/**
* Model context updates — sends page/selection info to the MCP host.
*/
import type { App } from "@modelcontextprotocol/ext-apps";
import type { TextLine } from "./types";
export interface ContextState {
app: App;
pageIndex: number;
totalPages: number;
pageMetadata: string;
getTextLines: () => TextLine[];
searchTerm?: string;
searchMatchCount?: number;
}
let timer: ReturnType<typeof setTimeout> | null = null;
let lastSentContext = "";
export function scheduleContextUpdate(state: ContextState, selectedLine?: TextLine) {
if (timer) clearTimeout(timer);
const delay = selectedLine ? 0 : 500;
timer = setTimeout(() => sendContextUpdate(state, selectedLine), delay);
}
async function sendContextUpdate(state: ContextState, selectedLine?: TextLine) {
const { app, pageIndex, totalPages, pageMetadata } = state;
if (!app) return;
const caps = app.getHostCapabilities();
if (!caps?.updateModelContext) return;
const page = pageIndex + 1;
const lines = state.getTextLines();
const fullText = lines.map(l => `[${l.id}] ${l.transcription}`).join("\n");
const parts = [`Document viewer: page ${page}/${totalPages} (page_index=${pageIndex})`];
if (pageMetadata) parts.push(`Page metadata: ${pageMetadata}`);
if (selectedLine) parts.push(`User selected text (${selectedLine.id}): "${selectedLine.transcription}"`);
if (state.searchTerm) parts.push(`Active search: "${state.searchTerm}" (${state.searchMatchCount ?? 0} matches on this page)`);
parts.push(fullText ? `Page transcription (line IDs for highlight-region tool):\n${fullText}` : "(no transcribed text on this page)");
const text = parts.join("\n");
if (text === lastSentContext) return;
lastSentContext = text;
try {
await app.updateModelContext({
content: [{ type: "text", text }],
});
} catch (e) {
console.error("[updateModelContext]", e);
}
}
/** Reset dedup state (e.g. when the component unmounts / remounts) */
export function resetContextState() {
if (timer) clearTimeout(timer);
timer = null;
lastSentContext = "";
}
