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Build Log – 2025-12-09

Build Log – 2025-12-09

📅 Daily Log — 2025-12-09

🧠 Context / Focus for Today

  • Continue hardening the Garmin activity sync pipeline.
  • Reduce production errors and make historical imports reliable.
  • Organize the development workflow with Cursor, GitHub, and Vercel.
  • Clarify crons, pull-token logic, and planning board tasks.

✔️ Things I Got Done Today

🏃‍♂️ Product / Training

  • Thought through triathlon cadence strategy with a friend's coach's advice.
  • Analyzed how moderately high cadence on the bike (vs grinding big gears) can protect the run legs and pacing.

💻 Flow State Codebase

  • Deep-dived Garmin API behavior for historical activity fetch.
  • Improved handling of InvalidPullTokenException in lib/garmin/fetch-activities.ts so that when a stored pull token fails:
    • The app logs the issue and invalidates the token in the database.
    • It retries the same time range without the token.
    • It only surfaces a configuration error if the retry also fails.
  • Ran build/lint fixes and continued working through Next.js upgrade fallout and hydration-related behavior.

🐛 Debugging / Fixes

  • Investigated Garmin sync failures using detailed Vercel logs.
  • Saw repeated warnings about missing authentication headers on Garmin webhooks.
  • Refined understanding of:
    • Garmin's Ping/Pull model.
    • Time-range limits.
    • Why invalid or stale pull tokens break historical imports.
  • Clarified that recent-activity sync and historical imports behave differently in the Garmin ecosystem.

🧱 Architecture / Planning

  • Worked through multiple planning board tasks related to Garmin and FIT export.
  • Clarified the intent of debug endpoints such as /api/debug/garmin/webhook-test and /api/debug/planning/*.
  • Identified FIT export as the next major feature once Garmin reliability is "good enough."
  • Started mentally scoping:
    • Unified RUN/BIKE workout schema.
    • How FIT export will plug into the calendar and training engine.
    • Test strategy with real .fit files.

⚙️ DevOps / Tooling

  • Looked into Vercel cron job limits and pricing, and which jobs are actually needed right now.
  • Thought through which cron jobs are "MVP critical" vs "future nice-to-have."
  • Practiced branching, committing, and pushing changes via the CLI (especially when multiple agents made edits).
  • Considered an ideal flow across ChatGPT + Cursor + GitHub + Vercel for Flow State.

🧩 Misc

  • Looked at how to access the project from Cursor on another laptop.
  • Got a clearer mental model for SSH and why tools like Cursor rely on it.
  • Reflected on how to keep AI agents from generating huge diffs by tightening prompts and scoping.

🚧 In Progress

  • Garmin webhook authentication robustness and logging.
  • FIT workout export scoping and preparing example .fit files for tests.
  • Cleaning up planning board tasks related to Garmin and FIT reliability.
  • Reducing UI "skeleton flash" during navigation and loading.

🎯 Targets for Tomorrow

  1. Finish stabilizing Garmin date-range chunking and dedupe behavior.
  2. Kick off the FIT Export implementation with a new Cursor thread and a concrete schema.
  3. Add a /blog route and publish the first daily logs as a running build journal.

🤔 Notes / Observations

  • Debugging Garmin is intricate, but each pass makes the mental model clearer.
  • Good logs (Vercel + structured error handling) dramatically speed up iteration.
  • Cursor is powerful but needs guardrails—prompt clarity matters a lot.
  • The project feels big but less "foggy"; the roadmap and dependencies are sharpening.

📈 Momentum Score (0–10)

7/10 — Solid progress on foundational plumbing. Tomorrow's work on FIT export and /blog should make things feel even more tangible.