fix: resolve model aliases in setSessionConfigOption (#401)

[mudrii]

Summary

Fixes #401 by enabling model alias/fuzzy resolution in setSessionConfigOption when updating the model config option.

Root cause

setSessionConfigOption validated model values using an exact string match against config option values (model IDs like claude-opus-4-5):

const validValue = allValues.find((o) => o.value === params.value);

Clients often send human-friendly model preferences (opus, sonnet, Claude Sonnet), which failed this exact check and produced:

• Invalid value for config option model: <value>

The file already had resolveModelPreference(...), which supports exact/display/substring/tokenized matching, but that logic was only used in model initialization paths and not in setSessionConfigOption.

What changed

1) Fuzzy model resolution in setSessionConfigOption

• Kept the existing exact-match validation path.
• When configId === "model" and exact match fails, map config option entries to ModelInfo[] (value + displayName) and call resolveModelPreference(...).
• If resolution succeeds, use the resolved canonical model ID (resolvedValue) for:
  • query.setModel(...)
  • session.configOptions current value update
  • response payload (configOptions)

2) Notification behavior unchanged by design

• Intentionally did not add updateConfigOption(...) in setSessionConfigOption.
• This preserves existing behavior/tests that verify no config_option_update notification is sent for this RPC (response already returns full configOptions).

Tests

Added focused coverage in src/tests/session-config-options.test.ts under describe("setSessionConfigOption"):

• resolves model alias opus -> claude-opus-4-5
• resolves model alias sonnet -> claude-sonnet-4-5
• resolves display name Claude Sonnet -> claude-sonnet-4-5
• still accepts exact model ID
• still throws for invalid model value (gpt-4)

Behavior before / after

Before

• setSessionConfigOption({ configId: "model", value: "opus" }) -> error

After

• same call resolves to canonical ID and succeeds:
  • setModel("claude-opus-4-5")
  • returned configOptions.model.currentValue === "claude-opus-4-5"

Verification

• npm run build ✅
• npm test ✅ (all tests passing)

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[cla-bot]

We require contributors to sign our Contributor License Agreement, and we don't have @mudrii on file. You can sign our CLA at https://zed.dev/cla. Once you've signed, post a comment here that says '@cla-bot check'.

[mudrii]

We require contributors to sign our Contributor License Agreement, and we don't have @mudrii on file. You can sign our CLA at https://zed.dev/cla. Once you've signed, post a comment here that says '@cla-bot check'.

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