diff --git a/Cargo.lock b/Cargo.lock
index 28ea2a8af..8fc232b20 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -9722,16 +9722,20 @@ version = "1.0.0-beta.10"
 dependencies = [
  "flatbuffers",
  "prost 0.14.4",
+ "rmp-serde",
  "rustfs-common",
  "rustfs-config",
  "rustfs-io-metrics",
  "rustfs-tls-runtime",
  "rustfs-utils",
+ "serde",
+ "serde_json",
  "tokio",
  "tonic",
  "tonic-prost",
  "tonic-prost-build",
  "tracing",
+ "uuid",
 ]
 
 [[package]]
diff --git a/crates/protos/Cargo.toml b/crates/protos/Cargo.toml
index 7d9953543..5c568d0c5 100644
--- a/crates/protos/Cargo.toml
+++ b/crates/protos/Cargo.toml
@@ -45,6 +45,12 @@ tonic-prost = { workspace = true }
 tonic-prost-build = { workspace = true }
 tokio = { workspace = true, features = ["sync", "fs", "rt-multi-thread"] }
 tracing = { workspace = true }
+serde = { workspace = true }
+rmp-serde = { workspace = true }
+uuid = { workspace = true }
 
 [lib]
 doctest = false
+
+[dev-dependencies]
+serde_json = { workspace = true }
diff --git a/crates/protos/src/heal_control.rs b/crates/protos/src/heal_control.rs
new file mode 100644
index 000000000..9b09565a0
--- /dev/null
+++ b/crates/protos/src/heal_control.rs
@@ -0,0 +1,833 @@
+// Copyright 2024 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Structural wire codec for heal-control commands.
+//!
+//! Decoding proves only that a payload has a supported, bounded shape. It does
+//! not establish coordinator authority, freshness, or replay protection. The
+//! decoded fields intentionally remain opaque until an execution layer adds
+//! contextual lease and nonce validation.
+
+use rmp_serde::Deserializer;
+use rustfs_common::heal_channel::{
+    HealAdmissionDropReason, HealAdmissionResult, HealChannelPriority, HealChannelRequest, HealChannelResponse,
+    HealRequestSource, HealScanMode,
+};
+use serde::{Deserialize, Serialize, de::SeqAccess, de::Visitor};
+use std::{fmt, io::Cursor, io::Write};
+
+const ENVELOPE_VERSION: u8 = 1;
+pub const ENVELOPE_MAX_SIZE: usize = 64 * 1024;
+pub const NONCE_SIZE: usize = 16;
+pub const MAX_LIFETIME_MS: i64 = 30_000;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct RequestMetadata {
+    pub nonce: [u8; NONCE_SIZE],
+    pub issued_at_unix_ms: i64,
+    pub expires_at_unix_ms: i64,
+    pub coordinator_epoch: u64,
+}
+
+impl RequestMetadata {
+    pub const fn new(nonce: [u8; NONCE_SIZE], issued_at_unix_ms: i64, expires_at_unix_ms: i64, coordinator_epoch: u64) -> Self {
+        Self {
+            nonce,
+            issued_at_unix_ms,
+            expires_at_unix_ms,
+            coordinator_epoch,
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+enum Priority {
+    Low,
+    Normal,
+    High,
+    Critical,
+}
+
+impl From<HealChannelPriority> for Priority {
+    fn from(priority: HealChannelPriority) -> Self {
+        match priority {
+            HealChannelPriority::Low => Self::Low,
+            HealChannelPriority::Normal => Self::Normal,
+            HealChannelPriority::High => Self::High,
+            HealChannelPriority::Critical => Self::Critical,
+        }
+    }
+}
+
+impl From<Priority> for HealChannelPriority {
+    fn from(priority: Priority) -> Self {
+        match priority {
+            Priority::Low => Self::Low,
+            Priority::Normal => Self::Normal,
+            Priority::High => Self::High,
+            Priority::Critical => Self::Critical,
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase", deny_unknown_fields)]
+pub struct StartCommand {
+    disk: Option<String>,
+    bucket: String,
+    object_prefix: Option<String>,
+    object_version_id: Option<String>,
+    force_start: bool,
+    priority: Priority,
+    pool_index: Option<u64>,
+    set_index: Option<u64>,
+    scan_mode: Option<HealScanMode>,
+    remove_corrupted: Option<bool>,
+    recreate_missing: Option<bool>,
+    update_parity: Option<bool>,
+    recursive: Option<bool>,
+    dry_run: Option<bool>,
+    timeout_seconds: Option<u64>,
+    source: HealRequestSource,
+}
+
+impl TryFrom<HealChannelRequest> for StartCommand {
+    type Error = String;
+
+    fn try_from(request: HealChannelRequest) -> Result<Self, Self::Error> {
+        Ok(Self {
+            disk: request.disk,
+            bucket: request.bucket,
+            object_prefix: request.object_prefix,
+            object_version_id: request.object_version_id,
+            force_start: request.force_start,
+            priority: request.priority.into(),
+            pool_index: request
+                .pool_index
+                .map(u64::try_from)
+                .transpose()
+                .map_err(|_| "heal pool index exceeds wire range".to_string())?,
+            set_index: request
+                .set_index
+                .map(u64::try_from)
+                .transpose()
+                .map_err(|_| "heal set index exceeds wire range".to_string())?,
+            scan_mode: request.scan_mode,
+            remove_corrupted: request.remove_corrupted,
+            recreate_missing: request.recreate_missing,
+            update_parity: request.update_parity,
+            recursive: request.recursive,
+            dry_run: request.dry_run,
+            timeout_seconds: request.timeout_seconds,
+            source: request.source,
+        })
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(tag = "action", rename_all = "snake_case", deny_unknown_fields)]
+pub enum Command {
+    Start { request: StartCommand },
+    Query { heal_path: String, client_token: String },
+    Cancel { heal_path: String, client_token: String },
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase", deny_unknown_fields)]
+pub struct Envelope {
+    version: u8,
+    request_id: String,
+    nonce: [u8; NONCE_SIZE],
+    issued_at_unix_ms: i64,
+    expires_at_unix_ms: i64,
+    coordinator_epoch: u64,
+    command: Command,
+}
+
+impl Envelope {
+    fn new(request_id: String, metadata: RequestMetadata, command: Command) -> Result<Self, String> {
+        let envelope = Self {
+            version: ENVELOPE_VERSION,
+            request_id,
+            nonce: metadata.nonce,
+            issued_at_unix_ms: metadata.issued_at_unix_ms,
+            expires_at_unix_ms: metadata.expires_at_unix_ms,
+            coordinator_epoch: metadata.coordinator_epoch,
+            command,
+        };
+        envelope.validate()?;
+        Ok(envelope)
+    }
+
+    pub fn start(request: HealChannelRequest, metadata: RequestMetadata) -> Result<Self, String> {
+        let request_id = request.id.clone();
+        Self::new(
+            request_id,
+            metadata,
+            Command::Start {
+                request: request.try_into()?,
+            },
+        )
+    }
+
+    pub fn query(request_id: String, metadata: RequestMetadata, heal_path: String, client_token: String) -> Result<Self, String> {
+        Self::new(request_id, metadata, Command::Query { heal_path, client_token })
+    }
+
+    pub fn cancel(
+        request_id: String,
+        metadata: RequestMetadata,
+        heal_path: String,
+        client_token: String,
+    ) -> Result<Self, String> {
+        Self::new(request_id, metadata, Command::Cancel { heal_path, client_token })
+    }
+
+    fn validate(&self) -> Result<(), String> {
+        if self.version != ENVELOPE_VERSION {
+            return Err(format!("unsupported heal control envelope version: {}", self.version));
+        }
+        validate_uuid(&self.request_id, "request")?;
+        if self.coordinator_epoch == 0 {
+            return Err("heal control coordinator epoch is zero".to_string());
+        }
+        if self.nonce.iter().all(|byte| *byte == 0) {
+            return Err("heal control nonce is zero".to_string());
+        }
+        if self.issued_at_unix_ms < 0 || self.expires_at_unix_ms <= self.issued_at_unix_ms {
+            return Err("heal control request lifetime is invalid".to_string());
+        }
+        if self.expires_at_unix_ms - self.issued_at_unix_ms > MAX_LIFETIME_MS {
+            return Err("heal control request lifetime exceeds limit".to_string());
+        }
+        match &self.command {
+            Command::Start { .. } => {}
+            Command::Query { client_token, .. } | Command::Cancel { client_token, .. } if client_token.is_empty() => {
+                return Err("heal control client token is empty".to_string());
+            }
+            Command::Query { .. } | Command::Cancel { .. } => {}
+        }
+        Ok(())
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum Admission {
+    Accepted,
+    Merged,
+    Full,
+    DroppedQueueFull,
+    DroppedPolicy,
+}
+
+impl From<HealAdmissionResult> for Admission {
+    fn from(result: HealAdmissionResult) -> Self {
+        match result {
+            HealAdmissionResult::Accepted => Self::Accepted,
+            HealAdmissionResult::Merged => Self::Merged,
+            HealAdmissionResult::Full => Self::Full,
+            HealAdmissionResult::Dropped(HealAdmissionDropReason::QueueFull) => Self::DroppedQueueFull,
+            HealAdmissionResult::Dropped(HealAdmissionDropReason::PolicyDropped) => Self::DroppedPolicy,
+        }
+    }
+}
+
+impl Admission {
+    pub const fn is_admitted(self) -> bool {
+        matches!(self, Self::Accepted | Self::Merged)
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(tag = "result", rename_all = "snake_case", deny_unknown_fields)]
+pub enum Outcome {
+    Start {
+        task_id: String,
+        admission: Admission,
+    },
+    Channel {
+        success: bool,
+        #[serde(deserialize_with = "deserialize_bounded_optional_bytes")]
+        data: Option<Vec<u8>>,
+        error: Option<String>,
+    },
+}
+
+#[derive(Debug)]
+struct BoundedBytes(Vec<u8>);
+struct BoundedBytesVisitor;
+
+impl<'de> Visitor<'de> for BoundedBytesVisitor {
+    type Value = BoundedBytes;
+
+    fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(formatter, "at most {ENVELOPE_MAX_SIZE} bytes")
+    }
+
+    fn visit_seq<A>(self, mut sequence: A) -> Result<Self::Value, A::Error>
+    where
+        A: SeqAccess<'de>,
+    {
+        if sequence.size_hint().is_some_and(|length| length > ENVELOPE_MAX_SIZE) {
+            return Err(serde::de::Error::custom("heal control response data exceeds size limit"));
+        }
+
+        let mut bytes = Vec::new();
+        while let Some(byte) = sequence.next_element()? {
+            if bytes.len() == ENVELOPE_MAX_SIZE {
+                return Err(serde::de::Error::custom("heal control response data exceeds size limit"));
+            }
+            bytes.push(byte);
+        }
+        Ok(BoundedBytes(bytes))
+    }
+}
+
+impl<'de> Deserialize<'de> for BoundedBytes {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        deserializer.deserialize_seq(BoundedBytesVisitor)
+    }
+}
+
+fn deserialize_bounded_optional_bytes<'de, D>(deserializer: D) -> Result<Option<Vec<u8>>, D::Error>
+where
+    D: serde::Deserializer<'de>,
+{
+    Ok(Option::<BoundedBytes>::deserialize(deserializer)?.map(|bytes| bytes.0))
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase", deny_unknown_fields)]
+pub struct ResultEnvelope {
+    version: u8,
+    request_id: String,
+    coordinator_epoch: u64,
+    outcome: Outcome,
+}
+
+impl ResultEnvelope {
+    pub fn new(request_id: String, coordinator_epoch: u64, outcome: Outcome) -> Result<Self, String> {
+        let result = Self {
+            version: ENVELOPE_VERSION,
+            request_id,
+            coordinator_epoch,
+            outcome,
+        };
+        result.validate()?;
+        Ok(result)
+    }
+
+    pub fn channel(request_id: String, coordinator_epoch: u64, response: HealChannelResponse) -> Result<Self, String> {
+        if response.request_id != request_id {
+            return Err("heal control channel response request ID does not match".to_string());
+        }
+        Self::new(
+            request_id,
+            coordinator_epoch,
+            Outcome::Channel {
+                success: response.success,
+                data: response.data,
+                error: response.error,
+            },
+        )
+    }
+
+    fn validate(&self) -> Result<(), String> {
+        if self.version != ENVELOPE_VERSION {
+            return Err(format!("unsupported heal control result version: {}", self.version));
+        }
+        if self.coordinator_epoch == 0 {
+            return Err("heal control result coordinator epoch is zero".to_string());
+        }
+        validate_uuid(&self.request_id, "result request")?;
+        match &self.outcome {
+            Outcome::Start { task_id, .. } => validate_uuid(task_id, "result task")?,
+            Outcome::Channel {
+                success: true,
+                error: Some(_),
+                ..
+            } => {
+                return Err("successful heal control result contains an error".to_string());
+            }
+            Outcome::Channel {
+                success: false,
+                error: None,
+                ..
+            } => {
+                return Err("failed heal control result has no error".to_string());
+            }
+            Outcome::Channel {
+                success: false,
+                data: Some(_),
+                ..
+            } => {
+                return Err("failed heal control result contains data".to_string());
+            }
+            Outcome::Channel {
+                success: false,
+                error: Some(error),
+                ..
+            } if error.is_empty() => {
+                return Err("failed heal control result has an empty error".to_string());
+            }
+            Outcome::Channel { .. } => {}
+        }
+        Ok(())
+    }
+}
+
+fn validate_uuid(value: &str, field: &str) -> Result<(), String> {
+    let parsed = uuid::Uuid::parse_str(value).map_err(|_| format!("heal control {field} ID is not a UUID"))?;
+    if parsed.is_nil() || parsed.to_string() != value {
+        return Err(format!("heal control {field} ID is not canonical"));
+    }
+    Ok(())
+}
+
+fn decode<T: for<'de> Deserialize<'de>>(data: &[u8], value_name: &str) -> Result<T, String> {
+    if data.len() > ENVELOPE_MAX_SIZE {
+        return Err(format!("{value_name} exceeds size limit"));
+    }
+    let mut deserializer = Deserializer::new(Cursor::new(data));
+    let value = T::deserialize(&mut deserializer).map_err(|err| format!("failed to decode {value_name}: {err}"))?;
+    if usize::try_from(deserializer.get_ref().position()).ok() != Some(data.len()) {
+        return Err(format!("{value_name} contains trailing data"));
+    }
+    Ok(value)
+}
+
+pub fn encode_envelope(envelope: &Envelope) -> Result<Vec<u8>, String> {
+    envelope.validate()?;
+    encode_bounded(envelope, "heal control envelope")
+}
+
+pub fn decode_envelope(data: &[u8]) -> Result<Envelope, String> {
+    let envelope: Envelope = decode(data, "heal control envelope")?;
+    envelope.validate()?;
+    Ok(envelope)
+}
+
+pub fn encode_result(result: &ResultEnvelope) -> Result<Vec<u8>, String> {
+    result.validate()?;
+    encode_bounded(result, "heal control result")
+}
+
+pub fn decode_result(data: &[u8]) -> Result<ResultEnvelope, String> {
+    let result: ResultEnvelope = decode(data, "heal control result")?;
+    result.validate()?;
+    Ok(result)
+}
+
+fn encode_bounded(value: &impl Serialize, value_name: &str) -> Result<Vec<u8>, String> {
+    struct BoundedWriter {
+        bytes: Vec<u8>,
+        exceeded: bool,
+    }
+
+    impl Write for BoundedWriter {
+        fn write(&mut self, data: &[u8]) -> std::io::Result<usize> {
+            let remaining = ENVELOPE_MAX_SIZE.saturating_sub(self.bytes.len());
+            if data.len() > remaining {
+                self.exceeded = true;
+                return Err(std::io::Error::other("heal control value exceeds size limit"));
+            }
+            self.bytes.extend_from_slice(data);
+            Ok(data.len())
+        }
+
+        fn flush(&mut self) -> std::io::Result<()> {
+            Ok(())
+        }
+    }
+
+    let mut writer = BoundedWriter {
+        bytes: Vec::with_capacity(1024),
+        exceeded: false,
+    };
+    let result = value.serialize(&mut rmp_serde::Serializer::new(&mut writer).with_struct_map());
+    if writer.exceeded {
+        return Err(format!("{value_name} exceeds size limit"));
+    }
+    result.map_err(|err| format!("failed to encode {value_name}: {err}"))?;
+    Ok(writer.bytes)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{
+        Admission, ENVELOPE_MAX_SIZE, Envelope, Outcome, RequestMetadata, ResultEnvelope, decode_envelope, decode_result,
+    };
+    use rustfs_common::heal_channel::{HealChannelRequest, HealChannelResponse, HealRequestSource};
+    use serde::de::{DeserializeSeed, SeqAccess, Visitor, value::Error as ValueError};
+
+    fn test_request(request_id: String) -> HealChannelRequest {
+        HealChannelRequest {
+            id: request_id,
+            bucket: "bucket".to_string(),
+            object_prefix: Some("prefix".to_string()),
+            pool_index: Some(1),
+            set_index: Some(2),
+            source: HealRequestSource::Admin,
+            ..Default::default()
+        }
+    }
+
+    fn metadata(byte: u8, epoch: u64) -> RequestMetadata {
+        RequestMetadata::new([byte; 16], 1_000, 2_000, epoch)
+    }
+
+    #[test]
+    fn round_trips_all_commands_and_results() {
+        let request_id = uuid::Uuid::new_v4().to_string();
+        let start = Envelope::start(test_request(request_id), metadata(1, 7)).unwrap();
+        let query = Envelope::query(
+            uuid::Uuid::new_v4().to_string(),
+            metadata(2, 7),
+            "bucket/prefix".to_string(),
+            "token".to_string(),
+        )
+        .unwrap();
+        let cancel = Envelope::cancel(
+            uuid::Uuid::new_v4().to_string(),
+            metadata(3, 7),
+            "bucket/prefix".to_string(),
+            "token".to_string(),
+        )
+        .unwrap();
+
+        for envelope in [start, query, cancel] {
+            let encoded = super::encode_envelope(&envelope).unwrap();
+            assert_eq!(decode_envelope(&encoded).unwrap(), envelope);
+        }
+
+        let result = ResultEnvelope::new(
+            uuid::Uuid::new_v4().to_string(),
+            7,
+            Outcome::Start {
+                task_id: uuid::Uuid::new_v4().to_string(),
+                admission: Admission::Merged,
+            },
+        )
+        .unwrap();
+        let encoded = super::encode_result(&result).unwrap();
+        assert_eq!(decode_result(&encoded).unwrap(), result);
+
+        let channel_request_id = uuid::Uuid::new_v4().to_string();
+        let channel = ResultEnvelope::channel(
+            channel_request_id.clone(),
+            7,
+            HealChannelResponse {
+                request_id: channel_request_id,
+                success: true,
+                data: Some(vec![1, 2, 3]),
+                error: None,
+            },
+        )
+        .unwrap();
+        let encoded = super::encode_result(&channel).unwrap();
+        assert_eq!(decode_result(&encoded).unwrap(), channel);
+    }
+
+    #[test]
+    fn v1_query_and_result_wire_fixtures_are_stable() {
+        let request_id = "00112233-4455-6677-8899-aabbccddeeff".to_string();
+        let start = Envelope::start(
+            test_request(request_id.clone()),
+            RequestMetadata::new([0x11; 16], 1_700_000_000_000, 1_700_000_030_000, 9),
+        )
+        .unwrap();
+        let envelope = Envelope::query(
+            request_id.clone(),
+            RequestMetadata::new([0x11; 16], 1_700_000_000_000, 1_700_000_030_000, 9),
+            "bucket/prefix".to_string(),
+            "client-token".to_string(),
+        )
+        .unwrap();
+        let cancel = Envelope::cancel(
+            request_id.clone(),
+            RequestMetadata::new([0x11; 16], 1_700_000_000_000, 1_700_000_030_000, 9),
+            "bucket/prefix".to_string(),
+            "client-token".to_string(),
+        )
+        .unwrap();
+        let start_result = ResultEnvelope::new(
+            request_id.clone(),
+            9,
+            Outcome::Start {
+                task_id: "ffeeddcc-bbaa-9988-7766-554433221100".to_string(),
+                admission: Admission::DroppedPolicy,
+            },
+        )
+        .unwrap();
+        let result = ResultEnvelope::new(
+            request_id,
+            9,
+            Outcome::Channel {
+                success: true,
+                data: Some(vec![1, 2, 3]),
+                error: None,
+            },
+        )
+        .unwrap();
+
+        let envelope_hex = super::encode_envelope(&envelope)
+            .unwrap()
+            .iter()
+            .map(|byte| format!("{byte:02x}"))
+            .collect::<String>();
+        let result_hex = super::encode_result(&result)
+            .unwrap()
+            .iter()
+            .map(|byte| format!("{byte:02x}"))
+            .collect::<String>();
+        let start_hex = super::encode_envelope(&start)
+            .unwrap()
+            .iter()
+            .map(|byte| format!("{byte:02x}"))
+            .collect::<String>();
+        let cancel_hex = super::encode_envelope(&cancel)
+            .unwrap()
+            .iter()
+            .map(|byte| format!("{byte:02x}"))
+            .collect::<String>();
+        let start_result_hex = super::encode_result(&start_result)
+            .unwrap()
+            .iter()
+            .map(|byte| format!("{byte:02x}"))
+            .collect::<String>();
+        assert_eq!(
+            start_hex,
+            "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"
+        );
+        assert_eq!(
+            cancel_hex,
+            "87a776657273696f6e01a9726571756573744964d92430303131323233332d343435352d363637372d383839392d616162626363646465656666a56e6f6e6365dc001011111111111111111111111111111111ae6973737565644174556e69784d73cf0000018bcfe56800af657870697265734174556e69784d73cf0000018bcfe5dd30b0636f6f7264696e61746f7245706f636809a7636f6d6d616e6483a6616374696f6ea663616e63656ca96865616c5f70617468ad6275636b65742f707265666978ac636c69656e745f746f6b656eac636c69656e742d746f6b656e"
+        );
+        assert_eq!(
+            start_result_hex,
+            "84a776657273696f6e01a9726571756573744964d92430303131323233332d343435352d363637372d383839392d616162626363646465656666b0636f6f7264696e61746f7245706f636809a76f7574636f6d6583a6726573756c74a57374617274a77461736b5f6964d92466666565646463632d626261612d393938382d373736362d353534343333323231313030a961646d697373696f6eae64726f707065645f706f6c696379"
+        );
+        assert_eq!(
+            envelope_hex,
+            "87a776657273696f6e01a9726571756573744964d92430303131323233332d343435352d363637372d383839392d616162626363646465656666a56e6f6e6365dc001011111111111111111111111111111111ae6973737565644174556e69784d73cf0000018bcfe56800af657870697265734174556e69784d73cf0000018bcfe5dd30b0636f6f7264696e61746f7245706f636809a7636f6d6d616e6483a6616374696f6ea57175657279a96865616c5f70617468ad6275636b65742f707265666978ac636c69656e745f746f6b656eac636c69656e742d746f6b656e"
+        );
+        assert_eq!(
+            result_hex,
+            "84a776657273696f6e01a9726571756573744964d92430303131323233332d343435352d363637372d383839392d616162626363646465656666b0636f6f7264696e61746f7245706f636809a76f7574636f6d6584a6726573756c74a76368616e6e656ca773756363657373c3a46461746193010203a56572726f72c0"
+        );
+    }
+
+    #[test]
+    fn rejects_invalid_and_untrusted_shapes() {
+        let request_id = uuid::Uuid::new_v4().to_string();
+        assert!(Envelope::start(test_request(request_id.clone()), metadata(0, 7)).is_err());
+        assert!(Envelope::start(test_request(request_id.clone()), metadata(1, 0)).is_err());
+        assert!(Envelope::start(test_request(request_id.clone()), RequestMetadata::new([1; 16], 1_000, 31_001, 7),).is_err());
+        assert!(Envelope::query(request_id.clone(), metadata(1, 7), String::new(), String::new()).is_err());
+        assert!(
+            Envelope::cancel(request_id.clone(), metadata(1, 7), String::new(), String::new())
+                .unwrap_err()
+                .contains("token is empty")
+        );
+
+        let mut noncanonical_request = test_request(request_id.to_uppercase());
+        assert!(Envelope::start(noncanonical_request.clone(), metadata(1, 7)).is_err());
+        noncanonical_request.id = uuid::Uuid::nil().to_string();
+        assert!(Envelope::start(noncanonical_request, metadata(1, 7)).is_err());
+
+        let boundary = RequestMetadata::new([1; 16], 1_000, 1_000 + super::MAX_LIFETIME_MS, 7);
+        assert!(Envelope::start(test_request(request_id.clone()), boundary).is_ok());
+        assert!(
+            Envelope::start(
+                test_request(request_id.clone()),
+                RequestMetadata::new([1; 16], 1_000, 1_001 + super::MAX_LIFETIME_MS, 7),
+            )
+            .is_err()
+        );
+
+        let envelope = Envelope::start(test_request(request_id.clone()), metadata(1, 7)).unwrap();
+        let mut trailing = super::encode_envelope(&envelope).unwrap();
+        trailing.push(0);
+        assert!(decode_envelope(&trailing).unwrap_err().contains("trailing data"));
+        assert!(
+            decode_envelope(&vec![0; ENVELOPE_MAX_SIZE + 1])
+                .unwrap_err()
+                .contains("size limit")
+        );
+
+        let oversized = Envelope::query(
+            uuid::Uuid::new_v4().to_string(),
+            metadata(1, 7),
+            "x".repeat(ENVELOPE_MAX_SIZE),
+            "token".to_string(),
+        )
+        .unwrap();
+        let error = super::encode_envelope(&oversized).unwrap_err();
+        assert!(error.contains("size limit"), "{error}");
+
+        let mut unknown = serde_json::to_value(&envelope).unwrap();
+        unknown
+            .as_object_mut()
+            .unwrap()
+            .insert("unknown".to_string(), serde_json::Value::Bool(true));
+        let unknown = rmp_serde::to_vec_named(&unknown).unwrap();
+        assert!(decode_envelope(&unknown).unwrap_err().contains("unknown field"));
+
+        assert!(
+            ResultEnvelope::channel(
+                uuid::Uuid::new_v4().to_string(),
+                7,
+                HealChannelResponse {
+                    request_id: uuid::Uuid::new_v4().to_string(),
+                    success: true,
+                    data: None,
+                    error: None,
+                },
+            )
+            .unwrap_err()
+            .contains("does not match")
+        );
+
+        assert!(
+            ResultEnvelope::new(
+                request_id.clone(),
+                7,
+                Outcome::Channel {
+                    success: true,
+                    data: None,
+                    error: Some("unexpected".to_string()),
+                },
+            )
+            .is_err()
+        );
+        assert!(
+            ResultEnvelope::new(
+                request_id.clone(),
+                7,
+                Outcome::Channel {
+                    success: false,
+                    data: None,
+                    error: None,
+                },
+            )
+            .unwrap_err()
+            .contains("has no error")
+        );
+        assert!(
+            ResultEnvelope::new(
+                request_id.clone(),
+                0,
+                Outcome::Channel {
+                    success: true,
+                    data: None,
+                    error: None,
+                },
+            )
+            .unwrap_err()
+            .contains("epoch is zero")
+        );
+        assert!(
+            ResultEnvelope::new(
+                "not-a-uuid".to_string(),
+                7,
+                Outcome::Channel {
+                    success: true,
+                    data: None,
+                    error: None,
+                },
+            )
+            .unwrap_err()
+            .contains("not a UUID")
+        );
+        assert!(
+            ResultEnvelope::new(
+                request_id.clone(),
+                7,
+                Outcome::Start {
+                    task_id: "not-a-uuid".to_string(),
+                    admission: Admission::Accepted,
+                },
+            )
+            .unwrap_err()
+            .contains("not a UUID")
+        );
+        assert!(
+            ResultEnvelope::new(
+                request_id.clone(),
+                7,
+                Outcome::Channel {
+                    success: false,
+                    data: Some(vec![1]),
+                    error: Some("failed".to_string()),
+                },
+            )
+            .is_err()
+        );
+        assert!(
+            ResultEnvelope::new(
+                request_id.clone(),
+                7,
+                Outcome::Channel {
+                    success: false,
+                    data: None,
+                    error: Some(String::new()),
+                },
+            )
+            .is_err()
+        );
+
+        let valid_result = ResultEnvelope::new(
+            request_id,
+            7,
+            Outcome::Channel {
+                success: true,
+                data: Some(vec![1]),
+                error: None,
+            },
+        )
+        .unwrap();
+        let mut length_bomb = rmp_serde::to_vec_named(&valid_result).unwrap();
+        let data_key = length_bomb
+            .windows(6)
+            .position(|window| window == b"\xa4data\x91")
+            .expect("fixture must encode data as a one-element array");
+        length_bomb.splice(data_key + 5..=data_key + 5, [0xdd, 0xff, 0xff, 0xff, 0xff]);
+        assert!(decode_result(&length_bomb).is_err());
+
+        struct OversizedHint;
+
+        impl<'de> SeqAccess<'de> for OversizedHint {
+            type Error = ValueError;
+
+            fn next_element_seed<T>(&mut self, _seed: T) -> Result<Option<T::Value>, Self::Error>
+            where
+                T: DeserializeSeed<'de>,
+            {
+                Ok(None)
+            }
+
+            fn size_hint(&self) -> Option<usize> {
+                Some(ENVELOPE_MAX_SIZE + 1)
+            }
+        }
+
+        let error = super::BoundedBytesVisitor.visit_seq(OversizedHint).unwrap_err();
+        assert!(error.to_string().contains("size limit"));
+    }
+}
diff --git a/crates/protos/src/lib.rs b/crates/protos/src/lib.rs
index 50da7d209..2bf93b030 100644
--- a/crates/protos/src/lib.rs
+++ b/crates/protos/src/lib.rs
@@ -16,6 +16,7 @@
 // scoped to that module so generated internals do not relax lints elsewhere.
 #[allow(unsafe_code)]
 mod generated;
+pub mod heal_control;
 mod runtime_sources;
 
 use proto_gen::node_service::node_service_client::NodeServiceClient;