Upload Assets to Stitch Project

v20260604

stitch-upload-to-stitch

This skill provides a robust method for uploading local digital assets, including images, mockups, and full HTML files, to a Stitch project. It bypasses the limitations of standard tool calls by streaming files directly over HTTP, ensuring that large visual assets or complex web pages can be processed accurately for your design and prototyping workflow. Ideal for integrating local design iterations into cloud-based prototypes.

Stitch Assets Upload HTML Mockups

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Overview

Upload-to-Stitch

Upload local assets (images, mockups, HTML files) to a Stitch project using the provided upload script, which bypasses the MCP tool's base64 output token limits.

[!NOTE] The AI model cannot upload files via MCP tools directly because the base64 encoding of even a small file exceeds the model's output token limit (~16K tokens). This script reads the file and sends it directly over HTTP.

Steps

1. Identify Target Project

Use list_projects to find the correct projectId.

2. Get the API Key

Locate your active MCP server configuration file and extract the API key:

Antigravity: .gemini/antigravity/mcp_config.json or .gemini/jetski/mcp_config.json
Gemini CLI: ~/.gemini/settings.json or ~/.gemini/extensions/Stitch/gemini-extension.json
Claude Code: ~/.claude.json

Extract:

API Key: From the X-Goog-Api-Key header or auth argument
MCP URL (optional): From the httpUrl or endpoint argument (defaults to https://stitch.googleapis.com)

[!IMPORTANT] If you cannot find the API key in any of these locations, or if you cannot access these files, you MUST ask the user to provide the Stitch API key. Do not proceed without a valid API key.

3. Run Upload Script

[!WARNING] Checkpoint — User Confirmation Required. Before running the upload script, you MUST pause and present the file(s) to be uploaded (paths, sizes, and types) to the user and wait for explicit approval. Do NOT execute the upload script until the user confirms.

Use run_command to execute the Python script:

python3 <SKILL_DIR>/scripts/upload_to_stitch.py \
  --project-id <PROJECT_ID> \
  --file-path <PATH_TO_FILE> \
  --api-key <API_KEY> \
  [--api-url <STITCH_API_URL>] \
  [--title <SCREEN_TITLE>]

[!TIP] macOS / SSL Certificate Troubleshooting: If the upload fails with ssl.SSLCertVerificationError: [SSL: CERTIFICATE_VERIFY_FAILED] unable to get local issuer certificate, this means your Python installation does not have root certificate authorities configured. Fix it by prepending SSL_CERT_FILE using the certifi bundle:
SSL_CERT_FILE=$(python3 -c "import certifi; print(certifi.where())") python3 <SKILL_DIR>/scripts/upload_to_stitch.py \
  --project-id <PROJECT_ID> \
  --file-path <PATH_TO_FILE> \
  --api-key <API_KEY>

Supported File Types

Extension	MIME Type
`.png`	`image/png`
`.jpg`, `.jpeg`	`image/jpeg`
`.webp`	`image/webp`
`.html`, `.htm`	`text/html`

The script auto-detects MIME type from the file extension.

Script Defaults

--api-url defaults to https://stitch.googleapis.com
--api-key is required
Screen instances are automatically created for display
For HTML files, screenType is set to DOCUMENT; for images, IMAGE

Info

Category Development

Name stitch-upload-to-stitch

Version v20260604

Size 4.32KB

Source google-labs-code/stitch-skills

Updated At 2026-06-10