feat(tool-youtube-transcript): write full transcript to /tmp/dispatch on truncation

When the formatted transcript exceeds the 50K char output cap, the tool now
writes the full output to /tmp/dispatch/{video_id}.txt and returns the
truncated output with a notice pointing to the file path. The writeFile dep
is injectable so tests verify without touching the filesystem.

1 files changed, 7 insertions, 0 deletions

diff --git a/packages/tool-youtube-transcript/src/format.test.ts b/packages/tool-youtube-transcript/src/format.test.ts
index 7555318..79832da 100644
--- a/packages/tool-youtube-transcript/src/format.test.ts
+++ b/packages/tool-youtube-transcript/src/format.test.ts
@@ -116,4 +116,11 @@ describe("truncateOutput", () => {
 		expect(truncateOutput("short", 100)).toBe("short");
 		expect(truncateOutput("exact", 5)).toBe("exact");
 	});
+
+	it("includes save path in notice when provided", () => {
+		const output = "a".repeat(100);
+		const result = truncateOutput(output, 50, "/tmp/dispatch/vid123.txt");
+		expect(result).toContain("/tmp/dispatch/vid123.txt");
+		expect(result).toContain("use read_file to access it");
+	});
 });