fix(sessions): reconstruct Copilot transcripts from GenAI spans

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Fixed
+
+- Fixed GitHub Copilot local session transcripts returning "Failed to load session transcript". Copilot lists sessions from `copilot_chat.session.start` logs, but conversation content is on GenAI spans; transcripts now reconstruct user, assistant, and tool messages from those spans instead of 404ing when no log events map to roles.
+
 ## [0.5.0] - 2026-06-18
 
 ### Added

backend/internal/handlers/query_test.go

@@ -643,3 +643,62 @@ func TestGetBreakdownValues(t *testing.T) {
 		})
 	}
 }
+
+func TestGetSessionTranscript_CopilotListedSessionReturnsTranscript(t *testing.T) {
+	h, cleanup := setupTestHandlers(t)
+	defer cleanup()
+
+	ctx := context.Background()
+	now := time.Now().UTC().Truncate(time.Millisecond)
+	sessionID := "copilot-conv-1"
+
+	if err := h.store.InsertLogs(ctx, []api.LogRecord{{
+		Timestamp:   now,
+		ServiceName: "copilot-chat",
+		Body:        "copilot_chat.session.start",
+		LogAttributes: map[string]string{
+			"event.name": "copilot_chat.session.start",
+			"session.id": sessionID,
+		},
+	}}); err != nil {
+		t.Fatalf("failed to insert copilot session log: %v", err)
+	}
+	if err := h.store.InsertSpans(ctx, []api.Span{{
+		Timestamp:   now.Add(time.Second),
+		TraceID:     "trace-copilot",
+		SpanID:      "span-agent",
+		ServiceName: "copilot-chat",
+		SpanName:    "invoke_agent copilot",
+		StatusCode:  "OK",
+		SpanAttributes: map[string]string{
+			"gen_ai.operation.name":  "invoke_agent",
+			"gen_ai.conversation.id": sessionID,
+			"gen_ai.input.messages":  `[{"role":"user","parts":[{"type":"text","content":"hello from copilot"}]}]`,
+		},
+	}}); err != nil {
+		t.Fatalf("failed to insert copilot spans: %v", err)
+	}
+
+	req := httptest.NewRequest(http.MethodGet, "/api/sessions/"+sessionID+"/transcript", nil)
+	rctx := chi.NewRouteContext()
+	rctx.URLParams.Add("sessionId", sessionID)
+	req = req.WithContext(context.WithValue(req.Context(), chi.RouteCtxKey, rctx))
+
+	rec := httptest.NewRecorder()
+	h.GetSessionTranscript(rec, req)
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("expected status 200, got %d: %s", rec.Code, rec.Body.String())
+	}
+
+	var resp api.TranscriptResponse
+	if err := json.NewDecoder(rec.Body).Decode(&resp); err != nil {
+		t.Fatalf("failed to decode response: %v", err)
+	}
+	if resp.SessionID != sessionID {
+		t.Fatalf("expected session %q, got %q", sessionID, resp.SessionID)
+	}
+	if len(resp.Messages) == 0 || resp.Messages[0].Role != "user" {
+		t.Fatalf("expected reconstructed user message, got %+v", resp.Messages)
+	}
+}

backend/internal/otlp/logs.go

@@ -3,6 +3,7 @@ package otlp
 import (
 	"encoding/json"
 	"strconv"
+	"strings"
 	"time"
 
 	"github.com/tobilg/ai-observer/internal/api"
@@ -35,6 +36,9 @@ func ConvertLogs(req *collogspb.ExportLogsServiceRequest) LogConversionResult {
 
 			for _, lr := range sl.GetLogRecords() {
 				logAttrs := convertAttributes(lr.GetAttributes())
+				if eventName := strings.TrimSpace(lr.GetEventName()); eventName != "" && logAttrs["event.name"] == "" {
+					logAttrs["event.name"] = eventName
+				}
 
 				// Resolve timestamp with fallbacks before creating log record
 				timestamp := nanosToTime(lr.GetTimeUnixNano())

backend/internal/otlp/logs_test.go

@@ -384,3 +384,50 @@ func TestConvertLogs_CodexSSEEvent_NonResponseCompleted_NoMetrics(t *testing.T)
 		t.Errorf("Expected 0 derived metrics for chunk event, got %d", len(result.DerivedMetrics))
 	}
 }
+
+func TestConvertLogs_PreservesProtoEventName(t *testing.T) {
+	payload := `{
+		"resourceLogs": [{
+			"resource": {
+				"attributes": [
+					{"key": "service.name", "value": {"stringValue": "copilot-chat"}}
+				]
+			},
+			"scopeLogs": [{
+				"scope": {"name": "copilot-chat"},
+				"logRecords": [
+					{
+						"timeUnixNano": "1703500000000000000",
+						"severityNumber": 9,
+						"eventName": "copilot_chat.session.start",
+						"body": {"stringValue": "copilot_chat.session.start"},
+						"attributes": [
+							{"key": "session.id", "value": {"stringValue": "conv-123"}}
+						]
+					}
+				]
+			}]
+		}]
+	}`
+
+	decoder, err := GetDecoder("application/json")
+	if err != nil {
+		t.Fatalf("Failed to get decoder: %v", err)
+	}
+
+	req, err := decoder.DecodeLogs(strings.NewReader(payload))
+	if err != nil {
+		t.Fatalf("Failed to decode logs: %v", err)
+	}
+
+	result := ConvertLogs(req)
+	if len(result.Logs) != 1 {
+		t.Fatalf("Expected 1 log record, got %d", len(result.Logs))
+	}
+	if got := result.Logs[0].LogAttributes["event.name"]; got != "copilot_chat.session.start" {
+		t.Fatalf("expected event.name from proto EventName, got %q", got)
+	}
+	if got := result.Logs[0].LogAttributes["session.id"]; got != "conv-123" {
+		t.Fatalf("expected session.id conv-123, got %q", got)
+	}
+}