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PS_AI_Agent/.claude/session_log_2026-02-19.md
j.foucher 302337b573 memory
2026-02-19 15:02:55 +01:00

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Session Log — 2026-02-19

Project: PS_AI_Agent (Unreal Engine 5.5) Machine: Desktop PC (j_foucher) Working directory: E:\ASTERION\GIT\PS_AI_Agent

Conversation Summary

1. Initial Request

User asked to create a plugin to use the ElevenLabs Conversational AI Agent in UE5.5. Reference: existing Convai plugin (gRPC-based, more complex). Goal: simpler version using ElevenLabs. Plugin name requested: PS_AI_Agent_ElevenLabs.

2. Codebase Exploration

Explored the Convai plugin source at ConvAI/Convai/ to understand:

  • Module/settings structure
  • AudioCapture patterns
  • HTTP proxy pattern
  • gRPC streaming architecture (to know what to replace with WebSocket)
  • Convai already had EVoiceType::ElevenLabsVoices — confirming the direction

3. Plugin Created

All source files written from scratch under: Unreal/PS_AI_Agent/Plugins/PS_AI_Agent_ElevenLabs/

Files created:

  • PS_AI_Agent_ElevenLabs.uplugin
  • PS_AI_Agent_ElevenLabs.Build.cs
  • Public/PS_AI_Agent_ElevenLabs.h — Module + UElevenLabsSettings
  • Public/ElevenLabsDefinitions.h — Enums, structs, protocol constants
  • Public/ElevenLabsWebSocketProxy.h + .cpp — WS session manager
  • Public/ElevenLabsConversationalAgentComponent.h + .cpp — Main NPC component
  • Public/ElevenLabsMicrophoneCaptureComponent.h + .cpp — Mic capture
  • PS_AI_Agent.uproject — Plugin registered

Commit: f0055e8

4. Memory Files Created

To allow context recovery on any machine (including laptop):

  • .claude/MEMORY.md — project structure + patterns (auto-loaded by Claude Code)
  • .claude/elevenlabs_plugin.md — plugin file map + API protocol details
  • .claude/project_context.md — original ask, intent, short/long-term goals
  • Local copy also at C:\Users\j_foucher\.claude\projects\...\memory\

Commit: f0055e8 (with plugin), updated in 4d6ae10

5. .gitignore Updated

Added to existing ignores:

  • Unreal/PS_AI_Agent/Plugins/*/Binaries/
  • Unreal/PS_AI_Agent/Plugins/*/Intermediate/
  • Unreal/PS_AI_Agent/*.sln / *.suo
  • .claude/settings.local.json
  • generate_pptx.py

Commit: 4d6ae10, b114ab0

6. Compile — First Attempt (Errors Found)

Ran Build.bat PS_AI_AgentEditor Win64 Development. Errors:

  • WebSockets listed in .uplugin — it's a module not a plugin → removed
  • OpenDefaultCaptureStream doesn't exist in UE 5.5 → use OpenAudioCaptureStream
  • FOnAudioCaptureFunction callback uses const void* not const float* → fixed cast
  • TArray::RemoveAt(0, N, false) deprecated → use EAllowShrinking::No
  • AudioCapture is a plugin and must be in .uplugin Plugins array → added

Commit: bb1a857

7. Compile — Success

Clean build, no warnings, no errors. Output: Plugins/PS_AI_Agent_ElevenLabs/Binaries/Win64/UnrealEditor-PS_AI_Agent_ElevenLabs.dll

Memory updated with confirmed UE 5.5 API patterns. Commit: 3b98edc

8. Documentation — Markdown

Full reference doc written to .claude/PS_AI_Agent_ElevenLabs_Documentation.md:

  • Installation, Project Settings, Quick Start (BP + C++), Components Reference, Data Types, Turn Modes, Security/Signed URL, Audio Pipeline, Common Patterns, Troubleshooting.

Commit: c833ccd

9. Documentation — PowerPoint

20-slide dark-themed PowerPoint generated via Python (python-pptx 1.0.2):

  • File: PS_AI_Agent_ElevenLabs_Documentation.pptx in repo root
  • Covers all sections with visual layout, code blocks, flow diagrams, colour-coded elements
  • Generator script generate_pptx.py excluded from git via .gitignore

Commit: 1b72026

Session 2 — 2026-02-19 (continued context)

10. API vs Implementation Cross-Check (3 bugs found and fixed)

Cross-referenced elevenlabs_api_reference.md against plugin source. Found 3 protocol bugs:

Bug 1 — Transcript fields wrong:

  • Type: "transcript" → "user_transcript"
  • Event key: "transcript_event" → "user_transcription_event"
  • Field: "message" → "user_transcript"

Bug 2 — Pong format wrong:

  • event_id was nested in pong_event{} → must be top-level

Bug 3 — Client turn mode messages don't exist:

  • "user_turn_start" / "user_turn_end" are not valid API types
  • Replaced: start → "user_activity", end → no-op (server detects silence)

Commit: ae2c9b9

11. SendTextMessage Added

User asked for text input to agent for testing (without mic). Added SendTextMessage(FString) to UElevenLabsWebSocketProxy and UElevenLabsConversationalAgentComponent. Sends {"type":"user_message","text":"..."} — agent replies with audio + text.

Commit: b489d11

12. Binary WebSocket Frame Fix

User reported: "Received unexpected binary WebSocket frame" warnings. Root cause: ElevenLabs sends ALL WebSocket frames as binary, never text. OnMessage (text handler) never fires. OnRawMessage must handle everything.

Fix: Implemented OnWsBinaryMessage with fragment reassembly (BinaryFrameBuffer).

Commit: 669c503

13. JSON vs PCM Discrimination Fix

After binary fix: "Failed to parse WebSocket message as JSON" errors. Root cause: Binary frames contain BOTH JSON control messages AND raw PCM audio.

Fix: Peek at byte[0] of assembled buffer:

  • '{' (0x7B) → UTF-8 JSON → route to OnWsMessage()
  • anything else → raw PCM audio → broadcast to OnAudioReceived

Commit: 4834567

14. Documentation Updated to v1.1.0

Full rewrite of .claude/PS_AI_Agent_ElevenLabs_Documentation.md:

  • Added Changelog section (v1.0.0 / v1.1.0)
  • Updated audio pipeline (binary PCM path, not Base64 JSON)
  • Added SendTextMessage to all function tables and examples
  • Corrected turn mode docs, transcript docs, OnAgentConnected timing
  • New troubleshooting entries

Commit: e464cfe

15. Test Blueprint Asset Updated

test_AI_Actor.uasset updated in UE Editor.

Commit: 99017f4

Git History (this session)

Hash Message
f0055e8 Add PS_AI_Agent_ElevenLabs plugin (initial implementation)
4d6ae10 Update .gitignore: exclude plugin build artifacts and local Claude settings
b114ab0 Broaden .gitignore: use glob for all plugin Binaries/Intermediate
bb1a857 Fix compile errors in PS_AI_Agent_ElevenLabs plugin
3b98edc Update memory: document confirmed UE 5.5 API patterns and plugin compile status
c833ccd Add plugin documentation for PS_AI_Agent_ElevenLabs
1b72026 Add PowerPoint documentation and update .gitignore
bbeb429 ElevenLabs API reference doc
dbd6161 TestMap, test actor, DefaultEngine.ini, memory update
ae2c9b9 Fix 3 WebSocket protocol bugs
b489d11 Add SendTextMessage
669c503 Fix binary WebSocket frames
4834567 Fix JSON vs binary frame discrimination
e464cfe Update documentation to v1.1.0
99017f4 Update test_AI_Actor blueprint asset

Key Technical Decisions Made This Session

Decision Reason
WebSocket instead of gRPC ElevenLabs Conversational AI uses WS/JSON; no ThirdParty libs needed
AudioCapture in .uplugin Plugins array It's an engine plugin, not a module — UBT requires it declared
WebSockets in Build.cs only It's a module (no .uplugin file), declaring it in .uplugin causes build error
FOnAudioCaptureFunction uses const void* UE 5.3+ API change — must cast to float* inside callback
EAllowShrinking::No Bool overload of RemoveAt deprecated in UE 5.5
USoundWaveProcedural for playback Allows pushing raw PCM bytes at runtime without file I/O
Silence threshold = 30 ticks ~0.5s at 60fps heuristic to detect agent finished speaking
Binary frame handling ElevenLabs sends ALL WS frames as binary; peek byte[0] to discriminate JSON vs PCM
user_activity for client turn user_turn_start/user_turn_end don't exist in ElevenLabs API

Next Steps (not done yet)

  • Verify mic audio actually reaches ElevenLabs (enable Verbose Logging, test in Editor)
  • Test USoundWaveProcedural underflow behaviour in practice (check for audio glitches)
  • Test SendTextMessage end-to-end in Blueprint
  • Add lip-sync support (future)
  • Add session memory / conversation history (future, matching Convai)
  • Add environment/action context support (future)
  • Consider Signed URL Mode backend implementation