MQ
MODELQUEST
choose the right AI for the quest
← Quests
Quest Fitq_fix_hard_bugpeer min-max inputs

Fix a Difficult Bug

Best when the issue is non-obvious — race conditions, integration failures, flaky tests, or bugs that hide across layers. Favours causal reasoning, debugging skill, reliability, and restraint (smallest correct change).

SharePost on X
How to read this

Fit score ≠ absolute IQ

  • Fit score is a weighted blend of this Quest’s attribute/skill weights (and optional cost/tempo soft prefs). Higher = better match for this job among scored Builds.
  • Attribute inputs are peer-public scores (roughly 40–95 within the current peer set). A low STR here can still be a strong absolute model — it just ranks lower among current scored peers on that axis.
  • Decisive means the leader is ≥4 fit points ahead of #2. Smaller gaps → pick on price, Party stack, or taste.

Peer set today: 6 scored Builds. Adding another re-ranks peers — re-run the engine after new evidence.

Recommendation

Best fit

#1GPT-5.6 Sol · API · Max effortDecisive

Decisive lead on weighted fit. Strongest blend on INT + STR. OpenAI flagship Build for autonomous coding and professional workflows when ecosystem tools and max reasoning justify $5/$30.

Test Writing 96CON · Reliability 95INT · Reasoning 95

Struggle · WIS · Judgment is a relative soft spot (40 peer public)

Fit
88.2
conf A
Open character sheet →Compare in Duels →
Party

Suggested multi-model stack

Most jobs want a Party — not one model forever. Primary handles the Quest; ceiling covers hard escalations; value handles volume and drafts.

Primary
GPT-5.6 Sol · API · Max effort
Fit 88.2 · $5/$30

Decisive Quest Fit lead — default seat for this job.

Ceiling / hard mode
Claude Opus 4.8 · API · High effort (default)
Fit 80.5 · $5/$25

Peer INT 85 — escalate hard reasoning or research here.

Value / volume
DeepSeek V4 Pro · API · Max effort
Fit 55.6 · $0.435/$0.87

Cheapest list stack among remaining candidates ($0.435/$0.87) for volume or drafts.

This Quest

What we weight

Relative importance of each input in the Fit formula.

INT · Reasoning25%
STR · Execution20%
CON · Reliability20%
Debugging15%
WIS · Judgment10%
Existing Codebase Work5%
Test Writing5%
Constraints
  • Prefer minimal diffs; punish speculative rewrites in recommendation copy.
#1 · GPT-5.6 Sol · API · Max effort

Contribution breakdown

Peer-public input × Quest weight. Bars show weight mass; numbers show the score fed into Fit.

INT · Reasoning95 × 25%w
STR · Execution95 × 20%w
CON · Reliability95 × 20%w
Debugging89 × 15%w
WIS · Judgment40 × 10%w
Existing Codebase Work87 × 5%w
Test Writing96 × 5%w
Coverage 100% of Quest weight has evidence
Full ranking

All scored candidates

#1GPT-5.6 Sol · API · Max effortDecisive

Decisive lead on weighted fit. Strongest blend on INT + STR. OpenAI flagship Build for autonomous coding and professional workflows when ecosystem tools and max reasoning justify $5/$30.

Test Writing 96CON · Reliability 95INT · Reasoning 95

Struggle · WIS · Judgment is a relative soft spot (40 peer public)

Fit
88.2
conf A
#2Claude Opus 4.8 · API · High effort (default)

7.7 fit points behind GPT-5.6 Sol · API · Max effort. Still solid where INT / STR matter. The job is hard enough that a wrong answer costs more than Opus tokens.

Test Writing 89INT · Reasoning 85Debugging 84

Struggle · Everyday chat and low-stakes drafts (use Sonnet/Flash)

Fit
80.5
conf A · −7.7
#3Grok 4.5 · API · High effort

15.5 fit points behind GPT-5.6 Sol · API · Max effort. Still solid where INT / STR matter. You want near-frontier coding and agentic work with strong price and speed.

Test Writing 87Debugging 82Existing Codebase Work 81

Struggle · EU-only deployments until regional GA

Fit
72.7
conf A · −15.5
#4Gemini 3.1 Pro · API · High thinking

17.7 fit points behind GPT-5.6 Sol · API · Max effort. Still solid where INT / STR matter. The quest is research, multimodal, or long-context — not pure SWE ceiling at any price.

WIS · Judgment 95INT · Reasoning 93Debugging 80

Struggle · CON · Reliability is a relative soft spot (42 peer public)

Fit
70.5
conf B · −17.7
#5DeepSeek V4 Pro · API · Max effort

32.6 fit points behind GPT-5.6 Sol · API · Max effort. Still solid where INT / STR matter. You want open-frontier capability at roughly an order of magnitude below Sol/Opus list prices.

WIS · Judgment 79Debugging 78Existing Codebase Work 78

Struggle · CON · Reliability is a relative soft spot (40 peer public)

Fit
55.6
conf A · −32.6
#6Claude Sonnet 5 · API · High effort (default)

38.5 fit points behind GPT-5.6 Sol · API · Max effort. Still solid where INT / STR matter. You want one primary Build for coding and writing that stays pleasant under human supervision, holds constraints, and rarely needs the top-tier price.

Test Writing 80Debugging 72Existing Codebase Work 71

Struggle · STR · Execution is a relative soft spot (40 peer public)

Fit
49.7
conf A · −38.5
Primary Build

Capability snapshot

Peer publicbars = rank in scored peer set (≈40–95) · raw = absolute fusion under the bar
STRExecution
94.9raw 87.9A90.9–98.9
DEXTempo
58.3raw 58.0B48.3–68.3
CONReliability
95.2raw 87.5A91.2–99.2
INTReasoning
94.9raw 88.5A90.9–98.9
WISJudgment
39.9raw 55.8A35.9–43.9
CHACollaboration
95.0raw 91.0B85–100

Peer public ranks feed Fit; raw aggregates stay absolute evidence fusion. Full sheet: Codex →

What matters most

  • Forming and testing causal hypotheses
  • Using tools and logs effectively
  • Verifying the fix without collateral damage

Common failure modes

  • Rewriting large regions instead of isolating the fault
  • Confident guesses without reproduction steps
  • Fixes that pass one case and break adjacent behaviour