feat: Phase 2.7 identity resolution for gaze/lip trace nodes

Implementation:
- gaze_trace nodes: Query face_trace identity_id, add to properties
- lip_trace nodes: Query face_trace identity_id, add to properties
- Rule2: Extend identity resolution to support gaze_trace/lip_trace node types

Architecture:
- All face-related nodes now have identity_id in TKG properties
- Rule2 unified identity resolution for face_trace/gaze_trace/lip_trace
- TKG-only approach (no face_detections dependency for identity)

Code Changes:
- src/core/processor/tkg.rs: Add identity_id query in gaze/lip builders
- src/core/chunk/rule2_ingest.rs: Extend node_type condition

Docs:
- docs_v1.0/DESIGN/TKG_PHASE2_7_IDENTITY_RESOLUTION.md

Status: Implementation complete, pending test with valid file

docs_v1.0/DESIGN/TKG_PHASE2_7_IDENTITY_RESOLUTION.md

@@ -0,0 +1,165 @@
+---
+title: TKG Phase 2.7 Identity Resolution for Edges
+version: 1.0
+date: 2026-06-21
+author: OpenCode
+status: Draft
+---
+
+## Phase 2.7 Overview
+
+为 gaze_trace 和 lip_trace nodes 添加 identity_id 属性，实现完整的 edge identity resolution。
+
+## Current Implementation Analysis
+
+### Rule2 Identity Resolution
+
+**Location**: `src/core/chunk/rule2_ingest.rs`
+
+**Current Logic** (lines 102-131):
+```rust
+// Only resolves face_trace nodes
+let src_identity: Option<String> = if src_type == "face_trace" {
+    sqlx::query_scalar("SELECT i.name FROM tkg_nodes n
+     JOIN identities i ON i.id = (n.properties->>'identity_id')::bigint
+     WHERE n.node_type = 'face_trace' AND n.properties->>'identity_id' IS NOT NULL")
+}
+```
+
+**Problem**: 
+- Only handles `face_trace` node type
+- `gaze_trace` and `lip_trace` nodes lack identity_id
+
+### Node Type Properties
+
+| Node Type | external_id | identity_id | 状态 |
+|-----------|-------------|-------------|------|
+| **face_trace** | trace_{id} | ✓ 有 | ✅ Phase 2.3 |
+| **gaze_trace** | gaze_{id} | ❌ 无 | 需要添加 |
+| **lip_trace** | lip_{id} | ❌ 无 | 需要添加 |
+
+## Solution Design
+
+### Approach 1: Extend Rule2 Logic (Complex)
+
+修改 Rule2 支持 gaze_trace/lip_trace node types：
+```rust
+let src_identity: Option<String> = if src_type == "face_trace" || src_type == "gaze_trace" || src_type == "lip_trace" {
+    // Parse trace_id from external_id
+    let trace_id = src_ext_id.split('_').last()?;
+    // Query face_trace node
+    sqlx::query_scalar("SELECT i.name FROM tkg_nodes n
+     JOIN identities i ON i.id = (n.properties->>'identity_id')::bigint
+     WHERE n.node_type = 'face_trace' AND n.external_id = 'trace_' || $1")
+    .bind(trace_id)
+}
+```
+
+**优点**: 不需要修改 TKG builders
+**缺点**: Rule2 逻辑复杂，查询效率低
+
+### Approach 2: Add identity_id in TKG Builders (Recommended)
+
+在创建 gaze_trace/lip_trace nodes 时直接设置 identity_id：
+```rust
+// Step 1: Query face_trace node's identity_id
+let face_identity_id: Option<i64> = sqlx::query_scalar(
+    "SELECT (properties->>'identity_id')::bigint FROM tkg_nodes
+     WHERE file_uuid=$1 AND node_type='face_trace' AND external_id=$2"
+)
+.bind(file_uuid)
+.bind(&format!("trace_{}", trace_id))
+.fetch_optional(pool)
+.await?;
+
+// Step 2: Add to gaze/lip node properties
+let props = serde_json::json!({
+    "trace_id": tid,
+    "identity_id": face_identity_id, // <-- NEW
+    ...
+});
+```
+
+**优点**: 
+- 性能最优（一次查询）
+- Rule2 无需修改
+- 逻辑清晰
+
+**缺点**: 需要修改 TKG builders
+
+### Recommended: Approach 2
+
+## Implementation Plan
+
+### Step 1: Modify build_gaze_trace_nodes_from_qdrant()
+
+**Location**: `src/core/processor/tkg.rs:1859-1975`
+
+**Add**:
+```rust
+// Query face_trace identity_id
+let face_ext_id = format!("trace_{}", tid);
+let face_identity_id: Option<i64> = sqlx::query_scalar(&format!(
+    "SELECT (properties->>'identity_id')::bigint FROM {}
+     WHERE file_uuid=$1 AND node_type='face_trace' AND external_id=$2",
+    nodes_table
+))
+.bind(file_uuid)
+.bind(&face_ext_id)
+.fetch_optional(pool)
+.await?;
+
+// Add to properties
+let props = serde_json::json!({
+    "trace_id": tid,
+    "identity_id": face_identity_id, // <-- NEW
+    "frame_count": frame_count,
+    ...
+});
+```
+
+### Step 2: Modify build_lip_trace_nodes_from_qdrant()
+
+**Location**: `src/core/processor/tkg.rs` (lip_trace builder)
+
+**Add**: Same logic as gaze_trace
+
+### Step 3: Update PostgreSQL fallback versions
+
+Also update:
+- `build_gaze_trace_nodes_from_pg()`
+- `build_lip_trace_nodes_from_pg()`
+
+### Step 4: Update Rule2 (Optional)
+
+If desired, extend Rule2 to support gaze_trace/lip_trace:
+```rust
+let src_identity: Option<String> = if src_type == "face_trace" || src_type == "gaze_trace" || src_type == "lip_trace" {
+    // Query identity from node properties
+    ...
+}
+```
+
+**Note**: With Approach 2, Rule2 already works correctly!
+
+## Verification Plan
+
+1. TKG rebuild → check gaze/lip nodes have identity_id
+2. Rule2 test → verify identity resolution works
+3. Edge count comparison → ensure no regression
+4. Performance benchmark → measure impact
+
+## Success Criteria
+
+- [ ] gaze_trace nodes have identity_id in properties
+- [ ] lip_trace nodes have identity_id in properties
+- [ ] Rule2 identity resolution works for all node types
+- [ ] No regressions in edge counts
+- [ ] Performance acceptable (<10ms added)
+
+## Timeline
+
+- Implementation: 1 day
+- Testing: 0.5 day
+- **Total: 1.5 days**
+