feat(agent): add performance fixes and artist variety controls

Add max_tokens limit (1024) to prevent long response generation
eagerly spread same-artist tracks apart using greedy shuffle algorithm

Update system prompt with artist variety rules:
- Default to 1 track per artist for maximum variety
- Only add 2nd track when unique artists exhausted
- Priority: N tracks from N artists > N tracks from fewer artists

Python script improvements:
- Add _shuffle_spread_artists() for playlist ordering
- Add AGENT_MIN_PLAYLIST_TRACKS env var (default: 12)
- Add num_predict: 2048 to prevent response truncation
- Update system prompt with parallel tool calling emphasis

Documentation:
- Update docs/agent.md with new features
- Update backlog task-277 with implementation notes

References: scripts/agent.py as working reference implementation

Author: pythoninthegrass

app/frontend/js/components/genius-browser.js

@@ -8,7 +8,7 @@
 
 import { agent } from '../api/agent.js';
 
-const DEFAULT_MODEL = 'llama3.2:1b';
+const DEFAULT_MODEL = 'qwen3.5:9b';
 
 export function createGeniusBrowser(Alpine) {
   Alpine.data('geniusBrowser', () => ({
@@ -198,10 +198,10 @@ export function createGeniusBrowser(Alpine) {
 
     navigateToPlaylist(playlistId) {
       const sidebar = document.querySelector('[x-data="sidebar"]');
-      if (sidebar && sidebar.__x) {
-        sidebar.__x.$data.loadPlaylist(`playlist-${playlistId}`);
+      const data = sidebar?._x_dataStack?.[0];
+      if (data?.loadPlaylist) {
+        data.loadPlaylist(`playlist-${playlistId}`);
       } else {
-        // Fallback: dispatch event for sidebar to pick up
         window.dispatchEvent(
           new CustomEvent('mt:navigate-playlist', { detail: { playlistId } }),
         );

app/frontend/views/genius.html

@@ -115,7 +115,7 @@ <h3 class="text-sm font-semibold mb-1">Ollama Required</h3>
         <div>
           <h3 class="text-sm font-semibold mb-1">Download AI Model</h3>
           <p class="text-xs text-foreground/50 leading-relaxed">
-            Ollama is running. Download the llama3.2:1b model (~1.3 GB) to enable playlist
+            Ollama is running. Download the qwen3.5:9b model (~6 GB) to enable playlist
             generation.
           </p>
         </div>
@@ -134,7 +134,7 @@ <h3 class="text-sm font-semibold mb-1">Download AI Model</h3>
               >
               </path>
             </svg>
-            Download Model (1.3 GB)
+            Download Model (~6 GB)
           </button>
         </template>
 

backlog/tasks/task-277 - Genius-playlist-creator.md

@@ -4,7 +4,7 @@ title: Genius playlist creator
 status: In Progress
 assignee: []
 created_date: '2026-02-18 05:58'
-updated_date: '2026-03-31 21:27'
+updated_date: '2026-04-02 21:01'
 labels:
   - feature
   - playlists
@@ -226,6 +226,87 @@ Cfg-gate fix: After merging main (which had reverted lastfm discovery methods),
 ## Remaining
 
 - Phase 7: Frontend — Genius sidebar category, prompt UI, onboarding wizard UI
+
+## 2026-04-02: Agent Performance Fixes
+
+### Issues Identified from Logs
+1. **Parallel tool execution not working**: `with_tool_concurrency(8)` was configured but model wasn't calling multiple tools per turn
+2. **Token generation too long**: Final LLM turn took 63 seconds generating ~57 IDs with multiple recounts
+
+### Changes Made
+
+**mod.rs - Agent builder:**
+- Added `.max_tokens(1024)` to cap response length (prevents endless recounting)
+
+**prompt.rs - System prompt:**
+- Enhanced RULES section with explicit parallel tool calling instructions:
+  - "Call MULTIPLE tools PER TURN in PARALLEL"
+  - "When planning your strategy, call ALL independent tools at once"
+
+### Why These Fixes Work
+
+1. **max_tokens(1024)**: Limits the LLM to ~1024 tokens for the final response. The playlist format (name + 25 track IDs) needs only ~200-500 tokens. This prevents the model from generating excessive intermediate reasoning (listing 57 IDs, recounting, selecting, etc.) that was causing the 63-second response time.
+
+2. **Explicit parallel instructions**: The previous prompt mentioned "Call multiple tools per turn" but wasn't emphatic enough. The new language uses ALL CAPS for key concepts and provides concrete examples ("get_similar_artists + search_library + get_track_tags together") to guide the model toward parallel tool calling.
+
+### Test Results
+- All 757 tests pass with `cargo nextest run --workspace --features agent`
+- Both `cargo check --features agent` and `cargo check` compile cleanly
+
+## 2026-04-02: Python Reference Implementation Complete
+
+**Working Solution**: `scripts/agent.py` serves as the reference implementation for the Genius playlist creator.
+
+### Key Features Implemented (Python Script)
+
+1. **8 Agent Tools** - Full implementation matching Rust tool specifications:
+   - `get_recently_played` - Recently played tracks from local library
+   - `get_top_artists` - Top artists by play history
+   - `search_library` - Text search across title/artist/album
+   - `get_similar_tracks` - Last.fm similar tracks, cross-referenced with library
+   - `get_similar_artists` - Last.fm similar artists with library sample tracks
+   - `get_track_tags` - Last.fm mood/genre tags
+   - `get_top_artists_by_tag` - Genre-based artist discovery
+   - `get_top_tracks_by_country` - Regional track discovery
+
+2. **Artist Variety Priority** - System prompt enforces 1 track per artist by default, only adding 2nd tracks when artist diversity is exhausted
+
+3. **Shuffled Playlist Output** - `_shuffle_spread_artists()` uses greedy algorithm to spread same-artist tracks apart
+
+4. **Configurable Track Counts** - Environment variables:
+   - `AGENT_MIN_PLAYLIST_TRACKS` (default: 12)
+   - `AGENT_MAX_PLAYLIST_TRACKS` (default: 25)
+
+5. **Performance Tuning** - `num_predict: 2048` prevents response truncation
+
+### Rust Implementation Notes
+
+The Python script demonstrates the correct behavior for playlist generation:
+- Multi-turn tool calling with parallel execution
+- Last.fm cross-referencing with local library
+- Maximum artist variety (N tracks from N artists)
+- Post-generation shuffle for playback order
+
+When implementing the Rust version, use `scripts/agent.py` as the behavioral reference for:
+- System prompt wording (artist variety rules)
+- Tool response format and hint messages
+- Playlist shuffling algorithm
+- Token limit settings (2048 via `max_tokens`)
+
+### Usage
+
+```bash
+# Default: 12-25 tracks with maximum artist variety
+./scripts/agent.py "make me a chill playlist"
+
+# Custom range: 5-10 tracks
+AGENT_MIN_PLAYLIST_TRACKS=5 AGENT_MAX_PLAYLIST_TRACKS=10 ./scripts/agent.py "quick mix"
+
+# Faster execution with fewer turns
+./scripts/agent.py --max-turns 2 "make me a chill playlist"
+```
+
+Reference file: `scripts/agent.py` (1114 lines, fully functional)
 <!-- SECTION:NOTES:END -->
 
 ## Definition of Done