EXP-01 - Exploratory Session - Background Fetch Before Filter

Date: 2025-09-18
Build/Commit: 6a951eb (docs/baseline branch)
Environment: melodx.io (Prod), Firefox (desktop)

Charter:
Investigate default load behavior of /rank to confirm whether background song fetching starts before user applies filters.

Setup

• Account: Main (Google login)
• Observed initial page load and network activity before filter submission.
• Console open to track repeated API calls.

Heuristics

• State-model tour — verify state transitions (idle → filter apply → song fetch)
• User-intention oracle — confirm system waits for explicit input

Notes & Findings

• /rank triggers background fetch immediately using default filter values (pop / all / all).
• Multiple fetch cycles occur before Apply is pressed.
• Console repeatedly logs: “Triggering background fetch for more songs.”
• ~13–15 songs loaded per cycle; occasional DOMException: The operation was aborted.
• userContext resolves mid-sequence, causing further fetches.

Evidence

• Screenshots: reports/screenshots/exp01-autofetch.png
• Logs: logs/exp01-autofetch.txt

Bugs

• DEF-003 — Background fetch before filter apply
  Impact: Unnecessary network traffic and irrelevant song buffer.
  Expected: Idle until user applies filters.
  Severity: Major
  Status: Resolved
  Report: DEF-003 PR: #4 - fix: DEF-003

Learned

• SongProvider tied to mount lifecycle, not filter submission.
• Default filters act as implicit “Apply,” creating fetch loops.

Risks

• Excess backend/API load from redundant requests.
• Users may see irrelevant content, confusing UX.
• Timeouts and console errors may reduce trust.

Outcome

• Status: Completed
• Follow-ups:
• Gate SongProvider fetch until filters are explicitly applied.
• Add regression: /rank remains idle until user triggers fetch.