Page 5 of 8~104 min topic

Choosing a model

Anticipate failure modes

Name failures by their mechanism in model selection on the invoice-extraction service, not with a generic hallucination label.

~13 min this pageFailure modes

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Response design

For each severe model selection failure on the invoice-extraction service, define stop condition, safe state, owner, and lasting prevention. Rollback only works if prior prompts, indexes, and models remain available. “Send to a human” needs queue capacity and context—not just a button name.

Run one tabletop on the invoice-extraction service for model selection: inject a defect, verify detection, contain, recover, and keep the blameless trace.

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Make it operational

After the tabletop, store the injected model selection defect for the invoice-extraction service as a regression fixture. If the same failure later reaches users silently, your detection story was aspirational. Detection without a fixture tends to rot for model selection.

Also pin one numeric memory from this model selection chapter: If model L hits 96% field-F1 at $0.12/1k docs and model H hits 97% at $0.55/1k, the +1 pt may lose unless errors are extremely costly. That number is not decoration; it is a template for how claims about model selection on the invoice-extraction service should look in design docs. Scoped specifically to model selection / invoice-extraction service / failure-modes.

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Common mix-ups

People confuse model selection with neighboring buzzwords when debugging the invoice-extraction service. Before changing prompts, ask whether the broken stage was evidence gathering, the model selection judgment itself, validation, or the product action. Fixing the wrong stage creates folklore (“we tried model selection and it failed”) that blocks the next team on the invoice-extraction service. Scoped specifically to model selection / invoice-extraction service / failure-modes.

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Rehearsal (choosing-a-model/failure-modes)

Write a five-line artifact for this page: goal, inputs, check, owner, stop rule. Invent one fluent failure that the check would catch. Keep details specific to choosing a model rather than generic AI advice.

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Rehearsal (choosing-a-model/failure-modes)

Write a five-line artifact for this page: goal, inputs, check, owner, stop rule. Invent one fluent failure that the check would catch. Keep details specific to choosing a model rather than generic AI advice.

Read

Rehearsal (choosing-a-model/failure-modes)

Write a five-line artifact for this page: goal, inputs, check, owner, stop rule. Invent one fluent failure that the check would catch. Keep details specific to choosing a model rather than generic AI advice.

Go deeper

Before you start

Why this matters

Invent an incident for the invoice-extraction service involving model selection. What earliest signal should fire before users complain?

Leaderboard shopping

Detect with general chat win hides extraction misses. Respond by task-specific gold set.

Hidden context limits

Detect with long invoices truncate silently. Respond by measure truncation rate.

Vendor feature mismatch

Detect with JSON mode missing in the cheap tier. Respond by prove features on the exact endpoint.

No fallback

Detect with primary outage blocks billing. Respond by document secondary model with parity tests.

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1. What is one idea from this page you would apply, and what evidence would you check?

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