Privacy-Safe WebContainer Diagnostic Bundle

Overview

This skill defines or implements a bounded diagnostic artifact for WebContainer problems. The bundle records state and outcomes, not arbitrary source, environment values, complete terminal output, browser history, cookies, or credential material.

Prerequisites

• A named incident or reproducible failure and an approved output location
• Agreement on who may receive the bundle and how long it may be retained
• Permission to inspect the relevant host configuration and bounded runtime evidence

Tool Discipline

Use Read, Glob, and Grep to locate existing logging, header, boot, event, and process instrumentation. Use WebFetch only for current official StackBlitz or WebContainers documentation. Use Write for a new approved bundle schema or artifact and Edit for narrow instrumentation changes.

Current Contract

• Record a schema version, capture time, application release, package versions, coarse browser family/version, secure-context state, and crossOriginIsolated boolean.
• Record the presence and normalized values of relevant response headers without unrelated headers or cookies.
• Record lifecycle transitions, event names, process command identity, exit code, duration, and a bounded/redacted output tail.
• Record only filesystem counts and tested synthetic paths; do not enumerate or copy user file contents.
• Record resource symptoms such as out-of-memory errors without inventing a universal numeric memory quota.
• Make every redaction and omitted evidence class visible in the bundle metadata.

Authentication

Never include API-key values, OAuth parameters, registry credentials, cookies, URLs carrying tokens, .env content, private package metadata beyond the minimum identity, or full user-agent/client fingerprint data. Record auth state as a coarse enum when relevant.

Workflow

1. Define the incident ID, audience, retention, schema, byte cap, and redaction rules.
2. Collect static package and hosting configuration from repository evidence.
3. Collect browser capability, served-header, and lifecycle state from the failing session.
4. Add bounded event and process evidence, preserving exit codes and timestamps.
5. Apply automatic redaction, then perform a human review before sharing.
6. Reproduce once with a synthetic fixture and attach the bundle hash plus collection limitations.

Approval Boundaries

Require explicit authorization before adding runtime telemetry, persisting a bundle, collecting user-session evidence, or sending the artifact outside the approved audience. A human must review the final bytes before external disclosure.

Output

Return the schema and bundle path, SHA-256 digest, byte count, collected and omitted fields, redaction result, reproduction link or command, audience/retention, and unresolved evidence gaps.

Error Handling

Examples

For an intermittent boot failure, create a JSON bundle containing package versions, header values, lifecycle transitions, event names, one process exit record, redaction metadata, and a digest—without source files or secret values.

Resources

• Official StackBlitz and WebContainers references
• WebContainer API events
• WebContainers troubleshooting