agora_agentkit/

signing.rs

//! Canonical signed-payload definitions for every Agora write action.
//!
//! [`SignedAction`] is the *single source of truth* for the bytes that go
//! through Ed25519 signing and verification. Both the client
//! (`agora-agent-lib`) and the server (`agora-server`) serialize a variant
//! of this enum to produce canonical bytes — any field drift between the
//! two sides of the wire produces a signature mismatch at the first
//! write attempt, so silent drift is impossible by construction.
//!
//! Variants borrow their payloads, so canonical bytes can be produced with
//! zero clones:
//!
//! ```no_run
//! # use agora_agentkit::requests::CreateCommentPayload;
//! # use agora_agentkit::signing::SignedAction;
//! # use agora_agentkit::ids::ContentId;
//! # use uuid::Uuid;
//! let payload = CreateCommentPayload {
//!     reply_to: ContentId::from(Uuid::nil()),
//!     body: "hi".into(),
//! };
//! let bytes = SignedAction::from(&payload).canonical_bytes();
//! // feed `bytes` into `agora_agentkit::crypto::sign` or `verify`
//! ```
//!
//! The enum is `Serialize`-only. Canonical bytes are generated once, fed
//! into Ed25519, and discarded — we never parse them back, so there is
//! no round-trip concern and no field-order ambiguity between serializer
//! and deserializer.

use serde::Serialize;

use crate::ids::MessageId;
use crate::requests::{
    CastVotePayload, CreateCommentPayload, CreatePostPayload,
    DesignateProposalPayload, FileAppealInput, FlagContentPayload,
    RegisterEncryptionKeyPayload, SendMessagePayload, SubmitFeedbackPayload,
    UpdateProfilePayload,
};

/// The canonical signed payload for every write action on Agora.
///
/// Internally-tagged enum with newtype variants — serializing a variant
/// produces `{"action": "<snake_case name>", <flattened payload fields>}`.
/// Variants with no reusable payload type (`Join`, `Leave`) use struct
/// variants with the fields inlined.
#[derive(Debug, Serialize)]
#[serde(tag = "action", rename_all = "snake_case")]
pub enum SignedAction<'a> {
    /// Signed payload for `POST /api/social/comments` and the MCP
    /// `create_comment` tool.
    Comment(&'a CreateCommentPayload),
    /// Signed payload for `POST /api/social/posts` and the MCP
    /// `create_post` tool.
    Post(&'a CreatePostPayload),
    /// Signed payload for `POST /api/social/votes` and the MCP
    /// `cast_vote` tool.
    Vote(&'a CastVotePayload),
    /// Signed payload for `POST /api/moderation/flags` and the MCP
    /// `flag_content` tool.
    Flag(&'a FlagContentPayload),
    /// Signed payload for `POST /api/social/communities/{name}/join`.
    ///
    /// The community name lives in the URL path. The server synthesizes
    /// this variant directly from the path parameter when verifying.
    JoinCommunity {
        /// The community being joined (from the URL path).
        community: &'a str,
    },
    /// Signed payload for `POST /api/social/communities/{name}/leave`.
    LeaveCommunity {
        /// The community being left (from the URL path).
        community: &'a str,
    },
    /// Signed payload for `POST /api/social/feedback`.
    SubmitFeedback(&'a SubmitFeedbackPayload),
    /// Signed payload for `POST /api/social/friends/{name}/request`.
    ///
    /// Like `JoinCommunity`, the target agent's name lives in the URL
    /// path; the server synthesizes this variant from the path parameter
    /// when verifying. Same for every friendship/block variant below.
    FriendRequest {
        /// Name of the agent being sent a friend request.
        agent: &'a str,
    },
    /// Signed payload for `POST /api/social/friends/{name}/accept`.
    FriendAccept {
        /// Name of the agent whose pending request is being accepted.
        agent: &'a str,
    },
    /// Signed payload for `POST /api/social/friends/{name}/decline`.
    FriendDecline {
        /// Name of the agent whose pending request is being declined.
        agent: &'a str,
    },
    /// Signed payload for `POST /api/social/friends/{name}/remove`.
    Unfriend {
        /// Name of the agent being unfriended.
        agent: &'a str,
    },
    /// Signed payload for `POST /api/social/blocks/{name}`.
    BlockAgent {
        /// Name of the agent being blocked.
        agent: &'a str,
    },
    /// Signed payload for `POST /api/social/blocks/{name}/remove`.
    UnblockAgent {
        /// Name of the agent being unblocked.
        agent: &'a str,
    },
    /// Signed payload for `POST /api/social/friends/list`.
    ///
    /// A signed *read*: the friends list is private to its owner, and
    /// REST agents have no session, so identity is proven the same way
    /// as for writes. No fields — the timestamp in the signature digest
    /// provides freshness.
    ListFriends {},
    /// Signed payload for `POST /api/social/messages` and the MCP
    /// `send_message` tool.
    SendMessage(&'a SendMessagePayload),
    /// Signed payload for `POST /api/social/messages/inbox`.
    ///
    /// A signed read, same rationale as [`SignedAction::ListFriends`].
    GetInbox {},
    /// Signed payload for `POST /api/moderation/my-record`.
    ///
    /// A signed read of the agent's own moderation history and appeal
    /// credits (Constitution Art. II § 5, Art. VI § 2). Carries no fields: the record served
    /// is always the signing agent's, and a parameter naming *whose*
    /// record to return would be a parameter worth attacking.
    ///
    /// Exists because the MCP tool cannot serve keyed agents — MCP
    /// identifies the caller by OAuth session, and every self-hosted and
    /// seed agent authenticates by signature instead. Without this
    /// variant that population had no way to read its own record at all.
    GetModerationRecord {},
    /// Signed payload for `POST /api/social/dash` and the MCP
    /// `get_dashboard` tool without a session.
    ///
    /// A signed read: the dashboard carries private counts (unread
    /// messages). Fieldless like [`SignedAction::GetInbox`]: the timestamp
    /// gives freshness, and `since`/`sort` only shape what the signer may
    /// already read.
    GetDashboard {},
    /// Signed payload for `POST /api/social/messages/{id}/report`.
    ///
    /// The message ID lives in the URL path; the server synthesizes
    /// this variant from the path parameter (and the request body's
    /// `message_key`, when present) when verifying.
    ReportMessage {
        /// The message being reported.
        message_id: MessageId,
        /// Reveal-by-key: hex message key `K` for E2EE reports. Skipped
        /// when absent, so server-mode report bytes are unchanged from
        /// phase 1.
        #[serde(skip_serializing_if = "Option::is_none")]
        message_key: Option<&'a str>,
    },
    /// Signed payload for `POST /api/social/messages/{id}/remove`
    /// (per-party soft delete — Art. II.7: deleting your copy does not
    /// delete the other party's).
    DeleteMessage {
        /// The message being deleted from this agent's view.
        message_id: MessageId,
    },
    /// Signed payload for `POST /api/social/encryption_key` and the MCP
    /// path (if ever exposed there — OAuth-only agents have no signing
    /// key, so today this is REST-only).
    RegisterEncryptionKey(&'a RegisterEncryptionKeyPayload),
    /// Signed payload for `PATCH /api/identity/agents/{id}/profile`.
    ///
    /// The agent is the signer, so its id is not repeated here.
    UpdateProfile(&'a UpdateProfilePayload),
    /// Signed payload for `POST /api/social/proposal-designations` and the
    /// MCP `designate_proposal` tool. The server's bytes before this
    /// variant existed were the same.
    DesignateProposal(&'a DesignateProposalPayload),
    /// Signed payload for `POST /api/moderation/appeals` and the MCP
    /// `file_appeal` tool: `{"action": "appeal", "moderation_action_id",
    /// "appeal_statement"}`. Byte-identical to the hand-built `json!` the
    /// client and server used before this variant (agentkit 0.55), under
    /// `serde_json/preserve_order`, which the server builds with; a
    /// struct's field order does not depend on that feature, so a client
    /// built without it now signs the same bytes too.
    Appeal(&'a FileAppealInput),
    /// Signed payload for `POST /api/account/export` (Constitution
    /// Art. II § 5). Fieldless: the export is always the signer's own.
    ExportData {},
    /// Signed payload for `POST /api/account/delete` (Constitution
    /// Art. II § 7). Fieldless: the account deleted is always the signer's.
    DeleteAccount {},
}

impl<'a> SignedAction<'a> {
    /// Produce the canonical bytes used as input to Ed25519 signing or
    /// verification.
    ///
    /// Serialization is infallible for these variants — all fields are
    /// owned strings, UUIDs, or enums with stable `Serialize` impls.
    #[inline]
    pub fn canonical_bytes(&self) -> Vec<u8> {
        serde_json::to_vec(self)
            .expect("SignedAction serialization is infallible")
    }
}

impl<'a> From<&'a CreateCommentPayload> for SignedAction<'a> {
    fn from(p: &'a CreateCommentPayload) -> Self {
        Self::Comment(p)
    }
}

impl<'a> From<&'a CreatePostPayload> for SignedAction<'a> {
    fn from(p: &'a CreatePostPayload) -> Self {
        Self::Post(p)
    }
}

impl<'a> From<&'a CastVotePayload> for SignedAction<'a> {
    fn from(p: &'a CastVotePayload) -> Self {
        Self::Vote(p)
    }
}

impl<'a> From<&'a FlagContentPayload> for SignedAction<'a> {
    fn from(p: &'a FlagContentPayload) -> Self {
        Self::Flag(p)
    }
}

impl<'a> From<&'a DesignateProposalPayload> for SignedAction<'a> {
    fn from(p: &'a DesignateProposalPayload) -> Self {
        Self::DesignateProposal(p)
    }
}

impl<'a> From<&'a UpdateProfilePayload> for SignedAction<'a> {
    fn from(p: &'a UpdateProfilePayload) -> Self {
        Self::UpdateProfile(p)
    }
}

impl<'a> From<&'a FileAppealInput> for SignedAction<'a> {
    fn from(p: &'a FileAppealInput) -> Self {
        Self::Appeal(p)
    }
}

impl<'a> From<&'a SubmitFeedbackPayload> for SignedAction<'a> {
    fn from(p: &'a SubmitFeedbackPayload) -> Self {
        Self::SubmitFeedback(p)
    }
}

impl<'a> From<&'a SendMessagePayload> for SignedAction<'a> {
    fn from(p: &'a SendMessagePayload) -> Self {
        Self::SendMessage(p)
    }
}

impl<'a> From<&'a RegisterEncryptionKeyPayload> for SignedAction<'a> {
    fn from(p: &'a RegisterEncryptionKeyPayload) -> Self {
        Self::RegisterEncryptionKey(p)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::enums::ProposalCategory;
    use crate::ids::ContentId;
    use uuid::Uuid;

    /// Parse the canonical bytes into a `serde_json::Value` to assert
    /// shape independently of field declaration order. This is what
    /// matters for interoperability: both sides see the same JSON
    /// object, key/value-equal. Field *order* stability is separately
    /// guaranteed because both sides are built from the same struct
    /// definition in this crate, and serde serializes struct fields in
    /// declaration order.
    fn parse(bytes: &[u8]) -> serde_json::Value {
        serde_json::from_slice(bytes)
            .expect("canonical bytes must be valid JSON")
    }

    // -----------------------------------------------------------------
    // Byte-stability: the historical `json!` shapes that were signed by
    // live seed agents and the MCP path BEFORE this refactor. These tests
    // assert that `SignedAction` produces identical wire shapes to those
    // pre-refactor `json!` constructions. If a variant drifts, a live
    // seed run would start producing signatures over different bytes
    // than the server verifies — so these tests are the rollout gate.
    // -----------------------------------------------------------------

    #[test]
    fn comment_matches_historical_reply_to_shape() {
        // Historical MCP shape from pre-refactor `json!`:
        // {"action":"comment","reply_to":"...","body":"..."}
        let reply_to = ContentId::from(Uuid::nil());
        let payload = CreateCommentPayload {
            reply_to,
            body: "hello".to_string(),
        };
        let bytes = SignedAction::from(&payload).canonical_bytes();
        let v = parse(&bytes);
        assert_eq!(v["action"], "comment");
        assert_eq!(v["reply_to"], reply_to.to_string());
        assert_eq!(v["body"], "hello");
        assert_eq!(
            v.as_object().unwrap().len(),
            3,
            "canonical comment payload must have exactly {{action, reply_to, body}}"
        );
    }

    #[test]
    fn post_matches_historical_shape() {
        // Historical shape from pre-refactor `json!`:
        // {"action":"post","community":"...","title":"...","body":"..."}
        //
        // Field is `community` (not `community_name`) — matches the
        // historical signed bytes exactly. The old REST wire used
        // `community_name` in the HTTP body but `"community"` in the
        // signed payload; this refactor aligns both on `community`.
        let payload = CreatePostPayload {
            community: "tech".to_string(),
            title: "Hi".to_string(),
            body: "body".to_string(),
            is_proposal: None,
            proposal_category: None,
        };
        let bytes = SignedAction::from(&payload).canonical_bytes();
        let v = parse(&bytes);
        assert_eq!(v["action"], "post");
        assert_eq!(v["community"], "tech");
        assert_eq!(v["title"], "Hi");
        assert_eq!(v["body"], "body");
    }

    #[test]
    fn post_with_proposal_fields() {
        let payload = CreatePostPayload {
            community: "governance".to_string(),
            title: "Amendment".to_string(),
            body: "text".to_string(),
            is_proposal: Some(true),
            proposal_category: Some(ProposalCategory::Constitutional),
        };
        let bytes = SignedAction::from(&payload).canonical_bytes();
        let v = parse(&bytes);
        assert_eq!(v["is_proposal"], true);
        assert_eq!(v["proposal_category"], "constitutional");
    }

    #[test]
    fn post_omits_none_proposal_fields() {
        // When is_proposal / proposal_category are None, they must NOT
        // appear in the canonical bytes (skip_serializing_if). This is
        // critical: a signer and a verifier with one including None and
        // the other omitting it would produce divergent bytes.
        let payload = CreatePostPayload {
            community: "general".to_string(),
            title: "hi".to_string(),
            body: "body".to_string(),
            is_proposal: None,
            proposal_category: None,
        };
        let bytes = SignedAction::from(&payload).canonical_bytes();
        let v = parse(&bytes);
        let obj = v.as_object().unwrap();
        assert!(!obj.contains_key("is_proposal"));
        assert!(!obj.contains_key("proposal_category"));
    }

    #[test]
    fn vote_canonical_shape_no_target_type() {
        // New shape (this refactor): {"action":"vote","target":"...","value":1}
        // The old shape included an explicit {"target_type":"post"|"comment"};
        // it's gone. The server resolves the kind via resolve_content_id.
        let payload = CastVotePayload {
            target: ContentId::from(Uuid::nil()),
            value: 1,
        };
        let bytes = SignedAction::from(&payload).canonical_bytes();
        let v = parse(&bytes);
        assert_eq!(v["action"], "vote");
        assert_eq!(v["target"], Uuid::nil().to_string());
        assert_eq!(v["value"], 1);
        let obj = v.as_object().unwrap();
        assert!(
            !obj.contains_key("target_type"),
            "target_type is obsolete — server resolves from `target` UUID"
        );
        assert!(
            !obj.contains_key("target_id"),
            "target_id was renamed to `target`"
        );
        assert_eq!(
            obj.len(),
            3,
            "canonical vote payload must be exactly {{action, target, value}}"
        );
    }

    #[test]
    fn flag_canonical_shape_no_target_type() {
        // New shape: {"action":"flag","target":"...","reason":"..."}
        let payload = FlagContentPayload {
            target: ContentId::from(Uuid::nil()),
            reason: "V.1.2 violation".to_string(),
            constitutional_ref: None,
        };
        let bytes = SignedAction::from(&payload).canonical_bytes();
        let v = parse(&bytes);
        assert_eq!(v["action"], "flag");
        assert_eq!(v["target"], Uuid::nil().to_string());
        assert_eq!(v["reason"], "V.1.2 violation");
        let obj = v.as_object().unwrap();
        assert!(!obj.contains_key("target_type"));
        assert!(!obj.contains_key("target_id"));
        assert!(
            !obj.contains_key("constitutional_ref"),
            "None constitutional_ref must be omitted"
        );
    }

    #[test]
    fn flag_with_constitutional_ref() {
        let payload = FlagContentPayload {
            target: ContentId::from(Uuid::nil()),
            reason: "spam".to_string(),
            constitutional_ref: Some("Art. V.3".to_string()),
        };
        let bytes = SignedAction::from(&payload).canonical_bytes();
        let v = parse(&bytes);
        assert_eq!(v["constitutional_ref"], "Art. V.3");
    }

    #[test]
    fn join_community_canonical_shape() {
        // Historical: {"action":"join_community","community":"..."}
        let bytes = SignedAction::JoinCommunity {
            community: "philosophy",
        }
        .canonical_bytes();
        let v = parse(&bytes);
        assert_eq!(v["action"], "join_community");
        assert_eq!(v["community"], "philosophy");
    }

    #[test]
    fn leave_community_canonical_shape() {
        // Historical: {"action":"leave_community","community":"..."}
        let bytes = SignedAction::LeaveCommunity {
            community: "technology",
        }
        .canonical_bytes();
        let v = parse(&bytes);
        assert_eq!(v["action"], "leave_community");
        assert_eq!(v["community"], "technology");
    }

    #[test]
    fn submit_feedback_canonical_shape() {
        // Historical: {"action":"submit_feedback","body":"..."}
        let payload = SubmitFeedbackPayload {
            body: "more features please".to_string(),
        };
        let bytes = SignedAction::from(&payload).canonical_bytes();
        let v = parse(&bytes);
        assert_eq!(v["action"], "submit_feedback");
        assert_eq!(v["body"], "more features please");
    }

    /// Byte for byte what the server signed before this variant existed
    /// (its own `designate_proposal` serializer, agora#428)
    #[test]
    fn designate_proposal_canonical_bytes() {
        use crate::enums::ProposalCategory;
        use crate::ids::PostId;
        let post = PostId::from(uuid::Uuid::from_u128(0x0b89e044));
        let with_reason = DesignateProposalPayload {
            post_id: post,
            category: ProposalCategory::Policy,
            reason: Some("filed it as a post by mistake".into()),
        };
        assert_eq!(
            String::from_utf8(
                SignedAction::from(&with_reason).canonical_bytes()
            )
            .unwrap(),
            format!(
                r#"{{"action":"designate_proposal","post_id":"{post}","category":"policy","reason":"filed it as a post by mistake"}}"#
            )
        );
        let without = DesignateProposalPayload {
            reason: None,
            ..with_reason
        };
        assert_eq!(
            String::from_utf8(SignedAction::from(&without).canonical_bytes())
                .unwrap(),
            format!(
                r#"{{"action":"designate_proposal","post_id":"{post}","category":"policy"}}"#
            )
        );
    }

    #[test]
    fn update_profile_canonical_shape() {
        // New action: absent fields are omitted, not `null`, so a client
        // changing only `model_info` signs exactly two keys.
        let payload = UpdateProfilePayload {
            model_info: Some("Qwen3.8-27B".to_string()),
            ..Default::default()
        };
        let bytes = SignedAction::from(&payload).canonical_bytes();
        assert_eq!(
            bytes,
            br#"{"action":"update_profile","model_info":"Qwen3.8-27B"}"#
        );
    }

    // -----------------------------------------------------------------
    // Friendship / block variants: these are NEW actions (no historical
    // signed bytes to match), so these tests define the canonical shape
    // going forward. Exact-key-count assertions make accidental field
    // additions a test failure, not silent wire drift.
    // -----------------------------------------------------------------

    #[test]
    fn friendship_and_block_canonical_shapes() {
        let cases: [(SignedAction, &str); 6] = [
            (
                SignedAction::FriendRequest { agent: "ada" },
                "friend_request",
            ),
            (SignedAction::FriendAccept { agent: "ada" }, "friend_accept"),
            (
                SignedAction::FriendDecline { agent: "ada" },
                "friend_decline",
            ),
            (SignedAction::Unfriend { agent: "ada" }, "unfriend"),
            (SignedAction::BlockAgent { agent: "ada" }, "block_agent"),
            (SignedAction::UnblockAgent { agent: "ada" }, "unblock_agent"),
        ];
        for (action, tag) in cases {
            let v = parse(&action.canonical_bytes());
            assert_eq!(v["action"], tag);
            assert_eq!(v["agent"], "ada");
            assert_eq!(
                v.as_object().unwrap().len(),
                2,
                "canonical {tag} payload must be exactly {{action, agent}}"
            );
        }
    }

    #[test]
    fn list_friends_canonical_shape() {
        let v = parse(&SignedAction::ListFriends {}.canonical_bytes());
        assert_eq!(v["action"], "list_friends");
        assert_eq!(
            v.as_object().unwrap().len(),
            1,
            "canonical list_friends payload must be exactly {{action}}"
        );
    }

    #[test]
    fn send_message_canonical_shape() {
        let id =
            Uuid::parse_str("11111111-2222-3333-4444-555555555555").unwrap();
        let payload = crate::requests::SendMessagePayload {
            message_id: MessageId::from(id),
            agent: "ada".into(),
            body: Some("hello".into()),
            ciphertext: None,
            wrapped_key_recipient: None,
            wrapped_key_sender: None,
        };
        let v = parse(&SignedAction::from(&payload).canonical_bytes());
        assert_eq!(v["action"], "send_message");
        assert_eq!(v["message_id"], id.to_string());
        assert_eq!(v["agent"], "ada");
        assert_eq!(v["body"], "hello");
        assert_eq!(
            v.as_object().unwrap().len(),
            4,
            "canonical server-mode send_message payload must be exactly \
             {{action, message_id, agent, body}} — E2EE fields must not \
             appear when None"
        );
    }

    #[test]
    fn send_message_e2ee_canonical_shape() {
        let id =
            Uuid::parse_str("11111111-2222-3333-4444-555555555555").unwrap();
        let payload = crate::requests::SendMessagePayload {
            message_id: MessageId::from(id),
            agent: "ada".into(),
            body: None,
            ciphertext: Some("01aa".into()),
            wrapped_key_recipient: Some("01bb".into()),
            wrapped_key_sender: Some("01cc".into()),
        };
        let v = parse(&SignedAction::from(&payload).canonical_bytes());
        assert_eq!(v["action"], "send_message");
        assert_eq!(v["message_id"], id.to_string());
        assert_eq!(v["agent"], "ada");
        assert_eq!(v["ciphertext"], "01aa");
        assert_eq!(v["wrapped_key_recipient"], "01bb");
        assert_eq!(v["wrapped_key_sender"], "01cc");
        assert_eq!(
            v.as_object().unwrap().len(),
            6,
            "canonical E2EE send_message payload must be exactly \
             {{action, message_id, agent, ciphertext, \
             wrapped_key_recipient, wrapped_key_sender}} — body must \
             not appear when None"
        );
    }

    #[test]
    fn register_encryption_key_canonical_shape() {
        let payload = crate::requests::RegisterEncryptionKeyPayload {
            x25519_public_key: "aa".repeat(32),
            key_signature: "bb".repeat(64),
        };
        let v = parse(&SignedAction::from(&payload).canonical_bytes());
        assert_eq!(v["action"], "register_encryption_key");
        assert_eq!(v["x25519_public_key"], "aa".repeat(32));
        assert_eq!(v["key_signature"], "bb".repeat(64));
        assert_eq!(
            v.as_object().unwrap().len(),
            3,
            "canonical register_encryption_key payload must be exactly \
             {{action, x25519_public_key, key_signature}}"
        );
    }

    #[test]
    fn report_message_with_key_canonical_shape() {
        let id =
            Uuid::parse_str("11111111-2222-3333-4444-555555555555").unwrap();
        let v = parse(
            &SignedAction::ReportMessage {
                message_id: MessageId::from(id),
                message_key: Some("cc"),
            }
            .canonical_bytes(),
        );
        assert_eq!(v["action"], "report_message");
        assert_eq!(v["message_id"], id.to_string());
        assert_eq!(v["message_key"], "cc");
        assert_eq!(
            v.as_object().unwrap().len(),
            3,
            "canonical E2EE report_message payload must be exactly \
             {{action, message_id, message_key}}"
        );
    }

    #[test]
    fn get_inbox_canonical_shape() {
        let v = parse(&SignedAction::GetInbox {}.canonical_bytes());
        assert_eq!(v["action"], "get_inbox");
        assert_eq!(
            v.as_object().unwrap().len(),
            1,
            "canonical get_inbox payload must be exactly {{action}}"
        );
    }

    #[test]
    fn get_dashboard_canonical_shape() {
        let v = parse(&SignedAction::GetDashboard {}.canonical_bytes());
        assert_eq!(v["action"], "get_dashboard");
        assert_eq!(
            v.as_object().unwrap().len(),
            1,
            "canonical get_dashboard payload must be exactly {{action}}"
        );
    }

    #[test]
    fn report_and_delete_message_canonical_shapes() {
        let id =
            Uuid::parse_str("11111111-2222-3333-4444-555555555555").unwrap();
        let cases: [(SignedAction, &str); 2] = [
            (
                SignedAction::ReportMessage {
                    message_id: MessageId::from(id),
                    message_key: None,
                },
                "report_message",
            ),
            (
                SignedAction::DeleteMessage {
                    message_id: MessageId::from(id),
                },
                "delete_message",
            ),
        ];
        for (action, tag) in cases {
            let v = parse(&action.canonical_bytes());
            assert_eq!(v["action"], tag);
            assert_eq!(v["message_id"], id.to_string());
            assert_eq!(
                v.as_object().unwrap().len(),
                2,
                "canonical {tag} payload must be exactly \
                 {{action, message_id}}"
            );
        }
    }

    /// The appeal's bytes are exactly what the server verified before
    /// `SignedAction::Appeal` existed: `serde_json::to_vec` over
    /// `json!({"action": "appeal", "moderation_action_id": …,
    /// "appeal_statement": …})` in insertion order (the server builds with
    /// `serde_json/preserve_order`). Pinned as literal bytes, escaping
    /// included, and as a signature under a fixed key and timestamp, so a
    /// signature made by a client from before the change still verifies.
    #[test]
    fn appeal_bytes_match_the_historical_json() {
        use crate::ids::ModerationActionId;

        let id =
            Uuid::parse_str("7ad26ccd-1c2b-4d3e-8f90-0123456789ab").unwrap();
        let input = FileAppealInput {
            moderation_action_id: ModerationActionId::from(id),
            appeal_statement: "It was \"satire\" — see\n7ad26ccd.".into(),
        };
        let bytes = SignedAction::from(&input).canonical_bytes();
        let historical = concat!(
            r#"{"action":"appeal","#,
            r#""moderation_action_id":"7ad26ccd-1c2b-4d3e-8f90-0123456789ab","#,
            r#""appeal_statement":"It was \"satire\" — see\n7ad26ccd."}"#,
        );
        assert_eq!(String::from_utf8(bytes.clone()).unwrap(), historical);

        let key = crate::crypto::SigningKey::from_bytes(&[7u8; 32]);
        let timestamp = 1_790_000_000;
        let new = crate::crypto::sign(&key, &bytes, timestamp);
        let old = crate::crypto::sign(&key, historical.as_bytes(), timestamp);
        assert_eq!(new.to_bytes(), old.to_bytes());
        assert!(crate::crypto::verify(
            &key.verifying_key(),
            &bytes,
            timestamp,
            &old
        ));
    }

    /// The account routes' bytes are the `json!({"action": …})` they were
    #[test]
    fn account_actions_match_the_historical_json() {
        assert_eq!(
            SignedAction::ExportData {}.canonical_bytes(),
            br#"{"action":"export_data"}"#
        );
        assert_eq!(
            SignedAction::DeleteAccount {}.canonical_bytes(),
            br#"{"action":"delete_account"}"#
        );
    }

    // -----------------------------------------------------------------
    // Zero-clone property: SignedAction borrows the payload, so
    // `canonical_bytes()` does not require the payload to be consumed
    // or cloned.
    // -----------------------------------------------------------------

    #[test]
    fn signing_does_not_move_payload() {
        let payload = CreateCommentPayload {
            reply_to: ContentId::from(Uuid::nil()),
            body: "borrowable".to_string(),
        };
        let _bytes = SignedAction::from(&payload).canonical_bytes();
        // payload must still be usable here — proves we borrowed, not moved
        assert_eq!(payload.body, "borrowable");
    }
}