feat(agent): /clear now clears seahorse DB in addition to JSONL

- Add Clear(ctx, sessionKey) to ContextManager interface
- Implement Clear for legacy (JSONL) and seahorse (DB + JSONL)
- Add Engine.ClearSession + Store.ClearConversation
- Fix FTS5 DELETE trigger syntax in schema (was using wrong
  external-content FTS5 syntax; now uses standard DELETE FROM)
- Fix ClearSession to skip sessions never ingested (was creating
  blank conversations record via GetOrCreateConversation)
- Simplify summary_parents DELETE into single OR statement
- Add TestStoreClearConversation unit test

pkg/agent/context_legacy.go

@@ -61,6 +61,16 @@ func (m *legacyContextManager) Ingest(_ context.Context, _ *IngestRequest) error
 	return nil
 }
 
+func (m *legacyContextManager) Clear(_ context.Context, sessionKey string) error {
+	agent := m.al.registry.GetDefaultAgent()
+	if agent == nil || agent.Sessions == nil {
+		return fmt.Errorf("sessions not initialized")
+	}
+	agent.Sessions.SetHistory(sessionKey, []providers.Message{})
+	agent.Sessions.SetSummary(sessionKey, "")
+	return agent.Sessions.Save(sessionKey)
+}
+
 // maybeSummarize triggers summarization if the session history exceeds thresholds.
 // It runs asynchronously in a goroutine.
 func (m *legacyContextManager) maybeSummarize(sessionKey string) {

pkg/agent/context_manager.go

@@ -24,6 +24,10 @@ type ContextManager interface {
 	// Ingest records a message into the ContextManager's own storage.
 	// Called after each message is persisted to session JSONL.
 	Ingest(ctx context.Context, req *IngestRequest) error
+
+	// Clear removes all stored context for a session (messages, summaries, etc.).
+	// Called when the user issues /clear or /reset.
+	Clear(ctx context.Context, sessionKey string) error
 }
 
 // AssembleRequest is the input to Assemble.

pkg/agent/context_manager_test.go

@@ -690,6 +690,7 @@ func (m *noopContextManager) Assemble(_ context.Context, req *AssembleRequest) (
 }
 func (m *noopContextManager) Compact(_ context.Context, _ *CompactRequest) error { return nil }
 func (m *noopContextManager) Ingest(_ context.Context, _ *IngestRequest) error   { return nil }
+func (m *noopContextManager) Clear(_ context.Context, _ string) error            { return nil }
 
 // trackingContextManager tracks call counts for each method.
 type trackingContextManager struct {
@@ -726,6 +727,8 @@ func (m *trackingContextManager) Ingest(_ context.Context, req *IngestRequest) e
 	return nil
 }
 
+func (m *trackingContextManager) Clear(_ context.Context, _ string) error { return nil }
+
 // resetCMRegistry clears the global factory registry and returns a cleanup
 // function that restores the original state after the test.
 func resetCMRegistry() func() {

pkg/agent/context_seahorse.go

@@ -154,6 +154,19 @@ func (m *seahorseContextManager) Ingest(ctx context.Context, req *IngestRequest)
 	return err
 }
 
+// Clear removes all stored context for a session (seahorse DB + JSONL).
+func (m *seahorseContextManager) Clear(ctx context.Context, sessionKey string) error {
+	if err := m.engine.ClearSession(ctx, sessionKey); err != nil {
+		return err
+	}
+	if m.sessions != nil {
+		m.sessions.SetHistory(sessionKey, []providers.Message{})
+		m.sessions.SetSummary(sessionKey, "")
+		return m.sessions.Save(sessionKey)
+	}
+	return nil
+}
+
 // bootstrapSession reconciles JSONL session history into seahorse SQLite.
 func (m *seahorseContextManager) bootstrapSession(ctx context.Context, sessionKey string) {
 	if m.sessions == nil {

pkg/agent/loop.go

@@ -3368,7 +3368,7 @@ func (al *AgentLoop) handleCommand(
 		return "", false
 	}
 
-	rt := al.buildCommandsRuntime(agent, opts)
+	rt := al.buildCommandsRuntime(ctx, agent, opts)
 	executor := commands.NewExecutor(al.cmdRegistry, rt)
 
 	var commandReply string
@@ -3488,7 +3488,11 @@ func (al *AgentLoop) applyExplicitSkillCommand(
 	return true, false, ""
 }
 
-func (al *AgentLoop) buildCommandsRuntime(agent *AgentInstance, opts *processOptions) *commands.Runtime {
+func (al *AgentLoop) buildCommandsRuntime(
+	ctx context.Context,
+	agent *AgentInstance,
+	opts *processOptions,
+) *commands.Runtime {
 	registry := al.GetRegistry()
 	cfg := al.GetConfig()
 	rt := &commands.Runtime{
@@ -3570,14 +3574,7 @@ func (al *AgentLoop) buildCommandsRuntime(agent *AgentInstance, opts *processOpt
 			if opts == nil {
 				return fmt.Errorf("process options not available")
 			}
-			if agent.Sessions == nil {
-				return fmt.Errorf("sessions not initialized for agent")
-			}
-
-			agent.Sessions.SetHistory(opts.SessionKey, make([]providers.Message, 0))
-			agent.Sessions.SetSummary(opts.SessionKey, "")
-			agent.Sessions.Save(opts.SessionKey)
-			return nil
+			return al.contextManager.Clear(ctx, opts.SessionKey)
 		}
 	}
 	return rt