🐛 Bugfix: Clicking a backend-sourced session in the Vitto chat sidebar...

Date: 2026-02-21
Time: 22:03:02 UTC
Session: gspace1-133.20
Agent: angular
Confidence: 97%
Status: ✅ Documented

📋 Decision Context

Question:

Clicking a backend-sourced session in the Vitto chat sidebar does nothing — the active session does not switch. The user sees the session list (loaded from /ai-api/sessions) but clicking any item has no visible effect.

Task: Fix session switching in Vitto chat sidebar — backend sessions were unclickable

🎯 Decision Made

Chosen:

Change the constructor effect() to check mergedSessions() instead of state().sessions when validating the active session

Options Considered:

1. Copy backend sessions into local autoFlashState on load so they exist in state().sessions
2. Change the constructor effect() to check mergedSessions() instead of state().sessions when validating the active session
3. Add a guard flag to skip the effect when switchSession is called externally
4. Remove the constructor effect entirely and rely on explicit session management

💭 Reasoning

ROOT CAUSE: The constructor effect() in VittoChatPersistenceService validated the active session by checking s.sessions[s.activeSessionId] — which only contains LOCAL sessions stored in autoFlashState. Backend sessions (fetched from /ai-api/sessions/my/history) are stored in a separate _backendSessions signal and merged via mergedSessions() computed. The race condition: (1) User clicks backend session → switchSession(backendId) sets state().activeSessionId = backendId. (2) state() change triggers the effect to re-run. (3) Effect checks s.sessions[backendId] → undefined (backend session not in local state). (4) Effect treats this as 'no valid active session' and overwrites activeSessionId back to the most recent LOCAL session. FIX: Replace s.sessions[s.activeSessionId] with all[s.activeSessionId] where all = this.mergedSessions(), so the effect recognizes both local and backend sessions. This is the minimal, correct fix because: (a) mergedSessions() already exists and is the authoritative source used by sessionList, activeSession, and switchSession; (b) copying backend sessions to local state would create duplication and persistence overhead; (c) guard flags are fragile and create hidden coupling; (d) removing the effect breaks scope-change handling.

📁 Files Involved

• libs/libs-ai/vitto-chat/src/lib/services/vitto-chat-persistence.service.ts
• libs/libs-ai/vitto-chat/src/lib/services/vitto-chat-engine.service.ts
• libs/libs-ai/vitto-chat/src/lib/components/chat-shell/chat-shell.component.ts

🔗 Related

• Decision ID: dev_1771711382203_858u64h
• Session: 133
• Workspace: gspace1

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