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|
import type { TSchema, Static } from "typebox";
import type {
AgentToolResult,
AgentToolUpdateCallback,
ExtensionAPI,
ExtensionContext,
Theme,
ToolDefinition,
ToolRenderResultOptions,
} from "@mariozechner/pi-coding-agent";
import type { Component } from "@mariozechner/pi-tui";
import type { BrowserClient } from "../client";
import type { Result } from "./result";
export type ToolOk = {
readonly text: string;
readonly details?: Readonly<Record<string, unknown>>;
};
export type ToolErrKind =
| "not_connected"
| "cdp_error"
| "timeout"
| "invalid_state"
| "io_error"
| "internal";
export type ToolErr = {
readonly kind: ToolErrKind;
readonly message: string;
readonly details?: Readonly<Record<string, unknown>>;
};
export type HandlerContext = {
readonly client: BrowserClient;
readonly signal: AbortSignal | undefined;
readonly onUpdate: (update: ToolOk) => void;
readonly extensionCtx: ExtensionContext;
};
export type ToolHandler<S extends TSchema> = (
args: Static<S>,
ctx: HandlerContext,
) => Promise<Result<ToolOk, ToolErr>>;
export type BrowserToolDefinition<S extends TSchema> = {
readonly name: string;
readonly label: string;
readonly description: string;
readonly promptSnippet: string;
readonly promptGuidelines: ReadonlyArray<string>;
readonly parameters: S;
readonly handler: ToolHandler<S>;
readonly renderCall?: (args: Static<S>, theme: Theme) => Component;
readonly renderResult?: (result: AgentToolResult<unknown>, expanded: boolean, theme: Theme) => Component;
/** If true, the tool acquires the client's mutation mutex before executing.
* This ensures that two serialized tools never run concurrently,
* preventing race conditions on shared CDP session/page state. */
readonly serialized?: boolean;
readonly ensureAlive?: boolean;
};
// Type-erased entry for the registry's heterogeneous TOOLS array.
// renderCall accepts `never` so any concrete args type satisfies it via
// function-parameter contravariance (a handler that takes SpecificT is
// assignable to one that takes never, because never is a subtype of everything).
export type AnyBrowserToolDefinition = Omit<BrowserToolDefinition<TSchema>, "renderCall" | "renderResult"> & {
readonly renderCall?: (args: never, theme: Theme) => Component;
readonly renderResult?: (result: AgentToolResult<unknown>, expanded: boolean, theme: Theme) => Component;
};
export const defineBrowserTool = <S extends TSchema>(
def: BrowserToolDefinition<S>,
): BrowserToolDefinition<S> => def;
type OkDetails = { readonly ok: true } & Readonly<Record<string, unknown>>;
type ErrDetails = { readonly ok: false; readonly kind: ToolErrKind; readonly message: string } & Readonly<Record<string, unknown>>;
const toToolResult = (
r: Result<ToolOk, ToolErr>,
toolName: string,
): AgentToolResult<OkDetails | ErrDetails> => {
if (r.success) {
const details: OkDetails = { ok: true, ...(r.data.details ?? {}) };
return {
content: [{ type: "text", text: r.data.text }],
details,
};
}
const details: ErrDetails = {
ok: false,
kind: r.error.kind,
message: r.error.message,
...(r.error.details ?? {}),
};
return {
// isError is an extension the pi-coding-agent runtime picks up from the result object;
// AgentToolResult<T> itself doesn't declare it but the runtime reads it via duck-typing.
// We cast through unknown to avoid widening the return type.
...(({ isError: true }) as unknown as object),
content: [{ type: "text", text: `${toolName} failed (${r.error.kind}): ${r.error.message}` }],
details,
};
};
export const registerBrowserTool = (
pi: ExtensionAPI,
client: BrowserClient,
def: AnyBrowserToolDefinition,
): void => {
// AnyBrowserToolDefinition is type-erased; we recover the schema-typed surface
// by casting def to the generic form. The cast is safe because defineBrowserTool
// ensures the handler, parameters, and renderCall were all created with the same S.
type S = TSchema;
const td: ToolDefinition<S> = {
name: def.name,
label: def.label,
description: def.description,
promptSnippet: def.promptSnippet,
promptGuidelines: [...def.promptGuidelines],
parameters: def.parameters,
...(def.renderCall
? {
renderCall: (args: Static<S>, theme: Theme, _ctx: Parameters<NonNullable<ToolDefinition<S>["renderCall"]>>[2]) =>
// Non-null assertion safe: this branch only runs when renderCall was provided.
// Cast from never->Component to unknown->Component: safe because at runtime
// args is always the concrete Static<S> value the tool was defined with.
(def.renderCall as (args: unknown, theme: Theme) => Component)(args, theme),
}
: {}),
...(def.renderResult
? {
renderResult: (
result: AgentToolResult<unknown>,
options: ToolRenderResultOptions,
theme: Theme,
_ctx: Parameters<NonNullable<ToolDefinition<S>["renderResult"]>>[3],
) =>
// Non-null assertion safe: this branch only runs when renderResult was provided.
def.renderResult!(result, options.expanded ?? false, theme),
}
: {}),
async execute(_toolCallId, args, signal, onUpdate, extensionCtx) {
if (def.ensureAlive !== false) {
const alive = await client.ensureAlive();
if (!alive.success) {
return toToolResult(
{ success: false, error: { kind: "not_connected", message: alive.error.message } },
def.name,
);
}
}
// Serialized tools acquire the client's mutation mutex so that only one
// mutation tool runs at a time. Observation tools skip this and run freely
// in parallel. AbortSignal is checked after acquiring the lock so that a
// cancelled task doesn't hold the mutex forever.
let release: (() => void) | undefined;
if (def.serialized) {
const acquire = await client.mutationMutex().acquire();
release = acquire;
if (signal?.aborted) {
release();
return toToolResult(
{ success: false, error: { kind: "invalid_state", message: "Tool execution aborted before entering serialized lane" } },
def.name,
);
}
}
try {
const result = await def.handler(args, {
client,
signal,
onUpdate: (u) => {
if (onUpdate) {
// AgentToolUpdateCallback expects AgentToolResult<TDetails>; we use unknown for TDetails.
const update: AgentToolResult<OkDetails> = {
content: [{ type: "text", text: u.text }],
details: { ok: true, ...(u.details ?? {}) },
};
// Cast needed: onUpdate is AgentToolUpdateCallback<unknown> (generic TDetails).
(onUpdate as AgentToolUpdateCallback<OkDetails>)(update);
}
},
extensionCtx,
});
return toToolResult(result, def.name);
} finally {
release?.();
}
},
};
pi.registerTool(td);
};
|
