diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index f70052c..b066dca 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -17,8 +17,7 @@ Thanks for adding to the Speechify Cookbook! The full, authoritative checklist l
 3. Read the language guide:
    [`typescript-recipes.md`](./agents/typescript-recipes.md) or
    [`python-recipes.md`](./agents/python-recipes.md), and the API reference
-   [`speechify-tts.md`](./agents/speechify-tts.md) /
-   [`voice-agents.md`](./agents/voice-agents.md).
+   [`speechify-tts.md`](./agents/speechify-tts.md).
 4. Write the recipe + a README following the fixed template.
 5. Update [`README.md`](./README.md) and [`COVERAGE.md`](./COVERAGE.md).
 6. Run `pnpm format`, then verify the recipe runs from a clean state.
diff --git a/agents/maintenance.md b/agents/maintenance.md
index 54ba028..b8b17f8 100644
--- a/agents/maintenance.md
+++ b/agents/maintenance.md
@@ -28,5 +28,5 @@ Keeping the cookbook consistent as it grows.
 
 The Speechify API evolves. Before trusting a method name or response field, check the
 installed SDK or the live docs (`https://docs.speechify.ai/llms.txt` is a good index). If
-reality differs from the notes in `agents/speechify-tts.md` or `agents/voice-agents.md`,
+reality differs from the notes in `agents/speechify-tts.md`,
 trust the API and update those files in the same change.
diff --git a/agents/monorepo.md b/agents/monorepo.md
index fb42510..b0ed436 100644
--- a/agents/monorepo.md
+++ b/agents/monorepo.md
@@ -46,7 +46,7 @@ speechify-cookbook/
 
 | Folder   | What                                        | Status                                  |
 | -------- | ------------------------------------------- | --------------------------------------- |
-| `audio/` | Text-to-Speech, plus future audio products. | Active. TypeScript + Python on v2 SDKs. |
+| `audio/` | Text-to-Speech, plus future audio products. | Active. TypeScript + Python on v4 SDKs. |
 
 ## Languages and tooling
 
diff --git a/agents/speechify-tts.md b/agents/speechify-tts.md
index b7c5f3e..a0ee7b8 100644
--- a/agents/speechify-tts.md
+++ b/agents/speechify-tts.md
@@ -15,7 +15,7 @@ Both SDKs read `SPEECHIFY_API_KEY` from the environment. The deprecated
 
 ## Synthesize speech
 
-**TypeScript** (`@speechify/api` v3)
+**TypeScript** (`@speechify/api` v4)
 
 ```ts
 import { SpeechifyClient } from "@speechify/api";
@@ -34,7 +34,7 @@ import fs from "node:fs";
 fs.writeFileSync("output.mp3", Buffer.from(response.audio_data, "base64"));
 ```
 
-**Python** (`speechify-api` v3)
+**Python** (`speechify-api` v4)
 
 ```python
 from speechify import Speechify
@@ -60,12 +60,12 @@ with open("output.mp3", "wb") as f:
 
 ## Parameters
 
-| Param          | Notes                                                                                                                               |
-| -------------- | ----------------------------------------------------------------------------------------------------------------------------------- |
-| `input`        | Text (or SSML) to synthesize. Up to ~20,000 characters per request.                                                                 |
-| `voice_id`     | A voice identifier, e.g. `geffen_32`.                                                                                               |
-| `model`        | `simba-3.2` (English, lowest latency) or `simba-3.0` (multilingual: English plus German, Spanish, French, Italian, and Portuguese). |
-| `audio_format` | `mp3`, `wav`, `ogg`, `aac`, …                                                                                                       |
+| Param          | Notes                                                                                                                                                                                                 |
+| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| `input`        | Text (or SSML) to synthesize. Limits are per endpoint: 2,000 characters for `audio.speech`, 20,000 for `audio.stream` / `audio.stream_with_timestamps` (<https://docs.speechify.ai/docs/api-limits>). |
+| `voice_id`     | A voice identifier, e.g. `geffen_32`.                                                                                                                                                                 |
+| `model`        | `simba-3.2` (English, lowest latency) or `simba-3.0` (multilingual: English plus German, Spanish, French, Italian, and Portuguese).                                                                   |
+| `audio_format` | `mp3`, `wav`, `ogg`, `aac`, …                                                                                                                                                                         |
 
 ## Capabilities to build recipes around
 
diff --git a/recipes/audio/typescript/sdk/quickstart/README.md b/recipes/audio/typescript/sdk/quickstart/README.md
index f225fde..af0ba60 100644
--- a/recipes/audio/typescript/sdk/quickstart/README.md
+++ b/recipes/audio/typescript/sdk/quickstart/README.md
@@ -25,6 +25,6 @@ You'll get an `output.mp3` in this folder.
 ## What it does
 
 - Creates a `SpeechifyClient` with your API key.
-- Calls `client.audio.speech(...)` with `input`, `voiceId`, `audioFormat`, and `model`
+- Calls `client.audio.speech(...)` with `input`, `voice_id`, `audio_format`, and `model`
   (`simba-3.2` for English, lowest latency; `simba-3.0` for multilingual — English plus German, Spanish, French, Italian, and Portuguese).
 - Decodes the base64 `response.audio_data` and writes it to disk.
diff --git a/recipes/audio/typescript/sdk/speech-marks/src/index.ts b/recipes/audio/typescript/sdk/speech-marks/src/index.ts
index 799e897..d45e4fc 100644
--- a/recipes/audio/typescript/sdk/speech-marks/src/index.ts
+++ b/recipes/audio/typescript/sdk/speech-marks/src/index.ts
@@ -28,7 +28,7 @@ async function main() {
 
   fs.writeFileSync("output.mp3", Buffer.from(response.audio_data, "base64"));
 
-  // `speechMarks.chunks` holds one entry per word, with start/end times in the audio.
+  // `speech_marks.chunks` holds one entry per word, with start/end times in the audio.
   const words = response.speech_marks.chunks;
 
   // Build a WebVTT file with one cue per word — the basis for karaoke-style highlighting.