feat: segment observation history by controller identity (closes #23)

src/fenris/collector.py

@@ -124,6 +124,20 @@ def acquire_from_sysfs(sysfs_path: Path) -> Dict[str, Any]:
     else:
         identity["transport"] = None
     
+    # vid/ssvid from PCI node (optional, metadata only - never key components)
+    # PCI device directory is the sysfs_path itself (the controller dir is a symlink to PCI)
+    pci_device = sysfs_path
+    for attr, key in [("vendor", "vid"), ("subsystem_vendor", "ssvid")]:
+        filepath = pci_device / attr
+        if filepath.exists():
+            try:
+                value = filepath.read_text().strip()
+                identity[key] = value if value else None
+            except Exception:
+                identity[key] = None
+        else:
+            identity[key] = None
+    
     return identity
 
 
@@ -180,18 +194,34 @@ def write_sample(
     identity: Dict[str, Any],
     conn: sqlite3.Connection,
     clock,
-) -> None:
+) -> Dict[str, Any]:
     """Write one sample to the observation store.
     
     Identity normalization happens exactly once here.
+    Returns segment info for the caller.
     """
+    from .segment import find_current_segment, should_open_new_segment, open_segment
+    
     # Normalize identity exactly once at write time
     identity_key = normalize_identity(identity)
     identity_degraded = compute_identity_degraded(identity)
     
-    # TODO: Implement full sample writing with controller segment handling
-    # For now, just insert a basic sample with identity fields
+    # Find current segment
+    current_segment = find_current_segment(conn)
     
+    # Determine if we need a new segment
+    should_open, reason = should_open_new_segment(
+        current_segment, identity_key, sample["bytes_written"], conn
+    )
+    
+    # Open new segment if needed
+    segment_opened = False
+    if should_open:
+        now = clock.utcnow()
+        open_segment(conn, now, identity, identity_key, identity_degraded)
+        segment_opened = True
+    
+    # Insert sample
     cursor = conn.execute(
         """
         INSERT INTO samples (
@@ -226,6 +256,13 @@ def write_sample(
     )
     
     conn.commit()
+    
+    return {
+        "segment_opened": segment_opened,
+        "segment_reason": reason,
+        "identity_key": identity_key,
+        "identity_degraded": identity_degraded,
+    }
 
 
 def run_collection(