chenhg5/cc-connect · info

gemini stt: marshal request: %w

Error message

gemini stt: marshal request: %w

What it means

Thrown by GeminiSTT.Transcribe in core/speech.go when json.Marshal fails while serializing the Gemini generateContent request body. json.Marshal on a plain anonymous struct built from strings/bytes essentially never fails in practice, so this error indicates an extraordinary serialization failure (e.g. unsupported value introduced by future code changes).

Source

Thrown at core/speech.go:254

			{
				"parts": []map[string]any{
					{
						"inline_data": map[string]any{
							"mime_type": mime,
							"data":      b64,
						},
					},
					{
						"text": prompt,
					},
				},
			},
		},
	}

	jsonData, err := json.Marshal(reqBody)
	if err != nil {
		return "", fmt.Errorf("gemini stt: marshal request: %w", err)
	}

	apiURL := fmt.Sprintf("%s/models/%s:generateContent", g.BaseURL, url.PathEscape(g.Model))
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, apiURL, bytes.NewReader(jsonData))
	if err != nil {
		return "", fmt.Errorf("gemini stt: create request: %w", err)
	}
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("x-goog-api-key", g.APIKey)

	resp, err := g.Client.Do(req)
	if err != nil {
		return "", fmt.Errorf("gemini stt: request: %w", err)
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(resp.Body)
	if err != nil {

View on GitHub (pinned to 4000b2338a)

Solutions

1. If it occurs, inspect the wrapped json error naming the offending field/type.
2. Review recent changes to the reqBody struct in GeminiSTT.Transcribe for unmarshalable types (chan, func, cycles).
3. Replace unsupported fields with marshalable equivalents ([]byte, string, etc.).

Example fix

// before
InlineData{MIMEType: "audio/mp3", Data: ch} // ch is a channel: unmarshalable
// after
InlineData{MIMEType: "audio/mp3", Data: audioBytes} // []byte, marshalable

text, err := stt.Transcribe(ctx, audio)
if err != nil {
    if strings.Contains(err.Error(), "marshal request") {
        slog.Error("gemini stt: request serialization failed", "err", err)
        return "", err // genuine bug: fail fast
    }
    return err
}

When it happens

Trigger: json.Marshal(reqBody) returns an error — practically only if reqBody ever contains a value that cannot be marshaled (channel, func, cyclic reference) after future modifications; not reachable with the current fixed struct.

Common situations: Essentially never hit by users of the current code; would surface only after a developer adds a field with an unmarshalable type to the Gemini request struct.

Understand the failure class

Background: json.Marshal / "failed to marshal" errors in Go: why "unsupported type" happens and how to fix it — this error's family across 22 libraries.

Related errors

• gemini stt: parse response: %w
• marshal: %w
• codex app-server encode: %w
• marshal: %w
• piSession: marshal command: %w

AI-assisted analysis of chenhg5/cc-connect@4000b2338a (2026-09-06). Data as JSON: /api/errors/f0a02f047389af87. Report an issue: GitHub.