fix issues

docs/02_components/12_route_chunk_manager/route_chunk_manager_spec.md

@@ -53,12 +53,8 @@ class IRouteChunkManager(ABC):
         pass
     
     @abstractmethod
-    def merge_chunks(self, chunk_id_1: str, chunk_id_2: str, transform: Sim3Transform) -> bool:
-        pass
-    
-    @abstractmethod
-    def get_merge_target(self, chunk_id: str) -> str:
-        """Returns target chunk_id for merging. Returns 'main' for main trajectory."""
+    def merge_chunks(self, target_chunk_id: str, source_chunk_id: str, transform: Sim3Transform) -> bool:
+        """Merges source_chunk INTO target_chunk. Result is stored in target_chunk."""
         pass
     
     @abstractmethod
@@ -468,17 +464,17 @@ bool: True if deactivated successfully
 
 ---
 
-### `merge_chunks(chunk_id_1: str, chunk_id_2: str, transform: Sim3Transform) -> bool`
+### `merge_chunks(target_chunk_id: str, source_chunk_id: str, transform: Sim3Transform) -> bool`
 
-**Description**: Coordinates chunk merging by validating chunks, calling F10 for factor graph merge, and updating chunk states.
+**Description**: Merges source_chunk INTO target_chunk. The resulting merged chunk is target_chunk. Source chunk is deactivated after merge.
 
 **Called By**:
 - F11 Failure Recovery Coordinator (after successful chunk matching)
 
 **Input**:
 ```python
-chunk_id_1: str  # Source chunk (typically newer, to be merged)
-chunk_id_2: str  # Target chunk (typically older, merged into)
+target_chunk_id: str  # Target chunk (receives the merge, typically older/main)
+source_chunk_id: str  # Source chunk (being merged in, typically newer)
 transform: Sim3Transform:
     translation: np.ndarray  # (3,)
     rotation: np.ndarray  # (3, 3) or quaternion
@@ -492,34 +488,33 @@ bool: True if merge successful
 
 **Processing Flow**:
 1. Verify both chunks exist
-2. Verify chunk_id_1 is anchored (has_anchor=True)
+2. Verify source_chunk_id is anchored (has_anchor=True)
 3. Validate chunks can be merged (not already merged, not same chunk)
-4. **Merge direction**: chunk_id_1 (newer, source) merges INTO chunk_id_2 (older, target)
-5. Call F10.merge_chunks(chunk_id_1, chunk_id_2, transform)
-6. Update chunk_id_1 state:
+4. Call F10.merge_chunk_subgraphs(flight_id, source_chunk_id, target_chunk_id, transform)
+5. Update source_chunk_id state:
    - Set is_active=False
    - Set matching_status="merged"
-   - Call deactivate_chunk(chunk_id_1)
-7. Update chunk_id_2 state (if needed)
-8. Persist chunk state via F03 Flight Database.save_chunk_state()
-9. Return True
+   - Call deactivate_chunk(source_chunk_id)
+6. target_chunk remains active (now contains merged frames)
+7. Persist chunk state via F03 Flight Database.save_chunk_state()
+8. Return True
+
+**Merge Convention**:
+- `merge_chunks(target, source)` → source is merged INTO target
+- Result is stored in target_chunk
+- source_chunk is deactivated after merge
+- Example: `merge_chunks("main", "chunk_3")` merges chunk_3 into main trajectory
 
 **Validation**:
 - Both chunks must exist
-- chunk_id_1 must be anchored
-- chunk_id_1 must not already be merged
-- chunk_id_1 and chunk_id_2 must be different
-
-**Merge Direction**:
-- **chunk_id_1**: Source chunk (newer, recently anchored)
-- **chunk_id_2**: Target chunk (older, main trajectory or previous chunk)
-- Newer chunks merge INTO older chunks to maintain chronological consistency
+- source_chunk must be anchored
+- source_chunk must not already be merged
+- target_chunk and source_chunk must be different
 
 **Test Cases**:
-1. **Merge anchored chunks**: Chunks merged successfully, chunk_id_1 deactivated
-2. **Merge unanchored chunk**: Returns False (validation fails)
-3. **Merge already merged chunk**: Returns False (validation fails)
-4. **State updates**: chunk_id_1 marked as merged and deactivated
+1. **Merge anchored chunk**: source_chunk merged into target_chunk
+2. **Source deactivated**: source_chunk marked as merged and deactivated
+3. **Target unchanged**: target_chunk remains active with new frames
 
 ---