diff --git a/Cargo.lock b/Cargo.lock
index d690f90..882a9a6 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -391,6 +391,20 @@ dependencies = [
  "tokio",
 ]
 
+[[package]]
+name = "crank-adapter-websocket"
+version = "0.1.0"
+dependencies = [
+ "crank-core",
+ "futures-util",
+ "reqwest",
+ "serde",
+ "serde_json",
+ "thiserror",
+ "tokio",
+ "tokio-tungstenite",
+]
+
 [[package]]
 name = "crank-core"
 version = "0.1.0"
@@ -448,6 +462,7 @@ dependencies = [
  "crank-adapter-graphql",
  "crank-adapter-grpc",
  "crank-adapter-rest",
+ "crank-adapter-websocket",
  "crank-core",
  "crank-mapping",
  "crank-schema",
@@ -456,6 +471,7 @@ dependencies = [
  "serde_json",
  "thiserror",
  "tokio",
+ "tokio-tungstenite",
 ]
 
 [[package]]
@@ -519,6 +535,12 @@ dependencies = [
  "cipher",
 ]
 
+[[package]]
+name = "data-encoding"
+version = "2.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d7a1e2f27636f116493b8b860f5546edb47c8d8f8ea73e1d2a20be88e28d1fea"
+
 [[package]]
 name = "deranged"
 version = "0.5.8"
@@ -2125,6 +2147,17 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "sha1"
+version = "0.10.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e3bf829a2d51ab4a5ddf1352d8470c140cadc8301b2ae1789db023f01cedd6ba"
+dependencies = [
+ "cfg-if",
+ "cpufeatures",
+ "digest",
+]
+
 [[package]]
 name = "sha2"
 version = "0.10.9"
@@ -2495,6 +2528,22 @@ dependencies = [
  "tokio",
 ]
 
+[[package]]
+name = "tokio-tungstenite"
+version = "0.26.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7a9daff607c6d2bf6c16fd681ccb7eecc83e4e2cdc1ca067ffaadfca5de7f084"
+dependencies = [
+ "futures-util",
+ "log",
+ "rustls",
+ "rustls-pki-types",
+ "tokio",
+ "tokio-rustls",
+ "tungstenite",
+ "webpki-roots 0.26.11",
+]
+
 [[package]]
 name = "tokio-util"
 version = "0.7.18"
@@ -2693,6 +2742,25 @@ version = "0.2.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e421abadd41a4225275504ea4d6566923418b7f05506fbc9c0fe86ba7396114b"
 
+[[package]]
+name = "tungstenite"
+version = "0.26.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4793cb5e56680ecbb1d843515b23b6de9a75eb04b66643e256a396d43be33c13"
+dependencies = [
+ "bytes",
+ "data-encoding",
+ "http",
+ "httparse",
+ "log",
+ "rand 0.9.2",
+ "rustls",
+ "rustls-pki-types",
+ "sha1",
+ "thiserror",
+ "utf-8",
+]
+
 [[package]]
 name = "typenum"
 version = "1.19.0"
@@ -2772,6 +2840,12 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "utf-8"
+version = "0.7.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09cc8ee72d2a9becf2f2febe0205bbed8fc6615b7cb429ad062dc7b7ddd036a9"
+
 [[package]]
 name = "utf8_iter"
 version = "1.0.4"
diff --git a/Cargo.toml b/Cargo.toml
index beb18c3..d5a4d81 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,6 +11,7 @@ members = [
     "crates/crank-adapter-rest",
     "crates/crank-adapter-graphql",
     "crates/crank-adapter-grpc",
+    "crates/crank-adapter-websocket",
 ]
 resolver = "3"
 
@@ -46,4 +47,5 @@ tonic-build = "0.14"
 tonic-prost-build = "0.14"
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["env-filter", "fmt"] }
+tokio-tungstenite = { version = "0.26", features = ["rustls-tls-webpki-roots"] }
 uuid = { version = "1", features = ["serde", "v7"] }
diff --git a/TASKS.md b/TASKS.md
index 35b5bb0..7d0827b 100644
--- a/TASKS.md
+++ b/TASKS.md
@@ -2,25 +2,19 @@
 
 ## Current
 
-### `feat/streaming-e2e`
+### `feat/websocket-upstream-adapter`
 
 Status: completed
 
 DoD:
-- local fixture stack includes:
-  - REST SSE server
-  - gRPC server-streaming server
-  - WebSocket event server
-- Playwright covers:
-  - REST window flow
-  - gRPC streaming flow
-  - session tool flow
-  - async job flow
-- CI runs streaming e2e against the local fixture stack
+- bounded WebSocket window execution is supported
+- WebSocket protocol is exposed through capability APIs
+- session mode can seed from WebSocket window collection
+- runtime and adapter tests cover WebSocket collection and reconnects
 
 ## Next
 
-- `feat/websocket-upstream-adapter`
+- `feat/soap-architecture-and-core-model`
 
 ## Backlog
 
diff --git a/apps/admin-api/src/error.rs b/apps/admin-api/src/error.rs
index b0fe3f2..28b241b 100644
--- a/apps/admin-api/src/error.rs
+++ b/apps/admin-api/src/error.rs
@@ -238,6 +238,7 @@ fn runtime_test_failure_code(error: &RuntimeError) -> &'static str {
         RuntimeError::GraphqlAdapter(_) => "runtime_graphql_error",
         RuntimeError::GrpcAdapter(_) => "runtime_grpc_error",
         RuntimeError::RestAdapter(_) => "runtime_rest_error",
+        RuntimeError::WebsocketAdapter(_) => "runtime_websocket_error",
         RuntimeError::UnsupportedProtocol { .. } => "runtime_protocol_error",
         RuntimeError::InvalidPreparedRequest { .. } => "runtime_request_error",
         RuntimeError::MissingStreamingConfig { .. } => "runtime_streaming_config_error",
diff --git a/apps/admin-api/src/service.rs b/apps/admin-api/src/service.rs
index afaeab3..dab277a 100644
--- a/apps/admin-api/src/service.rs
+++ b/apps/admin-api/src/service.rs
@@ -1347,10 +1347,15 @@ impl AdminService {
     }
 
     pub async fn list_protocol_capabilities(&self) -> Vec<ProtocolCapabilityView> {
-        [Protocol::Rest, Protocol::Graphql, Protocol::Grpc]
-            .into_iter()
-            .map(protocol_capability_view)
-            .collect()
+        [
+            Protocol::Rest,
+            Protocol::Graphql,
+            Protocol::Grpc,
+            Protocol::Websocket,
+        ]
+        .into_iter()
+        .map(protocol_capability_view)
+        .collect()
     }
 
     #[instrument(skip(self))]
@@ -3601,6 +3606,7 @@ fn validate_protocol_target(protocol: Protocol, target: &Target) -> Result<(), A
         (Protocol::Rest, Target::Rest(_))
             | (Protocol::Graphql, Target::Graphql(_))
             | (Protocol::Grpc, Target::Grpc(_))
+            | (Protocol::Websocket, Target::Websocket(_))
     );
 
     if is_match {
@@ -3827,6 +3833,7 @@ fn demo_grpc_operation_payload() -> OperationPayload {
             headers: BTreeMap::new(),
             protocol_options: Some(crank_core::ProtocolOptions {
                 grpc: Some(crank_core::GrpcProtocolOptions { use_tls: false }),
+                websocket: None,
             }),
             streaming: None,
         },
@@ -4007,6 +4014,7 @@ fn runtime_error_code(error: &RuntimeError) -> &'static str {
         RuntimeError::GraphqlAdapter(_) => "graphql_error",
         RuntimeError::GrpcAdapter(_) => "grpc_error",
         RuntimeError::RestAdapter(_) => "rest_error",
+        RuntimeError::WebsocketAdapter(_) => "websocket_error",
         RuntimeError::UnsupportedProtocol { .. } => "unsupported_protocol",
         RuntimeError::MissingStreamingConfig { .. } => "streaming_config_error",
         RuntimeError::UnsupportedExecutionMode { .. } => "streaming_mode_error",
@@ -4034,7 +4042,7 @@ fn protocol_capability_view(protocol: Protocol) -> ProtocolCapabilityView {
     .filter(|behavior| protocol.supports_transport_behavior(*behavior))
     .collect();
     let supports_upload_artifacts = match protocol {
-        Protocol::Rest | Protocol::Graphql => Vec::new(),
+        Protocol::Rest | Protocol::Graphql | Protocol::Websocket => Vec::new(),
         Protocol::Grpc => vec!["proto".to_owned(), "descriptor_set".to_owned()],
     };
 
diff --git a/apps/mcp-server/src/app.rs b/apps/mcp-server/src/app.rs
index b48c1cd..8488684 100644
--- a/apps/mcp-server/src/app.rs
+++ b/apps/mcp-server/src/app.rs
@@ -1725,6 +1725,7 @@ fn runtime_error_code(error: &RuntimeError) -> &'static str {
         RuntimeError::GraphqlAdapter(_) => "adapter_execution_error",
         RuntimeError::GrpcAdapter(_) => "adapter_execution_error",
         RuntimeError::RestAdapter(_) => "adapter_execution_error",
+        RuntimeError::WebsocketAdapter(_) => "adapter_execution_error",
         RuntimeError::UnsupportedProtocol { .. } => "unsupported_protocol",
         RuntimeError::MissingStreamingConfig { .. } => "streaming_config_error",
         RuntimeError::UnsupportedExecutionMode { .. } => "streaming_mode_error",
diff --git a/apps/ui/html/workspace-setup.html b/apps/ui/html/workspace-setup.html
index 97b3eb1..2782632 100644
--- a/apps/ui/html/workspace-setup.html
+++ b/apps/ui/html/workspace-setup.html
@@ -95,6 +95,7 @@
               <option value="rest" selected>REST</option>
               <option value="graphql">GraphQL</option>
               <option value="grpc">gRPC</option>
+              <option value="websocket">WebSocket</option>
             </select>
             <div class="form-hint" data-i18n="workspace_setup.protocol_hint">Pre-selected in the operation wizard.</div>
           </div>
diff --git a/apps/ui/index.html b/apps/ui/index.html
index fa03f88..8a04077 100644
--- a/apps/ui/index.html
+++ b/apps/ui/index.html
@@ -181,13 +181,13 @@
           <svg class="chevron" width="10" height="10"><use href="icons/general/chevron-down.svg#icon"/></svg>
         </button>
         <div class="dropdown-menu" x-show="openDropdown === 'protocol'" x-transition>
-          <template x-for="p in ['rest','graphql','grpc']" :key="p">
+          <template x-for="p in ['rest','graphql','grpc','websocket']" :key="p">
             <button
               class="dropdown-item"
               :class="{ selected: filterProtocol === p }"
               @click="setProtocol(p)"
             >
-              <span x-text="p === 'rest' ? 'REST' : p === 'graphql' ? 'GraphQL' : 'gRPC'"></span>
+              <span x-text="p === 'rest' ? 'REST' : p === 'graphql' ? 'GraphQL' : p === 'grpc' ? 'gRPC' : 'WebSocket'"></span>
               <svg class="check" width="12" height="12"><use href="icons/general/check.svg#icon"/></svg>
             </button>
           </template>
diff --git a/apps/ui/js/agents.js b/apps/ui/js/agents.js
index 53fa723..a4b3609 100644
--- a/apps/ui/js/agents.js
+++ b/apps/ui/js/agents.js
@@ -416,12 +416,14 @@ document.addEventListener('alpine:init', function() {
       protocolBadge(operation) {
         if (operation.protocol === 'rest') return 'badge badge-rest';
         if (operation.protocol === 'graphql') return 'badge badge-graphql';
+        if (operation.protocol === 'websocket') return 'badge badge-rest';
         return 'badge badge-grpc';
       },
 
       protocolLabel(operation) {
         if (operation.protocol === 'rest') return 'REST';
         if (operation.protocol === 'graphql') return 'GQL';
+        if (operation.protocol === 'websocket') return 'WS';
         return 'gRPC';
       },
 
diff --git a/apps/ui/js/catalog.js b/apps/ui/js/catalog.js
index 525b0f1..f12028f 100644
--- a/apps/ui/js/catalog.js
+++ b/apps/ui/js/catalog.js
@@ -399,6 +399,7 @@ document.addEventListener('alpine:init', function() {
           return operation.method ? ('REST · ' + operation.method) : 'REST';
         }
         if (operation.protocol === 'graphql') return 'GraphQL';
+        if (operation.protocol === 'websocket') return 'WebSocket';
         return 'gRPC';
       },
 
diff --git a/apps/ui/js/i18n.js b/apps/ui/js/i18n.js
index 6f8cf8b..3780b4a 100644
--- a/apps/ui/js/i18n.js
+++ b/apps/ui/js/i18n.js
@@ -410,6 +410,7 @@ var TRANSLATIONS = {
     'workspace_setup.custom_protocol.rest': 'REST',
     'workspace_setup.custom_protocol.graphql': 'GraphQL',
     'workspace_setup.custom_protocol.grpc': 'gRPC',
+    'workspace_setup.custom_protocol.websocket': 'WebSocket',
 
     // Wizard
     'wizard.back_catalog': 'Operations',
@@ -444,6 +445,8 @@ var TRANSLATIONS = {
     'wizard.step1.graphql_tagline': 'Query and mutate a GraphQL schema. Supports queries and mutations over one fixed operation.',
     'wizard.step1.grpc_name': 'gRPC',
     'wizard.step1.grpc_tagline': 'High-performance binary RPC over HTTP/2. Ideal for low-latency internal services.',
+    'wizard.step1.websocket_name': 'WebSocket',
+    'wizard.step1.websocket_tagline': 'Stateful event streams and push-oriented integrations normalized into bounded MCP streaming tools.',
     'wizard.step1.query': 'Query',
     'wizard.step1.mutation': 'Mutation',
     'wizard.step1.unary': 'Unary',
@@ -1192,6 +1195,7 @@ var TRANSLATIONS = {
     'workspace_setup.custom_protocol.rest': 'REST',
     'workspace_setup.custom_protocol.graphql': 'GraphQL',
     'workspace_setup.custom_protocol.grpc': 'gRPC',
+    'workspace_setup.custom_protocol.websocket': 'WebSocket',
 
     // Wizard
     'wizard.back_catalog': 'Операции',
@@ -1226,6 +1230,8 @@ var TRANSLATIONS = {
     'wizard.step1.graphql_tagline': 'Запросы и мутации к GraphQL-схеме. Поддерживаются query и mutation для одной фиксированной операции.',
     'wizard.step1.grpc_name': 'gRPC',
     'wizard.step1.grpc_tagline': 'Высокопроизводительный бинарный RPC поверх HTTP/2. Подходит для низколатентных внутренних сервисов.',
+    'wizard.step1.websocket_name': 'WebSocket',
+    'wizard.step1.websocket_tagline': 'Состояние соединения, event streams и push-oriented интеграции, нормализованные в bounded MCP streaming tools.',
     'wizard.step1.query': 'Запрос',
     'wizard.step1.mutation': 'Мутация',
     'wizard.step1.unary': 'Unary',
diff --git a/apps/ui/js/usage.js b/apps/ui/js/usage.js
index 99f16e0..dcf94c0 100644
--- a/apps/ui/js/usage.js
+++ b/apps/ui/js/usage.js
@@ -58,6 +58,9 @@ document.addEventListener('DOMContentLoaded', function () {
     if (protocol === 'grpc' || protocol === 'Grpc') {
       return 'var(--accent)';
     }
+    if (protocol === 'websocket' || protocol === 'Websocket') {
+      return 'var(--teal)';
+    }
     return 'var(--blue)';
   }
 
@@ -68,6 +71,9 @@ document.addEventListener('DOMContentLoaded', function () {
     if (protocol === 'grpc' || protocol === 'Grpc') {
       return 'gRPC';
     }
+    if (protocol === 'websocket' || protocol === 'Websocket') {
+      return 'WebSocket';
+    }
     return 'REST';
   }
 
diff --git a/apps/ui/js/wizard.js b/apps/ui/js/wizard.js
index 74a80e1..a66e79f 100644
--- a/apps/ui/js/wizard.js
+++ b/apps/ui/js/wizard.js
@@ -1,6 +1,6 @@
 var currentStep = 1;
 var TOTAL_STEPS = 5;
-var wizardProtocol = 'rest'; // 'rest' | 'graphql' | 'grpc'
+var wizardProtocol = 'rest'; // 'rest' | 'graphql' | 'grpc' | 'websocket'
 var wizardMode   = 'create'; // 'create' | 'edit'
 var wizardEditId = null;
 var wizardWorkspaceId = null;
@@ -32,6 +32,10 @@ function defaultProtocolCapabilities() {
       supports_execution_modes: ['unary', 'window', 'session', 'async_job'],
       supports_transport_behaviors: ['request_response', 'server_stream'],
     },
+    websocket: {
+      supports_execution_modes: ['window', 'session', 'async_job'],
+      supports_transport_behaviors: ['server_stream', 'stateful_session', 'deferred_result'],
+    },
   };
 }
 
diff --git a/crates/crank-adapter-websocket/Cargo.toml b/crates/crank-adapter-websocket/Cargo.toml
new file mode 100644
index 0000000..28164dd
--- /dev/null
+++ b/crates/crank-adapter-websocket/Cargo.toml
@@ -0,0 +1,19 @@
+[package]
+name = "crank-adapter-websocket"
+edition.workspace = true
+license.workspace = true
+rust-version.workspace = true
+version.workspace = true
+
+[dependencies]
+crank-core = { path = "../crank-core" }
+futures-util = "0.3"
+reqwest.workspace = true
+serde.workspace = true
+serde_json.workspace = true
+thiserror.workspace = true
+tokio = { workspace = true, features = ["net", "time"] }
+tokio-tungstenite.workspace = true
+
+[dev-dependencies]
+tokio = { workspace = true, features = ["macros", "net", "rt-multi-thread", "time"] }
diff --git a/crates/crank-adapter-websocket/src/client.rs b/crates/crank-adapter-websocket/src/client.rs
new file mode 100644
index 0000000..a67486e
--- /dev/null
+++ b/crates/crank-adapter-websocket/src/client.rs
@@ -0,0 +1,442 @@
+use std::{collections::BTreeMap, time::Duration};
+
+use crank_core::WebsocketTarget;
+use futures_util::{SinkExt, StreamExt};
+use reqwest::header::{HeaderMap, HeaderName, HeaderValue};
+use serde_json::Value;
+use tokio::time::{Instant, sleep};
+use tokio_tungstenite::{
+    MaybeTlsStream, WebSocketStream, connect_async,
+    tungstenite::{
+        Error as TungsteniteError, Message,
+        client::IntoClientRequest,
+        protocol::{CloseFrame, frame::coding::CloseCode},
+    },
+};
+
+use crate::{
+    HeartbeatPolicy, ReconnectPolicy, WebsocketAdapterError, WebsocketWindowRequest,
+    WebsocketWindowResponse,
+};
+
+#[derive(Clone, Debug)]
+pub struct WebsocketAdapter;
+
+impl Default for WebsocketAdapter {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl WebsocketAdapter {
+    pub fn new() -> Self {
+        Self
+    }
+
+    pub async fn execute_window(
+        &self,
+        target: &WebsocketTarget,
+        request: &WebsocketWindowRequest,
+    ) -> Result<WebsocketWindowResponse, WebsocketAdapterError> {
+        let started_at = Instant::now();
+        let deadline = started_at + Duration::from_millis(request.window_duration_ms);
+        let heartbeat = request
+            .heartbeat_interval_ms
+            .map(Duration::from_millis)
+            .map(|interval| crate::HeartbeatPolicy { interval });
+        let reconnect = ReconnectPolicy {
+            max_attempts: request.reconnect_max_attempts,
+            backoff: Duration::from_millis(request.reconnect_backoff_ms),
+        };
+        let mut attempts = 0_u32;
+        let mut items = Vec::new();
+        let mut connected_headers = BTreeMap::new();
+
+        loop {
+            let (mut stream, headers) = connect_websocket(target, request).await?;
+            if connected_headers.is_empty() {
+                connected_headers = headers;
+            }
+
+            send_subscribe_message(&mut stream, target).await?;
+
+            let completed = collect_window(
+                &mut stream,
+                request.max_items,
+                deadline,
+                heartbeat.as_ref(),
+                &mut items,
+            )
+            .await?;
+
+            if completed {
+                send_unsubscribe_message(&mut stream, target).await?;
+                return Ok(WebsocketWindowResponse {
+                    status_code: 101,
+                    headers: connected_headers,
+                    body: serde_json::json!({
+                        "items": items,
+                        "done": true,
+                    }),
+                });
+            }
+
+            if attempts >= reconnect.max_attempts {
+                return Err(WebsocketAdapterError::ReconnectExhausted);
+            }
+
+            attempts = attempts.saturating_add(1);
+            reconnect_if_needed(&reconnect, attempts).await;
+        }
+    }
+}
+
+type WsStream = WebSocketStream<MaybeTlsStream<tokio::net::TcpStream>>;
+
+pub async fn connect_websocket(
+    target: &WebsocketTarget,
+    request: &WebsocketWindowRequest,
+) -> Result<(WsStream, BTreeMap<String, String>), WebsocketAdapterError> {
+    let mut client_request = target.url.as_str().into_client_request().map_err(|_| {
+        WebsocketAdapterError::InvalidUrl {
+            url: target.url.clone(),
+        }
+    })?;
+    let headers = build_headers(target, request)?;
+    for (name, value) in &headers {
+        client_request
+            .headers_mut()
+            .insert(name.clone(), value.clone());
+    }
+
+    if !target.subprotocols.is_empty() {
+        let value = target.subprotocols.join(", ");
+        let header_value = HeaderValue::from_str(&value)
+            .map_err(|_| WebsocketAdapterError::InvalidSubprotocol { value })?;
+        client_request
+            .headers_mut()
+            .insert("Sec-WebSocket-Protocol", header_value);
+    }
+
+    let (stream, response) = connect_async(client_request).await?;
+    let response_headers = response
+        .headers()
+        .iter()
+        .filter_map(|(name, value)| {
+            value
+                .to_str()
+                .ok()
+                .map(|value| (name.as_str().to_owned(), value.to_owned()))
+        })
+        .collect();
+    Ok((stream, response_headers))
+}
+
+pub async fn send_subscribe_message(
+    stream: &mut WsStream,
+    target: &WebsocketTarget,
+) -> Result<(), WebsocketAdapterError> {
+    let Some(payload) = target.subscribe_message_template.as_ref() else {
+        return Ok(());
+    };
+
+    let message = serde_json::to_string(payload)
+        .map_err(|_| WebsocketAdapterError::InvalidSubscribePayload)?;
+    stream.send(Message::Text(message.into())).await?;
+    Ok(())
+}
+
+pub async fn send_unsubscribe_message(
+    stream: &mut WsStream,
+    target: &WebsocketTarget,
+) -> Result<(), WebsocketAdapterError> {
+    let Some(payload) = target.unsubscribe_message_template.as_ref() else {
+        let _ = stream
+            .close(Some(CloseFrame {
+                code: CloseCode::Normal,
+                reason: "completed".into(),
+            }))
+            .await;
+        return Ok(());
+    };
+
+    let message = serde_json::to_string(payload)
+        .map_err(|_| WebsocketAdapterError::InvalidUnsubscribePayload)?;
+    if let Err(error) = stream.send(Message::Text(message.into())).await {
+        if !matches!(
+            error,
+            TungsteniteError::ConnectionClosed
+                | TungsteniteError::AlreadyClosed
+                | TungsteniteError::Protocol(
+                    tokio_tungstenite::tungstenite::error::ProtocolError::SendAfterClosing
+                )
+        ) {
+            return Err(error.into());
+        }
+    }
+    let _ = stream
+        .close(Some(CloseFrame {
+            code: CloseCode::Normal,
+            reason: "completed".into(),
+        }))
+        .await;
+    Ok(())
+}
+
+async fn collect_window(
+    stream: &mut WsStream,
+    max_items: Option<u32>,
+    deadline: Instant,
+    heartbeat: Option<&HeartbeatPolicy>,
+    items: &mut Vec<Value>,
+) -> Result<bool, WebsocketAdapterError> {
+    let mut heartbeat_deadline = heartbeat.map(|policy| Instant::now() + policy.interval);
+
+    loop {
+        if Instant::now() >= deadline {
+            return Ok(!items.is_empty());
+        }
+
+        let now = Instant::now();
+        let next_tick = heartbeat_deadline.unwrap_or(deadline);
+        let sleep_until = std::cmp::min(next_tick, deadline);
+        let wait = sleep_until.saturating_duration_since(now);
+        let timer = sleep(wait);
+        tokio::pin!(timer);
+
+        tokio::select! {
+            _ = &mut timer => {
+                if heartbeat_deadline.is_some_and(|value| value <= Instant::now()) {
+                    heartbeat_tick(stream).await?;
+                    heartbeat_deadline = heartbeat.map(|policy| Instant::now() + policy.interval);
+                    continue;
+                }
+
+                return Ok(!items.is_empty());
+            }
+            frame = read_next_frame(stream) => {
+                match frame? {
+                    Some(value) => {
+                        items.push(value);
+                        if max_items.is_some_and(|limit| items.len() as u32 >= limit) {
+                            return Ok(true);
+                        }
+                    }
+                    None => return Ok(!items.is_empty()),
+                }
+                heartbeat_deadline = heartbeat.map(|policy| Instant::now() + policy.interval);
+            }
+        }
+    }
+}
+
+pub async fn read_next_frame(
+    stream: &mut WsStream,
+) -> Result<Option<Value>, WebsocketAdapterError> {
+    loop {
+        let Some(frame) = stream.next().await else {
+            return Ok(None);
+        };
+
+        match frame? {
+            Message::Text(text) => return Ok(Some(decode_text_frame(text.as_ref())?)),
+            Message::Binary(_) => return Err(WebsocketAdapterError::InvalidFramePayload),
+            Message::Ping(payload) => {
+                stream.send(Message::Pong(payload)).await?;
+            }
+            Message::Pong(_) => {}
+            Message::Frame(_) => {}
+            Message::Close(_) => return Ok(None),
+        }
+    }
+}
+
+pub fn decode_text_frame(text: &str) -> Result<Value, WebsocketAdapterError> {
+    serde_json::from_str(text).or_else(|_| Ok(Value::String(text.to_owned())))
+}
+
+pub async fn heartbeat_tick(stream: &mut WsStream) -> Result<(), WebsocketAdapterError> {
+    stream.send(Message::Ping(Vec::new().into())).await?;
+    Ok(())
+}
+
+pub async fn reconnect_if_needed(policy: &ReconnectPolicy, attempts: u32) {
+    if attempts == 0 || policy.backoff.is_zero() {
+        return;
+    }
+
+    sleep(policy.backoff).await;
+}
+
+fn build_headers(
+    target: &WebsocketTarget,
+    request: &WebsocketWindowRequest,
+) -> Result<HeaderMap, WebsocketAdapterError> {
+    let mut headers = HeaderMap::new();
+
+    for (name, value) in target.static_headers.iter().chain(request.headers.iter()) {
+        let header_name = HeaderName::try_from(name.as_str()).map_err(|_| {
+            WebsocketAdapterError::InvalidHeaderName {
+                header: name.clone(),
+            }
+        })?;
+        let header_value = HeaderValue::try_from(value.as_str()).map_err(|_| {
+            WebsocketAdapterError::InvalidHeaderValue {
+                header: name.clone(),
+            }
+        })?;
+        headers.insert(header_name, header_value);
+    }
+
+    Ok(headers)
+}
+
+#[cfg(test)]
+mod tests {
+    use std::{collections::BTreeMap, sync::Arc};
+
+    use futures_util::{SinkExt, StreamExt};
+    use serde_json::{Value, json};
+    use tokio::{net::TcpListener, sync::Mutex};
+    use tokio_tungstenite::{
+        accept_hdr_async,
+        tungstenite::handshake::server::{Request, Response},
+    };
+
+    use crate::{WebsocketAdapter, WebsocketWindowRequest};
+    use crank_core::WebsocketTarget;
+
+    #[tokio::test]
+    async fn collects_window_messages_and_sends_subscribe_payload() {
+        let received = Arc::new(Mutex::new(Vec::new()));
+        let target_url = spawn_server(received.clone(), false).await;
+        let adapter = WebsocketAdapter::new();
+        let target = WebsocketTarget {
+            url: target_url,
+            subprotocols: vec!["events.v1".to_owned()],
+            subscribe_message_template: Some(json!({"type":"subscribe","topic":"metrics"})),
+            unsubscribe_message_template: Some(json!({"type":"unsubscribe"})),
+            static_headers: BTreeMap::from([("x-test-env".to_owned(), "ci".to_owned())]),
+        };
+        let response = adapter
+            .execute_window(
+                &target,
+                &WebsocketWindowRequest {
+                    headers: BTreeMap::new(),
+                    window_duration_ms: 1_000,
+                    max_items: Some(3),
+                    heartbeat_interval_ms: None,
+                    reconnect_max_attempts: 0,
+                    reconnect_backoff_ms: 0,
+                },
+            )
+            .await
+            .unwrap();
+
+        assert_eq!(response.status_code, 101);
+        assert_eq!(response.body["items"].as_array().unwrap().len(), 3);
+        assert_eq!(response.body["items"][0]["seq"], 1);
+
+        let received = received.lock().await.clone();
+        assert!(
+            received
+                .iter()
+                .any(|value| value == &json!({"type":"subscribe","topic":"metrics"}))
+        );
+    }
+
+    #[tokio::test]
+    async fn reconnects_when_socket_closes_early() {
+        let received = Arc::new(Mutex::new(Vec::new()));
+        let target_url = spawn_server(received, true).await;
+        let adapter = WebsocketAdapter::new();
+        let target = WebsocketTarget {
+            url: target_url,
+            subprotocols: Vec::new(),
+            subscribe_message_template: None,
+            unsubscribe_message_template: None,
+            static_headers: BTreeMap::new(),
+        };
+        let response = adapter
+            .execute_window(
+                &target,
+                &WebsocketWindowRequest {
+                    headers: BTreeMap::new(),
+                    window_duration_ms: 1_000,
+                    max_items: Some(3),
+                    heartbeat_interval_ms: None,
+                    reconnect_max_attempts: 2,
+                    reconnect_backoff_ms: 10,
+                },
+            )
+            .await
+            .unwrap();
+
+        assert_eq!(response.body["items"].as_array().unwrap().len(), 3);
+        assert_eq!(response.body["items"][2]["seq"], 3);
+    }
+
+    async fn spawn_server(received: Arc<Mutex<Vec<Value>>>, close_early: bool) -> String {
+        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+        let addr = listener.local_addr().unwrap();
+
+        tokio::spawn(async move {
+            let mut accepted = 0_u32;
+            loop {
+                let (stream, _) = listener.accept().await.unwrap();
+                let received = received.clone();
+                accepted = accepted.saturating_add(1);
+                tokio::spawn(async move {
+                    let websocket =
+                        accept_hdr_async(stream, |request: &Request, mut response: Response| {
+                            if let Some(value) = request.headers().get("x-test-env") {
+                                assert_eq!(value, "ci");
+                            }
+                            if let Some(value) = request.headers().get("sec-websocket-protocol") {
+                                response
+                                    .headers_mut()
+                                    .insert("sec-websocket-protocol", value.clone());
+                            }
+                            Ok(response)
+                        })
+                        .await
+                        .unwrap();
+                    let (mut sink, mut source) = websocket.split();
+                    let mut sent = 0_u32;
+
+                    if !close_early {
+                        if let Some(message) = source.next().await {
+                            let message = message.unwrap();
+                            if let tokio_tungstenite::tungstenite::Message::Text(text) = message {
+                                if let Ok(value) = serde_json::from_str::<Value>(&text) {
+                                    received.lock().await.push(value);
+                                }
+                            }
+                        }
+                    }
+
+                    let payloads = if close_early && accepted == 1 {
+                        Vec::new()
+                    } else {
+                        vec![json!({"seq": 1}), json!({"seq": 2}), json!({"seq": 3})]
+                    };
+
+                    for payload in payloads {
+                        sink.send(tokio_tungstenite::tungstenite::Message::Text(
+                            payload.to_string().into(),
+                        ))
+                        .await
+                        .unwrap();
+                        sent += 1;
+                    }
+
+                    if sent < 3 {
+                        let _ = sink.close().await;
+                    }
+                });
+            }
+        });
+
+        format!("ws://{}", addr)
+    }
+}
diff --git a/crates/crank-adapter-websocket/src/error.rs b/crates/crank-adapter-websocket/src/error.rs
new file mode 100644
index 0000000..17c8359
--- /dev/null
+++ b/crates/crank-adapter-websocket/src/error.rs
@@ -0,0 +1,30 @@
+use serde_json::Value;
+use thiserror::Error;
+
+#[derive(Debug, Error)]
+pub enum WebsocketAdapterError {
+    #[error("invalid websocket url: {url}")]
+    InvalidUrl { url: String },
+    #[error("invalid websocket header name {header}")]
+    InvalidHeaderName { header: String },
+    #[error("invalid websocket header value for {header}")]
+    InvalidHeaderValue { header: String },
+    #[error("invalid websocket subprotocol {value}")]
+    InvalidSubprotocol { value: String },
+    #[error("websocket connect failed")]
+    Connect(#[from] tokio_tungstenite::tungstenite::Error),
+    #[error("websocket window expired before collecting any items")]
+    WindowExpired,
+    #[error("websocket stream produced malformed frame payload")]
+    InvalidFramePayload,
+    #[error("websocket endpoint returned close frame before collection completed")]
+    ClosedEarly,
+    #[error("websocket reconnect policy exhausted")]
+    ReconnectExhausted,
+    #[error("websocket upstream returned invalid subscribe payload")]
+    InvalidSubscribePayload,
+    #[error("websocket upstream returned invalid unsubscribe payload")]
+    InvalidUnsubscribePayload,
+    #[error("websocket upstream status {status}")]
+    UnexpectedStatus { status: u16, body: Value },
+}
diff --git a/crates/crank-adapter-websocket/src/lib.rs b/crates/crank-adapter-websocket/src/lib.rs
new file mode 100644
index 0000000..f7f958d
--- /dev/null
+++ b/crates/crank-adapter-websocket/src/lib.rs
@@ -0,0 +1,35 @@
+mod client;
+mod error;
+mod session;
+
+use std::collections::BTreeMap;
+
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+
+pub use client::WebsocketAdapter;
+pub use error::WebsocketAdapterError;
+pub use session::{HeartbeatPolicy, ReconnectPolicy};
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Default)]
+pub struct WebsocketWindowRequest {
+    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
+    pub headers: BTreeMap<String, String>,
+    pub window_duration_ms: u64,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub max_items: Option<u32>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub heartbeat_interval_ms: Option<u64>,
+    #[serde(default)]
+    pub reconnect_max_attempts: u32,
+    #[serde(default)]
+    pub reconnect_backoff_ms: u64,
+}
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+pub struct WebsocketWindowResponse {
+    pub status_code: u16,
+    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
+    pub headers: BTreeMap<String, String>,
+    pub body: Value,
+}
diff --git a/crates/crank-adapter-websocket/src/session.rs b/crates/crank-adapter-websocket/src/session.rs
new file mode 100644
index 0000000..3c7b23c
--- /dev/null
+++ b/crates/crank-adapter-websocket/src/session.rs
@@ -0,0 +1,21 @@
+use std::time::Duration;
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct ReconnectPolicy {
+    pub max_attempts: u32,
+    pub backoff: Duration,
+}
+
+impl Default for ReconnectPolicy {
+    fn default() -> Self {
+        Self {
+            max_attempts: 0,
+            backoff: Duration::from_millis(0),
+        }
+    }
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct HeartbeatPolicy {
+    pub interval: Duration,
+}
diff --git a/crates/crank-core/src/lib.rs b/crates/crank-core/src/lib.rs
index 1006a79..f2110c4 100644
--- a/crates/crank-core/src/lib.rs
+++ b/crates/crank-core/src/lib.rs
@@ -30,7 +30,8 @@ pub use observability::{
 pub use operation::{
     ConfigExport, ExecutionConfig, GeneratedDraft, GeneratedDraftStatus, GraphqlTarget,
     GrpcProtocolOptions, GrpcTarget, Operation, OperationStatus, ProtocolOptions, RestTarget,
-    RetryPolicy, Samples, Target, ToolDescription, ToolExample,
+    RetryPolicy, Samples, Target, ToolDescription, ToolExample, WebsocketProtocolOptions,
+    WebsocketTarget,
 };
 pub use protocol::{AuthKind, ExportMode, GraphqlOperationType, HttpMethod, Protocol};
 pub use secret::{Secret, SecretKind, SecretStatus, SecretVersion};
diff --git a/crates/crank-core/src/operation.rs b/crates/crank-core/src/operation.rs
index 709e673..b4ab07c 100644
--- a/crates/crank-core/src/operation.rs
+++ b/crates/crank-core/src/operation.rs
@@ -50,12 +50,26 @@ pub struct GrpcTarget {
     pub descriptor_set_b64: String,
 }
 
-#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+pub struct WebsocketTarget {
+    pub url: String,
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub subprotocols: Vec<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub subscribe_message_template: Option<Value>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub unsubscribe_message_template: Option<Value>,
+    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
+    pub static_headers: BTreeMap<String, String>,
+}
+
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
 #[serde(tag = "kind", rename_all = "snake_case")]
 pub enum Target {
     Rest(RestTarget),
     Graphql(GraphqlTarget),
     Grpc(GrpcTarget),
+    Websocket(WebsocketTarget),
 }
 
 #[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Default)]
@@ -68,10 +82,22 @@ pub struct GrpcProtocolOptions {
     pub use_tls: bool,
 }
 
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Default)]
+pub struct WebsocketProtocolOptions {
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub heartbeat_interval_ms: Option<u64>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub reconnect_max_attempts: Option<u32>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub reconnect_backoff_ms: Option<u64>,
+}
+
 #[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Default)]
 pub struct ProtocolOptions {
     #[serde(skip_serializing_if = "Option::is_none")]
     pub grpc: Option<GrpcProtocolOptions>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub websocket: Option<WebsocketProtocolOptions>,
 }
 
 #[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
@@ -209,6 +235,7 @@ mod tests {
         operation::{
             ConfigExport, ExecutionConfig, GraphqlTarget, Operation, OperationStatus,
             ProtocolOptions, RestTarget, Samples, Target, ToolDescription, ToolExample,
+            WebsocketProtocolOptions, WebsocketTarget,
         },
         protocol::{AuthKind, ExportMode, GraphqlOperationType, HttpMethod, Protocol},
     };
@@ -244,6 +271,23 @@ mod tests {
         assert_eq!(value["operation_type"], "mutation");
     }
 
+    #[test]
+    fn websocket_target_serializes_templates() {
+        let target = Target::Websocket(WebsocketTarget {
+            url: "wss://events.example.com/stream".to_owned(),
+            subprotocols: vec!["graphql-transport-ws".to_owned()],
+            subscribe_message_template: Some(json!({ "type": "subscribe" })),
+            unsubscribe_message_template: Some(json!({ "type": "unsubscribe" })),
+            static_headers: BTreeMap::from([("x-env".to_owned(), "test".to_owned())]),
+        });
+
+        let value = serde_json::to_value(target).unwrap();
+
+        assert_eq!(value["kind"], "websocket");
+        assert_eq!(value["subprotocols"][0], "graphql-transport-ws");
+        assert_eq!(value["subscribe_message_template"]["type"], "subscribe");
+    }
+
     #[test]
     fn operation_exposes_local_domain_helpers() {
         let operation = Operation {
@@ -269,7 +313,14 @@ mod tests {
                 retry_policy: None,
                 auth_profile_ref: Some(AuthProfileId::new("auth_01")),
                 headers: BTreeMap::new(),
-                protocol_options: Some(ProtocolOptions::default()),
+                protocol_options: Some(ProtocolOptions {
+                    grpc: None,
+                    websocket: Some(WebsocketProtocolOptions {
+                        heartbeat_interval_ms: Some(5_000),
+                        reconnect_max_attempts: Some(3),
+                        reconnect_backoff_ms: Some(250),
+                    }),
+                }),
                 streaming: None,
             },
             tool_description: ToolDescription {
diff --git a/crates/crank-core/src/protocol.rs b/crates/crank-core/src/protocol.rs
index 1f59eed..37fed0a 100644
--- a/crates/crank-core/src/protocol.rs
+++ b/crates/crank-core/src/protocol.rs
@@ -8,6 +8,7 @@ pub enum Protocol {
     Rest,
     Graphql,
     Grpc,
+    Websocket,
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
@@ -49,6 +50,7 @@ impl Protocol {
             Self::Rest => true,
             Self::Graphql => matches!(mode, ExecutionMode::Unary),
             Self::Grpc => true,
+            Self::Websocket => !matches!(mode, ExecutionMode::Unary),
         }
     }
 
@@ -57,6 +59,7 @@ impl Protocol {
             Self::Rest => true,
             Self::Graphql => matches!(behavior, TransportBehavior::RequestResponse),
             Self::Grpc => !matches!(behavior, TransportBehavior::DeferredResult),
+            Self::Websocket => !matches!(behavior, TransportBehavior::RequestResponse),
         }
     }
 }
@@ -79,4 +82,20 @@ mod tests {
         assert!(Protocol::Grpc.supports_execution_mode(ExecutionMode::Session));
         assert!(!Protocol::Grpc.supports_transport_behavior(TransportBehavior::DeferredResult));
     }
+
+    #[test]
+    fn websocket_requires_streaming_modes() {
+        assert!(!Protocol::Websocket.supports_execution_mode(ExecutionMode::Unary));
+        assert!(Protocol::Websocket.supports_execution_mode(ExecutionMode::Window));
+        assert!(Protocol::Websocket.supports_execution_mode(ExecutionMode::Session));
+        assert!(Protocol::Websocket.supports_execution_mode(ExecutionMode::AsyncJob));
+        assert!(
+            !Protocol::Websocket.supports_transport_behavior(TransportBehavior::RequestResponse)
+        );
+        assert!(Protocol::Websocket.supports_transport_behavior(TransportBehavior::ServerStream));
+        assert!(
+            Protocol::Websocket.supports_transport_behavior(TransportBehavior::StatefulSession)
+        );
+        assert!(Protocol::Websocket.supports_transport_behavior(TransportBehavior::DeferredResult));
+    }
 }
diff --git a/crates/crank-registry/src/postgres.rs b/crates/crank-registry/src/postgres.rs
index 00c21e3..fb3882c 100644
--- a/crates/crank-registry/src/postgres.rs
+++ b/crates/crank-registry/src/postgres.rs
@@ -3958,6 +3958,7 @@ fn target_summary(target: &Target) -> (String, String) {
             .to_owned(),
         ),
         Target::Grpc(grpc) => (grpc.server_addr.clone(), grpc.method.clone()),
+        Target::Websocket(websocket) => (websocket.url.clone(), "SUBSCRIBE".to_owned()),
     }
 }
 
diff --git a/crates/crank-runtime/Cargo.toml b/crates/crank-runtime/Cargo.toml
index c3b6334..7445076 100644
--- a/crates/crank-runtime/Cargo.toml
+++ b/crates/crank-runtime/Cargo.toml
@@ -9,6 +9,7 @@ version.workspace = true
 crank-adapter-graphql = { path = "../crank-adapter-graphql" }
 crank-adapter-grpc = { path = "../crank-adapter-grpc" }
 crank-adapter-rest = { path = "../crank-adapter-rest" }
+crank-adapter-websocket = { path = "../crank-adapter-websocket" }
 crank-core = { path = "../crank-core" }
 crank-mapping = { path = "../crank-mapping" }
 crank-schema = { path = "../crank-schema" }
@@ -21,3 +22,4 @@ axum.workspace = true
 crank-adapter-grpc = { path = "../crank-adapter-grpc", features = ["test-support"] }
 futures-util = "0.3"
 tokio.workspace = true
+tokio-tungstenite.workspace = true
diff --git a/crates/crank-runtime/src/error.rs b/crates/crank-runtime/src/error.rs
index dfb00c4..2f88134 100644
--- a/crates/crank-runtime/src/error.rs
+++ b/crates/crank-runtime/src/error.rs
@@ -1,6 +1,7 @@
 use crank_adapter_graphql::GraphqlAdapterError;
 use crank_adapter_grpc::GrpcAdapterError;
 use crank_adapter_rest::RestAdapterError;
+use crank_adapter_websocket::WebsocketAdapterError;
 use crank_core::{ExecutionMode, Protocol};
 use crank_mapping::MappingError;
 use crank_schema::SchemaError;
@@ -18,6 +19,8 @@ pub enum RuntimeError {
     GrpcAdapter(#[from] GrpcAdapterError),
     #[error(transparent)]
     RestAdapter(#[from] RestAdapterError),
+    #[error(transparent)]
+    WebsocketAdapter(#[from] WebsocketAdapterError),
     #[error("protocol {protocol:?} is not supported by runtime")]
     UnsupportedProtocol { protocol: Protocol },
     #[error("operation {operation_id} does not define streaming config")]
diff --git a/crates/crank-runtime/src/executor.rs b/crates/crank-runtime/src/executor.rs
index d73ba6f..3185ac8 100644
--- a/crates/crank-runtime/src/executor.rs
+++ b/crates/crank-runtime/src/executor.rs
@@ -3,6 +3,7 @@ use std::collections::BTreeMap;
 use crank_adapter_graphql::{GraphqlAdapter, GraphqlRequest};
 use crank_adapter_grpc::{GrpcAdapter, GrpcRequest, GrpcWindowRequest};
 use crank_adapter_rest::{RestAdapter, RestRequest, RestWindowRequest};
+use crank_adapter_websocket::{WebsocketAdapter, WebsocketWindowRequest};
 use crank_core::{ExecutionMode, Target, TransportBehavior};
 use serde_json::{Map, Value, json};
 
@@ -15,6 +16,7 @@ pub struct RuntimeExecutor {
     graphql_adapter: GraphqlAdapter,
     grpc_adapter: GrpcAdapter,
     rest_adapter: RestAdapter,
+    websocket_adapter: WebsocketAdapter,
 }
 
 impl Default for RuntimeExecutor {
@@ -29,6 +31,7 @@ impl RuntimeExecutor {
             graphql_adapter: GraphqlAdapter::new(),
             grpc_adapter: GrpcAdapter::new(),
             rest_adapter: RestAdapter::new(),
+            websocket_adapter: WebsocketAdapter::new(),
         }
     }
 
@@ -63,8 +66,10 @@ impl RuntimeExecutor {
         let adapter_response = if matches!(
             streaming.transport_behavior,
             TransportBehavior::ServerStream
-        ) && matches!(operation.target, Target::Rest(_) | Target::Grpc(_))
-        {
+        ) && matches!(
+            operation.target,
+            Target::Rest(_) | Target::Grpc(_) | Target::Websocket(_)
+        ) {
             self.execute_window_adapter(operation, prepared_request)
                 .await?
         } else {
@@ -200,6 +205,10 @@ impl RuntimeExecutor {
                     data: Value::Null,
                 })
             }
+            Target::Websocket(_) => Err(RuntimeError::UnsupportedExecutionMode {
+                operation_id: operation.operation_id.as_str().to_owned(),
+                mode: ExecutionMode::Unary,
+            }),
         }
     }
 
@@ -274,6 +283,46 @@ impl RuntimeExecutor {
                     data: Value::Null,
                 })
             }
+            Target::Websocket(target) => {
+                let Some(streaming) = operation.execution_config.streaming.as_ref() else {
+                    return Err(RuntimeError::MissingStreamingConfig {
+                        operation_id: operation.operation_id.as_str().to_owned(),
+                    });
+                };
+                let websocket_options = operation
+                    .execution_config
+                    .protocol_options
+                    .as_ref()
+                    .and_then(|options| options.websocket.as_ref());
+                let request = WebsocketWindowRequest {
+                    headers: merge_headers(
+                        &BTreeMap::new(),
+                        &operation.execution_config.headers,
+                        &prepared_request.headers,
+                    ),
+                    window_duration_ms: streaming.window_duration_ms.unwrap_or_default(),
+                    max_items: streaming.max_items.map(|value| value.saturating_add(1)),
+                    heartbeat_interval_ms: websocket_options
+                        .and_then(|options| options.heartbeat_interval_ms),
+                    reconnect_max_attempts: websocket_options
+                        .and_then(|options| options.reconnect_max_attempts)
+                        .unwrap_or_default(),
+                    reconnect_backoff_ms: websocket_options
+                        .and_then(|options| options.reconnect_backoff_ms)
+                        .unwrap_or_default(),
+                };
+                let response = self
+                    .websocket_adapter
+                    .execute_window(target, &request)
+                    .await?;
+
+                Ok(AdapterResponse {
+                    status_code: response.status_code,
+                    headers: response.headers,
+                    body: response.body,
+                    data: Value::Null,
+                })
+            }
             _ => self.execute_adapter(operation, prepared_request).await,
         }
     }
@@ -391,14 +440,16 @@ mod tests {
     use crank_core::{
         AggregationMode, DescriptorId, ExecutionConfig, ExecutionMode, GeneratedDraft,
         GeneratedDraftStatus, GraphqlOperationType, GraphqlTarget, GrpcTarget, HttpMethod,
-        Operation, OperationId, OperationStatus, Protocol, RestTarget, Samples, StreamingConfig,
-        Target, ToolDescription, ToolExample, ToolFamilyConfig, TransportBehavior,
+        Operation, OperationId, OperationStatus, Protocol, ProtocolOptions, RestTarget, Samples,
+        StreamingConfig, Target, ToolDescription, ToolExample, ToolFamilyConfig, TransportBehavior,
+        WebsocketProtocolOptions, WebsocketTarget,
     };
     use crank_mapping::{MappingRule, MappingSet};
     use crank_schema::{Schema, SchemaKind};
-    use futures_util::stream;
+    use futures_util::{SinkExt, StreamExt, stream};
     use serde_json::{Value, json};
     use tokio::net::TcpListener;
+    use tokio_tungstenite::accept_async;
 
     use crate::{RuntimeError, RuntimeExecutor, RuntimeOperation};
 
@@ -464,6 +515,26 @@ mod tests {
         assert!(!result.window_complete);
     }
 
+    #[tokio::test]
+    async fn executes_websocket_window_mode_end_to_end() {
+        let target_url = spawn_websocket_server().await;
+        let executor = RuntimeExecutor::new();
+        let operation =
+            test_websocket_window_operation(&target_url, AggregationMode::RawItems, Some(3));
+
+        let result = executor
+            .execute_window(&operation, &json!({}))
+            .await
+            .unwrap();
+
+        assert_eq!(result.items.len(), 3);
+        assert_eq!(result.items[0], json!({ "seq": 1, "value": 101 }));
+        assert_eq!(result.items[2], json!({ "seq": 3, "value": 103 }));
+        assert!(result.window_complete);
+        assert!(!result.truncated);
+        assert!(!result.has_more);
+    }
+
     #[tokio::test]
     async fn rejects_invalid_input_shape() {
         let base_url = spawn_runtime_server().await;
@@ -652,6 +723,43 @@ mod tests {
         format!("http://{}", address)
     }
 
+    async fn spawn_websocket_server() -> String {
+        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+        let address = listener.local_addr().unwrap();
+
+        tokio::spawn(async move {
+            loop {
+                let (stream, _) = listener.accept().await.unwrap();
+                tokio::spawn(async move {
+                    let websocket = accept_async(stream).await.unwrap();
+                    let (mut sink, mut source) = websocket.split();
+
+                    if let Some(message) = source.next().await {
+                        let message = message.unwrap();
+                        if !matches!(message, tokio_tungstenite::tungstenite::Message::Text(_)) {
+                            return;
+                        }
+                    }
+
+                    for payload in [
+                        json!({ "seq": 1, "value": 101 }),
+                        json!({ "seq": 2, "value": 102 }),
+                        json!({ "seq": 3, "value": 103 }),
+                    ] {
+                        sink.send(tokio_tungstenite::tungstenite::Message::Text(
+                            payload.to_string().into(),
+                        ))
+                        .await
+                        .unwrap();
+                    }
+                    let _ = sink.close().await;
+                });
+            }
+        });
+
+        format!("ws://{}", address)
+    }
+
     async fn create_lead(Json(payload): Json<Value>) -> (axum::http::StatusCode, Json<Value>) {
         let should_fail = payload
             .get("fail")
@@ -1168,6 +1276,104 @@ mod tests {
         operation
     }
 
+    fn test_websocket_window_operation(
+        target_url: &str,
+        aggregation_mode: AggregationMode,
+        max_items: Option<u32>,
+    ) -> RuntimeOperation {
+        RuntimeOperation::from(Operation {
+            id: OperationId::new("op_websocket_window_runtime"),
+            name: "telemetry_window_ws".to_owned(),
+            display_name: "Telemetry Window WebSocket".to_owned(),
+            category: "ops".to_owned(),
+            protocol: Protocol::Websocket,
+            status: OperationStatus::Published,
+            version: 1,
+            target: Target::Websocket(WebsocketTarget {
+                url: target_url.to_owned(),
+                subprotocols: Vec::new(),
+                subscribe_message_template: Some(json!({"type":"subscribe","topic":"telemetry"})),
+                unsubscribe_message_template: Some(
+                    json!({"type":"unsubscribe","topic":"telemetry"}),
+                ),
+                static_headers: BTreeMap::new(),
+            }),
+            input_schema: Schema {
+                kind: SchemaKind::Object,
+                description: None,
+                required: true,
+                nullable: false,
+                default_value: None,
+                fields: BTreeMap::new(),
+                items: None,
+                enum_values: Vec::new(),
+                variants: Vec::new(),
+            },
+            output_schema: object_schema("ignored", SchemaKind::String),
+            input_mapping: MappingSet {
+                rules: vec![MappingRule {
+                    source: "$.mcp".to_owned(),
+                    target: "$.request.body".to_owned(),
+                    required: false,
+                    default_value: None,
+                    transform: None,
+                    condition: None,
+                    notes: None,
+                }],
+            },
+            output_mapping: MappingSet { rules: Vec::new() },
+            execution_config: ExecutionConfig {
+                timeout_ms: 1_000,
+                retry_policy: None,
+                auth_profile_ref: None,
+                headers: BTreeMap::new(),
+                protocol_options: Some(ProtocolOptions {
+                    grpc: None,
+                    websocket: Some(WebsocketProtocolOptions {
+                        heartbeat_interval_ms: Some(100),
+                        reconnect_max_attempts: Some(1),
+                        reconnect_backoff_ms: Some(10),
+                    }),
+                }),
+                streaming: Some(StreamingConfig {
+                    mode: ExecutionMode::Window,
+                    transport_behavior: TransportBehavior::ServerStream,
+                    window_duration_ms: Some(2_000),
+                    poll_interval_ms: None,
+                    upstream_timeout_ms: Some(1_000),
+                    idle_timeout_ms: None,
+                    max_session_lifetime_ms: None,
+                    max_items,
+                    max_bytes: None,
+                    aggregation_mode,
+                    summary_path: None,
+                    items_path: Some("$.items".to_owned()),
+                    cursor_path: None,
+                    status_path: None,
+                    done_path: Some("$.done".to_owned()),
+                    redacted_paths: Vec::new(),
+                    truncate_item_fields: false,
+                    max_field_length: None,
+                    drop_duplicates: false,
+                    sampling_rate: None,
+                    tool_family: ToolFamilyConfig::default(),
+                }),
+            },
+            tool_description: ToolDescription {
+                title: "Telemetry Window WebSocket".to_owned(),
+                description: "Collects bounded WebSocket telemetry.".to_owned(),
+                tags: vec!["websocket".to_owned(), "stream".to_owned()],
+                examples: Vec::new(),
+            },
+            samples: None,
+            generated_draft: None,
+            config_export: None,
+            created_at: "2026-04-06T12:00:00Z".to_owned(),
+            updated_at: "2026-04-06T12:00:00Z".to_owned(),
+            published_at: Some("2026-04-06T12:00:00Z".to_owned()),
+        })
+    }
+
     fn test_window_sse_operation(
         base_url: &str,
         aggregation_mode: AggregationMode,
diff --git a/docs/data-model.md b/docs/data-model.md
index 7567f25..3d07c19 100644
--- a/docs/data-model.md
+++ b/docs/data-model.md
@@ -430,6 +430,20 @@
 
 - `kind`
 - `wsdl_ref`
+
+## 5. `ProtocolOptions`
+
+`ProtocolOptions` хранит protocol-specific runtime tuning, который не должен смешиваться с общей `ExecutionConfig`.
+
+### 5.1. `GrpcProtocolOptions`
+
+- `use_tls`
+
+### 5.2. `WebsocketProtocolOptions`
+
+- `heartbeat_interval_ms`
+- `reconnect_max_attempts`
+- `reconnect_backoff_ms`
 - `service_name`
 - `port_name`
 - `operation_name`
diff --git a/docs/protocols/websocket.md b/docs/protocols/websocket.md
index 48b92ca..02b85a4 100644
--- a/docs/protocols/websocket.md
+++ b/docs/protocols/websocket.md
@@ -79,8 +79,6 @@ WebSocket operation должна включать:
 - `url`
 - `headers`
 - `subprotocols`
-- `connect_timeout_ms`
-- `heartbeat_interval_ms`
 - `subscribe_message_template`
 - `unsubscribe_message_template`
 - `input_mapping`
@@ -88,6 +86,12 @@ WebSocket operation должна включать:
 - `execution_config`
 - `tool_description`
 
+Protocol-specific runtime tuning хранится отдельно в `ProtocolOptions.websocket`:
+
+- `heartbeat_interval_ms`
+- `reconnect_max_attempts`
+- `reconnect_backoff_ms`
+
 ## 7. Как оператор настраивает WebSocket operation
 
 1. Указывает URL WebSocket upstream.