// SPDX-FileCopyrightText: Copyright (c) 2025-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
// SPDX-License-Identifier: Apache-2.0

syntax = "proto3";

package openshell.middleware.v1;

import "google/protobuf/struct.proto";
import "google/protobuf/duration.proto";
import "extension.proto";

// SupervisorMiddleware discovers and configures one operator-run middleware.
// It evaluates HTTP requests and WebSocket messages before credentials.
// Phase-specific services share the same registration.
service SupervisorMiddleware {
  // Describe returns the service manifest and declared bindings.
  rpc Describe(MiddlewareDescribeRequest) returns (MiddlewareManifest);

  // ValidateConfig checks service-specific configuration for one binding.
  rpc ValidateConfig(ValidateConfigRequest) returns (ValidateConfigResponse);

  // EvaluateHttpRequest returns an allow, deny, or mutation decision for one
  // buffered HTTP request.
  rpc EvaluateHttpRequest(HttpRequestEvaluation) returns (HttpRequestResult);

  // EvaluateWebSocketSession opens one ordered, phase-specific stream for a
  // single middleware stage and WebSocket upgrade attempt. The current
  // implementation supports client-to-upstream text messages at
  // PRE_CREDENTIALS; PRE_RETURN is reserved for upstream-to-client messages.
  // A request may go unanswered when the session terminates. For every opened
  // stage stream, OpenShell attempts at most one session_end before closing the
  // stream when its transport is still writable.
  rpc EvaluateWebSocketSession(stream WebSocketSessionEvent)
      returns (stream WebSocketSessionEventResult);
}

message MiddlewareDescribeRequest {
  // Gateway or supervisor protocol metadata. Middleware must reject unmet
  // requirements before accepting traffic.
  openshell.extension.v1.PeerMetadata gateway = 1;
}

// HttpResponsePreReturn evaluates one response for one middleware stage before
// OpenShell returns it to the sandbox.
service HttpResponsePreReturn {
  // Evaluate starts with preflight and may continue with selected body units
  // and trailers. A body unit marked end_of_stream ends body inspection, not
  // the event stream. Trailers and one best-effort session_end may follow.
  rpc Evaluate(stream HttpResponseEvent)
      returns (stream HttpResponseEventResult);
}

// MiddlewareManifest describes one middleware service and its bindings.
message MiddlewareManifest {
  // Human-readable middleware service name used only for diagnostics. This is
  // not required to match an operator-owned registration name.
  string name = 1;
  // Deprecated diagnostic compatibility field. Use
  // extension.implementation_version.
  string service_version = 2;
  // Bindings exposed by this middleware service.
  repeated MiddlewareBinding bindings = 3;
  // Exact JWT audience this service verifies on inbound OpenShell calls.
  // After authenticated Describe succeeds, OpenShell rejects the registration
  // unless this matches the operator-configured audience. A strict verifier may
  // reject an incorrect audience before returning this manifest. Empty skips
  // this post-authentication consistency check.
  string expected_audience = 4;
  // Supervisor-middleware protocol metadata. Required for negotiation.
  // Declare protocol 1.0 and list "openshell.supervisor-middleware.contract"
  // in supported_capabilities.
  openshell.extension.v1.PeerMetadata extension = 5;
}

// MiddlewareBinding declares one operation and phase supported by a service.
message MiddlewareBinding {
  reserved 4;
  reserved "timeout";
  // Supported operation.
  SupervisorMiddlewareOperation operation = 1;
  // Supported phase.
  SupervisorMiddlewarePhase phase = 2;
  // Maximum request body, WebSocket message, or response body unit/replacement.
  // Required for payload-bearing operations.
  uint64 max_payload_bytes = 3;
  // Optional binding-specific RPC timeout. Empty uses the operator-configured
  // service timeout, or the 500ms platform default when that is also omitted.
  // A non-empty value may shorten but cannot extend the operator timeout.
  // Values must be between 10ms and 30s.
  google.protobuf.Duration request_timeout = 104;
}

// ValidateConfigRequest contains one policy configuration to validate.
message ValidateConfigRequest {
  // Service-specific policy configuration.
  google.protobuf.Struct config = 1;
  // Built-in middleware name or operator-owned registration name.
  string middleware_name = 2;
}

// ValidateConfigResponse reports whether a policy configuration is accepted.
message ValidateConfigResponse {
  // True when the service accepts the configuration.
  bool valid = 1;
  // Human-readable validation failure reason. Empty when valid is true.
  string reason = 2;
}

// HttpRequestEvaluation contains one buffered HTTP request to evaluate.
message HttpRequestEvaluation {
  // Evaluation phase selected for this request.
  SupervisorMiddlewarePhase phase = 1;
  // Sandbox and request identity available to the supervisor.
  // The encoded context is limited to 4 KiB.
  RequestContext context = 2;
  // Validated service-specific policy configuration.
  // The encoded configuration is limited to 64 KiB.
  google.protobuf.Struct config = 3;
  // Destination and HTTP request target.
  // The encoded target is limited to 32 KiB.
  HttpRequestTarget target = 4;
  // HTTP request headers before OpenShell injects credentials, in wire
  // order. Repeated header names are preserved as separate entries. Protected
  // credential, routing, framing, and hop-by-hop headers are omitted.
  // At most 128 lines and 64 KiB of encoded headers are included.
  repeated HttpHeader headers = 5;
  // Buffered request body, limited to 4 MiB. Empty for a bodyless request.
  bytes body = 6;
  // Built-in middleware name or operator-owned registration name.
  string middleware_name = 7;
}

// HttpHeader is one HTTP header line.
message HttpHeader {
  // Lowercased header name.
  string name = 1;
  // Header value with surrounding whitespace trimmed.
  string value = 2;
}

// One ordered response event. A stream starts with preflight, may continue with
// body units ending in end_of_stream, may then include trailers, and may end
// with one best-effort session_end.
message HttpResponseEvent {
  oneof event {
    // Initial response head and request context.
    HttpResponsePreflight preflight = 1;
    // Next normalized body unit.
    HttpResponseBodyUnit body = 2;
    // Normalized trailers after the final body result.
    HttpResponseTrailers trailers = 4;
    // Optional terminal notification.
    MiddlewareSessionEnd session_end = 3;
  }
}

// Each preflight, body, and trailers event requires one ordered result.
// session_end has no result.
message HttpResponseEventResult {
  oneof result {
    // Result for preflight.
    HttpResponsePreflightResult preflight_result = 1;
    // Result for the next body unit.
    HttpResponseBodyResult body_result = 2;
    // Result for response trailers.
    HttpResponseTrailersResult trailers_result = 3;
  }
}

// HttpResponsePreflight exposes the current final response head to one stage.
message HttpResponsePreflight {
  // Request identity. request_id links request and response evaluations.
  // Limited to 4 KiB encoded.
  RequestContext context = 1;
  // Admitted request target with a redacted query. Limited to 32 KiB encoded.
  HttpRequestTarget target = 2;
  // Final non-informational upstream status. Upgrades are not evaluated.
  uint32 status_code = 3;
  // Response headers after prior stages, in wire order. Repeated names remain
  // separate. Credential, routing, and hop-by-hop headers are omitted.
  // Content-Length, Content-Encoding, and Content-Range retain their read-only
  // upstream values. OpenShell may recompute or remove Content-Length later.
  // Limited to 128 lines and 64 KiB encoded.
  repeated HttpHeader headers = 4;
  // Built-in middleware name or operator-owned registration name.
  string middleware_name = 5;
  // Validated service configuration. Limited to 64 KiB encoded.
  google.protobuf.Struct config = 6;
  // Effective minimum of platform, registration, and binding limits. Applies to
  // whole-body input/replacement and each stream input/replacement. Stream
  // inputs use at most min(64 KiB, max_payload_bytes).
  uint64 max_payload_bytes = 7;
  // Modes derived independently for this stage. OpenShell first determines
  // response-shape eligibility from the original final response head, then
  // applies this stage's effective max_payload_bytes. Different stages may
  // receive different lists. HEADERS_ONLY is always present and is the only
  // mode for bodyless, partial, encoded, or no-transform responses. For an
  // otherwise eligible response, a known body larger than this stage's limit
  // omits WHOLE_BODY_BYTES. An eligible unknown-length response may select
  // WHOLE_BODY_BYTES and later fail with whole_body_over_capacity according to
  // this stage's on_error. STREAM_BYTES is omitted when
  // max_payload_bytes is zero. Selecting an unlisted mode fails according to
  // on_error.
  repeated HttpResponseBodyMode permitted_body_modes = 8;
}

// Selects skip, inspect, or block. Diagnostic fields apply to every action.
// Invalid diagnostics make the entire result a middleware failure handled
// according to on_error.
message HttpResponsePreflightResult {
  oneof action {
    // Deliver unchanged without invoking on_error.
    HttpResponsePreflightSkip skip = 1;
    // Inspect with the selected body mode and mutations.
    HttpResponsePreflightInspect inspect = 2;
    // Prevent delivery to the sandbox.
    HttpResponseBlockDelivery block_delivery = 7;
  }
  // Service diagnostic, never sent to the sandbox or security logs. Maximum
  // 4 KiB.
  string reason = 3;
  // Optional audit code using the HttpRequestResult.reason_code format and
  // 64-byte maximum. Returned to the sandbox only for block_delivery.
  string reason_code = 4;
  // Up to 32 audit-safe findings, each limited to 4 KiB encoded.
  repeated Finding findings = 5;
  // Non-secret diagnostic metadata, limited to 64 entries and 32 KiB.
  map<string, string> metadata = 6;
}

// Ends this stage successfully without body inspection.
message HttpResponsePreflightSkip {}

// Blocks delivery as a successful decision regardless of on_error. OpenShell
// evaluates results in policy order. Once it accepts a valid block, it stops
// later middleware evaluation and ends every still-writable opened stage with
// MIDDLEWARE_DENIAL. A failure handled earlier may already have stopped
// evaluation, so a later block does not override it. An invalid block result
// is a middleware failure handled according to on_error. The upstream request
// has already run; blocking its response does not reject or roll back that
// request.
//
// Before response commitment, including at preflight and during
// WHOLE_BODY_BYTES, OpenShell replaces the upstream response with the canonical
// 403 Forbidden middleware-denial response. Its JSON body has
// error = "middleware_denied" and includes a validated reason_code when the
// result supplies one. OpenShell never returns the free-form reason or writes it
// to security logs. For HEAD, OpenShell sends the canonical response headers
// and Content-Length but no body. It closes the downstream connection after the
// denial response.
//
// After response commitment, including during STREAM_BYTES, OpenShell aborts
// downstream delivery. It does not inject an error body, a terminating chunk,
// or an error trailer. OpenShell does not reuse the upstream connection.
message HttpResponseBlockDelivery {}

// Selects body inspection and response-header mutations.
message HttpResponsePreflightInspect {
  // Required mode from permitted_body_modes. Invalid values fail according to
  // on_error.
  HttpResponseBodyMode body_mode = 1;
  // Ordered mutations applied atomically before the next stage. Only visible
  // end-to-end headers may change. Routing, credential, framing, coding, range,
  // and hop-by-hop headers are protected; integrity headers may only be removed.
  // Limited to 64 operations, 32 KiB of name/value data, and 64 KiB encoded.
  repeated HeaderMutation header_mutations = 2;
}

// Controls which response-body units a stage receives.
enum HttpResponseBodyMode {
  // Invalid value handled according to on_error.
  HTTP_RESPONSE_BODY_MODE_UNSPECIFIED = 0;
  // Inspect only the response head.
  HTTP_RESPONSE_BODY_MODE_HEADERS_ONLY = 1;
  // Buffer the normalized body as one final unit before committing the head.
  // Input and replacement must fit max_payload_bytes. Capacity failures use
  // whole_body_over_capacity and follow this stage's on_error.
  HTTP_RESPONSE_BODY_MODE_WHOLE_BODY_BYTES = 2;
  // Receive normalized units ending with end_of_stream. Each input is at most
  // min(64 KiB, max_payload_bytes), and each replacement must fit
  // max_payload_bytes. Each result fully accounts for its input unit; V1 does
  // not permit retaining input across units. The full body may exceed the
  // limit. STREAM_BYTES has no total response-lifetime deadline.
  HTTP_RESPONSE_BODY_MODE_STREAM_BYTES = 3;
}

// One normalized body unit. Boundaries have no transport or application
// meaning.
message HttpResponseBodyUnit {
  // Contiguous and stage-local, starting at 1.
  uint64 sequence = 1;
  oneof payload {
    // Bytes without transfer framing. A body-capable response with no body bytes
    // has present empty data in sequence 1. STREAM_BYTES input size is at most
    // min(64 KiB, max_payload_bytes). A unit may be shorter to preserve
    // flushing.
    bytes data = 2;
  }
  // Marks the final body unit. Every normally completed body inspection receives
  // exactly one. For a body-capable response with no body bytes, this is the
  // empty sequence-1 unit. OpenShell does not read ahead, so it may send an empty
  // final unit after the last nonempty unit. Trailers and session_end may
  // follow. A stage ended by skip_remaining, block, or failure receives no
  // later final unit.
  bool end_of_stream = 3;
}

// Result for one body unit. Units are processed in lockstep; V1 does not
// support ownership transfer or cross-unit retention. Diagnostic fields apply
// to every action. Invalid diagnostics make the entire result a middleware
// failure handled according to on_error. OpenShell retains the current input
// until it validates the result, so fail-open can continue from the last input
// OpenShell still owns.
message HttpResponseBodyResult {
  // Must match the next unit. Zero, gaps, duplicates, and regressions fail.
  uint64 sequence = 1;
  // Exactly one explicit action is required.
  oneof action {
    // Forward the input unit unchanged.
    HttpResponseBodyPassThrough pass_through = 2;
    // Replace the complete input unit.
    HttpResponseBodyTransform transform = 3;
    // Stop delivery. See HttpResponseBlockDelivery.
    HttpResponseBlockDelivery block_delivery = 8;
    // Finalize this unit and stop inspecting.
    HttpResponseBodySkipRemaining skip_remaining = 9;
  }
  // Service diagnostic, never sent to the sandbox or security logs. Maximum
  // 4 KiB.
  string reason = 4;
  // Optional audit code using the HttpRequestResult.reason_code format and
  // 64-byte maximum. When OpenShell accepts block_delivery before response
  // commitment, it includes this code in the canonical denial response. It is
  // never returned after commitment.
  string reason_code = 5;
  // Up to 32 audit-safe findings, each limited to 4 KiB encoded.
  repeated Finding findings = 6;
  // Non-secret diagnostic metadata, limited to 64 entries and 32 KiB.
  map<string, string> metadata = 7;
}

// Preserves the input unit.
message HttpResponseBodyPassThrough {}

// Finalizes this unit and ends the stage. This stage receives no later body or
// trailer events. The current and later units continue through other stages.
// For WHOLE_BODY_BYTES, this equals its nested action.
message HttpResponseBodySkipRemaining {
  // Exactly one action for the current unit.
  oneof current {
    // Forward the current unit unchanged.
    HttpResponseBodyPassThrough pass_through = 1;
    // Replace the current unit.
    HttpResponseBodyTransform transform = 2;
  }
}

// Replaces the complete input unit.
message HttpResponseBodyTransform {
  // Required replacement, limited to max_payload_bytes. Present empty data
  // deletes the input unit. The replacement fully accounts for this input unit;
  // middleware must not retain input bytes for a later unit in V1.
  oneof replacement {
    // Normalized replacement bytes.
    bytes data = 1;
  }
}

// The current normalized response trailers in wire order. Repeated names stay
// as separate fields. A stage that completes WHOLE_BODY_BYTES or STREAM_BYTES
// receives exactly one trailers event after its final body result, including
// when this set is empty. SKIP, HEADERS_ONLY, semantically bodyless responses,
// and stages ended by block, failure, or skip_remaining receive no trailers.
message HttpResponseTrailers {
  repeated HttpHeader headers = 1;
}

// Applies ordered trailer mutations atomically. An empty mutation list
// preserves the current trailers. A write may target only a case-insensitive
// name present in the trailers event; V1 cannot create a trailer name. Removal
// of an absent name is a no-op. Credential, routing, framing, coding, range,
// hop-by-hop, and connection-nominated fields are protected. Diagnostic fields
// apply whether mutations are empty or nonempty. Invalid diagnostics or
// mutations make the entire result a middleware failure handled according to
// on_error.
message HttpResponseTrailersResult {
  // At most 64 operations, 32 KiB of validated name/value data, and 64 KiB
  // encoded are accepted.
  repeated HeaderMutation trailer_mutations = 1;
  // Service diagnostic, never sent to the sandbox or security logs. Maximum
  // 4 KiB.
  string reason = 2;
  // Optional audit code using the HttpRequestResult.reason_code format and
  // 64-byte maximum. Never sent to the sandbox.
  string reason_code = 3;
  // Up to 32 audit-safe findings, each limited to 4 KiB encoded.
  repeated Finding findings = 4;
  // Non-secret diagnostic metadata, limited to 64 entries and 32 KiB.
  map<string, string> metadata = 5;
}

// Stable reason OpenShell ended a middleware stage stream.
enum MiddlewareSessionEndReason {
  // Invalid reason.
  MIDDLEWARE_SESSION_END_REASON_UNSPECIFIED = 0;
  // Evaluation completed.
  MIDDLEWARE_SESSION_END_REASON_NORMAL = 1;
  // The sandbox peer disconnected.
  MIDDLEWARE_SESSION_END_REASON_DOWNSTREAM_DISCONNECT = 2;
  // A policy reload replaced the active middleware chain.
  MIDDLEWARE_SESSION_END_REASON_POLICY_RELOAD = 3;
  // A stage denied the operation or blocked the response.
  MIDDLEWARE_SESSION_END_REASON_MIDDLEWARE_DENIAL = 4;
  // A selected stage failed.
  MIDDLEWARE_SESSION_END_REASON_MIDDLEWARE_FAILURE = 5;
  // A proxied or middleware protocol was violated.
  MIDDLEWARE_SESSION_END_REASON_PROTOCOL_ERROR = 6;
  // Evaluation was canceled for another reason.
  MIDDLEWARE_SESSION_END_REASON_CANCELLATION = 7;
  // Upstream rejected or failed before a valid response or upgrade.
  MIDDLEWARE_SESSION_END_REASON_UPSTREAM_FAILURE = 8;
  // Network policy denied the operation.
  MIDDLEWARE_SESSION_END_REASON_POLICY_DENIAL = 9;
  // The stage successfully declined inspection during preflight.
  MIDDLEWARE_SESSION_END_REASON_STAGE_SKIPPED = 10;
  // Upstream disconnected after a valid response or upgrade.
  MIDDLEWARE_SESSION_END_REASON_UPSTREAM_DISCONNECT = 11;
}

// Best-effort terminal notification. A stage receives at most one and sends no
// result.
message MiddlewareSessionEnd {
  // Terminal reason. Producers never send UNSPECIFIED.
  MiddlewareSessionEndReason reason = 1;
  // Set only for PROTOCOL_ERROR. Missing or unknown details mean a generic
  // protocol error.
  MiddlewareSessionProtocolError protocol_error = 2;
}

// Details for a protocol-error session end.
message MiddlewareSessionProtocolError {
  oneof domain {
    // WebSocket protocol violation.
    WebSocketProtocolError web_socket = 1;
    // Middleware event/result protocol violation.
    MiddlewareExchangeProtocolError middleware_exchange = 2;
  }
}

// WebSocket protocol error details, reserved for future categories.
message WebSocketProtocolError {}

// Middleware exchange error details, reserved for future categories.
message MiddlewareExchangeProtocolError {}

// Supervisor operation selected for middleware evaluation.
enum SupervisorMiddlewareOperation {
  SUPERVISOR_MIDDLEWARE_OPERATION_UNSPECIFIED = 0;
  SUPERVISOR_MIDDLEWARE_OPERATION_HTTP_REQUEST = 1;
  SUPERVISOR_MIDDLEWARE_OPERATION_WEBSOCKET_MESSAGE = 2;
  SUPERVISOR_MIDDLEWARE_OPERATION_HTTP_RESPONSE = 3;
}

// Ordered phase within a supervisor operation.
enum SupervisorMiddlewarePhase {
  SUPERVISOR_MIDDLEWARE_PHASE_UNSPECIFIED = 0;
  SUPERVISOR_MIDDLEWARE_PHASE_PRE_CREDENTIALS = 1;
  SUPERVISOR_MIDDLEWARE_PHASE_PRE_RETURN = 2;
}

// WebSocketSessionEvent is one ordered event in a stage-local stream.
// Message sequence numbers identify logical messages session-wide. A stage
// receives a strictly increasing subset of those numbers; gaps are valid when
// session messages are not delivered to that stage.
message WebSocketSessionEvent {
  oneof event {
    WebSocketPreflight preflight = 1;
    WebSocketSessionStart session_start = 2;
    WebSocketMessage message = 3;
    MiddlewareSessionEnd session_end = 4;
  }
}

// WebSocketPreflight lets a service decline this upgrade before OpenShell
// contacts upstream. It deliberately excludes query data, arbitrary request
// headers, and message payloads.
message WebSocketPreflight {
  string session_id = 1;
  SupervisorMiddlewarePhase phase = 2;
  RequestContext context = 3;
  // Admitted HTTP WebSocket-upgrade target. The method is GET, query is always
  // empty, and path never includes a query string.
  HttpRequestTarget target = 4;
  repeated string requested_subprotocols = 5;
  // Built-in middleware name or operator-owned registration name.
  string middleware_name = 6;
  google.protobuf.Struct config = 7;
}

// WebSocketSessionStart reports bounded metadata known only after the
// upstream 101 response validates. Empty selected_subprotocol means none.
message WebSocketSessionStart {
  string selected_subprotocol = 1;
}

// WebSocketMessage contains one complete reconstructed logical message.
message WebSocketMessage {
  // Session-global sequence starting at 1. Values delivered to one stage must
  // strictly increase but need not be contiguous. Reject zero, duplicates, and
  // regressions; accept gaps.
  uint64 sequence = 1;
  // One complete logical payload. Protobuf string decoding enforces UTF-8 for
  // text messages. Raw frame mechanics are never exposed. Limited to 4 MiB by
  // the platform and the binding-specific cap.
  oneof payload {
    string text = 2;
    bytes binary = 3;
  }
}

// WebSocketPreflightAction is the service's one-time scoping decision.
enum WebSocketPreflightAction {
  // Invalid response value handled according to the policy failure mode.
  WEB_SOCKET_PREFLIGHT_ACTION_UNSPECIFIED = 0;
  // Inspect this session after the upstream accepts the upgrade.
  WEB_SOCKET_PREFLIGHT_ACTION_INSPECT = 1;
  // Voluntarily decline inspection without denying the upgrade. This is a
  // successful decision and does not engage on_error.
  WEB_SOCKET_PREFLIGHT_ACTION_SKIP = 2;
  // Authoritatively deny the upgrade before upstream contact. This is a
  // successful decision and is enforced regardless of on_error.
  WEB_SOCKET_PREFLIGHT_ACTION_DENY = 3;
}

message WebSocketPreflightDecision {
  WebSocketPreflightAction action = 1;
  // Free-form service diagnostic. OpenShell never exposes this to the
  // workload or security logs. Limited to 4 KiB before discarding.
  string reason = 2;
  // Optional stable machine-readable code for a deny decision. Because
  // preflight runs before the HTTP upgrade completes, OpenShell may return
  // this code to the requester. Codes follow the same format and 64-byte
  // maximum as HttpRequestResult.reason_code.
  string reason_code = 3;
  // Audit-safe findings produced during preflight. At most 32 findings of at
  // most 4 KiB encoded each are accepted.
  repeated Finding findings = 4;
  // Non-secret service-defined metadata included in diagnostics. At most 64
  // entries and 32 KiB of combined key/value data are accepted.
  map<string, string> metadata = 5;
}

// WebSocketMessageResult contains the decision and optional replacement for
// one message. A replacement must use the same variant as the input payload.
message WebSocketMessageResult {
  // Must exactly match the sequence of the corresponding WebSocketMessage.
  uint64 sequence = 1;
  Decision decision = 2;
  // Absence preserves the input unchanged. Oneof presence distinguishes an
  // empty replacement from no replacement, and string decoding enforces UTF-8.
  oneof replacement {
    string text = 3;
    bytes binary = 4;
  }
  // Free-form service diagnostic. OpenShell never exposes this to the
  // workload or security logs. Limited to 4 KiB before discarding.
  string reason = 5;
  // Optional stable machine-readable code for OCSF only. Unlike the HTTP
  // reason_code, this value is never put in a WebSocket close frame.
  string reason_code = 6;
  repeated Finding findings = 7;
  map<string, string> metadata = 8;
}

// WebSocketSessionEventResult is an evaluation result for a preflight or message
// event. Session start and end events do not produce results.
message WebSocketSessionEventResult {
  oneof result {
    WebSocketPreflightDecision preflight_decision = 1;
    WebSocketMessageResult message_result = 2;
  }
}

// RequestContext identifies the sandbox request being evaluated.
message RequestContext {
  // Request id used to correlate middleware and supervisor logs.
  string request_id = 1;
  // Sandbox id that originated the request.
  string sandbox_id = 2;
  // Workload process that originated the request, when available.
  Process originating_process = 3;
  // Sandbox name that originated the request. For display and logging only.
  // Names are workspace-scoped and may be reused for different sandbox
  // instances, so consumers must use sandbox_id for authorization, persistence,
  // durable correlation, and identity.
  string sandbox = 4;
  // Workspace the sandbox belongs to. For display and logging only; see the
  // sandbox guidance above.
  string workspace = 5;
}

// HttpRequestTarget describes the admitted HTTP destination and request target.
message HttpRequestTarget {
  // Request scheme, such as "http", "https", "ws", or "wss".
  string scheme = 1;
  // Destination hostname selected by network policy.
  string host = 2;
  // Destination TCP port.
  uint32 port = 3;
  // HTTP request method.
  string method = 4;
  // Request path without the query string.
  string path = 5;
  // Raw request query string without the leading question mark.
  string query = 6;
}

// Process identifies a workload process and its executable ancestry.
message Process {
  // Executable path for the originating process.
  string binary = 1;
  // Process id within the sandbox.
  uint32 pid = 2;
  // Executable paths for ancestor processes, nearest parent first.
  repeated string ancestors = 3;
}

// Decision controls whether OpenShell continues processing the current
// evaluation unit.
enum Decision {
  // Invalid response value handled according to the policy failure mode.
  DECISION_UNSPECIFIED = 0;
  // Continue processing the current request or message and apply any returned
  // mutations.
  DECISION_ALLOW = 1;
  // Reject the current request or message. The operation-specific result
  // defines the enclosing protocol behavior.
  DECISION_DENY = 2;
}

// Finding is an audit-safe observation produced during evaluation.
message Finding {
  // Stable, service-defined finding type.
  string type = 1;
  // Human-readable finding label that does not contain request content.
  string label = 2;
  // Number of matching observations represented by this finding.
  uint32 count = 3;
  // Service-defined confidence level.
  string confidence = 4;
  // Service-defined severity level.
  string severity = 5;
}

// ExistingHeaderAction controls how a header write behaves when the
// case-insensitive header name is already present. Every action writes the
// value when the header is absent.
enum ExistingHeaderAction {
  EXISTING_HEADER_ACTION_UNSPECIFIED = 0;
  // Add another field value without changing existing values.
  EXISTING_HEADER_ACTION_APPEND = 1;
  // Remove every existing value, then add the new value.
  EXISTING_HEADER_ACTION_OVERWRITE = 2;
  // Leave the existing values unchanged.
  EXISTING_HEADER_ACTION_SKIP = 3;
}

// WriteHeader proposes one header value and defines collision behavior.
message WriteHeader {
  string name = 1;
  string value = 2;
  ExistingHeaderAction on_existing = 3;
}

// RemoveHeader removes every value for a case-insensitive header name.
message RemoveHeader {
  string name = 1;
}

// HeaderMutation is one ordered HTTP header operation.
message HeaderMutation {
  oneof operation {
    WriteHeader write = 1;
    RemoveHeader remove = 2;
  }
}

// HttpRequestResult contains the decision and optional request mutations.
message HttpRequestResult {
  // Allow or deny decision for this request.
  Decision decision = 1;
  // Free-form service diagnostic. OpenShell does not relay this text into
  // denied responses or security logs. Limited to 4 KiB before discarding.
  string reason = 2;
  // Replacement request body when has_body is true. Limited to 4 MiB.
  bytes body = 3;
  // True when body should replace the request body, including with an empty body.
  bool has_body = 4;
  // Ordered request-header mutations applied before the next middleware and
  // before forwarding. Writes and removals may target visible end-to-end
  // request headers, but credential, routing, framing, and hop-by-hop headers
  // are always protected. Written values cannot contain OpenShell credential
  // placeholder syntax. A violating result is a middleware failure handled
  // according to the policy failure mode. At most 64 operations, 32 KiB of
  // validated name/value data, and 64 KiB encoded are accepted.
  repeated HeaderMutation header_mutations = 5;
  // Audit-safe findings produced during evaluation. For operator-run services,
  // OpenShell logs platform-owned fields derived from the operator-owned
  // registration name rather than service-provided type, label, confidence,
  // or metadata text.
  // At most 32 findings of at most 4 KiB encoded each are accepted per stage.
  // A policy selects at most 10 stages, so one chain retains at most 320.
  repeated Finding findings = 6;
  // Non-secret service-defined metadata included in diagnostics. At most 64
  // entries and 32 KiB of combined key/value data are accepted.
  map<string, string> metadata = 7;
  // Optional stable machine-readable code for a deny decision. Codes must
  // start with a lowercase ASCII letter and contain only lowercase ASCII
  // letters, digits, and underscores, with a maximum length of 64 bytes.
  // OpenShell may return this code to the requester, unlike free-form reason.
  string reason_code = 8;
}