You are helping me build the following AI agent workflow.

## Goal
Timesheet Generator: Daily at 7 PM, it gathers emails, calendar events, and GitHub activity to generate a clean timesheet in Google Sheets.

## Specification
- What it does: You get a clean timesheet in Google Sheets every day at 7 PM by automatically pulling your emails, calendar events, and GitHub activity. The agent filters out noise like newsletters or irrelevant commits before using an AI to summarize each item for easy billing and reporting.
- Trigger: On a schedule (Scheduled · daily 7 PM)
- Autonomy: Fully hands-off
- Expected setup effort: under an hour
- Tools/services involved:
  - n8n: Workflow orchestration platform
  - Gmail: Collecting email activity data
  - Google Calendar: Logging meeting events and duration
  - GitHub: Tracking commits and pull requests
  - OpenAI: Generating concise activity summaries

## Known pitfalls, handle each one explicitly in your implementation
1. LLM token costs can accumulate quickly with large volumes of emails, so limit the input text length before sending it to the model.
2. Google Sheets writes can fail silently if the sheet permissions are incorrect, so verify service account access rights beforehand.

## Reference implementation
https://n8n.io/workflows/5396 (workflow template)
Fetch and inspect this before building. If it matches my stack, adapt it;
if not, rebuild the pattern with my tools.

## Process requirements
1. Before building: ask me which of the listed tools I actually use and
   what my platform is (n8n / Make / code / other). Do not assume.
2. Adapt the pattern to my answers; do not force the reference stack.
3. Address every pitfall above; tell me how you handled each.
4. Provide a test plan I can run before letting this touch real data.
5. Ask before any step that sends messages, modifies data, or spends money.

Source: https://usecasesforagents.com/use-case/automated-timesheet-generator/ via usecasesforagents.com