Constant SHIELDED_STORAGE_BYTES_PER_ACTION 

pub const SHIELDED_STORAGE_BYTES_PER_ACTION: u64 = 312;

Permanent storage bytes per shielded action: 312 bytes total.

• 280 bytes in the BulkAppendTree: 32 (cmx, the note commitment) + 32 (rho) + 216 (the encrypted note ciphertext).
• 32 bytes in the nullifier tree.

The 216-byte encrypted note is Orchard’s TransmittedNoteCiphertext, laid out as epk(32) || enc_ciphertext(104) || out_ciphertext(80):

• epk (32): the note’s ephemeral public key, published in the clear. The recipient combines it with their incoming viewing key (Diffie–Hellman) to derive the AEAD key.
• enc_ciphertext (104): the note encrypted to the recipient (opened with the incoming viewing key) — ChaCha20-Poly1305 over the note plaintext. It holds the compact note (52 = version 1 + diversifier d 11 + value 8 + rseed 32), the memo (36), and the AEAD tag (16); the 52-byte compact prefix is what wallets trial-decrypt during sync to detect their own notes.
• out_ciphertext (80): the note encrypted to the sender for wallet recovery (opened with the outgoing viewing key): out plaintext (64 = pk_d 32 + esk 32) + AEAD tag (16).

This is the standard Orchard layout except the memo is 36 bytes (DashMemo) instead of Zcash’s 512 — the dashpay orchard fork makes the memo size a type parameter (MemoSize) — which is why each note is 216 bytes (ENCRYPTED_NOTE_SIZE) rather than Zcash Orchard’s ~692.