feat: file system access, behind a path policy and an approval (#25)

src/lib/hooks/useChat.ts

@@ -1,6 +1,9 @@
 import { useCallback, useEffect, useRef, useState } from "react";
+import { environment } from "@vicinae/api";
 import { runAgent } from "../agent";
+import { confirmWithAlert, createApprovalLedger } from "../approval";
 import { toStoredAttachment } from "../attachments";
+import { createPolicy, displayPath } from "../files";
 import { ipPlace } from "../geo";
 import { buildMessages, composeSystemPrompt } from "../history";
 import { isSelfHosted } from "../ollama";
@@ -205,6 +208,18 @@ export function useChat(options: UseChatOptions): UseChat {
       const controller = new AbortController();
       abortRef.current = controller;
 
+      // Built per turn rather than per session: the ledger inside it is the record of
+      // what the user approved while answering this one question, and the next question
+      // starts by asking again. The policy is cheap to rebuild and holds no state.
+      const policy = createPolicy({
+        supportPath: environment.supportPath,
+        readRoots: preferences.extraReadRoots,
+        writeRoots: preferences.extraWriteRoots,
+      });
+      const fileAccess = preferences.fileEnabled
+        ? { policy, approve: createApprovalLedger(confirmWithAlert).approve }
+        : undefined;
+
       const messages = buildMessages(
         composeSystemPrompt(preferences.systemPrompt, {
           model: preferences.model,
@@ -212,6 +227,11 @@ export function useChat(options: UseChatOptions): UseChat {
           selfHosted: isSelfHosted(preferences.host),
           webTools: preferences.webEnabled,
           vision: visionRef.current,
+          fileTools: preferences.fileEnabled,
+          fileRoots: {
+            read: policy.readRoots.map((root) => displayPath(root, policy.home)),
+            write: policy.writeRoots.map((root) => displayPath(root, policy.home)),
+          },
         }),
         base.turns,
         prompt,
@@ -233,7 +253,10 @@ export function useChat(options: UseChatOptions): UseChat {
             // cap, so the two conventions meet here.
             maxToolRounds: preferences.maxToolRounds ?? null,
             messages,
-            tools: toolsFor({ webEnabled: preferences.webEnabled }),
+            tools: toolsFor({
+              webEnabled: preferences.webEnabled,
+              fileEnabled: preferences.fileEnabled,
+            }),
             toolContext: {
               host: preferences.host,
               apiKey: preferences.apiKey,
@@ -241,6 +264,7 @@ export function useChat(options: UseChatOptions): UseChat {
               // Only wired up when the user switched it on, so an off setting
               // cannot reach the network for a location at all.
               ipPlace: preferences.ipGeolocation ? ipPlace : undefined,
+              files: fileAccess,
             },
             signal: controller.signal,
             events: {