[benesjan]

Implements the rename agreed in governance discussion #52.

This is a pure rename fixing stale terminology (Aztec.nr also uses the new terminology).

Concept	Old	Solidity / TS	Noir
hashed public payload	content	publicContentHash	public_content_hash
L2-side preimage	secret	privateContent (Fr[])	private_content ([Field; N])
its commitment	secretHash	privateContentHash	private_content_hash
hash helper	computeSecretHash / compute_secret_hash	computePrivateContentHash	compute_private_content_hash
domain separator	DOM_SEP__SECRET_HASH ("secret_hash")	DomainSeparator.PRIVATE_CONTENT_HASH	DOM_SEP__PRIVATE_CONTENT_HASH ("private_content_hash")

How this is split

L1 and Noir protocol changes live here; everything in aztec-node goes upstream.

• This PR (foundation): l1-contracts (Inbox, FeeJuicePortal, interfaces, errors, test portals and tests), noir-projects/fnd (the domain separator in constants.nr and its test, the aztec_sublib copy of the L1→L2 helpers, FeeJuice), the regenerated genesis constants, and the labs side carried as labs-patches/0015-refactor-rename-L1-L2-message-content-secret-to-publ.patch so this tree's labs build and tests run against the renamed ABI and separator.
• aztec-node: the same labs diff, rebased on aztec-node main, is refactor!: rename L1->L2 message content/secret to public_content_hash/private_content aztec-labs-eng/aztec-node#689. It can only go green once aztec-node's foundation pin (BB_VERSION in labs-aztec-toolchain/bootstrap.sh) moves to a foundation release that includes this PR. When it merges and this repo bumps the labs gitlink past it, patch 0015 drops out of the series.

Breaking changes

• Protocol: the domain separator string was renamed, so the private content hash value changes. Pending L1→L2 messages whose hash was computed with the old helper cannot be consumed with the new one. FeeJuice hashes with it, so its class id rotates and the genesis constants move (regenerated with noir-projects/fnd/scripts/regenerate_genesis_constants.sh --fixtures; nothing hand-edited).
• L1: Inbox.sendL2Message(_recipient, _publicContentHash, _privateContentHash), L1ToL2Msg struct / MessageSent event fields, Inbox__PublicContentHashTooLarge / Inbox__PrivateContentHashTooLarge (new selectors), FeeJuicePortal.depositToAztecPublic(..., _privateContentHash) and its event, reference TokenPortal / UniswapPortal.
• Aztec.nr (aztec-node): consume_l1_to_l2_message(public_content_hash, private_content, sender, leaf_index), compute_private_content_hash, compute_l1_to_l2_message_{hash,nullifier} params, TXE send_l1_to_l2_message(public_content_hash, private_content: [Field; N], ...) / send_l1_to_l2_message_from_private_content_hash (TXE oracle version bumped). The aztec_sublib copy here follows the same names. FeeJuice.claim / TokenBridge.claim_* keep their secret params (used as the message's private content).
• Aztec.js / stdlib (aztec-node): L1ToL2Message.{publicContentHash,privateContentHash}, computePrivateContentHash(privateContent: Fr[]) (mirrors Noir; computeSecretHash took a single field), computeFeeJuiceMessageNullifier / getNonNullifiedL1ToL2MessageWitness take privateContent: Fr[]. generateClaimSecret removed — use Fr.random() + computePrivateContentHash. L2Claim.claimSecret / claimSecretHash keep their names.
• Bot (aztec-node): crosschain seeds and the inbox bot's persisted messages use the new field names; BotStore.SCHEMA_VERSION 2 → 3, so older stores are discarded on startup.
• CLI (aztec-node): get-l1-to-l2-message-witness --private-content.

Out of scope: L2→L1 messages (L2ToL1Msg.content etc.), TransparentNote.secret_hash (app-level; only its compute_private_content_hash call updated), versioned docs, and this repo's docs/ (pinned to aztec-node's v6 line, which does not carry the rename).

Expected failures

• labs/yarn-project/aztec/src/{mainnet,testnet}_compatibility.test.ts pin what the live networks were deployed with; the FeeJuice class id rotation breaks them until the corresponding governance upgrade. They only run on release branches and were deliberately not touched.