feat(coderd): return log snapshot for paused tasks (#21771)

Previously the task logs endpoint only worked when the workspace was running, leaving users unable to view task history after pausing. This change adds snapshot retrieval with state-based branching: active tasks fetch live logs from AgentAPI, paused/initializing/pending tasks return stored snapshots (providing continuity during pause/resume), and error/unknown states return HTTP 409 Conflict. The response includes snapshot metadata (snapshot, snapshot_at) to indicate whether logs are live or historical. Closes coder/internal#1254
2026-09-24 15:04:27 +08:00 · 2026-01-30 16:09:45 +02:00
parent 536bca7ea9
commit 21eabb1d73
8 changed files with 432 additions and 33 deletions
@@ -786,6 +786,30 @@ func (api *API) taskSend(rw http.ResponseWriter, r *http.Request) {
 	rw.WriteHeader(http.StatusNoContent)
 }

+// convertAgentAPIMessagesToLogEntries converts AgentAPI messages to
+// TaskLogEntry format.
+func convertAgentAPIMessagesToLogEntries(messages []agentapisdk.Message) ([]codersdk.TaskLogEntry, error) {
+	logs := make([]codersdk.TaskLogEntry, 0, len(messages))
+	for _, m := range messages {
+		var typ codersdk.TaskLogType
+		switch m.Role {
+		case agentapisdk.RoleUser:
+			typ = codersdk.TaskLogTypeInput
+		case agentapisdk.RoleAgent:
+			typ = codersdk.TaskLogTypeOutput
+		default:
+			return nil, xerrors.Errorf("invalid agentapi message role %q", m.Role)
+		}
+		logs = append(logs, codersdk.TaskLogEntry{
+			ID:      int(m.Id),
+			Content: m.Content,
+			Type:    typ,
+			Time:    m.Time,
+		})
+	}
+	return logs, nil
+}
+
 // @Summary Get AI task logs
 // @ID get-ai-task-logs
 // @Security CoderSessionToken
@@ -799,8 +823,42 @@ func (api *API) taskLogs(rw http.ResponseWriter, r *http.Request) {
 	ctx := r.Context()
 	task := httpmw.TaskParam(r)

+	switch task.Status {
+	case database.TaskStatusActive:
+		// Active tasks: fetch live logs from AgentAPI.
+		out, err := api.fetchLiveTaskLogs(r, task)
+		if err != nil {
+			httperror.WriteResponseError(ctx, rw, err)
+			return
+		}
+
+		httpapi.Write(ctx, rw, http.StatusOK, out)
+
+	case database.TaskStatusPaused, database.TaskStatusPending, database.TaskStatusInitializing:
+		// In pause, pending and initializing states, we attempt to fetch
+		// the snapshot from database to provide continuity.
+		out, err := api.fetchSnapshotTaskLogs(ctx, task.ID)
+		if err != nil {
+			httperror.WriteResponseError(ctx, rw, err)
+			return
+		}
+
+		httpapi.Write(ctx, rw, http.StatusOK, out)
+
+	default:
+		// Cases: database.TaskStatusError, database.TaskStatusUnknown.
+		// - Error: snapshot would be stale from previous pause.
+		// - Unknown: cannot determine reliable state.
+		httpapi.Write(ctx, rw, http.StatusConflict, codersdk.Response{
+			Message: "Cannot fetch logs for task in current state.",
+			Detail:  fmt.Sprintf("Task status is %q.", task.Status),
+		})
+	}
+}
+
+func (api *API) fetchLiveTaskLogs(r *http.Request, task database.Task) (codersdk.TaskLogsResponse, error) {
 	var out codersdk.TaskLogsResponse
-	if err := api.authAndDoWithTaskAppClient(r, task, func(ctx context.Context, client *http.Client, appURL *url.URL) error {
+	err := api.authAndDoWithTaskAppClient(r, task, func(ctx context.Context, client *http.Client, appURL *url.URL) error {
 		agentAPIClient, err := agentapisdk.NewClient(appURL.String(), agentapisdk.WithHTTPClient(client))
 		if err != nil {
 			return httperror.NewResponseError(http.StatusBadGateway, codersdk.Response{
@@ -817,35 +875,89 @@ func (api *API) taskLogs(rw http.ResponseWriter, r *http.Request) {
 			})
 		}

-		logs := make([]codersdk.TaskLogEntry, 0, len(messagesResp.Messages))
-		for _, m := range messagesResp.Messages {
-			var typ codersdk.TaskLogType
-			switch m.Role {
-			case agentapisdk.RoleUser:
-				typ = codersdk.TaskLogTypeInput
-			case agentapisdk.RoleAgent:
-				typ = codersdk.TaskLogTypeOutput
-			default:
-				return httperror.NewResponseError(http.StatusBadGateway, codersdk.Response{
-					Message: "Invalid task app response message role.",
-					Detail:  fmt.Sprintf(`Expected "user" or "agent", got %q.`, m.Role),
-				})
-			}
-			logs = append(logs, codersdk.TaskLogEntry{
-				ID:      int(m.Id),
-				Content: m.Content,
-				Type:    typ,
-				Time:    m.Time,
+		logs, err := convertAgentAPIMessagesToLogEntries(messagesResp.Messages)
+		if err != nil {
+			return httperror.NewResponseError(http.StatusBadGateway, codersdk.Response{
+				Message: "Invalid task app response.",
+				Detail:  err.Error(),
 			})
 		}
-		out = codersdk.TaskLogsResponse{Logs: logs}
+
+		out = codersdk.TaskLogsResponse{
+			Logs: logs,
+		}
 		return nil
-	}); err != nil {
-		httperror.WriteResponseError(ctx, rw, err)
-		return
+	})
+	return out, err
+}
+
+func (api *API) fetchSnapshotTaskLogs(ctx context.Context, taskID uuid.UUID) (codersdk.TaskLogsResponse, error) {
+	snapshot, err := api.Database.GetTaskSnapshot(ctx, taskID)
+	if err != nil {
+		if httpapi.IsUnauthorizedError(err) {
+			return codersdk.TaskLogsResponse{}, httperror.NewResponseError(http.StatusNotFound, codersdk.Response{
+				Message: "Resource not found.",
+			})
+		}
+		if errors.Is(err, sql.ErrNoRows) {
+			// No snapshot exists yet, return empty logs. Snapshot is true
+			// because this field indicates whether the data is from the
+			// live task app (false) or not (true). Since the task is
+			// paused/initializing/pending, we cannot fetch live logs, so
+			// snapshot must be true even with no snapshot data.
+			return codersdk.TaskLogsResponse{
+				Logs:     []codersdk.TaskLogEntry{},
+				Snapshot: true,
+			}, nil
+		}
+		return codersdk.TaskLogsResponse{}, httperror.NewResponseError(http.StatusInternalServerError, codersdk.Response{
+			Message: "Internal error fetching task snapshot.",
+			Detail:  err.Error(),
+		})
 	}

-	httpapi.Write(ctx, rw, http.StatusOK, out)
+	// Unmarshal envelope with pre-populated data field to decode once.
+	envelope := TaskLogSnapshotEnvelope{
+		Data: &agentapisdk.GetMessagesResponse{},
+	}
+	if err := json.Unmarshal(snapshot.LogSnapshot, &envelope); err != nil {
+		return codersdk.TaskLogsResponse{}, httperror.NewResponseError(http.StatusInternalServerError, codersdk.Response{
+			Message: "Internal error decoding task snapshot.",
+			Detail:  err.Error(),
+		})
+	}
+
+	// Validate snapshot format.
+	if envelope.Format != "agentapi" {
+		return codersdk.TaskLogsResponse{}, httperror.NewResponseError(http.StatusInternalServerError, codersdk.Response{
+			Message: "Unsupported task snapshot format.",
+			Detail:  fmt.Sprintf("Expected format %q, got %q.", "agentapi", envelope.Format),
+		})
+	}
+
+	// Extract agentapi data from envelope (already decoded into the correct type).
+	messagesResp, ok := envelope.Data.(*agentapisdk.GetMessagesResponse)
+	if !ok {
+		return codersdk.TaskLogsResponse{}, httperror.NewResponseError(http.StatusInternalServerError, codersdk.Response{
+			Message: "Internal error decoding snapshot data.",
+			Detail:  "Unexpected data type in envelope.",
+		})
+	}
+
+	// Convert agentapi messages to log entries.
+	logs, err := convertAgentAPIMessagesToLogEntries(messagesResp.Messages)
+	if err != nil {
+		return codersdk.TaskLogsResponse{}, httperror.NewResponseError(http.StatusInternalServerError, codersdk.Response{
+			Message: "Invalid snapshot data.",
+			Detail:  err.Error(),
+		})
+	}
+
+	return codersdk.TaskLogsResponse{
+		Logs:       logs,
+		Snapshot:   true,
+		SnapshotAt: ptr.Ref(snapshot.LogSnapshotCreatedAt),
+	}, nil
 }

 // authAndDoWithTaskAppClient centralizes the shared logic to: