feat(adk): Go runtime conversation-history compaction

go/adk/cmd/main.go

@@ -178,11 +178,18 @@ func main() {
 		logger.Info("Memory service enabled", "appName", appName)
 	}
 
-	runnerConfig, subagentSessionIDs, err := runnerpkg.CreateRunnerConfig(ctx, agentConfig, sessionService, appName, memoryService)
+	runnerConfig, subagentSessionIDs, compactionCfg, err := runnerpkg.CreateRunnerConfig(ctx, agentConfig, sessionService, appName, memoryService)
 	if err != nil {
 		logger.Error(err, "Failed to create Google ADK Runner config")
 		os.Exit(1)
 	}
+	if compactionCfg != nil {
+		logger.Info("Compaction enabled",
+			"interval", compactionCfg.CompactionInterval,
+			"overlap", compactionCfg.OverlapSize,
+			"tokenThreshold", compactionCfg.TokenThreshold,
+		)
+	}
 
 	stream := agentConfig.GetStream()
 	executor := a2a.NewKAgentExecutor(a2a.KAgentExecutorConfig{
@@ -192,6 +199,7 @@ func main() {
 		Stream:             stream,
 		AppName:            appName,
 		Logger:             logger,
+		CompactionConfig:   compactionCfg,
 	})
 
 	// Build the agent card.

go/adk/pkg/a2a/executor.go

@@ -12,6 +12,7 @@ import (
 	"github.com/a2aproject/a2a-go/a2asrv/eventqueue"
 	"github.com/go-logr/logr"
 	"github.com/kagent-dev/kagent/go/adk/pkg/auth"
+	"github.com/kagent-dev/kagent/go/adk/pkg/compaction"
 	"github.com/kagent-dev/kagent/go/adk/pkg/models"
 	"github.com/kagent-dev/kagent/go/adk/pkg/session"
 	"github.com/kagent-dev/kagent/go/adk/pkg/skills"
@@ -37,6 +38,7 @@ type KAgentExecutorConfig struct {
 	AppName            string
 	SkillsDirectory    string
 	Logger             logr.Logger
+	CompactionConfig   *compaction.Config
 }
 
 // KAgentExecutor implements a2asrv.AgentExecutor
@@ -48,6 +50,7 @@ type KAgentExecutor struct {
 	appName            string
 	skillsDirectory    string
 	logger             logr.Logger
+	compactor          *compaction.Compactor
 }
 
 var _ a2asrv.AgentExecutor = (*KAgentExecutor)(nil)
@@ -69,6 +72,7 @@ func NewKAgentExecutor(cfg KAgentExecutorConfig) *KAgentExecutor {
 		appName:            cfg.AppName,
 		skillsDirectory:    skillsDir,
 		logger:             cfg.Logger.WithName("kagent-executor"),
+		compactor:          compaction.New(cfg.CompactionConfig, cfg.Logger),
 	}
 }
 
@@ -355,7 +359,19 @@ func (e *KAgentExecutor) Execute(ctx context.Context, reqCtx *a2asrv.RequestCont
 		}
 	}
 
-	// 11. Emit final event.
+	// 11. Post-invocation compaction (best-effort; never fails the request).
+	if e.compactor != nil && e.sessionService != nil && runErr == nil {
+		liveSess, sessErr := e.sessionService.GetSession(ctx, e.appName, userID, sessionID)
+		if sessErr != nil {
+			e.logger.V(1).Info("Compaction skipped: could not fetch session", "error", sessErr)
+		} else if liveSess != nil {
+			if compactErr := e.compactor.MaybeCompact(ctx, liveSess, e.sessionService, 0); compactErr != nil {
+				e.logger.Error(compactErr, "compaction failed (continuing)")
+			}
+		}
+	}
+
+	// 12. Emit final event.
 	finalMeta := maps.Clone(baseMeta)
 	if invocationID != "" {
 		finalMeta[adka2a.ToA2AMetaKey("invocation_id")] = invocationID