`@livekit/agents-plugin-deepgram` double-URL-encodes streaming params

[ubinatus]

Describe the bug

Summary

The Deepgram STT plugin calls encodeURIComponent(v) on each query param value before passing it to URLSearchParams.append(). URLSearchParams.append() already URL-encodes its inputs, so the value is encoded twice on the wire. Any param containing characters that encodeURIComponent rewrites (space, ', &, %, non-ASCII, etc.) is corrupted by the time it reaches Deepgram.

Object.entries(params).forEach(([k, v]) => {
  if (v !== void 0) {
    if (typeof v === "string" || typeof v === "number" || typeof v === "boolean") {
      streamURL.searchParams.append(k, encodeURIComponent(v));        // ← double-encodes
    } else {
      v.forEach((x) => streamURL.searchParams.append(k, encodeURIComponent(x))); // ← double-encodes
    }
  }
});

Where it bites in practice

The most common trigger is keyterm (and keywords), which accept user-supplied free-text vocabulary like "Joe's Plumbing", "AT&T", or "café". Example:

• Input: keyterm: ["Joe's Plumbing"]
• After encodeURIComponent: "Joe%27s%20Plumbing"
• After URLSearchParams re-encodes the %: wire param keyterm=Joe%2527s%2520Plumbing
• Deepgram decodes that to the literal string Joe%27s%20Plumbing — the keyterm is effectively broken and provides no recognition boost.

The same applies to any string param containing reserved chars. Booleans/numbers and ASCII-only strings ("nova-3", "en") happen to round-trip cleanly, which is why the bug went unnoticed for plain configs.

Expected behavior

Each param should be URL-encoded exactly once. URLSearchParams.append(k, v) already does the right thing — the wrapping encodeURIComponent should be removed.

Proposed fix

       Object.entries(params).forEach(([k, v]) => {
         if (v !== void 0) {
           if (typeof v === "string" || typeof v === "number" || typeof v === "boolean") {
-            streamURL.searchParams.append(k, encodeURIComponent(v));
+            streamURL.searchParams.append(k, String(v));
           } else {
-            v.forEach((x) => streamURL.searchParams.append(k, encodeURIComponent(x)));
+            v.forEach((x) => streamURL.searchParams.append(k, String(x)));
           }
         }
       });

(Booleans/numbers need String(...) because URLSearchParams.append types its second arg as string; current code coincidentally stringifies via encodeURIComponent.)

Relevant log output

No response

Describe your environment

System:
OS: macOS 26.3
CPU: (16) arm64 Apple M4 Max
Memory: 27.75 GB / 128.00 GB
Shell: 5.9 - /bin/zsh
Binaries:
Node: 24.14.1 - /opt/homebrew/opt/node@24/bin/node
npm: 11.11.0 - /opt/homebrew/opt/node@24/bin/npm
pnpm: 10.33.0 - /opt/homebrew/bin/pnpm
bun: 1.2.4 - /Users/juanandrescastro/.bun/bin/bun

Minimal reproducible example

Repro

import * as deepgram from "@livekit/agents-plugin-deepgram";

const stt = new deepgram.STT({
  model: "nova-3",
  language: "en",
  keyterm: ["Joe's Plumbing", "AT&T", "café"],
});
// Capture the WS URL the plugin opens — the keyterm values arrive as
// keyterm=Joe%2527s%2520Plumbing&keyterm=AT%2526T&keyterm=caf%25C3%25A9
// instead of the correctly-single-encoded form.

Additional information

Workarounds for downstreams (until fix lands)

None clean. Pre-transforming values from user code can't cancel both layers, sanitizing values to ASCII is lossy for the use case, and switching keyterm→keywords hits the identical code path. Maintaining an npm/pnpm patch is currently the only viable mitigation.