REPORT — `harness serve`: OpenAI-compatible front door (OWUI is the client)

Date: 2026-08-29 ~01:30 | Repo: ukrrs/MOPAC (harness/) | Status: DONE, live on LAN port 8090, pushed to origin main (2901bb8..704f905)

What it is

harness serve = the OWUI front door from DESIGN (hermes killed; OpenWebUI = interactive surface with Cloudron SSO + admin RBAC we do not build). OWUI adds MOPAC as an OpenAI connection; each task class registers as a "model". OWUI chat and webhooks (harness events, port 4100) are now two doors into the same conductor loop. v0: stateless, non-streaming, tools off.

Endpoints (port 8090, own port — coexists with events on 4100)

Route	Auth	Behavior
`POST /v1/chat/completions`	Bearer vkey	ONE bounded stateless conductor turn over the full history OWUI sends; reply = single assistant message + usage. `temperature`/`max_tokens` forwarded. `stream:true` = explicit 400.
`GET /v1/models`	Bearer vkey	the servable catalog (below)
`GET /healthz`	none	liveness

Auth = constant-time SHA-256 digest compare of the Bearer vkey; missing / wrong / malformed keys all get one byte-identical generic 401. vkey is a config ref ([serve] vkey_ref = "env:HARNESS_SERVE_VKEY"), never logged. Unknown model = 400 naming the valid ones. Upstream failures = terse 502.

Model catalog (as configured in harness.toml right now)

Every [models.classes] class is exposed as model mopac-<class>, routed through the existing [models] tier table to the concrete proxy model:

OWUI model name	Tier	Concrete model (sent to LiteLLM)
`mopac-primary`	mopac-primary	glm-5.3 (default / flagship+)
`mopac-code`	mopac-code	glm-5.2 (flagship)
`mopac-architecture`	mopac-code	glm-5.2
`mopac-review`	mopac-review	glm-5-turbo (mid)
`mopac-summarize`	mopac-review	glm-5-turbo
`mopac-writeback`	mopac-review	glm-5-turbo
`mopac-study`	mopac-study	glm-4.7-flash (flash)
`mopac-read`	mopac-study	glm-4.7-flash
`mopac-vision`	mopac-vision	glm-4.6v

[serve] enabled_models can narrow this to a subset if you want fewer buttons in OWUI (validated at config load).

OWUI connection settings (plug these in)

Base URL: http://192.168.3.78:8090/v1
API key (vkey): mopac-owui-f2fa1879c71b8d7c83098c7838f8859d3b85d3bf (canonical copy: ~/.coordinate/secrets/mopac-serve-vkey.env, 0600 — same value as env var HARNESS_SERVE_VKEY; revoke = mint a new one + restart)
In OWUI: Admin Settings -> Connections -> add OpenAI API connection with the above, then pull the model list (the 9 mopac-* models appear); per-user/group model access is OWUI's RBAC, not ours.
OWUI must NOT request streaming for this connection (v0 returns an explicit 400 on stream:true; OWUI tolerates non-streaming providers — toggle in the connection settings if a client defaults to streaming).

How to run / restart

cd ~/projects/meta/MOPAC/harness
set -a; . ~/.coordinate/secrets/mopac-harness-vkey.env   # HARNESS_LITELLM_KEY
        . ~/.coordinate/secrets/mopac-serve-vkey.env     # HARNESS_SERVE_VKEY
set +a
./dev.sh serve          # container mopac-serve, port 8090 on the LAN
# stop: docker rm -f mopac-serve   (exact container, never pkill)

It is RUNNING now (container mopac-serve, up as of this report).

Implementation notes

Turn machinery REUSED, not copied: loop.turn refactored into a shared bounded-turn core (runTurn) that takes arbitrary message history, an optional tool palette, and forwarded max_tokens/temperature. once/loop behavior unchanged (all prior tests pass untouched); the serve path calls the same core with tools hard-off (a hallucinated tool call is refused as a tool result, never executed).
History assembly: OWUI's own leading system message is preserved verbatim (OWUI personas win); only when none is sent does the harness prepend a minimal vertical-identity prompt.
Commits (logical chunks, all Docker-built via digest-pinned builder): 8614827 loop refactor, c54a5a4 [serve] config, c9e86ee serve + CLI + dev.sh runner, 704f905 docs. Pushed to origin main.

Test results

./dev.sh check (build + vet + test, golang:1.26 builder): ALL GREEN —

ok  internal/config    ok  internal/events   ok  internal/intake
ok  internal/llm       ok  internal/loop     ok  internal/models
ok  internal/serve     ok  internal/tools    ok  internal/writeback

Serve tests: scripted fake OpenAI upstream against the REAL server — auth matrix (missing/malformed/wrong key 401, generic body, no vkey leak), catalog + enabled_models subset, end-to-end chat (concrete model on the wire, no tools, OpenAI response shape, usage), history assembly both ways, multi-round usage accounting (refused tool call fed back, sums 40/30/70), temperature/max_tokens forwarding, unknown-model 400 naming valid ones, stream 400, empty/bad-role/malformed 400s, upstream 502, fail-fast construction.
Loop tests: ServeTurn system-prompt prepend/preserve, tools-off refusal (allow-listed pwd NOT executed), knob forwarding, Router accessor.
Live LAN proof (python urllib, curl banned on host): healthz 200; wrong key 401; catalog 200 (all 9 models); unknown model 400 listing them; stream 400; REAL turns through LiteLLM — mopac-primary -> glm-5.3 ("MOPAC demo door" reply, 255 tokens, finish stop) and mopac-study -> glm-4.7-flash (166 tokens). Audit lines log routing + counters only.

Next (per TASK: streaming, tools; plus the obvious follow-ons)

Streaming: SSE stream:true path on the serve door (needs the llm client's streaming + truncation-resume work, already on the phase 3 list).
Tools in serve turns: per-vertical gated tool palette inside serve turns (the machinery already supports a palette; it is deliberately nil for v0).
Per-connection vkeys (LiteLLM-vkey-style minting via keyproxy) instead of one vkey per harness instance.
Each onstage/offstage stack gets its own harness serve instance with its own vertical name + class map — that is how "each stack registers as a model in OWUI" scales past one box.

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REPORT — harness serve: OpenAI-compatible front door (OWUI is the client)