feat(grafana): graph frank-archon in llm-fleet (radiance vllm:*/radiance:* + a new endpoint section)

frank-archon (radiance, Dankserver) emits vllm:* + radiance:* (job=frank-archon).
llm-fleet.json queried only llamacpp:* and its endpoint picker selected via
label_values(llamacpp:.*), so archon - despite being scraped and alert-on
(vllm-fleet group) - had zero panels. The dashboard description also still
claimed archon was llama.cpp, which is stale.

- Fix the description: two namespaces; the $job picker is the llama.cpp pair
  (dragoon/zealot); archon is radiance and gets its own section.
- Add a frank-archon row + 8 panels: vllm:* throughput, request outcomes by
  finish reason, queue/preemption, TTFT p50/p95, and the radiance natives vllm
  omits - decode/prefill t/s, MTP draft acceptance, engine-step timing, prefix
  hit. All 14 queries verified live against Prometheus (non-empty).

Dashboards-only; the next grafana deploy provisions it.

shared/grafana/provisioning/dashboards/llm-fleet.json

@@ -1,7 +1,7 @@
 {
   "uid": "llm-fleet",
   "title": "LLM fleet \u2014 capacity and reuse",
-  "description": "The signals that explain the LLM endpoints under load. One metric namespace: llamacpp:* across all three endpoints — frank-zealot (Dankclaw, RTX 3090), frank-dragoon (Dankclaw, gfx1151 iGPU) and frank-archon (Dankserver, 2x R9700, llama.cpp again since the 2026-09-26 swap back from Lucebox DS4.1). The endpoint picker selects between them. See serverAppConfigs-docs/Infrastructure/Observability.md for the namespace split and the addressability rules.",
+  "description": "The signals that explain the LLM endpoints under load, in TWO namespaces. Panels 1-6 are llama.cpp (llamacpp:*) and the endpoint picker ($job) selects frank-zealot (Dankclaw, RTX 3090) and frank-dragoon (Dankclaw, gfx1151 iGPU). frank-archon (Dankserver, 2x R9700) is radiance, NOT llama.cpp: it emits vllm:* and radiance:* (job=frank-archon) and has its own section at the bottom - those families are alert-on but were never graphed here until now. See serverAppConfigs-docs/Infrastructure/Observability.md.",
   "tags": [
     "llm",
     "capacity"
@@ -212,6 +212,98 @@
           "refId": "A"
         }
       ]
+    },
+    {
+      "id": 100,
+      "type": "row",
+      "title": "frank-archon \u2014 radiance (vllm:* + radiance:*)",
+      "collapsed": false,
+      "gridPos": { "h": 1, "w": 24, "x": 0, "y": 33 },
+      "panels": []
+    },
+    {
+      "id": 101, "type": "timeseries", "title": "Archon throughput (tokens/s)",
+      "description": "vLLM-compat counters: prompt and generation token rates for frank-archon.",
+      "gridPos": { "h": 8, "w": 12, "x": 0, "y": 34 },
+      "datasource": { "type": "prometheus", "uid": "prometheus" },
+      "fieldConfig": { "defaults": { "unit": "short", "min": 0, "custom": { "fillOpacity": 10, "lineWidth": 1 } }, "overrides": [] },
+      "targets": [
+        { "expr": "sum(rate(vllm:prompt_tokens_total{job=\"frank-archon\"}[5m]))", "legendFormat": "prompt/s", "refId": "A" },
+        { "expr": "sum(rate(vllm:generation_tokens_total{job=\"frank-archon\"}[5m]))", "legendFormat": "generation/s", "refId": "B" }
+      ]
+    },
+    {
+      "id": 102, "type": "timeseries", "title": "Archon request outcomes",
+      "description": "Completed requests/s by finish reason (stop / length / tool_calls / abort).",
+      "gridPos": { "h": 8, "w": 12, "x": 12, "y": 34 },
+      "datasource": { "type": "prometheus", "uid": "prometheus" },
+      "targets": [
+        { "expr": "sum by (finished_reason)(rate(vllm:request_success_total{job=\"frank-archon\"}[5m]))", "legendFormat": "{{finished_reason}}", "refId": "A" }
+      ]
+    },
+    {
+      "id": 103, "type": "timeseries", "title": "Archon queue and preemptions",
+      "description": "num_requests_waiting is the queue gauge (VllmRequestsQueueing fires on >0); preemption rate (VllmPreempting).",
+      "gridPos": { "h": 8, "w": 12, "x": 0, "y": 42 },
+      "datasource": { "type": "prometheus", "uid": "prometheus" },
+      "targets": [
+        { "expr": "vllm:num_requests_waiting{job=\"frank-archon\"}", "legendFormat": "waiting", "refId": "A" },
+        { "expr": "sum(rate(vllm:num_preemptions_total{job=\"frank-archon\"}[5m]))", "legendFormat": "preemptions/s", "refId": "B" }
+      ]
+    },
+    {
+      "id": 104, "type": "timeseries", "title": "Archon time-to-first-token",
+      "description": "TTFT p50/p95 from the vLLM histogram. VllmTtftSlow alerts when the p95 recording rule exceeds 120 s.",
+      "gridPos": { "h": 8, "w": 12, "x": 12, "y": 42 },
+      "datasource": { "type": "prometheus", "uid": "prometheus" },
+      "fieldConfig": { "defaults": { "unit": "s", "min": 0, "custom": { "fillOpacity": 10, "lineWidth": 1 } }, "overrides": [] },
+      "targets": [
+        { "expr": "histogram_quantile(0.5, sum by (le)(rate(vllm:time_to_first_token_seconds_bucket{job=\"frank-archon\"}[5m])))", "legendFormat": "p50", "refId": "A" },
+        { "expr": "histogram_quantile(0.95, sum by (le)(rate(vllm:time_to_first_token_seconds_bucket{job=\"frank-archon\"}[5m])))", "legendFormat": "p95", "refId": "B" }
+      ]
+    },
+    {
+      "id": 105, "type": "timeseries", "title": "Archon radiance decode/prefill t/s",
+      "description": "radiance-native instantaneous throughput gauges - the engine's own view, not the vLLM counter derivative.",
+      "gridPos": { "h": 8, "w": 12, "x": 0, "y": 50 },
+      "datasource": { "type": "prometheus", "uid": "prometheus" },
+      "targets": [
+        { "expr": "radiance:decode_tokens_per_second{job=\"frank-archon\"}", "legendFormat": "decode t/s", "refId": "A" },
+        { "expr": "radiance:prefill_tokens_per_second{job=\"frank-archon\"}", "legendFormat": "prefill t/s", "refId": "B" }
+      ]
+    },
+    {
+      "id": 106, "type": "timeseries", "title": "Archon speculative decode (MTP)",
+      "description": "radiance draft acceptance - the native signal vLLM metrics omit. The whole reason radiance exposes its own endpoint.",
+      "gridPos": { "h": 8, "w": 12, "x": 12, "y": 50 },
+      "datasource": { "type": "prometheus", "uid": "prometheus" },
+      "fieldConfig": { "defaults": { "unit": "percentunit", "min": 0, "max": 1, "custom": { "fillOpacity": 10, "lineWidth": 1 } }, "overrides": [] },
+      "targets": [
+        { "expr": "radiance:draft_acceptance_ratio{job=\"frank-archon\"}", "legendFormat": "acceptance ratio", "refId": "A" },
+        { "expr": "sum(rate(radiance:draft_accepted_total{job=\"frank-archon\"}[5m])) / clamp_min(sum(rate(radiance:draft_tokens_total{job=\"frank-archon\"}[5m])), 0.001)", "legendFormat": "accepted/token", "refId": "B" }
+      ]
+    },
+    {
+      "id": 107, "type": "timeseries", "title": "Archon engine step time",
+      "description": "radiance engine-step accounting: mean decode step duration (seconds per step) plus prefill steps/s.",
+      "gridPos": { "h": 8, "w": 12, "x": 0, "y": 58 },
+      "datasource": { "type": "prometheus", "uid": "prometheus" },
+      "fieldConfig": { "defaults": { "unit": "s", "min": 0, "custom": { "fillOpacity": 10, "lineWidth": 1 } }, "overrides": [] },
+      "targets": [
+        { "expr": "rate(radiance:engine_step_seconds_decode_total{job=\"frank-archon\"}[5m]) / clamp_min(rate(radiance:engine_steps_decode_total{job=\"frank-archon\"}[5m]), 0.001)", "legendFormat": "avg decode step", "refId": "A" },
+        { "expr": "sum(rate(radiance:engine_steps_prefill_total{job=\"frank-archon\"}[5m]))", "legendFormat": "prefill steps/s", "refId": "B" }
+      ]
+    },
+    {
+      "id": 108, "type": "timeseries", "title": "Archon prefix cache hit rate",
+      "description": "vLLM and radiance prefix-cache hit rates. A collapse fires VllmPrefixCacheCollapse.",
+      "gridPos": { "h": 8, "w": 12, "x": 12, "y": 58 },
+      "datasource": { "type": "prometheus", "uid": "prometheus" },
+      "fieldConfig": { "defaults": { "unit": "percentunit", "min": 0, "max": 1, "custom": { "fillOpacity": 10, "lineWidth": 1 } }, "overrides": [] },
+      "targets": [
+        { "expr": "vllm:gpu_prefix_cache_hit_rate{job=\"frank-archon\"}", "legendFormat": "vllm prefix hit", "refId": "A" },
+        { "expr": "radiance:linear_prefix_cache_hit_rate{job=\"frank-archon\"}", "legendFormat": "radiance prefix hit", "refId": "B" }
+      ]
     }
   ]
 }