diff --git a/api/v3/api_proto/issue_objects.proto b/api/v3/api_proto/issue_objects.proto
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+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
+// This file defines protobufs for issues and related business
+// objects, e.g., field values, comments, and attachments.
+
+syntax = "proto3";
+
+package monorail.v3;
+
+option go_package = "api/v3/api_proto";
+
+import "google/api/field_behavior.proto";
+import "google/api/resource.proto";
+import "google/protobuf/timestamp.proto";
+
+// Represents a comment and any associated changes to an Issue.
+//
+// Comments cannot be Created or Updated through standard methods. The
+// OUTPUT_ONLY annotations here indicate fields that would never be provided
+// by the user even if these methods were made available.
+// Next available tag: 11.
+message Comment {
+
+  // The type of comment.
+  // Next available tag: 9
+  enum Type {
+    // The default comment type. Used if type is omitted.
+    UNSPECIFIED = 0;
+    // A standard comment on an issue.
+    COMMENT = 1;
+    // A comment representing a new description for the issue.
+    DESCRIPTION = 2;
+  }
+
+  // A file attached to a comment.
+  // Next available tag: 8
+  message Attachment {
+    // The name of the attached file.
+    string filename = 1;
+    // It is possible for attachments to be deleted (and undeleted) by the
+    // uploader. The name of deleted attachments are still shown, but the
+    // content is not available.
+    IssueContentState state = 2;
+    // Size of the attached file in bytes.
+    uint64 size = 3;
+    // The type of content contained in the file, using the IANA's media type
+    // https://www.iana.org/assignments/media-types/media-types.xhtml.
+    string media_type = 4;
+    // The URI used for a preview of the attachment (when relelvant).
+    string thumbnail_uri = 5;
+    // The URI used to view the content of the attachment.
+    string view_uri = 6;
+    // The URI used to download the content of the attachment.
+    string download_uri = 7;
+  }
+
+  // This message is only suitable for displaying the amendment to users.
+  // We don't currently offer structured amendments that client code can
+  // reason about, field names can be ambiguous, and we don't have
+  // old_value for most changes.
+  // Next available tag: 4
+  message Amendment {
+    // This may be the name of a built-in or custom field, or relative to
+    // an approval field name.
+    string field_name = 1;
+    // This may be a new value that overwrote the old value, e.g., "Assigned",
+    // or it may be a space-separated list of changes, e.g., "Size-L -Size-S".
+    string new_or_delta_value = 2;
+    // old_value is only used when the user changes the summary.
+    string old_value = 3;
+  }
+
+  option (google.api.resource) = {
+    type: "api.crbug.com/Comment"
+    pattern: "projects/{project}/issues/{issue}/comments/{comment}"
+  };
+
+  // Resource name of the comment.
+  string name = 1;
+  // The state of the comment.
+  IssueContentState state = 2 [(google.api.field_behavior) = OUTPUT_ONLY];
+  // The type of comment.
+  Type type = 3;
+  // The text of the comment.
+  string content = 4;
+  // Resource name of the author of the comment.
+  string commenter = 5 [
+    (google.api.resource_reference) = { type: "api.crbug.com/User" },
+    (google.api.field_behavior) = OUTPUT_ONLY
+  ];
+  // The time this comment was added to the Issue.
+  google.protobuf.Timestamp create_time = 6
+      [(google.api.field_behavior) = OUTPUT_ONLY];
+  // Optional string full text of an email that caused this comment to be added.
+  string inbound_message = 7 [(google.api.field_behavior) = OUTPUT_ONLY];
+  // The approval this comment is associated with, if applicable.
+  string approval = 8
+      [(google.api.resource_reference) = { type: "api.crbug.com/ApprovalValue" }];
+  // Any changes made to the issue in association with this comment.
+  repeated Amendment amendments = 9 [(google.api.field_behavior) = OUTPUT_ONLY];
+  // Any attachments uploaded in association with this comment.
+  repeated Attachment attachments = 10
+      [(google.api.field_behavior) = OUTPUT_ONLY];
+}
+
+
+// Many values on an issue can be set either explicitly or by a rule.
+//
+// Note: Though Derivations are used as OUTPUT_ONLY, values including them
+// will still be ingested even though the Derivation is ignored.
+//
+// Next available tag: 3
+enum Derivation {
+  // The default derivation. This value is used if the derivation is omitted.
+  DERIVATION_UNSPECIFIED = 0;
+  // The value was explicitly set on the issue.
+  EXPLICIT = 1;
+  // Value was auto-applied to the issue based on a project's rule. See
+  // monorail/doc/userguide/project-owners.md#how-to-configure-filter-rules
+  RULE = 2;
+}
+
+
+// A value of a custom field for an issue.
+// Next available tag: 5
+message FieldValue {
+  // The project-defined field associated with this value
+  string field = 1 [
+      (google.api.resource_reference) = { type: "api.crbug.com/FieldDef" }];
+  // The value associated with the field.
+  // Mapping of field types to string value:
+  // ENUM_TYPE(int) => str(value)
+  // INT_TYPE(int) => str(value)
+  // STR_TYPE(str) => value
+  // USER_TYPE(int) => the user's resource name
+  // DATE_TYPE(int) => str(int) representing time in seconds since epoch
+  // URL_TYPE(str) => value
+  string value = 2;
+  // How the value was derived.
+  Derivation derivation = 3 [(google.api.field_behavior) = OUTPUT_ONLY];
+  // Issues with phase-specific fields can have values for each phase.
+  string phase = 4;
+}
+
+// Documents and tracks a bug, task, or feature request within a Project.
+// Next available tag: 23
+message Issue {
+  option (google.api.resource) = {
+    type: "api.crbug.com/Issue"
+    pattern: "projects/{project}/issues/{issue}"
+  };
+
+  // A possibly rule-derived component for the issue.
+  // Next available tag: 3
+  message ComponentValue {
+    // The component.
+    string component = 1 [
+      (google.api.resource_reference) = { type: "api.crbug.com/ComponentDef" }
+    ];
+    // How the component was derived.
+    Derivation derivation = 2 [(google.api.field_behavior) = OUTPUT_ONLY];
+  }
+
+  // A possibly rule-derived label for an issue.
+  // Next available tag: 3
+  message LabelValue {
+    // The label.
+    string label = 1;
+    // How the label was derived.
+    Derivation derivation = 2 [(google.api.field_behavior) = OUTPUT_ONLY];
+  }
+
+  // A possibly rule-derived status for an issue.
+  // Next available tag: 3
+  message StatusValue {
+    // The status of the issue. Note that in rare cases this can be a
+    // value not defined in the project's StatusDefs (e.g. if the issue
+    // was moved from another project).
+    string status = 1;
+    // How the status was derived.
+    Derivation derivation = 2 [(google.api.field_behavior) = OUTPUT_ONLY];
+  }
+
+  // A possibly rule-derived user value on an issue.
+  // Next available tag: 3
+  message UserValue {
+    // The user.
+    string user = 1
+        [(google.api.resource_reference) = { type: "api.crbug.com/User" }];
+    // How the user value was derived.
+    Derivation derivation = 2 [(google.api.field_behavior) = OUTPUT_ONLY];
+  }
+
+  // Resource name of the issue.
+  string name = 1;
+  // A brief summary of the issue. Generally displayed as a user-facing title.
+  // TODO(monorail:6988): The UI limits summary length while the backend does
+  // not. Resolve this discrepancy.
+  string summary = 2;
+  // The state of the issue.
+  IssueContentState state = 3 [(google.api.field_behavior) = OUTPUT_ONLY];
+  // The current status of the issue.
+  StatusValue status = 4 [(google.api.field_behavior) = REQUIRED];
+  // The user who created the issue.
+  string reporter = 5 [
+    (google.api.resource_reference) = { type: "api.crbug.com/User" },
+    (google.api.field_behavior) = OUTPUT_ONLY
+  ];
+  // The user currently responsible for the issue. This user must be a member of
+  // the Project.
+  UserValue owner = 6;
+  // Additional users receiving notifications on the issue.
+  repeated UserValue cc_users = 7;
+  // Labels applied to the issue.
+  repeated LabelValue labels = 8;
+  // Components the issue is associated with.
+  repeated ComponentValue components = 9;
+  // Values for custom fields on the issue.
+  repeated FieldValue field_values = 10;
+  // An issue can be merged into another. If this value is set, the issue
+  // referred to should be considered the primary source for further updates.
+  IssueRef merged_into_issue_ref = 11;
+  // Issues preventing the completion of this issue.
+  repeated IssueRef blocked_on_issue_refs = 12;
+  // Issues for which this issue is blocking completion.
+  repeated IssueRef blocking_issue_refs = 13;
+  // The time the issue was reported.
+  google.protobuf.Timestamp create_time = 14
+      [(google.api.field_behavior) = OUTPUT_ONLY];
+  // The most recent time the issue was closed.
+  google.protobuf.Timestamp close_time = 15
+      [(google.api.field_behavior) = OUTPUT_ONLY];
+  // The most recent time the issue was modified.
+  google.protobuf.Timestamp modify_time = 16
+      [(google.api.field_behavior) = OUTPUT_ONLY];
+  // The most recent time a component value was modified.
+  google.protobuf.Timestamp component_modify_time = 17
+      [(google.api.field_behavior) = OUTPUT_ONLY];
+  // The most recent time the status value was modified.
+  google.protobuf.Timestamp status_modify_time = 18
+      [(google.api.field_behavior) = OUTPUT_ONLY];
+  // The most recent time the owner made a modification to the issue.
+  google.protobuf.Timestamp owner_modify_time = 19
+      [(google.api.field_behavior) = OUTPUT_ONLY];
+  // The number of attachments associated with the issue.
+  uint32 attachment_count = 20 [(google.api.field_behavior) = OUTPUT_ONLY];
+  // The number of users who have starred the issue.
+  uint32 star_count = 21 [(google.api.field_behavior) = OUTPUT_ONLY];
+  // Phases of a process the issue is tracking (if applicable).
+  // See monorail/doc/userguide/concepts.md#issue-approvals-and-gates
+  repeated string phases = 22 [
+      (google.api.field_behavior) = OUTPUT_ONLY];
+}
+
+// States that an issue or its comments can be in (aip.dev/216).
+// Next available tag: 4
+enum IssueContentState {
+  // The default value. This value is used if the state is omitted.
+  STATE_UNSPECIFIED = 0;
+  // The Issue or Comment is available.
+  ACTIVE = 1;
+  // The Issue or Comment has been deleted.
+  DELETED = 2;
+  // The Issue or Comment has been flagged as spam.
+  // Takes precedent over DELETED.
+  SPAM = 3;
+}
+
+// Specifies a column in an issues list view.
+// Next available tag: 2
+message IssuesListColumn {
+  // Column name shown in the column header.
+  string column = 1;
+}
+
+// Refers to an issue that may or may not be tracked in Monorail.
+// At least one of `issue` and `ext_identifier` MUST be set; they MUST NOT both
+// be set.
+// Next available tag: 3
+message IssueRef {
+  // Resource name of an issue tracked in Monorail
+  string issue = 1
+      [(google.api.resource_reference) = { type: "api.crbug.com/Issue" }];
+  // For referencing external issues, e.g. b/1234, or a dangling reference
+  // to an old 'codesite' issue.
+  // TODO(monorail:7208): add more documentation on dangling references.
+  string ext_identifier = 2;
+}
+
+// Documents and tracks an approval process.
+// See monorail/doc/userguide/concepts.md#issue-approvals-and-gates
+// Next available tag: 9
+message ApprovalValue {
+  option (google.api.resource) = {
+     type: "api.crbug.com/ApprovalValue"
+     pattern: "projects/{project}/issues/{issue}/approvalValues/{approval}"
+   };
+
+  // Potential states for an approval. Note that these statuses cause different
+  // sets of notifications. See monorail/doc/userguide/email.md
+  // Next available tag: 9
+  enum ApprovalStatus {
+    // The default approval status. This value is used if the status is omitted.
+    APPROVAL_STATUS_UNSPECIFIED = 0;
+    // No status has yet been set on this value.
+    NOT_SET = 1;
+    // This issue needs review from the approvers for this phase.
+    NEEDS_REVIEW = 2;
+    // This approval is not needed for this issue for this phase.
+    NA = 3;
+    // The issue is ready for the approvers to review.
+    REVIEW_REQUESTED = 4;
+    // The approvers have started reviewing this issue.
+    REVIEW_STARTED = 5;
+    // The approvers need more information.
+    NEED_INFO = 6;
+    // The approvers have approved this issue for this phase.
+    APPROVED = 7;
+    // The approvers have indicated this issue is not approved for this phase.
+    NOT_APPROVED = 8;
+  }
+
+  // The resource name.
+  string name = 1;
+  // The resource name of the ApprovalDef.
+  string approval_def = 2 [
+      (google.api.resource_reference) = { type: "api.crbug.com/ApprovalDef" },
+      (google.api.field_behavior) = OUTPUT_ONLY];
+  // The users able to grant this approval.
+  repeated string approvers = 3 [
+      (google.api.resource_reference) = { type: "api.crbug.com/User" }];
+  // The current status of the approval.
+  ApprovalStatus status = 4;
+  // The time `status` was last set.
+  google.protobuf.Timestamp set_time = 5 [
+      (google.api.field_behavior) = OUTPUT_ONLY];
+  // The user who most recently set `status`.
+  string setter = 6 [
+      (google.api.resource_reference) = { type: "api.crbug.com/User" },
+      (google.api.field_behavior) = OUTPUT_ONLY];
+  // The phase the approval is associated with (if applicable).
+  string phase = 7 [
+      (google.api.field_behavior) = OUTPUT_ONLY];
+  // FieldValues with `approval_def` as their parent.
+  repeated FieldValue field_values = 8;
+}
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