feat(#76): harvest request-scoped availability and freshness truth

Backend-only re-cut of the #76 availability work onto main, stacked on the
canonical Weekend Context API. Adds request-scoped freshness reporting so
aggregate responses cannot report fresh when a component is stale, plus
local-first driver summary resolution and cache/pacing truth.

The frontend half of #76 is deliberately excluded: it is built on the
Weekend shell that failed owner review, including the full-width Partial
banner treatment. Availability presentation is re-cut with the shell in #89.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

internal/query/context.go

@@ -40,6 +40,7 @@ type LiveEvidence struct {
 
 // ContextAvailability is structured source state for a referenced session.
 type ContextAvailability struct {
+	Source        string   `json:"source"`
 	Schedule      string   `json:"schedule"`
 	LiveTransport string   `json:"live_transport"`
 	LiveSession   string   `json:"live_session"`
@@ -298,21 +299,28 @@ func meetingModelByKey(meetings []store.Meeting, key int) *models.Meeting {
 func sessionRef(c contextCandidate, evidence LiveEvidence, now time.Time) *ContextSession {
 	session := sessionToModel(c.session)
 	meeting := meetingToModel(c.meeting)
-	availability := ContextAvailability{Schedule: "available", LiveSession: "inactive", Archive: "unavailable", Freshness: "fresh", Limitations: []string{}}
+	// Schedule and analysis are domain-store facts. Without an ingestion
+	// timestamp the resolver cannot honestly call them network-fresh, so local
+	// is the baseline freshness vocabulary exposed to clients.
+	availability := ContextAvailability{Source: "local", Schedule: "available", LiveSession: "inactive", Archive: "unavailable", Freshness: "local", Limitations: []string{}}
 	availability.LiveTransport = "unknown"
 	if c.session.SessionKey == 0 {
 		availability.Schedule = "unavailable"
 		availability.Limitations = append(availability.Limitations, "schedule_identity_unmatched")
 	}
 	if evidence.Active && liveMatches(evidence, c.meeting, c.session) {
+		availability.Source = "mixed"
 		availability.LiveTransport = "connected"
 		availability.LiveSession = "active"
+		availability.Freshness = "live"
 		if !evidence.ObservedAt.IsZero() {
 			availability.ObservedAt = evidence.ObservedAt.Format(time.RFC3339)
 		}
 	}
 	if c.archived {
+		availability.Source = "mixed"
 		availability.Archive = "available"
+		availability.Freshness = "archive"
 		if !evidence.ObservedAt.IsZero() {
 			availability.ObservedAt = evidence.ObservedAt.Format(time.RFC3339)
 		}
@@ -326,6 +334,12 @@ func sessionRef(c contextCandidate, evidence LiveEvidence, now time.Time) *Conte
 	} else {
 		availability.LocalAnalysis = "pending"
 	}
+	if availability.LocalAnalysis == "partial" && availability.Freshness == "local" {
+		availability.Freshness = "partial"
+	}
+	if c.session.SessionKey == 0 && availability.LiveSession == "active" {
+		availability.Source = "fia"
+	}
 	return &ContextSession{Session: session, Meeting: &meeting, Availability: availability}
 }
 

internal/query/context_test.go

@@ -160,6 +160,54 @@ func TestResolveWeekendContextPassedTimeDoesNotCompleteSession(t *testing.T) {
 	}
 }
 
+func TestResolveWeekendContextAvailabilityUsesTruthfulSources(t *testing.T) {
+	now, _ := time.Parse(time.RFC3339, "2026-07-05T18:00:00Z")
+	svc := contextService(t, now)
+	addContextMeeting(t, svc, 1, "British Grand Prix", "2026-07-03T00:00:00Z", "2026-07-05T16:00:00Z", false)
+	addContextSession(t, svc, 11, 1, "Race", "2026-07-05T14:00:00Z", "2026-07-05T16:00:00Z", false)
+	// Results without laps/stints/positions are meaningful but incomplete local
+	// analysis, so they must not be labelled universally fresh.
+	completeContextSession(t, svc, 11, 1)
+	addContextMeeting(t, svc, 2, "Belgian Grand Prix", "2026-07-17T00:00:00Z", "2026-07-19T16:00:00Z", false)
+	addContextSession(t, svc, 21, 2, "Practice 1", "2026-07-17T09:00:00Z", "2026-07-17T10:00:00Z", false)
+	addContextSession(t, svc, 22, 2, "Race", "2026-07-19T14:00:00Z", "2026-07-19T16:00:00Z", false)
+
+	local, err := svc.ResolveWeekendContext(LiveEvidence{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := local.PreviousCompletedSession.Availability; got.Source != "local" || got.Freshness != "partial" || got.LocalAnalysis != "partial" {
+		t.Fatalf("partial local availability = %+v", got)
+	}
+	if got := local.NextSession.Availability; got.Source != "local" || got.Freshness != "local" {
+		t.Fatalf("future local availability = %+v", got)
+	}
+
+	liveContext, err := svc.ResolveWeekendContext(LiveEvidence{Active: true, MeetingName: "Belgian Grand Prix", CircuitName: "Belgian Grand Prix", SessionName: "Practice 1", SessionType: "Practice 1", ObservedAt: now})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := liveContext.ActiveSession.Availability; got.Source != "mixed" || got.Freshness != "live" || got.LiveSession != "active" {
+		t.Fatalf("FIA + local availability = %+v", got)
+	}
+
+	archiveContext, err := svc.ResolveWeekendContext(LiveEvidence{Final: true, MeetingName: "British Grand Prix", CircuitName: "British Grand Prix", SessionName: "Race", SessionType: "Race", ObservedAt: now})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := archiveContext.PreviousCompletedSession.Availability; got.Source != "mixed" || got.Freshness != "archive" || got.Archive != "available" {
+		t.Fatalf("FIA archive + local availability = %+v", got)
+	}
+
+	synthetic, err := svc.ResolveWeekendContext(LiveEvidence{Active: true, MeetingName: "Unscheduled Grand Prix", SessionName: "Race", SessionType: "Race", ObservedAt: now})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := synthetic.ActiveSession.Availability; got.Source != "fia" || got.Freshness != "live" || got.Schedule != "unavailable" {
+		t.Fatalf("synthetic FIA availability = %+v", got)
+	}
+}
+
 func TestResolveWeekendContextNeverUsesFutureAnalysis(t *testing.T) {
 	now, _ := time.Parse(time.RFC3339, "2026-07-01T12:00:00Z")
 	svc := contextService(t, now)