internal/server,shared: support request metadata (#850)

- add support for http handlers in the request chain to append metadata
to the request
- metrics middleware will include metadata in the activity log 
- update Activity UI to support metadata, drag sort columns
- update Activity UI capture dialog to use more screen space

Updates #834

internal/router/scheduler/fifo.go

@@ -3,6 +3,7 @@ package scheduler
 import (
 	"fmt"
 	"sort"
+	"strconv"
 	"time"
 
 	"github.com/mostlygeek/llama-swap/internal/config"
@@ -278,6 +279,11 @@ func (s *FIFO) grantHandler(req HandlerReq, modelID string) {
 		s.effects.GrantError(req, shared.ConcurrencyLimitError{})
 		return
 	}
+
+	if err := shared.SetReqData(req.Ctx, "fifo_priority", strconv.Itoa(s.cfg.Priority[req.Model])); err != nil {
+		s.logger.Debugf("failed to set fifo_priority metadata: %v", err)
+	}
+
 	if s.effects.GrantServe(req, modelID) {
 		s.inFlight[modelID]++
 	}

internal/router/scheduler/fifo_test.go

@@ -1,6 +1,7 @@
 package scheduler
 
 import (
+	"context"
 	"errors"
 	"io"
 	"net/http"
@@ -54,8 +55,9 @@ type stopRec struct {
 // fakeEffects is an in-memory scheduler.Effects. Tests program process states
 // and GrantServe outcomes, then assert on the recorded calls.
 type fakeEffects struct {
-	states      map[string]process.ProcessState // model -> state; missing => not handled
-	serveResult map[string]bool                 // GrantServe return per model (default true)
+	states       map[string]process.ProcessState // model -> state; missing => not handled
+	serveResult  map[string]bool                 // GrantServe return per model (default true)
+	lastServeReq HandlerReq
 
 	starts []startRec
 	grants []grantRec
@@ -98,6 +100,7 @@ func (f *fakeEffects) GrantServe(req HandlerReq, modelID string) bool {
 	if v, set := f.serveResult[modelID]; set {
 		ok = v
 	}
+	f.lastServeReq = req
 	f.grants = append(f.grants, grantRec{model: modelID, serve: ok})
 	return ok
 }
@@ -169,6 +172,27 @@ func TestFIFO_FastPath(t *testing.T) {
 	}
 }
 
+func TestFIFO_GrantSetsPriorityMetadata(t *testing.T) {
+	eff := newFakeEffects()
+	eff.states["a"] = process.StateReady
+	cfg := config.FifoConfig{Priority: map[string]int{"a": 7}}
+	s := NewFIFO("test", logmon.NewWriter(io.Discard), &stubPlanner{}, cfg, nil, eff)
+
+	ctx := shared.SetContext(context.Background(), shared.ReqContextData{ModelID: "a", Metadata: make(map[string]string)})
+	s.OnRequest(HandlerReq{Model: "a", Ctx: ctx})
+
+	if got := eff.served("a"); got != 1 {
+		t.Fatalf("served(a)=%d want 1", got)
+	}
+	data, ok := shared.ReadContext(eff.lastServeReq.Ctx)
+	if !ok {
+		t.Fatal("context data missing from granted request")
+	}
+	if data.Metadata["fifo_priority"] != "7" {
+		t.Errorf("fifo_priority = %q, want 7", data.Metadata["fifo_priority"])
+	}
+}
+
 func TestFIFO_ModelNotFound(t *testing.T) {
 	eff := newFakeEffects() // no states => model unknown
 	s := newFIFO(&stubPlanner{}, eff)