fix(translator/antigravity): support max_completion_tokens in openai chat completions

[warelik]

Problem

OpenAI deprecated max_tokens in favor of max_completion_tokens for reasoning models (o1, o3-mini, newer gpt-4o versions), and modern OpenAI client libraries send max_completion_tokens by default.

When translating OpenAI Chat Completions requests to Antigravity (ConvertOpenAIRequestToAntigravity), only max_tokens was inspected. When a client supplied max_completion_tokens without max_tokens, request.generationConfig.maxOutputTokens was omitted from the upstream Antigravity payload, causing upstream models to ignore client token limits.

Fix

• internal/translator/antigravity/openai/chat-completions/antigravity_openai_request.go:72: Updated ConvertOpenAIRequestToAntigravity to read max_tokens first, and if absent/non-numeric, fall back to max_completion_tokens (matching the mapping pattern used in gemini_openai_request.go).

Tests

• TestConvertOpenAIRequestToAntigravityMapsMaxTokens:
  • only max_tokens: Verifies max_tokens sets maxOutputTokens.
  • only max_completion_tokens: Verifies max_completion_tokens sets maxOutputTokens.
  • max_tokens preferred over max_completion_tokens: Verifies max_tokens precedence when both are provided.
  • neither present: Verifies maxOutputTokens is omitted.
  • non-numeric max_tokens ignored: Verifies string max_tokens is ignored.
  • non-numeric max_completion_tokens ignored: Verifies string max_completion_tokens is ignored.

Reverse bite-check

Reverting internal/translator/antigravity/openai/chat-completions/antigravity_openai_request.go to the pre-fix state reproduces the failure where max_completion_tokens is ignored:

=== RUN   TestConvertOpenAIRequestToAntigravityMapsMaxTokens
=== RUN   TestConvertOpenAIRequestToAntigravityMapsMaxTokens/only_max_tokens
=== RUN   TestConvertOpenAIRequestToAntigravityMapsMaxTokens/only_max_completion_tokens
    antigravity_openai_request_test.go:513: expected maxOutputTokens to be set, but it was missing. Output: {"project":"","request":{"contents":[{"role":"user","parts":[{"text":"hi"}]}],"safetySettings":[{"category":"HARM_CATEGORY_HARASSMENT","threshold":"OFF"},{"category":"HARM_CATEGORY_HATE_SPEECH","threshold":"OFF"},{"category":"HARM_CATEGORY_SEXUALLY_EXPLICIT","threshold":"OFF"},{"category":"HARM_CATEGORY_DANGEROUS_CONTENT","threshold":"OFF"},{"category":"HARM_CATEGORY_CIVIC_INTEGRITY","threshold":"BLOCK_NONE"}]},"model":"gemini-2.5-pro"}
=== RUN   TestConvertOpenAIRequestToAntigravityMapsMaxTokens/max_tokens_preferred_over_max_completion_tokens
=== RUN   TestConvertOpenAIRequestToAntigravityMapsMaxTokens/neither_present
=== RUN   TestConvertOpenAIRequestToAntigravityMapsMaxTokens/non-numeric_max_tokens_ignored
=== RUN   TestConvertOpenAIRequestToAntigravityMapsMaxTokens/non-numeric_max_completion_tokens_ignored
--- FAIL: TestConvertOpenAIRequestToAntigravityMapsMaxTokens (0.00s)
    --- PASS: TestConvertOpenAIRequestToAntigravityMapsMaxTokens/only_max_tokens (0.00s)
    --- FAIL: TestConvertOpenAIRequestToAntigravityMapsMaxTokens/only_max_completion_tokens (0.00s)
    --- PASS: TestConvertOpenAIRequestToAntigravityMapsMaxTokens/max_tokens_preferred_over_max_completion_tokens (0.00s)
    --- PASS: TestConvertOpenAIRequestToAntigravityMapsMaxTokens/neither_present (0.00s)
    --- PASS: TestConvertOpenAIRequestToAntigravityMapsMaxTokens/non-numeric_max_tokens_ignored (0.00s)
    --- PASS: TestConvertOpenAIRequestToAntigravityMapsMaxTokens/non-numeric_max_completion_tokens_ignored (0.00s)
FAIL
FAIL	github.com/router-for-me/CLIProxyAPI/v7/internal/translator/antigravity/openai/chat-completions	0.407s
FAIL

Verification

TMPDIR=/Users/warelik/.cache/gotmp GOCACHE=/Users/warelik/.cache/gocache go build ./...
TMPDIR=/Users/warelik/.cache/gotmp GOCACHE=/Users/warelik/.cache/gocache go vet ./internal/translator/antigravity/openai/chat-completions/...
gofmt -l internal/translator/antigravity/openai/chat-completions/antigravity_openai_request.go internal/translator/antigravity/openai/chat-completions/antigravity_openai_request_test.go
TMPDIR=/Users/warelik/.cache/gotmp GOCACHE=/Users/warelik/.cache/gocache go test -v -run "TestConvertOpenAIRequestToAntigravityMapsMaxTokens" ./internal/translator/antigravity/openai/chat-completions/...

Output:

=== RUN   TestConvertOpenAIRequestToAntigravityMapsMaxTokens
=== RUN   TestConvertOpenAIRequestToAntigravityMapsMaxTokens/only_max_tokens
=== RUN   TestConvertOpenAIRequestToAntigravityMapsMaxTokens/only_max_completion_tokens
=== RUN   TestConvertOpenAIRequestToAntigravityMapsMaxTokens/max_tokens_preferred_over_max_completion_tokens
=== RUN   TestConvertOpenAIRequestToAntigravityMapsMaxTokens/neither_present
=== RUN   TestConvertOpenAIRequestToAntigravityMapsMaxTokens/non-numeric_max_tokens_ignored
=== RUN   TestConvertOpenAIRequestToAntigravityMapsMaxTokens/non-numeric_max_completion_tokens_ignored
--- PASS: TestConvertOpenAIRequestToAntigravityMapsMaxTokens (0.00s)
    --- PASS: TestConvertOpenAIRequestToAntigravityMapsMaxTokens/only_max_tokens (0.00s)
    --- PASS: TestConvertOpenAIRequestToAntigravityMapsMaxTokens/only_max_completion_tokens (0.00s)
    --- PASS: TestConvertOpenAIRequestToAntigravityMapsMaxTokens/max_tokens_preferred_over_max_completion_tokens (0.00s)
    --- PASS: TestConvertOpenAIRequestToAntigravityMapsMaxTokens/neither_present (0.00s)
    --- PASS: TestConvertOpenAIRequestToAntigravityMapsMaxTokens/non-numeric_max_tokens_ignored (0.00s)
    --- PASS: TestConvertOpenAIRequestToAntigravityMapsMaxTokens/non-numeric_max_completion_tokens_ignored (0.00s)
PASS
ok  	github.com/router-for-me/CLIProxyAPI/v7/internal/translator/antigravity/openai/chat-completions	0.384s

Tooling note

The jbcontext semantic-search CLI is installed but non-functional in this environment
(jbcontext search fails with the OS keychain is not accessible). The equivalent
review passes were performed with the repository's own tooling and manual inspection
instead; this is disclosed for transparency about how the change was reviewed.