Summary

Phase 4 of graph memory (#1222): non-blocking background extraction wired into the agent loop, with TUI spinner support.

Depends on: #1223 (Arc-wrap prerequisite), #1226 (retrieval)

Tasks

1. Background Extraction in SemanticMemory

Add to SemanticMemory:

• spawn_graph_extraction(message: &str, context: &[Message], episode_id: MessageId) — spawns tokio::spawn with tokio::time::timeout(extraction_timeout_secs). The spawned task clones Arc<EmbeddingStore>, AnyProvider (already Clone), SqlitePool (already Clone). On timeout or error, logs warning and silently degrades.

2. Agent Loop Integration

In crates/zeph-core/src/agent/persistence.rs:

• After remember_with_parts() stores a user message, call spawn_graph_extraction() if config.memory.graph.enabled.
• Tool output messages (save_only()) are NOT extracted (too noisy, low entity density).

In crates/zeph-core/src/agent/context.rs:

• In the FuturesUnordered context preparation (from refactor(memory): Arc-wrap EmbeddingStore and FuturesUnordered context preparation #1223 refactor), add a GraphFacts fetcher gated by #[cfg(feature = "graph-memory")].
• Call graph_recall() from Phase 3.
• Inject as system message with GRAPH_FACTS_PREFIX at appropriate position.

3. TUI Status Spinner

When graph extraction is running in background:

• Set status: "Extracting entities..." with spinner
• On completion: clear status (or show "Extracted 3 entities, 5 edges")
• Use existing StatusUpdate channel pattern from TUI

4. Extraction Counter Persistence

Increment extraction_count in graph_metadata table after each successful extraction. Used by Phase 5 to trigger community refresh when count % community_refresh_interval == 0.

Architecture Reference

See .local/plan/graph-memory-architecture.md Section 6 for Arc-wrapping details, spawning pattern, and context builder integration.

Acceptance Criteria

• Background extraction does not block agent response
• Extraction timeout (15s default) degrades gracefully (warning log, no error to user)
• TUI shows extraction spinner during processing
• Tool output messages skipped (not extracted)
• Extraction counter persisted in graph_metadata
• Graph facts appear in context when entities exist
• ~13 tests (10 unit + 3 integration)