// PROPOSED — kandev.plugin.v1 Host data API (draft for review, not wired yet).
//
// Extends the existing capability-gated Host service so plugins read (and, in a
// second phase, write) kandev data through a typed, versioned contract instead
// of touching the SQLite file directly. These messages are a HAND-DEFINED public
// contract: the backend maps internal models → these DTOs explicitly. Do NOT
// generate them from domain structs — the mapping IS the decoupling.
//
// Enforcement (host side): each RPC checks the caller plugin's manifest
// capabilities. Reads require `api_read: ["<resource>"]`; writes require
// `api_write: ["<resource>"]`. Undeclared → gRPC PermissionDenied
// "capability 'api_read:tasks' not declared". Writes go through the service
// layer (which publishes task.* events), never the repository.

syntax = "proto3";
package kandev.plugin.v1;

import "google/protobuf/struct.proto";

// ── Added to the existing `service Host` (state/secrets/emit already there) ──
service HostData {
  // Reads — capability api_read:<resource>
  rpc ListTasks(ListTasksRequest) returns (ListTasksResponse);
  rpc GetTask(GetTaskRequest) returns (GetTaskResponse);
  rpc ListWorkspaces(ListWorkspacesRequest) returns (ListWorkspacesResponse);
  rpc ListWorkflows(ListWorkflowsRequest) returns (ListWorkflowsResponse);
  rpc ListWorkflowSteps(ListWorkflowStepsRequest) returns (ListWorkflowStepsResponse);
  rpc ListAgentProfiles(ListAgentProfilesRequest) returns (ListAgentProfilesResponse);
  rpc ListRepositories(ListRepositoriesRequest) returns (ListRepositoriesResponse);

  // Sessions + code stats — capability api_read:sessions. Driven by a real
  // plugin (kandev-plugin-agent-stats) that otherwise read task_sessions,
  // task_session_commits, and task_session_git_snapshots straight from the
  // SQLite file. SessionCodeStats is a COMPUTED, stable DTO — deliberately not
  // the raw commit/snapshot rows, whose JSON schema churns.
  rpc ListSessions(ListSessionsRequest) returns (ListSessionsResponse);
  rpc ListSessionCodeStats(ListSessionCodeStatsRequest) returns (ListSessionCodeStatsResponse);

  // Writes — capability api_write:<resource>. Route through service methods so
  // the corresponding task.* events fire; this is the whole reason not to let
  // plugins write the DB.
  rpc CreateTask(CreateTaskRequest) returns (CreateTaskResponse);
  rpc UpdateTask(UpdateTaskRequest) returns (UpdateTaskResponse);
  rpc CreateComment(CreateCommentRequest) returns (CreateCommentResponse);
}

// ── Common ──────────────────────────────────────────────────────────────────
// Pagination is opaque-cursor based so the server can change the underlying
// ordering/store without breaking plugins.
message Page {
  int32 limit = 1;       // 0 → server default (e.g. 50); server caps the max
  string cursor = 2;     // empty → first page; echo next_cursor to continue
}
message PageInfo { string next_cursor = 1; bool has_more = 2; }

// Timestamps are RFC3339 strings (matches the JSON API + the Event envelope
// convention), not protobuf Timestamp, to keep one time representation across
// the whole plugin contract. Optional string fields use `optional` so absent
// (NULL) is distinguishable from empty.

// ── Task ────────────────────────────────────────────────────────────────────
message Task {
  string id = 1;
  string workspace_id = 2;
  string workflow_id = 3;
  string title = 4;
  string description = 5;
  string state = 6;                 // TaskState enum value as a string, stable
  string priority = 7;
  string created_by = 8;
  string created_at = 9;            // RFC3339
  string updated_at = 10;
  optional string started_at = 11;
  optional string completed_at = 12;
  optional string parent_id = 13;
  string identifier = 14;
  bool is_ephemeral = 15;
  repeated TaskRepository repositories = 16;
  google.protobuf.Struct metadata = 17;  // free-form; plugin-tolerant
}
message TaskRepository {
  string id = 1;
  string repository_id = 2;
  string base_branch = 3;
  int32 position = 4;
}

message TaskFilter {
  repeated string workspace_ids = 1;   // empty → all the plugin may see
  repeated string workflow_ids = 2;
  repeated string states = 3;
  optional string parent_id = 4;
  bool include_ephemeral = 5;           // default false (kanban-visible only)
}
message ListTasksRequest { TaskFilter filter = 1; Page page = 2; }
message ListTasksResponse { repeated Task tasks = 1; PageInfo page_info = 2; }
message GetTaskRequest { string id = 1; }
message GetTaskResponse { Task task = 1; }

// ── Workspace / Workflow / Steps ─────────────────────────────────────────────
message Workspace {
  string id = 1;
  string name = 2;
  optional string description = 3;
  string owner_id = 4;
  optional string default_executor_id = 5;
  optional string default_agent_profile_id = 6;
  string created_at = 7;
  string updated_at = 8;
}
message ListWorkspacesRequest { Page page = 1; }
message ListWorkspacesResponse { repeated Workspace workspaces = 1; PageInfo page_info = 2; }

message Workflow {
  string id = 1;
  string workspace_id = 2;
  string name = 3;
  optional string description = 4;
  int32 sort_order = 5;
  string created_at = 6;
  string updated_at = 7;
}
message ListWorkflowsRequest { string workspace_id = 1; Page page = 2; }
message ListWorkflowsResponse { repeated Workflow workflows = 1; PageInfo page_info = 2; }

message WorkflowStep {
  string id = 1;
  string workflow_id = 2;
  string name = 3;
  int32 position = 4;
  string stage_type = 5;            // work | review | approval | custom
}
message ListWorkflowStepsRequest { string workflow_id = 1; }
message ListWorkflowStepsResponse { repeated WorkflowStep steps = 1; }

// ── Agent profiles / Repositories (read-only context) ────────────────────────
message AgentProfile {
  string id = 1;
  string agent_id = 2;
  string display_name = 3;
  string name = 4;
  string model = 5;
  string mode = 6;
}
message ListAgentProfilesRequest { Page page = 1; }
message ListAgentProfilesResponse { repeated AgentProfile profiles = 1; PageInfo page_info = 2; }

message Repository {
  string id = 1;
  string workspace_id = 2;
  string name = 3;                  // owner/repo slug when known, else name
  optional string default_branch = 4;
}
message ListRepositoriesRequest { string workspace_id = 1; Page page = 2; }
message ListRepositoriesResponse { repeated Repository repositories = 1; PageInfo page_info = 2; }

// ── Sessions ─────────────────────────────────────────────────────────────────
// Identity + agent context for one agent run on a task. acp_session_id is the
// join key an external usage tool (e.g. tokscale) uses to attribute tokens — so
// kandev exposes it and stays out of the token business entirely.
message Session {
  string id = 1;
  string task_id = 2;
  string agent_profile_id = 3;
  string agent_display_name = 4;   // from the profile snapshot at run time
  string model = 5;                // resolved model at run time
  string acp_session_id = 6;       // external usage-attribution join key
  string state = 7;
  string started_at = 8;
  optional string ended_at = 9;
  string agent_profile_name = 10;  // profile name from the snapshot at run time
}
message SessionFilter {
  repeated string task_ids = 1;
  repeated string workspace_ids = 2;
  repeated string states = 3;
}
message ListSessionsRequest { SessionFilter filter = 1; Page page = 2; }
message ListSessionsResponse { repeated Session sessions = 1; PageInfo page_info = 2; }

// Computed code metrics per session — the aggregate the agent-stats plugin
// re-derived by hand from commits + git snapshots. Exposed as a stable shape so
// plugins never touch task_session_commits / task_session_git_snapshots.
message SessionCodeStats {
  string session_id = 1;
  int64 lines_added_committed = 2;     // SUM of commit insertions
  int64 lines_deleted_committed = 3;   // SUM of commit deletions
  int64 lines_added_peak_pending = 4;  // peak uncommitted diff additions across snapshots
  int64 lines_deleted_peak_pending = 5;
}
message ListSessionCodeStatsRequest { SessionFilter filter = 1; Page page = 2; }
message ListSessionCodeStatsResponse { repeated SessionCodeStats stats = 1; PageInfo page_info = 2; }

// ── Writes (phase 2; api_write) ──────────────────────────────────────────────
message CreateTaskRequest {
  string workspace_id = 1;
  string workflow_id = 2;
  optional string workflow_step_id = 3;
  string title = 4;
  string description = 5;
  optional string parent_id = 6;
  bool start_agent = 7;
  // kandev stamps source = "plugin:<id>" server-side; not settable here.
}
message CreateTaskResponse { Task task = 1; }
message UpdateTaskRequest {
  string id = 1;
  optional string title = 2;
  optional string description = 3;
  optional string state = 4;
  optional string workflow_step_id = 5;
}
message UpdateTaskResponse { Task task = 1; }
message Comment {
  string id = 1;
  string task_id = 2;
  string body = 3;
  string source = 4;                // "plugin:<id>"
  string created_at = 5;
}
message CreateCommentRequest { string task_id = 1; string body = 2; }
message CreateCommentResponse { Comment comment = 1; }