# Qwen3.6-27B recommended deployment

## Goal

Offer the pinned `Qwen/Qwen3.6-27B` BF16 artifact as a recommended,
text-only chat model. A valid chat request proves model demand. When the
shared tracker pool has sufficient eligible capacity, the tracker deploys the
model rather than waiting for an operator to request a load.

## Catalog and artifacts

- Canonical artifact: `Qwen/Qwen3.6-27B` at
  `6a9e13bd6fc8f0983b9b99948120bc37f49c13e9`.
- Tracker/peer artifact sources remain preferred over Hugging Face; this is a
  system rule, not model-specific behavior.
- BF16 is canonical. Nodes may load BF16, INT8, or NF4 from the canonical
  shard according to their declared capability.
- The model is text-only for this feature. Image inputs are rejected rather
  than implicitly advertised as supported.

## Quantization contract

- Chat accepts an optional `quantization` field: `bfloat16`, `int8`, or
  `nf4`. Omission means `bfloat16`.
- A request is a minimum-quality constraint: BF16 uses BF16 only; INT8 can
  use INT8 or BF16; NF4 can use NF4, INT8, or BF16.
- A selectable variant requires complete end-to-end coverage using only
  qualifying shards. Mixed qualifying precision is valid.
- The UI defaults to the highest complete coverage, lists unavailable variants
  as non-selectable, and gives them a small coverage-vote control.

## Demand and placement

- The first valid model request queues initial tracker-managed placement when
  sufficient pooled capability exists. Until complete coverage exists, return
  retryable `503 model_loading` with coverage metadata.
- Demand and node supply are hive-wide; a leader makes each assignment and
  broadcasts it to redundant trackers.
- A request for an unavailable quantization is retained as demand. Votes are
  weaker when another Qwen quantization is already usable.
- If deployment replaces existing complete coverage, rolling demand for the
  requested variant must exceed the displaced variant by more than 1.5x.
  The multiplier and rolling window are tracker configuration.
- Managed replacements require at least three complete copies beforehand and
  must leave two. Managed placement has a configurable cooldown.

## Node ownership

- A startup-assigned `(model, shard range, quantization)` is pinned and never
  changed by the tracker.
- Spare capacity on a pinned node, and all capacity on a model-less node, is
  available for tracker-managed assignments.
- Tracker-added assignments are explicitly marked managed and may be moved or
  removed by the tracker under the safety policy. Runtime UI controls are a
  later feature.

## Pricing

Use exact-model online provider pricing. Preserve the last verified price if
the provider lookup fails; use a model-specific development fallback only when
there is no verified price.