config: a workstation block, dropped when it names no address (V-485)

Health defaults to the supervisor's /health rather than llama-server's,
because mavgpud is what answers 503 while the card is held.

internal/config/config.go

@@ -224,6 +224,11 @@ type Config struct {
 	// See SearchConfig.
 	Search *SearchConfig `json:"search,omitempty"`
 
+	// Workstation — the big model on the owner's desktop, preferred over the
+	// resident one when its GPU is free. nil / absent / url empty ⇒ homesrv
+	// behaves exactly as it does today. See WorkstationConfig.
+	Workstation *WorkstationConfig `json:"workstation,omitempty"`
+
 	// Praxis — the ecosystem attention-state service. When configured, maven
 	// calls the Praxis HTTP tools API for attention listing and item lifecycle.
 	// Maven never touches Praxis's database directly (ecosystem invariant: no
@@ -1105,6 +1110,44 @@ const (
 	DefaultKiwixSnippetRunes = 1500
 )
 
+// WorkstationConfig — the big model on the owner's desktop (bugmachine, a
+// 7900 GRE with 16GB), fronted by mavgpud.
+//
+// homesrv cannot grow a GPU, so the resident Qwen3-1.7B is the floor and this
+// is the preferred model above it (owner's call, 2026-08-02, docs/offload.md).
+// The workstation is never assumed up: its card is often held by a CPT run and
+// the machine sleeps. No block, or an empty URL, and homesrv behaves exactly as
+// it does today.
+//
+// Only the prompt crosses the LAN, and the workstation is not "the box". The
+// rules in CLAUDE.md about what may leave still apply.
+type WorkstationConfig struct {
+	// URL — where mavgpud listens, e.g. "http://192.168.1.105:8080". Empty ⇒
+	// the whole block is normalised to nil and nothing probes anything.
+	URL string `json:"url,omitempty"`
+
+	// Health — the admission endpoint. Empty ⇒ URL + "/health", which is what
+	// mavgpud serves. It answers 503 while the card is held, and that is the
+	// signal, so it must be the supervisor's endpoint and not llama-server's.
+	Health string `json:"health,omitempty"`
+
+	// Probe — how often admission is re-checked. 0 ⇒ DefaultWorkstationProbe.
+	// Nothing on the hot path waits for it: the answer is cached and read
+	// atomically, so this only sets how late Maven notices the card came back.
+	Probe Duration `json:"probe,omitempty"`
+
+	// Timeout — the per-request budget for a completion on the workstation.
+	// 0 ⇒ DefaultWorkstationTimeout. A big model on a LAN host is slower than
+	// the resident one, and a request that overruns falls back to the floor.
+	Timeout Duration `json:"timeout,omitempty"`
+}
+
+// Workstation defaults, applied in Normalise.
+const (
+	DefaultWorkstationProbe   = 15 * time.Second
+	DefaultWorkstationTimeout = 90 * time.Second
+)
+
 // SearchConfig — the self-hosted SearXNG instance she searches with.
 //
 // External search is allowed and off unless configured (CLAUDE.md). Configuring
@@ -1500,6 +1543,24 @@ func (c *Config) applyDefaults() {
 		}
 	}
 
+	// No address, no preferred model. An unconfigured workstation is the
+	// default deploy and must be indistinguishable from today.
+	if c.Workstation != nil && strings.TrimSpace(c.Workstation.URL) == "" {
+		c.Workstation = nil
+	}
+	if c.Workstation != nil {
+		w := c.Workstation
+		if strings.TrimSpace(w.Health) == "" {
+			w.Health = strings.TrimRight(w.URL, "/") + "/health"
+		}
+		if w.Probe <= 0 {
+			w.Probe = Duration(DefaultWorkstationProbe)
+		}
+		if w.Timeout <= 0 {
+			w.Timeout = Duration(DefaultWorkstationTimeout)
+		}
+	}
+
 	if c.Voice != nil {
 		if c.Voice.RouterThreshold <= 0 {
 			c.Voice.RouterThreshold = DefaultRouterThreshold