feat(M5-004,M5-005,M5-006,M5-007): session-conversation binding, session:info broadcast, agent creation from TUI, and session metrics (#321)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

apps/gateway/src/agent/agent.service.ts

@@ -23,7 +23,7 @@ import { createFileTools } from './tools/file-tools.js';
 import { createGitTools } from './tools/git-tools.js';
 import { createShellTools } from './tools/shell-tools.js';
 import { createWebTools } from './tools/web-tools.js';
-import type { SessionInfoDto } from './session.dto.js';
+import type { SessionInfoDto, SessionMetrics } from './session.dto.js';
 import { SystemOverrideService } from '../preferences/system-override.service.js';
 import { PreferencesService } from '../preferences/preferences.service.js';
 import { SessionGCService } from '../gc/session-gc.service.js';
@@ -93,6 +93,12 @@ export interface AgentSession {
   allowedTools: string[] | null;
   /** User ID that owns this session, used for preference lookups. */
   userId?: string;
+  /** Agent config ID applied to this session, if any (M5-001). */
+  agentConfigId?: string;
+  /** Human-readable agent name applied to this session, if any (M5-001). */
+  agentName?: string;
+  /** M5-007: per-session metrics. */
+  metrics: SessionMetrics;
 }
 
 @Injectable()
@@ -184,11 +190,13 @@ export class AgentService implements OnModuleDestroy {
     sessionId: string,
     options?: AgentSessionOptions,
   ): Promise<AgentSession> {
-    // Merge DB agent config when agentConfigId is provided
+    // Merge DB agent config when agentConfigId is provided (M5-001)
     let mergedOptions = options;
+    let resolvedAgentName: string | undefined;
     if (options?.agentConfigId) {
       const agentConfig = await this.brain.agents.findById(options.agentConfigId);
       if (agentConfig) {
+        resolvedAgentName = agentConfig.name;
         mergedOptions = {
           provider: options.provider ?? agentConfig.provider,
           modelId: options.modelId ?? agentConfig.model,
@@ -197,6 +205,8 @@ export class AgentService implements OnModuleDestroy {
           sandboxDir: options.sandboxDir,
           isAdmin: options.isAdmin,
           agentConfigId: options.agentConfigId,
+          userId: options.userId,
+          conversationHistory: options.conversationHistory,
         };
         this.logger.log(
           `Merged agent config "${agentConfig.name}" (${agentConfig.id}) into session ${sessionId}`,
@@ -330,6 +340,14 @@ export class AgentService implements OnModuleDestroy {
       sandboxDir,
       allowedTools,
       userId: mergedOptions?.userId,
+      agentConfigId: mergedOptions?.agentConfigId,
+      agentName: resolvedAgentName,
+      metrics: {
+        tokens: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
+        modelSwitches: 0,
+        messageCount: 0,
+        lastActivityAt: new Date().toISOString(),
+      },
     };
 
     this.sessions.set(sessionId, session);
@@ -458,10 +476,12 @@ export class AgentService implements OnModuleDestroy {
       id: s.id,
       provider: s.provider,
       modelId: s.modelId,
+      ...(s.agentName ? { agentName: s.agentName } : {}),
       createdAt: new Date(s.createdAt).toISOString(),
       promptCount: s.promptCount,
       channels: Array.from(s.channels),
       durationMs: now - s.createdAt,
+      metrics: { ...s.metrics },
     }));
   }
 
@@ -472,13 +492,93 @@ export class AgentService implements OnModuleDestroy {
       id: s.id,
       provider: s.provider,
       modelId: s.modelId,
+      ...(s.agentName ? { agentName: s.agentName } : {}),
       createdAt: new Date(s.createdAt).toISOString(),
       promptCount: s.promptCount,
       channels: Array.from(s.channels),
       durationMs: Date.now() - s.createdAt,
+      metrics: { ...s.metrics },
     };
   }
 
+  /**
+   * Record token usage for a session turn (M5-007).
+   * Accumulates tokens across the session lifetime.
+   */
+  recordTokenUsage(
+    sessionId: string,
+    tokens: { input: number; output: number; cacheRead: number; cacheWrite: number; total: number },
+  ): void {
+    const session = this.sessions.get(sessionId);
+    if (!session) return;
+    session.metrics.tokens.input += tokens.input;
+    session.metrics.tokens.output += tokens.output;
+    session.metrics.tokens.cacheRead += tokens.cacheRead;
+    session.metrics.tokens.cacheWrite += tokens.cacheWrite;
+    session.metrics.tokens.total += tokens.total;
+    session.metrics.lastActivityAt = new Date().toISOString();
+  }
+
+  /**
+   * Record a model switch event for a session (M5-007).
+   */
+  recordModelSwitch(sessionId: string): void {
+    const session = this.sessions.get(sessionId);
+    if (!session) return;
+    session.metrics.modelSwitches += 1;
+    session.metrics.lastActivityAt = new Date().toISOString();
+  }
+
+  /**
+   * Increment message count for a session (M5-007).
+   */
+  recordMessage(sessionId: string): void {
+    const session = this.sessions.get(sessionId);
+    if (!session) return;
+    session.metrics.messageCount += 1;
+    session.metrics.lastActivityAt = new Date().toISOString();
+  }
+
+  /**
+   * Update the model tracked on a live session (M5-002).
+   * This records the model change in the session metadata so subsequent
+   * session:info emissions reflect the new model.  The Pi session itself is
+   * not reconstructed — the model is used on the next createSession call for
+   * the same conversationId when the session is torn down or a new one is created.
+   */
+  updateSessionModel(sessionId: string, modelId: string): void {
+    const session = this.sessions.get(sessionId);
+    if (!session) return;
+    const prev = session.modelId;
+    session.modelId = modelId;
+    this.recordModelSwitch(sessionId);
+    this.logger.log(`Session ${sessionId}: model updated ${prev} → ${modelId} (M5-002)`);
+  }
+
+  /**
+   * Apply a new agent config to a live session mid-conversation (M5-003).
+   * Updates agentName, agentConfigId, and modelId on the session object.
+   * System prompt and tools take effect when the next session is created for
+   * this conversationId (they are baked in at session creation time).
+   */
+  applyAgentConfig(
+    sessionId: string,
+    agentConfigId: string,
+    agentName: string,
+    modelId?: string,
+  ): void {
+    const session = this.sessions.get(sessionId);
+    if (!session) return;
+    session.agentConfigId = agentConfigId;
+    session.agentName = agentName;
+    if (modelId) {
+      this.updateSessionModel(sessionId, modelId);
+    }
+    this.logger.log(
+      `Session ${sessionId}: agent switched to "${agentName}" (${agentConfigId}) (M5-003)`,
+    );
+  }
+
   addChannel(sessionId: string, channel: string): void {
     const session = this.sessions.get(sessionId);
     if (session) {