How are Firestore document reads counted for devices with a snapshot listener query?

I'm trying to understand the read charges from Firestore when using a snapshot listener query that excludes devices already listed in the downloadedBy field. Here’s the initial Firestore state:

JSONCopied
{
  "doc1": {"downloadedBy": ["device12345","device2468"]},  // Downloaded by Device 1 and 3
  "doc2": {"downloadedBy": ["device12345","device2468"]},  // Downloaded by Device 1 and 3
  ...
  "doc101": {"downloadedBy": ["device2468"]},  // Downloaded by device 3
  "doc102": {"downloadedBy": []}  // Newly added
}

For each device, the scenario is as follows:

• Device 1 (device12345): Downloads doc101 and doc102 then updates Firestore, adding device12345 to their downloadedBy field.
• Device 2 (device67890): Receives documents doc1 through doc102 because none list device67890.
• Device 3 (device2468): Receives document doc102 only, because it’s not yet in its downloadedBy field.

The query attached to the listener is:

PYTHONCopied
def on_snapshot(doc_snapshot, changes, read_time):
    for change in changes:
        if change.type.name == "ADDED":
            print(f"New document added: {change.document.id}")
        elif change.type.name == "MODIFIED":
            print(f"Document modified: {change.document.id}")
        elif change.type.name == "REMOVED":
            print(f"Document removed: {change.document.id}")

device_id = "device12345"  # Replace with your actual device ID
user_id = "your_user_id"  # Replace with the actual user ID

# Reference the subcollection and attach the listener
query = db.collection("PAD").document(user_id).collection("Field").where("downloadedBy", "not-in", [device_id])

According to the logic:

• Device 1 (device12345): Initial Reads: 2 documents; Subsequent Reads: None if no new matching documents (Total Reads = 2).
• Device 2 (device67890): Initial Reads: 102 documents; Subsequent Reads: None if no new matching documents (Total Reads = 102).
• Device 3 (device2468): Initial Reads: 1 document (doc102); Subsequent Reads: None if no new matching documents (Total Reads = 1).

I'm looking for confirmation that this is how Firestore counts the document reads using snapshot listeners in this scenario.