Skip to content

SLOT_TIMER_BUG.md

Latest commit

 

History

History
87 lines (59 loc) · 3.89 KB

SLOT_TIMER_BUG.md

File metadata and controls

87 lines (59 loc) · 3.89 KB

slotTimers Bug: Silent Trade Recording Failure

Summary

An empty slotTimers array in the Flipping Utilities account JSON file causes the plugin to throw IndexOutOfBoundsException on every GE offer event, silently dropping all real-time trades. The plugin appears functional (UI loads, GE History imports work) but records zero live trades.

Discovery

Date: March 14, 2026

Symptom: Only certain items appeared in FU history despite active trading. Investigation of Knife Lord.json revealed:

  • Last real-time offer (slot >= 0): February 26, 2026
  • GE History Tab imports (slot -1) continued working normally
  • 9 IndexOutOfBoundsException errors in client.log per session

Root Cause

The Bug

NewOfferEventPipelineHandler.screenOfferEvent() (lines 134, 152, 163) calls:

slotActivityTimers.get(newOfferEvent.getSlot())

This retrieves a List<SlotActivityTimer> from AccountData.getSlotTimers() and indexes into it using the GE slot number (0-7). If the list is empty, any .get() call throws IndexOutOfBoundsException, which is uncaught — the entire offer event is silently dropped by RuneLite's EventBus.

The same bug exists in FlippingPlugin.setWidgetsOnSlotTimers() (line 758), which loops get(0) through get(7) without checking list size.

The Trigger

The data recovery process (Phase 5) produced a valid JSON file with "slotTimers": []. This is structurally valid JSON but semantically broken — the plugin expects exactly 8 entries. The plugin has no defensive initialization or size check for this field.

Error Signature

WARN  n.runelite.client.eventbus.EventBus - Uncaught exception in event subscriber
java.lang.IndexOutOfBoundsException: Index 1 out of bounds for length 0
    at java.base/java.util.Objects.checkIndex(Unknown Source)
    at java.base/java.util.ArrayList.get(Unknown Source)
    at com.flippingutilities.controller.NewOfferEventPipelineHandler.screenOfferEvent(NewOfferEventPipelineHandler.java:163)

Why Only Some Items Appeared

GE History Tab imports bypass screenOfferEvent() entirely — they use a separate code path that inserts offers with slot = -1 directly into the history. These continued working, which masked the fact that real-time recording was completely broken.

Affected Versions

  • Flipping Utilities v1.4.1 (confirmed)
  • Likely all versions that use slotTimers without bounds checking

Impact

  • ~16 days of real-time trade data lost (Feb 26 - Mar 14, 2026)
  • All GE slots affected (plugin-wide failure, not per-slot)
  • No user-visible error in the plugin UI

Fix

Populate slotTimers with 8 default SlotActivityTimer entries:

"slotTimers": [
    {"slotIndex": 0, "offerOccurredAtUnknownTime": false},
    {"slotIndex": 1, "offerOccurredAtUnknownTime": false},
    {"slotIndex": 2, "offerOccurredAtUnknownTime": false},
    {"slotIndex": 3, "offerOccurredAtUnknownTime": false},
    {"slotIndex": 4, "offerOccurredAtUnknownTime": false},
    {"slotIndex": 5, "offerOccurredAtUnknownTime": false},
    {"slotIndex": 6, "offerOccurredAtUnknownTime": false},
    {"slotIndex": 7, "offerOccurredAtUnknownTime": false}
]

Fix script: scripts/phase6-slot-timer-fix/fix_slot_timers.ps1

Applied manually on March 14, 2026 with RuneLite closed. Backup created at Knife Lord.json.pre-fix-backup.

Upstream Vulnerability

This is a latent bug in the upstream Flipping Utilities plugin (Flipping-Utilities/rl-plugin). Any scenario that produces an empty or undersized slotTimers list will trigger it:

  • Data file corruption/recovery
  • Manual JSON editing
  • Downgrade from a version that changed the slotTimers schema
  • Race condition during first-time account initialization

The fix should be a bounds check or defensive initialization in screenOfferEvent() and setWidgetsOnSlotTimers().