fix(coding-agent): scope nested .gitignore rules to their subtree in find

The find tool previously collected every .gitignore under the search
path and passed them to fd via --ignore-file. fd treats --ignore-file
entries as a single global ignore source, so rules from a/.gitignore
also filtered files under sibling b/.

Drop the manual collection and pass --no-require-git instead, which
makes fd apply hierarchical .gitignore semantics whether or not a git
repo is present.

closes #3303

packages/coding-agent/test/suite/regressions/3303-find-nested-gitignore.test.ts

@@ -0,0 +1,83 @@
+import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { afterEach, beforeEach, describe, expect, it } from "vitest";
+import { createFindToolDefinition } from "../../../src/core/tools/find.js";
+
+/**
+ * Regression test for https://github.com/badlogic/pi-mono/issues/3303
+ *
+ * The `find` tool previously collected every `.gitignore` under the search
+ * path and passed them to `fd` via `--ignore-file`. fd treats `--ignore-file`
+ * entries as a single global ignore source, so rules from `a/.gitignore`
+ * also filtered files under sibling `b/`. The fix switches to fd's
+ * hierarchical `.gitignore` handling via `--no-require-git` and drops the
+ * manual collection.
+ */
+describe("issue #3303 nested .gitignore rules leak into sibling directories", () => {
+	let tempRoot: string;
+
+	async function runFind(pattern: string): Promise<string[]> {
+		const def = createFindToolDefinition(tempRoot);
+		const ctx = {} as Parameters<typeof def.execute>[4];
+		const result = (await def.execute("call-1", { pattern }, undefined, undefined, ctx)) as {
+			content: Array<{ type: string; text?: string }>;
+		};
+		const text = result.content[0]?.text ?? "";
+		if (text === "No files found matching pattern") return [];
+		return text
+			.split("\n")
+			.map((l) => l.trim())
+			.filter((l) => l.length > 0 && !l.startsWith("["))
+			.sort();
+	}
+
+	afterEach(() => {
+		if (tempRoot) rmSync(tempRoot, { recursive: true, force: true });
+	});
+
+	describe("flat sibling case", () => {
+		beforeEach(() => {
+			tempRoot = mkdtempSync(join(tmpdir(), "pi-3303-flat-"));
+			mkdirSync(join(tempRoot, "a"), { recursive: true });
+			mkdirSync(join(tempRoot, "b"), { recursive: true });
+			writeFileSync(join(tempRoot, "a", ".gitignore"), "ignored.txt\n");
+			writeFileSync(join(tempRoot, "a", "ignored.txt"), "");
+			writeFileSync(join(tempRoot, "a", "kept.txt"), "");
+			writeFileSync(join(tempRoot, "b", "ignored.txt"), "");
+			writeFileSync(join(tempRoot, "b", "kept.txt"), "");
+			writeFileSync(join(tempRoot, "root.txt"), "");
+		});
+
+		it("applies a/.gitignore only inside a/ and leaves b/ untouched", async () => {
+			const files = await runFind("**/*.txt");
+			expect(files).toEqual(["a/kept.txt", "b/ignored.txt", "b/kept.txt", "root.txt"]);
+		});
+	});
+
+	describe("deeply nested case", () => {
+		beforeEach(() => {
+			tempRoot = mkdtempSync(join(tmpdir(), "pi-3303-deep-"));
+			mkdirSync(join(tempRoot, "a", "deep"), { recursive: true });
+			mkdirSync(join(tempRoot, "b"), { recursive: true });
+			writeFileSync(join(tempRoot, "a", ".gitignore"), "ignored.txt\n");
+			writeFileSync(join(tempRoot, "a", "deep", ".gitignore"), "secret.txt\n");
+			writeFileSync(join(tempRoot, "a", "ignored.txt"), "");
+			writeFileSync(join(tempRoot, "a", "kept.txt"), "");
+			writeFileSync(join(tempRoot, "a", "deep", "ignored.txt"), "");
+			writeFileSync(join(tempRoot, "a", "deep", "secret.txt"), "");
+			writeFileSync(join(tempRoot, "a", "deep", "kept.txt"), "");
+			writeFileSync(join(tempRoot, "b", "ignored.txt"), "");
+			writeFileSync(join(tempRoot, "b", "kept.txt"), "");
+			writeFileSync(join(tempRoot, "root.txt"), "");
+		});
+
+		it("scopes each .gitignore to its own subtree", async () => {
+			const files = await runFind("**/*.txt");
+			// a/.gitignore ignores 'ignored.txt' within a/ and a/deep/.
+			// a/deep/.gitignore additionally ignores 'secret.txt' within a/deep/.
+			// b/ is untouched by either.
+			expect(files).toEqual(["a/deep/kept.txt", "a/kept.txt", "b/ignored.txt", "b/kept.txt", "root.txt"]);
+		});
+	});
+});