Maven/docs/offload.md

# Offloading model work to the workstation

*Last verified: 2026-08-03 @ 12530c8. Living doc: correct it in place, do not append.*

Owner's call, 2026-08-02. Vikunja #483 is the umbrella. Tasks #484 to #487 are the
work, and this file holds the shape and the rules all four must obey.

## The goal

homesrv cannot grow a GPU. The workstation has 16GB of VRAM. Move the model work
to the workstation and leave homesrv running the logic that must be always-on,
deterministic and cheap.

## Why this is tractable

The split already exists structurally. `mavsttd` and `mavttsd` are separate
daemons that core reaches over a socket, not linked libraries. Moving them off-box
is a transport change, not a redesign.

The microphone is at the workstation, because that is where the owner sits and
homesrv is headless. So speech-to-text and the wake word are already on the
workstation side by construction. Audio never has to cross the LAN. Only the core
turn does.

## The constraint that shapes everything

The workstation's GPU is often busy: CPT runs, experiments, Correx, the manga-recap
pipeline. It also sleeps. homesrv does not.

So an offloaded model is never *the* model. It is the preferred one, with a floor
on homesrv. That is the shape the cascade already has, where a router error falls
through to the classifier.

## The degradation rule

Two cases, and the line between them is sharp.

**Fall back silently** when the workstation model would only do the job *better*:
routing, phrasing, a nudge. Falling back costs nothing that exists today, because
the resident Qwen3-1.7B is today's production quality. The owner should not be told
that his reply was phrased by the smaller model.

**Name the gap** when the resident model cannot do the job *at all*. A world
question that a 1.7B answers by inventing is the case. A wrong answer is worse
than "не могу сейчас". This is the rule CLAUDE.md already states for a sibling
service being down.

Nothing in between. A turn never breaks on the workstation being asleep.

Both halves are wired, 03-08-2026. `LLMPhraser.PhraseWorld`
(`internal/phraser/world.go`) is the naming half and has three outcomes, not two:

| State | What he hears |
|---|---|
| no `workstation` block | the resident model answers, exactly as before the seam existed |
| configured, card free | the workstation answers |
| configured, asleep or busy | the gap, `worldGap` in `cmd/mavend/worldmodel.go` |

The first row is the one worth stating. Naming a gap requires a gap. On a box with
no second model the 1.7B is the whole product. Refusing every world question there
would remove a capability the owner has today.

A source holding a passage is on the naming half too: a live search, a ZIM
article, a page he named. None of them says "не могу сейчас". They read the
passage back, which is what `phraseSource` returning `""` selects. A real quote
beats a gap, and neither path invents.

## Admission control, not a scheduler

There is no GPU arbiter. That is a service with its own failure modes, and nothing
here needs work *distributed*. It needs admission control. The workstation
advertises free VRAM over a health endpoint, and Maven treats it as one more query
source that claims a turn or passes. llama-server also refuses to load when VRAM is
short, so the failure is detectable without cooperation from the owner's other
jobs.

The caller must be able to ask "is this peer usable right now" without a turn
hanging on a timeout. A dead remote is a normal state, not an error state.
`internal/llm.Pair` is that check on the Maven side. A prober caches the answer,
so `Available()` is an atomic read and no turn pays for a health check.

llama-server does not stay up on the workstation. It cannot: a resident 7-14B
would hold 16GB against the owner's CPT runs. So a supervisor there owns its
lifecycle, keeps it loaded while the card is free, and unloads it on idle or
when another process needs the card (owner's call, 2026-08-02, Vikunja #488).

That supervisor is still not a scheduler, and the distinction is worth holding.
It arbitrates nothing between callers. It reports whether it can take work and
manages one process to back that answer. Maven never asks it to start anything
and never learns that it did.

Contention is decided by presence under `/sys/class/kfd/kfd/proc`, not by a VRAM
threshold. A ROCm process registers there when it initialises HIP, before it
allocates anything. So the supervisor sees a contender during that job's startup,
and yields before the job loses the memory it asked for. A
threshold reads the card too late. By the time free VRAM has dropped, the other
job has already lost the allocation race. Free VRAM is still read, but only as a
precondition for loading, never as the eviction signal. One blind spot is known.
A job can take the card without registering on the KFD, as a Vulkan or a
video-decode job would. `describe()` logs every contender's comm, and that log is
how we find out whether the blind spot is real.

`mavgpud` runs from a systemd unit on the workstation with
`deploy/mavgpud.json` as its config, and `llama_args` is passed to llama-server
untouched. The model, the context size, the layer count and the MTP flags are the
owner's business and not this daemon's schema.

## What stays on homesrv, permanently

The **embedder** (multilingual-e5-small, ONNX, CPU). It backs the classifier, which
must answer while the GPU is saturated. It is also cheap enough on CPU that moving
it buys nothing. Four callers:

| Caller | What for |
|---|---|
| `internal/router/classifier.go` | the routing floor |
| `cmd/mavend/actions_query.go` (`queryEmbed`) | memory recall |
| `cmd/mavend/feeds.go` | ingest embedding for every RSS item |
| `internal/crawl/watch.go` | ingest embedding for every crawled page |

`internal/speaker` becomes a fifth once it lands.

## Inventory: what runs a model on homesrv today

The **resident model** is one llama-server with seven callers, and 03-08-2026 is
the date each of them stopped or did not stop being resident-only:

| Caller | What for | Offloaded |
|---|---|---|
| `cmd/mavend/voicewire.go` | routing | silently, through `hot` |
| `cmd/mavend/replier_llm.go` | replies | silently, through `hot` |
| `cmd/mavend/tick.go` | digestion worker: `PhraseNudge`, `PhraseReminder` | silently, inside the phraser |
| `cmd/mavend/actions_query.go` | world questions, and any fetched passage | names the gap |
| `cmd/mavend/capture.go` | capture summarisation (unreachable, see #480) | no, holds its own client |
| `cmd/mavend/mail.go` | mail extraction (off, no IMAP) | no, holds its own client |
| `memoryeval.go`, `modelswap.go` | admin and evals | no, and deliberately |

The last three rows are resident-only on purpose. `memoryeval.go` and
`modelswap.go` measure and swap the resident model, so sending their work
elsewhere would measure the wrong thing. `capture.go` and `mail.go` are
background jobs that hold a gated background client (`llmBackgroundClientFor`),
and that priority has no equivalent on the remote yet. Both are also unreachable
on this deploy, so wiring them would ship an untestable path.

The `tick.go` row needs one caveat. `phraser.llm_nudges` is `false` in deploy, so
nudges come from templates and the seam under them changes nothing until that
flips. It is wired anyway: `PhraseReminder` is on the same transport and is on.

Then the embedder above, **whisper.cpp** in `mavsttd`, and **piper** in `mavttsd`.
`mavwaked` uses no model at all: an energy-threshold VAD over 30ms frames.

## Order

1. **Transport** (#484). Nothing else is possible until a seam can cross a host.
   `internal/netaddr` landed in PR #92. A seam address now carries its own scheme,
   and a scheme-less one is still unix. A tcp seam requires a shared token, because
   the filesystem permission that authenticated the unix socket is gone.
2. **The resident model** (#485, #490). Wired. A `workstation` block builds an
   `llm.Pair` in `modelSeam` (`cmd/mavend/voicewire.go`), routing and replies
   complete through it, and the phraser holds the same pair (`UseRemote`). Both
   halves of the rule are live: see the table above for which caller gets which.
   Measured, `docs/evals/2026-08-02-workstation-gemma4-12b.md`: gemma-4-12b
   through the cascade scores 84.4% full accuracy at p50 329ms. The resident
   model scores 72.7% at p50 0.80-1.04s. On the talk fixture it is 25/27
   against 20/27. Biggest quality delta. A 16GB card runs a 7-14B,
   which fixes what the 1.7B gets wrong: world knowledge, and the persona the CPT
   targets. The degradation path is already written and measured, since the
   classifier scores 68.8% full accuracy at p50 16.6µs on its own.
3. **Speech-to-text and text-to-speech** (#486). They gain a real margin, but on
   quality alone, and both already work.
4. **The wake word** (#487). Independent of all of the above.

## Assumptions

- The LAN is trusted enough that wireguard is supported but not required (owner's
  call). What crosses the wire is still his utterances. That is why the tcp seam
  carries its own token instead of assuming a network boundary.
- The workstation is not expected to be up. Every child task must still serve a
  turn while it is down.