production's mail host, for the installer's bare-metal mode to use later
(nothing in the installer uses it yet):

- inbuxa-llm.service: llama.cpp's server with Qwen3 4B Instruct 2507
  (Q4_K_M), in the mail network namespace on 127.0.0.1:8080 only, bounded
  to 4 cores and 8 GB. Identical to host1's unit apart from the license
  header.
- build-model.sh: builds the model from Qwen's official weights, checked
  against Hugging Face's checksums, with llama.cpp b11160's converter and
  quantizer, and compares the result with production's SHA-256. Qwen
  publishes no GGUF of this model, so the file that runs is one we made.
  Two builds from the same weights came out byte-identical.
- README.md: what runs and where it came from, a by-hand install, and how
  to undo it.

packaging/local-ai/inbuxa-llm.service

@@ -0,0 +1,46 @@
+# SPDX-FileCopyrightText: 2026 Coffey Labs
+# SPDX-License-Identifier: AGPL-3.0-or-later
+#
+# The local language model for inbuxa's AI spam classifier: llama.cpp's
+# server with Qwen3 4B Instruct 2507 (Apache-2.0), converted from Qwen's
+# official weights and quantized to Q4_K_M. It runs in the mail network
+# namespace and listens only on its loopback, 127.0.0.1:8080, where the mail
+# server's x:AiModel "local" points. Nothing leaves the machine.
+#
+# Bounded so it can never starve the mail server: 4 cores, 8 GB. Four slots
+# match the classifier's default of four requests in flight (inbuxa:AiLimits
+# maxConcurrentCalls), each with a 4096-token context.
+[Unit]
+Description=inbuxa local AI model (llama.cpp, Qwen3 4B Instruct 2507)
+After=mail-netns.service
+Requires=mail-netns.service
+
+[Service]
+NetworkNamespacePath=/run/netns/mail
+Environment=LD_LIBRARY_PATH=/opt/llama/b11160/llama-b11160
+ExecStart=/opt/llama/b11160/llama-b11160/llama-server \
+    --model /opt/llama/models/qwen3-4b-instruct-2507-Q4_K_M.gguf \
+    --alias qwen3-4b-instruct-2507 \
+    --host 127.0.0.1 --port 8080 \
+    --threads 4 --parallel 4 --ctx-size 16384 \
+    --no-webui
+DynamicUser=yes
+CPUQuota=400%
+MemoryMax=8G
+Nice=10
+Restart=on-failure
+RestartSec=10
+ProtectSystem=strict
+ProtectHome=yes
+PrivateTmp=yes
+NoNewPrivileges=yes
+ProtectKernelTunables=yes
+ProtectKernelModules=yes
+ProtectControlGroups=yes
+RestrictSUIDSGID=yes
+LockPersonality=yes
+CapabilityBoundingSet=
+SystemCallArchitectures=native
+
+[Install]
+WantedBy=multi-user.target