feat(metrics): add persistent LLM usage analytics

server/commands.go

@@ -4,6 +4,8 @@ import (
 	"net/http"
 	"strconv"
 	"strings"
+
+	"github.com/Autumn-27/artex/db"
 )
 
 // pgListCommands returns tool executions (any tool) from the activity table.
@@ -45,6 +47,53 @@ func (s *Server) pgListLLMRecords(w http.ResponseWriter, r *http.Request) {
 	writeJSON(w, 200, map[string]any{"records": records, "total": total})
 }
 
+// pgTokenByModel returns a task's LLM token usage grouped by model, from the
+// always-on llm_usage metering ledger. Accurate even with per-agent model bindings,
+// pool rotation/failover, and interrupted runs (every call is metered on success or
+// error). No recording toggle required.
+func (s *Server) pgTokenByModel(w http.ResponseWriter, r *http.Request) {
+	id := strings.TrimSpace(r.URL.Query().Get("task"))
+	if id == "" {
+		writeErr(w, 400, "missing task")
+		return
+	}
+	pg := s.m.PG()
+	if pg == nil {
+		writeJSON(w, 200, map[string]any{"models": []db.ModelTokenStat{}})
+		return
+	}
+	models, err := pg.TokenByModel(id)
+	if err != nil {
+		writeErr(w, 500, err.Error())
+		return
+	}
+	writeJSON(w, 200, map[string]any{"models": models})
+}
+
+// pgUsageStats returns global llm_usage aggregates for the dashboard's "new" token
+// view: per-profile totals (all-time) + per-(profile, day) buckets for the daily
+// chart. Sourced from the always-on metering ledger, so it is accurate across
+// per-agent bindings, pool rotation, and interrupted runs.
+func (s *Server) pgUsageStats(w http.ResponseWriter, r *http.Request) {
+	pg := s.m.PG()
+	if pg == nil {
+		writeJSON(w, 200, map[string]any{"by_profile": []db.ProfileUsage{}, "daily": []db.ProfileDayUsage{}})
+		return
+	}
+	days := atoiDefault(r.URL.Query().Get("days"), 365)
+	byProfile, err := pg.UsageByProfile()
+	if err != nil {
+		writeErr(w, 500, err.Error())
+		return
+	}
+	daily, err := pg.UsageDaily(days)
+	if err != nil {
+		writeErr(w, 500, err.Error())
+		return
+	}
+	writeJSON(w, 200, map[string]any{"by_profile": byProfile, "daily": daily})
+}
+
 // pgLLMTasks returns distinct recorded tasks with counts, for the page's task
 // picker (pick a task → filter the list, then delete its conversations).
 func (s *Server) pgLLMTasks(w http.ResponseWriter, r *http.Request) {