Chromie/fix deprecation warning for old model format

[chromiebot]

why

what changed

test plan

---

Summary by cubic

Add a deprecation warning for legacy model names (no slash) while keeping them working, and update errors to guide users to the provider/model format. Also improves provider error handling and adds tests.

• New Features
  • Log level-0 deprecation warning when using legacy names (e.g., "gpt-4o"); suggest "provider/model" (e.g., "openai/gpt-5", "anthropic/claude-sonnet-4").
  • Update UnsupportedModelError to list supported models and include provider/model guidance with examples.
  • Throw UnsupportedModelProviderError in LLMProvider’s default switch case for unknown providers.
  • Add Vitest tests covering deprecation logs, error messages, legacy model support, provider/model format, and invalid providers.

^{Written for commit 71ca391. Summary will update on new commits. Review in cubic}

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Latest commit: 71ca391

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[miguelg719]

Suggested change

	message: `Deprecation warning: Model format "${modelName}" is deprecated. Please use the provider/model format (e.g., "openai/gpt-4o" or "anthropic/claude-3-5-sonnet-latest").`,
	message: `Deprecation warning: Model format "${modelName}" is deprecated. Please use the provider/model format (e.g., "openai/gpt-5" or "anthropic/claude-sonnet-4-5").`,

[miguelg719]

Suggested change

	`Please use the provider/model format instead (e.g., "openai/gpt-4o", "anthropic/claude-3-5-sonnet-latest").`;
	`Please use the provider/model format instead (e.g., "openai/gpt-5", "anthropic/claude-sonnet-4-5").`;

[greptile-apps]

Greptile Overview

Greptile Summary

Added deprecation warnings for legacy model format (e.g., gpt-4o) to guide users toward the new provider/model format (e.g., openai/gpt-4o).

Key changes:

• LLMProvider.getClient() now logs a level 0 deprecation warning when legacy model format is used
• UnsupportedModelError includes a deprecation note with examples of the new format
• Comprehensive test coverage validates backward compatibility and warning behavior
• Legacy format continues to work while users are informed of the preferred approach

Confidence Score: 5/5

• This PR is safe to merge with no risk
• Well-implemented deprecation pattern that maintains full backward compatibility while guiding users to the new format. Comprehensive test coverage validates all scenarios including warnings, errors, and continued functionality.
• No files require special attention

Important Files Changed

Filename	Overview
packages/core/lib/v3/llm/LLMProvider.ts	Added deprecation warning for legacy model format (without slash), maintains backward compatibility while guiding users to new provider/model format
packages/core/lib/v3/types/public/sdkErrors.ts	Enhanced UnsupportedModelError with deprecation note explaining the new provider/model format with examples
packages/core/tests/model-deprecation.test.ts	Comprehensive test suite validating deprecation warnings, error messages, and backward compatibility for legacy model names

Sequence Diagram

sequenceDiagram
    participant User
    participant LLMProvider
    participant Logger
    participant ModelMap
    participant ClientFactory
    
    User->>LLMProvider: getClient("gpt-4o")
    LLMProvider->>LLMProvider: Check if modelName includes "/"
    
    alt New format (contains "/")
        LLMProvider->>ClientFactory: Create AISdkClient
        ClientFactory-->>LLMProvider: Return client
    else Legacy format (no "/")
        LLMProvider->>ModelMap: Lookup provider for "gpt-4o"
        ModelMap-->>LLMProvider: Return "openai"
        
        alt Model not found
            LLMProvider->>User: Throw UnsupportedModelError<br/>(with deprecation note)
        else Model found
            LLMProvider->>Logger: Log deprecation warning (level 0)
            Logger-->>User: Display warning message
            LLMProvider->>ClientFactory: Create legacy client (OpenAIClient)
            ClientFactory-->>LLMProvider: Return client
        end
    end
    
    LLMProvider-->>User: Return LLMClient

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[greptile-apps]

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[cubic-dev-ai]

1 issue found across 3 files

Confidence score: 4/5

• Safe to merge overall; the only noted issue is a low-severity test weakness rather than a runtime bug.
• packages/core/tests/model-deprecation.test.ts may silently pass if getClient stops throwing because assertions live only inside a try/catch, reducing confidence in the test’s signal.
• Pay close attention to packages/core/tests/model-deprecation.test.ts - assertions can be skipped if no exception is thrown.

Prompt for AI agents (all issues)

Check if these issues are valid — if so, understand the root cause of each and fix them.


<file name="packages/core/tests/model-deprecation.test.ts">

<violation number="1" location="packages/core/tests/model-deprecation.test.ts:132">
P2: Test does not fail if getClient stops throwing; assertions are only inside try/catch, so the error path can be skipped silently.</violation>
</file>

Architecture diagram

sequenceDiagram
    participant Client as User Code
    participant Provider as LLMProvider
    participant Log as Logger

    Note over Client, Provider: Flow: resolving model names to clients

    Client->>Provider: getClient(modelName, options)

    alt modelName contains "/" (e.g. "openai/gpt-4o")
        Note over Provider: Standard V3 flow (unchanged)
        Provider->>Provider: Instantiate provider from prefix
    else CHANGED: Legacy format (e.g. "gpt-4o")
        Provider->>Provider: Lookup legacy model map

        alt Legacy Mapping Not Found
            Note right of Provider: CHANGED: Error message now<br/>explicitly suggests "provider/model" format
            Provider--XClient: Throw UnsupportedModelError
        else Legacy Mapping Found
            Note right of Log: NEW: Level 0 Deprecation Warning<br/>(Suggests new format)
            Provider->>Log: log("Deprecation warning: ...")
            
            alt Switch Case: Known Provider (OpenAI/Anthropic)
                Provider->>Provider: Instantiate legacy client
            else NEW: Switch Default (Provider in map but not in switch)
                Provider--XClient: Throw UnsupportedModelProviderError
            end
        end
    end

    Provider-->>Client: Return LLMClient Instance

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_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

P2: Test does not fail if getClient stops throwing; assertions are only inside try/catch, so the error path can be skipped silently.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At packages/core/tests/model-deprecation.test.ts, line 132:

<comment>Test does not fail if getClient stops throwing; assertions are only inside try/catch, so the error path can be skipped silently.</comment>

<file context>
@@ -0,0 +1,196 @@
+      const logger = (line: LogLine) => logs.push(line);
+      const provider = new LLMProvider(logger);
+
+      try {
+        provider.getClient("some-unknown-model" as any, mockClientOptions);
+      } catch (error) {
</file context>