[craigalbrecht]

Issue for this PR

Closes #60290

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

normalize.migrateProviders decodes each legacy provider with decodeValue(ConfigProviderV1.Info, ...) and returns [] when decoding fails, so a single model that fails validation removes the entire provider and all of its other models.

ConfigProviderV1.Model.limit required both context and output, while the V2 schema makes all three optional. A config that overrides only the output limit — "limit": { "output": 16000 }, a normal V2 shape — therefore failed V1 decoding and silently deleted its provider.

This makes context and output optional in the V1 schema and guards undefined in migrateModel, matching how input was already handled.

Symptom seen in the wild: 3,648 configuration normalization diagnostic warnings over two days, and two providers whose only offending models set limit.output alone — those providers then threw ModelUnavailableError at runtime while their siblings worked.

How did you verify your code works?

A regression test in packages/core/test/config/normalization.test.ts asserts that a provider with one partial-limit model and one full-limit model survives with both models present.

It fails on current dev:

(fail) legacy provider decoding > keeps a provider whose model overrides only limit.output
Received: []          <- the providers array is empty; the whole provider was dropped

and passes with the change:

 42 pass
 0 fail
 354 expect() calls

tsc -b in packages/core is clean. The wider test/config/ suite has two failures (excludes home-level claude…, deduplicates global ecosystem directories…) that fail identically on pristine source because they inspect the machine's home directory — not caused by this change.

Visual

No visual change. This is config normalization: the diff makes two schema fields optional and guards undefined in the migration, so providers decode instead of being discarded.

Screenshots / recordings

N/A — no UI surface.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[opencodejr]

Thanks for tracking this down and writing up the diagnosis so clearly!

I think this duplicates an existing pull request:

• fix(core): preserve partial model limits #53129: makes the same change in packages/core/src/v1/config/provider.ts (limit.context and limit.output become optional) and in migrate.ts (skip int() when they're undefined). It also adds regression tests for partial limits in normalization.test.ts and provider.test.ts. It fixes Cannot change the limits of a model #53005, which reports the same bug as core: a model that overrides only limit.output drops its entire provider #60290.

So I'm closing this one in favour of #53129. If you think it's missing something, such as your specific case of a provider with one partial-limit model and one full-limit model, please review it, test it or comment there. The real-world symptoms you saw (the warning counts and the ModelUnavailableError) would be useful context on that pull request and on #53005.

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